【作者】 刘亚群；

【导师】 李海波；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2009， 博士

【摘要】 动荷载(地震荷载或爆破荷载)作用下层状结构岩质边坡的变形破坏机理与安全研究是我国西部强地震区大型水利水电工程建设以及面临着大规模边坡爆破开挖的山区高速公路工程、水利水电工程以及核电工程建设中需要解决的难点和热点问题。本文主要针对层状岩体边坡(顺层和反倾岩体边坡),采用三维离散单元法(3DEC)对其在地震或爆破荷载作用下的变形破坏机理及稳定性分析进行了深入研究。本文首先针对含单一不连续面的理想顺层岩质边坡,采用三维离散元法研究了地震荷载作用下边坡的速度/加速度、应力、位移等动态响应特征、坡面的放大效应及其影响因素以及地震波在节理面的传播、衰减规律,并在此基础上深入分析了地震荷载作用下层状岩体边坡的变形和破坏失稳机理。针对含单一不连续面的理想顺层岩质边坡,采用三维离散元方法开展了地震荷载作用下边坡的稳定性研究。借鉴块体极限平衡分析思想,并考虑了地震动荷载的全时程特征,利用3DEC中FISH语言编程求出了潜在滑体的受力并将其沿潜在滑面分解求得潜在滑体的下滑力和抗滑力,从而求出了地震荷载作用下边坡的动安全系数历时曲线。结合数值模拟结果,通过综合分析整个地震荷载加载历时中边坡坡体关键点尤其是坡顶和潜在滑面附近质点速度矢量和位移矢量的的变化规律,定义了边坡的稳定状态、极限平衡状态和破坏状态,提出了边坡的收敛判断准则;在此基础上采用强度折减法确定了边坡的安全系数。并探讨了边坡在地震荷载作用下的基于极限平衡思想求得的动安全系数历时曲线与基于强度折减法求得的定值安全系数的对应关系。采用3DEC对依托工程溪落渡水电站左岸拱肩槽顺层岩体边坡在开挖卸荷和地震作用下的变形及稳定性进行了综合分析。分析结果表明:坡体在开挖卸荷过程中能保持稳定,并采用强度折减法计算了开挖后边坡的安全系数;在无支护条件下,在对应地震烈度8级、峰值加速度为0.18g的水平地震荷载作用下,边坡会失稳破坏;支护完成后,在峰值加速度为0.32g的地震荷载作用下边坡不会失稳破坏。此外,本文依托广东台山核电工程一期场平边坡爆破开挖工程,开展了爆破荷载作用下反倾层状岩质边坡的变形和破坏机理研究。提出了通过分析爆破荷载作用下边坡塑性区贯通与否并辅于边坡关键点位移收敛与否来确定反倾岩体边坡临界状态的方法,并结合强度折减法确定了爆破荷载作用下台山反倾岩体边坡的安全系数。更多还原

【Abstract】 Study on the deformation and failure mechanism and safety of layered rock slopes under dynamic loads, including seismic loads and explosions, is a difficult but also a hot problem in construction of hydraulic engineering in intensive earthquake areas of West China, and in construction of expressway and nuclear power engineering using drill and blast for foundation excavations. In this paper, the deformation characteristics and failure mechanism and stability of layered slopes under dynamic loads have been conducted in detail using three dimensional distinct element method (3DEC).At first, the dynamic response of an idea layered rock slope with a single discontinuity, including charatersitcs of velocity, and stress as well as displacement et. al., and amplitude effect of the slope subjected to seismic loads are conducted using 3DEC. Also the propagation and attenuation of seismic waves through the joints are analyzed. In addition, the deformation and failure mechanism of layered rock slopes under seismic loads are studied.The stability of the idea slope subjected to seismic loads is conducted using 3DEC. The force of potential sliding body is determined using the FISH program of 3DEC based on Limited Equilibrium Method. And the sliding force and resistance force of potential sliding body are obtained by the resolution of acquired body force along the potential sliding plane. Thus the varied factor of safety of the slope under seismic loads is obtained. In addition, the precise definition of stable status, limit balance status and failure status of the slope is formulated and the criterion of convergence judgment is proposed based on analyzing velocity and displacement vectors of critical points of slopes under the duration of seismic loads. And the factor of safety of the slope is determined based on the method of strength reduction. In addition, the result obtained by the method of combination of limited equlibirum method and 3DEC is compared with that by the method of strength reduction.The deformation and stability of the spandrel groove slope in Xiluodu hydropower station under both the excavation condition and seismic load are studied. It is suggested that the slope is stable under excavation condition and the factor of safety of the slope is computed using the strength reduction technique. It is also revealed that the slope losses its stability under the seismic load with the horizontal peak acceleration of 0.18g after the excavation of the slope without any supports. And the slope is stable under seismic load with the horizontal peak acceleration of 0.32g when support measurements finished.The deformation and failure mechanism of counter-tilt slope of Guangdong Taishan nuclear power station under explosions is studied. And a method to determine the limit balance status of the slope under explosions based on the plasticity zones transfixion of the slope is proposed. And the factor of safety of the slope is computed using the strength reduction technique and proposed method.更多还原