石英砂岩力学特性及各向异性试验研究

发布时间：2018-10-12 08:41

【摘要】：为研究不同应力条件下层理对高孔隙率岩石材料破坏模式、弹性模量以及强度的影响,针对各向异性的石英砂岩,采用静水预压缩增大轴向应力的加载方式,进行了多组带有不同层理角度试样的三轴试验。试验结果表明,不同应力条件下各向异性的石英砂岩试样表现出不同的变形破坏特征,以30 MPa围压为界,低围压范围内破坏模式为剪切型破坏,在该范围内随着围压增大破坏面由倾斜转向水平,并受到试样层理角度不同程度的影响,高围压范围内受到层理的影响分为剪切屈服和体积屈服两种破坏模式;随着围压的增大,新闭合的孔隙裂纹数目减少,各向异性对弹性模量的影响呈现降低趋势,弹性模量增长速率降低,弹性模量在层理分布角度?=60°时都会出现下降的现象;不同层理分布试样的强度曲线呈U型,围压在0~20 MPa范围内试样?=30°强度最低,围压在30~60 MPa范围内强度最低试样转化到?=45°附近;不同层理角度石英砂岩的强度特征系数随着围压的增大而逐渐减小,围压大于30 MPa后该系数逐渐趋于稳定。
[Abstract]:In order to study the effects of bedding on the failure mode, elastic modulus and strength of high porosity rock materials under different stress conditions, a static water precompression method is used to increase axial stress for anisotropic quartz sandstone. Triaxial tests with different bedding angles were carried out. The experimental results show that the anisotropic quartz sandstone specimens exhibit different deformation and failure characteristics under different stress conditions, and the failure mode is shear type in the range of low confining pressure with 30 MPa confining pressure as the boundary. In this range, the failure surface changes from inclined to horizontal with the increase of confining pressure, and is affected by different degrees of stratification angle of specimen. In the range of high confining pressure, the failure modes of shear yield and volume yield are divided into two kinds of failure modes: shear yield and volume yield. With the increase of confining pressure, the number of newly closed pore cracks decreases, the effect of anisotropy on elastic modulus decreases, the growth rate of elastic modulus decreases, and the elastic modulus decreases when the bedding distribution angle is 60 掳. The strength curve of the specimens with different bedding distribution is U shape, the strength of the specimens is the lowest in the range of 0 ~ 20 MPa, and the lowest is? = 45 掳in the range of 30 ~ 60 MPa. The strength characteristic coefficient of quartz sandstone with different bedding angles decreases with the increase of confining pressure, and the coefficient tends to be stable when the confining pressure is more than 30 MPa.
【作者单位】：北京科技大学金属矿山高效开采与安全教育部重点实验室;大连理工大学工程力学系;
【基金】：国家自然科学基金项目(No.51574014)~~
【分类号】：TU45

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