Experimental study on cracking and shrinkage characteristics of granite weathered soil during drying process

To reveal the evolution mechanism of its cracking and shrinkage characteristics under dry climate conditions, the 3D pore distribution and shrinkage curves of granite weathered soil are obtained by the micron computer chromatography identification (μ-CT) scanning and shrinkage tests at different dehumidification time. Furthermore, the relationship between the rules of crack evolution and the characteristics of shrinkage is discussed. The test results show that the internal components of granite weathered soil can be divided into clay, quartz particles, iron cements and pores according to the 3D reconstruction model from the μ-CT scanning. The total porosity and content of connected cracks increase significantly with the elapse of dehumidification time. Under the drying effects, the pores with different equivalent aperture (R_e) increase to a certain extent, and the number of cracks with the equivalent aperture larger than 100 μm increases most obviously. The shrinkage curve of granite weathered soil can be divided into normal shrinkage, residual shrinkage and zero shrinkage stages. Besides, the ratio of surface cracks (R_sc) can be used to predict the shrinkage characteristics of soils, but the index of three-dimensional cracks obtained by the μ-CT scanning have better correlation with the real shrinkage of soils.