Study On Surrounding Rock Stability Around Tunnel Entrance In High Slope And Rock Stack Area

With the development of society and economy, the investment of infrastructure construction is greatly enlarged. As an important part of infrastructural construction of the traffic, the application of tunnel is more and more . A lot of railway and highway tunnels are built continuously. But, the tunnel is closely related to the slope, specially the highway mountain tunnel. because its span is large and the construction craft is complex , The coast, peeling off and dilapidation, are easily induced at the entrance of the tunnel. In the mountain and hill areas, because of being subjected to the geography condition, the tunnel entrance position sometimes has to be chosen at the high slope and rock heap area. With the unloading action, the possibly insecure slope may lose stability with the main form of coast and dilapidation, then endanger the structure's safety. Therefore, it is very important to do some researches on the stability of tunnel slope.By considering the influence of various factor , 2-D elastic-plastic model is built, the influence on the tunnel slope in different excavating and entering tunnel methods are calculated and analyzed in the paper. The slope's law of stress distributed, distortion, and destruction are studied. At the same time, The current measure for depending the tunnel slope is concluded. Then the basic factor influencing the tunnel slope stability is given, the destroyed theory of the tunnel slope is studied, and the basic destroyed way is enumerated. The paper analyzed and discussed the method to judge slope's stability of the rock tunnel, and the control technique of the tunnel entrance to some certain is studied.Based on the LINGGANGYAN TUNNEL'S design and construction information, The paper made use of locale survey and numerical simulation, qualitative analysis and quantitative analysis , aim at a series of technique measure about backfilling the cement soil, changing bevel to right-angle, backfill first to excavating behind, building uncovered tunnel as underground one, grouting reinforcement, etc, studied the stability of the high slope at tunnel entrance by finite element methods. After synthetically balancing technique, economy, safety, quality, and society effect, it should provide some important experience and theories gist to optimize the similar engineering.