Due to the time-dependent effect of rockfill dams, the conventional time-invariant finite element method (FEM) can hardly meet practical engineering requirements. This paper proposes an updating Bayesian FEM method for accurate long-term deformation analysis. A combined FEM model is introduced accounting for both instantaneous and creep behaviors. The FEM model is then updated using a Bayesian algorithm, unscented Kalman filter (UKF). The UKF calibrates the prior FEM predictions by incorporating real-time measurement data, thus iteratively reducing discrepancies between model predictions and actual observations. To further enhance the algorithm accuracy, a power-law-based fading memory factor is proposed to mitigate measurement noise in standard UKF. For parameter identification, a slice approach of the high-dimensional covariance confidence ellipsoid is developed. The methodology is validated in Qingyuan rockfill dam, in Guangdong province, China. Results show that the updated FEM is more consistent with the actual monitoring data. The fading memory improves standard UKF performance with a lower relative root-mean-square error (RRMSE). Additionally, the slice method reveals that a specific three-parameter configuration behaves better than the others. The proposed approach can also be extended to other fields including slope and tunneling.

The long initial and coda waves with small amplitude are often observed in an actual earthquake record. Truncating those wavebands that contribute little to structural responses is helpful to focus on the strong shaking phase and reduce computational cost. In the paper, 157 actual earthquake records and the acceleration time windows constrained by truncation thresholds of Arias intensity serve as input ground motions. A large number of elastoplastic dynamic analyses on a 295 m-high core-wall rockfill dam (CRFD) are conducted using the generalized plasticity model and seismic wave input method. Inspired by fragility equation, the probability curves for the accuracy loss of dam response less than different limits under different truncation thresholds are established, quantifying the destructiveness of the truncated seismic acceleration time windows. Results show that the probabilities are minimally affected by peak ground acceleration (PGA); the allowable tail truncation of earthquake records is much more than the leading due to the asymmetry of seismic waveforms and the cyclic hardening characteristic of rockfill materials; the truncation metric of 0.01-98 % Arias intensity is proved to be effective and robust in accelerating dynamic analyses of rockfill dams with an accuracy loss within 5 % and an average reduction in computational workload of approximately 50 %.

With the frequent occurrence of natural disasters, the problem of dam failure with low probability and high risk has gradually attracted people's attention. This paper uses flume model tests to systematically analyze the overtopping failure mechanisms of concrete face rockfill dam (CFRD) and identify its failure modes. The tests reveal that the longitudinal erosion of the CFRD breach progress through stages of soil erosion, panel failures, and water flow stabilization. Meanwhile, the cross- breach process involves the evolution of breach size in rockfill materials, including traceable erosion, lateral broadening, and breach morphology stabilization. The fracture characteristics of the water-blocking panel are primarily evident in the flow-time curve. By analyzing the breach morphology evolution processes in longitudinal and cross sections, the flowtime curve can be subdivided into stages of burst flow formation, breach expansion with flow increase, rapid increase of breach flow discharge due to panel failures, and stabilization of breach flow and size. The primary damage process of the CFRD occurs in a cyclical stage of breach expansion, flow increase, panel failure, and rapid discharge. The rigid face plate and granular body structure contribute to partial dam failure, showing a tendency for gradual expansion of the breach. The longitudinal illustrates dam failure resulting from panel fracture and rockfill erosion interaction, while downstream slopes exhibit failure due to lateral intrusion of rockfill and cyclic instability. These research results can serve as a reference for constructing a concrete CFRD failure prediction model and conducting disaster risk assessments.

During the construction of earth-rock dams in cold regions, the freezing-thawing of impervious soil causes significant changes in its physical and mechanical properties, which affects the quality and operation safety of the project. To enhance the impervious soil anti-freezing capacity, the hollow polycarbonate panel heating method (HPPHM) was innovatively proposed. Based on the mechanism and in-situ tests, the heating mechanism and effect of HPPHM on impervious soil were investigated. The test results indicated that HPPHM can primarily heat the soil through solar radiation, raising the soil temperature. Furthermore, the air layer inside the panel serves as thermal insulation, effectively preventing the soil internal heat from dissipating. The in-situ test results showed that soil freezing was not observed under HPPHM, and the soil surface temperature was approximately 6 degrees C higher compared to the control site. The heating influence depth of HPPHM on the impervious soil was approximately 175 cm. Additionally, the soil heat under HPPHM experienced a significant increase of 12537.1 kJ. This study provides a scientific method for improving construction efficiency and quality in cold regions.