宁波海相软弱土层人工冻土强度特性试验  

Experimental study on strength properties of artificial frozen soil in marine soft soil area of Ningbo City,China

作　　者：江汪洋 杨平[1] 陈斌[2] 何文龙[1] 

机构地区：[1]南京林业大学土木工程学院,南京210037 [2]宁波市轨道交通工程建设指挥部,浙江宁波315010

出　　处：《林业工程学报》2017年第5期126-131,共6页Journal of Forestry Engineering

基　　金：国家自然科学基金(51478226);江苏高校优势学科建设工程资助项目(PAPD);宁波轨道交通有限公司科研资助项目

摘　　要：人工冻土强度特性具有区域性,以宁波轨道交通2号线3种海相典型土质(淤泥质黏土、粉质黏土和粉土)开展冻土单轴抗压和三轴剪切试验研究。结果表明:3种土质在不同温度下试样均为腰鼓形塑性破坏,应力-应变曲线基本呈应变硬化型,但随温度降低有向应变软化转变的趋势;单轴抗压强度和弹性模量均随温度降低而近似线性增大;重塑粉质黏土抗压强度和弹性模量均与应变速率呈幂函数关系增长;各土质最大轴向偏应力随围压的增大而增大,且具有线性关系,-10℃抗剪强度指标(c、φ)均得到大幅提高,黏聚力提高1.23~1.76MPa;宁波地区典型粉质黏土与其他地区类似地层相比,单轴抗压和抗剪强度均较低,而弹性模量偏中等,与上海地区同类土质接近。The strength of artificial frozen soil has regional characteristics. In this study, the uniaxial compressive strength test and triaxial shear strength test of frozen soils were carried out on three types of typical marine soils （ muddy clay, silty clay and silt） in No. 2 Line of Ningbo Rail Transit. The results showed that three types of soil samples at different temperatures were all drum-shaped plastic failure, and the stress-strain curves substantially assumed the strain hardening form, but the strain tended to soften with the decrease of the temperature. The uniaxial compressive strength and elastic modulus of each soil were increased linearly with the decreasing temperature, and the uniaxial compressive strength of silty clay was most affected by temperature （ the temperature reduced by 1℃, and the strength increased by 0.3 MPa）. At the strain rate of 10%/min, the uniaxial compressive strength of remolded silty clay was a- bout 8% higher than that of the undisturbed silty clay, and the elastic modulus was about 7% lower than that of the undisturbed silty clay. The compressive strength and elastic modulus of the remolded silty clay all increased with the power function of the strain rate. The maximal axial deviator stresses of the three soils increased linearly with the increase of confining pressure, and the order of maximum axial deviator stresses of different soils was silt 〉 silty clay 〉 muddy clay. The shear strength index （c, φ） at -10℃ was significantly improved compared with the normal tempera- ture in particular, and the cohesion increased by nearly 1.23-1.76 MPa. The typical silty clay in Ningbo was com- pared with those of similar stratum in other areas （ Nanjing City and Shanghai City ）. The uniaxial compressive strength and shear strength were relatively low, while the elastic modulus was moderate, which was close to those of Shanghai.

关 键 词：宁波海相软弱地层 人工冻土 单轴抗压强度 三轴剪切强度 应变速率 

分 类 号：TU445[建筑科学—岩土工程]