An innovative Time Domain Reflectometry(TDR)sensor to monitor earthquake induced void redistribution in layered soils  

作　　者：Quan Gao Xiong Yu 

机构地区：[1]Department of Civil Engineering,Case Western Reserve University,2104 Adelbert Road,Bingham 211A,Cleveland,OH 44106–7201,US [2]Department of Civil and Environmental Engineering,Case Western Reserve University,2104 Adelbert Road,Bingham 237,Cleveland,OH 44106–7201,USA

出　　处：《Intelligent Geoengineering》2024年第1期78-87,共10页智能岩土工程(英文)

基　　金：supported by the Saada Family Fellowship to Quan Gao.

摘　　要：Liquefaction induced soil void redistribution,i.e.,the formation of thin water film between soil layers,has been identified as an important trigger of ground liquefaction occurring in stratified soils with embedded low permeability layer.Conventional liquefaction assessment of soils are conducted on uniform soil samples,which do not capture the liquefaction due to void redistribution and therefore,potentially underestimate the liquefaction occurring in the field conditions.The void redistribution,however,has not been directly validated due to lack of experimental tools for such measurements.This paper presents an innovative high resolution Time Domain Reflectometry(TDR)sensing system to directly quantify the development of thin water film in layered soils.A new spiral TDR sensor is designed and fabricated with the assistance of 3-D printing technology.A spiral sensor design is proposed to achieves high spatial resolution and sensitivity in detecting thin water film.The new spiral sensor is applied to monitor the dynamic evolvement of water film under static and dynamic conditions.In the static tests,water films with different thickness are generated between two saturated sand layers using special experimental setup.The testing results indicate that the spiral TDR waveguide has capability to detect water film as thin as 1 mm.In the dynamic experiments,the onset and evolution of interlayer water film is produced in stratified soil profile with shaking table excitation.It includes TDR system with fast signal acquisition.An algorithm is developed to analyze TDR signals to determine the thickness of water film based on the dielectric mixing model for soil-water mixture.The thickness of interlayer water film by analyzing recorded TDR signal agree reasonably well with the results of direct physical measurements.Overall,this study demonstrates the potential of an innovative TDR sensor to provide real time monitoring of water film developed in layered soils subjected to seismic ground shaking,and therefore provide a tool

关 键 词：Void redistribution Water film Time domain reflectrometry Spiral sensor 

分 类 号：S15[农业科学—土壤学]