Static And Dynamic Characteristics Analysis On The Junction Of Inserted Type Composite Dam

The composite dam is an economic dam type that takes good advantage of topographicconditions. Generally, it consists of concrete gravity dam (or buttress dam) and earth damwhich joint together. Because there was no satisfactory solution to problems about junctionform and seismic design of the junction between concrete and soil in the high intensiveseismic region, the high composite dam was seldom built there and there was not enoughrelative research.In this paper, the inserted type composite dam was selected to study. Based on finiteelement method, simulating the actual process of both construction and water conservation ofthe earth dam, adopting thin layer element on the contact surface of concrete and clay core, aregular composite dam example and Shankou Composite Dam were analyzed The analysismentioned above involved in three-dimensional nonlinear finite element static and dynamiccharacteristics. The main work and conclusions are as follows:1. Forms and characteristics of composite dam were summarized by introducing severalcomposite dams at home and abroad. Subsequently, after looking back the state of domesticand overseas research and development, main problems of the composite dam were summedup during periods of its construction and operation.2. Theory of Finite Element Method, as well as two-surface constitutive model presentedby Shen Zhujiang from Nanjing Hydraulic Research Institute and equivalent nonlinearviscoelastic model, was introduced. Afterward, principle of construction loading wasgeneralized, and then theories of interface and interface element were reviewed. At the sametime, selection of t, the thickness of thin layer element, was discussed.3. Thoughts of modeling and methods of mesh generation for the inserted type compositedam were introduced, and the message of nodes, elements and constraints which are needed instatic and dynamic calculation are drawn by the large universal Finite Element analysissoftware ANSYS. Results of mesh generation showed that the mesh precision requirement ofthe regular composite dam example and Shankou composite dam in this paper was reachedand the mesh precision was reasonable.4. It was discussed that whether the calculating parameter proportion-weighted of thinlayer element had large influence on static and dynamic response of the composite dam junction or not. Results of calculation showed that thin layer element plays a role ofalleviating stress concentration on concrete surface due to great disparity between concreteand clay core and influence of modulus selection of thin layer element on seismic response islittle. Thus adopting thin layer element to simulate contact surface is effective and feasible.5. After selecting material parameter proportion-weighted 1:1, the regular compositedam and Shankou Composite Dam, were analyzed, conceming about three-dimensionalnonlinear static and dynamic characteristics. Results of calculation showed that compressivestress of inserted concrete near to the dam foundation, especially near to the downstreamsurface, was large and also small tensile stress occurred near to the top of inserted portion. Italso showed that acceleration response on the top of inserted portion is great under earthquakeloading, with an amplification coefficient exceeding 2.0. Finally, referential engineeringmeasures to improve operation reliability of the inserted type composite dam were putforward.