高速公路路基湿度场空间分布快速测试及评价方法研究

A Fast Test and Evaluation Method for Spatial Distribution of Moisture Field of Highway Subgrade

为了评价路基土湿度场的空间分布,研究了一种基于振动测试及电测量的高速公路路基湿度场空间分布快速测试及评价方法。选取某多雨潮湿地区在建高速公路的一段路基作为等比例试验路基模型,布置注水系统以改变路基的湿度场,设计了含水率分别为17%、19%及20%的3种路基模型Ⅰ、Ⅱ、Ⅲ;分别采用振动测试、温湿度传感器测试、高密度面波测试及电测量4种方法进行测试,测试指标包括路基土的含水率ω、弹性波振幅A、剪切波速度V _(shear)、视电阻率ρ_(s);分析了弹性波振动衰减率及电阻率分布,评价了路基湿度场的空间分布;将电测量测得的视电阻率换算成含水率ω_(ρ),并与由温湿度传感器测得的含水率ω_(sensor)进行了对比分析。结果表明:随着路基含水率由17%提高至20%,路基振动衰减率增长了20%~30%,剪切波速度减小了16%,验证了采用振动测试能够快速评价路基湿度场的变化;电测量法换算含水率ω_(ρ)与温湿度传感器测量换算含水率ω_(sensor)的相对误差绝对值在1%~3%范围内,验证了电测量方法能够较准确地评价路基湿度场的空间分布。

In order to evaluate the spatial distribution of moisture field of subgrade soil,a fast test and evaluation method of spatial distribution of moisture field of highway subgrade based on vibration test and electrical measurement was studied.A section of subgrade of an expressway under construction in a rainy and humid area was selected as an equal scale test subgrade model.The moisture field of the subgrade was changed by the water injection system.Three subgrade modelsⅠ,ⅡandⅢwere designed,and the designed moisture content was 17%,19%and 20%respectively.4 kinds of methods such as vibration test,temperature and humidity sensor test,high-density surface wave test and electrical measurement were used for testing respectively.The test indicators included moisture content of subgrade soilω,elastic wave amplitude A,_(shear)wave velocity V_(shear)and apparent resistivity ρ_(s).The attenuation rate and resistivity distribution of elastic wave vibration were analyzed,and the spatial distribution of subgrade moisture field was evaluated.The apparent resistivity measured by the electrical measurement was converted into water content ω_(ρ),which was compared with the moisture content ω_(sensor) measured by the temperature and humidity sensor.The results show that as the moisture content of the subgrade increases from 17%to 20%,the vibration attenuation rate of subgrade increases by 20%~30%,and the_(shear)wave velocity decreases by 16%,which verifies that the vibration test can quickly evaluate the change of subgrade moisture field;and the absolute value of relative error of moisture content ω_(ρ) converted by electrical measurement method and ω_(sensor) converted by the temperature and humidity sensor test,is in the range of 1%~3%,which verifies that the electrical measurement method can accurately evaluate the spatial distribution of subgrade moisture field.