针对土工合成材料土中与空气中抗拉性能的差异性,研制了一台土工合成材料土中拉伸试验机。该试验机采用可移动套筒以保证测试材料一直处于土体中,减少甚至消除填土与夹具之间的摩擦,使测得的试样受拉力值更为精确;采用双光杆滑动轨道以保证夹具与套筒的低摩阻定向移动。该试验机能进行土工合成材料土中、空气中以及侧限拉伸试验,还能进行拉拔和蠕变试验。采用该试验机进行了5种土工合成材料空气中、土中拉伸试验及侧限拉伸试验。结果表明,土工合成材料在筋土相互作用下的抗拉强度受筋材与土体间摩擦的影响较小,而侧限约束是造成土中拉伸与空气中拉伸巨大差异的主要原因;分别得到了空气中拉伸强度与土中拉伸强度、侧限拉伸强度的量化关系式,可由较容易测得的空气中拉伸强度直接求得土中拉伸强度或侧限拉伸强度,便于工程利用时参考。
Abstract
In view of the difference of tensile properties between in-soil and in-air geosynthetics, a tensile testing device for geosynthetics in soil was developed. Movable sleeve was adopted in the device to keep the geosynthetics in soil, which addressed the interference problem caused by the friction between the filling and the fixture; the friction of soil against the sleeve was also considered. Sliding track of double smooth rod was designed to ensure the low-friction directional movement of the fixture sleeve, and also avoided the eccentric stress of geosynthetic material in the tensile process. The upper and lower air pressure bags kept the geosynthetics in close contact with the soil and withstand confining pressure. The device could accomplish tensile test of geosynthetics both in soil and in air, as well as confined tensile test, creep test and in-soil pullout test. The device was applied to the in-air tensile test, in-soil tensile test and confined tensile test for five different types of geosynthetics. Results suggest that tensile strength was slightly affected by the friction between geosynthetics and soil; while confining pressure is the major cause of the huge difference between in-soil and in-air tensile strength. The quantitative relationship between the in-air and in-soil tensile strength or the confined tensile strength was obtained for engineering reference. The in-soil tensile strength or confined tensile strength can be deduced through the in-air tensile strength.
关键词
土工合成材料 /
抗拉强度 /
土中拉伸 /
空气中拉伸 /
量化关系 /
侧限拉伸
Key words
geosynthetics /
tensile strength /
in-soil tensile /
in-air tensile /
quantitative relationship /
confined lateral tensile
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基金
国家自然科学基金项目(42067044);广西自然科学基金项目(2018GXNSFAA294130);桂林电子科技大学雷电竞rayget下载
创新计划项目(2020YCXS123)
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