热脉冲法监测集中渗漏的模型试验

基于光纤布拉格光栅(FBG)传感系统,提出了适用于土石坝心墙集中渗漏监测的热脉冲法。采用由传感加热单元、稳压电源、调压器、光纤光栅解调仪组成的监测系统进行了集中渗漏监测的模型试验。首先进行了骨料干燥和湿润条件下的试验,试验结果表明,采用温升作为判别指标难于对渗漏状态作出准确判断,为此定义了2个无量纲的判别指标γ和ξ。采用两种渗漏流量进行了试验,并分别采用γ和ξ进行了渗漏状态的识别,结果表明2个判别指标均能进行渗漏的准确定位,且能定性反映渗漏强度的大小,采用ξ作为判别指标的识别效果优于γ。

Model experiment for concentrated leakage monitoring by heat pulse method

Based on the fiber Bragg grating (FBG) sensing system, heat pulse method is proposed for concentrated leakage monitoring in core rockfill dam. Model experiment was carried out with monitoring system composed of sensing-heating unit, regulated power supply, booster and FBG demodulator. At first, the aggregate was in dry and moist condition respectively. The experimental results show that it is difficult for temperature rise to make an exact identification to leakage state, so two dimensionless distinguishing indices ? and ? were defined; where ? was related to seepage velocity and ? was related to water table gradient. Then, two cases with various leakage flow rates were carried out and the leakage state was identified by ? and ? respectively. The results show that both ? and ? can locate the leakage position exactly and can reflect leakage intensity qualitatively. The identification effects by using ? as distinguishing index are better than ?