超固结粉质黏土静止土压力系数原位试验研究  

In-situ experimental study on coefficient of earth pressure at rest of overconsolidated silty clay

作　　者：陈树峰 孔令伟[2,3] 李焕焕 CHEN Shufeng;KONG Lingwei;LI Huanhuan(Shaanxi Key Laboratory of Safety and Durability of Concrete Structures,Xijing University,Xi’an 710123,China;State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]西京学院陕西省混凝土结构安全与耐久性重点实验室,陕西西安710123 [2]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [3]中国科学院大学,北京100049

出　　处：《水资源与水工程学报》2022年第6期182-188,共7页Journal of Water Resources and Water Engineering

基　　金：国家自然科学基金项目(12102367、41877281);陕西省自然科学基础研究计划项目(2021JQ-870);陕西省教育厅一般专项项目(21JK0961);西京学院高层次人才专项基金(XJ20B11)。

摘　　要：静止土压力系数K_(0)是岩土工程设计施工中的重要参数,其影响因素众多、变化特征复杂,合理地选取K_(0)测试分析方法是保证成果可靠性的关键。针对哈尔滨市超固结粉质黏土地层,开展了现场原位水平应力试验(KSB)、扁铲侧胀试验(DMT)与旁压试验(PMT)以及室内K_(0)固结试验,获得了超固结粉质黏土地层K_(0)分布特征,类比分析了KSB与其他测试方法的相关性、差异性和适用性。研究表明:KSB试验有效避免了常规“压入式”测试的经验性与扰动性问题,具有操作便捷、精度高等优点,测得场地超固结粉质黏土K_(0)值介于0.45~1.81之间,并沿深度方向逐渐降低;室内试验取样过程和PMT预钻成孔过程会引起原始水平应力释放,而再加载无法完全恢复其初始值,从而导致二者测试结果偏低;DMT的有效性取决于经验公式的选取,Marchetti公式高估了K_(0)值,而国内上海、苏州、杭州、西安等地区经验分析结果整体偏低,通过修正Marchetti公式,给出适宜于哈尔滨地区的超固结粉质黏土的K_(0)计算方法,可供勘察设计参考。The coefficient of earth pressure at rest(K_(0)),which is affected by a number of factors,is an important parameter for the design and construction of geotechnical engineering.Choosing appropriate method of test and analysis is the key to ensure the reliability of the test results.To investigate the K_(0) characteristics of a overconsolidated silty clay stratum in Harbin City,a series of in-situ tests,including K_(0) stepped blade test(KSB),dilatometer test(DMT),and pressuremeter test(PMT)together with laboratory K_(0) oedometer test were conducted and comparatively analyzed.The results showed that KSB avoided soil disturbance and empirical problems of conventional push-in tests,and possessed the virtues of simplicity,efficiency and high precision.The value of K_(0) obtained from KSB was in the range of 0.45-1.81,and presented a decreasing trend with the increase in depth.On the other hand,the K_(0) values from laboratory K_(0) oedometer test and PMT were severely underestimated due to the fact that the released initial lateral stress in the unloading process cannot fully recover during the reloading process.The reliability of DMT was strongly dependent on the empirical analysis formula selected.It is found that the K_(0) values of Harbin soil were markedly overpredicted by the conventional Marchetti formula;however,it underestimated the soils in Shanghai,Suzhou,Hangzhou and Xi’an.To estimate K_(0) of Harbin overconsolidated silty clay,a novel empirical formula was proposed based on the calibration of Marchetti formula,which can provide some reference for the related survey and design.

关 键 词：静止土压力系数 土体原位水平应力仪 粉质黏土 超固结土 原位试验 

分 类 号：TU411[建筑科学—岩土工程] TV32[建筑科学—土工工程]