承压水地层基坑坑底压拉突涌评价与物理试验

基于基坑坑底隔水层在承压水作用下承受过量弯矩发生压剪破坏或拉裂破坏假设,分别推导出了考虑土体抗剪强度和抗拉强度的基坑突涌判别公式。与现有的基坑突涌判据认为基底隔水层边缘最先发生破坏的结论不同,本判据认为基底隔水层中间部位最先发生破坏。并通过简易的基坑突涌物理试验,试探性验证了基坑基底中间部位最先发生破坏的现象。依托实例,基底隔水层临界厚度计算结果表明,除与压力平衡法的计算结果差别较大外,与其他基坑突涌评价方法的计算结果均较为接近。仅就算例和模型试验来看,利用该判据理论进行基坑突涌分析比目前规范规定的分析方法更接近实际,但需经大量工程实践的检验。

Compression-tension Failure Evaluation and Physical Experiment for Confined Water Foundation Pit Inrushing

According to the assumption that the foundation pit aquifuge would cause compression-shear or tensile failure under excessive bending moment produced by confined water, discrimination formulae for foundation pit inrushing were derived, taking both shear and tensile strength of soil mass into account. Different from current foundation pit inrushing criterions, the new criterion assumes that the central section of foundation pit aquifuge fails first while other criterions assume that the pit edge does. A simple foundation pit inrushing physical experiment was carried out to verify the phenomenon that the central section fails the first. Relying on an example, the calculation results of critical thickness for foundation pit aquifuge indicated that the result of discrimination formulae proposed in the paper was similar to those of other common methods except that of the pressure balance method. Just for examples and experiment, the new foundation pit inrushing criterion is closer to the reality than that the specification recommended. More experiences in engineering practice are needed.