中高龄期模型固体废弃物三轴试验与强度特性分析

Triaxial tests and analysis of shear strength of municipal solid waste at medium and high ages

为揭示中、高龄期城市固体废弃物(MSW)的力学特性,通过向石英砂、高岭土混合物中加入不同质量比的草炭人工配制模型固废试样,开展了三轴固结排水剪切和固结不排水剪切试验研究。试验结果表明,中高龄期模型固废均表现出持续硬化的应力应变特性,固结排水试验中中龄期模型固废的体变略大于高龄期,固结不排水试验中高龄期模型固废的孔压略高于中龄期。采用15%轴向应变对应的剪应力描述其抗剪强度,并根据Skempton有效应力原理,通过对比固结排水试验和固结不排水试验结果,得出了固废的孔隙水压力折减系数和抗剪强度参数,孔隙水压力折减系数随龄期增加而增大,高龄期模型固废得到的黏聚力低于中龄期,高龄期固废得到的内摩擦角则高于中龄期。

In order to investigate the mechanical property of municipal solid waste(MSW) at medium and high ages, the artificial model MSW was made up by adding appropriate mass ratio of turf into the mixture of Quartz sand and kaolin clay, and then a series of consolidated drained and undrained triaxial tests were conducted. The tests results showed that the stress-strain of MSW at both high and medium age demonstrate continuous hardening characteristics during shear. The volumetric strain of medium age MSW in drained tests is little bigger than that of high age, the pore water pressure of high age MSW in undrained test is bigger than that of medium age. When the shear stress at 15% axial strain is adopted as the shear strength, the reduction coefficient of the pore water pressure and shear strength parameter were obtained by according to the Skempton's principle of effective stress. The reduction coefficient of the artificial model MSW is shown to increases with the age, the cohesion of the artificial model MSW decreases with the age, while the friction angle increse with the age.