Responses of calcareous sand foundations to variations of groundwater table and applied loads  

作　　者：Dingfeng Cao Sanjay Kumar Shukla Linqing Yang Chengchao Guo Jinghong Wu Fuming Wang 

机构地区：[1]School of Civil Engineering,Sun Yat-sen University,Guangzhou,510275,China [2]Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai,519082,China [3]Discipline of Civil and Environmental Engineering,School of Engineering,Edith Cowan University,Perth,6027,Australia [4]School of Architectural Engineering,Guangzhou Institute of Science and Technology,Guangzhou,510540,China [5]School of Civil Engineering,Suzhou University of Science and Technology,Suzhou,215011,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2022年第4期1266-1279,共14页岩石力学与岩土工程学报（英文版）

基　　金：support provided by the National Natural Science Foundation of China(Grant No.41907244);China Postdoctoral Science Foundation(Grant No.2019M653180);the Project of the Key Laboratory of Soft Soil and Environmental Geotechnical Ministry of Education(Grant No.2019P05)is gratefully acknowledged.

摘　　要：The long-term settlement of calcareous sand foundations caused by daily periodic fluctuations has become a significant geological hazard,but effective monitoring tools to capture the deformation profiles are still rarely reported.In this study,a laboratory model test and an in situ monitoring test were conducted.An optical frequency domain reflectometer(OFDR)with high spatial resolution(1 mm)and high accuracy(10-6)was used to record the soil strain responses to groundwater table and varied loads.The results indicated that the fiber-optic measurements can accurately locate the swelling and compressive zones.During the loading process,the interlock between calcareous sand particles was detected,which increased the internal friction angle of soil.The foundation deformation above the sliding surface was dominated by compression,and the soil was continuously compressed beneath the sliding surface.After 26e48 h,calcareous sand swelling occurred gradually above the water table,which was primarily dependent on capillary water.The swelling of the soil beneath the groundwater table was completed rapidly within less than 2 h.When the groundwater table and load remain constant,the compression creep behavior can be described by the Yasong-Wang model with R2¼0.993.The daily periodically varying in situ deformation of calcareous sand primarily occurs between the highest and lowest groundwater tables,i.e.4.2e6.2 m deep.The tuff interlayers with poor water absorption capacity do not swell or compress,but they produce compressive strain under the influence of deformed calcareous sand layers.

关 键 词：Distributed fiber optic sensing(DFOS) Calcareous sand Optical fiber Optical frequency domain reflectometer (OFDR) Soil foundation settlement 

分 类 号：TU441[建筑科学—岩土工程] TU46[建筑科学—土工工程]