Engineering Geology最新文献

Extraction of physical quantities such as flow depth and velocities, is one of the major purposes of geophysical flow numerical modeling and critical for estimating consequent impact forces and sediment entrainment. It is simple in nature for mesh-based models but presenting challenges in three-dimensional smoothed particle hydrodynamics (SPH) schemes. The difficulties lie in the substantial number of particles and their uneven spatial-temporal distribution, particularly over complex topography. Inspired by our previous surface cell (SC) -based approach, we propose a novel topography-based and vectorized algorithm that significantly enhances the ability to extract physical quantities over complex topography. In the proposed algorithm, geomorphologic characteristics are mathematically represented by topographical normal vectors. The correlations of physical quantities with distinct coordinate descriptions are established through the vectorization concept, ultimately leading to effective extraction of physical quantities in SPH form over complex topography. This algorithm provides an important tool to incorporate topography-linked physical models within discretized frameworks. To validate its effectiveness, we employed the algorithm to integrate the debris-flow entrainment law with our previous HBP-SPH model, utilizing the 2010 Yohutagawa debris-flow event in Japan as a case study. The results demonstrate a good agreement between the numerical simulation and on-site observation. Discussion regarding the applicability and limitation of the algorithm concludes the paper.

The primary objective of this study was to examine and analyze the sliding behavior of rock wedge slopes with the interaction of three joint sets, considering the influence of plunge angles, included wedge angles between joints, and gravity conditions. The discontinuity planes with varying dip directions relative to the wedge's plunge direction were analyzed. The stability assessment of wedge failure was initially reviewed, explicitly focusing on limit equilibrium (LE) analysis and in-house physical tests. Centrifuge tests and discrete element analysis using the 3DEC software were then performed to explore the factors influencing the failure characteristics of the slopes. Additionally, two mitigation strategies were proposed to enhance the stability of the rock wedge slopes. The key findings include the significant impact of plunge angle on wedge slope stability compared to the included wedge angle between joints, the strong effect of gravitational conditions on the collapsing ratio of wedge units, and the higher risk posed by wedge slopes with discontinuity planes dipping out of the slope. The numerical simulation results highlighted the importance of considering joint spacing in slope stability assessments. Mitigation methods such as fixing key wedge blocks were found to effectively reduce the wedge collapsing ratio and improve rock slope stability under more realistic stress levels. This study provides valuable insights for formulating prevention and mitigation strategies, useful for enhancing safety and reducing the potential damage caused by rock wedge failure events.

The scope of this work was to develop soil liquefaction and landslide hazard maps, by computing Peak Ground Acceleration (PGA) for a return period of 475 years, to outline safe points and escape routes designed for schools situated in the drainage basin of Xerias River at northeastern Peloponnese, Greece. The school locations were spatially correlated with each geohazard map to assess the potential hazards to schools within the study area. Web maps illustrating safe and unsafe areas for both geohazards were developed though the GIS online platform for the town of Corinth and four settlements of the study area, where schools exist. Safe points were identified, and routes for evacuation from schools to these locations were mapped using the shortest paths on the existing road network for each geohazard. All the data was integrated into the GIS application available to the public. The findings indicated that 75% of the schools in the study area are situated in areas susceptible to soil liquefaction and landslide hazards. The northern part of the town of Corinth, which includes 62% of the town's schools, is situated in unsafe areas to soil liquefaction. Unsafe areas for landslides are located in the central and northern section of the town, encompassing 35% of the schools. The school buildings in one settlement within the study area are situated in safe areas for both geohazards. The schools in the remaining settlements are sited in areas considered unsafe due to either liquefaction or landslides hazard. A total of 12 safe points were proposed for soil liquefaction hazard and 17 for landslide hazard across all the studied urban areas. The suggested escape routes for both geohazards range from 200 to 1094 m, distances that teachers and students can easily walk. The proposed method can rapidly and effectively identify safe locations and evacuation routes, facilitating authorities in planning for evacuations.

Rock fracture and rock instability at high temperatures are serious threats to the safe and efficient exploitation of deep geothermal resources. The electric potential (EP) can provide valuable information to monitor and forecast these issues. In this work, compression-shear failure tests were performed to monitor the EPs of granite samples after thermal treatment at 25 °C, 200 °C, 400 °C and 600 °C. The temporal response and non-extensive statistical characteristics of EPs subjected to different thermal treatments were analyzed. The precursory information of the EPs was studied by exploring the change in Tsallis entropy q and variance with the damage variable. The effect of thermal damage on the response mechanisms of EPs was studied using fracture surface scanning, thermogravimetry-infrared radiation (TG-IR) and scanning electron microscopy (SEM) tests. The results show that the thermal treatment affects the EP response by changing the mechanical properties, failure behavior and microstructure. With increasing treatment temperature, the average EP value gradually decreased. The probability density distributions (PDF) of the EPs under different treatment temperatures were consistent with a q-Gaussian distribution, and q increased with increasing treatment temperature. According to the critical theory, the damage state of samples is reflected by the evolution of q and variance based on the EPs and can provide precursory information for instability failure. With increasing treatment temperature, the initial thermal damage becomes more severe, the fractal dimension and roughness of the fracture surface increase, and the unstable propagation of microcracks and precursory points appears earlier.

This study delves into the profound repercussions of geohazards on water supply systems, specifically in the aftermath of the Kahramanmaras earthquakes. The influence of these geohazards was far-reaching, impacting a vast geographical expanse affected by the seismic events. The primary focus of this investigation centers on the provinces of Adiyaman, Gaziantep, and Hatay, providing representative damage examples from the earthquake-affected areas. The study illustrates various types of pipe failures induced by geohazards such as fault displacements, landslides, and liquefaction. The analysis encompasses diverse cases of damage, starting from the water resources, progressing through issues at transmission lines, and extending to challenges faced by pumping and treatment facilities. Key aspects of damages and geohazards are presented, shedding light on the intricate dynamics of these interactions. It is crucial to note the scarcity of real cases in the existing literature, emphasizing the need for extensive site investigations and dedicated research endeavors to construct a comprehensive database of case histories in this domain. This study addresses this gap, contributing valuable insights into the tangible impacts of geohazards on water supply systems. By comprehending and effectively addressing the risks associated with geohazards, water supply organizations can fortify the safety and resilience of their infrastructure. The findings presented herein offer a foundation for informed decision-making and strategic planning, fostering a proactive approach to mitigate potential damages and enhance the overall robustness of water supply systems in regions prone to seismic events and associated geohazards.

The representative elementary volume (REV) of a fractured rock mass is crucial for evaluating the equivalent continuum approach. An innovative computational framework and a harmony dimension method were proposed to estimate and predict the REV, respectively. These methods were applied to a slope along a road. Initially, a high-fidelity 3D discrete fracture network (DFN) was generated using data from unmanned aerial vehicle photogrammetry. Then, the Möller–Trumbore algorithm and Stokes' theorem were extended for fracture intersection analysis and intensity (P₃₂) calculation. Subsequently, an equivalent porous medium model was developed. These components were integrated into a framework to calculate the P₃₂ and equivalent permeability of DFNs of varying sizes, thus determining the optimal REV. Additionally, the harmony dimension method, based on the Levenberg–Marquardt algorithm, was used to predict the relationship between two-dimensional (2D) and 3D DFN properties. This method underwent validation with 10 Poisson processes and 570 percolation simulations. The results show that REV sizes vary with different hydraulic gradients, highlighting the anisotropic nature of 3D fractured media. REV predictions can be made using the variability of 2D parameters. The proposed framework accurately captures geometric and hydraulic behaviors of fractured rock masses with reduced computational cost, while the harmony dimension method simplifies and accelerates prediction. The novel finding of the 2D3D parameter relationship can streamline DFN modeling and analysis.

In acidic environments, rock masses are frequently subjected to severe chemical corrosion, resulting in the initiation of numerous geological engineering disasters. This study aimed to collect physical and mechanical parameters of granite exposed to prolonged acid corrosion and analyze fracture characteristics using acoustic emission (AE) techniques. Additionally, it examined the evolution of pore structure and damage mechanisms through the use of low-field nuclear magnetic resonance (NMR) and fractal theory. The results demonstrate a monotonic decrease in mass, volume, density, P-wave velocity, and S-wave velocity of granite with increasing corrosion time. Particularly notable is the phased reduction observed in uniaxial compressive strength and elastic modulus. The transition from brittle to ductile failure in corroded granite is accompanied by a gradual decrease in internal fracture strength. The trend in the correlation dimension reveals the relationship between the formation time of the main fracture surface and the pore structure. Additionally, total porosity and macropores (D, Da) exhibit significant fractal characteristics. The fractal dimension correlates positively with the damage variable and inversely with uniaxial compressive strength and elastic modulus. This indicates that more severe pore structure damage leads to a higher fractal dimension and lower mechanical performance. Among these, Da demonstrates higher sensitivity in characterizing rock mechanical properties. These findings provide important basis for evaluating the stability of granite geotechnical engineering in acidic environments.

In a complex marine dynamics environment, the consideration of fluid-structure-seabed interaction (FSSI) plays a vital role in reliably analyzing the dynamic response of marine structures, and in assessing their structural dynamic stability. Currently, the predominant numerical analysis used worldwide for the problems of wave-seabed interaction and seawater-structure-seabed interaction is primarily the one-way coupling method. While only a few two-way coupled models are being developed. Consequently, two issues are brought up: (1) For the cases involving small deformation and displacement, the degree of discrepancy can't be quantitatively identified between the results obtained respectively from one-way coupling models and two-way coupled models which are more rigorous in mathematics and physics. (2) For the cases involving large deformation and displacement, one-way coupling models should be non-applicable. To address this problem, this study first proposes an explicit two-way coupling theory for the fluid-structure-seabed interaction. Then, a two-way coupled numerical model is developed by integrating the soil-structure dynamics software FssiCAS, and an OpenFOAM-based CFD solver OlaFlow by utilizing the data exchange library preCICE. This two-way coupled model has been embedded into the software FssiCAS. The reliability of the developed two-way coupled model is systematically validated through a rigorous verification process. Subsequently, a comparative study is conducted between the newly developed two-way coupled model and the existing one-way coupling model, to investigate the ocean wave-seabed interaction, as well as the interaction process between ocean wave, a breakwater, and seabed foundation. A comprehensive analysis is performed by comparing the differences in the wave profiles in fluid domain, dynamic displacement of structure and seabed foundation, seepage, pore pressure accumulation, and liquefaction in seabed foundation solved by the two-way and one-way coupled models. Finally, the suitability of the one-way and two-way coupled models in different applicable scenarios was discussed.

Rockburst exhibits different occurrence time characteristics during drilling and blasting in tunnel excavation, posing challenges to the safe and efficient construction of tunnels. In this study, 25 tunnels with rockburst hazards were examined. By employing the clustering method, we analyzed the characteristics of the most prone time (MPT) for rockburst. Furthermore, we investigated the contribution degree and influence mechanism of stress and geological factors related to the MPT of rockburst. The outcomes revealed that distinct tunnels exhibit diverse rockburst-prone times, leading to varying hazards and losses. The higher the maximum principal stress and the angle between it and the tunnel axis, the earlier the rockburst occurs. Moreover, the MPT of rockburst is influenced by both lithological types, macro and micro rock structures. When the joint intersects with the maximum principal stress at a small angle, rockburst occurs earlier. The stress direction, UCS, attitude of the dominant joint, and stress magnitude stand out as the principal controlling factors. The findings of this research can serve as a basis for assessing the MPT of tunnel rockburst, timing rockburst risk control measures, and selecting appropriate mitigation strategies.

To investigate the effects of traffic loads on frost heave behaviors, frost heave tests of silty clay soil were conducted using an improved temperature-controlled cyclic compression-shear device. This research employed three stress modes: vertical cyclic stress, horizontal cyclic shear stress, and complex cyclic stress that combines vertical cyclic stress with horizontal cyclic shear stress. Additionally, it considered the effects of the amplitude and frequency of complex cyclic stress. Test results show vertical cyclic stress densifies specimens and restrains vertical displacement development. Vertical cyclic stress's pumping effect promotes water absorption during frost heave. Horizontal cyclic shear stress can increase in-situ frost heave and induce minor consolidation than vertical cyclic stress, dramatically enhancing vertical displacement. Under complex cyclic stress conditions, vertical cyclic stress and horizontal cyclic shear stress at low amplitudes and frequencies enhance vertical displacement. The primary component that promotes the frost heave ratio is horizontal cyclic shear stress, which could lead to a looser frozen soil structure. Finally, an improved frost heave ratio prediction model was developed, considering the influences of vertical cyclic stress, horizontal cyclic shear stress, and loading frequency.