Swelling-Shrinkage Behavior Of Compacted Expansive Soil And Sand Mixed Specimen During Wetting-Drying Cycles

The swelling-shrinkage behavior of compacted expansive soils during wetting-drying cycles is a now hot spot as the need of dealing with the high level radioactive nuclear waste. This paper carried out on the GMZ-bentonite and sand mixed specimen wetting saturation-evaporative drying cycle test. The influence was caused by load and wetting-drying cycle path of which swelling-shrinkage deformation characteristics would be studied. The main contents are the following:(1) The research status deformation characteristics of bentonite and sand mixture the wetting-drying cycle test is summarized and it points out the significance of the subject.(2) The method of wetting-drying cycle test are summarized, pointing out paper selects the method of wetting saturation-evaporative drying cycle test; Through a series of routine physical testing including moisture content,limit moisture content test and free expansion rate test, physical properties of GMZ-bentonite and sand mixture were determined.(3) Wetting-drying cycle test under no load conditions, wetting-drying cycle test under load conditions, and wetting-drying cycle test under different path three types of test are done. Get the height of the specimens, the moisture content and porosity ratio the situation of changing, The specimen expansion and contraction deformation characteristics in the wetting-drying cycle test are analysised.(4) Under no load conditions, the specimen expansion of deformation is the first to become large then decreases with the increase of the number of cycles; specimen shrinkage is smaller with increasing number of cycles. Under load conditions, expansion and contraction deformation of specimen is smaller with increasing number of cycles. In both cases, the deformation of the change of the specimen wetting-drying cycle are mainly in previous. There are vertical load conditions, when the size of vertical load is not the same, the greater the vertical load deformation stability less numbei of wetting-drying cycle is required. During wetting-drying cycle, the heating of the magnitude different specimen of wetting-drying cycle deformation development trend is not affected, but the low level of heat drying, the more number of cycles would be needed to make the deformation stable. After deformation of the specimen is stable, to change the degree of drying of the specimen, the deformation trend of sample would be not changed, but the fluctuation range is changing. GMZ-bentonite deformation of wetting-drying cycle test can be decomposed into two parts and the both are reversible and irreversible, when the initial conditions are not the same, irreversible deformation may be shrinkage or swelling. With a picture record and analyze the development of which in the absence of load and no load conditions specimen’s fractured..