高有机物含量新鲜生活垃圾压缩与渗透相关特性试验研究

Experimental study on the compression and permeability combined test of fresh municipal solid waste with higher organic matter

为研究垃圾填埋场渐进堆高过程中垃圾的渗透特性及变化规律,考虑垃圾压缩过程中压力、压缩时间、压缩应变及密度变化等因素的影响,采用自主研发的压缩与渗透联合测定试验仪器,在环境土工实验室,对31个试样180组高有机物含量新鲜生活垃圾进行系统的室内试验研究。压缩试验过程采用6级压力(0,25,50,100,200,300 k Pa),每级压力采用6个不同的压缩时间(0,1,2,6,12,24 h);渗透试验过程考虑6个水力梯度。试验结果表明:(1)存在临界水力梯度,只有当水力梯度超过临界水力梯度后,垃圾才会发生渗流。(2)渗透速率与水力梯度的关系可拟合为一条直线,符合达西渗透定律;(3)渗透速率与压力的关系可以拟合为指数函数,拟合系数大于0.93;(4)渗透系数的对数与密度的关系可以拟合为一条直线,拟合系数大于0.98,给出了直线关系表达式;(5)渗透系数的对数与压缩应变的关系也可拟合为一条直线,拟合系数大于0.97,给出了直线方程。试验结果可为垃圾填埋场的渗透性分析提供参考。

To investigate the permeability of fresh municipal solid waste（MSW） during the process of gradually filling, a self-made permeability and compression combined test apparatus was used to perform 180 permeability and compression combined tests with 31 fresh MSW samples in geo-environmental laboratory,and the effects of pressure,compression time,compression strain and density were considered. Six different vertical pressures of 0,25,50,100,200 and 300 k Pa were applied,and six compression times were 0,1,2,6,12 and 24 hours,were selected for every vertical pressure during the compression process. Besides,six hydraulic gradients were applied. Testing results showed that：（1） There exists a critical hydraulic gradient for the permeation of fresh MSW,the permeation will start only after the hydraulic gradient has reached the critical hydraulic gradient.（2） The relationship between permeation rate and hydraulic gradient can be formulated as a linear function that corresponds to Darcy＇s law.（3） The relationship between permeation rate and pressure can be formulated as an exponential function with the correlation coefficient greater than 0.93.（4） The relationship between logarithmic permeability coefficient and density can be formulated as a linear function with the correlation coefficients greater than 0.98. The equations that express this linear relationship are provided.（5） The relationship between logarithmic permeability coefficient and compression strain can also be formulated as a linear function,and the correlation coefficients are greater than 0.97. The equation express this relationship is also provided. The test results from this study can be used as reference for the permeability analysis of a municipal solid waste landfill.