Study On The Application Of The Time Domain Reflectometry In The Swelling Soil

Time domain reflectometry(TDR) is a new instrument to measure the soil moisture . Compared with the traditional method, it can measure the moisture quickly and pricely without destroying the soil mass. But it needs special calibration before used. And the cranny existed in the swelling soil influence the results. This thesis focus on the special calibration in the expansive soil and the influence of the cranny based on the tube TDR system.Indoor and outdoor calibration were carried on, the results of the calibration were analyzed from the point of bound water. We also calibrate the desiccation samples to simulate the cranny in the soil mass. The results of all these calibrations were compared ,and the reason of difference was analyzed.The cranny in the soil mass was sorted into three types: the gap around the tube, vertical cranny and horizontal cranny . Each kind's influence on TDR was studied.