不同卸荷速率下北山花岗岩力学特性试验研究

发布时间：2019-06-24 11:23

【摘要】：为探讨在增轴压卸围压的应力路径下不同卸荷速率对甘肃北山花岗岩力学性质的影响,对北山花岗岩进行了不同速率、不同围压条件下的卸荷试验,并与循环加卸载试验强度方面的数据对比分析,研究花岗岩的强度变形特征和破坏特点。研究结果表明:1围压效应明显,峰值强度随实时围压升高而增强;卸荷试验峰值强度包络线在循环加、卸载试验峰值强度包络线上方,且随着卸荷试验速率的升高,岩样峰值承载能力增强。2随着卸荷速率的增加,黏聚力增大,但内摩擦角变化较小且无明显规律;相比循环加卸载试验,卸荷试验的黏聚力降低了8%~20%,内摩擦角提高了9%左右。3随着围压的增加,卸荷试验峰值点至峰后应力跌落点的横向应变增量先减小后增加;不同围压下的卸荷起点至卸荷峰值点的横向应变增量在0.5~2.0 MPa/min卸荷速率区间内有相同的增减趋势。4随着卸荷试验速率的增加,岩样破裂面贯通程度增加;随着围压的升高,主破裂面破裂角增大,且破裂面更加平直。
[Abstract]:In order to study the effect of different unloading rates on the mechanical properties of the granite in the northern part of Gansu under the stress path of axial compression and pressure relief, the unloading test at different rates and different confining pressure conditions of the Beishan granite is carried out, and the data in the strength of the cyclic loading and unloading test are compared and analyzed. The characteristics and characteristics of the strength and deformation of the granite are studied. The results show that:1, the confining pressure effect is obvious, the peak intensity is enhanced with the increase of the real-time confining pressure, the peak intensity envelope of the unloading test is above the envelope of the peak intensity of the unloading test, and with the increase of the unloading test rate, the bearing capacity of the rock sample is enhanced. With the increase of the unloading rate, the cohesion is increased, but the internal friction angle is small and there is no obvious rule. Compared with the cyclic loading and unloading test, the cohesion of the unloading test is reduced by 8-20%, and the internal friction angle is increased by about 9%. With the increase of the confining pressure, the lateral strain increment of the unloading test peak point to the post-peak stress drop point is firstly reduced, the lateral strain increment of the unloading starting point to the unloading peak point under the different confining pressure is in the range of 0.5 to 2.0 MPa/ min, The penetrating degree of the rock-like rupture surface is increased; with the increase of the confining pressure, the fracture angle of the main rupture surface is increased, and the fracture surface is more straight.
【作者单位】：北京科技大学土木与资源工程学院;中核集团高放废物地质处置重点实验室;四川大学水利水电学院;
【基金】：国家自然科学基金项目(编号:51308196)
【分类号】：TU45

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