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Analysis on Deformation and Failure Characteristics of Surrounding Rock in Horizontal Layered Tunnels under High Crustal Stress Based on 3DEC Simulation
(1. School of Highway, Chang'an University, Xi′an 710064; 2. Shaanxi Provincial Key Laboratory of Highway Bridges and Tunnels,Chang′an University, Xi′an 710064; 3. The First Engineering Co., Ltd. of China Railway Beijing Engineering Group, Xi′an 710119)
Abstract In order to thoroughly study the characteristics of deformation failure in surrounding rock of horizontal layered tunnels under high crustal stress environment, the crustal stress test results and the deformation failure of surrounding rock were analyzed based on engineering background of Yunnan Zhaotong-Leshan Expressway Jiaoding Tunnel. The 3D discrete element (3DEC) numerical simulation method was adopted to study the deformation failure laws of surrounding rock under the conditions of different rock thickness d, crustal stress level s and lateral pressure coefficient k. Moreover, the stress characteristics and deformation failure mechanism of surrounding rock of horizontal layered tunnel were discussed as well. The results show: the deformation of horizontal layered surrounding rock is symmetrically distributed along the central axis of the tunnel. The displacement of surrounding rock is the largest where the joint direction is tangent to the tunnel contour, but is the smallest where the joint direction is orthogonal to the tunnel contour; With the increase of layer thickness, the displacement of surrounding rock of the tunnel decreases gradually. The displacement changes faster when the thickness is 0~0.3 m, slows down when the thickness exceeds 0.3 m, and basically tends to be stable when the layer thickness reaches 3.0 m; The displacement of tunnel surrounding rock increases gradually with the increase of crustal stress, and the change rate remains stable; The displacement of tunnel surrounding rock increases gradually as function of lateral pressure coefficient, and the displacement change is the most significant at the arch waist. In the crustal stress environment, severe compression deformation may occur even if rock strength is great, in case the layered joints of the surrounding rock are developed, which shows the characteristics of great deformation in soft rock.
Abstract：
In order to thoroughly study the characteristics of deformation failure in surrounding rock of horizontal layered tunnels under high crustal stress environment, the crustal stress test results and the deformation failure of surrounding rock were analyzed based on engineering background of Yunnan Zhaotong-Leshan Expressway Jiaoding Tunnel. The 3D discrete element (3DEC) numerical simulation method was adopted to study the deformation failure laws of surrounding rock under the conditions of different rock thickness d, crustal stress level s and lateral pressure coefficient k. Moreover, the stress characteristics and deformation failure mechanism of surrounding rock of horizontal layered tunnel were discussed as well. The results show: the deformation of horizontal layered surrounding rock is symmetrically distributed along the central axis of the tunnel. The displacement of surrounding rock is the largest where the joint direction is tangent to the tunnel contour, but is the smallest where the joint direction is orthogonal to the tunnel contour; With the increase of layer thickness, the displacement of surrounding rock of the tunnel decreases gradually. The displacement changes faster when the thickness is 0~0.3 m, slows down when the thickness exceeds 0.3 m, and basically tends to be stable when the layer thickness reaches 3.0 m; The displacement of tunnel surrounding rock increases gradually with the increase of crustal stress, and the change rate remains stable; The displacement of tunnel surrounding rock increases gradually as function of lateral pressure coefficient, and the displacement change is the most significant at the arch waist. In the crustal stress environment, severe compression deformation may occur even if rock strength is great, in case the layered joints of the surrounding rock are developed, which shows the characteristics of great deformation in soft rock.
WANG Yaqiong1,
2 YANG Qiang1,
2 PAN Hongwei3 GAO Qidong1 etc
.Analysis on Deformation and Failure Characteristics of Surrounding Rock in Horizontal Layered Tunnels under High Crustal Stress Based on 3DEC Simulation[J] MODERN TUNNELLING TECHNOLOGY, 2022,V59(4): 127-136
2022, Vol. 59 