石英云母片岩在曼家寨东帮采场普遍发育,研究其抗剪强度对于该边坡的稳定性评价具有重要的意义.采用堆载法,选取不同高程下的四个试点进行原位直剪试验,获得石英云母片岩的剪应力与剪切位移关系曲线,采用最小二乘法对不同高程下片岩的抗剪强度指标进行计算,得到对应的黏聚力c与内摩擦角φ.试验结果表明,曼家寨东帮采场石英云母片岩剪切强度随着法向应力的增大而增大,τ与σ呈明显的线性变化趋势,相关系数为0.968～0.998.高程H对石英云母片岩抗剪强度参数有着重要的影响,随着高程的增加,黏聚力c有逐渐降低的趋势,而内摩擦角φ变化无明显特征,即高程H对黏聚力c的影响程度大于其对内摩擦角φ的影响程度.%There are large areas of quartz-mica schist existed in east slope of Manjiazhai,the shear strength properties of the schist are very significant to the stability analysis for this slope.In this paper,the authors selected four locations of different height for in-situ direct shear tests that was carried out by using the heap-loading method.Relationship curves between shear stress and shear deformation for quartz-mica schist were obtained.The shear strength parameters were calculated using least square method,and the corresponding cohesion c and internal friction angle φ were obtained.The results show that the shearing strength of the quartz-mica schist in the east slope of Manjiazhai increased with the increase of the normal stress,the τ and oσ show a linear trend,and the correlation coefficient is between 0.968 and 0.998.Elevation H has an important effect on the shear strength parameters of quartz-mica schist,with the increase of elevation,the cohesion c tends to decrease gradually,while the change of internal friction angle φ has no obvious feature.The effect of elevation H on cohesion is greater than that on internal friction angle.
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