| Citation: | Ma Hongfa, Liu Qingbing, Li Jing. Effect of shrinkage characteristics of bentonite with different sand mixing rates and dry densities[J]. Bulletin of Geological Science and Technology, 2023, 42(6): 76-85. doi: 10.19509/j.cnki.dzkq.tb20220099
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Bentonite is a special soil with obvious expansion and shrinkage, and its strength change caused by shrinkage, accompanied by the formation of fissure has significant impact on the safety of engineering structures.Thereby, investigation on the shrinkage of bentonite is of great importance to engineering safety.
By carrying out the drying shrinkage test under constant temperature, combined with digital image technology, the effects of dry density and sand mixing rate on water evaporation, anisotropic strain and fissure during the drying shrinkage process of soil were studied.
The results showed that the drying shrinkage process of the soil can be divided into deceleration stage and residual stages. During shrinkage process, the higher the dry density and sand content ratio in soil sample, the less the water loss, the smaller the strain in each direction and the fewer the fissure created. The soil microstructure observed by scanning electron microscopy showed that the higher the dry density and sand content ratio, the more uniform and dense the soil microstructure, and the less the pores in soil. According to the selection of the soil sample shrinkage characteristic model, the T&D model has a better data fitting effect.
Experimental results evidence that increasing the sand addition rate and dry density is an effective means to reduce the shrinkage of bentonite.
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