考虑主应力轴偏转效应的天然沉积软黏土蠕变特性研究

The disaster of clay slope and foundation due to creep always occurs with rotations of principal stresses imposed in soils. Current studies on disaster analyzing methods show a lack of consideration for the effect of principal stress rotation on the creep behavior of soft clay in the world. The proposed project aims to build up a predictive method for long-term deformation and progressive failure of soft clay under stresses with different degrees of principal stress rotation. Intact and reconstituted samples of natural deposited soft clay will be adopted for the study. Torsional shear creep tests in Hollow Cylinder Apparatus, theoretical analyses and numerical simulations will be combined to conduct the study of creep behavior under different degrees of principal stress rotation: 1) to investigate the influence of principal stress rotation on the non-coaxial creep and creep rate; 2) to establish the relationship between the non-coaxial creep and the destructuration of clay; 3) to propose the consolidation coupled non-coaxial creep model and establish a prediction method for the creep disaster. The results of the project will break through the current long-term stability analysis of geotechnical engineering structures, which cannot take into account the principal stress rotation effect on the creep behavior. The results can also provide the theoretical bases for elucidating the mechanism of long-term deformation and progressive failure of natural soft clay, provide practical and reliable computing tools for practical engineering, and provide scientific basis and theoretical support for the disaster prevention of clay slope and foundation under complex stress states.

针对软黏土坡体和地基长期变形和渐进破坏等蠕变灾害大多发生在主应力轴偏转应力状态下的客观实际，及目前国内外尚无考虑主应力轴偏转影响的蠕变灾害分析方法的研究现状，本项目以建立软黏土坡体和地基长期变形和渐进破坏预测方法为目标，以天然沉积软黏土原状土和重塑土为研究对象，采用空心圆柱扭剪试验、理论分析及数值模拟相结合的方法，开展不同主应力轴偏转下土体的蠕变特性研究：1）探索主应力轴偏转对非共轴蠕变及其速率的影响规律；2）阐明非共轴蠕变与土体结构状态破坏的相互作用机制；3）提出非共轴蠕变模型并建立蠕变灾害预测分析方法。本研究可解决现有软黏土坡体和地基稳定分析方法尚无法考虑软黏土蠕变特性及其主应力轴偏转效应的缺陷，为阐明天然沉积软黏土长期变形及渐进破坏机制奠定理论基础，并为实际工程提供实用、可靠的计算理论，为复杂应力状态下软黏土坡体和地基的蠕变灾害防治提供科学依据与理论支撑。

本项目以天然软土为研究对象，针对软土流变特性尤其是主应力轴偏转造成的各向异性流变特性，在项目执行期内（1年）开展了试验和理论的初步探讨，提出了主应力轴偏转对蠕变及其速率和应力剪胀关系的影响规律，建立了各向异性流变模型,为解决现有软黏土坡体和地基长期变形和渐进破坏分析中尚无法考虑各向异性蠕变特性奠定了基础。.项目执行期内，共申请相关专利4项，软件著作权1项，获教育部科学技术进步奖二等奖(排名第11)1项、浙江省科学技术进步奖二等奖(排名第2)1项，相关内容发布SCI期刊论文3篇、EI期刊论文4篇，培养硕士研究生2名、博士研究生2名。