Study On The Influence By Karst On The Stability Of Surrounding Rock In Span And Neighborhood Tunnel

In this paper, taking chongqing shuangbei tunnel project as a background,according to the tunnel of the actual section size, surrounding rocks and supportingmaterial parameters and excavation method, use the finite element software ANSYSsimulation in the karst area the construction process of small spacing tunnel, andanalyses the following three problems:①By finite element software ANSYS to different size, different position of thecave who strata sandwich rock in the small spacing tunnel and double hole theconstruction process of the two dimension numerical simulation analysis, analyses withthe different size and position of karst cave, and the change rule of displacement field,stress field, plastic zone in the double hole surrounding rock.②By establishing three dimension finite element model, analyses the differentsize, different positions of karst cave distribute on the existing tunnel top, differentinterval of double line tunnel excavation on the influence law of the surrounding rock’sstability in the existing tunnel. From three dimension analysis results indicated that,when interval of the two tunnel arrive to a times, the karst cave existence or not, tomultiple track of tunnel excavation has caused the change of the stability of surroundingrock tunnel around basic no effect. For the double line tunnel excavation caused thechange of the stability of surrounding rock tunnel had no effect on the basic.③By establishing three dimension finite element model, analyses the differentsize, different position of the cave distribution in the existing tunnel bottom, differentinterval from the double line tunnel excavation on the influence law of the surroundingrock’s stability. From three dimension analysis indicated that, karst cave distribution intunnel bottom,the stratum between the tunnel and karst cave are in tensile condition,therefore, in this case we need to groute to the karst cave.