SOIL'S SMALL STRAIN PARAMETERS SENSITIVITY ANALYSIS OF METRO DEEP FOUNDATION PIT EXCAVATION EFFECT IN XIAMEN AREA

Hardening soil small model (HSS) can consider not only soil shear and compression hardening, but also account for shear modulus attenuating in tiny strain range. Therefore, it has a good application for numerical analysis of excavations. To study the sensitivity of HSS model's stiffness parameters E₅₀^ref, G₀^ref and γ_0.7 on the excavation's numerical analysis results in Xiamen area, based on sensitivity analysis theory and orthogonal experiment theory, representative residual sandy sticky clay, silty clay and mucky soil are chosen to serve as research objects, and take surface subsidence value of excavation and enclosure wall's maximum moment value as a control index. Single control on soil layer's parameters sensitivity study is applied respectively. The result shows that to calculate surface subsidence and enclosure wall's moment accurately in excavation numerical analysis. Firstly, control the value of soil's G₀^ref; secondly, E₅₀^ref impacts less than γ_0.7; with the deepening of the excavation depth, the impact of G₀^ref for surface subsidence becomes less, while E₅₀^ref and γ_0.7 impacts more; E₅₀^ref impacts less on enclosure wall's moment with the deepening of the excavation, while G₀^ref and γ_0.7 tend to impact more, especially for G₀^ref. The results show that small strain behavior of soil is of great importance to excavation construction and deserves more attention in relevant design and construction. The analysis results could provide references for the acquirement of more reasonable stratum deformation and structure inner force in deep excavation finite element analysis.