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Editor Work1999 Vol. 7, No. 4
Previous Issue
1999, 7(4): 291-297.
Abstract
The excavation of 76m long Dabeiyao Metro tunnel had to be stopped because of quicksand at its roof. A high cost freezing scheme was suggested to use after some researches and tests for more than one year. Hereafter the problem was studied by the authors from geoengineering view point. The geological environment and engineering geological properties of saturated silt and fine sand roof are analyzed in this paper. A new microcement grouting technique is developed to stabilize the Dabeiyiao tunnel roof at the quicksand and quicksand disturbed section. Steel tube grouting is used to stabilize the roof at the undisturbed section. monitoring data indicate that the measures are effective for the roof stability control.
The excavation of 76m long Dabeiyao Metro tunnel had to be stopped because of quicksand at its roof. A high cost freezing scheme was suggested to use after some researches and tests for more than one year. Hereafter the problem was studied by the authors from geoengineering view point. The geological environment and engineering geological properties of saturated silt and fine sand roof are analyzed in this paper. A new microcement grouting technique is developed to stabilize the Dabeiyiao tunnel roof at the quicksand and quicksand disturbed section. Steel tube grouting is used to stabilize the roof at the undisturbed section. monitoring data indicate that the measures are effective for the roof stability control.
1999, 7(4): 298-302.
Because the three dimensional geostress in crustal rockmass exists often in the pattern of compressive stress, the weak layerzone in rockmass bears normal compressive stress caused by the three dimensional geostress (natural confining pressure). In this paper, the authors study the engineering properties (physical mechanical properties) of argillaceous material in weak layerzone under the naturally confining pressure, and fine the well correlation between the engineering properties of argillaceous material at the condition of natural compression and its natural confining pressure, and then point out the existing problems in present studies on engineering properties of weak layerzone in neglecting natural geostress.
Because the three dimensional geostress in crustal rockmass exists often in the pattern of compressive stress, the weak layerzone in rockmass bears normal compressive stress caused by the three dimensional geostress (natural confining pressure). In this paper, the authors study the engineering properties (physical mechanical properties) of argillaceous material in weak layerzone under the naturally confining pressure, and fine the well correlation between the engineering properties of argillaceous material at the condition of natural compression and its natural confining pressure, and then point out the existing problems in present studies on engineering properties of weak layerzone in neglecting natural geostress.
1999, 7(4): 303-309.
The interaction between soil mass deformation and pore water pressure during subsidence by mining is studied in this paper by theoretical analysis,laboratory tests, and in situ measurements. The results show that the generation and dissipation of super static pore pressure are caused by the variations of stress and deformation in soil mass along with the mining progress. Compressive or expansive deformation occurs and grows with time of mining. The compression and expansion may be superimposed on each other in different parts of soil mass and sometimes on the subsidence caused by drawdown of groundwater level in bottom aquifers. The study reveals a mechanism of subsidence by mining in mines with thick water bearing soil layers and is of significance in subsidence prediction and mining under water body.
The interaction between soil mass deformation and pore water pressure during subsidence by mining is studied in this paper by theoretical analysis,laboratory tests, and in situ measurements. The results show that the generation and dissipation of super static pore pressure are caused by the variations of stress and deformation in soil mass along with the mining progress. Compressive or expansive deformation occurs and grows with time of mining. The compression and expansion may be superimposed on each other in different parts of soil mass and sometimes on the subsidence caused by drawdown of groundwater level in bottom aquifers. The study reveals a mechanism of subsidence by mining in mines with thick water bearing soil layers and is of significance in subsidence prediction and mining under water body.
1999, 7(4): 310-314.
According to the Bettis reciprocal energy theorem, energy damage evolution equation of jointed rockmass, generalized normal flow rule, and consistent condition of plastic damage, A 3 D constitutive model for energy damage of jointed rockmass is firstly constructed in this paper. Then a 3 D Nonlinear FEM Computation program about the constitutive model has been programmed, Finally we apply the program to underground power house of XILUODU hydroelectric station to Carry out Stability analysis under excavation and get some satisfactory computation results.
According to the Bettis reciprocal energy theorem, energy damage evolution equation of jointed rockmass, generalized normal flow rule, and consistent condition of plastic damage, A 3 D constitutive model for energy damage of jointed rockmass is firstly constructed in this paper. Then a 3 D Nonlinear FEM Computation program about the constitutive model has been programmed, Finally we apply the program to underground power house of XILUODU hydroelectric station to Carry out Stability analysis under excavation and get some satisfactory computation results.
1999, 7(4): 315-320.
This paper describes an in situ measurement method of hydraulic features of rocks (including water pressure, water conductivity, discharge, high water conductivity fracture zone).Taking Taiyuan Dongshan Coal Mine as an example, in situ measurement method was used in determining the hydraulic features of base rocks stratum of carboniferous Taiyuan and Benxi groups. The obtained results are described in detail here. The research is of significance in coal mining above confined aquifer.
This paper describes an in situ measurement method of hydraulic features of rocks (including water pressure, water conductivity, discharge, high water conductivity fracture zone).Taking Taiyuan Dongshan Coal Mine as an example, in situ measurement method was used in determining the hydraulic features of base rocks stratum of carboniferous Taiyuan and Benxi groups. The obtained results are described in detail here. The research is of significance in coal mining above confined aquifer.
1999, 7(4): 321-326.
The structural stability indexes reflecting the concrete stable conditions of surrounding rocks of gallery influenced by overhead mining are set up and their weights are determined from field measurement data. A sub classification pattern of the structural stability is obtained by using ISODATA fuzzy cluster analysis method. A practical scheme of stractural stability classification is also put forward. It can be used in stability prediction and support design of gallery influenced by overhead mining.
The structural stability indexes reflecting the concrete stable conditions of surrounding rocks of gallery influenced by overhead mining are set up and their weights are determined from field measurement data. A sub classification pattern of the structural stability is obtained by using ISODATA fuzzy cluster analysis method. A practical scheme of stractural stability classification is also put forward. It can be used in stability prediction and support design of gallery influenced by overhead mining.
1999, 7(4): 327-331.
A concept of cement loose composite pile is proposed in this paper, that is a pile consists of two parts, the upper is a cement pile and the lower is loose material pile, so that the defect caused by low bearing capacify of loose material pile can be removed by this method. The concept of bearing of cement loose composite pile is studied and a calculation method and a formula of the bearing capacity, settlement, and critical lengh of the pile are suggested. At last, the first engineering case is introduced.
A concept of cement loose composite pile is proposed in this paper, that is a pile consists of two parts, the upper is a cement pile and the lower is loose material pile, so that the defect caused by low bearing capacify of loose material pile can be removed by this method. The concept of bearing of cement loose composite pile is studied and a calculation method and a formula of the bearing capacity, settlement, and critical lengh of the pile are suggested. At last, the first engineering case is introduced.
1999, 7(4): 332-336.
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Abstract This paper deals with the size effects of mechanical properties of rockmasses. A mechanical description of the REV related to the elastic modulus of jointed rockmasses is proposed, and an expression of the REV based on the central limit theorem is suggested. The study shows that the REV can be used to reflect the size effect of mechanical properties of rockmasses. The result obtained in this work can provide a new way how to appropriately select the mechanical parameters of jointed rockmasses.
Abstract This paper deals with the size effects of mechanical properties of rockmasses. A mechanical description of the REV related to the elastic modulus of jointed rockmasses is proposed, and an expression of the REV based on the central limit theorem is suggested. The study shows that the REV can be used to reflect the size effect of mechanical properties of rockmasses. The result obtained in this work can provide a new way how to appropriately select the mechanical parameters of jointed rockmasses.
1999, 7(4): 337-343.
The basic principle of orthogonal finite element method for experimental analysis is introduced and applied to the optimization of underground engineering design schemes. Manyuseful conclusions available to engineering is drawn. By analyzing the optimization of blot spraying parameters of large underground openings and selection of mining schemes of underground stope it is concluded that this method can be tentatively applied to optimization of engineering design schemes in underground engineering.
The basic principle of orthogonal finite element method for experimental analysis is introduced and applied to the optimization of underground engineering design schemes. Manyuseful conclusions available to engineering is drawn. By analyzing the optimization of blot spraying parameters of large underground openings and selection of mining schemes of underground stope it is concluded that this method can be tentatively applied to optimization of engineering design schemes in underground engineering.
1999, 7(4): 344-348.
Ground Penetrating Radar (GPR) is a new geophysical tool which generates super high frequency pulse electromagnetic wave used to detecting the distribution of underground media. The attenuation behaviors of GPR pulse wave with wide frequency band and high frequency in underground media are very complicated process courses. In this paper, from Maxwells equations, the attenuation behaviors of GPR pulse electromagnetic wave propagation in heterogeneous medium are systematically studied and the obtained results are very useful for knowing the propagation mechanism of GPR pulse electromagnetic wave in underground hetorogeneous medium.
Ground Penetrating Radar (GPR) is a new geophysical tool which generates super high frequency pulse electromagnetic wave used to detecting the distribution of underground media. The attenuation behaviors of GPR pulse wave with wide frequency band and high frequency in underground media are very complicated process courses. In this paper, from Maxwells equations, the attenuation behaviors of GPR pulse electromagnetic wave propagation in heterogeneous medium are systematically studied and the obtained results are very useful for knowing the propagation mechanism of GPR pulse electromagnetic wave in underground hetorogeneous medium.
1999, 7(4): 349-354.
The shiplock of the Three Gorges Project is the largest one in the world. Faults and Joints in rockmass are more developed of in the project area and affect the mechanical properties of rockmass. For study the distribution character of joint dips, an advanced Bayes method is used to infer the probability distribution function(PDF)of joint dips parameters in rockmass in the paper. Based on 3373 Joints in the rockmass for the permanent shiplock of the Three Gorges Project, the PDF of dip parameters are analysed by using advanced Bayes method and the errorstested are in permissible limit.
The shiplock of the Three Gorges Project is the largest one in the world. Faults and Joints in rockmass are more developed of in the project area and affect the mechanical properties of rockmass. For study the distribution character of joint dips, an advanced Bayes method is used to infer the probability distribution function(PDF)of joint dips parameters in rockmass in the paper. Based on 3373 Joints in the rockmass for the permanent shiplock of the Three Gorges Project, the PDF of dip parameters are analysed by using advanced Bayes method and the errorstested are in permissible limit.
1999, 7(4): 355-360.
There are large amount of data from many monitor sites of a large monitor system on a large scale slope. A traditional database system is difficult to visually inquire and analyze these monitor data. The authors developed a visual inquiry and analysis system for the monitor information by using the object oriented programming language Visual Basic and the object oriented database management development system Access based on Window Operation System. In this paper, taking the shiplock slope of Wuqiangxi Hydropower Station as an example, a programming of the system and functions of program are described.
There are large amount of data from many monitor sites of a large monitor system on a large scale slope. A traditional database system is difficult to visually inquire and analyze these monitor data. The authors developed a visual inquiry and analysis system for the monitor information by using the object oriented programming language Visual Basic and the object oriented database management development system Access based on Window Operation System. In this paper, taking the shiplock slope of Wuqiangxi Hydropower Station as an example, a programming of the system and functions of program are described.
1999, 7(4): 361-365.
In this paper, the authors simulate the bolting effects on the stability of jointed rockmass by dispersive element method (DEM). The results show that it is beneficial to improve the stability of surrounding rockmass by bolt reinforce as quickly as possible after shaping the gate. Also, there are obvious relations or synergetic character between deformation and fracture of the different parts of gate. We must reinforce the surrounding rockmass systematically.
In this paper, the authors simulate the bolting effects on the stability of jointed rockmass by dispersive element method (DEM). The results show that it is beneficial to improve the stability of surrounding rockmass by bolt reinforce as quickly as possible after shaping the gate. Also, there are obvious relations or synergetic character between deformation and fracture of the different parts of gate. We must reinforce the surrounding rockmass systematically.
1999, 7(4): 366-371.
Calcareous sand is a kind of easily crushed granular materials. Based on analyzing the mechanism of grain breakage, the authors establishe a crushing energy equation coupling crushing with dilation. It is proved that the relationship bet ween B r and 1, W p and W B is confirmed by the experiments, and bence the evaluation index and energy equation for calcareous sand crushing are set.
Calcareous sand is a kind of easily crushed granular materials. Based on analyzing the mechanism of grain breakage, the authors establishe a crushing energy equation coupling crushing with dilation. It is proved that the relationship bet ween B r and 1, W p and W B is confirmed by the experiments, and bence the evaluation index and energy equation for calcareous sand crushing are set.
1999, 7(4): 372-374.
Combining with practice of engineering construction, a study on the mechanism of project character effect of expansive soil mixed with lime, on engineering of of Nanyang expansive soil was performed, especially, a comparative test of lime soil 2:8 pad and original expansive soil was conducted.
Combining with practice of engineering construction, a study on the mechanism of project character effect of expansive soil mixed with lime, on engineering of of Nanyang expansive soil was performed, especially, a comparative test of lime soil 2:8 pad and original expansive soil was conducted.
1999, 7(4): 375-379.
Based on the principal law of seepage flow, considering the possibility of field test, a new field test method is proposed in this paper for determining the permeability parameters of gently dipping structural face or discontinuity. Firstly, a formula of the permeability parameters of gently dipping is deduced. Secondly, a simple water injection test was carried out in the hole penetrating typical structural faces or discontinuities by pneumatic drilling, then the permeability parameters of them were obtained. As an illustrative example, the Xiluodu Hydropower Station is presented and discussed.
Based on the principal law of seepage flow, considering the possibility of field test, a new field test method is proposed in this paper for determining the permeability parameters of gently dipping structural face or discontinuity. Firstly, a formula of the permeability parameters of gently dipping is deduced. Secondly, a simple water injection test was carried out in the hole penetrating typical structural faces or discontinuities by pneumatic drilling, then the permeability parameters of them were obtained. As an illustrative example, the Xiluodu Hydropower Station is presented and discussed.
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