Influence of stone content on face stability for tunnels in sandy cobble strata

Frontiers in Earth Science

Earth Science

Yonghao Zhang¹  Jianbin Zhao¹  Lingyun Li²  Xiaoqin Gong²  Haifang Xue²  Ying Zhao³  Haoteng Wang⁴ 

[1] China National Logging Corporation, Xi’an, China;Qinghai Traffic Investment Co., Ltd., Xining, China;Qinghai Xihu Expressway Management Co., Ltd., Xining, China;School of Highway, Chang’an University, Xi’an, China;State Key Laboratory of Eco-Hydraulics in Northwest Arid Region, Xi’an University of Technology, Xi’an, China;

关键词: numerical simulation;    sandy cobble stratum;    stability of tunnel face;    stone content;    safety factor;   

DOI  :  10.3389/feart.2023.1200079

 received in 2023-04-04, accepted in 2023-05-31,  发布年份 2023

来源: Frontiers

【 摘 要 】

As a result of the complex geological conditions of sand-cobble stratum, various types of problems may arise during construction of tunnels crossing sand-cobble stratum, the most prominent of which is the stability problem of the face. In order to study the stability of the tunnel face in sand-cobble stratum, first, a continuous medium model of sandstone soil is established, and numerical simulation is carried out on the three-axis compression test of sandstone soil to analyze its micro-mechanical characteristics. Second, a calculation model of simulated sandstone strata excavation is established by FLAC3D finite difference software. Then, the safety factor K calculated by the strength reduction method is introduced as the evaluation index of the face stability, and the face stability of sand-cobble tunnels with a series of stone content, tunnel burial depth and tunnel diameter are analyzed. The results show that the macro stress-strain curve of sand-cobble soil in the three-axis compression test can be divided into linear stage, elastic-plastic stage and ideal plastic stage, and the shear strength of sand-cobble soil increases with the increase of stone content. In the process of tunnel excavation, the stability of tunnel face increases with the increase of stone content in the stratum; while the tunnel buried depth and diameter increase, the stability of tunnel face decreases. These results provide a reference for predicting the instability and failure of sand-cobble tunnels, which is critical for the construction and safety of tunnels in sand-cobble stratum.

【 授权许可】

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Copyright © 2023 Xue, Wang, Li, Gong, Zhao, Zhao and Zhang.