固化污泥固结渗透特性及孔隙变化试验研究

Experimental study on consolidation-permeability properties and pore size variation during consolidation

为了研究固化污泥在大变形固结过程中的渗透性特点，选用普通硅酸盐水泥（OPC）和硫铝酸盐水泥（SAC）作为固化材料，开展了14d龄期重塑样和原状样的固结渗透试验，得到了固化污泥在不同应力条件下的压缩、渗透规律；通过不同固结压力下的离心试验，分析不同固结应力下固化污泥的孔隙组成．试验结果表明，20％添加量内，固化污泥压缩系数均在1MPa-1以上，属于高压缩性土；固结应力在0—800kPa范围内时，固化污泥压缩系数随固结应力降低了两个数量级；固化污泥压缩、渗流过程存在明显非线性，在考虑渗透系数时，不适宜将渗透系数作为常数考虑；固化污泥固结过程中，大孔隙和中孔隙减少，而小孔隙反而增加，占总孔隙的50％以上．

To investigate the variation of permeability during finite strain consolidation, the sewage sludge was solidified by Portland cement （OPC） and sulphate aluminium cement （SAC） with a curing time of 14 d. The consolidation-permeability tests were performed to evaluate the behaviors of compression and hydraulic conductivity during consolidation. The pore size variation under different consolidation pressures was tested by centrifuge tests. The result shows that the solidified sludge is high compressive soil due to the fact that the coefficient of compression （αv） is up to 1 MPa-1. a v decreases by two orders of magnitude in the consolidation pressure range of 0-800 kPa. av and the permeability shows nonlinear relationship with the consolidation pressure. And the hydraulic conductivity is not suitable to be considered as a constant in calculation. During consolidation process, the proportion of macropores and mesopores decreases and micropores increases to 50% of the total pore space.