Study on Deformation Mechanism and Support Measures of Soft Surrounding Rock in Muzhailing Deep Tunnel

Abstract

The deformation of Muzhailing deep tunnel is about 2.3 m in the process of construction, which is difficult to be controlled by the traditional “anchor-grouting integration” support system. This paper deeply analyzes the geological characteristics, rock mechanics characteristics, and surrounding rock failure characteristics of Muzhailing tunnel. The deformation mechanism and the failure of the support system are analyzed through the numerical simulation, theoretical analysis, and field test. The authors propose support measures suitable for Muzhailing tunnel based on the analysis results. The maximum buried depth is 600 m, and the engineering rock mass at the depth has nonlinear physical and mechanical phenomenon. The maximum principal stress of Muzhailing tunnel is 25.7 MPa, which belongs to high-stress joint swelling soft rock tunnel. The NPR cable can achieve large deformation under the condition of constant support resistance. The authors put forward the coupling support mode of “NPR cable + steel arch frame + concrete,” which is based on the idea of transforming the composite deformation mechanism to a single type. The stress concentration appears in the range of 12 m in the surrounding rock circle, and the lateral and vertical stress distributions are relatively symmetrical after the improved support. The circumferential strain of the surrounding rock is greatly reduced, and the range of strain is reduced by 10%. The field monitoring results show that the new support system can well control the large soft rock deformation of Muzhailing tunnel (0.5 m). The support strategy proposed can effectively control the large deformation and promote the formation of new support concept for deep tunnel.

Study on the Deformation Mechanism of a Soft Rock Tunnel

“…Aksoy et al [14] adopted a non-deformable support scheme for the large deformation tunnel. Tao et al [15] found that the deformation of the Muzhailing tunnel was due to the plastic flow and swelling deformation of the surrounding rocks. In a case study, Wang et al [16] studied and optimized the construction scheme and supporting technology for the high stress and jointed soft rock tunnel.…”

Deformation Mechanism and Support Technology of Deep and High‐Stress Soft Rock Roadway

“…At present, the main mining countries have entered into the deep mining stage and initiated for developing deep roadway support which normally faces challenges in deep mining [1,2]. It is difficult to ensure the stability of the deep broken soft rock roadway due to several influencing factors such as mining activities, rock mass physical and mechanical properties, and high-stress field, which directly cause difficulties in finding the stability control of surrounding rock [3][4][5][6][7][8][9][10][11]. e abundant scientific research achievements have been done by many researchers around the world to solve the ground support problem of deep soft surrounding rock roadway through developing new technology for deep soft rock roadway surrounding rock control, new theory, and performing the industrial test.…”

Analysis of Stress and Deformation Characteristics of Deep‐Buried Phyllite Tunnel Structure under Different Cross‐Section Forms and Initial Support Parameters

“…ey compared the numerical simulation with the field test data and concluded that the NPR anchor support significantly reduced the asymmetric deformation of the tunnel surrounding rock, and the deformation of the surrounding rock was smaller than that of the steel arch support. Tao et al [28] proposed an improved "NPR cable + steel arch frame + concrete" support mode. Yang et al [29] proposed a support scheme for deep-buried soft rock roadways, namely, a new "bolt-cable-mesh-shotcrete + shell" combined support.…”