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Editor Work2013 Vol. 21, No. 1
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2013, 21(1): 1-5.
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As a New Spring Wish of this Journal of Engineering Geology, I present a global review of the advances in engineering geosciences over the last century in this paper. I look back the origin and evolution of engineering geosciences, discuss their core values and changes of the theoretical bases, and point out the thoughts and prospects for the future. At present, science and technology have been progressed greatly. More and more people have pay attentions to the harmonic relationship between our human beings and the mother Earth. New great breakthroughs in science and technology have been emerging. I hope all the friends and colleagues in China's engineering geology communities think and prepare for the possible impacts of the prospective breakthroughs and the further advancement and future of the geo-engineering professions. For brighter future, we all together make new contributions in the coming year of Snake and sebsquent years.
As a New Spring Wish of this Journal of Engineering Geology, I present a global review of the advances in engineering geosciences over the last century in this paper. I look back the origin and evolution of engineering geosciences, discuss their core values and changes of the theoretical bases, and point out the thoughts and prospects for the future. At present, science and technology have been progressed greatly. More and more people have pay attentions to the harmonic relationship between our human beings and the mother Earth. New great breakthroughs in science and technology have been emerging. I hope all the friends and colleagues in China's engineering geology communities think and prepare for the possible impacts of the prospective breakthroughs and the further advancement and future of the geo-engineering professions. For brighter future, we all together make new contributions in the coming year of Snake and sebsquent years.
2013, 21(1): 6-15.
On January 11,2013,a large landslide occurred in Zhenxiong county, Yunnan Province. The debris traveled about 850m. The debris volume was about 400,000m3. More than 60 houses in Zhaojiagou village were destroyed.46 persons were killed by the debris. This paper presents the field investigation on the cause of the landslide which unusually occurred in dry-season. It uses finite element method to analyze the mechanism of landslide under the conditions of long-term rainfall and coal mining. In geology, the landslide site located in coal-related strata which is common in Wu-meng mountains. The upper strata are limestone and dolomite of high bedding dip angles and middle Triassic epoch. The middle strata are sand shale of relatively high bedding dip angles and lower Triassic epoch. The bottom strata are shale and mudstone with coal seams of gentle bedding dip angles and upper Permian epoch. The strata system has an upper hard and lower soft structure in engineering geology and an upper rich and lower poor groundwater structure in hydrogeology. It is very vulnerable to landslide disasters. The site topography looks like a boot-shaped profile from top to bottom. The upper ground is steep and easy to be unstable. The middle and bottom grounds are wide and gentle. The ground profile offers the condition for long run-out motion and makes potential energy to transfer into kinetic energy. Therefore, the site can easily form high-speed and long travel distance landslide that causes disasters. The landslide zone can be divided into landslide source area, shoveling and stripping and deposition area and debris covered village disaster area. The flying landslide debris with high speed directly slipped and covered over the village houses. In the meantime, the rest ejected debris liquefied and rushed and buried other village houses along the gentle stream valley. They became the most important reason for the huge disaster. The finite element simulation results show the following. The rainfall led the groundwater table rising, which caused a more than 10% reduction of the factor of safety value of the slope. This result may demonstrate that the slope colluvium on steep stream valleys can be triggered to fail by long duration of small rainfall. The coal bed beneath the landslide has relatively thin thickness. The vertical distance of the upper strata between the coal seam and the landslide base is about 200m. The coal mining between 1960 and 1970 did not have noticeable effect to the slope deformation and stability. Based on the social problem induced by this landslide disaster, the authors put forward the following suggestions: to reinforce the public risk management and responding of huge geological disaster, to enhance the early recognition of high speed and long travel distance landslides in coal bed related strata areas, to improve the professional training of complex geological disaster prevention.
On January 11,2013,a large landslide occurred in Zhenxiong county, Yunnan Province. The debris traveled about 850m. The debris volume was about 400,000m3. More than 60 houses in Zhaojiagou village were destroyed.46 persons were killed by the debris. This paper presents the field investigation on the cause of the landslide which unusually occurred in dry-season. It uses finite element method to analyze the mechanism of landslide under the conditions of long-term rainfall and coal mining. In geology, the landslide site located in coal-related strata which is common in Wu-meng mountains. The upper strata are limestone and dolomite of high bedding dip angles and middle Triassic epoch. The middle strata are sand shale of relatively high bedding dip angles and lower Triassic epoch. The bottom strata are shale and mudstone with coal seams of gentle bedding dip angles and upper Permian epoch. The strata system has an upper hard and lower soft structure in engineering geology and an upper rich and lower poor groundwater structure in hydrogeology. It is very vulnerable to landslide disasters. The site topography looks like a boot-shaped profile from top to bottom. The upper ground is steep and easy to be unstable. The middle and bottom grounds are wide and gentle. The ground profile offers the condition for long run-out motion and makes potential energy to transfer into kinetic energy. Therefore, the site can easily form high-speed and long travel distance landslide that causes disasters. The landslide zone can be divided into landslide source area, shoveling and stripping and deposition area and debris covered village disaster area. The flying landslide debris with high speed directly slipped and covered over the village houses. In the meantime, the rest ejected debris liquefied and rushed and buried other village houses along the gentle stream valley. They became the most important reason for the huge disaster. The finite element simulation results show the following. The rainfall led the groundwater table rising, which caused a more than 10% reduction of the factor of safety value of the slope. This result may demonstrate that the slope colluvium on steep stream valleys can be triggered to fail by long duration of small rainfall. The coal bed beneath the landslide has relatively thin thickness. The vertical distance of the upper strata between the coal seam and the landslide base is about 200m. The coal mining between 1960 and 1970 did not have noticeable effect to the slope deformation and stability. Based on the social problem induced by this landslide disaster, the authors put forward the following suggestions: to reinforce the public risk management and responding of huge geological disaster, to enhance the early recognition of high speed and long travel distance landslides in coal bed related strata areas, to improve the professional training of complex geological disaster prevention.
2013, 21(1): 16-24.
The rapid assessment method on seismic landslide hazard based on simplified Newmark displacement model is preliminarily developed, in Wenchuan Ms 8.0 earthquake severely afflicted 11 counties. With the real-time earthquake ground motion parameters, empirical engineering geology lithology formations, topographic slope data, the module of seismic landslide hazard rapid assessment is produced based on ArcGIS spatial data modeller tools. Static safety factor Fs and critical acceleration ac of regional shallow saturated rock and soil mass slope are calculated, according to which seismic landslide susceptibility is assessed. The Arias intensity of Wenchuan earthquake and regional landslide displacement DN distribution are calculated with empirical formula, based on which rapid assessment of seismic landslide hazard in Wenchuan earthquake severely afflicted area is realized. The assessment results can be reference for emergency response decision-making. It is indicated that tens of catastrophic landslides are almost totally located in extreme high-high hazard zone, which within both sides about 20km of Longmenshan central fault belt through comparing the seismic landslide investigation and assessment results. The comparing result indicates the well reliability of assessing model. Meanwhile, the limitation is also analyzed that local assessment result is inaccurate due to poor spatial data accuracy and update. Some improvement suggestion is provided.
The rapid assessment method on seismic landslide hazard based on simplified Newmark displacement model is preliminarily developed, in Wenchuan Ms 8.0 earthquake severely afflicted 11 counties. With the real-time earthquake ground motion parameters, empirical engineering geology lithology formations, topographic slope data, the module of seismic landslide hazard rapid assessment is produced based on ArcGIS spatial data modeller tools. Static safety factor Fs and critical acceleration ac of regional shallow saturated rock and soil mass slope are calculated, according to which seismic landslide susceptibility is assessed. The Arias intensity of Wenchuan earthquake and regional landslide displacement DN distribution are calculated with empirical formula, based on which rapid assessment of seismic landslide hazard in Wenchuan earthquake severely afflicted area is realized. The assessment results can be reference for emergency response decision-making. It is indicated that tens of catastrophic landslides are almost totally located in extreme high-high hazard zone, which within both sides about 20km of Longmenshan central fault belt through comparing the seismic landslide investigation and assessment results. The comparing result indicates the well reliability of assessing model. Meanwhile, the limitation is also analyzed that local assessment result is inaccurate due to poor spatial data accuracy and update. Some improvement suggestion is provided.
2013, 21(1): 25-44.
The latest research results indicate that the 2008 Wenchuan Earthquake(MS 8.0)triggered more than 197000 landslides. Base on Geographic Information Systems(GIS) and remote sensing technologies, three(nearly) complete landslide catalogs are constructed firstly. The three catalogs are corresponds to respective landslide polygons, landside centroid points, and landslide top points respectively. These catalogs indicate that there were 197481 landslides triggered by the Wenchuan earthquake throughout an area of about 110000km2.These landslides are delineated as respective individual solid polygons, landslide central dots, and landslide top dots using visual interpretation of high resolution aerial photographs and satellite images taken pre-and post-earthquake, verified by selected field checking. These landslides cover a total area of about 1160km2.An area covers about 44031km2 is selected as study area. There are 196007 landslides. They have a total area of 1150.6km2 occurred in the study area. This landslide catalog is the most detailed and complete landslide inventory related with the 2008 Wenchuan earthquake. It is also the largest landslide inventory record related to a single earthquake event. Subsequently, spatial distribution statistical analysis of landslides triggered by the 2008 Wenchuan earthquake are carried out in the study area. Base on the inventories of landslide polygons and landslide centroid points, two density maps, named landslide area density map and landslide point density map were constructed, respectively. Both the two landslide density maps show that landslide activities primarily concentrate along the Yingxiu-Beichuan co-seismic surface fault-rupture, and most of the landslides occurred on the hanging wall. The highest landslide density areas appear in the northwest direction areas, on the hanging wall, of a section of the Yingxiu-Beichuan fault(from the Yingxiu Town to the Beichuan County).Those high intensive landslide areas correspond to high deformation areas during the earthquake. So, it can be concluded that the earthquake triggered landslides is very strongly affected by co-seismic deformation. Furthermore, correlations of landslide occurrence with seismic parameters, geologic and topographic conditions are analyzed using the three landslide catalogs. Statistical analysis of these landslides spatial distribution using (a) landslide area percentage(LAP),defined as the percentage of the area affected by the landslides,(b) landslide centroid number density(LCND),defined as the number of landslide centroid per square kilometer, and (c) landslide top number density(LTND),defined as the number of landslide top point per square kilometer, is carried out to determine how the occurrence of landslides correlates with elevation, slope angle, slope aspect, slope position, slope curvature, lithology, distance from epicenter, seismic intensity, distance from the Yingxiu-Beichuan surface fault-rupture, peak ground acceleration(PGA).It is observed that the LAP,LCND, and LTND values have positive correlations with slope angle, PGA, and seismic intensity, and have negative correlations with distance from epicenter, and distance from the Yingxiu-Beichuan surface fault-rupture. More slope curvature close to zero, more difficult to landslide occurrence. The highest values of one LAP and two LND appear at range from 1200m to 3000m in elevation. The landslides have preferred orientations, dominated by the eastern, southeastern, and southern directions. The sandstone, siltstone(Z) and granitic rocks have more concentrated landslides. No apparent correlations were found between LAP,two LND values and slope position. Statistical results also show that differences between LCND and LTND is very small for earthquake and geologic parameters, rather more difference relate with topographic parameters. Some qualitative comparisons between the results in this paper and others published papers are carried out finally. There would be obvious differences of statistical results related to correlations of landsides and elevation, lithology, distance from the epicenter, distance from the Yingxiu-Beichuan fault from the present results and in other publications. In addition to those parameters, the statistical result from other factors including slope angle and slope aspect show similar tendency. So, it can be concluded that a complete, detailed and accurate landslide catalog is an essential part for seismic landslide hazard analyses and spatial distribution statistical analyses. Otherwise, parts of results obtained from analyzing uncompleted landslide distribution data would be controversial. It is rather necessary and important to construct complete landslide catalogs for seismic landslide spatial distribution statistical quantitative analyses, hazard assessment, and landscape evolution controlled by earthquake triggered landslides in earthquake struck area, et al.
The latest research results indicate that the 2008 Wenchuan Earthquake(MS 8.0)triggered more than 197000 landslides. Base on Geographic Information Systems(GIS) and remote sensing technologies, three(nearly) complete landslide catalogs are constructed firstly. The three catalogs are corresponds to respective landslide polygons, landside centroid points, and landslide top points respectively. These catalogs indicate that there were 197481 landslides triggered by the Wenchuan earthquake throughout an area of about 110000km2.These landslides are delineated as respective individual solid polygons, landslide central dots, and landslide top dots using visual interpretation of high resolution aerial photographs and satellite images taken pre-and post-earthquake, verified by selected field checking. These landslides cover a total area of about 1160km2.An area covers about 44031km2 is selected as study area. There are 196007 landslides. They have a total area of 1150.6km2 occurred in the study area. This landslide catalog is the most detailed and complete landslide inventory related with the 2008 Wenchuan earthquake. It is also the largest landslide inventory record related to a single earthquake event. Subsequently, spatial distribution statistical analysis of landslides triggered by the 2008 Wenchuan earthquake are carried out in the study area. Base on the inventories of landslide polygons and landslide centroid points, two density maps, named landslide area density map and landslide point density map were constructed, respectively. Both the two landslide density maps show that landslide activities primarily concentrate along the Yingxiu-Beichuan co-seismic surface fault-rupture, and most of the landslides occurred on the hanging wall. The highest landslide density areas appear in the northwest direction areas, on the hanging wall, of a section of the Yingxiu-Beichuan fault(from the Yingxiu Town to the Beichuan County).Those high intensive landslide areas correspond to high deformation areas during the earthquake. So, it can be concluded that the earthquake triggered landslides is very strongly affected by co-seismic deformation. Furthermore, correlations of landslide occurrence with seismic parameters, geologic and topographic conditions are analyzed using the three landslide catalogs. Statistical analysis of these landslides spatial distribution using (a) landslide area percentage(LAP),defined as the percentage of the area affected by the landslides,(b) landslide centroid number density(LCND),defined as the number of landslide centroid per square kilometer, and (c) landslide top number density(LTND),defined as the number of landslide top point per square kilometer, is carried out to determine how the occurrence of landslides correlates with elevation, slope angle, slope aspect, slope position, slope curvature, lithology, distance from epicenter, seismic intensity, distance from the Yingxiu-Beichuan surface fault-rupture, peak ground acceleration(PGA).It is observed that the LAP,LCND, and LTND values have positive correlations with slope angle, PGA, and seismic intensity, and have negative correlations with distance from epicenter, and distance from the Yingxiu-Beichuan surface fault-rupture. More slope curvature close to zero, more difficult to landslide occurrence. The highest values of one LAP and two LND appear at range from 1200m to 3000m in elevation. The landslides have preferred orientations, dominated by the eastern, southeastern, and southern directions. The sandstone, siltstone(Z) and granitic rocks have more concentrated landslides. No apparent correlations were found between LAP,two LND values and slope position. Statistical results also show that differences between LCND and LTND is very small for earthquake and geologic parameters, rather more difference relate with topographic parameters. Some qualitative comparisons between the results in this paper and others published papers are carried out finally. There would be obvious differences of statistical results related to correlations of landsides and elevation, lithology, distance from the epicenter, distance from the Yingxiu-Beichuan fault from the present results and in other publications. In addition to those parameters, the statistical result from other factors including slope angle and slope aspect show similar tendency. So, it can be concluded that a complete, detailed and accurate landslide catalog is an essential part for seismic landslide hazard analyses and spatial distribution statistical analyses. Otherwise, parts of results obtained from analyzing uncompleted landslide distribution data would be controversial. It is rather necessary and important to construct complete landslide catalogs for seismic landslide spatial distribution statistical quantitative analyses, hazard assessment, and landscape evolution controlled by earthquake triggered landslides in earthquake struck area, et al.
2013, 21(1): 45-52.
After construction of the Three-Gorges Dam, many geo-hazards happened on its Reservoir, The landslides are an outstanding issue. In order to take precautions against natural calamities effectively, adoption of the right technique methods to discuss the stability of landslides is essentially. This paper uses the setting of No.1 landslide at Tangjiaocun village as an example. A full prototype model is constructed in laboratory on the basis of the geology, groups of water and soil testing. Thus, in line with the similarity theory and the optimized similar materials for the landslide, the geological environment simulation test device is used to form a two dimensional geological mechanics model in laboratory. The polyethylene films and geomembrane are used to simulate the landslide soil. Rain and surface water can make the groundwater level change of landslide, to cause the shear strength reduction of landslide soil. So, they can change its stability. Two realistic simulation operations are designed. The model test uses inductance frequency modulation response device, ng notes machine without papers, and monitors the change of displacement and pore-water pressure and soil pressure of this landslide model continuously. The test results show that after rainfall(intensity is 220mmd-1,lasting 3d),while reservoir water level drops to 169m, the instability of landslide is at the leading edge. The deformation stages of the landslide curve of displacement with time can be divided to account the toe part of this landslide transferring from the static deformation stage into the accelerating creep stage directly.
After construction of the Three-Gorges Dam, many geo-hazards happened on its Reservoir, The landslides are an outstanding issue. In order to take precautions against natural calamities effectively, adoption of the right technique methods to discuss the stability of landslides is essentially. This paper uses the setting of No.1 landslide at Tangjiaocun village as an example. A full prototype model is constructed in laboratory on the basis of the geology, groups of water and soil testing. Thus, in line with the similarity theory and the optimized similar materials for the landslide, the geological environment simulation test device is used to form a two dimensional geological mechanics model in laboratory. The polyethylene films and geomembrane are used to simulate the landslide soil. Rain and surface water can make the groundwater level change of landslide, to cause the shear strength reduction of landslide soil. So, they can change its stability. Two realistic simulation operations are designed. The model test uses inductance frequency modulation response device, ng notes machine without papers, and monitors the change of displacement and pore-water pressure and soil pressure of this landslide model continuously. The test results show that after rainfall(intensity is 220mmd-1,lasting 3d),while reservoir water level drops to 169m, the instability of landslide is at the leading edge. The deformation stages of the landslide curve of displacement with time can be divided to account the toe part of this landslide transferring from the static deformation stage into the accelerating creep stage directly.
2013, 21(1): 53-60.
This paper presents a new method of searching for sliding surface and uses it for stability analysis of slopes reinforced with pre-tensioned cables. The reinforcement effect of cables is simplified to an external force on the bottom surface of the soil section(column) when the slice methods are used. The formula for calculating the factor of safety(FOS) is achieved in two-dimensional(2D)or three-dimensional(3D)slopes reinforced with pre-tensioned cables. Some examples are compared and analyzed. The feasibility of the proposed method is verified. Then in a certain extent, the effect on the slope stability with change of cable angle(),length of three-dimensional sliding body(L),anchorage force of cable(F) and horizontal space of reinforcement cable(S) is researched. The numerical results show the follows.(1)Cables can effectively improve the stability of slope, and can increase the range of original slope's sliding surface.(2)As the three-dimension sliding body length(L)increases, the stability of 3D slopes(including non-reinforcement slope and slopes reinforced with cables) tends to the stability of 2D slopes.(3)the greater anchorage force of per meter horizontal reinforcement spacing is,the more anchor cable's reinforcement effect on the slope is.
This paper presents a new method of searching for sliding surface and uses it for stability analysis of slopes reinforced with pre-tensioned cables. The reinforcement effect of cables is simplified to an external force on the bottom surface of the soil section(column) when the slice methods are used. The formula for calculating the factor of safety(FOS) is achieved in two-dimensional(2D)or three-dimensional(3D)slopes reinforced with pre-tensioned cables. Some examples are compared and analyzed. The feasibility of the proposed method is verified. Then in a certain extent, the effect on the slope stability with change of cable angle(),length of three-dimensional sliding body(L),anchorage force of cable(F) and horizontal space of reinforcement cable(S) is researched. The numerical results show the follows.(1)Cables can effectively improve the stability of slope, and can increase the range of original slope's sliding surface.(2)As the three-dimension sliding body length(L)increases, the stability of 3D slopes(including non-reinforcement slope and slopes reinforced with cables) tends to the stability of 2D slopes.(3)the greater anchorage force of per meter horizontal reinforcement spacing is,the more anchor cable's reinforcement effect on the slope is.
2013, 21(1): 61-68.
Mining-out area in slope with gently inclined coal beds always can induce some engineering geological problems including subsidence and cracking of the surface, partial collapse, landslide. They are due to the difference of the goaf size and the slope structure characteristics. They can cause large-scale geological disasters. The Madaling landslide was generated in the slope with gently inclined strata dipping inward with soft rock sandwich and coal mining-out area. The landslide was caused by the mining-out area and the storm. Its volume is up to 190104m3.According to the engineering geological survey and analysis, the weak geologic structure and the damage of the goaf under the slope mainly caused the landslide. The concentrated regional rainfall accelerated the occurrence of the landslide. The formation mechanism of the Madaling landslide is the type of collapse-rip-shear slip.The mechanism and process of the landslide can be divided into three stages as follows: (1)tension cracking of trailing edge of the slope,(2)sliding surface developing and interconnect, and (3)integral failure of the landslide. The sliding mass flowed downstream after disintegration, and formed 1.5km long debris flow accumulation area. Large area farmland was submerged by the debris.
Mining-out area in slope with gently inclined coal beds always can induce some engineering geological problems including subsidence and cracking of the surface, partial collapse, landslide. They are due to the difference of the goaf size and the slope structure characteristics. They can cause large-scale geological disasters. The Madaling landslide was generated in the slope with gently inclined strata dipping inward with soft rock sandwich and coal mining-out area. The landslide was caused by the mining-out area and the storm. Its volume is up to 190104m3.According to the engineering geological survey and analysis, the weak geologic structure and the damage of the goaf under the slope mainly caused the landslide. The concentrated regional rainfall accelerated the occurrence of the landslide. The formation mechanism of the Madaling landslide is the type of collapse-rip-shear slip.The mechanism and process of the landslide can be divided into three stages as follows: (1)tension cracking of trailing edge of the slope,(2)sliding surface developing and interconnect, and (3)integral failure of the landslide. The sliding mass flowed downstream after disintegration, and formed 1.5km long debris flow accumulation area. Large area farmland was submerged by the debris.
2013, 21(1): 69-75.
Because the lock segment can suddenly snip during the process of high speed landslide in the set-out range, the shearing stress is also suddenly released, which can make the pore water pressure near the sliding zone sharply increase. Therefore it greatly reduces the effective stress and makes the landslide has a very high initial velocity. Taking the Ermanshan landslide as example, this paper employs the field survey, laboratory test and theoretical research methods to study such mechanism. The pore water pressure can be affected by the degree of crushing of slip soil particles, which is analyzed. The condition of producing high pore water pressure when landslide starting is given. On the foundation of theoretical research, it shows that the landslide at Ermanshan site has the condition of producing the high pore water pressure through the exploration. By applying the theory of soil mechanics and the results of mechanics of materials, it can conclude the formula of the pore water pressure in the starting-up of the high speed landslide, and the pore water pressure of Ermanshan landslide are computed by this formula. Furthermore it can deeply investigate the pore water pressure effect in the starting-up of the landslide.
Because the lock segment can suddenly snip during the process of high speed landslide in the set-out range, the shearing stress is also suddenly released, which can make the pore water pressure near the sliding zone sharply increase. Therefore it greatly reduces the effective stress and makes the landslide has a very high initial velocity. Taking the Ermanshan landslide as example, this paper employs the field survey, laboratory test and theoretical research methods to study such mechanism. The pore water pressure can be affected by the degree of crushing of slip soil particles, which is analyzed. The condition of producing high pore water pressure when landslide starting is given. On the foundation of theoretical research, it shows that the landslide at Ermanshan site has the condition of producing the high pore water pressure through the exploration. By applying the theory of soil mechanics and the results of mechanics of materials, it can conclude the formula of the pore water pressure in the starting-up of the high speed landslide, and the pore water pressure of Ermanshan landslide are computed by this formula. Furthermore it can deeply investigate the pore water pressure effect in the starting-up of the landslide.
2013, 21(1): 76-84.
As one of the most promising tools for landslide hazard prevention and mitigation, risk assessment has been a hot research topic in recent years. A relatively complete international landslide risk management system has been proposed. However, the domestic research in this field is rather weak and the key support technology system for landslide risk assessment has not been established. This paper investigates the key theory and method for landslide risk assessment, describes the theoretical framework for landslide risk analysis and management and reviews the recent advances in landslide susceptibility, hazard and risk assessment. Then, different approaches for assessing landslide susceptibility, runout, frequency, vulnerability and risk are examined and compared. At the end, this paper illustrates the key areas and cutting-edge scientific issues for landslide risk assessment and three prospects in this area are proposed.
As one of the most promising tools for landslide hazard prevention and mitigation, risk assessment has been a hot research topic in recent years. A relatively complete international landslide risk management system has been proposed. However, the domestic research in this field is rather weak and the key support technology system for landslide risk assessment has not been established. This paper investigates the key theory and method for landslide risk assessment, describes the theoretical framework for landslide risk analysis and management and reviews the recent advances in landslide susceptibility, hazard and risk assessment. Then, different approaches for assessing landslide susceptibility, runout, frequency, vulnerability and risk are examined and compared. At the end, this paper illustrates the key areas and cutting-edge scientific issues for landslide risk assessment and three prospects in this area are proposed.
2013, 21(1): 85-91.
It has been well known that tunnel excavation of subway in urban area can cause ground settlement. Excessive settlement would threaten safety of the tunnel itself and its surrounding buildings. Therefore, it will be of important practical significance to effectively predict and reasonably control this kind of subsidence. According to the excavation in Hu-Ming Section of Wuhan subway, the MIDAS/GTS software is used to build the model of the tunnel excavation. Surface subsidence caused by tunnel excavation is computed, and compared with the measured result. According to the situation of the corresponding ground and building during excavation process, the optimization of the preparative regimens on the surrounding rock excavation is carried out for building the optimization model of the tunnel excavation. The simulation results show the optimized surface subsidence is still in the safe range. The results would offer reference for similar projects in controlling the surface subsidence.
It has been well known that tunnel excavation of subway in urban area can cause ground settlement. Excessive settlement would threaten safety of the tunnel itself and its surrounding buildings. Therefore, it will be of important practical significance to effectively predict and reasonably control this kind of subsidence. According to the excavation in Hu-Ming Section of Wuhan subway, the MIDAS/GTS software is used to build the model of the tunnel excavation. Surface subsidence caused by tunnel excavation is computed, and compared with the measured result. According to the situation of the corresponding ground and building during excavation process, the optimization of the preparative regimens on the surrounding rock excavation is carried out for building the optimization model of the tunnel excavation. The simulation results show the optimized surface subsidence is still in the safe range. The results would offer reference for similar projects in controlling the surface subsidence.
2013, 21(1): 92-96.
The Weihe Basin can be the most developed area of ground fissures and the associated geo-hazard in China and even in the world. Taking the Weihe Basin as the prototype, a numerical analysis with finite element method is made to study the stress and strain response characteristics of superficial ground and multistage fracture system subjected to the action of basement stretching. The germination relationship between deep structure activities and ground fissures development is revealed. Results show that the basement stretching can cause the tensile deformation of superficial ground. When this kind of action is coupled with normal dip-slipping tension of faults, it can inevitably form or aggravate the tension-shear fracturing, and establish the tectonic foundation for the development of ground fissures.
The Weihe Basin can be the most developed area of ground fissures and the associated geo-hazard in China and even in the world. Taking the Weihe Basin as the prototype, a numerical analysis with finite element method is made to study the stress and strain response characteristics of superficial ground and multistage fracture system subjected to the action of basement stretching. The germination relationship between deep structure activities and ground fissures development is revealed. Results show that the basement stretching can cause the tensile deformation of superficial ground. When this kind of action is coupled with normal dip-slipping tension of faults, it can inevitably form or aggravate the tension-shear fracturing, and establish the tectonic foundation for the development of ground fissures.
2013, 21(1): 97-102.
The abilities of different rocks to resist weathering in the same weathering condition are different. How to assess the ability of rock to resist weathering is one of the research topic of great concern in recent years, which has important scientific value for analyzing weathering mechanism of rocks and long-term protection of rock culture relics. The Xiaoxi gate wall of Quzhou ancient city wall was built in late of Ming dynasty(1368～1644A.D.).There are a variety of lithologies in rock blocks of Xiaoxi gate wall. The differences in their depths of surface recession are also large. The three-dimensional(3D)laser scanner is used to measure the depths of surface recession of rock blocks with different lithologies in a particular study area on Xiaoxi gate wall. Based on the measure data, the long-term abilities of different lithologic rocks to resist weathering were assessed and the corresponding sort is attained. It is also found that compared with the rock blocks studied, the ability of shell-limes motar adhered between blocks are stronger.
The abilities of different rocks to resist weathering in the same weathering condition are different. How to assess the ability of rock to resist weathering is one of the research topic of great concern in recent years, which has important scientific value for analyzing weathering mechanism of rocks and long-term protection of rock culture relics. The Xiaoxi gate wall of Quzhou ancient city wall was built in late of Ming dynasty(1368～1644A.D.).There are a variety of lithologies in rock blocks of Xiaoxi gate wall. The differences in their depths of surface recession are also large. The three-dimensional(3D)laser scanner is used to measure the depths of surface recession of rock blocks with different lithologies in a particular study area on Xiaoxi gate wall. Based on the measure data, the long-term abilities of different lithologic rocks to resist weathering were assessed and the corresponding sort is attained. It is also found that compared with the rock blocks studied, the ability of shell-limes motar adhered between blocks are stronger.
2013, 21(1): 103-108.
the rock failure due to freeze-thaw weathering is a main engineering problem which often occurs in the rock engineering in cold regions. The rock-degradation and deterioration mechanism and mechanical characteristics for three kinds of rocks have been studied through the cycle freezing-thawing test and the scanning electron microscope method. The mechanism of rock failure due to freezing and thawing is studied. The process of freezing and thawing failure of two basic deterioration modes of different nature rocks is studied by experiments. The two modes are the crack propagation degradation mode and the particle precipitation degradation mode. In order to providing reliable experimental foundation for studying the damage and fracture due to freezing and thawing and the construction and the safety operation of similar projects in cold region, the uniaxial compression tests of three types of rocks suffered from the different cycles of freezing-thawing action are conducted. The fitting relations of the uniaxial compressive strength with the cycles of freezing and thawing are formulated. Preliminary quantitative influence of the cycle of freezing and thawing to the rock strength attenuation has certain reference value.
the rock failure due to freeze-thaw weathering is a main engineering problem which often occurs in the rock engineering in cold regions. The rock-degradation and deterioration mechanism and mechanical characteristics for three kinds of rocks have been studied through the cycle freezing-thawing test and the scanning electron microscope method. The mechanism of rock failure due to freezing and thawing is studied. The process of freezing and thawing failure of two basic deterioration modes of different nature rocks is studied by experiments. The two modes are the crack propagation degradation mode and the particle precipitation degradation mode. In order to providing reliable experimental foundation for studying the damage and fracture due to freezing and thawing and the construction and the safety operation of similar projects in cold region, the uniaxial compression tests of three types of rocks suffered from the different cycles of freezing-thawing action are conducted. The fitting relations of the uniaxial compressive strength with the cycles of freezing and thawing are formulated. Preliminary quantitative influence of the cycle of freezing and thawing to the rock strength attenuation has certain reference value.
2013, 21(1): 109-114.
In recent years, coarse particle saline soil as a kind of special soils is often encountered in engineering construction in northwest China. In order to grasp the special engineering properties of the soil mass, this study selects 28 test points and 576 pieces samples of 4 test sites in northeastern Xinjiang and Hexi regions of Gansu Province to collapsible testing research. The test results show that the foundation soil can cause salt resolving slump when the easy resolving salt content exceeds 0.5％ ～1％ and the permeability coefficient no less than 10-7. At the same time, the test results show that soil's periodic expansion and contraction phenomenon are more dangerous than single salt expansion and salt resolving slump.
In recent years, coarse particle saline soil as a kind of special soils is often encountered in engineering construction in northwest China. In order to grasp the special engineering properties of the soil mass, this study selects 28 test points and 576 pieces samples of 4 test sites in northeastern Xinjiang and Hexi regions of Gansu Province to collapsible testing research. The test results show that the foundation soil can cause salt resolving slump when the easy resolving salt content exceeds 0.5％ ～1％ and the permeability coefficient no less than 10-7. At the same time, the test results show that soil's periodic expansion and contraction phenomenon are more dangerous than single salt expansion and salt resolving slump.
GIS BASED GEOSTATISTICAL ANALYSIS of FRACTURE DENSITY of GRANITE ROCK in BEISHan AREA GANSU PROVINCE
2013, 21(1): 115-122.
Geometrical parameters of fractures such as joints in natural rocks are important parameters in fluid dynamics of fracture systems, and are also mainly considered factors for the stability analysis of large-scale projects during construction. Therefore, the importance of these parameters has been fully recognized by engineering scientists. The Jijicao block of the Beishan area in Gansu province is chosen as the studied area in this paper. It is a candidate area for high level waste repository in China. The paper chooses the rock mass fracture system of the granite in Jijicao block as the study object. The trace lengths of fracture system are measured by GPS-RTK technique in detail. The occurrence of the bedrock outcrop fractures is surveyed with compass. Then the ArcGIS software is used in the data statistics and calculation and also applied to studying fracture density in the granite area in the Jijicao block. Finally, geostatistical analysis is used to study the spatial autocorrelation and variability of fracture density. By this way the spatial distribution characteristics of fracture can be recognized.The research results indicate that the fracture density has a strong spatial autocorrelation. Variogram analysis demonstrates that P21 values become antocorrelated at a step of about 20～30m. The difference between the ranges of NS and EW demonstrates that there is heterogeneity in the spatial distribution of fractures. At last the prediction map of P21 value is obtained with the method of ordinary kringing interpolation method.
Geometrical parameters of fractures such as joints in natural rocks are important parameters in fluid dynamics of fracture systems, and are also mainly considered factors for the stability analysis of large-scale projects during construction. Therefore, the importance of these parameters has been fully recognized by engineering scientists. The Jijicao block of the Beishan area in Gansu province is chosen as the studied area in this paper. It is a candidate area for high level waste repository in China. The paper chooses the rock mass fracture system of the granite in Jijicao block as the study object. The trace lengths of fracture system are measured by GPS-RTK technique in detail. The occurrence of the bedrock outcrop fractures is surveyed with compass. Then the ArcGIS software is used in the data statistics and calculation and also applied to studying fracture density in the granite area in the Jijicao block. Finally, geostatistical analysis is used to study the spatial autocorrelation and variability of fracture density. By this way the spatial distribution characteristics of fracture can be recognized.The research results indicate that the fracture density has a strong spatial autocorrelation. Variogram analysis demonstrates that P21 values become antocorrelated at a step of about 20～30m. The difference between the ranges of NS and EW demonstrates that there is heterogeneity in the spatial distribution of fractures. At last the prediction map of P21 value is obtained with the method of ordinary kringing interpolation method.
2013, 21(1): 123-128.
There were many times of glacial actions during the pleistocene global ice ages in the Qinghai-Tibet Plateau that is well-known as the roof of the world, leaved a lot of glacial traces. The moraine soil belongs to the special engineering soils, which has complicated composition, mixed structure and changeable physical and mechanical properties. The moraine soil is usually confused with diluvium and eluvium. The site of constructing Yading airport is located at Daocheng Haizi Mountain. Its foundation soil is a typical Qinghai-Tibet Plateau moraine soil, and stacked up after the Daocheng ice cap melt. In order to master the moraine's special physical and mechanical properties, and reveal the relationship between moraine's properties and the glacier evolution, the composition analysis, physical and mechanical properties testing, and ESR dating were carried out during the Yading airport foundation survey. Research shows that the moraine soil of Yading airport, stacked up during 375ka BP and compacted by the glacier, has the characteristics of higher density, lower void ratio, higher foundation deformation modulus and bearing capacity. Moraine soil belongs to the over-consolidated soils(average preconsolidation pressure is about 290kPa) and can be used as a good natural foundation of major engineering in the Qinghai-Tibet Plateau.
There were many times of glacial actions during the pleistocene global ice ages in the Qinghai-Tibet Plateau that is well-known as the roof of the world, leaved a lot of glacial traces. The moraine soil belongs to the special engineering soils, which has complicated composition, mixed structure and changeable physical and mechanical properties. The moraine soil is usually confused with diluvium and eluvium. The site of constructing Yading airport is located at Daocheng Haizi Mountain. Its foundation soil is a typical Qinghai-Tibet Plateau moraine soil, and stacked up after the Daocheng ice cap melt. In order to master the moraine's special physical and mechanical properties, and reveal the relationship between moraine's properties and the glacier evolution, the composition analysis, physical and mechanical properties testing, and ESR dating were carried out during the Yading airport foundation survey. Research shows that the moraine soil of Yading airport, stacked up during 375ka BP and compacted by the glacier, has the characteristics of higher density, lower void ratio, higher foundation deformation modulus and bearing capacity. Moraine soil belongs to the over-consolidated soils(average preconsolidation pressure is about 290kPa) and can be used as a good natural foundation of major engineering in the Qinghai-Tibet Plateau.
2013, 21(1): 129-137.
Landslides forming dynamic mechanism and their response to the global climatic change are becoming a hot and focus issue in geological disasters research. This paper is based on paleo-climate evolution, the evolution of the Yellow River and the chronology of some landslides. It studies typical landslides from Sigou gorge to Lagan gorge in the upper reaches of the Yellow River, where is one geo-hazard high-prone zoning area in China. The spatial and temporal distribution characteristics of the massive landslides and the giant landslides are summarized. The relationship between landslide development periods and the response of landslides to the global climatic change are also analyzed. On the basis of above study, the authors discuss the dynamic mechanism of landslide development and the climate change. They believe that the ancient and old landslides mainly occurred in the warmly and humidly periods and the rapid climate change transition stages. The results of this research are as follows.(1)the landslides of the studied areas distributed widely and led severe geological disasters, particularly in the Qunke-Jianzha Basin. The dynamic mechanism of landslides is very complicated.(2)With dating samples of slip zone of landslides and studying the relation between a landslide and its overlying or under-covering loess formation, the chronology sequence of landslides is established. Five stages of landslide development are divided, i.e.53～49ka B.P.、33～24ka B.P.、10～8ka B.P.、5～3.5ka B.P. and present.(3)the landslides developmental stages are closely corresponds to warm and wet stages over the last 100ka, i.e. ,the two weak paleosol-developed stages of Malan loess of the last glacial period in the Chinese loess Plateau L1-4 and L1-2.They both are belong to the marine oxygen isotope stage 3,the last deglacial period, the Holocene Optimum and the present global warming period.(4)Landslide-triggered drivers may be closely linked to the global climate change. Landslides mainly developed during the warm and wet climatic periods and were related to the rapid climate transitions.
Landslides forming dynamic mechanism and their response to the global climatic change are becoming a hot and focus issue in geological disasters research. This paper is based on paleo-climate evolution, the evolution of the Yellow River and the chronology of some landslides. It studies typical landslides from Sigou gorge to Lagan gorge in the upper reaches of the Yellow River, where is one geo-hazard high-prone zoning area in China. The spatial and temporal distribution characteristics of the massive landslides and the giant landslides are summarized. The relationship between landslide development periods and the response of landslides to the global climatic change are also analyzed. On the basis of above study, the authors discuss the dynamic mechanism of landslide development and the climate change. They believe that the ancient and old landslides mainly occurred in the warmly and humidly periods and the rapid climate change transition stages. The results of this research are as follows.(1)the landslides of the studied areas distributed widely and led severe geological disasters, particularly in the Qunke-Jianzha Basin. The dynamic mechanism of landslides is very complicated.(2)With dating samples of slip zone of landslides and studying the relation between a landslide and its overlying or under-covering loess formation, the chronology sequence of landslides is established. Five stages of landslide development are divided, i.e.53～49ka B.P.、33～24ka B.P.、10～8ka B.P.、5～3.5ka B.P. and present.(3)the landslides developmental stages are closely corresponds to warm and wet stages over the last 100ka, i.e. ,the two weak paleosol-developed stages of Malan loess of the last glacial period in the Chinese loess Plateau L1-4 and L1-2.They both are belong to the marine oxygen isotope stage 3,the last deglacial period, the Holocene Optimum and the present global warming period.(4)Landslide-triggered drivers may be closely linked to the global climate change. Landslides mainly developed during the warm and wet climatic periods and were related to the rapid climate transitions.
2013, 21(1): 138-142.
Using MTS testing machine, the triaxial compression test with four different confining pressures and the uniaxial compression test are carried out on the red mudstone of Badong formation. The complete stress-strain curves of five different confining pressures are obtained. According to the results, the complete stress-strain curve is divided into four main phases. The relationships of the yield strength, the peak strength, and the residual strength with confining pressure are analyzed, respectively. The results show that they get a linear increase relationship with the confining pressure. Also, the bilinear elastic-linear strain softening-residual ideal plastic model is found for the mudstone. The constitutive model of each part is discussed. The related parameters are calculated.
Using MTS testing machine, the triaxial compression test with four different confining pressures and the uniaxial compression test are carried out on the red mudstone of Badong formation. The complete stress-strain curves of five different confining pressures are obtained. According to the results, the complete stress-strain curve is divided into four main phases. The relationships of the yield strength, the peak strength, and the residual strength with confining pressure are analyzed, respectively. The results show that they get a linear increase relationship with the confining pressure. Also, the bilinear elastic-linear strain softening-residual ideal plastic model is found for the mudstone. The constitutive model of each part is discussed. The related parameters are calculated.
2013, 21(1): 143-148.
The rock elastic resistance coefficient K is an important parameter and reflects the resistance of the rock around the tunnel in hydraulic tunnel engineering. It is found that the elastic resistance coefficient calculated by tunnel excavation supporting is entirely consistent with the coefficient calculated by hydrostatic test. The finding is based on the comparative analysis of mechanical effect relations under elastic state between tunnel excavation supporting and hydrostatic test. Back analysis method of elastic resistant coefficient from the measured displacements of the tunnels is proposed. According to the construction of shallow buried hydraulic tunnel in loose ground, a comprehensive monitoring on the displacements of the tunnel is performed during construction. Based on the measured data and the proposed inversion method of elastic resistant coefficient, the elastic resistant coefficient is obtained. The method, analysis and conclusion of research can be valuable experience and reference for design, construction, supervision and further theoretical research on tunnel engineering under similar conditions.
The rock elastic resistance coefficient K is an important parameter and reflects the resistance of the rock around the tunnel in hydraulic tunnel engineering. It is found that the elastic resistance coefficient calculated by tunnel excavation supporting is entirely consistent with the coefficient calculated by hydrostatic test. The finding is based on the comparative analysis of mechanical effect relations under elastic state between tunnel excavation supporting and hydrostatic test. Back analysis method of elastic resistant coefficient from the measured displacements of the tunnels is proposed. According to the construction of shallow buried hydraulic tunnel in loose ground, a comprehensive monitoring on the displacements of the tunnel is performed during construction. Based on the measured data and the proposed inversion method of elastic resistant coefficient, the elastic resistant coefficient is obtained. The method, analysis and conclusion of research can be valuable experience and reference for design, construction, supervision and further theoretical research on tunnel engineering under similar conditions.
2013, 21(1): 149-157.
The biggest advantage of drill test method is to obtain the rock mechanics characteristics such as deformation modulus and elastic modulus. They are the crucial parameters for engineering support design and engineering safety evaluation. This paper is based on a nuclear island construction project. It uses the boring elastic modulus method for rock mass mechanics characteristic. It finds that the method is good to reflect the rock mass structure characteristic and the stress-strain curve of test has a relative good regularity. The curve can be described as follows. In low pressure stage, the stress-strain curve is non-linear relation with a quick deformation. In medium pressure stage, it needs a certain pressure to force the drill wall and bearing plates of boring elastic modulus equipment to contact completely when the pressure increases and cracks close. In high pressure stage, the stress-strain curve is a linear relation. Meanwhile, with the influence of rock mass structure itself, the deformation modulus and elastic modulus vary at different depths. In a further study on the deformation modulus and elastic modulus at nuclear island, it is known that the anisotropy is not evident in granite ranging from weak weathering to fresh. However, some of the test section affected by cracks and joint cutting can show relative low rock mass modulus, bigger rock modulus ratio and stronger in anisotropy. Finally, this paper provides the rock mass modulus in weak weathering to fresh conditions as follows. At the weak weathering condition. The standard value of NS deformation modulus is 24.021.61GPa; the standard value of EW deformation modulus is 23.921.56GPa and the comprehensive value of deformation modulus is 23.971.10GPa. At the fresh condition, the standard value of NS elastic modulus is 45.152.58GPa; the standard value of EW elastic modulus is 44.252.57GPa and the comprehensive value of elastic modulus is 44.701.79GPa.
The biggest advantage of drill test method is to obtain the rock mechanics characteristics such as deformation modulus and elastic modulus. They are the crucial parameters for engineering support design and engineering safety evaluation. This paper is based on a nuclear island construction project. It uses the boring elastic modulus method for rock mass mechanics characteristic. It finds that the method is good to reflect the rock mass structure characteristic and the stress-strain curve of test has a relative good regularity. The curve can be described as follows. In low pressure stage, the stress-strain curve is non-linear relation with a quick deformation. In medium pressure stage, it needs a certain pressure to force the drill wall and bearing plates of boring elastic modulus equipment to contact completely when the pressure increases and cracks close. In high pressure stage, the stress-strain curve is a linear relation. Meanwhile, with the influence of rock mass structure itself, the deformation modulus and elastic modulus vary at different depths. In a further study on the deformation modulus and elastic modulus at nuclear island, it is known that the anisotropy is not evident in granite ranging from weak weathering to fresh. However, some of the test section affected by cracks and joint cutting can show relative low rock mass modulus, bigger rock modulus ratio and stronger in anisotropy. Finally, this paper provides the rock mass modulus in weak weathering to fresh conditions as follows. At the weak weathering condition. The standard value of NS deformation modulus is 24.021.61GPa; the standard value of EW deformation modulus is 23.921.56GPa and the comprehensive value of deformation modulus is 23.971.10GPa. At the fresh condition, the standard value of NS elastic modulus is 45.152.58GPa; the standard value of EW elastic modulus is 44.252.57GPa and the comprehensive value of elastic modulus is 44.701.79GPa.
2013, 21(1): 158-165.
This paper is about the typical geological units of surface sediments in Huaibei plain. In situ tests including screw plate tests, plate loading tests and static cone penetration tests are carried out in representative test work sites. Bearing capacity features of the calcareous concretion clay, recently deposited silt and silty sand are analyzed. The p-s curve characteristics of different soils from the screw plate test and determination method and range of bearing capacity are discussed. Their correlation and variation are analyzed compared with the data from static cone penetration tests and plate loading tests. The results show that bearing capacities of the clay, silty clay and silt are lower. The calcareous concretions in clay and silty sand have relatively higher bearing capacity and wide range of values. The degree of compaction is the main factor to determine the bearing capacity of silt and silty sand. The modified mechanical property characteristics of multiple cross-bedded foundation soils can be reflected better through the screw plate test. The strain control method can be adopted as a rapid, layered detection test method and its reliability is verified with the stress control method test. By linear fitting plate loading test results, the empirical formula for the screw plate test to determine bearing capacity of foundation in Huaibei Plain is given.
This paper is about the typical geological units of surface sediments in Huaibei plain. In situ tests including screw plate tests, plate loading tests and static cone penetration tests are carried out in representative test work sites. Bearing capacity features of the calcareous concretion clay, recently deposited silt and silty sand are analyzed. The p-s curve characteristics of different soils from the screw plate test and determination method and range of bearing capacity are discussed. Their correlation and variation are analyzed compared with the data from static cone penetration tests and plate loading tests. The results show that bearing capacities of the clay, silty clay and silt are lower. The calcareous concretions in clay and silty sand have relatively higher bearing capacity and wide range of values. The degree of compaction is the main factor to determine the bearing capacity of silt and silty sand. The modified mechanical property characteristics of multiple cross-bedded foundation soils can be reflected better through the screw plate test. The strain control method can be adopted as a rapid, layered detection test method and its reliability is verified with the stress control method test. By linear fitting plate loading test results, the empirical formula for the screw plate test to determine bearing capacity of foundation in Huaibei Plain is given.
2013, 21(1): 166-169.
This is a summary report for the 4th International Forum on Opto-electronic Sensor-based Monitoring in Geo-engineering(4th OSMG-2012).This forum was sponsored by Nanjing University, organized by Nanjing University High-tech Institute at Suzhou, and supported by National Science Foundation of China(NSFC) and other organizations. The forum shows the following four features in the recent years: (1)Theoretical researches have been enhanced and a series of fundamental research output have emerged.(2)More and more innovative sensors tailored for geo-engineering monitoring have been developed recently, which show unique benefits regarding accuracy, stability, reliability and integration ability.(3)the applications of distributed sensing technologies in safety monitoring of geo-hazards and geotechnical structures have been advocated extensively. Some monitoring systems have been established for specific projects.(4)the fully-distributed and qusai-distributed fiber optic sensing technologies have been introduced into the disciplines of hydraulic, transportation, fire protection, electric power, and national defense engineering. Standardization has been widely concerned. The future researches may focus on the following four aspects: (1)development of cost-effective demodulation techniques for fully-distributed fiber optic sensing technology; (2)development of special fiber optic sensors for geo-engineering and their field installation methods; (3)transmission and processing technologies of huge monitoring data from distributed fiber optic sensors; (4)early warning and stability assessment methods for geo-hazards and geotechnical structures based on distributed monitoring technologies.
This is a summary report for the 4th International Forum on Opto-electronic Sensor-based Monitoring in Geo-engineering(4th OSMG-2012).This forum was sponsored by Nanjing University, organized by Nanjing University High-tech Institute at Suzhou, and supported by National Science Foundation of China(NSFC) and other organizations. The forum shows the following four features in the recent years: (1)Theoretical researches have been enhanced and a series of fundamental research output have emerged.(2)More and more innovative sensors tailored for geo-engineering monitoring have been developed recently, which show unique benefits regarding accuracy, stability, reliability and integration ability.(3)the applications of distributed sensing technologies in safety monitoring of geo-hazards and geotechnical structures have been advocated extensively. Some monitoring systems have been established for specific projects.(4)the fully-distributed and qusai-distributed fiber optic sensing technologies have been introduced into the disciplines of hydraulic, transportation, fire protection, electric power, and national defense engineering. Standardization has been widely concerned. The future researches may focus on the following four aspects: (1)development of cost-effective demodulation techniques for fully-distributed fiber optic sensing technology; (2)development of special fiber optic sensors for geo-engineering and their field installation methods; (3)transmission and processing technologies of huge monitoring data from distributed fiber optic sensors; (4)early warning and stability assessment methods for geo-hazards and geotechnical structures based on distributed monitoring technologies.
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