182 / 2023-08-31 21:50:28

Feasibility of the Synergy Effect of Pile Groups Foundation with Base across Post-mining area: A case study

post-mining area;,Pile group foundation;,critical depth,mining subsidence

Abstract: It is urgent to evaluate the feasibility of the expressway’s pile group foundation with the base to ensure construction safety in the post-mining area. In this paper, Jining Expressway Project in Shandong Province, eastern China as a case study, the specific conclusions were as follows: (1) The soil reaction coefficient m method is used to analyze the horizontal displacement of pile foundation, pile bending moment, shear force and soil stress distribution around pile under horizontal deformation. (2) Midas GTS NX finite element simulation method was used to establish a numerical model of the pile group foundation and finite element simulation was carried out on the pile group composite foundation above the goaf under different vertical stress loading and different horizontal displacement loading conditions. The distribution of axial force, displacement, and bending moment of the pile body was analyzed. The disturbance range of additional stress and the depth of load safety influence of pile group foundation is obtained under different criteria and different upper loading conditions. The smaller the discriminant coefficient of the pile group foundation load is, the greater the depth of load influence is. When the discriminant coefficients are the same, the greater the building load is, the greater the load influence depth is. The numerical simulation results show that the inner boundary settlement of the goaf is large and the non-uniform settlement is obvious, so it is not suitable for the construction site. The middle part of the goaf has small settlement deformation and no obvious uneven settlement so it can be used as a construction site. (3) The disturbance depth of additional load under the loading condition of 2 ~5 times of the superstructure is analyzed, and the influence depth of 5 times of the load HDz-5P is used as a reference for the influence depth of additional stress of pile group foundation. (4) A quantitative method is proposed for the stability of pile group foundations. A logistic regression model with the stability of the pile group foundation as an independent variable is constructed, taking the influence degree of the caving site on pile group foundation I and the stability of the goaf site itself as independent variables. The results have theoretical significance and practical value for the feasibility analysis of post-mining area construction under similar engineering geological conditions.