针对现有大型拉拔直剪仪剪切盒不能进行土工合成材料之间或土工合成材料和颗粒材料之间直剪试验的状况, 在现有大型拉拔剪切仪的基础上, 根据试验要求和试验影响因素, 分别对该设备的上下剪切盒进行了改装. 在下剪切盒内放置可固定土工合成材料的Ⅱ字型板架,并通过在上剪切盒内放置内置挡板或可固定土工合成材料的钢板2 种方式, 使加载方式能实现柔性承压和刚性承压. 利用改装后的设备, 对光面土工膜-砂土界面、光面土工膜-土工布界面进行了直剪试验, 试验结果与其他同类材料直剪试验结果较为吻合, 证明对该设备的改装是合理可行的. 最后, 对加肋土工膜-砂土界面、加肋土工膜-土工布界面进行了一系列直剪试验,进一步验证了该设备改装后的稳定性.
The existing shear boxes of large pullout direct instruments cannot meet the experimental requirements of the geosynthetics-geosynthetics interface and the interface between geosynthetics and the granular material. To solve the problem, both upper and lower shear boxes are modified based on existing large instruments, test requirements, and factors affecting experiments. A grillage of type II is put into the lower shear box to fasten the geosynthetics. The upper shear box can realize a flexible bearing load by fixing the geotextiles to the bottom of inner plate, and a rigid bearing load with a rigid plate. After the modification, direct shear tests of smooth geomembrane and sand interface, smooth geomembrane and geotextile interface are carried out. The results agree with those obtained by other researchers, showing that the equipment modification is reasonable and feasible. A series of direct shear tests of the reinforced geomembrane and sand interface, and there inforced geomembrane and geotextile interface have been performed, verifying stability of the instrument after modification.
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