Characteristics of Sandification Dolomite and Effect on In-Situ Bearing Capacity of Pile Foundation

A group of Carboniferous and Permian dolomites are widely developed in the Tianxingzhou belt of carbonate rock in Wuhan. Drilling revealed that the dolomite has different degrees of sandification, which has caused many difficulties to the exploration, design and construction. By means of in-situ drilling sampling, saturated uniaxial compression test, thin section identification, etc., the physical and mechanical properties of sandification dolomite were analyzed, and the classification table of dolomite sandification degree was compiled. Combined with the in-situ load test data of 14 sets of bored test piles, the characteristics of pile foundation bearing capacity and the effect of pile side and pile tip resistance in sandification dolomite stratum are analyzed. The research results show that when layer ⑤1 is used as the supporting layer, the ratio of length to diameter is inversely proportional to the end resistance. When layer ⑤2 is used as the supporting layer, the end resistance ratio has a strong correlation with the depth-diameter ratio, but has little correlation with the length-diameter ratio. In general, in the sandification dolomite formation, the effect of the pile tip resistance is low. In comparison, the pile type with d = 800 mm in layer ⑤1 fully sandification dolomite stratum, the pile tip resistance is better. The pile foundation can achieve greater bearing capacity and is more suitable for the proposed construction in this stratum.