合肥膨胀土吸湿膨胀特性数值模拟研究  

Numerical Simulation of Water-increased Expansion of Expansive Soil in Hefei

作　　者：范从友 

机构地区：[1]中铁二十四局集团安徽工程有限公司,合肥230011

出　　处：《土工基础》2017年第6期753-757,共5页Soil Engineering and Foundation

摘　　要：膨胀土地层含水量变化会引起膨胀应力场,继而对隧道、基坑支护结构产生影响。基于温度场与湿度场相关理论表达式的相似性分析,明确了采用吸热膨胀模拟吸湿膨胀的关键是通过对土工试验数据进行反演确定热分析所需的热膨胀系数α和导热系数λ。以合肥地区三类典型膨胀土样为例,开展室内膨胀力试验和表面浸润试验,分别获得三类膨胀土样的膨胀力﹣初始含水量关系曲线和含水量﹣浸润时间关系曲线。采用PLAXIS程序构建与土工试验对应的轴对称数值模型,通过热﹣力耦合模拟一系列膨胀力试验和表面浸润试验,最终反演出与吸湿膨胀过程相对应的热膨胀系数和导热系数值。结果表明,通过本文方法可以方便、准确地反演出吸湿(吸热)膨胀计算关键参数,可用于膨胀土地区隧道和基坑工程在土体吸湿条件下的计算分析。The swelling stress field caused by the change in the moisture content in expansive soils will lead to an adverse effect on the behavior of retaining structures of tunnels and deep excavations.Based on the similarity of relevant theoretical expressions of thermal field and moisture field,the water absorbance induced expansion can be simulated by the temperature induced expansion in which the thermal expansion coefficient,α,and the thermal conductivity coefficient,λ,need to be firstly back-analyzed.A series of swelling force tests and surface wetting tests were conducted on the expansive soil samples taken from three typical strata in Hefei.The relationship between the swelling force and the initial moisture content and the empirical relations between the moisture content and the infiltrating time were established.Then the axisymmetric numerical model was established to simulate the swelling force test and the surface wetting test through thermal-mechanical coupling analysis.Both the numerical simulations and the laboratory tests resulted in consistent results and the thermal expansion coefficient and thermal conductivity coefficient could be statistically back analyzed.The back-analyzed parameters could then be used in further analysis of tunneling and excavation engineering in expansive soils considering water-absorbance process.

关 键 词：膨胀土 热-力耦合 膨胀力 热膨胀系数 

分 类 号：TU442[建筑科学—岩土工程]