The current investigation examines the fluctuating behaviour of stiff pavement built on a two-parameter base and is influenced by aircraft loading impacts. This investigation is driven by the necessity for an accurate evaluation of pavement behaviour under elevated stress scenarios caused by aircraft, which can guide pavement design and upkeep. A stochastic numerical model, the vehicle-pavement interaction model (VPI), was created using a comprehensive 3D dynamic model of an aircraft vehicle and stationary runway roughness profiles. The rigid pavement is simulated using a computationally efficient 1D finite element mathematical model incorporating six DOF. The Pasternak model represents the soil medium, incorporating shear interaction between the spring elements. The pavement's irregularities are considered and replicated using a power spectral density (PSD) function. This assembled model was used to investigate the dynamical reaction of concrete pavement vibrations caused by the passing of an aircraft vehicle using MATLAB code. The dynamic governing differential equations of the aircraft's motion are developed and coupled with the pavement system equations. The coupled system is then solved in the time domain using the direct computational integration approach with the Newmark-Beta integration scheme, explicitly utilizing the linear average acceleration method. This approach is employed to resolve the equations that govern and assess the performance of the connected system. The current findings are being compared to existing analytical outcomes to verify the precision of the current coding. The research examined the impact of various pavement and aircraft vehicle behaviors and factors on the dynamic response of pavement, including the speed, main and auxiliary suspension components, mass and the load position of the aircraft, also the damping, random roughness, thickness, span length and elastic constant of the pavement, even, the modulus of subgrade of the foundation, the rigidity modulus of the shear layer. The findings demonstrate notable influences of aircraft speed and pavement surface roughness on various response parameters. Specifically, the results reveal that a higher subgrade modulus leads to decreased deflection, rotation, and bending moments. Conversely, longer span lengths tend to elevate response parameters while simultaneously reducing shear force. In conclusion, the results highlight the significance of critical factors, including velocity and subgrade modulus, in forecasting the performance of pavement subjected to aircraft loads. The present research is confined to the investigation of the dynamic's performance of the VPI simulation of airfield rigid pavement. The findings from this study can be expanded on by paving engineers to improve the structural effectiveness and reliability of the pavement, serving as a basis for subsequent fatigue analysis in response to diverse dynamic loads such as earthquake, temperature and vehicle load.

An appropriate interface constitutive model is crucial to the simulation of soil-structure interface behavior. Currently, most models are only capable of describing the mechanical properties of rough interface. However, they are unable to simultaneously account for the effects of surface roughness and particle breakage. This study proposes an elastoplastic interface constitutive model considering the effects of normal stress, relative density, particle breakage, and surface roughness. It describes the variations of critical void ratio and critical stress ratio with normalized surface roughness by exponential functions. Change in critical void ratio caused by particle breakage is denoted by input work. An expression of the critical state line and a modified dilatancy function are derived based on the state-dependent dilatancy theory, uniformly describing the influences of relative density, particle breakage, normal stress, and surface roughness. The yield and hardening functions are introduced by including the plastic shear displacement as the hardening parameter based on the Mohr-Coulomb criterion. Finally, experimental data from the literature are utilized to validate the accuracy of the proposed model for various materials under different conditions.

This study aims to systematically investigate the influence mechanism of particle size and surface roughness on the shear mechanical behavior of spherical particle materials. Rough glass beads with different particle sizes (2 mm, 3 mm, 4 mm) were prepared using sandblasting technique. Together with smooth glass beads, they were used as test raw materials for indoor triaxial consolidated-drained (CD) tests. Based on the quantitative characterization of particle surface roughness, the differences in the shear mechanical properties of spherical particle materials, including stress-strain curves, strength parameters, critical state characteristics, and stick-slip behavior, etc., were discussed from the aspects of the particle size effect (R), the surface roughness index (Ra), and the normalized roughness effect (Ra/R). The main research results show that: increasing the surface roughness of particles can improve various shear mechanical parameters to a certain extent. This includes effectively increasing the peak deviatoric stress, expanding the range of the strength envelope, and raising the deviatoric stress corresponding to the specimen in the critical failure state. It can significantly increase the peak friction angle phi by approximately 10 %-40 % and the critical state line slope (CSL slope) by about 5 %-23 %. Moreover, the increase becomes more pronounced as the particle size decreases. Meanwhile, as the normalized roughness effect (Ra/R) increases, the friction coefficient becomes larger, which greatly weakens the stick-slip behavior between particles.

The joint roughness coefficient (JRC) is a key parameter in the assessment of mechanical properties and the stability of rock masses. This paper presents a novel approach to JRC evaluation using a genetic algorithm-optimized backpropagation (GA-BP) neural network. Conventional JRC evaluations have typically depended on two-dimensional (2D) and three-dimensional (3D) parameter calculation methods, which fail to fully capture the nonlinear relationship between the complex surface morphology of joints and their roughness. Our analysis from shear tests on eight different joint types revealed that the strength and failure characteristics of the joints not only exhibit directional dependence but also positively correlate with surface dip angles, heights, and back slope morphological features. Subsequently, five simple statistical parameters, i.e. average dip angle, median dip angle, average height, height coefficient of variation, and back slope feature value (K), were utilized to quantify these characteristics. For the prediction of JRC, we compiled and analyzed 105 datasets, each containing these five statistical parameters and their corresponding JRC values. A GA-BP neural network model was then constructed using this dataset, with the five morphological characteristic statistics serving as inputs and the JRC values as outputs. A comparative analysis was performed between the GA-BP neural network model, the statistical parameter method, and the fractal parameter method. This analysis confirmed that our proposed method offers higher accuracy in evaluating the roughness coefficient and shear strength of joints. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Understanding the shear mechanical behaviors and instability mechanisms of rock joints under dynamic loading remains a complex challenge. This research conducts a series of direct shear tests on real rock joints subjected to cyclic normal loads to assess the influence of dynamic normal loading amplitude (Fd), dynamic normal loading frequency (fv), initial normal loading (Fs), and the joint roughness coefficient (JRC) on the mechanical properties and instability responses of these joints. The results show that unstable sliding is often accompanied by friction weakening due to dynamic normal loads. A significant negative correlation exists between cyclic normal loads and the normal displacement during the shearing process. Dynamic normal load paths vary the contact states of asperities on the rough joint surfaces, impacting the stick-slip instability mechanism of the joints, which in turn affects both the magnitude and location of the stress drop during the stick-slip events, particularly during the unloading phases. An increasing Fd results in a more stable shearing behavior and a reduction in the amplitude of stick-slip stress drops. The variation in fv influences the amplitude of stress drop for the joints during shear, characterized by an initial decrease (fv = 0.25-2 Hz) before exhibiting an increment (fv = 2-4 Hz). As Fs increases, sudden failures of the interlocked rough surfaces are more prone to occur, thus producing enhanced instability and a more substantial stress drop. Additionally, a larger JRC intensifies the instability of the joints, which would induce a more pronounced decline in the stick-slip stress. The Rate and state friction (RSF) law can provide an effective explanation for the unstable sliding phenomena of joints during the oscillations of normal loads. The findings may provide certain useful references for a deeper comprehension of the sliding behaviors exhibited by rock joints when subjected to cyclic dynamic disturbances. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Flash floods are highly destructive natural disasters, particularly in arid and semi-arid regions like Egypt, where data scarcity poses significant challenges for analysis. This study focuses on the Wadi Al-Barud basin in Egypt's Central Eastern Desert (CED), where a severe flash flood occurred on 26-27 October 2016. This flash flood event, characterized by moderate rainfall (16.4 mm/day) and a total volume of 8.85 x 106 m3, caused minor infrastructure damage, with 78.4% of the rainfall occurring within 6 h. A significant portion of floodwaters was stored in dam reservoirs, reducing downstream impacts. Multi-source data, including Landsat 8 OLI imagery, ALOS-PALSAR radar data, Global Precipitation Measurements-Integrated Multi-satellite Retrievals for Final Run (GPM-FR) precipitation data, geologic maps, field measurements, and Triangulated Irregular Networks (TINs), were integrated to analyze the flash flood event. The Soil Conservation Service Curve Number (SCS-CN) method integrated with several hydrologic models, including the Hydrologic Modelling System (HEC-HMS), Soil and Water Assessment Tool (SWAT), and European Hydrological System Model (MIKE-SHE), was applied to evaluate flood forecasting, watershed management, and runoff estimation, with results cross-validated using TIN-derived DEMs, field measurements, and Landsat 8 imagery. The SCS-CN method proved effective, with percentage differences of 5.4% and 11.7% for reservoirs 1 and 3, respectively. High-resolution GPM-FR rainfall data and ALOS-derived soil texture mapping were particularly valuable for flash flood analysis in data-scarce regions. The study concluded that the existing protection plan is sufficient for 25- and 50-year return periods but inadequate for 100-year events, especially under climate change. Recommendations include constructing additional reservoirs (0.25 x 106 m3 and 1 x 106 m3) along Wadi Kahlah and Al-Barud Delta, reinforcing the Safaga-Qena highway, and building protective barriers to divert floodwaters. The methodology is applicable to similar flash flood events globally, and advancements in geomatics and datasets will enhance future flood prediction and management.

The critical normalized roughness (Rcr) serves as a pivotal metric for distinguishing the roughness of the soil-- structure interface. The accurate determination of Rcr is highly important in both research and engineering applications related to the mechanical properties of the interface. However, research on methods for determining Rcr are scare, and the theoretical methods are especially rare. This paper aims to establish a theoretical calculation method of critical normalized roughness Rcr. Using tribology theory, the existence of Rcr was corroborated through the analysis of both single-particle sliding and whole-soil sliding mechanisms. A theoretical formula was subsequently established for the computation of Rcr. A comparison between the theoretical calculations and experimental results revealed that the proposed formula is applicable to both scenarios involving particle breakage and scenarios lacking particle breakage at the interface. Compared with scenarios without particle breakage, the theoretical formula exhibits a superior predictive capacity for cases involving particle breakage. The proposed theoretical calculation method in this paper provides a novel approach and perspective for determining the critical normalized roughness Rcr.

The mineralogy and texture of granite have been found to have a pronounced effect on its mechanical behavior. However, the precise manner in which the texture of granite affects the shear behavior of fractures remains enigmatic. In this study, fine-grained granite (FG) and coarse-grained granite (CG) were used to create tensile fractures with surface roughness (i.e. joint roughness coefficient (JRC)) within the range of 5.48-8.34 and 12.68-16.5, respectively. The pre-fractured specimens were then subjected to direct shear tests under normal stresses of 1-30 MPa. The results reveal that shear strengths are smaller and stick-slip behaviors are more intense for FG fractures than for CG fractures, which is attributed to the different conditions of the shear surface constrained by the grain size. The smaller grain size in FG contributes to the smoother fracture surface and lower shear strength. The negative friction rate parameter a - b for both CG and FG fractures and the larger shear stiffness for FG than for CG fractures can account for the more intense stick-slip behaviors in FG fractures. The relative crack density for the post-shear CG fractures is greater than that of the FG fractures under the same normal stress, both of which decrease with the distance away from the shear surface following the power law. Moreover, the damage of CG fracture extends to a larger extent beneath the surface compared with the FG fracture. Our findings demonstrate that the grain size of the host rock exerts a significant influence on the fracture roughness, and thus should be incorporated into the assessment of fault slip behavior to better understand the role of mineralogy and texture in seismic activities. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

The roughness of the fracture surface directly affects the strength, deformation, and permeability of the surrounding rock in deep underground engineering. Understanding the effect of high temperature and thermal cycle on the fracture surface roughness plays an important role in estimating the damage degree and stability of deep rock mass. In this paper, the variations of fracture surface roughness of granite after different heating and thermal cycles were investigated using the joint roughness coefficient method (JRC), three-dimensional (3D) roughness parameters, and fractal dimension (D), and the mechanism of damage and deterioration of granite were revealed. The experimental results show an increase in the roughness of the granite fracture surface as temperature and cycle number were incremented. The variations of JRC, height parameter, inclination parameter and area parameter with the temperature conformed to the Boltzmann's functional distribution, while the D decreased linearly as the temperature increased. Besides, the anisotropy index (I-p) of the granite fracture surface increased as the temperature increased, and the larger parameter values of roughness characterization at different temperatures were attained mainly in directions of 20 degrees-40 degrees, 60 degrees-100 degrees and 140 degrees-160 degrees. The fracture aperture of granite after fracture followed the Gauss distribution and the average aperture increased with increasing temperature, which increased from 0.665 mm at 25 degrees C to 1.058 mm at 800 degrees C. High temperature caused an uneven thermal expansion, water evaporation, and oxidation of minerals within the granite, which promoted the growth and expansion of microfractures, and reduced interparticle bonding strength. In particular, the damage was exacerbated by the expansion and cracking of the quartz phase transition after T > 500 degrees C. Thermal cycles contributed to the accumulation of this damage and further weakened the interparticle bonding forces, resulting in a significant increase in the roughness, anisotropy, and aperture of the fracture surface after five cycles. (c) 2025 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/ 4.0/).

Understanding the interface shear behavior between clay and structures is crucial in geotechnical engineering. The mechanism of the roughness effect in the shear process between the clay and structures was studied to reveal the macroscopic and microscopic interface shear behavior. The different surface protrusion shapes of the structures were produced using a three-dimensional (3D) printer. Direct shear tests were conducted to analyze the shear failure modes and peak and residual strengths under different conditions. Subsequently, a discrete element method (DEM) numerical analysis was employed to study the contact network, soil fabric evolution, shear zone, coordination number, and void ratio variations in the interface shear. The test results indicated that the shear interfaces exhibited the same failure mode under various conditions, and the peak and residual strengths showed a strong positive correlation with roughness. The results obtained from numerical calculations match the experimental findings. The contact orientations and principal stresses shifted during the shear process, and the shear zone, coordination number, and void ratio also showed regular changes with the change of roughness. The evolution of microscopic parameters in DEM can effectively help explain the macroscopic interface shear behavior.