Search Results (42)

Rainfall can easily cause local sliding and collapse of carbonaceous mudstone deep road cut slopes. In order to study the strength characteristics of carbonaceous mudstone under different water environments, large-scale horizontal push shear tests were conducted on carbonaceous mudstone rock masses in their natural state and after immersion in saturated water. The push shear force–displacement relationship curve and fracture surface shape characteristics of carbonaceous mudstone samples were analyzed, and the shear strength index of carbonaceous mudstone was obtained, and numerical simulations on the stability and support effect of carbonaceous mudstone slopes were conducted. The research results indicate that carbonaceous mudstone can exhibit good structural properties and typical strain softening characteristics under natural conditions. The fracture surface, shear strength, and shear deformation process of carbonaceous mudstone samples will undergo significant changes after being soaked in saturated water. The average cohesion decreases by 33% compared to the natural state, and the internal friction angle decreases by 15%. The numerical simulation results also fully verify the attenuation of mechanical properties of carbonaceous mudstone after immersion, as well as the effectiveness of prestressed anchor cables and frame beams in supporting carbonaceous mudstone slopes. The research results provide an effective method for understanding the shear performance of carbonaceous mudstone and practical guidance for evaluating the stability and reinforcement design of carbonaceous mudstone slopes. Full article

The Wangfu Fault Depression (WFD) is located in the southeastern uplift zone of the Songliao Basin and is an important geological site for studying tectonic evolution and volcanic stratigraphy. This study explores the complexity of the structure of the depression and the volcanic stratigraphy. The sedimentary sequence is divided into rift period and post-rift deposition, and the volcanic rocks are mainly concentrated in the Huoshiling Formation. Rhyolite deposits mark the bottom of the Yingcheng Formation. The volcanostratigraphic sequences are described by a detailed analysis of the seismic profiles, cutting samples, core data, geochemical, and well logging data, revealing the interaction between tectonic dynamics and volcanic activity. The volcanic facies are divided into vent breccia, pyroclastic, lava flow, and volcaniclastic sedimentary types, highlighting the diversity of depositional environments. In addition, the study identified key volcanic stratigraphic boundaries, such as eruptive and tectonic unconformities, which illustrate the alternation of intermittent volcanic activity with periods of inactivity and erosion. The study highlights the important role of faults in controlling the distribution and tectonic characteristics of volcanic rocks, and clearly distinguishes the western sag, middle slope, and eastern uplift zones. The chronostratigraphic framework supported by published U-Pb zircon dating elucidates the time course of volcanic and sedimentary processes, with volcanic activity peaking in the Early Cretaceous. Overall, the Wangfu Fault Depression is a dynamic geological entity formed by complex tectonic-volcanic interactions, providing valuable insights into the larger context of basin evolution and stratigraphic complexity. Full article

In order to alleviate the risk of landslides on high and steep slopes during excavation, slope protection coal pillars are commonly increased at the site to maintain slope stability, which causes a considerable waste of coal. In roof cutting for pressure relief at quarries, the movement of the overburden structure is artificially regulated by blasting. However, there is a lack of theoretical research on the impact on the slope movement. In order to explore how blasting roof cutting affects the deformation and fracture of slopes, a case study of the 10101 working face of Xinyuan Coal Mine was carried out. The particle flow code numerical simulation of the mining with different heights of roof cutting was performed to analyze the impact of the height of roof cutting on the movement of overlaying rock formation, the development of slope fractures, stress distribution, collapse angle, slope deformation and fracture, etc. The research results are as follows: the overlaying rock formation can be divided into the stable zone, the rotary zone and the subsidence area by displacement; a reasonable roof-cutting height allows the cutting and crushing of the overlaying rock formation, as a result of which the movement boundary is offset to cutting line and the slope is within the stable area; at the same time, the horizontal displacement of the rock formation in the rotary zone, the collapse angle and the stress at slope bottom are reduced, which controls the deformation and failure of slope by inhibiting the development of cracks at slope bottom and reducing the rotation of the rotary zone to the goaf zone. The research results provide certain references for controlling ground sedimentation and slopes in blasting roof cutting. Full article

Bio-slope engineering protection plays an important role in preventing soil erosion, enhancing slope stability, and improving soil and water conservation capabilities. To establish a foundation for the preparation of modified soil for bio-slope engineering, the common gravel soil used in bio-slope engineering protection was selected. Amendments such as peat soil and water-retaining agents were then incorporated to support these preparations. This study examines the influence of the content of peat soil and water-retaining agent on the modified soil’s moisture constants, infiltration coefficient, and water absorption capacity. Additionally, utilizing remote sensing technology, 20 rock cutting sites sprayed with vegetation were monitored over a 15-year period. The results suggest that the addition of peat soil and water-retaining agents aids in augmenting the available water capacity and water absorption speed of the soil, allowing it to absorb and retain a substantial amount of available water capacity. However, as the content of peat soil increases, the modified soil’s wilting point improves, while the infiltration coefficient increases. Based on the findings of the optimum proportion tests and the field spraying experiments, it is recommended that the proportion is granular soil with 80%, peat with 20%, water-retaining agent with 1.0‰, aggregate agent with 1.0‰, and fertilizer with 100 g/m². A comprehensive analysis of the spatial–temporal evolution characteristics of vegetation cover in the area post-railway construction indicates that vegetation cover in this region wilted extensively only in 2011 due to drought. Subsequently, the vegetation on the sprayed rock slopes has thrived, according to the proportion. The research findings are of considerable importance for guiding the design and construction of substrate spraying for bio-slope engineering protection in railway construction. Full article

Redbed soft rocks, widely distributed in China, are highly susceptible to weathering, disintegration, and strength reduction under environmental and engineering disturbances, posing critical challenges for slope stability. This study investigates the stability and failure mechanisms of high road-cut slopes in redbed regions under excavation, seismic, and rainfall conditions. Numerical simulations were conducted based on actual engineering sites, using the FLAC3D finite difference model to simulate conditions typical of these sites while incorporating realistic geological features such as weak interlayers and fluid–solid coupling effects. Results reveal that under excavation, the slope exhibits displacement discontinuities and stress concentration near weak interlayers. However, the safety factor of the redbed slope remains at 1.58 at this stage, suggesting that large-scale collapses or landslides are unlikely. Seismic loading amplifies displacements and accelerations, with the maximum deformation reaching a shear displacement of 0.81 m, observed in the upper sections of the redbed slope. Under prolonged rainfall, the slope experiences increased saturation and sliding along interlayer surfaces, driven by reduced shear strength. Combined influences of these factors highlight the vulnerability of redbed slopes to localized failure in weakly weathered zones, necessitating targeted reinforcement strategies. These findings provide a deeper understanding of redbed slope behavior under complex conditions, addressing key challenges in geotechnical and transportation infrastructure engineering. Full article

This study addresses critical stability concerns along a key segment of the Egyptian highway linking Aswan and Cairo, focusing on a one-kilometer rock-cut section that is vital for transportation and commerce. Recent evaluations have highlighted significant rockfall and slope instability risks in this area, posing serious safety challenges. The primary objective is to identify and analyze the factors contributing to slope instability, assess potential rockfall hazards, and recommend effective mitigation strategies. To achieve this, this study employs a comprehensive, multi-faceted methodology. Key variables influencing slope stability are first identified, followed by a detailed analysis of discontinuity data using stereographic projection based on joint surveys. Rockfall propagation distances are then modeled through specialized software, while the Plaxis 2D tool 2023.2(V23.2.0.1059) is applied for advanced numerical modeling of slope behavior. The results indicate a pressing need for mitigation measures to address ongoing instability issues, including planar and wedge failures and raveling rockfalls, which pose considerable safety risks to road users. This study highlights the necessity of a robust and comprehensive mitigation strategy to ensure road safety and support uninterrupted commercial activity along this essential highway. Full article

To investigate the evolution characteristics of overlying rock fractures, based on a geological prototype of a large-height comprehensive mining face in Shanxi, a three-dimensional large-scale physical similarity model was established. The experiments were carried out using microseismic monitoring and physical model cutting methods to study the activity and fissure evolution of the overburden rock. Model cutting revealed that, approximately 65 m from the bottom of the coal seam, delamination occurred, marking the top of the overburden rock fissure zone and the bottom of the bending and sinking zone. At 25 m from the coal seam bottom, the rock layer was highly fragmented, forming the collapse zone, which was 4.8 times the mining height. Between 25 and 65 m from the bottom, a fissure zone existed, which was 12.5 times the mining height, with abundant delamination fissures at the top of the fissure zone. Significant microseismic events were observed as the coal face advanced to 45 m, with notable increases in the concentrations and distribution ranges of these events in both the strike and height directions of the coal seam. The subsidence range of the overlying rock layer expanded from the top to the bottom, with the subsidence slope area extending gradually and the central compaction area remaining relatively flat. The overall shape presented an irregular ellipse, with peripheral uplift phenomena observed in the subsidence area. At 39 m from the coal seam bottom, the maximum subsidence of the rock stratum was 4.0 m, with subsidence amounts decreasing with increasing stratum height. Fissure density along the coal seam inclination and direction exhibited a double hump pattern, with fissure areas on both sides showing high densities and the central compaction areas having low densities. Coal seam mining caused stress redistribution in the surrounding rock layer, and the stress in front of the work was divided into the stress reduction zone, dynamic influence zone, mining influence zone, and unaffected zone. Coal rock porosity under high stress was less sensitive to stress changes, resulting in smaller changes in fissure permeability and fissures remaining mostly closed. Full article

The high exploration and development production capacity of the Jiyang Depression, Bohai Bay Basin, China in the early stage confirms the huge exploration and development potential of shale oil in the study area. Due to the complexity of the depositional mechanism in the study area, the distribution law of fine-grained sedimentary rocks is not well understood, which restricts further exploration breakthroughs. This paper comprehensively observes rock cores and thin sections, combines mineral components, Rock-Eval pyrolysis, rock-cutting logging and logging data to classify lithofacies, and clarifies the distribution law of various lithofacies. The research results show that, according to lithological characteristics, various lithofacies origins are classified into three categories: terrigenous, mixed, and endogenous sources, and six lithofacies types are distinguished: terrigenous low-organic-matter massive siltstone (LF1), terrigenous low-organic-matter massive mudstone (LF2), mixed-source medium-organic-matter massive mudstone (LF3), mixed-source medium-to-high-organic matter laminated-massive mudstone (LF4), mixed-source medium-to-high-organic-matter laminated mudstone (LF5), and endogenous-sourced medium-to-high-organic matter laminated limestone (LF6). The distribution of lithofacies in plane is symmetrical in the east–west direction and is characterized by a banded distribution; the distribution in profile shows a stable depositional process and a continuous depositional sequence. The various lithofacies depositional models have been summarized; the terrigenous input from the northern steep-slope zone has influenced the hydrodynamic conditions of the lake basin, significantly affecting the lithofacies depositional variations from the steep-slope zone to the deep-sag area. The geological evaluation of each lithofacies has been conducted; LF1 + LF4 + LF5 are classified as Class I—target reservoirs for shale oil development, while LF3 + LF6 are considered Class II—favorable reservoirs. The result of the study provide a reference for the classification of fine-grained sedimentary-rock facies and distribution characteristics, and the evaluation of shale-oil-reservoir sweet spots in graben lake basins. Full article

According to this study’s findings, slope stability problems in open-pit coal mines can be avoided, and mine wall collapse can be effectively mitigated by the use of cut-and-backfill mining techniques. The main research results are as follows: (1) The stope and waste rock’s geotechnical, physical, and mechanical characteristics were gathered and examined; the geotechnical and mechanical characteristics found in this study largely satisfy the criteria for slope stability analysis. (2) Cemented paste backfill (CPB) materials were made of mine waste rock and fly ash at a desired ratio, mixed with cement as a bond material, and were tested in the laboratory, using a combination of cement percentages of 6%, 8%, and 10% for the cement content and 25%, 30%, 35%, and 40% for the fly ash content, to determine the ideal mix for artificial ground support in underground mines, taking into account both economic and performance factors. (3) By using this model, the changes in CPB strength were investigated under various factors influencing the cement ratio, and limit equilibrium modeling was used with the FLAC-Slope 8.1 program with different cement paste backfill ratio to calculate the factor of safety for each cement percentage after 1 day, 3 days, 7 days, and 28 days of curing time (CT) to obtain the optimum compressive strength and shear straight of cemented paste backfill with high paste fill shear strength on the slope. (4) The research results are of great significance for the safety of important facilities in open-pit mines and provide a basis for the design and safety implementation of open-pit slope engineering. Full article

Geological structures significantly influence mining-induced deformations in open-pit mines, with their variations and interactions adding complexity to the excavation process and introducing uncertainties in deformation outcomes. This study utilized numerical simulations to analyze the impact of weak rock zones in a specific open-pit limestone quarry in Japan on mining-induced deformation. The simulation results were both qualitatively and quantitatively validated against field measurements, enhancing the reliability of the findings. Subsequently, four conceptual models were developed based on the characteristics of the quarry to investigate the mechanisms by which weak rock zones affect rock slope deformations. Our analyses demonstrated that slip deformation occurred exclusively when two weak rock zones were connected. This deformation was associated not only with shear failure in the upper weak rock zone but also with the contraction and bending of the lower weak rock zone. Furthermore, the simulation results were consistent with field data and supported by the conceptual models, confirming that the proposed sliding mechanisms can effectively explain the observed deformation behaviors. The insights gained from these models provide valuable references for managing similar geological challenges in other open-pit mines. Full article

A very common hazard in Rwanda is represented by the instability of steep road cut slopes in lateritic soil. In its natural state, this material appears as a fine-grained weak and altered rock, generally in unsaturated conditions. Steep cut slopes made by this material could remain stable for a long time unless weathering weakens its mechanical behavior and heavy rainfall provokes a rapid landslide. This paper presents the results of an experimental investigation on the microstructural, petrophysical, and geotechnical properties of lateritic soil from a road cut slope located in Kabaya (Ngororero District—Rwanda), which was recently subjected to a landslide. The mechanical properties of the material are strictly related to the geological origin and history of the deposits, their formation environment, and weathering processes. These characteristics were revealed by peculiar microstructural features (micro-texture, porosity, and degree of alteration of original mineral paragenesis). The experimental investigations included identification and classification tests, direct shear tests on saturated samples, and swelling tests. This multidisciplinary approach provided insights into the relationship between geotechnical properties and the microstructural, petrophysical, and chemical characteristics of the altered rocks. This study showed how different levels of chemical alteration operated by weathering processes, in conjunction with brittle deformation related to the tectonic history, formed in the same site two shallow rock layers with similar macro-scale features and mechanical behaviors but markedly different microstructural and chemical properties. The innovative aspect of this research suggests an integrated multidisciplinary approach to considering microstructural aspects in addition to mechanical behavior in the slope stability analyses in lateritic soil. In particular, this study demonstrates the importance of such an approach since the failure mechanism is better explained if it is based on microstructural observations instead of considering the soil shear strength parameters only. This research helped to explain the formation of the landslide failure mechanism in a specific road cut slope, which could be assumed as representative of many other similar slopes subjected to landslides in Rwanda. Full article

The red beds that are widely distributed in hilly areas in eastern Sichuan Province are inevitable rock and soil masses in engineering construction. In order to obtain a larger building area, engineering slope cutting is quite common in red bed hilly areas. Engineering slope cutting destroys the inherent stability of a slope and causes geological disasters. In order to practice the concept of sustainable development and explore ways to develop and utilize land resources reasonably and reduce the possibility of geological disasters caused by engineering slope cutting, this paper took the slope cutting sites caused by rural housing construction in the red bed area of Wanyuan City as research objects. The internal and external factors affecting the stability of the cut slopes were summarized through a field investigation, and two typical slopes were selected for analysis. Sampling and indoor tests were conducted to obtain the geotechnical parameters. Geo Studio software (2018 R2) was employed to establish numerical models, simulate the stress and strain distributions, and compute stability coefficients under different slope cutting conditions at the same time. Based on field investigations and numerical simulations, the three main failure modes of shallow landslides caused by slope cutting were summarized, and the evolution process of slope landform accelerated by slope cutting activities was deduced. In an engineering application, the functional relationship between the cutting height and the stability coefficient was fitted. It was found that the critical cut height values of soil slope were 6.3 m, 6.2 m, 5.2 m, and 2.6 m at slope of 10°, 20°, 30° and 40°, respectively; the critical cut height values of rock–soil mixed slope were 9.3 m, 6.5 m, 5.9 m, and 2.2 m at slope of 10°, 20°, 30° and 40°, respectively. The research findings can be used to prevent and manage the hazards caused by slope cutting in this study area. Full article

The mountainous areas of Southwest China have the characteristics of valley deep-cutting, a large topographic gradient, complex geological structures, etc. With the development of infrastructure construction in the area, the construction of bridges across valleys has gradually increased, and the phenomenon of slope failure occurs more and more frequently. As the weak interlayer, the fault fracture zones have a significant influence on the geological structure and stability of slopes, while the complexity of the mechanism of the deformation and failure of slopes increases with the combination of the development of the fracture zones and toppling deformation. This paper took the toppling bank slope of bridge foundations developed with fault fracture zones in Lancang River as the research object. Through an on-site field survey and geological survey technologies, it identified the distribution range of the fracture zones on the bank slope and determined the characteristics of the rock mass in the fracture zones. A stability evaluation model for the bank slope of the bridge foundations was established using the limit equilibrium method and discrete element method. Based on the two-dimensional limit equilibrium analysis, the potential failure modes of the bank slope were explored, and the stability of the bank slope under bridge loads was calculated. Through the three-dimensional geological model of the bank slope, including the fracture zones and toppling bodies, the three-dimensional discrete element numerical simulation method was adopted to simulate and calculate the deformation and failure process of the bank slope under different bridge loads and working conditions. According to the calculation results, the influence of bridge loads and reservoir water on the stability of the bank slope was analyzed from the perspectives of displacement, plastic zone, stability coefficient, and other factors. The formation process of the plastic zone and the development of the sliding surface were revealed, the incentive mechanism of bridge loads and reservoir water on the deformation and failure of the bank slope was analyzed, and the influence of fault fracture zones on the stability of the bank slope and the development of toppling deformation was determined. The results indicate that the fault fracture zones are important geological structures that affect the deformation and failure of the bank slope as a weak interlayer. Under the influence of bridge loads and reservoir water, the stability of the bank slope is affected by the quality of the rock mass and the development of the fault fracture zones, resulting in the unmet need for safety requirements and maybe leading to instability. Based on the calculation results of the stability evaluation prediction model for the bridge foundation bank slope and the engineering geological conditions, the bridge scheme has been selected. Full article

Gravitational processes on cut slopes located close to infrastructure are a high concern in mountainous regions. There are many techniques for survey, assessment, and prognosis of hazardous exogenous geological processes. The given research describes using UAV data and GIS morphometric analysis for delineation of hazardous rockfall zones and 3D modelling to obtain an enhanced, detailed evaluation of slope characteristics. Besides the slope geomorphometric data, we integrated discontinuity layers, including rock plains orientation and fracture network density. Cloud Compare software 2.12 was utilised for facet extraction. Fracture discontinuity analysis was performed in QGIS using the Network GT plugin. The presented research uses an Analytical Hierarchy Process (AHP) to determine the weight of each contributing factor. GIS overlay of weighted factors is applied for rockfall susceptibility mapping. This integrated approach allows for a more comprehensive GIS-based rockfall susceptibility mapping by considering both the structural characteristics of the outcrop and the geomorphological features of the slope. By combining UAV data, GIS-based morphometric analysis, and discontinuity analysis, we are able to delineate hazardous rockfall zones effectively. Full article

In 1999, Alberta Transportation and Economic Corridors (TEC) implemented the Geohazard Risk Management Program (GRMP) to identify, assess, monitor, and prioritize the mitigation of risk resulting from geohazard events at specific sites along the provincial highway network. The GRMP was developed to address a variety of geohazard types including rockfall hazards that occur at natural and constructed (cut) highway backslopes. An evaluation of various methods for the condition assessment of rockfall geohazards, including TEC’s current GRMP risk rating system, has been completed with the intent of better understanding the suitability of each method as TEC transitions to a formalized GAM program. The GRMP risk rating values for selected rockfall geohazard sites along highway corridors in Alberta were compared to values developed from the results of five established rock mass and rock slope rating systems. The results of this study demonstrate that TEC’s current GRMP risk rating system is a viable tool for the condition assessment and performance monitoring of rockfall geohazards, which could be utilized within a formalized GAM program, further benefitting from years of recorded application in Alberta. Of the other rating systems tested, the rockfall hazard rating system (RHRS) showed a strong correlation with the GRMP risk rating while Q-Slope, the Geological Strength Index (GSI) and Rock Mass Rating (RMR) correlation were marginal but displayed a potential for use as condition assessment tools. The work presented in this paper provides the first evaluation of rock slope rating systems for rockfall hazards along corridors in Alberta, directly comparing them to the slope performance as observed by TEC in a quantitative manner. Full article