Mechanics Cause Analysis For Sluice Pier Crack Of Liaoning Shenwo Concrete Gravity Dam

Massive concrete structure is the important structure form of water conservancy project, however, concrete material can resist huge pressure but small tensile stress and causes large amount of heat after casting, which result in the destructive crack of structure easily. So far, there is so much study on crack causes for mass concrete, but the study on the macroscopic crack patterns produced by different crack causes is less, so reinforcement measures can not be taken aiming to specific cracks causes. Therefore, research on the macroscopic crack patterns under different fracture cause of cracks is extremely urgent.There are many advantages for the analysis of the problem of cracks in concrete with extended finite element method, extended finite element method is adopted to analysis the cause for sluice pier cracks of Shenwo concrete gravity dam in this paper. Causes of crack under the temperature stress, concrete shrinkage stress and the concentration stress of sluice piers are discussed, and compare the crack and the actual crack. Mainly conclusions are obtained in the following aspects:(1) Through the analysis of the crack forms,distribution of location and quantity in the Liaoning Shenwo concrete gravity dam, it is concluded that majority cracks which are caused by tensile stress appear dentate and vertical, meanwhile the cracks are mainly distributed in the intermediate place of the pier. Through analysis of temperature load in construction and operating period along with hydrostatic pressure to the sluice pier, combining with hydraulic observation data, it is concluded that sluice pier crack are caused by temperature stress,concrete shrinkage and hydrostatic pressure transferred by the sluice gate.(2) Based on finite element method, established the concreting hierarchical model and adopted sequence stress coupled analysis; change of concrete temperature field for each layer sluice pier is simulated after casting along with age growth. The result shows that internal temperature change quickly, and the external temperature change slowly after concrete casting concrete construction process has certain effect on temperature field analysis.(3) With the sluice pier of Shenwo concrete gravity dam for engineering background, based on the extended finite element method to establish the numerical analysis model of concrete crack, numerical analysis is conducted for course of formation of sluice pier crack by using the large nonlinear extended finite element method. Through comparative analysis with the actual cracks, it is concluded that longer vertical cracks in different position are caused by temperature,concrete shrinkage and reservoir water pressure, but shorter vertical cracks are caused by temperature, horizontal cracks may be caused by temperature and concrete shrinkage.