The Study On Stability And Control Measures Of Tunnel Surrounding Rock By The Nearby Karst Cave

Karst landform is widely distributed in South China,in recent years,with the developmentof highway construction in southwestern mountainous area,a mass of tunnels have beenconstructed, not a few tunnels have been caught in large or small karst disaster among thesetunnels. For this reason, study on stability and control measures of tunnel surrounding rock，and minimizing karst disasters bring tunnel construction potential safety hazard is of greatsignificance.The article concludes the common disasters during the tunnel construction inkarst areas,and analyzes some kinds of representative nearby cavities’influence on stability oftunnel surrounding rock by means of numerical simulation, finally gives control measures ofcommon karst disasters during tunnel construction,combines the engineering project toillustrate specific treatment measure in practical tunnel engineering. The main researches ofthe article are as follows:1. Introduce classification status of karst bases on the form of cavity, the way offilling,the characteristic of filling, dynamic change of water inflow, conclude the commonkarst disaster types during the tunnel construction in these areas.2. Utilize the simulation software of FLAC3D to analyze the stability of tunnelsurrounding rock in the cavities of different sizes in tunnel’s typical nearby location (such asthe lateral,the up and the down),and whether the cavites are filled with water and highpressure or not.Concretely analyze the impact on stress field, displacement field and plasticzone of surrounding rock with the cavity of different working conditions.And take advantageof shear failure theory to get the safe thickness between cavity and tunnel when the cavity isfiilled with water and has high pressure(the most harmful condition).3. Reinforce advance geology forecast during tunnel construction in karst areas, to givepriority to Geophysical prospecting method,use geological method to correct dynamically andverify the result by Advanced level drilling method;In allusion to the the cavity detected withdifferent sizes, packing medium and whether its inwall is filled with water and high pressureor not, wo should adopt corresponding and reasonable treatment measures,and combine theuncovering cavities of Xiejiatong Tunnel, analyze the comprehensive treatment measure ofgiant cavity.