Study Of Ground Disturbance Caused By Shield Construction In Saturated Soil

With the increasing population of our country,the traffic in major cities is becoming more and more crowded,and the infrastructure construction is gradually improving.As one of the efficient transportation modes,subway has the advantages of saving land resources and less interference with other transportation modes.Therefore,subway rail transit has been built in many large and medium-sized cities.At present,the shield method is mostly used in the construction of subway.Although the shield method has many advantages,the shield machine itself will inevitably cause soil disturbance around the tunnel,and produce different soil deformation under different hydrogeological conditions,and endanger the underground pipeline and the ground environment in serious cases.Therefore,the shield method is used in the construction.It is necessary to study the settlement of soil.The main innovations and findings of this paper are as follows:(1)Using the analytical solution derived from Biot consolidation theory,the vertical displacement and pore water pressure of soil layer caused by shield construction are studied.According to the characteristics of interaction between cutterhead and soil during shield construction,the analytical formula of vertical displacement and pore water pressure of a point in three-dimensional soil caused by spoke cutterhead panel and cutterhead and cutterhead side of shield machine is derived.The total settlement formula and the total pore water pressure formula are obtained by introducing the vertical displacement of soil caused by other factors of shield construction,and the analysis is carried out by combining the engineering calculation example.(2)This paper studies the shield tunnel construction under the city road considering the road under the roadbed.through the introduction of the layer method,the homogeneous soil layer covered with different materials is equivalent to a homogeneous soil layer,combined with the expression of total vertical deformation and total pore water pressure to solve the problem.According to the engineering calculation example under the same condition of other conditions,through the calculation of six groups of different included angles between the shield axis and the highway axis,it is analyzed in the influence of angle factors on the settlement size,and draw some useful conclusions.(3)A three-dimensional model of shield driving process in saturated soil is established.The gap produced in the process of shield construction is simulated by equivalent layers.Considering the coupling effect of water and soil,the numerical simulation of soil deformation and pore water pressure caused by shield construction in a certain construction section of Hangzhou Metro Line 2 is carried out,and the vertical deformation of the ground surface and the pore water pressure field around the tunnel are analyzed.The equivalent layer modulus parameters are adjusted to simulate the shield construction under three different shield construction quality,and the influence of construction quality on soil settlement and pore water pressure is analyzed.