| Landslide geological disasters are very sudden and destructive.China has a complex geological environment conditions,which is one of the most landslide developed areas in the world.To effectively avoid or reduce the huge casualties and property losses has been caused to the local people in the landslide area,it is essential to carry out monitoring and pre-warning in potential landslide areas.Landslide deformation failure is resulting of multi-field coupling,the traditional deformation-field displacement monitoring is only based on a single displacement-time change,which cannot comprehensively reflects the overall development of the landslide deformation.While through the multi-field characteristic information monitoring such as seepage-field,displacement-field,stress-field and temperature-field,et al,establishing multi-field characteristic parameter monitoring methods and techniques is a effective way to systematically reveal the evolution mechanism and realize landslide prediction and prevention.At present,Landslide multi-field monitoring are mainly through drilling or excavation to lay a variety of sensors to collect the deep soil multi-field information of landslide.All kinds of sensors at each point are either distributed independently or concentrated in the hole.It is difficult to accurately obtain multi-field data of landslides with strong correlation under in-situ conditions,and it is difficult to maintain the continuous measurement of the instrument under great landslide deformation.Thus,it is necessary to develop a off-hole multi-parameter sensing system equipment for landslide monitoring to adapt to the great landslide deformation,so as to realize the integrated,continuous and in-situ monitoring of multi-field characteristic information in key areas.However,the deep soil environment of the landslide is complex,and the system involves multi-disciplinary intersection.The equipment development still faces many technical difficulties,such as difficult integration and plenty interference of multi-sensor system,poor long-term stability of power supply and communication in/off hole,and the large disturbance when the instrument in-situ penetrating into the landslide body,et al.This thesis taking the off-hole multi-parameter sensing(OMPS)system as the main line,the key technical requirements of the OMPS system are proposed.The key technologies development such as the manufacturing of interdigital(IDT)fringe-field sensor for deep soil moisture measuring,the optimization of performance for magnetic resonant wireless power transfer(MR-WPT)under great landslide deformation and conductor interference,the electromagnetic(EM)compatibility design for multi-sensor integration,and the penetration structure design with low soil disturbance,et al.are carried out respectively.It is preliminary formed a set of OMPS system suit for large deformation of landslide,which integrates the multi-field parameters of landslide evolution monitoring such as soil pressure,soil moisture,seepage pressure,soil temperature.The practicability of the OMPS system were verified by field test.The main research work and conclusions are as follows :(1)Modeling and optimization for IDT soil moisture sensor.Aiming at the deficiency of sensor size and accuracy in conventional dielectric moisture sensors,the IDT fringe-field FDR measurement method is introduced.The equivalent theoretical model of the IDT sensor under the fixed electrode area is established by using the conformal mapping technology.Combined with EM simulation,the influences of IDT electrode size and shape on the sensor penetration depth and sensitivity are analyzed systematically,and the optimal interdigital electrode size and shape of the sensor are determined.Several IDT sensor prototypes were fabricated,the sensor calibration,functionality and performance verification tests were carried out based on the thermogravimetry.Compared with the existing research,the sensor developed in this thesis had good sensitivity and resolution while reducing the volume.(2)Performance optimization for the magnetic resonant wireless power transfer(MR-WPT)system under conductor dielectric interference.Regarding the problem of MR-WPT system performance degradation caused by the induced eddy loss in the nearby conductor and water medium,the eddy loss model is established,the variation of eddy loss with resonant-frequency is analyzed.The expression of system power transfer efficiency(PTE)under conductor interference is derived through the equivalent circuit model(ECM).Based on this,the influence of resonant-frequency(Rf)on system performance is analyzed,and the existence of optimal Rf to maximize PTE is proved.The conductor slotting method to reduce the eddy loss is proposed,the influence of slotting specifications on PTE and optimal Rf is discussed with simulation,and the critical slot number and slot width are determined.Finally,the theoretical results were verified by experiments,appropriate slotting can further increase the PTE up to 67% on the basis of the optimal Rf,and the MR-WPT and communication prototype for landslide monitoring is designed and implemented.(3)Dynamic stability improvement of the in/off-hole MR-WPT system under the great landslide deformation.To solve the problem of system PTE drop caused by the coil position change under great landslide deformation,a dynamic MR-WPT system with double receiver structure is introduced,and a passive method for maintaining stable and efficient power transfer under cross coupling is proposed.The expressions of PTE and optimal load are derived based on the ECM.Based on this,the system performance with / without cross coupling is analyzed,and it is revealed that the system has the optimal transmission distance to maximize PTE and the transmitter movement range to stable power transfer.Finally,the theoretical results are verified by experiments,the system can achieve more than 75% efficiency(fluctuating within 12%)when the system moves in the optimal range.Compared with previous studies,the proposed system can achieve efficient power transfer with less PTE fluctuation when the transmitter position changes dynamically.(4)Low soil disturbance structure design for in-situ penetration.Considering the requirements of multi-parameters in-situ monitoring and low soil disturbance during probe-claw penetration,the theoretical model of penetration resistance is constructed based on the bearing capacity theory,and the stress and strain characteristics of probe-soil in the penetration are analyzed.Combined with a large number of FEA simulations,the relationship between the wedge angle,soil depth and penetration speed and the penetration resistance is obtained,which provides a reference for the probe and penetration structure design,manufacture and motor selection.(5)Electromagnetic compatibility optimization and design of multi-sensor probe-claw.For the narrow spatial layout of the probe-claw,the electromagnetic distribution-distance characteristics of the multi-parameter probe-claw under the dense distribution of the sensor are analyzed by EM simulation.The gap distance and the routing mode of the low electromagnetic interference sensor which can ensure the normal operation of each sensor on the probe claw are given.The electromagnetic anti-interference ability of the installation warehouse and the routing hole of the measurement and control board is verified.(6)Debugging and field experiment for the OMPS system.The relevant design elements that should be considered in the overall system hardware and integrated packaging are proposed.The joint debugging and packaging for the multi-parameter probe-claw hardware system are completed in-lab,and each performance indexes of the system meet the design requirements.The field test was carried out on the example of Huangtupo riverside landslide No.1.The probe prototype successfully penetrated into the sliding body,and the monitoring data of multi-field parameters such as soil moisture,soil pressure and seepage pressure were uploaded normally. |
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