Mechanical Performance of Composite Retaining and Protection Structure for Super Large and Deep Foundation Excavations

Abstract

The reliable retaining methods and a good stress system are the key to the success of super large and deep excavation engineering. In this paper, the deepest foundation pit in Hainan province is taken as an example. The method of mutual verification between in-situ monitoring and numerical simulation is adopted. The mechanical performance of composite retaining structure composed of reinforced concrete cast-in-situ soldier pile wall, diaphragm wall and prestressed anchor cable are studied. The interaction between the reinforced concrete cast-in-situ pile retaining structure at the upper part and the diaphragm wall retaining structure at the lower part is revealed, and the variation of internal forces of the diaphragm wall retaining structure in the time and space is demonstrated. And then the influence of insertion ratio and rigidity on the mechanical properties of diaphragm wall is discussed. Research shows, the range of interaction between the upper and lower retaining structures is limited. During the excavation process, the maximum bending moment of the diaphragm wall is always near the excavation surface, and the curvature of the bending moment curve decreases gradually with the increase of excavation depth and axial tension of anchor. When the insertion ratio of diaphragm wall increases, the maximum bending moment moves upward. With the rigidity of the diaphragm wall increases moderately, the bending moment of the retaining structure increases, but the lateral displacement decreases. The research results can provide theoretical basis and practical experience for the composite retaining structure design of super large and deep foundation excavations.

Deformation Characteristics of the Foundation Pit of the Underpass Viaduct and Grey Relational Analysis of the Maximum Horizontal Deflection of the Retaining Wall

“…In addition, the FEM can be used to develop three-dimensional fluid-solid coupling models to investigate complex foundation pit seepage problems and predict the influence of seepage and dewatering on ground settlement and the surrounding environment [18][19][20]. However, due to the complexity of strata, it is often necessary to compare field monitoring data with numerical results to correct the finite element model and verify the reliability of the model simulation [21][22][23]. Reference [24] proposed a simplified semiempirical model and used it to predict the maximum wall deflection, maximum surface settlement, and surface settlement profile caused by excavation in soft clay.…”

Determination of Embedded Depth of Soldier Piles in Pile-Anchor Supporting System in Granite Residual Soil Area

“…Hyodo et al [13] performed a three-dimensional analysis of the inadequate length of the soldier piles and obtained the relationship between load and settlement for the inadequate embedded depth of the soldier piles. Cui and Li [14] discussed the effects of the soldier pile insertion ratio and stiffness on the mechanical properties of the diaphragm wall using the method of field monitoring and numerical simulation correlation verification by using the deepest foundation pit project in Hainan Province as an example. The maximum bending moment of the row pile rises as the insertion ratio increases.…”