新鲜生活垃圾压缩与直剪联合测定试验研究

在环境土工实验室人工配制了新鲜生活垃圾,采用大型压缩与直剪联合测定仪器,对96个新鲜垃圾试样进行了压缩变形、剪应力及剪应变联合测定试验,研究了垃圾的压缩变形对强度的影响及规律。试样的初始孔隙比分别为2.1、2.5、2.9,试样竖向压力分别为25、50、100、200 k Pa,每级压力作用下的时间分别为0、0.25、0.5、1、2、6、12、24 h。试验研究表明,(1)不同压缩时间下剪应力与剪应变的关系符合双曲线模型,模型参数a在0.028⁰.144之间,参数b在0.0120.144之间,参数b在0.012⁰.024之间;(2)不同竖向压力及不同剪应变限值下抗剪强度与竖向压缩应变(压缩时间)的关系可以拟合成多项式的形式,得到了参数的拟合值及相关系数,相关系数在0.630.024之间;(2)不同竖向压力及不同剪应变限值下抗剪强度与竖向压缩应变(压缩时间)的关系可以拟合成多项式的形式,得到了参数的拟合值及相关系数,相关系数在0.63⁰.98之间;(3)不同初始孔隙比的抗剪强度与竖向压力的关系符合库仑定律,得到了不同剪应变限值的抗剪强度参数,黏聚力在11.10.98之间;(3)不同初始孔隙比的抗剪强度与竖向压力的关系符合库仑定律,得到了不同剪应变限值的抗剪强度参数,黏聚力在11.1³4.2 k Pa之间,内摩擦角在11.2°34.2 k Pa之间,内摩擦角在11.2°³0.6°之间。

Experimental study of compression and direct shear combined test of fresh municipal solid waste

To investigate the coupling properties and laws of the deformation and the shear strength of fresh municipal solid waste (MSW), the compression-direct shear combined tests have been carried out by using large-scale combined test apparatus of compression and direct shear. Ninety-six fresh municipal solid waste samples were prepared in geoenvironmental laboratory. The initial void ratios of the samples were selected as 2.1, 2.5 and 2.9. Four different vertical pressures 25, 50, 100, and 200 kPa, were chosen; and the compression times for every vertical load were 0, 0.25, 0.5, 1, 2, 6, 12, and 24 hours, respectively. The testing results show that: (1) The relationship between shear stress and shear strain under different compression times is in conformity with a hyperbolic model; model parameter a varies from 0.028 to 0.144; and model parameter b varies from 0.012 to 0.024. (2) A multinomial model can be used to express the relationship between shear strength and compression strain (compression time) under different vertical pressures and different limit values of shear strain, the values of model parameters are given, and the correlation coefficient of the model is found in the range of 0.63-0.98. (3) The relationship between shear strength and vertical pressure applied on the sample under different initial void ratios complies with Coulomb’s law. Besides, shear strength parameters of the MSW are obtained; the cohesion force varies from 11.1 to 34.2 kPa; and the internal friction angle varies from 11.2 to 30.6 degree.