双裂隙细砂岩蠕变破裂演化特征与锚杆加固止裂效应试验研究

发布时间：2018-03-31 12:43

本文选题：细砂岩　切入点：预制裂隙　出处：《华北水利水电大学》2017年硕士论文

【摘要】：本文利用RLJW-2000微机控制岩石三轴剪切流变仪和PCI-II声发射系统,对不同预制裂隙长度的细砂岩试样以及不同数量锚杆锚固的裂隙试样进行了单轴压缩蠕变声发射试验,研究双裂隙细砂岩蠕变破裂时的裂纹扩展过程以及锚杆对裂隙试样的加固止裂效应,研究结果表明:(1)以完整试样作为标准,预制裂隙长度为20mm和30mm时,蠕变破坏时的强度分别降低了37.66%和65.71%。预制裂隙长度对试样的强度影响显著。(2)双裂隙岩石试样的破坏都表现为拉剪贯通模式,新的裂纹首先从两条预制裂隙的内部尖端开始起裂,随着应力的增加,微裂隙主要沿着预制裂隙方向向试样上下端部扩展、连接与贯通,最终导致试样的破坏。预制裂隙长度对裂隙破坏模式的影响:预制裂隙越长,试样最终破坏的主裂隙形式越简单,且破裂面较为平直;预制裂隙越短,试样最终破坏的主裂隙形式越复杂,破坏越充分,且裂隙多呈弧形形式。这与声发射事件点的空间演化特征吻合。(3)以未加锚的试样作为标准,水平单锚试样和水平双锚试样蠕变破坏时的强度分别提高了7.79%和22.14%。锚杆对裂隙试样的加固作用明显,双锚加固的作用大于单锚加固的作用。(4)与未加锚的试样相比,加锚试样的声发射事件点延伸到锚杆所在位置时,事件数均明显减少;加锚试样的宏观裂隙向内扩展到锚杆位置时,形成了楔形破裂面,次生裂隙和破裂断面多呈弧形形式,锚杆对微裂纹的扩展起到了抑制作用,同时改变了裂隙的扩展方向,且双锚的抑制作用优于单锚。
[Abstract]:In this paper, RLJW-2000 microcomputer controlled triaxial shear rheometer of rock and PCI-II acoustic emission system are used to carry out uniaxial compression creep acoustic emission tests for fine sandstone specimens with different prefabricated fracture lengths and fracture specimens with different numbers of anchors.The process of crack propagation during creep fracture of double fractured fine sandstone and the effect of anchoring bar on strengthening crack specimen are studied. The results show that the crack length is 20mm and 30mm when the complete specimen is taken as the standard and the length of prefabricated crack is 20mm and 30mm.The strength of creep failure decreased by 37.66% and 65.71% respectively.Prefabricated fracture length has a significant effect on the strength of the specimen. (2) the failure of the rock specimens with double fissures shows a tension-shear through mode. The new crack starts from the inner tip of the two prefabricated fractures and begins to crack with the increase of stress.The microfracture mainly extends to the upper and lower end of the specimen along the direction of the precast fracture, which leads to the failure of the specimen.The influence of prefabricated fracture length on fracture failure mode: the longer the prefabricated fracture, the simpler the main fracture form of final failure of the specimen, and the more straight the fracture surface, the shorter the prefabricated fracture, the more complex the main fracture form of the final failure of the specimen.The more sufficient the damage, and the fracture more arc form.This is consistent with the spatial evolution characteristics of AE event points. The strength of horizontal single anchor specimens and horizontal double anchor specimens under creep failure is increased by 7.79% and 22.14%, respectively, using unanchored specimens as the standard.The reinforcement effect of anchor rod on fracture specimen is obvious, the effect of double anchor reinforcement is greater than that of single anchor reinforcement. Compared with unanchored specimen, the number of events of anchor specimen when the AE event point extends to the position of anchor rod is obviously reduced.When the macroscopic crack of anchored specimen extends inward to the position of anchor rod, the wedge fracture surface is formed, and the secondary crack and fracture section take the form of arc. The anchor rod can restrain the propagation of microcrack, and change the direction of crack propagation at the same time.The inhibitory effect of double anchor is better than that of single anchor.
【学位授予单位】：华北水利水电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU45

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