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采用统一强度理论推导出极限状态条件下考虑渗流效应的土压力计算公式,引入了中主应力对土压力的影响参数b,提出了与各土层物理力学参数相关的系数ξ,研究了某盾构始发井围护工程土压力的分布特征.结果表明:影响参数b不同,中主应力对土压力的计算结果影响程度不同,b值愈大,主动土压力pa愈小,引起土压力值的最大差异可达18%;渗流效应对地下连续墙侧的水土压力影响较大,与未考虑渗流的计算结果相比,最大差异可达20%;系数ξ与土层的水力梯度相关,其计算多层土时的水压力分布呈非线性,得到的总压力值更接近实际情况.
Based on the unified strength theory, the earth pressure calculation formula considering the seepage effect under the limit state is deduced. The influence parameter of the middle principal stress on the earth pressure is introduced. The coefficient ξ related to the physical and mechanical parameters of each soil layer is proposed. The results show that the influence parameter b is different, the influence degree of the middle principal stress on the earth pressure calculation is different, the bigger the b value is, the smaller the active earth pressure pa is, which leads to the earth pressure value The maximum difference can reach 18%. The seepage effect has a great influence on the water and soil pressure on the diaphragm wall. The maximum difference can reach 20% compared with the result without considering the seepage flow. The coefficient ξ is related to the hydraulic gradient of the soil layer. When calculating the multi-layered soil water pressure distribution is nonlinear, the total pressure value obtained is closer to the actual situation.