Study On The Shrinkage Crack Of Dewatered Sludge As A Barrier Material In Landfill

Sanitary landfill disposal is one of today’s societies more widely used method of solid waste, solid waste disposal in urban and rural areas of which are widely used. Currently, in some parts of China, due to the sanitary landfill imperfect technology, many landfills around will cause varying degrees of pollution. To prevent leachate contamination of groundwater, impermeable layer is very necessary. Among the impervious layer design, the designs of impermeable soil layers have certain requirements. In landfill impermeable layer designs, due to the clay soil particles with a small, good adhesion characteristics such as low saturated permeable, so often used as a raw material impermeable layer of clay. But clay resources are very limited and costly, and therefore need to find a low-cost soil material used as raw material impermeable layer.The maximum particle size of dewatered sludge from the quarry is2mm, with the water content of24-25%, the liquid limit of38%and the plastic limit of17%. It is usually disposed into the landfill. This waste water sludge may be used as landfill material impervious layer. Because previous studies have shown that as long as the compression rate of95%compression conditions, but with20%of the maximum diameter of5-13mm gravel mixed waste sludge, soil samples will be able to make the saturated permeability coefficient is lower than the standard value1.0E-06cm/s. However, landfill impermeable layer, not only have lower saturated hydraulic conductivity, but also in the process of landfill operators long cracks as little as possible to reduce the possibility of leachate infiltration.In this study, the first in the initial moisture content of14.33%, while mixed with a diameter of5-13mm gravel soil samples were added fiber waste, in order to change the original soil samples due to the dehydration and drying shrinkage in the surface soil samples generate case cracks. There are three kinds of fiber materials are geotextile, geotextile fabric, fiber; lengths of8mm,16mm, and3cm. Three kinds of soil samples were added to the fiber content of0.5%,0.8%,1.0%and1.5%. In the experiment conducted among samples of surface soil moisture content of soil samples continuously, the number of cracks, the total length of the cracks, measuring the maximum width of the crack, in order to observe the occurrence and development of soil drying shrinkage cracks. Evaluation of the impact of fiber thus improving the soil drying shrinkage cracks. Secondly, the addition of0.5%of the fibers of two different materials saturated soil samples were measured permeability coefficient, the impact on the saturated hydraulic conductivity was measured after the addition of fiber in order. Finally, methods for measuring drying shrinkage cracks on the initial moisture field gravel field rate of14%,16%, and18%of the three soil samples were measured and evaluated drying shrinkage cracks.The results are as follows:(1)0.5%,0.8%of the length of8mm geotextile materials,1.0%of the length of16mm geotextile materials,0.8%of the length of3cm fiber materials can be effectively reduced drying shrinkage cracks in the surface soil samples generated and development. After adding these different fibers, drying shrinkage cracks formed in different forms. In the most significant effect was0.8%of the length of8mm geotextile material.(2) Adding the same proportion, fibers of different materials, and the impact of waste saturated hydraulic conductivity of soil samples produced are not the same. But the addition of two different fiber materials to a certain extent will reduce the saturated soil permeability rate. However,0.5%of the fiber material magnitude greater than the rate of0.5%saturated permeable geotextile material is reduced.(3) under field conditions, with20%of the6th gravel, compression ratio of90%, the waste soil sample initial moisture content of14%or16%, waste soil sample drying shrinkage cracks formed over the fine, waste water, soil-like shallow depth of penetration inside, one of the bases can be used as a reference project design.