垃圾土强度特性试验与双线强度包线研究

Tests on shear strength behavior and envelop of double lines of municipal solid waste

三轴试验和直接剪切试验是研究垃圾土强度特性的主要方法,通过人工配制垃圾土、标准砂掺纤维土、现场垃圾土重塑样的三轴试验和直接剪切试验,发现垃圾土的剪切应力应变(或位移)曲线表现为持续硬化型,在应变达到一定数值后曲线有锯齿状波动;经过国内相关试验成果的分析,得到垃圾土的强度参数主要受干密度的影响,且有较好的相关性。研究结果表明:垃圾土的强度包线可以用双线强度包线来表达,黏聚力和内摩擦角取决于是否填埋碾压;直接剪切试验结果介于三轴固结不排水和固结排水试验结果之间,且接近于三轴固结不排水试验结果;直接剪切试验更准确地模拟了垃圾团间的滑动摩擦特性,用直接剪切试验确定垃圾土的强度参数更合理;同时建议了三轴试验破坏应变和直接剪切试验破坏位移。

The triaxial and direct shear tests are the main methods to study strength behavior of municipal solid waste.By use of triaxial tests and direct shear tests on artificial solid waste,standard sand with textile and remolded municipal solid waste from field,the stress strain curves exhibit steady hardening and saw waving after certain strain is reached.Through the analysis of the existing test results in China,it is found that the dry density of solid waste is the key influence factor of strength and has good relation with the strength behavior.The results show that envelop of solid waste can be simulated by double lines,and that the cohesion and friction angle are dependent upon whether or not the solid waste is rolled.The shear strength of solid waste by direct shear tests is between that by CU triaxial tests and that by CD triaxial tests and is closer to that by CU triaxial tests.The direct shear tests are more accurate in simulating friction behavior between blocks of solid waste feasible to determine the strength parameters of solid waste.The failure shear strain in the triaxail tests and the displacement in the direct shear tests are suggested.