基于光纤光栅土体小应变刚度测试及小应变本构模型研究

项目名称： 基于光纤光栅土体小应变刚度测试及小应变本构模型研究

项目编号： No.51508215

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 建筑科学

项目作者： 徐东升

作者单位： 华中科技大学

项目金额： 20万元

中文摘要： 土体小应变刚度的非线性变化及本构模型的研究是认识土体在小应变状态下的力学机理，分析土与结构的相互作用，优化岩土结构变形控制的关键科学问题。本研究基于光纤光栅传感技术，开发并研制光纤光栅局部位移计，用于更精确测量土体的局部小变形并改装到三轴试验仪中，以典型黏土为研究对象，系统试验分析孔隙率、超固结度和有效应力对土体小应变刚度影响以及不同应力状态下土体小应变刚度的非线性变化，基于试验数据和理论研究，建立土体小应变刚度非线性变化的定量模型，结合修正的剑桥模型，建立考虑小应变状态下刚度非线性变化的本构模型，揭示岩土工程结构在施工或工后小应变状态下变形调控机理，阐明小应变刚度的非线性变化对变形控制的影响，为推动岩土结构工程的变形控制提供理论基础，为优化隧道、深基坑等岩土工程的变形控制提供科学依据。

中文关键词： 小应变；刚度；光纤光栅传感器；局部位移计；本构模型

英文摘要： The non-linear behavior of soil stiffness and the constitutive model at small strains are key scientific problems for understanding the soil mechanics at small strains, analyzing soil-structure interaction, and optimizing displacement controlled design for geotechnical structures. This project is based on the fiber optic sensing technology, development and design a new fiber optic sensors based local displacement transducer to measure soil small strain with high accuracy and resolution which will be modified into a triaxial apparatus. A series of tests will be conducted to analyze the effect of void ratio, over-consolidated ratio, and mean effective stress on the soil stiffness at small strains for a typical clay. Based on the test results and theory analysis, the non-linear relationship equation of soil stiffness at small strains will be derived. A new constitutive model with consideration of non-linear soil stiffness at small strains will be developed with combination of modified Cam-clay model. This new constitutive model can be used for displacement controlled design for geotechnical structures at small strain status during construction or in service. The effect of non-linear soil stiffness behavior on the displacement controlled design will be elaborated. The outcomes of this project can provide theoretical and scientific basis for displacement controlled design and optimized design of tunnels, deep excavations and other geotechnical projects.

英文关键词： small strain;stiffness;fiber optic sensor;local displacement transducer;constitutive model