土工膜作为一种防渗材料已广泛应用于工程和环保领域,但在施工铺设过程中的损伤会降低其抗剪强度。利用大型直剪仪进行土工膜(GM)与膨润土防水毯(GCL)界面多级加荷剪切与直接剪切试验,探究加载对土工膜抗剪强度的影响。试验结果表明多级加荷剪切峰值强度较小于直接剪切峰值强度,2种剪切方式界面均表现出明显的应变软化特性;正应力为7.1~52.1 kPa时,多级加荷剪切峰值强度和残余强度分别与直接剪切峰值强度和残余强度均较为接近;大正应力下的重复剪切对土工膜损伤有较大影响,当正应力大于102.1 kPa,多级加荷剪切峰值摩擦角降低了7.05°,残余摩擦角降低了3.09°。
Abstract
As an impermeable material, geomembrane (GM) has been widely used in engineering and environmental fields, but the damage during construction will reduce its shear strength. In view of this we conducted multilevel loading and direct shear tests on GM/GCL (geosynthetic clay liner) interfaces using a large size direct shear apparatus. Results show that the peak shear strength under multilevel loading is much lower than that under direct shear, and obvious strain softening of the interface occurs under both shear modes; the peak shear strength and residual strength under multilevel loading are close to those under direct shear when the normal stress is from 7.1 to 52.1kPa; repeated shearing under large normal stress has great damage on geomembrane which leads to a loss of 7.05 ° in terms of peak friction angle and 3.09 ° in terms of residual friction angle when the normal stress is greater than 102.1kPa under multilevel loading.
关键词
土工膜 /
GCL /
多级加荷 /
剪切强度 /
应变软化
Key words
geomembrane /
GCL /
multilevel loading /
shear strength /
strain softening
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