Study on Load Transfer Mechanism of Pile-Supported Embankment Based on Response Surface Method

Based on the improved three-dimensional finite element model, this paper studies the load transfer mechanism of pile-supported reinforced embankments. The model uses an elastic medium to replace the soft soil subgrade, which reduces the calculation depth of the subgrade and improves the calculation efficiency of the model. The validity of the model is proven by field test results and theoretical calculation results. By changing the cohesion, internal friction angle, elastic modulus of the embankment filler, and geogrid strength, the effects of various influencing factors on the pile–soil stress ratio, the load-sharing ratio of the soil arching effect, and the load-sharing ratio of the membrane effect was analyzed, and the sensitivity of each influencing factor was evaluated. Based on the response surface optimization test, the multiple regression equation of influencing factors and evaluation indicators was established. The interaction between the parameters was analyzed, and the optimal combination of parameters was solved. The results show the following: Increasing the cohesion, the internal friction angle, and the elastic modulus of the embankment filler can promote the soil arching effect to a certain extent. However, for reinforced embankments, a large cohesion, a large internal friction angle, and a high elastic modulus of an embankment will reduce the pile–soil differential settlement and the pile–soil stress ratio; an increase in geogrid strength has a certain promoting effect on the pile–soil stress ratio. When the geogrid strength reaches 120 kN/m, the pile–soil stress ratio tends to be stable; the tested regression model can accurately reflect the changes in the relationship between the influencing factors and the response values, and it fits the actual situation well. Numerical simulation results show that the optimized pile–soil stress ratio increases by 13.4%.