Study On Rock Mass Stability For Lianyungang Road Tunnel

With the rapid development of the underground structure, the geological conditions have become an important part of underground project design and construction. But,due to the complexity and unpredicatable of geological conditions in underground engineering, and the limited ways of geological investigation,it is difficult to get the detailed date of geology,rock parameters and load parameters in the design phase. So, in the constructing tunnel, the geological workers need to fixed the design parameters and adjust the construction program, according to the results of the site geological condition, geological prediction and monitoring.Lianyungang road tunnel as the research object in this paper, the main contents and results are as follows:(1) Analysis the geological structure of the tunnel and geological survey, obtained the main factor to affect the security and stability of the tunnel is the weak and sensitive interface(2) Based on the geological survey in the field, obtained the advantage orientation of fractures in through statistical analysis of structure the tunnel. Through geological survey, there are NE, NW two sets of steep fractures of rock mass in the tunnel region.(3) Based on the field geological survey, suing the BQ method and Q system to evaluate quality of the tunnel rock mass. This paper takes a part of IV class rock mass an the research object, through qualitative assessment,BQ evaluation and Q evaluation,evaluated the rock quality is good andâ…¢grade, it is higher than the design phase, and design optimization for the rock support system.(4) Research the main failure mode of the surrounding rock in the tunnel through analyzing the relation of different structure. There are three main failure modes in the tunnel:â‘ wedge failure;â‘¡layer stripping failure;â‘¢the adverse combination of joints, soft interlayer and the excavation interface.(5) Based on the geological survey of Lianyungang Yuntaishan tunnel, using Finite element method to analysis the stability of the surrounding rock in the tunnel vault where there is soft interlayer.(6) Based on using geological survey of tunnel faces, geological radar and TSP to predict the geological conditions ahead of the tunnel faces, to provide the basis for the tunnel construction safety. Predictions are consistent with the actual situation of the working faces.(7) Through monitoring and measuring to the typical cross section, mastered the dynamic mechanical and stability of the surrounding rock during the construction support, to provide the basis information for evaluating and modifying the parameters of the tunnel support,and determining the construction procedure, to ensure the safety of the tunnel construction. Based on the feedback of the monitoring results, it is overall better of the surrounding rock, and the ways of excavation and support and construction organization are feasible.