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The two crucial shape factors (elongation ratio and flatness ratio) of brittle particles may influence the dynamic breakage of brittle particles upon impact. Hence, three‐dimensional discrete element method simulations of brittle rock blocks with different shapes upon normal impact were performed. The simulated results indicate that the elongation ratio, that is, ratio of width to length and flatness ratio, that is, ratio of thickness to width can significantly affect the breakage of brittle rock blocks. Three fracture mechanisms, that is, fragmentation, horizontal tensile fracture and vertical tensile fracture, were revealed, which determine the dynamic breakage of rock blocks. The fragmentation results in numerous single‐sphered fragments with velocities even larger than 2 times of the initial velocities. Fragmentation can provide a buffering effect at high impact velocities of larger than 4 m/s. With an increasing elongation ratio or flatness ratio, the phenomenon of fragmentation gradually disappears. The reflection of a compression stress wave results in horizontal tensile fracture. The expansion in the plane perpendicular to the impact velocity results in vertical tensile fracture. [ABSTRACT FROM AUTHOR]

The accurate assessment of hydraulic transmissivity in rock fractures filled with particles is not only a scientific challenge but also a critical need for various industrial applications. However, the intricate dynamics of particle erosion and pore clogging that govern transmissivity evolution remain largely unexplored. In this study, we experimentally examine the fluid‐driven particle migration behavior in filled fractures and its consequent impact on fracture transmissivity under various hydraulic gradients, normal stresses, and fracture apertures. We find that escalating hydraulic gradients not only intensify particle erosion through amplified fluid drag forces and hydro‐mechanical coupling effects but also lead to an increase in the size of migrating particles, thereby augmenting pore clogging. The dynamics of erosion and clogging define four distinct migration phases within the filled fractures. Variations in normal stress and initial fracture aperture significantly alter the particle arrangement and the soil structure stability within the fractures, thereby modulating the progress of particle migration in response to hydraulic gradients. The pattern of particle migration in filled fractures dictates the development of the internal pore structure and normal deformation, ultimately affecting fracture transmissivity. We propose an empirical expression to encapsulate the comprehensive evolution of fracture transmissivity across different particle migration patterns. Our research advances the understanding of fluid‐driven particle migration within filled fractures and provides a practical tool for the precise determination of hydraulic properties of fractured rocks amidst complex geological settings. Plain Language Summary: Filled fractures in rock masses, serving as dominant flow channels and potential failure planes, are typically perceived to exhibit constant hydraulic transmissivity. However, this perspective oversimplifies the dynamic nature of filled fractures, where fluid flow can greatly change the hydraulic characteristics by either eroding or accumulating the internal particles. Understanding how these filling particles respond to water flow and affect fracture transmissivity is vital for many geological processes and human activities. Here, we experimentally uncover four distinct phases of particle migration within a filled fracture, instigated by the dynamics of erosion and clogging under elevated hydraulic gradients. Variations in normal stress and fracture aperture significantly influence the particle arrangement and the soil structure stability within fractures, thereby affecting particle migration characteristics across phases. On this basis, we delve into how the patterns of particle migration impact the geometric structure of the filled fracture and, thus, the fracture transmissivity. Finally, we quantitatively portray the evolution in fracture transmissivity across various particle migration scenarios using an empirical model. Our findings enhance the understanding of fluid‐driven particle migration in filled fractures and provide a path forward for accurately assessing the hydraulic properties of fractured rocks in complex geological environments. Key Points: Erosion and clogging dynamics, modulated by hydraulic gradients, define four particle migration phases in stressed‐filled fracturesParticle migration patterns dictate pore structure and normal deformation, impacting fracture transmissivityAn empirical model encapsulates fracture transmissivity evolution across different particle migration patterns [ABSTRACT FROM AUTHOR]

Summary: Though the technology of using stabilizing piles to prevent landsliding is not new, the design of such piles with a meaningful optimization framework has been rarely reported. In this paper, a multiobjective optimization‐based framework for design of stabilizing piles is presented, in which both reinforcement effectiveness and cost efficiency could be explicitly considered. The design parameters considered in the proposed design framework are the pile parameters, including pile diameter, spacing, length, and position, and the design objectives considered are the reinforcement effectiveness and cost efficiency. The design of stabilizing piles is then implemented as a multiobjective optimization problem. In that the desire to maximize the reinforcement effectiveness and that to maximize the cost efficiency are two conflicting objectives, the output of this multiobjective optimization will be a Pareto front that depicts a trade‐off between these two design objectives. With the obtained Pareto front, an informed decision regarding the design of stabilizing piles is reached. The effectiveness and significance of the proposed multiobjective optimization‐based design framework for stabilizing piles are demonstrated through two illustrative examples: one is the design of stabilizing piles in a one‐layer earth slope and the other the design of stabilizing piles in a two‐layer earth slope. Further, parametric analyses are conducted to investigate the influences of the pile design parameters on the stability of reinforced slopes. [ABSTRACT FROM AUTHOR]