Analysis on Influence of Hidden Water-rich Karst Cave on Stability of Tunnel Surrounding Rock:Taking Yunnan Yunpan Mountain Tunnel as an Example
In order to study the stability of surrounding rock caused by hidden water-filled caverns in the excavation process of karst tunnels,relying on the Yingpan Mountain Tunnel Project in Yunnan,taking the size of the cavern,the water pressure and the net dis-tance between the tunnel and the three factors as the object of study,combining the new three-dimensional radar detection technology,and numerical simulation using PLAXIS 3D,to analyze the change rules of the tunnel's various monitoring points of the displacement,the stress field,and the influence of the effect of the change rules.The results of the study show that:tunnel excavation will cause changes in the stress field,the surrounding rock at the tunnel arch and arch waist is dominated by compressive stress,and the sur-rounding rock under the tunnel elevation arch is dominated by tensile stress,and the changes in the stress of each part of the tunnel are also the main reasons for the expansion of the surrounding rock into the tunnel.Under a single variable,the changes in displacement and stress are greatest when the radius of the tunnel is 5 m,and the changes in displacement and stress are most significant when the water pressure in the cavern is increased to 500 kN/m2.When the clear distance between the cavity and the tunnel reaches 3 m,the change of displacement and stress field is especially obvious.There are differences in the sensitivity of the surrounding rock stability to the size of the cavern,water pressure,and the clear distance between the tunnel and the cavern,with the size of the clear distance be-tween the tunnel and the cavern＞water pressure in the cavern＞size of the cavern,which can be used as a reference for the safety of the construction of similar projects.
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