Restoring Of The Expansive Soil Properties And Strength Characteristics Of Experimental Research

The remolded soil is usually involved in expansive soil engineering, such as constructing embankment, slope design and so on. It is important for us to study the expansive scale, characteristics of shrink-swell and strength of the remolded expansive soils so as to help the construction of roads and railways, to improve expansive soil foundation and to design the expansive soil slope.The characteristics of shrink-swell and strength of the remolded expansive soils are studied in this thesis , according to a series of experimentations in room, in which light consolidation apparatus , compression apparatus and routine direct shear apparatus are applied. The main achievements in this thesis can be obtained as follows.1. A survey for many literatures on classification of expansive soil from the domestic and international is given. Through the contrast of the current method, pointing out the merit and shortcoming of every kind of method; And we also give classifications of the soil in the area of Chang(de)-Zhang(jiajie) superhighway and Nan(ning)-You(yiguan) superhighway by the method of fuzzy mathematics and standard moisture absorption water content of soil. All these provide more data for the engineering construction in these expansive soil areas in future.2. The swelling-shrinkage mechanisms and influence factors of remolded expansive soils are summarized, Based on lots of laboratory tests of Nan(ning)-You(yiguan) expansive soils,the relationship between shrink-swell and time of expansive soils is researched. The similarities and differences between shrink and swell are found. The quantitative correlation between deformation magnitude with different original water content and dry densities is explored.3. The direct shear tests of remolded expansive soils are performed for different dry densities and original water content with different stresses. The stress-strain relation and strength index of Nan(ning)-You(yiguan) remolded expansive soils is studied. The feature of the peak value strength and residual strength of expansive soils under different initial stations(original water content, dry densities and above acting pressure) is recognized. The quantitative rules of the cohesion and soils angle of internal friction to original water content and dry densities is developed.4. Through the comparative experiments of geotechnical engineering of red clay and expansive soil, consider that their geotechnical engineering properties are quite different because of the differences of substance composition and microstructure, though there are also some similarities between them. Red clay and expansive soil should be distinguished for treatment in engineering practice.5. An in-situ monitoring and finite element simulation about the deformation of the expansive soilroadbed in construction is given.The deformation behavior of the settlement and lateral displacement during the course of the constucuions is researched. All these provide more data for the engineering construction in these expansive soil area in future.