土工膜/土工织物界面大型斜坡模型试验研究

Large-scale ramp model tests on geomembrane/geotextile interface

复合衬垫系统广泛应用于垃圾卫生填埋场,是防止渗沥液污染物渗漏扩散的重要屏障。在垃圾重力及沉降作用下易造成斜坡上复合衬垫系统拉伸破坏或沿其界面产生滑移而失稳。目前,由于缺乏对复合衬垫系统内部剪力传递机理的认识,仍难完全解决以上两大岩土工程问题。因此,设计并采用复合衬垫系统大型斜坡模型试验装置开展了其内部剪力传递机理的研究。该装置通过砂袋加载模拟填埋过程,采用手拉葫芦为核心的滑移控制系统再现了土工膜/土工织物界面的渐进累积破坏过程。试验结果表明:当外部剪力小于峰值强度时,界面不会进入残余状态,上覆的土工合成材料锚固端的拉力也非常小;但当外部剪力超过界面峰值强度时,界面就会逐渐进入残余状态,并最终达到残余强度。同时,薄弱界面上覆的土工合成材料锚固端的拉力也显著增加,严重时甚至被完全拉断。

Composite liner systems are widely used in waste disposal landfills to minimize the potential contamination of the geo-environment. The shear stresses exerted by the gravity and settlement of waste may lead to tensile failure or sliding instability along the interfaces. Due to lack of understanding of shear stress transfer mechanism, the above engineering problems are still often occurring. A large-scale ramp model test apparatus is designed to study the shear stress transfer mechanism. Landfill process is successfully simulated by stacking sand bags, and progressive slope failure along the geomembrane/geotextile interface is revealed by the sliding control system. The test results show that when the shear stress induced by the vertical loading is less than the peak interface shear strength, the interface strength will not fall into a residual strength. However, when the shear stress exceeds the peak interface shear strength, the interface strength will quickly fall into a residual strength, which will result in sharp increase of the tension in the geotextile, and if it is serious, the geotextile will be completely broken.