Study On The Characteristics Of Seepage Field And Water Pressure On Tunnel Lining In Karst Ground

With the implementation of the China's strategy to develop its western regions and the rapid development of traffic cause, it is inevitable to build tunnels in the Karst areas.In recent years, lots of engineering problems caused by the Karst water bursting and burst mud occurred in tunnel construction, which brought hazard to tunnel construction and operation. Rational determination of the hydraulic pressure on the line is the key factor in supporting structure design of Karst tunnel. However there is no systematic research on the distribution rule of seepage field for Karst tunnel by blocking ground water and limiting discharge. Based on the Karst tunnels of YiChang-WanZhou railway, the distribution rule of seepage field, the stress characteristic of lining structure under the combined action of stress and seepage field and the effect of grouting control factors on the distribution of seepage field were studied in this thesis through theoretical analysis, numerical simulation and model test. The main contents and achievements of this thesis are listed as following:(1)The interaction of the stress and the seepage field was analyzed and their mutual influence way in the crevasse rock mass was obtained. Using analysis method to research the seepage field distribution rule of the steady flow in the high hydraulic pressure mountain tunnel we get the distribution of seepage field in karst area under special geological conditions.(2) By studying the principle of similarity theory and model test, we derived the similarity criteria under coupling field of stress and stress.Using the model test system developed by tunnel and underground engineering test center,bringing in fiber Bragg grating strain-testing system and taking Qiyueshan tunnel as prototype, we do research on water pressure distribution law on the back of lining and out of grouting circle under the way of whole plugging and limiting discharge respectively, and get the reduction law of water pressure with grouting circle.(3)Depending on accurate strain data collected by fiber grating, we draw a con clusion of the deformation feature and intermediate principal stress of lining structure under the combined action of stress and seepage field. Combined with the features of similarity principle and model test, we conclude the similarity criteria of return of model test data, calculate stress and internal force of original runnel lining structure,and assessment on the safety of prototype structure.(4)By means of numerical method and depending on three-dimensional seepage finite element software,we do research on influence law of seepage field distribution of tunnel surrounding rock by grouting controlling factors and the reduction law of lining water pressure on different water discharge.