Dynamic Analysis of Fill Dams and Some Examples

Narrowly speaking, dynamic analysis refers to the response analysis carried out to determine stress or deformation, considering only the earthquake force. In the case of a fill dam, however, the static initial stress conditions considerably affect the stress developed during an earthquake as well as the ultimate stability. As such, we have included the analysis of static initial stress and deformation here. Efforts are ongoing to accurately estimate the behavior of fill dams during earthquakes based on the development of finite element methods and true representation of the nonlinear constitutive relationship of the soil subjected to cyclic (repetitive) loads, in order to precisely estimate the behavior of a fill dam during an earthquake. This trend is on the rise. Therefore, various methods for dynamic analysis are being proposed even today [ 23 – 26 ]. Figure V.17 shows one such method that is simple and widely used. This method is divided into two stages: analysis of static initial conditions and analysis of earthquake response. The first stage is further divided into the following states. Stress-deformation analysis upon completion of embankment (embankment analysis): Nonlinear sequential analysis which simulates the filling process using the finite element method. This is a step in the analysis to determine the stress-deformation condition prior to an earthquake. The number of filling layers may be set between 8–10. Stress-deformation analysis during reservoir impoundment (reservoir impoundment analysis): In this step the stress and deformation due to buoyancy, static water pressure and seepage force arising out of water storage are calculated when reservoir impoundment is carried out after completion of embankment. In this case, quite often the analysis is first carried out considering the force due to reservoir impoundment alone for the sake of simplicity and then the initial stress-deformation condition prior to the earthquake is determined, compounding the aforesaid results together with the stress or deformation after embankment has been completed. Fig. V.17 Flow chart showing dynamic analysis using the finite element method. A flowchart illustrates the sequential process for analyzing stress, deformation, and stability in embankments during construction, reservoir filling, and earthquakes. It begins with Stress, deformation during embankment, which includes conditions of analysis such as the division of elements and layers, nonlinear material properties, and nonlinear sequential analysis. https://www.w3.org/1999/xlink" xlink:href=" https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781003761105/4dfa533d-270c-471b-bc3c-7a8180a94a3e/content/pg033-001.tif "/>