循环荷载下裂隙岩体能量演化及损伤特性试验研究

发布时间：2018-06-26 10:42

本文选题：裂隙岩体 + 裂纹贯通模式　；参考：《成都理工大学》2015年硕士论文

【摘要】：自然岩体是一种非连续介质体,其内部充斥着大量裂隙、空隙等缺陷,使岩体力学性质呈现明显的各向异性。节理、裂隙在外载下的扩展、贯通对岩体的力学特性产生显著的影响,也是导致岩体发生局部化破坏的主要原因。因此,对裂隙岩体力学性质和变形破坏化过程的正确分析具有十分重要的工程意义。从能量观点可知,岩体的破坏本质上是能量耗散和释放的结果,从能量角度研究岩体变形破坏的力学相应特点及本质特征,能较真实的反映岩体的破坏规律。本文通过相似材料模拟玄武岩等脆性材料,制作不同裂隙倾角及长度的单裂隙试样和不同空间分布的双裂隙试样。以PIV粒子高速成像测速技术方法作为试验观测手段,采用自主研发“YY-L600型”双轴压缩试验系统进行双轴循环压缩试验。分析了裂隙试样的力学性质、变形破坏过程及裂纹贯通模式。从能量观点,研究了在加载过程中裂隙试样的能量演化规律、能耗特征及损伤特性。主要成果如下:(1)预制裂隙对试件的力学及强度特性影响明显,同等加载条件下,完整试样的峰值强度明显高于含裂隙试样的峰值强度。起始循环值、围压及裂隙的组合形式对试样的轴向应力-应变曲线的整体形态影响较小,但是会影响试样的峰值强度、起裂强度/峰值强度的比值;(2)预制单裂隙和双裂隙试件破坏过程大致经历四个阶段:初始压密阶段,弹性变形阶段,次生裂纹萌生和扩展,预制裂隙四周次生裂纹加速扩展,试件整体失稳破坏。双裂隙试件与单裂隙试件比较,起裂的时间早,大规模的裂纹贯通时间较单裂隙试件早,峰值强度低于单裂隙试件;(3)单裂隙裂纹和双裂隙裂纹在扩展过程中都产生翼裂纹,准共面次生裂纹及倾斜次生裂纹,但单裂隙裂纹在预制裂隙中间产生竖直的倾斜次生裂纹,这是双裂隙试件所不具有的,双裂隙裂纹在上下预制裂隙中间岩桥区域剪切裂纹的形式贯通,并没有以竖向张拉裂纹贯通,这主要原因是裂隙间间距较小,应力集中效应使得岩桥没有形成竖向张拉裂纹;(4)依据断裂力学裂纹的不同形式和裂隙扩展破坏过程,可以将单双裂隙试样在双轴循环加载条件下裂纹扩展模式分为张性贯通、张剪复合贯通和剪性贯通三大类,根据最终贯通裂纹类型不同,每个大类又可细分为若干亚类。对应于裂纹扩展贯通模式,可将试样的破坏模式分为三类,既张拉破坏模型、剪切破坏模型及张剪复合破坏模型;(5)单裂隙试件和双裂隙试件,在循环加载过程,能量演化都呈现非线性增长趋势,能量在变形破坏过程的各阶段呈现不同的转化形式。试件能量耗散特性的影响因素主要有裂隙长度、裂隙倾角、岩桥长度、裂隙组合方式及加载围压五个方面;(6)不同几何尺寸及组合的裂隙试件,其极限储能不同。在同一围压条件下,试样的极限储能起始循环值的相关性不明显,而裂隙倾角及裂隙长度对试样的极限储能有较大的影响。试样的极限储能与其抗压强度具有较好的相关性,抗压强度越高,试件在破坏前储存的可释放应变能越大,既随着抗压强度的增大,试件的极限储能储能越大;(7)试件不同变形阶段对应不同的能量演化规律。从破坏形式上来看,试件破坏形态与峰后能量集中释放程度有较好的对应性。从破坏形态上来看,峰前耗散能量越多,岩石内部扩展发育的裂纹越多,试件破坏后岩块越小,破碎度越高,既裂隙试件破碎程度:张剪复合破坏试件最大,剪切破坏试件次之,张拉破坏试件最小;(8)单裂隙试件和双裂隙试件其损伤变量与轴向应力曲线都呈非线性关系,且各个试件都具有相似的曲线形式,随着应力的不断增大,试件的损伤变量不断增大。损伤变量D与轴向之间的关系可以表达为:。
[Abstract]:Natural rock mass is a discontinuous medium, which is filled with a large number of cracks and gaps, which makes the mechanical properties of rock mass apparent anisotropy. Joints and cracks are extended under the external load. Penetration has a significant influence on the mechanical properties of rock mass, which is also the main cause of rock mass destruction. The correct analysis of the mechanical properties of body and the process of deformation and destruction is of great engineering significance. From the point of view of energy, the destruction of rock mass is the result of energy dissipation and release. The mechanical characteristics and essential characteristics of rock mass deformation and failure are studied from the angle of energy. It can reflect the failure law of rock mass more truly. The similar material simulated the brittle materials such as basalt, and made the single fracture specimens with different fracture angles and lengths and the double fracture specimens with different spatial distribution. The double axis cyclic compression test was carried out by the self developed "YY-L600" biaxial compression test system by the PIV particle high-speed imaging velocity measurement technique. The mechanical properties of the fractured specimen, the deformation and failure process and the crack penetration mode. From the energy point of view, the energy evolution law, the energy consumption characteristics and the damage characteristics during the loading process are studied. The main results are as follows: (1) the prefabricated fissure has an obvious effect on the mechanical and strength characteristics of the specimen, and the peak strength of the complete specimen under the same loading condition. The initial cycle value, the confining pressure and the combination of cracks have little influence on the overall shape of the axial stress strain curve of the specimen, but it will affect the peak strength of the specimen, the ratio of the cracking strength / peak strength, and (2) the failure process of the prefabricated single and double fracture specimens is roughly four orders. Section: initial compaction stage, elastic deformation stage, secondary crack initiation and expansion, accelerated propagation of secondary cracks around prefabricated cracks, overall instability and failure of specimens. Compared with single fracture specimens, double fissure specimen and single crack specimen are earlier than single fissure specimens, and peak strength is lower than single fissure test; (3) single fissure cracking. Cracks of wings, quasi coplanar secondary cracks and inclined secondary cracks occur during the propagation process, but single crack cracks produce vertical inclined secondary cracks in the middle of the prefabricated fissures, which are not found in the double fracture specimens. The double crack cracks are connected in the form of the shear crack in the middle rock bridge area in the upper and lower precast cracks. The main reason is that the vertical tensile crack is through, the main reason is that the gap between cracks is small, the stress concentration effect makes the rock bridge not forming the vertical tensile crack. (4) according to the different forms of fracture mechanics and crack propagation, the crack propagation mode can be divided into tensioning through the double axis cyclic loading condition. There are three major categories of shear combined penetration and shear penetration. According to the types of final through through cracks, each large class can be subdivided into several subclasses. Corresponding to the mode of crack propagation through, the failure modes of the specimen can be divided into three categories: tensile failure model, shear failure model and Zhang Jianfu's combined failure model; (5) single fracture specimen and double fracture specimen, In the cyclic loading process, the energy evolution shows a nonlinear growth trend, and the energy is different in various stages of the deformation and failure process. The influence factors of the energy dissipation characteristics are five aspects: fracture length, fracture angle, rock bridge length, fracture combination and loading confining pressure; (6) different geometrical sizes and combinations The limit storage energy is different. Under the same confining pressure, the correlation of the initial cycle value of the ultimate energy storage of the specimen is not obvious, and the fracture angle and the length of the crack have great influence on the limit energy storage of the specimen. The ultimate energy storage of the specimen has a good correlation with the compressive strength, the higher the compressive strength, the storage of the specimen before the damage. The greater the release strain energy is, the higher the compressive strength is, the greater the energy storage energy of the specimen is, and (7) the different deformation stages of the specimen correspond to the different energy evolution laws. From the form of failure, the damage form and the concentration of energy concentration after the peak are better. The more cracks developed in the rock, the smaller the rock mass, the smaller the rock mass, the higher the fracture degree, the fracture degree of the fracture specimen, the maximum of the fracture specimen, the shear failure test, the minimum tensile failure test, and (8) the nonlinear relationship between the damage variable and the axial stress curve of the single fracture and the double fracture specimens. All the specimens have similar curvilinear form. As the stress increases, the damage variable of the specimen increases continuously. The relationship between the damage variable D and the axial direction can be expressed as:.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU45

【参考文献】