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High concrete gravity dams, particularly Roller-Compacted Concrete (RCC) types, face long-term safety challenges due to weak interlayer formation and crack propagation. This study presented a comprehensive evaluation of safety monitoring indexes for the Guxian high RCC dam (currently under construction) using both numerical and mathematical models. A finite element method (FEM) is employed with a strength reduction approach to assess dam stability considering weak layers. In parallel, a fracture mechanical model is used to investigate the safety of the Guxian dam based on failure assessment diagrams (FADs) for calculating the safety factor and the residual strength curve for calculating critical crack depth for two different crack locations, single-edge and center-through crack, to investigate the high possible risk associated with crack location on the dam safety. Additionally, the Guxian dam’s resistance to hydraulic fracture is assessed under two fracture mechanic failure modes, Mode I (open type) and Mode II (in-plane shear), by computing the ultimate overload coefficient using a proposed novel derived formula. The results show that weak layers reduce the dam’s safety index by approximately 20%, especially in lower sections with extensive interfaces. Single-edge cracks pose greater risk, decreasing the safety factor by 10% and reducing critical crack depth by 40% compared to center cracks. Mode II demonstrates higher resistance to hydraulic fracture due to greater shear strength and fracture energy, whereas Mode I represents the most critical failure scenario. The findings highlight the urgent need to incorporate weak layer behavior and hydraulic fracture mechanisms into dam safety monitoring, and to design regulations for high RCC gravity dams.

In order to adapt to the development of automated dam monitoring systems, artificial intelligence (AI) models based on deep learning are used for dam deformation prediction, effectively overcoming the limitations of traditional statistical analysis methods. These AI models have demonstrated excellent performance in capturing the deformation characteristics and potential dependencies of dams during their long-term service. This study takes a certain rolled concrete gravity dam as an object and combines the dam deformation statistical model with the Informer deep learning model to propose an attention mechanism dam deformation prediction model that considers water pressure, temperature, and aging factors. The comparative analysis of model performance indicates that, compared with commonly used models, such as multiple linear regression, support vector machines, and long short-term memory neural networks, the proposed model can better adapt to the complex nonlinear relationship between dam deformation and influencing factors and has excellent predictive performance and generalization ability, effectively improving the accuracy of dam deformation prediction and providing practical engineering benefits for dam safety monitoring.

Deformation can directly reflect the working behavior of the dam, so determining the deformation monitoring control value can effectively monitor the safety of dam operation. The traditional dam deformation monitoring control value only considers the single measuring point. In order to overcome the limitation, this paper presents a new method to determine the monitoring control value for concrete gravity dam based on the deformations of multi-measuring points. A dam’s comprehensive deformation displacement is determined by the measured values at different measuring points on the positive inverted vertical line and the corresponding weight of each measuring point. The projection pursuit method (PPM) combined with the grey wolf optimization (GWO) algorithm is used to determine the weight of each measuring point according to the spatial correlation distribution characteristics of dam deformation. The peaks over threshold (POT) model based on the extreme value theory is adopted to determine the monitoring control value with the obtained dam comprehensive deformation displacement. In addition, the POT model is improved with the automatic threshold determination method based on the criterion in probability theory and the GWO algorithm, which can avoid subjectivity and randomness in determining the threshold. The results of the engineering application show the feasibility and applicability of the proposed method.

Cracks are always a serious concern in the stability analysis of gravity dams. One of the main reasons for the initiation of cracks is overflow. In most previous crack propagation analyses, the presence of water and different configuration of the materials is not considered. In this study, to adequately evaluate the crack development in gravity dams subjected to overflow, a polygonal grain-based model (P-GBM), enriched in considering the influence of joint roughness through the Barton–Bandis (B-B) model, is employed in a distinct element framework. To take into account the effect of joint softening on the tensile strength of cracks, the B-B model is improved by a polynomial tensile law. Then, the model is verified by Brazilian and Uniaxial tests containing various combinations of rock and mortar. The numerical results demonstrated a good agreement by the experiments in terms of the strength characteristics and fracture phenomenon. Then, failure analysis for two heterogeneous gravity dams with various complexities under the reservoir overflow is investigated. Performing the risk analysis with different flood scenarios revealed that because of considering the joint–water interactions, the P-GBM suitably predicts the crack propagation. The crack path begins nearly horizontal and then turns downwards toward the dam’s toe. Once cracks form, they act as conduits for water movement and allow more water to penetrate, which increases the pore water pressure and accelerates the propagation of cracks. Also, the critical dam displacements in terms of cracking (initiation, horizontal, and inclined parts) are investigated with different approaches, such as the tangent intersection method, the external second-order work, and the broken joint index. The results revealed that all three techniques determine suitably the critical heights and horizontal displacements in various flood scenarios.HighlightsThe polygonal grain-based technique simulates the rock and mortar combinations in good agreement with experimental tests.The improved Barton–Bandis joint model for softening can reasonably predict the tension behavior of materials.The impact of water on the dam structure and inside the cracks during an overflow is assessed for two case studies by a distinct element method.For a 6 m overtopping, the cracks develop inside the dam body horizontally parallel to the crest. For a 12 m overtopping, the cracks extend to the downstream direction of the dam, and the dam body is severely damaged.

There is an increasing concern on the vulnerability of concrete gravity dams under blast loads. To a better evaluation of the blast-resistance, the effect of the initial stress field is taken into consideration herein. Firstly, a fluid-solid coupling numerical model is established to investigate the blast-resistance of concrete gravity dams. The numerical results indicate that the initial stress field has non-neglectable effect on the shock wave propagation, blast vibration, and failure mode of concrete gravity dams. The damage of dam base may be overestimated without the consideration of initial stress field. Moreover, a parametric study are carried out for further investigations of the dynamic responses and damage properties under various explosion scenarios (explosive charge, detonation depth, and standoff distance). With the consideration of the initial stress field, it can be concluded that the dam head nearest the explosive source is the weakest part, and the safety of the dam base is another important consideration, which may lead to severe dam-break floods. At last, a new method is proposed and recommended to evaluate the blast resistance of the whole concrete gravity dam, where the blast-induced vibration and penetration depth of cracks are suggested for the dam crest and dam base, respectively.

The shear strength of the concrete–rock interface has a substantial influence on the sliding stability of concrete gravity dams founded on rock. While several studies have been done on concrete–rock contacts, there remains uncertainty regarding the peak shear strength of partially bonded interfaces. There exists, in particular, an uncertainty regarding the contribution from surface roughness of the unbonded parts to the peak shear strength of the interface due to the dependency of mobilized strength on shear displacement. In this study, a series of 24 direct shear tests are performed under CNL conditions on concrete–rock samples with different bonding conditions. Tests on samples with fully bonded and unbonded interfaces are conducted to study the strain compatibility of the different contacts, while the results of samples with partially bonded interfaces are evaluated in the context of linking the joint roughness of the unbonded parts to the peak shear strength of the interface. The results indicate that a significant part of the surface roughness of the unbonded parts is mobilized prior to degradation of bond strength, in particular for interfaces with low bonding percentages. It is recommended that further research should be conducted to understand how the contribution from roughness change with an increase in scale and degree of matedness.

To address the challenge that traditional dam model materials are difficult to simultaneously meet the requirements of microstructural similarity, dynamic damage simulation, and environmental friendliness, a novel microparticle mortar simulated concrete was developed. This new material consists of cement, sand, gypsum, mineral oil, water, and baryte sand. Through systematic material mechanical tests, the effects of each component on the material’s strength, density, and elastic modulus were revealed, and the optimal mix ratio was determined. This enabled precise control of low elastic modulus and had a high density, while the material is environmentally friendly, non-toxic, and compatible with direct contact with natural water. Its mechanical properties are highly similar to those of the prototype concrete. Based on a 1:70 geometric scale, a shaking table model test of the concrete gravity dam-reservoir system was conducted. The dynamic response and damage evolution under empty and full reservoir conditions were compared and analyzed. The study shows that this material can accurately simulate the stress-strain relationship and failure mode of prototype concrete. Under the full reservoir condition, the dam’s fundamental frequency showed only a 2.72% deviation from the numerical simulation, and as the seismic excitation amplitude increased, the changes in the fundamental frequency effectively reflected the accumulation of damage. Under the design seismic motion, the measured accelerations and stress responses for both empty and full reservoir conditions were in good agreement with numerical calculations. Under overload conditions, the acceleration amplification factor at the dam crest decreased with damage accumulation, and the dam neck was identified as the seismic weak zone. As the peak ground acceleration (PGA) increased from 0.15 g to 0.70 g, the fundamental frequency changes effectively reflected the damage accumulation process in the dam, while the hydrodynamic pressure at the dam heel showed a linear increase (457% increase). The experimentally measured hydrodynamic pressure distribution was between the rigid dam and elastic dam hydrodynamic pressures, reflecting the real fluid-structure interaction effect. This study provides a reliable material solution and data support for dam seismic physical model testing.

Owing to the insufficient understanding of the mechanical properties and damage mechanisms of concrete-rock bonding interfaces in dam foundations, this study establishes a refined three-dimensional simulation model for direct shear tests of concrete-rock bonding interfaces based on in-situ direct shear tests conducted at a reservoir. The damage evolution process and failure mechanisms of the concrete-rock interface under different loading conditions are investigated. The results indicate that under varying normal stresses, the shear stress-shear displacement curve exhibits an initial increase followed by a gradual decrease, with peak shear strength ranging from 1.074 MPa to 2.073 MPa and a maximum error of 8.48%, meeting engineering requirements. The damage evolution process of the concrete-rock interface under different normal forces was simulated and compared with in-situ direct shear test results, confirming the accuracy of the simulation. The failure modes of the concrete-rock interface under different loading conditions can be categorized into three types: bonding interface failure, mixed shear failure, and rock failure. The failure mode is closely related to the magnitude of normal stress—as normal stress increases, the area of shear fracture along the bonding interface expands, and the fracture surface becomes smoother. The findings provide a theoretical basis for the design, anti-sliding stability, and risk analysis of similar concrete gravity dams.

The article deals with the issues of improving hydraulic retain-ing structures of the gravity (massive) type. In order to reduce the cost of building gravity (massive) dams and increase their efficiency, a constant search for new, more efficient design solutions is underway. The purpose of the research is to analyze the main directions of improving hydraulic re-taining structures of gravity type. The article suggests a more effective method for improving concrete gravity dams, based on the idealization of structural and technological solutions. Its peculiarity is that on the basis of the identified solutions of the traditional method, an effective design of a concrete dam and the technology of its construction are selected, and then promising, patentable solutions are developed, which in their properties approach the ideal structures. In accordance with the method, the structural and technological solutions of the gravity dam with the use of coarse-pored concrete were developed. The design is high-tech and allows cooling of the dam mass by filtering water through large pores of concrete.

For the safety assessment of concrete dam–foundation systems, this study used an explicit time-stepping small-displacement algorithm, which simulates the hydromechanical interaction and considers the discrete representation of the foundation discontinuities. The proposed innovative methodology allows for the definition of more reliable safety factors and the identification of more realistic failure modes by integrating (i) softening-based constitutive laws that are closer to the real behavior identified experimentally in concrete–concrete and concrete–rock interfaces; (ii) a water height increase that can be considered in both hydraulic and mechanical models; and (iii) fracture propagation along the dam–foundation interface. Parametric studies were conducted to assess the impact of the mechanical properties on the global safety factors of three gravity dams with different heights. The results obtained using a coupled/fracture propagation model were compared with those from the strength reduction method and the overtopping scenario not considering the hydraulic pressure increase. The results show that the safety assessment should be conducted using the proposed methodology. It is shown that the concrete–rock interface should preferably have a high value of fracture energy or, ideally, higher tensile and cohesion strengths and high associated fracture energy. The results also indicate that with a brittle concrete–rock model, the predicted safety factors are always conservative when compared with those that consider the fracture energy.