【作者】 孙博；

【导师】 张社荣；

【作者基本信息】 天津大学 ， 水工结构工程， 2012， 博士

【摘要】 高埋深地下洞室结构的大量兴建是人类未来生存与发展的必然需求，其围岩破坏机理及其稳定性是现阶段国内外岩土工程界研究的重点和难点问题之一。依托西部某深埋输水隧洞，基于颗粒离散元法、室内物理试验原理、离心模型试验理论及超载理论，由深埋粉砂岩的力学行为入手，本文从六大方面、宏细观相结合的角度详细分析了高埋深地下洞室围岩破坏机理及其稳定性，初步得到了以下成果：（1）深埋硬岩的力学行为。深埋粉砂岩的力学行为受加载方式、围压和卸载速率的影响，且微裂纹大量萌生时刻均位于峰后且靠近峰值强度，其分布及数量与加载方式、围压及卸载速率有关，是试样破坏模式不同的本质原因。（2）含孔洞硬岩破裂机理研究。含孔洞粉砂岩试样的破坏规律与完整试样基本相同，只是更易受加载方式和围压的影响。中主应力大小和方向均对含孔洞粉砂岩试样的力学行为具有较大的影响，其破坏特征（脆性或延性）由最小主应力及中主应力与最小主应力之差决定；同时其破坏模式不仅与中主应力的大小有关，还与其方向有关，其根本原因在于孔洞对试样的削弱作用与围压对变形抑制作用的相互影响。（3）不同断面形式下洞室结构破坏机理研究。“先加载、后开洞”与“先开洞、后加载”获得的洞室破坏模式及其发展过程是有差别的。断面形式和侧压力系数均影响洞室开挖后的应力重分布，引起岩体细观微裂纹的萌生、扩展与分布差异较大，进而造成岩体宏观破坏模式不同；一定范围内的侧压力系数对洞室稳定是有利的，但断面形式不同，侧压力系数的临界值不同。（4）深埋地下洞室结构岩爆破坏机理研究。不论是卸载岩爆还是加载岩爆，岩爆发生时应力变化规律和能量变化规律基本相同。但是岩爆方式不同、最小围压不同，岩爆的具体破坏机理是不同的，并且最小围压对两种岩爆方式的影响是有差别的。（5）开挖过程中深埋地下洞室围岩稳定性研究。侧压力系数不同，开挖过程中洞室失稳破坏机理不同，可能发生的岩爆形式不同，AE事件时空分布不同。总体来看，深部岩体在开挖扰动影响下，首先在洞壁表面和开挖面附近区域形成破坏损伤区，而后随着开挖面的不断推进，开挖损伤区逐渐向深部发展，其具体发展形态与其侧压力系数关系极大。（6）节理对深埋地下洞室稳定性的影响。基于颗粒离散元法编写直剪试验数值程序，应用该程序建立节理细观参数与其宏观力学特性的关系。根据真实岩体中节理分布的统计规律，编写生成随机断续节理的子程序，并将其嵌入颗粒离散元法。节理连通率不同，开挖过程中洞室围岩失稳破坏的具体形态、微裂纹分布及其综合位移分布等是有一定差别的；整体来看，随着节理连通率的增加，洞室围岩失稳破坏的可能性增大。更多还原

【Abstract】 Widespread construction of deep buried underground caverns is the inevitabledemand of human survival and development in the future. At present, the failuremechanism and stability of surrounding rock is one of the key and difficult problemsof the geotechnical engineering at home and abroad. Relied on one deep buriedunderground cavern in the Western China and based on particle flow theory, physicalexperimental principles, centrifugal model theory and overload method, this paperanalyzes the failure mechanism and stability of deep buried surrounding rock ofunderground cavern from six aspects and macro-micro point of view. The results ofthis study are listed as follows.（1）Mechanical behavior of the deep-buried hard rock. The mechanicalbehavior of siltstone is influenced by loading method, confining pressure andunloading rate. The time of microcracks forming largely is post and close to peakstrength, and its distribution and number is related to loading method, confiningpressure and unloading rate, which is the essential reason of different failure modes.（2）Failure mechanism of the hard rock with a pre-existing hole. The failurerule of siltstone with a pre-existing hole is basically the same as that of wholespecimen, but is influenced more easily by loading method and confining pressure.The size and direction of intermediate principal stress have a significant effect onmechanical behavior of siltstone, and its failure feature (brittleness or ductility) isdeterminated by minimum principal stress and the difference of intermediate andminimum principal stresses. Meanwhile, its failure modes of siltstone specimen aredetermined by the amplitudes and directions of intermediate principal stress, and arerelated to weakening effect of the opening and inhibition effect of confining pressurein essence.（3）Failure mechanism of underground caverns with different sections. Thefailure modes and failure processes are different between "loading before excavation"and "loading after excavation". Sections and lateral pressure coefficients have animpact on stress redistribution after excavation, which leads to the differences of theformation, propagation and distribution of microcracks. Lateral pressure coefficient within limits is benefit for the stability of underground caverns. But the critical valuesof lateral pressure coefficients are different with different sections.（4）Rockburst’s failure mechanism of deep buried underground cavern. Nomatter whether loading or unloading tests of rock burst, the change rules of stress andenergy during the process of rock burst is fundamentally the same. However, thespecific failure mechanism of rock burst is different when test modes and/or minimumconfining pressure are different. And the influence of minimum confining pressure onunloading or loading tests of rock burst is discriminatory.（5）Stability study of deep buried surrounding rock of underground cavernduring the excavation process. When lateral pressure coefficients are different, failuremechanism of underground cavern, possible rock burst’s types and the spatial andtemporal distribution of AE are different. On the whole, damage zone firstly forms onthe surface of tunnel wall and excavation face by excavation disturbance,subsequently develops toward the deep areas with the advance of excavation face.And its development is related to lateral pressure coefficient.（6）Influence of joints on the stability of deep buried underground cavern.Based on particle flow code, numerical program of direct shear test is compiled andapplied to relate the microparamaters of joints and its macromechanics features.According to the statistical law of joints’ distribution in real rocks, subroutine ofrandom intermittent joints is compiled and embedded in particle flow code. Whenconnectivity rates of joints are different, specific failure modes of surrounding rockduring the excavation process, the distribution of microcracks and comprehensivedisplacements are different. On the whole, the buckling failure possibility ofsurrounding rock increases with the increase of connectivity rates.更多还原