聚苯乙烯泡沫颗粒轻质混合土(EPS混合土)具有质轻、强度可调可控及环境友好等特点,作为复合土工材料常用于地基处理.设计并完成了小比尺室内模型试验以研究EPS混合土处理桥台软弱地基的效果.采用粒子图像(PIV)测速技术监测桥台地基的位移场,对比分析了软土地基桥台背后回填砂土、水泥土,以及2%、3%和4%3种不同配比的EPS混合土时的台背侧向土压力及地基土变形特征.结果表明:与传统的砂土填料相比,EPS混合土可以有效减小台背侧向土压力,在本文试验配比范围内,台背侧向土压力随着EPS颗粒含量的增加而减小;EPS混合土可显著减小回填土表面沉降量,其不均匀沉降也较砂土填料大为改善,地表的沉降量与测点距桥台的距离之间趋向于线性关系;回填EPS混合土时,填土表面出现的不均匀沉降主要是由于桥台地基软土层在荷载作用下出现趋向桥台底部的滑移变形,从而引起整体刚度较大的回填EPS混合土层倾斜.工程实践中,应对EPS混合土的回填深度进行综合考虑.%Expanded polystyrene ( EPS ) composite soil has many advantages such as light weight, controllable strength,and environment-friendly material,so it is usually used as the composite geomaterial to treat the soft soil. A small-scale laboratory model test was designed and conducted to study the reinforcement effect for the soft soil supporting an abutment retaining EPS composite soil. The displacement filed of the model soil was obtained by particle image velocimetry ( PIV ) measurement technique. The earth pressure behind the abutment and the deformation of the model soil were comparatively analyzed for sand,cemented soil and EPS composite soil with three types of mixing ratios 2%,3% and 4% EPS. The results showed that EPS composite soil can effectively reduce the earth pressure in contrast to traditional sand backfill,and the earth pressure reduced with the increase of EPS content in the ratio range of this paper.EPS composite soil significantly reduced the settlement of backfill surface and the differential settlement was greatly reduced compared with sand backfill. The relationship between the surface settlement and the distance from the measuring point to the abutment tended to be a linear one.The differential settlement of the backfill surface for EPS composite soil was resulted from that the untreated soft soil slips to the bottom of the abutment under the loadings,thus leading to the leaning of EPS composite soil with a higher entire rigidity. In practical application, the backfill depth of EPS composite soil should be considered comprehensively.
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