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Abstract：
Based on the effective stress principle, indoor model tests were conducted in this study to calculate the buoyancy of an underground structure and determine the law of pore water pressure conduction in silty clay strata. A comprehensive underground structure-water-soil interaction test system was established with four-in-one features: Elimination of lateral friction, controllable water head, circulating water supply and drainage, and simulation of groundwater flow. Four- and seven-gradient buoyancy continuous monitoring tests were completed using fine sand and silty clay, respectively, to verify the reliability and accuracy of the test system. The hydrostatic pressure and seepage-hydrostatic process of the silty clay strata were simulated separately to investigate the buoyancy of the underground structure of the strata, the buoyancy reduction coefficient, and the pore water pressure conduction law. The results show the reliability and accuracy of the comprehensive test system for underground structure-water-soil interaction. The concept of \"buoyancy starting intercept\" is proposed based on this system, where the underground water level value should be the head of water supply minus the \"buoyancy starting intercept\" when calculating buoyancy in weak permeable layers. Under hydrostatic action, the groundwater is phreatic, deeper burial depths show greater magnitude of this discount. When the groundwater is confined, the water head reduction coefficient increases with increase in the burial depth or hydraulic gradient. Buoyancy calculations of an underground structure within the range of confined water should not be reduced in this case. Whether in a seepage or hydrostatic state, the pore water pressure in the silty clay layer is below the theoretical value. The results of this work may provide a theoretical basis for further analysis of the pore water pressure conduction law and buoyancy reduction mechanism of clay soils. We also may provide a theoretical reference for the development of innovative underground structure-water-soil interaction comprehensive test systems.
摘要：
基于有效应力原理,本研究进行了室内模型试验，计算了地下结构的浮力，确定了粉质粘土地层中孔隙水压力传导规律。建立了具有四合一特征的综合地下结构-水-土相互作用测试系统：消除横向摩擦，可控水头,循环水给排水,和模拟地下水流。采用细砂和粉质粘土完成了四、七梯度浮力连续监测试验,分别,验证了测试系统的可靠性和准确性。分别模拟了粉质粘土地层的静水压力和渗流静水压力过程，以研究地层地下结构的浮力。浮力降低系数，和孔隙水压力传导规律。结果表明，该地下结构-水-土相互作用综合测试系统的可靠性和准确性。基于该系统提出了“浮力起始截距”的概念，计算弱透水层浮力时，地下水位值应为供水水头减去“浮力起始截距”。在静水压作用下，地下水是潜水的，更深的埋葬深度表明这种折扣的幅度更大。当地下水被限制时，水头降低系数随埋深或水力坡度的增加而增加。在这种情况下，不应减少在承压水范围内的地下结构的浮力计算。无论是在渗流还是静水状态，粉质粘土层中的孔隙水压力低于理论值。研究结果可为进一步分析黏土的孔隙水压力传导规律和降浮力机理提供理论依据。为开发创新型地下结构-水土相互作用综合试验系统提供理论参考。
