Reinforcement mechanism of fissure grouting in earthen sites under pile-slurry combination

The reinforcement of fissure grouting with lime pile in earthen sites is effective, but the mechanism remains complex and unclear. A three-dimensional thermal-hydrological-mechanical model is established and calculated using finite element method, based on the theory of heat conduction and unsaturated permeability, combined with the non-isothermal hydration process of quicklime and the dynamic relationship of the lime pile, slurry, and rammed soil. By comparing the monitoring results of in-situ grouting test process and the finite element simulation results, the reinforcement mechanism is revealed. The results show that the quicklime in the lime pile and slurry reaches a high degree of reaction in a very short time, achieving 87% and 76% reaction degrees at 60 min, respectively. The physical fields in rammed soil around the fissure indicate that the slurry and lime pile act as the center, with values decreasing as the distance from the fissure increases. In this process, 80% of the water in the pile and slurry and 69% of the hydration heat are effectively utilized. After normalization, the quantitative effective influence ranges of temperature, water and expansion stress are determined to be 2.4 times, 0.7 times and 1.4 times the width of the fissure, respectively. This paper provides theoretical support for the new method of fissure grouting in earthen sites under pile-slurry combination.