动、静载荷下不同角度裂缝对类砂岩力学特性影响试验研究

发布时间：2019-01-03 10:48

【摘要】：岩石作为一种复杂地质体,在其形成和变化的地质历史时期中,经受过各种复杂而不均衡的地质作用,其内部通常会含有节理、裂隙等不规则缺陷,随着岩土工程开挖、卸荷等扰动,岩石中的这些缺陷会进一步扩展、贯通,造成岩石破坏,近年来对含有节理、裂隙等缺陷岩石力学特性的研究已经成为了岩石力学界和工程界广泛关注的焦点,该课题已经成为热门的前沿课题之一。本文以鲁甸县砂岩为模拟对象,并对天然裂缝进行简化展开试验研究。首先从理论角度分析了裂缝对岩石力学特性的影响,然后在室内制备了类砂岩试件并对其进行试验,分别在静载和动载条件下对试验结果进行分析,通过对比研究获得以下结论：(1)动、静载荷下预制裂缝的角度均会改变试件的力学性质,不同程度地影响其内部裂隙的产生、扩展和贯通模式,进而降低试件的强度,同时裂缝发生不同程度的闭合。(2)动、静两种试验条件下,完整试件、0°裂缝试件与90°裂缝试件的破坏模式主要是裂纹贯通试件顶底部,而发生的劈裂张拉破坏,45°裂缝试件的破裂面与加载方向有一定的倾角,试件会同时发生剪切破坏和拉伸破坏。(3)动载下试件的破碎程度和极限强度均高于静载,是因为动载下试件应变率的提高,参与扩展的裂纹数量增加,两种试验条件下裂缝试件的强度均低于完整试件,当裂缝角度相同时,试件的破坏模式也相同。本文以含有不同角度的预制裂缝类砂岩试件为试验对象,对动、静荷载下裂纹的演化过程和试件的力学特性进行了分析,旨在探讨裂缝对岩石力学特性的影响规律,为相关岩土工程提供理论参考。
[Abstract]:As a kind of complex geological body, rock has experienced various complex and uneven geological processes in the geological history of its formation and change, and its interior usually contains irregular defects such as joints, fractures, etc., and with the excavation of geotechnical engineering, With disturbance such as unloading, these defects in rock will be further expanded and penetrated, resulting in rock failure. In recent years, the study of mechanical properties of rock containing joints and cracks has become the focus of attention in rock mechanics and engineering. This subject has become one of the hot frontier topics. In this paper, the sandstones in Ludian County are taken as simulation objects, and the natural fractures are simplified and studied experimentally. In this paper, the influence of fracture on rock mechanical properties is analyzed theoretically, then sandstone like specimen is prepared and tested in laboratory, and the test results are analyzed under static load and dynamic load, respectively. The conclusions are as follows: (1) the angle of precast cracks under dynamic and static loads will change the mechanical properties of the specimens, and affect to some extent the generation, expansion and penetrating mode of internal cracks, and then reduce the strength of the specimens. At the same time, the cracks are closed to different degrees. (2) under the dynamic and static test conditions, the failure mode of the intact specimen, the 0 掳crack specimen and the 90 掳crack specimen is mainly the crack through the top and the bottom of the specimen, and the splitting tensile failure occurs. The fracture plane of 45 掳fracture specimen has a certain inclination angle with the direction of loading, and the shear failure and tensile failure will occur simultaneously. (3) the breaking degree and ultimate strength of the specimen under dynamic load are higher than those of static load, because the strain rate of the specimen under dynamic load increases. The strength of crack specimen is lower than that of complete specimen under two kinds of test conditions, and the failure mode of specimen is the same when the crack angle is the same. Taking prefabricated fractured sandstone specimens with different angles as experimental objects, the evolution process of cracks and the mechanical properties of specimens under dynamic and static loads are analyzed in this paper. The purpose of this paper is to discuss the influence of cracks on the mechanical properties of rocks. To provide theoretical reference for related geotechnical engineering.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TD315

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