三维应力下花岗岩剪切变形破坏特征试验研究

发布时间：2018-02-15 13:02

本文关键词： 双面剪切单面剪切声发射表面形貌　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：岩石是一种由多种矿物质组成的非均质体,所以岩石的性质比较复杂。在自然界以及工程中,岩石的受力状态十分复杂,所以研究岩石的破坏规律具有一定的困难。岩体失稳破坏的主要形式之一是剪切破坏,包括单面剪切和双面剪切。岩石在不同应力状态下的破裂规律具有很大的差别,所以研究岩石在不同应力状态下的破裂特征有重大意义。鉴于以上分析,本文进行了不同应力条件下花岗岩的单面剪切和双面剪切破坏特性的试验研究,比较不同应力状态下剪应力-位移曲线中各个阶段的特点,同时结合声发射技术,进一步探讨岩石破坏过程中各个阶段的声发射特征,并借助3D激光扫描仪扫描剪切面的表面形貌,以更好的把握岩石破裂规律。通过研究发现:(1)花岗岩单面剪切和低法向应力的双面剪切破裂全过程中,剪应力-位移曲线大致可以分成4个阶段:加载调整段(OA)、弹性变形段(AB)、弹塑性变形段(BD)、峰后变形段(DE)。但是双面剪切过程中,当法向应力大于50MPa时,例如70MPa时,花岗岩破裂过程的剪应力-位移曲线多出了一段很长的塑性变形强化段,表现出了很强的塑性。(2)花岗岩单面剪切破坏过程中,随着法向应力的增加,岩样的峰值抗剪强度、残余抗剪强度、弹性变形段斜率以及峰值强度与残余强度之比都逐渐增加,花岗岩的单面剪切摩擦系数逐渐减小。(3)花岗岩双面剪切破坏过程中,随着法向应力的增加,岩样的峰值抗剪强度和残余抗剪强度逐渐增加,弹性变形段斜率和峰值强度与残余强度之比逐渐减小,双面剪切摩擦系数先增大再减小。(4)在花岗岩单面剪切过程中,随着法向应力的增加,当剪应力达到花岗岩的峰值抗剪强度时,声发射计数和能量先增大后减小,声发射计数累计和能量累计逐渐减小。(5)在花岗岩双面剪切过程中,随着法向应力的增加,当剪应力达到花岗岩的峰值抗剪强度时,声发射计数、能量和能量累计逐渐增大,声发射计数累计先减小后增大。(6)花岗岩单面剪切和双面剪切破坏后,随着法向应力的增加,(?)的值逐渐减小。说明法向应力越大,剪切面凹凸不平度越小。
[Abstract]:Rock is a heterogeneous body composed of a variety of minerals, so the properties of rock are complex. In nature and engineering, the stress state of rock is very complicated. Therefore, it is difficult to study the failure law of rock mass. One of the main forms of rock failure is shear failure, including one-sided shear and two-sided shear. The fracture law of rock under different stress states is very different. Therefore, it is of great significance to study the fracture characteristics of rocks under different stress states. In view of the above analysis, this paper has carried out an experimental study on the single and double shear failure characteristics of granite under different stress conditions. The characteristics of each stage in the shear stress-displacement curve under different stress states are compared. At the same time, combined with acoustic emission technology, the acoustic emission characteristics of each stage in the rock failure process are further discussed. With the help of 3D laser scanner, the surface morphology of the shear plane is scanned to better understand the rule of rock fracture. It is found that during the whole process of one-sided shear and low-normal stress two-sided shear fracture of the granite, The shear stress-displacement curve can be roughly divided into four stages: load adjustment section, elastic deformation section, elastic deformation section, elastic-plastic deformation section, and post-peak deformation section, but in the double-sided shear process, when the normal stress is greater than 50 MPA, for example, 70 MPA, In the shear stress-displacement curve of granite fracture process, there is a long plastic deformation strengthening section, which shows a very strong plastic deformation strengthening section.) in the process of single face shear failure of granite, the peak shear strength of rock sample increases with the increase of normal stress. The residual shear strength, the slope of elastic deformation section and the ratio of peak strength to residual strength increase gradually, and the friction coefficient of one-sided shear of granite decreases gradually. The peak shear strength and residual shear strength of rock samples increase gradually, and the slope and the ratio of peak strength to residual strength of elastic deformation section decrease gradually. With the increase of normal stress, when shear stress reaches the peak shear strength of granite, the AE count and energy increase first and then decrease. With the increase of normal stress, when shear stress reaches the peak shear strength of granite, the acoustic emission count, energy and energy accumulative increase gradually. With the increase of normal stress? It shows that the greater the normal stress, the smaller the roughness of the shear plane.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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