城市生活垃圾土的大型水平剪切试验研究

Experimental study on large scale horizontal push-shear test of municipal solid waste

垃圾土成分极不均匀,工程性质变化幅度大,小直径、小尺寸试样的试验结果难以反映垃圾土的宏观性质。为获取具有代表性的城市生活垃圾抗剪强度参数,采用大尺寸试样分析城市生活垃圾的组成,测定垃圾土的容重和含水率,利用自研的水平推剪试验装置进行大型水平推剪试验。研究结果表明:城市生活垃圾经过4 a降解,垃圾成分主要以土、建筑垃圾、塑料和玻璃陶瓷为主,厨余和纸制品等易降解部分基本降解完毕;生活垃圾的密度为1.06～1.25 g/cm3,小于普通土;生活垃圾的含水率为18.10%～25.63%。重塑垃圾土的抗剪强度指标为:c=41.94 kPa,φ=26.46°;饱和重塑垃圾土的抗剪强度指标为:c=47.96 kPa,φ=25.26°。浸水饱和后的垃圾土,内摩擦角略有降低,黏聚力有小幅增长;试验结果与大型三轴试验较为接近。

Due to heterogeneity of MSW,its mechanical properties change within a broad range.And it is difficult to gain its macroscopic property according to small size or small diameter test result.In order to obtain representative shear strength parameters of MSW,the components of MSW have been analyzed and its unit weight and water content have been mensurated with large scale tests.The large scale horizontal push-shear tests were carried out by using self-developed large scale horizontal push-shear test device.The test results indicate that after degradation of 4 years the major components of MSW are soil construction waste,plastic material,glass and ceramics,while kitchen waste,paper products and other easily biodegradable materials,have been already basically degraded.It is found that the density of MSW varies from 1.06 g/cm3 to 1.25 g/cm3,which is less than that of common soils.And the water content of MSW varies of 18.10%to 25.63%.The shear strength index of reconstituted MSW is as follows:c=41.94 kPa,φ=26.46°;and that of reconstituted MSW after soaking immersion is as follows:c=47.96 kPa,φ=25.26°.The friction angleφof reconstituted MSW after soaking decreases slightly,and its cohesion increases slightly.The value of the shear strength parameters obtained by large scale horizontal push-shear tests is close to the value of the shear strength parameters obtained by large scale triaxial shear tests.