含水砂岩围压条件下的力学性能试验研究

发布时间：2018-07-06 08:45

本文选题：岩石力学 + 含水砂岩　；参考：《河南理工大学》2014年硕士论文

【摘要】：地下工程岩体处于复杂的地质力学环境中,其力学性质受地下水、地应力及外界载荷等因素影响较大。针对以往试验因素单一的不足,本文进行了考虑含水率、应变速率和围压等因素共同作用下砂岩力学性能的试验研究。本文以常见的红砂岩为研究对象,首先参照含水率岩样制备的基本方法,进行真空抽气快速制备含水率岩石试样方法的试验研究,并进行了试验验证。然后通过真空抽气法快速制备含水砂岩岩样,在RMT301岩石与混凝土力学试验系统上进行了含水砂岩中低应变率下的单轴和三轴压缩试验,确定三因素对岩石力学参数的影响规律,并分析三因素之间的相互影响关系。最后进行含水率和应变率下,基于不同分布的砂岩分段损伤本构模型比较研究。以求对地下工程支护结构设计和围岩的长期稳定提供理论支持。通过试验研究得出,不同岩石采用真空抽气法和自然浸水法得到的含水率与试验时间都呈对数关系。三因素对砂岩力学性质的影响表现为,含水弱化效应、应变率强化效应和围压硬化效应。单轴压缩时砂岩的强度、峰值应变、弹性模量及变形模量与含水率、应变率有较好的拟合关系,三轴压缩时围压与砂岩力学参数亦有较好拟合关系,但在围压条件下,含水率及应变率与砂岩力学参数的关系变得复杂。三因素之间存在一定的相互影响关系,整体来说,围压的增大,减小了含水弱化效应和应变率强化效应;含水率的增大,加强了围压硬化效应,单轴压缩时减小了应变率强化效应;应变速率的增大,削弱了围压硬化效应,单轴压缩时增大了含水弱化效应。砂岩的破坏形式受围压影响较大,和含水率没有明显关系,但随着应变速率的增加,更容易出现剪切破坏形式。单轴压缩下,考虑压密段的分段式损伤本构模型优于传统一段式损伤本构模型,基于幂函数分布的损伤本构模型优于基于Weibull分布的损伤本构模型。
[Abstract]:Underground engineering rock mass is in a complex geological and mechanical environment, its mechanical properties are greatly affected by underground water, ground stress and external load and so on. In view of the lack of single test factors in the past, the mechanical properties of sandstone under the combined action of moisture content, strain rate and confining pressure were studied. In this paper, the common red sandstone is taken as the research object. Firstly, with reference to the basic method of water cut rock sample preparation, the method of rapid preparation of water cut rock sample by vacuum extraction is studied, and the test results are verified. Then the water-bearing sandstone rock samples were prepared quickly by vacuum extraction method. Uniaxial and triaxial compression tests of water-bearing sandstone at low strain rate were carried out on RMT301 rock and concrete mechanical test system, and the influence of three factors on rock mechanics parameters was determined. The interaction between the three factors is analyzed. Finally, the constitutive models of sandstone segmental damage based on different distributions under water content and strain rate are compared and studied. In order to provide theoretical support for underground engineering supporting structure design and long-term stability of surrounding rock. The experimental results show that the water content obtained by vacuum extraction method and natural immersion method is logarithmic with the test time. The effects of three factors on the mechanical properties of sandstone are water weakening effect, strain rate strengthening effect and confining pressure hardening effect. Under uniaxial compression, the strength, peak strain, elastic modulus and deformation modulus of sandstone have a good fitting relationship with moisture content and strain rate, and the confining pressure also has a good fitting relationship with the mechanical parameters of sandstone under triaxial compression, but under confining pressure conditions, The relationship between water content and strain rate and the mechanical parameters of sandstone becomes complicated. As a whole, the increase of confining pressure reduces the weakening effect of water cut and strain rate strengthening effect, and the increase of water content strengthens the confining pressure hardening effect. Under uniaxial compression, the strain rate strengthening effect is reduced, the confining pressure hardening effect is weakened with the increase of strain rate, and the water content weakening effect is increased during uniaxial compression. The failure form of sandstone is greatly affected by confining pressure and has no obvious relationship with water content. However, with the increase of strain rate, shear failure is more likely to occur. Under uniaxial compression, the segmented damage constitutive model is superior to the traditional one-segment damage constitutive model, and the damage constitutive model based on power function distribution is better than that based on Weibull distribution.
【学位授予单位】：河南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU45

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