软弱围岩隧道开挖应力扰动特征试验及数值模拟  

Model Experiment and Numerical Simulation of Characteristics of Stress Disturbance Induced by Tunnel Excavation in a Soft Rock Mass

作　　者：徐前卫[1] 程盼盼[1] 朱合华[2] 丁文其[2] 陈国中 

机构地区：[1]同济大学道路与交通工程交通部重点试验室,上海201804 [2]同济大学岩土与地下工程交通教育部重点试验室,上海200092 [3]中铁七局集团第二工程有限公司,西安710032

出　　处：《现代隧道技术》2016年第6期154-164,共11页Modern Tunnelling Technology

基　　金：国家自然科学基金重点项目(41130751);西部交通建设科技项目(2011ZB04)

摘　　要：文章结合武宁—吉安高速公路隧道工程,以Ⅳ级围岩为对象,采取模型试验和数值模拟相结合的方法,分别对拱顶上方有、无断层两种情况下隧道开挖引起的围岩塌方破坏的渐进性过程以及岩体内部的应力演化规律开展研究,从而为隧道塌方事故的预防和支护结构设计提供借鉴和参考。研究结果表明:(1)隧道开挖后,拱腰以下岩体往往因应力集中程度较高而率先剪切破坏;(2)当有断层存在时,隧道开挖使得断层下盘岩体处于悬挑状态而容易出现拉剪破坏;(3)隧道开挖主要对自两侧拱脚向上与水平面成45°+φ/2范围内的岩体有影响,而塌落破坏的岩体只占此影响区域的一小部分;(4)断层的存在使得拱顶上方岩体径向压力在隧道开挖后更易于出现降低,且应力降低范围相对无断层时的要大;(5)当无断层存在时,拱顶上方岩体切向应力集中是伴随着岩体的开裂和塌落而逐步由隧道周边向外侧发展的,而当有断层存在时,拱顶上方切向应力集中则出现在距拱顶更远的位置。Based on the Wuning-Ji＇an highway tunnel projects, and taking soft and fractured rock masses as a re- search object, model experiments and numerical simulations were conducted to study the progressive failure mecha- nism and the stress development sequence of surrounding rock, with and without faults, above the tunnel crown, pro- viding a reference for the prevention of collapse and the design of lining structures. Research results show that： 1） shear failure of the rock mass often occurs below the tunnel haunch after tunnel excavation due to highly concentrat- ed stress; 2） in a tunnel with faults, the rock mass below the fault can be placed in a cantilevered state and is prone to tension and shear failure; 3） the influence zone caused by tunnel excavation is mainly located between two in- clined planes starting from the arch springline with an angle of 45°＋φ/2 to the horizontal plane--the collapsed rock mass only accounts for a small part of this affected area; 4） due to the existence of the fault, the radial stress in the rock mass above the tunnel crown is reduced after excavation, and the scope of such stress reduction is larger than if there is no fault; and 5） the tangential stress concentration of the rock mass above the tunnel crown gradually devel- ops from the tunnel perimeter towards the outside, accompanied by rock cracking and collapse when there is no fault; the concentration of tangential stress occurs at a farther position from the crown when there is a fault.

关 键 词：隧道 软弱破碎围岩 渐进性破坏 模型试验 数值模拟 

分 类 号：U451.5[建筑科学—桥梁与隧道工程]