Effect of spatial variation of strength and modulus on the lateral compression response of cement-admixed clay slab
Effect of spatial variation of strength and modulus on the lateral compression response of cement-admixed clay slab
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DOI：
10.1680/geot.14.p.254
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发表时间：
2015-01-01
期刊：
影响因子：
5.8
通讯作者：
Yi, J. -T.
中科院分区：
文献类型：
--
作者：
Liu, Y.;Lee, F. -H.;Yi, J. -T.
在深基坑工程中，通常采用深层搅拌法或高压喷射注浆法在软土中形成水泥土搅拌桩加固土层。这些土层的目的是抵抗挡土墙移动产生的侧向压力。众所周知，水泥土在强度上具有高度的不均匀性。在本文中，强度和杨氏模量的不均匀性进行了研究，使用随机有限元分析，考虑三个来源的变化：即，确定性的径向趋势强度和杨氏模量;随机波动分量，由于不均匀的混合;和定位所产生的错误从偏离垂直的搅拌轴。结果表明，定位误差有最大的影响，作为一个整体的板的强度，而径向趋势具有最小的影响，当归一化的体积平均强度。根据所获得的结果，提出的方法，允许等效均匀质量的强度和模量的改进板被确定为一个选定的百分位数的刚度或可靠性指标，它可以用于确定性有限元分析。
In deep excavation construction, improved soil layers consisting of overlapping cement-admixed columns formed by deep mixing method or jet grouting are often used to stabilise an excavation in soft soils. The purpose of such soil layers is to resist lateral compression generated by movement of the retaining wall. Cement-admixed soils are well known to have high heterogeneity in strength. In this paper, the heterogeneity in strength and Young's modulus are studied using random finite-element analyses, considering three sources of variation: namely, a deterministic radial trend in strength and Young's modulus; a stochastic fluctuation component due to non-uniform mixing; and positioning errors arising from off-verticality of the mixing shafts. The results show that positioning errors have the largest effect on the strength of the slab as a whole, whereas the radial trend has the smallest effect, when normalised by the volume-average strength. Based on the results obtained, methods are proposed which allow equivalent homogeneous mass strength and modulus of the improved slab to be determined for a chosen percentile of exceedance or reliability index, which can be used in deterministic finite-element analyses.