基坑抗突涌计算方法的对比分析及应用探讨

DISCUSSION ON COMPARISON ANALYSIS AND APPLICATION OF CALCULATION METHODS TO ANTI-UPRUSH OF FOUNDATION PIT

在基坑抗突涌分析中,用上覆土层的重力来平衡水压力是一种常用的计算方法。但在上覆层整体性差和透性大的情况下,当上覆层最薄弱处的渗透力大于其有效重度时,上覆层就会发生失稳破坏,此时应采用上覆土层有效重度与渗透力平衡的计算方法来分析基坑底部的稳定性。这2种计算方法适用于不同情况,在使用中常易引起混淆。从其公式表达形式、机制、安全系数及适用范围等方面进行比较并分析其异同,得出选用计算方法的原则并应用于一深基坑的抗突涌分析。分析结果表明,该基坑的抗突涌分析计算中选用的方法是合理的。

The equilibrium between gravity of the upper impermeable stratum and water pressure is a common calculation method for anti-uprush of foundation pit.In case the effective unit weight of upper stratum is less than the seepage force,its low strength and high permeability will lead to the instability of the bottom of the foundation pit,and the calculation method equilibrating between effective unit weight and seepage force should be adopted in this case.The two kinds of the calculation methods are confusable in practical application.Similarities and differences between the methods,such as the expression,principium,safety coefficient and application,are analyzed,and the principles to choose the methods are discussed.The methods are also applied to a engineering project,and the achieved results indicate that the reasonable choice of calculation methods of anti-floating for foundation pit is important,and some valuable conclusions are drawn.