【作者】 叶洲元；

【导师】 李夕兵；

【作者基本信息】 中南大学 ， 工程力学， 2008， 博士

【摘要】 在世界范围内浅部资源正日益枯竭,深部资源开采迫在眉睫。然而,随着深井采矿、核废料储存、石油开采、地质钻探等人类活动的不断深入地下,地应力呈非线性增加,地温升高,并发现深部岩石有着许多现有岩石力学知识无法很好解释的现象,如:深井岩爆、岩石的脆延转化,破坏特征异常、岩体分区破裂化现象等。为什么会出现这些问题呢?事实上,深部地下资源的开发过程中,矿岩在受到诸如爆破震动等动载荷作用前,就已经处于很高的静应力场或地应力场中。由于浅部岩体埋深小,所受到的地应力较小,岩体的稳定性问题利用目前现有的岩石力学知识就可较好的解决。而类似于上述提到的深部岩体问题利用浅部的办法来解决,效果不理想,因此在动力扰动下高应力岩石的力学行为是目前岩石力学界和采矿工程界研究的难点和重点。针对上述问题,本文作者在国家自然科学基金重大项目资助下,以动静组合加载下岩石破坏特性的研究为主要内容,就一维和三维动静组合加载理论与实验进行了深入系统的研究。论文作者利用改进的霍布金逊压杆冲击试验装置对砂岩进行了一维和三维动静组合加载试验,研究了砂岩在不同水平轴向静压和不同水平围压下受应力波扰动作用时的力学响应和破坏特征。在机理研究方面,利用内部含有圆盘片状裂纹的圆柱体模型,计算其受到不同形式的外力作用时的应力场,通过数值模拟再现裂纹的扩展过程,从而分析高应力岩石在动载作用下的断裂破坏机理,并利用不同的力学元件,组合建立了受动静组合载荷下岩石的力学本构模型,并在此基础上,分析了岩石在不同静载下的应变能密度的变化规律。在本构理论方面,阐述了岩石是由许多自相似结构的力学元件组合的微结构构成的集合体,利用力学元件的性质,将不同性质的力学元件组合起来,建立了一维和多维受静载荷作用的岩石在动载作用下的本构模型。在强度理论方面,用应变能密度定义了岩石在动静组合载荷作用下的破坏准则,根据能量守恒规律推导出动静组合加载下岩石破坏过程中应变能密度。在动静组合加载本构模型的基础上,导出模型受力过程中的应变能密度,求出了受一维或三维静载岩石在动载作用下破坏的应变能密度的临界值。在工程应用方面,将动静组合载荷下岩石受力条件和岩石发生岩爆的条件及两者发生的现象进行了对比,认为室内动静组合加载试验可以模拟再现现场发生的岩爆,并通过分析动静组合载荷下岩石破坏过程中能量的转化来揭示岩石发生岩爆的能量要求,而且发现了动静组合加载能量利用的规律,找到提高能量利用率的措施和利用深部岩体受力状况来致裂岩石的手段。本文所做的研究工作,立足于学科前沿,运用各种理论和实验方法,对动静组合加载下的岩石力学与破坏特性及工程实践中的动静组合加载的力学问题进行了研究,具有较高的理论和应用价值,为系统开展深部岩体力学特性的研究奠定了理论和实验基础。更多还原

【Abstract】 It is necessary to mine deep resources for the shallow resources are increasingly exhausted in the world. However, as the underground human activities (deep mining, nuclear waste storing, oil extracting and geology drilling etc.) stepping deeper, the in-situ stress increases nonlinearly, the ground temperature rises higher, and there also have lots of other phenomena such as rock burst in deep shaft, rock brittle-ductile transition, abnormal failure characteristics, zonal disintegration and so on, which are not well explained by the existing rock mechanics. Why do the questions occur? In fact, during the exploitation of resources in deep, rock is already in the condition of high static stress or ground stress before they are subjected to dynamic stress such as blasting vibration. Rock stability can be well solved by existing rock mechanics due to small buried depth and low ground stress in shallow rock mass, but it is not the case for rock in deep. Therefore, the researches of rock mechanics and mining engineering at present emphasized on mechanical behavior of high statically loaded rock under dynamic loads. For these questions above, systemic theoretical and experimental researches of rock mechanical behavior under static-dynamic coupling loads in one and three dimension are carried out in this paper with the support of the National Natural Science Foundation of China.The improved SHPB testing system which can load static axial pressure and confining pressure is employed to carry out static-dynamic coupling loading test. The mechanical response and failure characteristics of sandstone loaded by stress wave under different axial and confining pressure are studied. In the research of mechanism, the stress fields are calculated under different loads and the crack growth process is simulated through numerical software based on the cylinder model with a penney crack in. Thus, the fracture and failure mechanism of high stress rock is analyzed under dynamic loads, a new mechanical constitutive model under static-dynamic coupling loads is established with different machine elements, and the rule of strain energy density is researched.On the aspect of constitutive relationship, rock is made up of many microstructures constituted by self-similar machine elements, and a constitutive model of rock under uniaxial or triaxial static loading plus dynamic loading is established by way of combining microstructures with different mechanical properties.On the aspect of strength theory, strain energy density is used to define a failure/fragmentation criterion of the rock under static-dynamic coupling loading. According to Conservation of Energy, a formula calculating strain energy density is obtained. The strain energy density during rock failure is deduced based on the constitutive model of rock under coupled static-dynamic loads, and the critical value of rock strain energy density under static-dynamic coupling loading is derived.In engineering application, we think that the rock laboratory experiments may simulate and reshow rock bursts considering the conditions of coupled static-dynamic loads and rock burst and their comparison. Energy demand of rock burst occurring is revealed through analyzing energy transition of rock failure process under coupled static-dynamic loads. At the same time, the rule of energy utilization under coupled static-dynamic loads is discovered; the measures for rock cracking by utilizing high stress condition in deep rock mass and energy utilization improving are found.The characteristics of rock failure under coupled static-dynamic loads and the problem in engineering are researched in this dissertation based on the subject frontier, various theoretical and experimental methods. The results of this dissertation are useful both theoretically and practically, and established the foundation for systemically researching the mechanical characteristics of rock mass in deep.更多还原