防止直剪试验剪切盒倾斜的方法及初步验证

Method and Preliminary Verification for Preventing Shear Box Tilt of Direct Shear Test

受直剪仪自身缺陷的影响,常规试验试样剪切过程中剪切盒会发生倾斜。对比研究剪切盒倾斜与不倾斜状态下的抗剪强度,提出一种防止剪切过程中剪切盒倾斜的方法,对不同干密度和不同含水率试样进行直剪试验,将试验结果与常规试验下的抗剪强度进行对比分析。结果为:相同含水率下,抗剪强度随干密度的增大而增大;相同干密度下,抗剪强度随含水率增加而减小;2种试验条件下抗剪强度曲线走势一致,防止剪切盒倾斜条件下抗剪强度、内摩擦角和粘聚力均高于常规试验条件下的试验结果。防止剪切盒倾斜方法增加了竖向荷载,导致抗剪强度偏高;防止剪切盒倾斜的试验方法操作简单、结果具有可靠性,为不同研究结果的对比提供相同试验条件,具有一定的实用价值。

Influenced by the defects of the direct shear apparatus,the shear boxes tilts in the process of the conventional test. The shear strength under the condition of tilted and non tilted was studied. This paper presented a method to avoid the tilt of the shear boxes in the shearing process,direct shear tests were done in different dry density and moisture content,and the results have been compared with that analyzed by conventional test. The shear strength increased with the increase of dry density under the same moisture content. At the same dry density,shear strength decreased while the moisture content increased; The shear strength curved under two different kinds of shear conditions coincided well with each other. Strength parameters（ angle of internal friction and cohesion values） under the condition of preventing tilt were higher than those obtained from conventional test. Limiting shear box tilt,which increased the vertical load,resulted higher shear strength; The method provided a same test condition for the comparison of results obtained from different studies. Due to the advantages of simple operation,reliable result,the method for preventing shear box tilt has certain research value.