Laboratory Physical Model Test of Microbial Siliceous Sand Pile in Soft Soil Foundation

Microbial silica sand pile is a kind of energy-saving and environmentally friendly small diameter short pile prepared by microbially induced calcium carbonate precipitation (MICP) technology. In this study, an indoor model box simulation test is conducted to analyze the bearing performance advantages of microbial siliceous sand piles, the distribution characteristics of pile side friction resistance, and the load transfer characteristics. The following conclusions are drawn: (1) The siliceous sand piles obtained through microbial solidification technology exhibits a good curing effect, with the unconfined compressive strength of the piles reaching 436.8 kPa. (2) The bearing capacity of single pile of microbial silica sand increases with pile length. When the pile length L is 560 mm, the ultimate bearing capacity of single pile reaches 0.81 kN, with a settlement of pile top at 20.06 mm. Upon insertion into the bearing layer, the bearing capacity of the single pile can reach 1.06 kN, representing a 34.6%. (3) The axial force of microbial coral sand pile decreases with increasing depth. Due to the short pile, the lateral friction resistance of the pile is positive, and the friction resistance increases rapidly in the 0-20 cm section, demonstrating noticeable soil squeezing effect. As the 20-40 cm section decreases from increase, the calcium carbonate skeleton is liable to break, resulting in a decrease in horizontal effective stress around the pile and a slowdown in the increase of pile side friction. (4) The ultimate bearing capacity of the soft soil-microbial silica sand pile composite foundation is approximately 41.3 kPa, 24.8% improvement over that of the untreated soft soil foundation. The test results can lay the groundwork for the engineering application of microbial siliceous sand pile.