摘要
在岩石直剪试验过程中,上下剪切盒(夹具)之间往往需预留一定宽度的缝隙,但预留缝隙的宽度值没有明确的规定。采用相同直径、不同高度的大理岩试样进行直剪试验,研究上下剪切盒预留缝宽度对岩石抗剪强度和破坏特征的影响。试验结果表明:同一法向应力下,随着试验预留缝宽度的增加,试样剪切断裂面的正视图由一条近似直线逐渐变成三段近似直线构成的折线,剪切断裂面由水平曲面逐渐变为倾斜曲面,主导试样破坏的应力由剪应力逐渐变为拉应力;在同一法向应力下,试验预留缝宽度越大,测得的峰值抗剪强度值越小;随着预留缝宽度的增加,直剪试验获得的试样黏聚力整体上呈增加趋势,但变化不大,较为平稳,而内摩擦角则逐渐减小,且变化明显,幅度较大。试验预留缝宽度的取值对试验获得的抗剪强度、黏聚力、内摩擦角均存在影响,因此目前情况下在岩石直剪试验中应尽量减小预留缝宽度,而预留缝宽度的定量取值尚需进一步研究。
In the process of rock direct shear test, a gap with a certain width is usually reserved between upper and lower shear boxes(clamps), but the width value of the reserved gap is not clearly specified. Therefore, marble samples with the same diameter and different heights were used for direct shear tests, and the influence of the width of the reserved gap of the upper and lower shear boxes on the shear strength and failure characteristics of the rock was studied. Results show that under the same normal stress, with the increase of the width of the test reserved gap, the front view of the shear fracture surface of the sample gradually changed from an approximate straight line to a broken line formed by three approximate straight lines, and the shear fracture surface gradually changed from a horizontal curved surface to an inclined curved surface, and the stress that dominates the failure of the sample gradually changed from shear stress to tensile stress. Under the same normal stress, the larger the width of the test reserved gap, the smaller the measured peak shear strength value. With the increase of the width of the reserved gap, the cohesion of the samples obtained by direct shear test showed an increasing trend on the whole, but the change was small and relatively stable, while the angle of internal friction gradually decreased and changed obviously in a larger amplitude. The value of the width of the reserved gap in the test affected the shear strength, cohesion, and internal friction angle obtained in the test. Therefore, the width of the reserved gap should be reduced as much as possible in the rock direct shear test, while the quantitative value of the width of the reserved gap needs further research.
作者
陈红丽
曾亚武
刘伟
CHEN Hong-li;ZENG Ya-wu;LIU Wei(School of Civil Engineering,Wuhan University,Wuhan 430072,China;China Railway SIYUAN Survey and Design Group Co.,Ltd.,Wuhan 430063,China)
出处
《科学技术与工程》
北大核心
2020年第11期4495-4500,共6页
Science Technology and Engineering
基金
国家自然科学基金(41772308)。
关键词
大理岩
直剪试验
预留缝宽度
抗剪强度
破坏特征
marble
direct shear test
reserved gap
shear strength
failure characteristics
