The Study Of The Karst Loose Deposits Effect On The Stability Of Surrounding Rock Of Hydraulic Tunnel

The influence of poor karst geology on hydraulic tunnel is mainly reflected in the loose accumulation of karst,the deformation,collapse and instability of hydraulic tunnel caused by karst cavities and karst water.As far as the influence of karst loose deposits on underground engineering,there is no quantitative theory and related experimental research.This paper combines the existing field investigation data and theoretical research experience.A general model of vertical circular arch hydraulic tunnel with different volume sizes and different distances is established,and finite element analysis method is used.Study on the effect of Karst loose deposits on hydraulic Engineering in excavation,Operation and other stages with the help of ABAQUS Analysis Software The influence law of tunnel surrounding rock stability and its action mechanism are analyzed.The main research results and understanding are as follows:(1)According to the statistical analysis of the spatial distribution of karst caves and the reference data of the distribution patterns and characteristics of karst loose deposits in various karst areas,through the analysis of the action mode of the karst loose accumulation on the surrounding rock of the hydraulic tunnel,it is finally determined that the rock dissolving loose deposits in the case of non Unicom influence the surrounding rock of the hydraulic tunnel.Stability analysis plan and ABAQUS numerical simulation method.(2)Under the influence of the top karst loose accumulation,the vertical deformation of the tunnel vault and the arch bottom is restrained to a certain extent,and the deformation amount is reduced when the deformation amount is less than that without karst loose accumulation,and the lateral wall of the tunnel is affected by the top karst cave,and the deformation of the tunnel is more than that of the non karst cave..(3)Under the influence of side wall karst loose accumulation,the vertical deformation of the tunnel and the horizontal deformation of the tunnel wall will increase compared with the loose deposits.The displacement of the right wall of the loose accumulation of karst is obviously greater than that of the left wall,which increases with the increase of the thickness of the karst loose deposit,and decreases with the increase of the thickness of the rock wall.(4)Under the influence of the 45 degree of vault,the vertical displacement of the surrounding rock is similar to the karst loose accumulation in the top.The lateral wall of the horizontal displacement is larger than the left side wall without karst loose accumulation,which decreases with the size of the karst loose deposits increasing,and increases with the increase of the thickness of the rock wall.(5)By summarizing the influence of different azimuth karst loose deposits on the influence of surrounding rock and further analyzing its mechanism of action,it is believed that the existence of karst loose deposits has destroyed the influence of tunnel surrounding rock integrity on the other side of the tunnel’s high span ratio,and the influence of karst loose accumulation on the height span ratio of the tunnel in different positions and its circumference.The relationship between rock safety is analyzed and explained.