In-plane transversal normal stresses in the concrete face of CFRD induced by the first-dam reservoir filling

To evaluate the effects of dam height, valley narrowness and width of concrete slabs on the first-dam reservoir filling in-plane transversal normal stresses in the concrete face of CFRD＇s, 3D finite difference analyses were carried out. Behavior of rockfiU dams considered in this study was defined from the monitoring of a number of 3D sets of pressure cells and extensometers installed in three large dams in Mexico. The 3D analyses results show that high in-plane transversal compressive stresses develop within the concrete panels located in the central concrete face zone upon dam reservoir filling loading. Likewise, in-plane induced tensile transversal stresses in the zones near the abutments increase the potential of slabs cracking and damaging the waterstops in-between the vertical and perimetral joints. From the results of the 3D finite difference analyses, a simple method to estimate in-plane normal stresses in the concrete face is advanced and through comparisons with the results of a 3D case numerical study, its accuracy assessed.

Dynamic in-plane transversal normal stresses in the concrete face of CFRD

Severe earthquakes can induce damages to Concrete Face Rocldill Dams (CFRDs)such as concrete cracking and joint's water stops distressing where high in-plane transversal normal stresses develop.Although these damages rarely jeopardize the dam safety,they cause large water reservoir leakages that hinder the dam functioning.This issue can be addressed using well know numerical methods;however,given the wide range of parameters involved,it would seem appropriate to develop a simple yet reliable procedure to get a close understanding how their interaction affects the CFRD's overall behavior.Accordingly,once the physics of the problem is better understood one can proceed to perform a detailed design of the various components of the dam.To this end an easy-to-use procedure that accounts for the dam height effects,valley narrowness,valley slopes,width of concrete slabs and seismic excitation characteristics was developed.The procedure is the dynamic complement of a method recently developed to evaluate in-plane transversal normal stresses in the concrete face of CFRD's due to dam reservoir filling [1].Using these two procedures in a sequential manner,it is possible to define the concrete slab in-plane normal stresses induced by the reservoir filling and the action of orthogonal horizontal seismic excitations acting at the same time upstream-downstream and cross river.Both procedures were developed from a data base generated using nonlinear static and dynamic three-dimensional numerical analyses on the same group of CFRD's.Then,the results were interpreted with the Buckingham Pi theorem and various relationships were developed.In the above reference,the method to evaluate the concrete face in-plane transversal normal stresses caused by the first reservoir filling was reported.In this paper,the seismic procedure is first developed and then through an example the whole method (dam construction,reservoir filling plus seismic loading)of analysis is assessed.