高温后花岗岩物理力学性质试验研究
发布时间：2018-01-18 10:12
本文关键词：高温后花岗岩物理力学性质试验研究 出处：《中国地质大学(北京)》2017年硕士论文 论文类型：学位论文
【摘要】：高温岩体地热开发利用、高放核废料地下深层处置等高温岩石力学问题涉及到高温对岩石的作用。在高温作用下,岩石的物理性质、力学性质、化学成分都会发生剧烈变化,因此高温对岩石物理力学性质的影响规律近年来成为专家学者们的研究热点。花岗岩作为高温岩石力学中广泛遇到的岩石类型,其在高温作用下物理力学性质的变化规律受到研究人员的关注。本文以经过不同高温处理后的花岗岩岩样为研究对象,观察了高温前后花岗岩岩样外观变化以及矿物形态变化,量测了高温前后花岗岩岩样物理性质(质量、体积、密度、纵波波速)变化,得到了高温对花岗岩物理性质的影响规律。除此之外,我们对不同高温处理后的花岗岩岩样进行了单轴与三轴实验,得到了高温对花岗岩力学性质(抗压强度、峰值应变、弹性模量、粘聚力、内摩擦角)的影响规律。主要结论如下:(1)500℃及以下温度对花岗岩物理力学性质影响较小,600℃开始,温度对花岗岩影响较大,因此600℃为高温影响花岗岩物理力学性质的阈值;(2)花岗岩物理性质指标变化规律主要是:随着温度的升高,花岗岩暗色矿物氧化程度越来越高,岩样红棕色逐渐加深、质量降低、体积增大,密度减小,纵波波速降低;(3)600℃时光镜下观察到矿物表面产生裂纹,并出现蚀变重结晶现象,800℃时裂纹变宽并发生贯通,1000℃时矿物发生熔融重结晶,裂纹减少,矿物表面变模糊;800℃时花岗岩岩样表面出现可见裂纹,1000℃时可见裂纹增多;(4)随着温度的升高,花岗岩应力应变曲线压密阶段变长,弹性变形阶段变短,屈服阶段逐渐变长,花岗岩表现出软化特性;(5)单轴条件下,随着温度上升,花岗岩强度降低,弹性模量降低、峰值应变增长;三轴条件下,随着温度上升,花岗岩强度变化较小,弹性模量降低,峰值应变增长;(6)随着温度升高,花岗岩粘聚力降低,内摩擦角有稍微上升的趋势;(7)500℃以下温度处理后的花岗岩岩样破坏形式均为剪切破坏,600℃以上温度处理过的岩样在围压低于15MPa时表现为拉伸破坏,高于15MPa时,转变为剪切破坏,因此15MPa为花岗岩破坏形式转变围压。
[Abstract]:The problems of high temperature rock mechanics, such as geothermal exploitation and utilization of high temperature rock mass and deep underground disposal of high radioactive nuclear waste, are related to the effect of high temperature on rock. Under the action of high temperature, the physical properties and mechanical properties of rock are concerned. Chemical composition will change dramatically, so the influence of high temperature on the physical and mechanical properties of rock has become a hot spot of experts and scholars in recent years. Granite is a widely encountered rock type in high temperature rock mechanics. The change of physical and mechanical properties under high temperature has attracted the attention of researchers. In this paper, granite samples after different high temperature treatment are taken as the research object. The physical properties (mass, volume, density, longitudinal wave velocity) of granite samples before and after high temperature were observed. In addition, we have done uniaxial and triaxial experiments on granite samples after different high temperature treatment, and obtained the mechanical properties (compressive strength) of granite treated by high temperature. The effects of peak strain, elastic modulus, cohesion force and angle of internal friction). The main conclusions are as follows: the temperature below 1 鈩，
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