| China is a well developed karst country, with the rapid development of water conservancy construction, often encounter dissolved limestone areas of hydraulic pressure tunnel construction problems such as poor karst geological phenomena and the existence of a hydraulic tunnel excavation pose a serious threat to operational safety. Through the karst areas in ensuring the construction of hydraulic tunnel fast smooth and safe operation at the same time, how to ensure the stability of surrounding rock is the hydraulic tunnel construction in karst areas that urgently need to resolve key technical issues.This article first by collecting a large number of documents at home and abroad, based on previous studies, the karst tunnel analysis summarizes the domestic and international rock cave gap morphology and distribution and the cause of the disaster caused by the tunnel and disasters, and to propose Karst tunnel analysis model.In the analysis model established based on the use of ANSYS10.0 finite element analysis software, caverns and gaps in the circular tunnel with gate vault above the lateral side walls and invert the bottom three conditions was calculated. According to finite element calculation of the following conclusions:(1) Top of the cave on the tunnel vault, and the vertical deformation of the dome can inhibit, to deformation when compared to non-cavity deformation has been reduced; tunnel side wall by the impact of horizontal deformation of the top cave increased when compared to non-cave.(2) At the bottom of the caves on tunnel vault sinking as the same cave has inhibitory effects, circular tunnel floor amount of vertical displacement is less than the amount of deformation without cave. Inside of the tunnel is at the bottom of the caves diameter varies with different effects: when the cave with diameter less than tunnel, tunnel effect on the bottom floor subject than no caves karst cave when there has been an increase in vertical direction deformation; when the cave diameter greater than tunnel, bottom vertical displacement less cave is reduced.(3) The impact of wall cave, tunnel vault sink, floor, on drums, and near cave side of the wall compared to the level of distortion and non-cave will increase. Cave side of the tunnel away from the horizontal deformation of the side walls will not cave when the deformation is less than.(4) When the tunnel is in the water pressure when the tunnel near cave side of radial deformation when compared with no cave, and it will increase the tunnel for the rest of the deformation of a slight decrease when no cave. According to the numerical simulation results presented by the water pressure tunnel near cave side deformation formula. |
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