Comparison Of Construction Method Of Shallow Buried Channel In The Water-enriched Cobble Ground And Numerical Analysis

With the intensification of the densest urban population and the traffic pressure increasing sharply on the ground,it is the inevitable trend of the development of modern city that constructing the subway.However,in the prosperous city,building the subway should not only consider the effect of the surrounding environment but also consider attracting traffic.So,it is also very important to design the passageway of subway,which is the only channel connect underground with the ground and viewed as a "node" of the city;its appearance not only accords with the city's overall layout and the long term planning of the urban construction in the appearance,but also it must be very good to attract traffic for the late more economic benefits of the subway's operation,so,there are a lot of passageways which across the city road about the layout of the urban subway passageway.However,in some urban roads that can't be closed to traffic,only studying what can not effect on the surrounding environment in the construction method.This paper relies on the construction of the NO.1 passageway of the B subway station of Changsha Metro Line A.comparing and selecting the best construction scheme of the channel of the NO.1 passageway of the B subway station by using the Analytic Hierarchy Process and Numerical Simulation Analysis to study.The main work and conclusions of this article are as follows:1?According to the basic characteristics of the subway entrance,to be selected using the Opencast Method,Shallow Mining Method and Pipe Jacking Construction as three alternative construction scheme;then building the indexes of the scheme's evaluation system in the aspect of the economic,technology,safety and environment by using Analytic Hierarchy Process,and using the 1-9 scale method for digital scoring to express the importance of each evaluation indexes by experts and experienced practitioners;finally determining the shallow mining method is the best method by applying Analytic Hierarchy Process.2?Aiming at the shallow mining method for construction,taking into account the characteristics of underground construction and environmental impact on the surrounding geological conditions,identified two alternative shallow excavation method step method and CRD method;under the same conditions,then applying Midas GTS to simulate and analyze the channel excavation with these construction methods;Through the simulation results,analyzing the stress-strain value,displacem-ent curves of monitoring points and size of the internal force of lining to select the best construction scheme;finally obtained that the CRD method was the best and the most consistent with the truth.3?Through previous comparison results,and combining theoretical calculations and engineering analogy method,determining construction program design for CRD excavation channel.Then,simulating the process of CRD excavation channel,and analyzing of the distribution state of the stress and plastic district,the different effect of excavating ground settlement and stress change of supporting structure,meanwhile,summarizing what impact on the soil around the channel cross-section when excavating the channel and the force characteristics of initial support structures in the supporting process etc.