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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。
In order to study the effect of bedding on failure mode, elastic modulus and strength of high porosity rock material under different stress conditions, anisotropic quartz sandstone was hydrostressed with hydrostatic pre-compression and axial loading. Triaxial test with specimens of different bedding angles. The experimental results show that the anisotropic quartz sandstone specimens under different stress conditions show different deformation characteristics. With the confining pressure of 30 MPa as the boundary and the failure mode as the shear type failure under the low confining pressure range, With the confining pressure increasing, the destructive surface changes from tilting to horizontal and is affected by the different degree of sample bedding angle. Under the influence of bedding in high confining pressure, there are two types of failure modes, shear yielding and volume yielding. The pressure increases, the number of newly closed pores decreases, the anisotropy has a decreasing trend on the elastic modulus, the elastic modulus increasing rate decreases, and the elastic modulus decreases at the layer distribution angle = 60 ° The intensity curves of samples with different bedding distributions are U-shaped. When the confining pressure is in the range of 0 ~ 20 MPa, the strength of the sample with the lowest value of 30 ° is the lowest, 45 °. The intensity characteristic coefficients of quartz sandstone with different bedding angles decrease with the increase of confining pressure. When the confining pressure is greater than 30 MPa, the coefficient gradually becomes stable.