【作者】 汪亦显；

【导师】 曹平； K.XIA；

【作者基本信息】 中南大学 ， 土木工程， 2012， 博士

【摘要】 岩体中含有大量的初始缺陷,包括空隙、孔隙、微裂纹、节理等,初始缺陷的存在增加了水与岩体接触的程度,改变了岩体的力学和变形特性。工程实践表明水—岩作用是影响岩体工程稳定性的重要因素之一,水与岩体的相互作用效应,不仅包含渗透压力的作用效应,而且还存在着复杂的水—岩化学腐蚀作用,研究表明大部分岩体工程的失稳破坏均与水—岩作用密切相关。目前,随着大规模的岩体工程的建设和营运,为了保证其长期稳定性,针对岩体工程在水环境影响作用下的研究工作具有重要的理论参考价值和良好的工程应用价值,可为边坡工程、水利坝基、公路涵洞、桥梁隧道、地下采矿、石油开采等工程稳定问题研究提供科学依据。本文研究内容依托国家自然科学基金资助项目(50774093：水岩作用下裂隙岩体流变—损伤—断裂耦合理论及应用；51174228：考虑动水压作用和裂隙表面形貌影响的岩体裂隙开裂扩展研究)、湖南省研究生创新基金项目(CX2009B046：裂隙岩体水腐蚀损伤流变效应的非线性研究)以及中南大学优秀博士研究生学位论文扶植基金(2009ybfz06：裂隙岩体损伤流变断裂效应的非线性研究)。采用损伤断裂力学理论,从实验研究、理论分析和数值模拟等多方面研究水岩共同作用下裂隙岩体的损伤变形和断裂破坏机理进行了深入系统的研究。主要开展了以下几个方面的研究工作：(1)为研究水化腐蚀对岩石损伤作用,进行了岩体化学损伤效应的动力反应过程分析,研究了水岩接触后矿物成分溶解速率的计算,从理论上探讨了化学腐蚀下等效裂纹扩展的定量化分析方法,通过质量守恒定律计算出裂纹在迹长及隙宽方向的变化,将水化腐蚀后等效成有效裂纹长度,建立了水-岩化学作用下等效裂纹扩展的计算公式。(2)为研究水作用下软岩损伤劣化效应的时间相依性,采用RYL-600岩石试验机和Instron1342电液材料伺服试验机对经过水浸泡不同时间后的软岩试验样品进行力学参数以及双扭试件的亚临界裂纹扩展试验,分别得到了软岩含水率、强度与变形参数、亚临界裂纹扩展速度矿与应力强度因子KI、断裂韧度KI等参数。试验结果分析表明：软岩含水率、力学参数等与水岩作用时间具有高度线性相关性,可以通过含水率和弹性模量建立软岩劣化损伤速率6的函数关系；通过采用双对数坐标空间对常位移松弛法所测试的不同浸泡时间的软岩亚临界裂纹扩展速度V与应力强度因子KI之间的关系研究,发现lgKI-lgV关系具有极好的线性相关性,而且水腐蚀损伤对软岩断裂力学性质有弱化作用,能加快膨胀性软岩亚临界裂纹的扩展,并且软岩水腐蚀作用对岩石裂纹的断裂指标影响显著并具有时间效应。(3)为研究含初始损伤岩体渐进损伤断裂机制,通过采用预埋抽条法利用水泥砂浆为类岩材料制作不同几何空间分布的多裂纹体进行断裂破坏实验,对单轴加载下含初始损伤裂纹试样的预制裂纹扩展、贯通方式及强度损伤随裂隙空间展布和裂隙数量变化规律进行了探讨。(4)为研究渗透压作用下含初始损伤岩体的断裂演化,进行了渗透水压力对岩石的损伤断裂研究。对有充填物的压剪裂纹,将损伤概念引入裂纹模型,定义了新的损伤变量,推导出水损伤作用下压剪裂纹的应力强度因子；对处于压剪和拉剪应力状态的含单裂纹岩体,在水作用下的损伤起裂进行了探讨,给出了考虑水损伤的单裂纹断裂准则。(5)为研究在动态载荷作用下脆性岩石损伤断裂的演化过程,利用分离式霍普金森压杆(SHPB)装置中压缩气体发射球体子弹对脆性岩板进行变角度冲击损伤实验,岩板受到冲击后,边缘出现凹坑,表面裂纹从撞击凹坑扩展到岩板边缘,实验中样品的表面裂纹能有效表征其内部的开裂状况,能有效反映冲击能量的耗散。破裂区面积与裂纹表面积随入射能量呈非线性增长趋势,同时与入射角度相关,但当破裂区面积急剧下降时,裂纹表面积反而急剧上升,表明裂纹的发生发展有明显的孕育期,在入射能量达到临界值前,主要表现为裂纹孕育增长,在达到临界值后,发生宏观断裂破坏,裂纹面积呈负增长,破裂区面积增大。(6)为揭示岩体的爆破损伤及损伤累积效应,基于裂纹扩展和声速变化,探讨了岩体损伤及其累积情况的计算方法,针对含水裂隙岩体的爆破损伤问题,进行了水作为垫层和空气作为垫层时的损伤分析；对爆破损伤变量进行定义和推导推导。对数值损伤云图进行了分析,结果表明不同介质作为垫层时,在相同爆破能量下,其引起的损伤区不相同,含水岩体的损伤度要大于以空气作为垫层的岩体损伤。现场监测结果表明爆源距离决定了岩体损伤度,离爆源越近,损伤增量和累积损伤愈大,其变化情况呈非线性,随着爆源距离增加,累积损伤值的变化趋势趋缓,实际监测和计算模型的误差在工程容许的范围内,因而本文探讨的计算岩体爆破损伤方法可以为现场监测结果分析的提供比对依据。更多还原

【Abstract】 The rock mass contains a large number of initial defects, including holes, pores, microcracks, and joints, etc., the existence of initial defects increase the level of water-rock contact and change the mechanics and deformation characteristics of rock mass. The project practice indicates, water-rock interaction is one of the important factors to influence the stability of rock mass engineering, the effect of water-rock interaction does not only includes seepage pressure, but also exists the effect of complex water-rock chemical corrosion, research shows that most rock mass instability and faluire is closely related to water-rock interaction. Nowadays, with the development of large-scale construction project, the studies on mechanical characters of rock mass under the action of water have important theoretical significance and practical value to ensure the long-term stability of rock engineering, The results can provide scientific bases for engineering stability research, such as slope, dam, tunnel, underground mine, oil exploitation.This work has been supported by the National Natural Science Foundation of China (NO.10972238), Hunan Provincial Innovation Foundation for Postgraduate (No.CX2009B046), Hunan Safety Production Technology Development Guidance Project (2009) and the Graduate Degree Thesis Innovation Foundation of Central South University (No.2009ybfz06&No.1343-0024). The paper has carried out the research work involving several aspects as follows:(1) In order to research the corrosion behavior of hydration effect in rock damage, the dynamical reaction process of rock chemical damage effect has been analyzed. The calculation of dissolution rate of mineral components after the contact of water and rock has been studied. And in theory, it has been discussed the quantification analytical method of equivalent crack propagation under the chemical corrosion. By adopting the Law of conservation of mass, it has been worked out the variables in the directions of crack length and width and the hydration corrosion has been equivalent to the effective crack length. Finally it has been established the calculated formula of effective crack length under the chemical water-rock interaction and the stress intensity factor has been worked out.(2)In order to study the time-dependent of damage and degradation effect for soft rock under water corrosion, subcritical crack growth of soft rock was studied by double torsion test using Instron1342type electro hydraulic servo test machine and the mechanics parameters test using RYL-600rock test machine after marinated soft rock in water for different time. Based on testing results, the rate of water content (ω), the mechanics parameters, the subcritical crack growth velocity (V) and the stress intensity factor (KI) and the fracture toughness (KIc) were obtained respectively, the results show that the rate of water content(ω) VS the time of water-rock interaction relations accord with good linear rule and could established the function relationship of damage and degradation velocity(D) for soft rock by means of the rate of water content(ω) and elasticity modulus(E); And the results analysis for the relationship of subcritical crack growth velocity(V)and stress intensity factor(KI) of soft rock in different time were studied by double logarithm coordinate, the results show that lgKrlgV relations accord with good linear rule and the fracture mechanics effect of water corrosion action of swelling soft rock is evident and time-dependent, and the water corrosion damage can accelerate subcritical crack growth velocity(V) and can weaken fracture mechanical characteristic of swelling soft rock.(3) In order to study the gradual damage fracture mechanism of initial damage rock mass, the macro-mechanical experiments on regular cracks body in initial damage rock-like materials have been made. Using white cement as the similar materials, the rock-like specimens in which the cracks were arranged in different echelon design through pre-installed steel slice were produced, the research on the models of fracture propagation and coalescence, as well as the law of strength variation with the cracks collocation and crack numbers under uniaxial loading were summarized systematically. (4) For studying the fracture evolution of rock mass that contained initial damage under the osmotic pressure, the influence of seepage pressure to rock fracture and damage has been investigated. For those frictional cracks with filler, it has been deduced the stress intensity factor of crack under the osmotic pressure with leading the damage concept into the crack model and new definition of damage variable. For the rocks that have single crack under both the compression-shear and tensile-sheared stresses, their initiation damage has been discussed under water condition. Finally, the fraction criterion of single crack rock has been given with consideration about water damage.(5) In order to study the evolutionary process of brittle rock damage and fracture under impact loading, the dynamic damage was studied by variable angle impact test using compressed gas of SHPB to launch the ball to impact the lateral margin of rock plate, when a source of impact loading is applied to a rock plate specimen, damage cracks are developed from the source to the boundaries, and the surface cracks are able to effectively represent sample internal cracking condition and can effectively reflect the impact energy dissipation in these tests. Test results show that the cracks propagation length and break area are not arbitrary, but are influenced by the angle of dynamic impact loading. The crack length and the break area increase with the increase of the impact loading, when the break area decreases abruptly, the crack length increases suddenly, it shows that there was an obvious incubation period of crack forming, at first some pits appeared on the verge of the rock plate and the propagation rate of crack length and break area decreases with increasing the impact velocity.(6)In order to reveal blast-induced damage cumulative effect of rock mass, based on crack expansion and sonic speed variation, the calculation method about the rock mass damage and its cumulation has been discussed to discover the explosion damage and the damage accumulation on effect. The numerical damage cloud chart has been analyzed. The result shows that the same explosion energy can cause different damage areas with different cushion, and the damage of water-saturated rock mass is bigger than that of air cushion rock mass. Field monitoring result has been indicated that the source distance determines the rock damage degree:with the distance getting closer, the damage increment and accumulation are getting more. The error between numerical model and field monitoring is in the engineering permissible range. Thus, the calculation method of rock explosion damage in the paper can offer the compared basis for field monitoring. This research puts forward a new calculation method for measuring the damage of rock mass. So, this new calculation method can be used as a comparison basis for site monitoring of blast-induced damage of rock mass.更多还原