This is the reply to the comments by AlQasimi and Mahdi (2022) on the classification attributed to the Lake Ha! Ha! real-field test case by Aureli et al. (2021) in their review of historical ...dam-break events useful for the validation of dam-break numerical models. While admitting that this test case is affected by the data shortcomings reported by the Discussers, in the authors’ opinion, it should remain included in the group of well-documented test cases due to the large and complete dataset available in digital format. This conclusion is also supported by the fact that the Lake Ha! Ha! case was chosen as a benchmark in the framework of the 2001–2004 IMPACT (Investigation of Extreme Flood Processes and Uncertainty) European project and was then widely used in the literature for the validation of one-dimensional and two-dimensional geomorphic flood models.
Landslide dams pose enormous risks to the public because of the potentially catastrophic floods generated by breaching of such dams. The need to better understand the threats of landslide dams raises ...questions about the proper estimation of breaching parameters (breach size, breaching duration, and peak outflow rate) of landslide dams and the feasibility of applying models for estimating the breaching parameters of man-made earthen dams to landslide dams. This paper aims to answer these two questions. In this study, a database of 1,239 landslide dams, including 257 cases formed during the 12 May 2008 Wenchuan earthquake, has been compiled. Based on records of 52 landslide dam cases with breaching information in the database, empirical models for estimating the breaching parameters of landslide dams are developed. A comparison study between landslide dams and man-made earth and rockfill dams is conducted, which shows that the models for man-made earth and rockfill dams are not suitable for estimating the breaching parameters of landslide dams. Two case studies are presented to show the application of the set of empirical models developed in this paper.
Finite Element Huang, Jiandong; Duan, Tianhong; Sun, Yuantian ...
Advances in Civil Engineering,
12/2020, Volume:
2020
Journal Article
DAMs have recently been developed to be used as the damping layer in the so-called antivibration pavement to mitigate the effects of traffic-induced vibration while rare finite element (FE) modeling ...has been conducted to simulate the indirect tension to cylindrical (IT-CY) specimen test for DAMs. In the present study, the methods for the viscoelastic characterization of DAMs and the techniques to characterize the viscoelastic behavior of DAMs in FE modeling were proposed. The FE model to simulate the IT-CY test was constructed, and it was verified through the corresponding laboratory test. Good agreements were noted between the simulation results and testing results demonstrating that the FE model can provide the accurate prediction of the mechanical behavior of DAMs.
Summary
Structural health monitoring (SHM) has been widely employed to reveal the hidden safety information and to diagnose the safety status in dam engineering fields. As one of the most important ...parameters of SHM, crack opening displacement (COD) is often used to evaluate the cracks or joints of concrete dams. In this paper, a new dam health analytic perspective is introduced by integrating the data mining method into SHM field, focusing on revealing the association rules in COD monitoring data. The association rules are investigated systematically, considering the cause–effect relations between external loads and structural response, the temporal characteristics of time series for a single sensor, the spatial characteristics of monitoring data for multisensors, and the abnormal characteristics for different items of structural responses. The association relation is quantified by proposing the quantitative indexes, including support degree, confidence degree, and promotion degree. The methods are used in the COD monitoring data of the Baishan concrete gravity‐arch dam, which is located in a severely cold area in northeastern China. Results show that 4 out of 24 cause–effect association rules are extracted by calculating the association degree of monitored COD values, and 21 out of 24 crack sensors present a temporal association relationship, among which the confidence degree of two sensors reaches 100%. The variation trend of COD values is relevant with the locations of the crack sensors. These results are consistent with the dam safety monitoring theories and models, which would be very useful for extracting the SHM information between different sensors, predicting the trend of COD value and repairing the monitoring data series of COD sensors, or even for discovering an abnormal signal for the operation safety of dams.
Seepage is a main cause of dam failure, and its stability analysis is the focus of a dam's design, construction, and management. Because a geological survey can only determine the range of a dam ...foundation's hydraulic conductivity, hydraulic conductivity inversion is crucial in engineering. However, current inversion methods of dam hydraulic conductivity are either not accurate enough or too complex to be directly used in engineering. Therefore, this paper proposes a new method for the inversion of hydraulic conductivity with high application value in hydraulic engineering using an improved genetic algorithm coupled with an unsaturated equivalent continuum model (IGA-UECM). This method is implemented by a new code that fully considers engineering applicability. In addition to overcoming the premature convergence shortcomings of traditional genetic algorithms, it converges faster than Bayesian optimization and tree-structured Parzen estimator inversion algorithms. This method is verified by comparing the water head from drilling exploration and inversion. The results of the inversion are used to study the influence of a cement grouting curtain layout scheme on the seepage field of the Hami concrete-face rockfill dam in China, which is used as an engineering application case of the IGA-UECM. The law of the seepage field is reasonable, which verifies the validity of the IGA-UECM. The new inversion method of hydraulic conductivity and the proposed cement grouting curtain layout in this study offer possible strategies for the design, construction, and management of concrete-face rockfill dams.
Determination of shear strength of soil is very important in civil engineering for foundation design, earth and rock fill dam design, highway and airfield design, stability of slopes and cuts, and in ...the design of coastal structures. In this study, a novel hybrid soft computing model (RF-PSO) of random forest (RF) and particle swarm optimization (PSO) was developed and used to estimate the undrained shear strength of soil based on the clay content (%), moisture content (%), specific gravity (%), void ratio (%), liquid limit (%), and plastic limit (%). In this study, the experimental results of 127 soil samples from national highway project Hai Phong-Thai Binh of Vietnam were used to generate datasets for training and validating models. Pearson correlation coefficient (R) method was used to evaluate and compare performance of the proposed model with single RF model. The results show that the proposed hybrid model (RF-PSO) achieved a high accuracy performance (R = 0.89) in the prediction of shear strength of soil. Validation of the models also indicated that RF-PSO model (R = 0.89 and Root Mean Square Error (RMSE) = 0.453) is superior to the single RF model without optimization (R = 0.87 and RMSE = 0.48). Thus, the proposed hybrid model (RF-PSO) can be used for accurate estimation of shear strength which can be used for the suitable designing of civil engineering structures.
In China, the current seismic codes specify a single earthquake event as the design seismic load for concrete gravity dams. However, a large mainshock usually triggers numerous aftershocks in a short ...period. This paper assesses the effects of aftershocks on concrete gravity dam–reservoir–foundation systems and provides a quantitative description of the damage demands prior to and following the aftershocks. For this purpose, a set of 20 as-recorded mainshock–aftershock seismic sequences is considered in this study. The correlation between the ground motion characteristics of the as-recorded mainshocks and those of the aftershocks is examined. In order to identify the influence of the ground motion characteristics of aftershocks on the damage demands of the mainshock-damaged dams, the nonlinear behavior of the concrete gravity dams that are subjected to single seismic events and typical as-recorded seismic sequences is compared in terms of the structural damage, displacement response, and damage dissipated energy. A series of nonlinear dynamic analyses is performed to quantify the influence of aftershocks, which are selected by using different methods, on the damage demands of concrete gravity dam–reservoir–foundation systems in terms of the local and global damage indices. The results show that the aftershocks lead to an increase in the damage demands of the dam at the end of the seismic sequence when the concrete gravity dam is already damaged during the first individual seismic event and has not been repaired. In addition, the results also reveal that the repeated seismic sequences tend to underestimate the level of damage demands.
•The effects of single aftershocks on damage demands of gravity dams are quantified.•Ground motion characteristics of the mainshocks and aftershocks are discussed.•The importance of aftershocks selected by different approaches is discussed.•Repeated earthquakes tend to underestimate the damage demand level of gravity dams.
•A performance-based blast-resistance evaluation framework is proposed for gravity dam.•A modified slip stability coefficient is used to assess the dam foundation stability.•A global damage index is ...proposed to measure the risk of the dam under explosions.•Safety control criteria for blast-resistance analysis of gravity dams is discussed.
In recent years, the blast-resistance of dams under extreme explosion conditions has received more and more concerns by managers and engineers. The blast-resistance evaluation and safety control criteria for concrete gravity dams subjected to explosion loads are still controversial problems. To this end, a fully coupled three-dimensional finite element model of a concrete gravity dam is established to simulate the damage modes of the dam under various explosion scenarios. Then, a performance-based blast-resistance evaluation framework of concrete gravity dams is established in this study to consider the global safety of the dam, including the global crack evolution and the stabilities of dam head and dam foundation. According to the evaluation framework, a blast-vibration-based model for dam head safety, a modified model against sliding for dam foundation stability, and a global damage index with water retaining performance are provided in this study to discuss the global safety of the dam experienced explosions. Finally, safety control criteria of the dam are also proposed as an example, which provide theoretical support for the further protection design of the dam.
The lifetime net economic contribution of a dam that is subject to sedimentation is likely to depend on the storage capacity of its reservoir, how fast the capacity is lost to sedimentation, and the ...cost of ultimate decommissioning of the dam. A model is developed for determining the size of initial reservoir capacity of a dam to maximize lifetime net benefits, while allowing for the possibility of sediment management to extend its useful life, and accounting for dam decommissioning costs incurred when this life ends. The model is applied to a proposed hydropower dam. Baseline results are compared with those obtained from building the dam at its designed reservoir capacity. Sensitivity analysis with respect to key economic and technical parameters is also carried out to characterize differences in solutions to the cases with and without sediment management. The overall goal is to improve our understanding of optimal dam sizing under different circumstances.
Key Points
A model is developed for determining the economically efficient initial reservoir capacity of a dam that is subject to sedimentation
Possibility of sediment removal may reduce optimal initial reservoir capacity, extend lifetime of dam, and reduce dam decommissioning costs
An illustrative application of the model suggests conditions under which alternative dam sizes should be built to serve economic objectives
Uncertainties such as material randomness, manufacturing anomalies, and external loading play an important role in the design of engineering structures. Therefore, reliability-based design ...optimization (RBDO) is frequently used as a tool to guarantee economic aspects without compromising safety. In this paper, an uncertainty-aware framework is proposed for seismic optimization of structures. This algorithm is founded on the stochastic dynamic stressor, and therefore, reduces the bias due to the aleatory nature of ground motion. Safety constraints are evaluated in quantiles instead of the exact solution of reliability analysis. Kriging approach approximates the actual model, while a global search algorithm solves the RBDO problem. The proposed algorithm is used for the optimal shape design of gravity dams with a series of local and global time-variant/invariant performance indices. Two sets of deterministic and probabilistic shape optimization algorithms were compared to demonstrate the impact of uncertainty quantification. Finally, the framework is extended to a class of generic dams with different heights, concrete strengths, and foundation-to-concrete flexibility. By probabilistic seismic performance evaluation, system safety is guaranteed using the proposed dynamic RBDO compared to the median response in applying a set of as-recorded ground motions. This paper provides a new paradigm for RBDO of structures with dynamic loading and a robust decision-making during dam design.
•A two-stage adaptive Kriging-assisted quantile-based design optimization is presented.•A stochastic intensifying stressor is coupled with RBDO as dynamic loading.•The ground motion-independent hybrid RBDO is appropriate for real-world applications.•Accuracy is validated using probabilistic seismic safety evaluation.•An approximate data-driven meta-model is proposed for initial design.
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