热脉冲法监测土坝集中渗漏的数值仿真

 基于温度示踪法的基本原理，结合心墙堆石坝的温度分布特征，进行梯度法与热脉冲法的选型对比，验证梯度法监测心墙堆石坝集中渗漏的不足。鉴于此，基于FBG传感系统，提出适用于土石坝心墙集中渗漏监测的热脉冲法。该方法以多孔介质–热源–FBG的共轭传热数学模型为理论基础，首先采用ADINA进行数值模拟，得到温升与渗流速度、加热功率的关系。随后，进行心墙堆石坝集中渗漏的数值模拟，得到各监测剖面的渗流速度分布。根据温升与渗流速度、加热功率的拟合公式，将其换算为温升分布，进行集中渗漏监测的数值仿真。结果表明：该方法能进行渗漏通道的准确定位，监测系统离心墙下游面越近，监测效果越好，集中渗漏强度越大，温升异常越明显。

NUMERICAL SIMULATION FOR CONCENTRATED LEAKAGE MONITORING OF ROCK-FILL DAM WITH HEAT PULSE METHOD

Based on the basic theory of temperature tracer method and combined with the temperature distribution characteristic of core rock-fill dam，the gradient method and heat pulse method were compared，which can verify the disadvantage of gradient method to monitoring the concentrated leakage of core rock-fill dams. So heat pulse method based on FBG(fiber Bragg grating) sensing system was proposed for concentrated leakage monitoring in core rock-fill dam. The mathematic model of conjugated heat transfer among porous media-heat source-FBG was proposed as a theoretical basis for this method. At first，the relationship among temperature rise，seepage velocity，and heating power was obtained by numeral simulation with ADINA software. Then numerical simulation for concentrated leakage in core rock-fill dam was executed to obtain the seepage velocity distribution of every monitoring section. According to the fitting formula among temperature rise，seepage velocity，and heating power， the numerical simulation for concentrated leakage monitoring was carried out by converting the seepage velocity distribution to temperature rise distribution. The results show that the new method can be applied to exactly locating the leakage position. The smaller the distance between sensing system and downstream face of core is，the better the monitoring effect is. The higher the concentrated leakage intensity is，the more obvious the difference of temperature rise is.