Assessing the range of blasting-induced cracks in the surrounding rock of deeply buried tunnels based on the unified strength theory  

基于统一强度理论的深埋隧道围岩爆破致裂范围评估

作　　者：LI Liang CHEN Jia-jun ZHAO Lian-heng HE Ke-pei HU Shi-hong LI Hua-long 李亮;陈嘉骏;赵炼恒;何可培;胡世红;李华隆(School of Civil Engineering,Central South University,Changsha 410075,China;Key Laboratory of Heavy-haul Railway Engineering Structure,Ministry of Education,Central South University,Changsha 410075,China;Hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structure,Central South University,Changsha 410075,China)

机构地区：[1]School of Civil Engineering,Central South University,Changsha 410075,China [2]Key Laboratory of Heavy-haul Railway Engineering Structure,Ministry of Education,Central South University,Changsha 410075,China [3]Hunan Provincial Key Laboratory for Disaster Prevention and Mitigation of Rail Transit Engineering Structure,Central South University,Changsha 410075,China

出　　处：《Journal of Central South University》2024年第7期2341-2364,共24页中南大学学报（英文版）

基　　金：Project(2021JJ10063)supported by the Natural Science Foundation of Hunan Province,China;Project(202115)supported by the Science and Technology Progress and Innovation Project of Hunan Provincial Department of Transportation,China;Project(2021K094-Z)supported by the Science and Technology Research and Development Program of China Railway Guangzhou Group Co.,Ltd。

摘　　要：Blasting-induced cracks in the rock surrounding deeply buried tunnels can result in water gushing and rock mass collapse,posing significant safety risks.However,previous theoretical studies on the range of blasting-induced cracks often ignore the impact of the in-situ stress,especially that of the intermediate principal stress.The particle displacement−crack radius relationship was established in this paper by utilizing the blasthole cavity expansion equation,and theoretical analytical formulas of the stress−displacement relationship and the crack radius were derived with unified strength theory to accurately assess the range of cracks in deep surrounding rock under a blasting load.Parameter analysis showed that the crushing zone size was positively correlated with in-situ stress,intermediate principal stress,and detonation pressure,whereas negatively correlated with Poisson ratio and decoupling coefficient.The dilatancy angle-crushing zone size relationship exhibited nonmonotonic behavior.The relationships in the crushing zone and the fracture zone exhibited opposite trends under the influence of only in-situ stress or intermediate principal stress.As the in-situ stress increased from 0 to 70 MPa,the rate of change in the crack range and the attenuation rate of the peak vibration velocity gradually slowed.深埋隧道围岩的爆破致裂可能导致地下涌水和岩体坍塌,存在重大安全隐患。然而,现有关于围岩爆破致裂范围的理论研究通常忽略了中主应力和地应力的影响。为准确评估深埋隧道围岩的爆破致裂范围,本文以炮孔空腔膨胀的两阶段Jones-Miller绝热方程为基础,建立了围岩位移与裂隙半径的动力控制方程;并基于统一强度理论推导了围岩应力、位移和裂隙半径的理论解析式。参数分析表明,在爆破荷载作用下,围岩的粉碎区范围与地应力、中主应力和孔壁压力呈正相关,与泊松比和不耦合系数呈负相关,随剪胀角取值的改变而呈现非单调特性。与粉碎区相比,破裂区范围分别在剪胀角、泊松比、孔壁压力和不耦合系数影响下的变化趋势一致,而在地应力或中主应力影响下呈现相反的变化趋势。随地应力从0增大至70 MPa,围岩爆破致裂范围的变化速率和围岩振速峰值的衰减速率逐渐减缓。本文研究成果可为深埋隧道钻爆工程实际中围岩裂隙范围的控制与安全评估提供理论指导。

关 键 词：deep drilling and blasting cracks in surrounding rock unified strength theory intermediate principle stress in-situ stress cavity expansion dilatancy characteristics 

分 类 号：U451.2[建筑科学—桥梁与隧道工程]