Research On Several Key Technical Problems Of Expansive Soil Canal Slopes

The expansive soil has much effect on the project, and is also one of important causes of the geological hazard. Since it made a lot of great damage and project problems, the research and treatment of the expansive soil has become global technical problems in engineering and engineering geology. As a important decisions project of China, the South-to-North Water Diversion Middle Route Project (denotes Middle Route Project in the following) has 1432 km long, in which about 340 km long areas are expansive rock and soil slopes. Based on the engineering characteristics of South-to-North Water Diversion project, the research on several key technical problems of expansive soil Canal Slopes, such as classification, engineering characteristics, failure mechanism, treatment measures and so on, has important theoretical meaning and practical significance. In this paper, the current research situation on expansive soil's physical and mechanical characteristics, failure mechanism of canal slopes and treatment ways are summarized firstly. and gained the classification results of expansive soils in Middle Route Project. Secondly, according to the limitation of current classification approach, a new multi-indexes classification system on expansive soils has developed, Then the laboratory test and in-situ test on physical mechanical, swell-shrinking, permeability and atmospheric effects of expansive soils carried out, and fluid-solid coupling analysis method, which involved swelling behavior, and treatment measures of canal slopes of Middle Route Project construction developed. The main research contents and results include:In chapter 2, experimental study on the typical expansive rock and soil sampling's engineering properties investigated. Atmospheric effect depth comparative analysis of expansive soil's swell-shrink characteristics and seepage properties between undisturbed sample and remodeling sample has made.In chapter 3, based on the rough Set theory, important analysis of expansive soils classification indexes carried out, and developed a new multi-indexes classification system, according to the disadvantages of current classification methods.In chapter 4, the failure mechanism of expansive soils canal slopes studied, and revealed the failure mode by in-situ test, developed the fluid-solid coupling analysis method, which involved swelling behavior, calculated the safety factor by strength reduction finite element method. The validity of new method is testified by large indoor model test and field test.In chapter 5, the treatment measures of expansive soil canal slopes are studied roundly by indoor-test and field-test. The comprehensive evaluation on engineering effect of these methods has made. Finally, the treatment schemes to expansive soil canal slopes in South-to-North Water Diversion project put forward.Conclusions and prospects are put in Chapter 6.