摘要
在我国沿海地区,过量抽取利用地下水引发了明显的地面沉降,限制开采量、人工回灌地下水对减轻地面沉降具有显著效果。开采与回灌地下水促成了地下水位的大幅波动,使得沿海地区广泛分布的软土层发生了明显的沉降与回弹变形。为了研究软土在水位波动作用下的变形和强度特性,利用沉降柱试验装置模拟地下水位波动,对不同水位波动次数作用后的软土试样进行了高压固结试验、直剪试验和三轴试验,研究了水位波动次数对软土变形性状的影响,给出了用初始强度指标和含水量表示的、不同水位波动次数作用后的软土残余强度表达式。试验结果表明:随着水位波动次数的增加,软土的变形特性增强而强度特性降低,黏聚力和内摩擦角随波动次数的增加呈近似线性降低;相同水位波动次数下软土试样的强度指标随含水量的增加呈明显下降趋势。研究成果对于探索城市地下水位波动对地面沉降和承载力变化的作用机理,提高科学决策水平及减轻环境地质灾害有着重要实际意义和应用价值。
The excessive extraction of groundwater caused obvious ground subsidence in the southeastern coastal areas of China.Exploitation restriction and artificial recharge of groundwater have significant effects on mitigating the ground subsidence.These measures lead to drastic fluctuations of water level and significant settlement and rebound deformation of the widespread soft soil in the coastal areas.In order to investigate the deformation and strength of soft soil under water level fluctuation,by using the cylinder model experiment device to simulate water level fluctuation,we conducted high-pressure consolidation test,direct shear test,and triaxial test on the soft soil after different times of water level fluctuation.Based on the analysis of the influence degree of water level fluctuation on the deformation behavior and strength characteristics of soft soil,we presented a relational expression of the residual strength of soft soil after different times of water level fluctuation using initial strength and water content.The test results showed that as the frequency of water level fluctuation increased,the deformation properties of the soft soil were enhanced and the strength was reduced.The cohesion and internal friction angle decreased linearly with the increase of water level fluctuations.The strength index of the soft soil under the same times of water level fluctuation declined significantly with the increase of water content.The results have important practical significance and application value on exploring the action mechanism of water level fluctuation on ground subsidence and bearing capacity changes,improving the level of scientific decision-making,and mitigating environmental geological disasters in coastal cities.
作者
陈能远
孟庆山
CHEN Nengyuan;MENG Qingshan(School of Highway,Chang′an University,Xi′an 710054,China;Electric Comprehensive Survey Institute of Information Industry Department,Shaanxi Province Soil Engineering Technology Research Center,Xi′an 710054,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China)
出处
《南水北调与水利科技》
CSCD
北大核心
2018年第5期165-170,共6页
South-to-North Water Transfers and Water Science & Technology
基金
国家自然科学基金项目(40902092)~~
关键词
软土
水位波动
强度指标
含水量
衰减系数
soft soil
water level fluctuation
strength index
water content
attenuation coefficient
