Research Of TDR Monitoring Technology For Landslide Hazard

Geological hazards are variety in our country, and the sudden events of geological hazard have been concurrent frequently. The events have already brought about great economic losses. Studies on the technology of geological hazard monitoring and gaining useful information of geological hazard can provide appraising the stability of the body of geological hazard with a basis. Implementing dynamic monitoring to geological hazard not only can provide kinematics and dynamics characteristic of the deformation body, but also establish a basis of geological hazard prospecting, governing construction and so on. It can provide the correct valuation stability and prevention and cure construction design with a basis.Considering the each aspect such as causing a factor to happen and forming mechanism of landslide, the characteristic of landslide is the uncertainty. But practical experience many years indicates that we can know the laws of happened and developing landslide as long as monitoring and handling to monitoring a data to landslide. At present the technology methods of monitoring landslide are varied. Progress with the science and technology ceaselessness, the monitoring technology of landslide also is in uninterrupted growth. By relevant research of home and abroad, it indicates that the Time Domain Reflectometry can be used for landslide dynamic monitoring. Based on the project "the Study and Example Application of geological hazard early warning key technology method" (project serial number: 1212010340205), the monitoring technology of landslide based on TDR is studies in this paper. It will be beneficial to popularize the monitoring technology of landslide based on TDR.For analyzing and studying the forming mechanism, activity state and developing trend of landslide, it is very important that the landslide has being observed. Adopt the TDR technology to monitor landslide, the development of deformation and displacement of deep headquarter of landslide is able to know. It is able to realize to deformable dynamic monitoring of landslide, and provide the reliable data and science basis for early warning and forecasting study of monitoring landslide.Adopting the TDR technology to monitoring the landslide, according to the reality landslide, the appropriate monitoring location is chosen on the landslide body at first. The monitoring bore is arranged in selected location. The bore is reaching the stable stratum directly passes through the face sliding. After monitoring borehole being completed, the testing coax is vertically put to inside the borehole. And then backfill, it makes the coax and vicinity rock or soil to glue together. Make use of special monitoring instrument to monitor the coax change. It is able to ascertain the position of the sliding face and know the dynamic displacement information of different depth on landslide.Knowing the technology and method of monitoring landslide based on TDR sufficiently, TDR monitoring system is designed for the characteristic of monitoring landslide. According to the thought of designing scheme, the hardware and software in the monitoring system are designed and debugged. When designing the monitoring system, this paper has discussed two key technology problems. One is impedance match between the signal source and the coax. Another is the drive ability of the generator output. These two problems must be solved. The TDR monitoring system is the system based on portable type industrial control computer, it realizes functions such as the collecting data, controlling and handling information.For knowing the relation of coax deformation and TDR signal, in developing TDR monitoring system process, the coax simulative test is carried out according to the reality needs of monitoring landslide. Pass the coax simulative test, gain the experiment data. And carrying out appropriate treatment and analyses, probe the mathematics relation between coax deformation and TDR signal change. The data has carried out treatment and analysis on interior simulative test. The curve of between the change of shearing, stretching displacement and TDR change has carried out the data fitting. The first step has been got the correspondence relational expression between the change of shearing, stretching displacement and TDR change. It will be beneficial to popularize the monitoring technology of landslide based on TDR. By the fact that the interior simulative test can know, there does exist certain correspondence relation of coax deformation and TDR signal amplitude. This relation is able to be used to monitor landslide. At the same time, the interior experiment has verified that the system design scheme what is submitted in this paper is feasible. During actual landslide monitoring and early warning, the product of abnormal maximum value and abnormal width value of TDR is able to expresses damaged degree of coax, and it is able to be the state breakdown degree of landslide.The ultimate purpose of studying TDR monitors method and developing TDR instrument is for applying TDR to monitor landslide in the actual monitoring project. For accumulating experience of the study and the application of TDR, based on the investigation project of land and resources, TDR monitoring technology has been applying as an example in Wu Shan demonstrates station of Ministry of Land and Resources geological hazard early warning. And contrasted with the routine detecting instrument, TDR monitoring technology has also applying in Sichuan Yaan. Judging from actual observation result, TDR is able to detect the deformation of landslide. And monitoring the location of landslide deformation is identical to deformation position of borehole to reveal. It is also the same with borehole incline instrument. It can be seen from it that TDR technology be used landslide monitors.By the field monitoring experiment, it is able to know, there are the following merit for monitoring landslide based on TDR:(1) Save time: Monitor process of entire borehole is completed within very short time (several seconds).(2) Cheap cost: Compared with the casing pipe making use of the borehole incline instrument, the coax cable cost is comparatively low.(3) Accurate location: By TDR technology monitoring landslide, the face of slippage is accurately given out, and the accuracy of location are higher. But, there is a shortage in TDR technology monitoring landslide, and it shows mainly that it is very difficult to ascertain direction of landslide glide by TDR technology to monitor landslide.The subject of this paper is to study on the technology of monitoring landslide based on TDR. The main conclusions of this paper are following:(1)It is one kind of new technique to adopt Time Domain Reflectometry to monitor landslide in the actual project. It is fit for each stage of various type landslides.(2) The theory of transmission line is the basis of Time Domain Reflectometry. With studying on TDR monitoring landslide, it will be one kind of practical technology in monitoring landslide. And it is used for actual project broadly.(3)With the development of electron technology, computer and communicating, it will be easy to structure TDR landslide monitoring system especially. It will realize long-range real time dynamic monitoring landslide. The monitoring datum is providing one kind of reliable basis for the project of geological hazard monitoring and early warning. So it will boost development of landslide monitoring technology in our country.(4) Compared with tradition monitoring landslide technology, there are many merits such as save time, cheap cost, accurate location, if making use of the TDR technology to monitor landslide. But, there is a shortage in TDR technology monitoring landslide, and it shows mainly that it is very difficult to ascertain direction of landslide glide by TDR technology to monitor landslide.(5) By interior simulative test, a coax deformable basic law has elementarily been gained. It has been provided the certain reference basis for landslide monitoring. At the same time, it has been provided one kind of feasible thought of studying on landslide monitoring in the future.(6)Perceived by the field applying experiment, TDR is able to ascertain the dynamic information and the developing trend of landslide qualitatively. At present, it is not able to give out the complete quantify explains in the deformation of landslide, but it will have been able to demonstrate its unique advantage that there is large range in deformation monitors.