湖相沉积典型软土HSS模型参数取值研究

数值分析被广泛用于研究复杂环境下深基坑开挖变形，但本构模型及模型参数选择对计算结果合理性影响较大。比较分析多种本构模型的特点，硬化土小应变(HSS)本构模型能很好对软土场地基坑开挖引起的变形进行预测，但HSS模型参数多且取值困难。湖相沉积软土在昆明分布范围广，但针对此类土，特别是有机质含量及含水率较高的泥炭质土的HSS模型参数如何取值无相关研究。针对这些问题，对大量土工试验及取原状样进行室内试验资料进行分析，研究得到几个刚度参数间的经验取值关系，获得湖相沉积典型软土层的HSS模型参数。为检验HSS模型及相关参数取值的合理性，运用PLAXIS 2D数值分析软件，对软土场地的两个地铁基坑建立数值模型，计算在不同开挖工况下引起的基坑变形，并与实际变形监测值进行对比分析，两变形吻合较好，从而验证研究结果是合理可靠的，且研究结果对于深基坑支护设计、岩土工程研究及勘察等具有重要的参考价值。

Parameter value of HSS model for lacustrine sedimentary soft soil

Numerical analysis is widely used to study the excavation deformation of deep foundation pits in complex environment, but the constitutive model and the selection of model parameters have great influence on the rationality of calculation results. By comparing and analyzing the characteristics of various constitutive models, it is found that the constitutive model of hardening soil with small strain (HSS) can well predict the deformation caused by excavation of foundation pit in soft soil sites, but the parameters of HSS model are difficult to take values. The lacustrine sedimentary soft soil is widely distributed in Kunming area, but there are no relevant studies on how to select the parameters of HSS model for such soil, especially peaty soil with high organic matter content and water content. To solve these problems, data of many geotechnical tests and indoor tests of undisturbed samples were analyzed, and the relationship among empirical values of several stiffness parameters were obtained, then the HSS model parameters of typical lacustrine sedimentary soft soil were obtained. To examine the rationality of HSS model and related parameter values, numerical models for two subway foundation pits in soft soil site were established using the numerical analysis software PLAXIS 2D. The deformation of foundation pits under different excavation conditions were calculate and compared with the monitoring value of actual deformation. Results show that they are in good agreement, indicating that the calculated results are reasonable and reliable. The research results have important reference value for the support design of deep foundation pit and the geotechnical engineering research and investigation.