Study On SRD Method Of Dongxing Tunnel On Jinlin-tumen-hunchun High-speed Railway Under Swelling Rock Field

In recent years, with the rapid development of high-speed railway, the constructionand maintenance of railway tunnel in complicated geological conditions become morefrequently. During this period, it is often seen engineering problems induced by swellingsoft rock. According to statistics, tunnel engineering in more than40countries andregions of the world all suffered swelling rock problem to various extent, which causeda big economic loss. In our country, this problem mainly appears in Guangxi, Yunnan,Henan, Hubei, Sichuan, Shaanxi, Hebei, Anhui, Jiangsu, Jilin and so on. Therefore, it isvery meaningful to carry out the research of tunnel excavation under specialgeotechnical environment and put forward fast excavation and supporting methodsuitable for tunnel construction under swelling soft rock field.Aiming at the excavation problem of Dongxing tunnel in Jilin-Tumen-Hunchuirailway at swelling rock site, this thesis analyses the engineering geology andhydrogeology data, obtains stratigraphic distribution and main physical and mechanicalparameters. At the same time, this thesis studies the free swelling ratio test results ofswelling rock at different depth but the same location and different locations but thesame depth of the Dongxing tunnel field, and gets the distribution condition of the field.In addition, it elaborates the existed construction method and the serious engineeringproblems of Dongxing tunnel, and then proposes a new tunnel excavation method,called soil reserved diaphragm method (SRD method), which is suit for swelling rockfield. Then, it compares the cross diaphragm method and the soil reserved diaphragmmethod using two-dimensional and three-dimensional finite element models, andanalyses the main construction parameters of SRD method. The details are presented asfollows:(1) Establish two-dimensional finite element model of CRD method and SRDmethod. Make comparative analysis of the effects of different excavation methods onground settlement, crown settlement, horizontal converge, plastic zone distribution andinternal force of support structure etc.(2) Establish two-dimensional finite element models for the SRD method and makeanalysis of the influence of different parameters on the ground settlement, crownsettlement and horizontal convergence by changing the construction step, the soilcolumn width, the soil column curvature etc. Besides, Establish three-dimensional finiteelement models with three types of step excavation length, such as6m,12m and15m,and make analysis of the specific impact on the leading face, the lagging face, thelongitudinal settlement and crown settlement. And then provides the optimal valuesrange of different construction parameters for SRD method. On the basis of research, it introduces the construction state of SRD method, andverifies the feasibility and advantages of SRD method in tunnel excavation problems,which provides reference for the tunnel excavation in swelling rock field.