Effect of Bio-Cementation on Drained Instability of Poorly Graded Sand with Sub-Angular Particle Shapes
Effect of Bio-Cementation on Drained Instability of Poorly Graded Sand with Sub-Angular Particle Shapes
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生物胶结对次角粒状不良级配砂排水失稳的影响
DOI：
10.1061/9780784484661.058
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Evans, T. M.
中科院分区：
文献类型：
--
作者：
Yazdani, E.;Montoya, B.;Evans, T. M.
文献中已经报道了在低于会导致传统破坏的应力水平的排水条件下经历不稳定行为的斜坡的案例研究。这里，不稳定行为是指由于应力条件的微小变化而导致的土壤突然塌陷。这种响应被称为排水（扩散）不稳定性，与广泛认可的不排水条件下砂的静态液化失效机制有很大不同。微生物诱导碳酸盐沉淀（MICP）作为一种土壤改良技术，对土壤的抗剪强度具有良好的效果，并有可能用于减少粒状边坡的不稳定。为了更好地理解这种塌陷机制，对经过处理和未经处理的样本进行了一系列单调三轴试验，以评估生物胶结改进对排水条件下不稳定性的影响。实验分两个阶段进行。加载的第一阶段使用了不同的应力条件，包括应力引起的各向异性。之后，在试验的第二阶段使用恒定剪切排水（CSD）应力路径，通过以恒定速率降低围压来不断降低平均有效应力，直到达到不稳定。本研究调查了经过处理和未经处理的样品的不稳定性的发生。
Case studies of slopes experiencing unstable behavior under drained conditions below the stress level that would cause a traditional failure have been reported in the literature. Here, unstable behavior refers to a sudden collapse of soil resulting from a small change in stress conditions. This response, which is known as drained (diffuse) instability, is quite different from the widely recognized static liquefaction mechanism of failure for sand under undrained conditions. Microbially induced carbonate precipitation (MICP) as a soil improvement technique has a promising effect on the shear strength of soils and has potential to be used to reduce the potential of instability in granular slopes. To provide a better understanding of this collapse mechanism, a series of monotonic triaxial tests on treated and untreated specimens have been carried out to evaluate the effect of bio-cementation improvement on the instability under drained conditions. The experiments were conducted in two stages. Different stress conditions, including stress-induced anisotropy, were used for the first stage of loading. After that, a constant shear-drained (CSD) stress path was used in the second stage of the test as the mean effective stress was continuously reduced by decreasing confining pressure with a constant rate until instability was reached. The onset of instability in treated and untreated samples was investigated in this study.