Abstract: In order to investigate the effects of structural rupture and dissolution on dolomite sanding in Yuxi section of central Yunnan water diversion project, indoor static dissolution experiments of dolomite under different acid solutions and temperatures were carried out. Further study on the sanding mechanism of dolomite in Yuxi section of central Yunnan water diversion project was conducted by means of SEM, XRD and EDS energy spectrum analysis. The dissolution test results show that crystal structure and temperature of dolomite are the main factors affecting dissolution rates of dolomite, and microstructures of rock samples after dissolution becomes obviously different from that of rock samples with higher degree of sanding and being undissolved. The quantitative analysis of the microstructure of PCAS software reveals that the closer the rock sample is to the fault, the more seriously broken the rock sample becomes, and the higher the probability entropy, the higher fractal dimension and apparent porosity. The results of XRD and EDS spectra show that the mineral composition of dolomite samples with different degrees of sanding does not change obviously. For the study of regional sandy dolomite strata, dissolution is not the main factor of sanding, but tectonic fracture is the main controlling factor of dolomite sanding.

Key words: dolomite, sanding, tectonic fragmentation, dissolution, microstructure