基于数字图像技术对软、硬岩石中多裂纹起裂、扩展和连接机理的研究

发布时间：2018-03-27 22:21

本文选题：相似模型试验　切入点：多裂纹试样　出处：《重庆大学》2016年硕士论文

【摘要】：应用相似模型试验手段研究多裂隙岩体,并运用相关研究成果解决当前的一些岩土工程问题在现阶段具有实际的工程意义和指导作用。本文首先根据物理力学相似理论和前人有关相似试验的研究结果,找到能够模拟软、硬岩的延、脆性相似材料,浇筑试样并预制裂纹,再对其进行单轴加载试验,运用数字图像技术采集试验中试样破坏的图像信息,利用在试验过程中获得的各个试样的图像数据、荷载数据、位移数据,对裂纹的起裂、扩展和试样的贯通、破坏情况进行分析,取得的研究成果如下:(1)在岩石相似材料研究的基础上,采用砂作为粗骨料和重晶石作为细骨料,酒精作为有机溶剂,分别用“环氧树脂和聚酰胺”(简称“环-聚”)作为胶凝材料模拟软岩进行延性材料多裂纹相似模型试验,以及用“松香”作为胶凝材料模拟硬岩进行脆性材料多裂纹相似模型试验。(2)通过改变原材料的配比发现:原材料(“环-聚”或“松香”)含量的变化对试样的力学性质影响较大。随着“环-聚”或松香的配比不断增加,试样的起裂应力及峰值应力也不断增大,连接应力也不断增大。(3)通过改变裂纹的分布发现:裂纹的几何分布对试样裂纹的连接模式有着直接的影响。裂纹起裂以翼型裂纹为主,连接模式主要为翼型裂纹与次生共面裂纹的搭接将预制裂纹连接起来。(4)对比延性和脆性试样结果可知:从破坏模式的上看,延性组(环-聚组)试件破坏基本上是以拉剪复合破坏模式为主,而脆性组(松香组)试件的破坏模式包括拉剪复合型和张拉型破坏模式;从力学特性上看,延性组试样的起裂应力和峰值应力在一个较小的范围内波动,而脆性组的这个波动范围较延性组更大一些;对比延性组试样,脆性组试件破坏时产生的裂纹更多,尤其在试样表面产生了更多的微裂纹。(5)本文采用DIC数字散斑动态应变测量分析系统对裂纹起裂、扩展和连接过程进行了动态和实时捕捉,并分析了含裂纹试件破坏过程的位移场和应变场,结合试样的应力应变曲线,发现试件破坏过程中的位移和应变变化趋势与曲线基本一致,应变场和位移场图与宏观表面裂纹起裂、连接和试件的贯通、破坏过程高度一致,验证了该测量方法能够建立起细观力学与宏观力学的联系。
[Abstract]:The similar model test method is used to study the multi-fractured rock mass. And the application of relevant research results to solve some current geotechnical engineering problems has practical engineering significance and guidance at the present stage. Firstly, according to the theory of physical and mechanical similarity and the research results of previous similar tests, It is found that it can simulate the ductility and brittleness of soft and hard rock, cast the specimen and preform the crack, then carry out uniaxial loading test on it, and use digital image technology to collect the image information of the specimen damage in the test. Using the image data, load data and displacement data of each specimen obtained during the test, the crack initiation, propagation and failure of the specimen are analyzed. The results are as follows: (1) based on the study of similar rock materials, sand is used as coarse aggregate and barite as fine aggregate, alcohol as organic solvent. Using "epoxy resin and polyamide" (referred to as "cyclization") as cementitious materials to simulate soft rock, the similar model tests of ductile materials with multiple cracks were carried out. And using "rosin" as the cementing material to simulate hard rock for the similar model test of brittle materials with multiple cracks. (2) by changing the ratio of raw materials, it is found that the mechanical properties of the samples are affected by the change of the content of raw materials ("ring polymerization" or "rosin"). With the increasing of the ratio of "ring polymerization" or rosin, The crack initiation stress and peak stress are also increasing, and the joint stress is also increasing. 3) by changing the crack distribution, it is found that the geometric distribution of the crack has a direct effect on the crack joining mode of the specimen, and the crack initiation is mainly caused by the airfoil crack. The connection mode is mainly the overlap of the airfoil crack and the secondary coplanar crack to connect the precast crack with the precast crack. The results of ductility and brittleness show that: from the view of the failure mode, The failure mode of ductile group (ring-cluster group) is basically tension-shear composite failure mode, while the failure mode of brittle group (rosin group) is composed of tension-shear composite failure mode and tension-tensile failure mode. The crack initiation stress and peak stress of ductile group fluctuate in a small range, while that of brittle group is larger than that of ductile group. Especially, more micro-cracks are produced on the surface of the specimen.) in this paper, the crack initiation, propagation and bonding process are captured dynamically and in real time by using the DIC digital speckle dynamic strain measurement and analysis system. The displacement field and strain field of cracked specimen are analyzed. Combined with the stress-strain curve of the specimen, it is found that the variation trend of displacement and strain in the failure process of the specimen is basically the same as that of the curve. The strain field and displacement field diagram are highly consistent with the macroscopic surface crack initiation, connection and fracture process. It is verified that the measurement method can establish the relationship between micromechanics and macroscopic mechanics.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU45

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