Karst-Sandification Characteristics and Geotechnical Properties of Triassic Dolomite in Yuxi, China

As a special rock dissolution phenomenon, dolomite’s karst-sandification is widely distributed in the Triassic strata of the Yuxi area of Yunnan Province, China. In order to investigate the influence of karst-sandification on dolomite’s geotechnical geological properties, various methods were applied on Triassic dolomite in the study area from macroscope to microscope. Firstly, field investigation, microscopic identification, geochemical analysis and X-ray diffraction tests were used to inquire into the karst-sandification characteristics of dolomites. Furthermore, borehole sonic testing and a series of rock physical and mechanical tests were carried out to quantifying the effect of the karst-sandification on the Triassic dolomite. The results show that the Ca and Mg elements in dolomite were lost during karst-sandification by way of dissolution, whereas SiO2 was significantly enriched. After the karst-sandification, the integrity of the dolomite was reduced, and the elastic modulus, dry compressive strength, saturated compressive strength and tensile strength of the dolomite were reduced by 64.8%, 68.3%, 75.1% and 78.8%, respectively. Characterizing the karst-sandification and quantifying its influence on the Triassic dolomite can help establishing geological engineering regulations, and has great theoretical and practical significance to engineering construction in other similar areas.