论文部分内容阅读
已有研究表明,天然黏土的强度表现出明显的各向异性,但其规律未能经过严格的试验验证。基于空心圆柱仪(HCA)的杭州原状软黏土试验结果,对Casagrande法进行修正,提出大主应力方向为任意方向剪切时土体的强度公式。假定基坑开挖引起的土体滑动破坏模式为Prandtl模式,利用上述强度公式,得到基坑抗隆起稳定的塑性上限解。结合算例,讨论了土体强度各向异性比、挡墙入土深度比、墙底下卧硬土层深度、挡墙粗糙度等因素对基坑坑底抗隆起稳定的影响。采用该方法分析杭州某失稳基坑实例,通过与已有方法的结果对比,验证了所提方法的合理性。研究表明,不考虑土体强度各向异性和基于Casagrande各向异性公式的抗隆起分析都将高估杭州软黏土基坑的抗隆起稳定性。
Studies have shown that the strength of natural clay showed significant anisotropy, but its laws failed to undergo rigorous testing. The modified Casagrande method was modified based on the test results of Hangzhou intact soft clay with Hollow Cylinder (HCA), and the strength formula of the soil under shearing in arbitrary direction was proposed. Assuming that the soil sliding failure mode caused by excavation is Prandtl mode, the plastic upper limit solution to the anti-swelling of the foundation pit is obtained by using the above-mentioned strength formula. The effects of anisotropy ratio of soil mass, depth ratio of retaining wall to soil, depth of hard soil lying on the bottom of the wall and roughness of retaining wall on the anti-swelling of pit bottom are discussed. By using this method, an example of a destabilization foundation pit in Hangzhou is analyzed. Compared with the results of the existing methods, the rationality of the proposed method is verified. The research shows that the anti-uplift analysis based on the anisotropy of soil mass and the Casagrande anisotropy formula will overestimate the anti-swelling stability of Hangzhou soft clay foundation pit.