Research On The Composite Foundation Compsi-ted By Lime Soil Cushion And Anti-seepage Film And Its Application In Collapsible Loess Area

As a kind of problem soil, one of the most important engineering properties of loess is collapsibility. A lot of research on the mechanism of collapsibility loess have been done in domestic and foreign academia, and various hypotheses were putted forward, which provide theoretical support for dealing with collapsible loess foundation. With the development of economy, more and more engineering constructions are being built in collapsible loess area, that facing a common problem-how to deal with the collapsibility of loess. In current engineering practices, cushion method, lime-soil compaction pile method, immersion method and chemical grouting method, etc, have been used to conduct collapsible loess foundation, these methods have their limitations, especially in the big thickness collapsible loess regions. But, as a common impermeable material, composite geomembrane have been used in subgrade engineering, reservoir impermeable engineering, achieved good anti-seepage effect and economic benefits. Based on the comprehensive treatment effect of cushion and composite geomembrane, the application of lime soil cushion layer and anti-seepage film in loess area is studied in this paper.The deformation of collapsibility loess foundation is mainly caused by rain infiltration or leaky plumbing. Under natural conditions, Rainfall is inevitable, based on the theory of unsaturated soil mechanics, the change of infiltration path of foundation, that affected by rainfall infiltration, is studied in this paper, and the consequence can provide advice for the design of width and depth of anti-seepage film. What’s more, the stress-strain characteristics of lime soil cushion and anti-seepage film composite foundation under the strip load, and its application scope is discussed, and figuring out that ratio of modulus of loess and lime soil cushion which is not greater than0.18is appropriate, and can improve the foundation bearing capacity significantly, an The stress and strain characteristics of composite foundation under different load,different strip width and different thickness of lime soil cushion,also be studied. On the basis of these research, the stress and strain characteristics of composite foundation dealed with local processing is discussed, figuring out that when the width of bedding strip processing is3times of the bottom of strip, can allow full play to the enhanced effect of lime soil cushion layer.