高温冻土固结试验研究与理论分析  

Theoretical Analysis and Experimental Study on Consolidation Test for Warm Frozen Soil

作　　者：刘世伟 吕生玺 张建明 张虎 明锋 LIU Shiwei;LYU Shengxi;ZHANG Jianming;ZHANG Hu;MING Feng(Gansu Research Institute of Survey and Design of Water Conservancy&Hydropower Co.,Ltd.,Lanzhou 730000,China;State Key Laboratory of Frozen Soil Engineering,Northwest Institute of Ecology and Environmental Resources,Chinese Academy of Sciences,Lanzhou 730000,China)

机构地区：[1]甘肃省水利水电勘测设计研究院有限责任公司,甘肃兰州730000 [2]中国科学院西北生态环境资源研究院冻土工程国家重点实验室,甘肃兰州730000

出　　处：《人民黄河》2020年第8期136-141,145,共7页Yellow River

基　　金：国家自然科学基金青年科学基金资助项目(41471062,41401087);冻土工程国家重点实验室自主课题(SKLFSE-ZT-35);甘肃省重点研发计划项目(17YF1WA155)。

摘　　要：高温冻土在加载或升温条件下具有较大变形,为充分认识其变形特性及机理,开展一系列室内固结试验,研究了不同含水量(40%、80%、120%)、不同温度(-0.3、-0.5、-0.7、-1.0、-1.5℃)的冻土在分级加载(0.1、0.2、0.3、0.4、0.5 MPa)条件下的压缩变形。采用3种整理压缩试验数据的方法(e—p、e—lg p及ε—p曲线)获取了高温冻土不同温度下的压缩模量、压缩指数及割线模量等压缩性指标。结果显示:压缩模量Es1-2处于高压缩性模量区间,指数函数可很好地描述压缩指数随温度的变化规律,ε—p曲线基本服从双曲线模型。固结系数采用Taylor提出的时间平方根法计算,发现高温冻土固结系数与超软土具有相同的量级,且其固结应力的变化规律与软土相似。为了模拟高温冻土固结试验,基于饱和冻土的三相关系、质量守恒及有效应力原理,推导了高温冻土的太沙基一维固结方程,获得了固结系数理论表达式。通过对比固结系数理论值与试验值的量级及随温度的变化规律,发现传统的太沙基固结理论不适用于解释高温冻土变形机理。Warm frozen soil will generate remarkable deformation under loading or temperature rise.In order to fully recognize the deformation properties and mechanism of warm frozen soil,a series of laboratory tests were conducted to study the consolidation deformation for frozen soil with different water contents of 40%,80%and 120%at different temperatures(-0.3,-0.5,-0.7,-1.0 and-1.5℃)under stage continuous loading conditions(0.1,0.2,0.3,0.4 and 0.5 MPa).The compression parameters consisting of compressibility modulus and compressibility index and secant modulus were obtained on the basis of compression tests.The results show that the values of compressibility modulus Es1-2 are located in high compressibility region,exponential function can perfectly describe the relationship between compressibility index and temperature,εp curves are basically in accordance with hyperbolic model.Consolidation coefficient obtained from tests can be evaluated by adopting Taylor’s t method.The test results indicate that the consolidation coefficient of warm frozen soil has the magnitude of order just the same as that of ultrasoft soil,the relationship between consolidation coefficient and consolidation stress obeys the same regulation law as a soft soil does.In order to simulate the process of consolidation test,onedimension Terzaghi consolidation differential equation for warm frozen soil was proposed on account of the three phase composition and mass conservation and principle of effective stress.A theoretical expression of consolidation coefficient was derived spontaneously.We compared the magnitude of consolidation coefficient between theoretical values and experimental values.Meanwhile,the change regulation between consolidation coefficient and temperature had been discussed.It is concluded that the deformation mechanism of warm frozen soil cannot be explained by Terzaghi consolidation theory.

关 键 词：高温冻土 固结试验 割线模量法 固结系数 变形机理 

分 类 号：P642.14[天文地球—工程地质学] TV223.2[天文地球—地质矿产勘探]