南疆绿洲区含残膜砂土固结变形特性试验研究

Experimental Study on Consolidation Deformation Characteristics of Sandy Soil with Residual Agricultural Film in Oases Area of Southern Xinjiang

南疆绿洲区受到风沙堆积和河流沉积耦合作用,致使表层土体多为含有细粒土的砂;与此同时,农业生产导致表层砂土中大量农膜残留。农膜残留不仅污染环境,同时也改变了土的固结变形性能。为了定量研究残膜残留量及细粒土含量对砂土固结变形特性的影响,选取南疆三组不同细粒土含量砂土,分别掺入不同质量比残膜,形成人工配置含残膜土。通过击实和固结试验得到了如下结论:(1)砂土干密度随着残膜含量的增加先增加后降低,转折残膜含量为0.05%~0.1%,其最大干密度相较于素土提高了0.03%~0.04%;(2)含残膜土受荷后具有较高的压缩性,其压缩应变量可达素土的4~5倍;(3)相同荷载下,含残膜土的压缩系数大于素土,但随着荷载的增加,两者差异逐渐减小,当荷载达400kPa时,差值仅为0.00005~0.0001 k Pa^(-1);(4)细粒含量对含残膜土的固结变形特性影响不大,粉土质砂压缩系数略大于含细粒土砂,两者相差0.000 08~0.000 2kPa^(-1)。

The Southern Xinjiang oasis is influenced by the combination of wind-sand accumulation and river deposition,which lead to the surface soil is mostly sand containing fine grained soil.At the same time,agricultural activities result in a large amount of agricultural film residue in the surface sandy soil.The agricultural film residues not only pollute the environment but also change the consolidation deformation properties of soil.In order to quantitatively determine the effects of the amounts of agricultural film residue and fine particles on the consolidation deformation characteristics of sand soil,three groups sand soil of different fine particles content mixed with different mass ratio film residue were selected to measure dry density and consolidation deformation.The conclusions are these as follows.①The dry density first increases and then decreases with the increase of agricultural film residue content,the content of the transformation residues is between 0.05%～0.1%,and the maximum dry density increased by 0.03%~0.04%compared with pure soil;②The compressibility of soil with residual agricultural film is 4~5 times higher than that of pure soil;③The compression coefficient of soil with residual agricultural film is far greater than that of pure soil,but as the load increases,the difference between the two gradually decreases,and when the load reaches 400 kPa,the difference is only between 0.000 05～0.000 1 kPa-1;④The consolidation deformation characteristics of soil with different fine grain content are similar,the compressive coefficient of SM is slightly larger than that of SF,and the difference between them is 0.000 08~0.000 2 kPa^-1.