软土基坑支护深度滑移线解研究

基于滑移场理论,分析了基坑底部被动滑移区BDE、过渡区BCD和主动滑移区ABC的区域应力状态,推算出基坑底部在假设支护深度为t时的土体极限承载力滑移线解,并以此反算出满足软土基坑抗隆起稳定安全性要求的支护深度。此外,还可求出软土基坑抗隆起稳定性安全系数以应用于抗隆起稳定性验算,并且在均质土前提下,经过简单换算得到与普朗德尔极限平衡理论公式的基坑抗隆起稳定性安全系数k相同的结果。结合工程实例验证了软土基坑支护深度滑移线解和软土基坑抗隆起稳定性安全系数的合理性。

Research on Slip-Line Solution to Supporting Depth of Soft Soil Excavations

Based on slip field theory, analyses the stress state of passive slip zone BDE, transition zone BCD and active slip zone ABC at the excavation bottom, and infers the slip-line solution to soil ultimate bearing capacity of the excavation bottom at the assumed supporting depths t, and calculates the supporting depth in accordance with the soft soil excavation against heave stability safety requirements. Moreover determines the safety coefficient against heave stability for anti heave stability checking, and under homogeneous soil conditions, through the simple conversion obtains the same result with the safety coefficient k of excavation against heave stability by Prandtl limit equilibrium theory. Combined with engineering examples, slip-line solution of supporting depth in soft soil excavations and soft soil foundation heave stability safety coefficient are verified to be reasonable.