GEOTECHNICAL ENGINEERING PROBLEMS IN FUZHOU SUBWAY CONSTRUCTION

Due to the complexity of engineering geological conditions and particularity of tunnel projects in Fuzhou Basin,the corresponding environmental geotechnical problems are emerged in the process of construction for Fuzhou rail transit. The main environmental geotechnical engineering problems are: (1)the confined aquifer within the scope of tunneling boring: The water-bearing capacity and hydraulic conductivity of confined aquifer are strong. As the excavation is deep,the influences on lower confined water must be considered,so that inrush of foundation pit may be avoided. The gravel pebble bed is directly covered on the hot water of bedrock fissure,and it is directly supplied and conducted by high-temperature hot water at the hot water structural belt. The issues,whether the construction of underground rail transit brings impact on geothermal field and what influence does geothermy bring to rail transit,need to be further studied.(2)Large deformation and low intensity of soft soils lead to instability of foundation and damage of the soil structure strength.(3)Deep and large excavation for foundation pit may cause the disasters. The excavation for foundation pit is easy to bring the problems,such as slump,mudflow,water inrush,surface subsidence,etc. ,so the effective preventive measures should be adopted to avoid the impact on engineering safety and surrounding environment. For these environmental geotechnical problems,new technologies for investigation shall be strengthened to find out geological conditions of the geotechnical engineering at building site; the ground freezing method and technology of pile underpinning shall be introduced for the construction; the new technologies,which are suitable for geotechnical conditions in the region,shall be developed and adopted,such as new piles,new water-seal,ground-water lowering measures and other foundation pit support technologies as well as new technology for information construction.