Study On Vibration Modality Theory For The Light Thin Plate Retaining Wall And Its Application

At present light thin plate retaining wall is a very popular retaining structure. So its engineering quality and healthiness of the existing structures are very important to ensure the safety stability of infrastructure and security of lives and possession. But nowdays the conventional method for quality detection of wall structure is destructive sampling test method which is not efficient,irepresentative and can not meet the need of engineering detection. Thus it is necessary to study a handy, lossless and effective method for health diagnose to improve and even substitute the conventional method. Therefore based on the basic principle of structure dynamics and the theories of energy method, reciprocal theorem, variational principle and so on, by vibration modality analysis and modern signal process technology for distilling experimental modal parameters, built on the project of"studies on landslides disaster forecast and its new technique about security capability"(No. 2006AB7003) for Chongqing key science and technology and the program of"studies on the theories about damage detection and intelligent diagnosis for geotechnical retaining structure"(No. 50625824) for National Science Fund for Distinguished Young Scholars, through theory study, numerical simulation, field and laboratory test the paper studies the vibration modality theory, test and distilling technology of experimental modal parameters, damage identification and quality assessment, soil pressure detection of light thin plate retaining wall system which comprises the dynamic interaction of structure and semi-infinite soil. In this dissertation the main original work includes:①Study on bearing mechanism and vibration modality theory of the cantilever retaining wall. Based on the thin plate simplified model with the winkler foundation, by energy method, variational principle,reciprocal theorem and other theories, the static bending analytical solution , motion equation for forced vibration with concentrated simple harmonic load and the frequency formula of constant thickness cantilever retaining wall are deduced. Then by improving Kantorovich method the natural frequency formula for constant thickness cantilever retaining wall and vibration differential equtation for variational thickness cantilever retaining wall are also deduced.②Study on vibration modality theory for the light thin plate retaining wall. Based on the semi-infinite elastic foundation the vibration modal differential equtation with dynamic interaction between structure and soil is deduced. Then its solving principle is analysed. Finally, Based on the simplified model with the winkler foundation the vibration differential equtation, boundary conditions, coupled equation are analysed.③Study on technology for the experimental modal test and parameter identification of the light thin plate retaining wall. The study on the technology of modal test inspiring and parameter identification further process are emphasized. Then the main factors which influence the energy magnitude and distributing and the control technology for force spectral capability of the DFC-2 high elastic energy-gathering hammer are studies.④Study on theory modal and health diagnose of the cantilever retaining wall by superposition method. Through field test, the modal shape and modal frequency of the cantilever retaining wall system are tested and computed. Then based on the superposition method model the health diagnose method for the local damage and the two typical failure modes for slippage, capsizal are studied.⑤Study on numerical simulation of modal for the light thin plate retaining wall and soil pressure back analysis. The chapter studies the processing methods of dynamical boundary and contact surface coupling between structure and soil for numerical simulation of the modal for the retaining wall with anchor. Thus the key problems of vibration modality simulation for structure and soil dynamic interaction system are solved. Then through the relation between parameter and soil pressure and the hypothesis of soil pressure distributing the soil pressure are back analyzed by the index of frequency approach between finite element modal method and test modal method. The conclusion indicates that the precision of back analysis is connected with the hypothesis of soil pressure distributing.All the above research forms the basis theory system of vibration theory modality and experimental modal for the light thin plate retaining wall system and its health diagnose technology. It is important to improve management of engineering quality, enlarge the application of vibration modality theory with health diagnose and stability analysis for the light thin plate retaining wall system and enhance the ability of disaster prevention and reduction for geotechnical engineering.