MBT垃圾的三轴试验结果

采集杭州天子岭垃圾填埋场的MBT垃圾,在环境土工实验室进行了成分分析、试样制备、三轴快剪、固结快剪和慢剪试验,对MBT垃圾的剪切强度特性进行了系统地研究。结果表明:①MBT垃圾的组分主要以塑料、纺织物、玻璃、灰土和无法识别的材料为主。②随着轴向应变的增大,偏应力逐渐增大,轴向应变超过30%后仍没达到峰值,是一条应变硬化曲线。③得到了三轴快剪、固结快剪和慢剪试验条件下抗剪强度参数(黏聚力和内摩擦角)的取值范围。④MBT垃圾的抗剪强度参数与轴向应变的关系可拟合为直线关系,建立了抗剪强度参数与轴向应变的线性关系表达式。⑤MBT垃圾的应力–应变关系符合邓肯–张模型,得到了模型参数a,b的取值范围,建立了模型参数a,b与围压的幂函数关系表达式。研究结果可为MBT垃圾填埋场的稳定性分析提供理论基础。

Shear strength behavior of mechanically-biologically treated waste in triaxial tests

To study the shear behavior of mechanically biologically treated (MBT) waste systematically, the samples from Tianziling landfill (Hangzhou, China) are collected, and several tests are carried out in an environmental and geotechnical laboratory, such as composition analysis, sample preparation, triaxial unconsolidated-undrained (UU), consolidated-undrained (CU), and consolidated-drained (CD) tests. These tests reveal that the main components of the MBT waste include plastics, textiles, glass, fines, and unidentified materials. The deviatoric stress gradually increases with the increasing axial strain, and no peak value is attained even when the axial strain exceeds 30%, indicating a strain hardening behavior. The UU, CU, and CD tests reveal the ranges of the shear strength parameters (cohesion force and internal friction angle). The relationship between shear strength parameters and axial strain is linear, and the fitting equations are obtained. The stress-strain relationship of the MBT waste conforms to that of the Duncan-Chang model, and the ranges of the model parameters (a and b) are obtained. Further, a power function relationship is established between the model parameters and the confining pressure. These results can provide a theoretical basis for the stability analyses of MBT waste landfills.