【作者】 张哲；

【导师】 唐春安；

【作者基本信息】 东北大学 ， 工程力学， 2007， 博士

【摘要】 目前,公路、铁路隧道工程建设以及采矿工程中巷道工程设计、施工、稳定性评价及其支护措施等都直接依赖于对围岩岩体的强度、变形、岩体损伤与破裂规律等特征的研究。开挖扰动区岩体的研究是一个前沿热点研究课题,但目前尚无成熟的系统研究方法。本文在对开挖扰动区(EDZ)国内外研究现状进行了较为全面回顾的基础上,对开挖扰动区的相关理论进行了系统分类和归纳,对隧道开挖扰动后围岩的破坏模式及稳定性判据进行了全面分析,总结了以往研究方法及有关模型的优缺点,提出了开挖扰动区研究的本质和特点。从岩石材料的细观结构入手,利用细观力学的研究方法,抓住岩石材料及其力学性质的非均匀性,借助于统计学和现有的数值计算方法,以理论分析和实验结果及现场实测数据为基础,结合隧道开挖、采矿工程巷道施工维护工程实例,建立数值模型,进行围岩开挖扰动区的变形、破坏过程的数值分析,研究了扰动区的形成过程、机理及扰动范围。本文从开挖载荷诱发岩石损伤与破裂过程入手,在建立卸荷作用下围岩拉应力区、剪应力区损伤本构关系基础上,研究了不同断面隧道开挖扰动诱发的应力积累和应力迁移等规律,重点对连续岩体、含节理岩体、层状岩体中隧道开挖卸荷的扰动区形成过程和机理进行了研究,阐述了隧道围岩中弱结构体的存在使围岩变形和松动区形态发生奇异变化的影响规律。针对不同的岩体类型,具体分析了开挖后岩体的位移场、应力场变化,并阐释了从弹性区到塑性区以至发生破裂产生残余变形过程的力学演化规律。同时考查了巷道开挖卸荷围岩的蠕变效应,及在动态应力波作用下巷道的失稳破坏过程。本文的研究成果将充实岩体力学等相关学科的基础理论,提高开挖扰动区(EDZ)研究的水平和应用范围,为隧(巷)道设计施工、地质灾害预测预报提供重要参考价值,具有一定的理论价值和实践意义。更多还原

【Abstract】 In the design and construction of underground laneway, we not only concern the size and direction of ground stresses before the laneway is excavated, but also more pay attention to the state of the stress redistribution of the surrounding rock induced by excavation. In the stress analysis of the surrounding rock of the laneway, theoretical analysis may give the stress distribution at the surrounding rock in circular or elliptical roadway. Finite element method has extensive flexibility, may consider some complex laneway with arbitrary shape, and gives the stress distribution at the surrounding rock. Knowledge of the stress distribution as well as the deformation and failure process of roadway pays an important role in controlling the roadway stability and selecting appropriate support parameters.Theoretical analysis for the rock stress surrounding the roadway of circular or elliptical roadway subjected to different ratios between pressures in horizontal and vertical directions is carried out by using elastic theory. The equation of tangential stress around the roadway boundary is given, and stress distribution around boundary of the circular and elliptical roadway is summarized. The figures of tangential stress distribution around the boundary of elliptical roadway with different lateral pressure coefficient are drawn. According to finite element atlas of underground engineering analysis, the stress distribution of surrounding rock of the arch laneway is calculated. The figures of stress distribution at the surrounding rock of laneway are drawn. The distribution rules of tensile stresses and compressive stresses around the roadway boundary are summarized. When a tunnel or an underground structure is excavated in rock mass, rock disturbed or damaged zone (EDZ) is formed around the tunnel due to the stress concentration resulting from stress redistribution. Recent studies on the rock EDZ revealed its important to structural stability around underground opening. In this study, the fracture and damage mechanisms of rock induced by the accumulation of microcracks were investigated by AE tests.The results of the experiments showed that tensile failure was the major microscopic failure mechanism of rock in excavation damaged and distrubed zone. The damage of tunnel surrounding rock masses usually results from the redistribution of stress indisturbed rock mass in tunnel excavation process. The excavation-disturbed zone (EDZ) is defined as the rock zone where the rock properties and conditions, such as fracture, stress and hydraulic aperture, have been changed dueto the processes induced by excavation.EDZ is considered to be physically less stable and can form a continuousand highly permeable pathway of groundwater flow. The characterization of EDZ will affect tunnel supportstructure design, tunnel construction and tunnel surrounding rock mass stability analysis. Seismic surveytechniques can be, used to examine the nature of EDZ around the tunnel.Based on the concept of EDZ and theprimary factors that lead to the change of rock properties, a methodology is proposed to depict mechanical andhydraulic behavior of EDZ. By using the in-situ data, deformability and hydraulic properties are studied bynumerical analysis. The results show that the excavation damage depends on the excavation method. In addition, the influence boundary of the excavation-disturbed stress zone is smaller than that of the seepage. Therefore, theseepage boundary condition should be emphasized in establishing the coupled fluid-solid numerical models. Theresults will make the establishment of coupled fluid-solid model more reasonable.更多还原