The Research On Theory And Application Of The Flow-fitting Method For Detection Of Piping And Leakage In Dykes And Dams

Geophysical exploration technology has played an important role in detection of the piping and seepage in dykes and dams, but because geophysical exploration technology is an indirect method, and each method has its own conditions,limitations and multiple solutions, especially the traditional geophysical detection methods are helpless when dealing with the piping and leakage, whose depth of burial is greater than its spatial size.At the same time, the results of these methods are not fit for emergency reuse work in flood season. The title of this paper comes from the major project "Research on Characteristics of flood and Approach to Disaster Reduction"(Item Number:50099620) jointly funded by Natural Science Foundation and the Yangtze River Water Resources Commission, and Ministry of Science and Technology Project "Research on rapid detection technology of the hidden trouble in dams and equipment development" (item number:2000 science and social welfare expenditure in agriculture special), based on the flow fitting method for detecting the piping and leakage in dykes and dams,which was put forward by academician He Jishan, this paper carries out systematic study on the theories and engineering application of the flow-fitting method, and lay a solid foundation for optimization and upgrading of detection system of the flow fitting method.The main research contents include the fitting theory between flow fluid field and electric current field, the numerical simulation of the flow-fitting method, the physical analogy research of the flow-fitting method, and the engineering application research of the flow-fitting method under different conditions.In the study of fitting theory between the flow fluid field and electric current field, based on the derivation of the basic principle of the flow-fitting method, the similarities between the flow fluid field and electric current field are confirmed in theory. Through analytical analysis, the feasibility of fitting to flow fluid field of the piping and leakage through fixed-point-source is verified, according to this result, the fitting relation of current density and velocity distribution of flow field are analyzed theoretically under several kinds of ideal situations,which offer the theoretical foundation for further analysis and calculation of the flow-fitting method for the detection of the piping and leakage in dykes and dams.In the numerical simulation of the flow-fitting method, that the temperature field is used to simulate the electric current field is put forward, through the numerical simulation of the piping and leakage in dykes and dams,the characteristics of the three components of the current density are obtained:X component will produce a bipolar anomaly at the inlet site of the leakage, Y component and Z component will have an extreme value, and Z component has the best effect to distinguish the leakage anomaly, the current density vector converges at the inlet site of the leakage.On this basis, the effects of underwater interferent with low reisitivity, the inclining angle of probe,and the distance from the infinite electrode on the results of detection are done with numerical calculation, the results show that these factors have limited impact on the measurement results of the flow-fitting method.In the physical analogy research of the flow-fitting method, through a series of indoor and on-the-spot simulation tests,the relevant relations between the anomaly of flow fluid field and the anomaly of electric current field are further defined, and lays a foundation for the production tests of the methods and technologies,the research and development of the equipment, and at the same time verifies the validity of results of numerical simulation.In the engineering application research under different conditions, the method is applied to detecting the leakage zone of Zhushuqiao reservoir of Liuyang City, Gejinkou gate of Hanshou County and Hongze lake embankment, accurately found out the inlet zone of these piping and seepages,and had offered the scientific basis for prompt administration of these projects.The successful application of these case studies show that the flow-fitting method can be used for the fast survey of the large reservoir with complicated condition, the piping and seepage of river dykes under the abominable conditions in flood season, and as well as offered the basis for finalizing the design of the instrument.The researches on the theory, numerical simulations,physical modeling test and case studies on the flow-fitting method, indicate that the flow-fitting method is an excellent detection method for piping and leakage in dykes and dams,which has the characteristics of strong anti-interference ability, high efficiency, high research, and is fit for the fast exploration task of piping and leakage in dykes and dams under various engineering conditions.