Research On Multi Fields Coupling And Water Inflow Amount Prediction For Karst Water-Rich Tunnel

In the process of tunnel excavation in mountains, water influence is a main concern to surrounding rock in tunnel engineering field. In water-rich area, underground water can be a great influence to the stability of surrounding rock and prediction of water inflow amount. By prediction and controlling underground well, possibility of accidents in the process of tunnel excavation can be smaller and tunnel excavation process can be undertaken smoothly. Therefore, researching stress field, seepage field, displacement field coupling with each other, bringing up water inflow prediction method is of great importance to the safe construction of Karst and water-rick tunnel.Based on monitoring measurement and hydrological observation, accompanied by theory analysis, field experiment, field monitoring and numerical simulation methods, mechanism of seepage field changing to the rock stress field and displacement were analyzed. Furthermore, stress field, displacement and seepage field coupling was studied. Based on multi fields coupling, largest water inflow amount calculating method was brought up. Based on practical engineering project, multi methods were used in the prediction of water inflow amount. By comparing with water inflow amount get from field experiment, prediction methods behaved well. Moreover, GPR method was used in field experiment, and the range of loose circle under the influence of seepage water was obtained, and the effectiveness of GPR method was verified. Main research results of this thesis are like below:(1) On the basis of theoretical analysis, water balance method and two other methods to predict water inflow amount were used to predicted water inflow amount in Sanquan Tunnel. Based on field monitoring experiment, accuracy of prediction in different sections was analyzed, the results showed when there is underground water flowing into tunnel, underground water runoff numerical simulation method was better than the other two methods. The data also showed that the water inflow amount was mainly influenced by rainfall, which can prove that underground water runoff numerical simulation method and water balance method is reliable in prediction Karst water-rich tunnel. By comparing with data got from field experiment, methods to solve water inflow problem were brought up and can be a reference to tunnel engineering like this.(2) Based on field experiment, stress field and rock body strength can be influenced by underground water. The more underground water, the bigger influence to ground rock stress and displacement. Multi-point extensometer was used to measure the loose circle of surrounding rock, which can verify the accuracy of GPR result.(3) Based on numerical simulation method, surrounding rock's stress, displacement and plastic zone in multi fields coupling of Sanquan Tunnel was undertaken. The results showed seepage field can be a big influence to the stress, displacement and plastic. The results of numerical simulation method, theory explanation and field experiment study are almost the same, which can verify the accuracy of numerical simulation.