流场拟合原理的基坑渗漏检测系统设计与实现

摘要

A foundation pit leakage detection system was designed according to flow-fitting principle. The method was proved by theoretical analysis and model experiment. Using switching device MOSFET to make up transmitting bridge, it can transmit 1 Hz bipolar square wave. The wave passed through diaphragm wall and formed artificial electric field. On one side of diaphragm wall, 1 Hz signal was acquired in artificial electric field by distributed electrode switching equipment, high precision ADC ADS1278 and upper computer software compiled by LabVIEW. Making Fourier transform with acquired signal, odd harmonic was extracted to draw equipotential line. According to the comparability of flow fluid field and electric current field, the flow fluid field and determine leakage position were discussed through analyzing the artificial electric field with equipotential line and current density. The results show that compared with other foundation pit leakage detection methods, this system has advantages of having simple structure and low power consumption and being easy to use. It can determine leakage position accurately and quickly.%根据流场拟合原理设计一种新型便捷的基坑渗漏检测系统，通过理论分析和模型实验验证方案的可行性。采用开关器件MOSFET设计发射桥路，在地下连续墙两侧发射1 Hz双极性方波形成人工电场；在地下连续墙一侧，采用分布式电极切换装置和高精度模数转换芯片ADS1278以及利用LabVIEW编写的上位机软件组成接收系统接收人工电场中的1 Hz信号；对接收到的信号进行快速傅里叶变换，提取信号1，3，5，7等奇次谐波的幅值绘制电势等位线图，根据水流场和电流场的相似可比性，通过分析电势等位线图和电流密度分析人工电场特性，从而分析水流场特性，确定基坑渗漏处的位置。研究结果表明：与其他基坑渗漏探测方法相比，该系统简单易用，功耗低，能够快速准确找到基坑渗漏处的位置。