Bulletin of Engineering Geology and the Environment最新文献

Vegetation root systems are crucial for enhancing shallow slope stability. However, key mechanical responses—such as root penetration across slip planes and tensile restraint on slope scarps-remain insufficiently characterized, and few existing models adequately account for soil-rock interface features and root spatial architecture. Focusing on Robinia pseudoacacia stands in the Qinling Mountains, China, this study systematically explores root-reinforcement mechanisms through field investigations, laboratory testing, theoretical analysis, and finite difference modelling. Direct shear tests indicate that the shear strength of root-soil composites is collectively governed by root biomass, soil moisture, and root diameter, revealing a pronounced interactive interplay between soil hydrological conditions and mechanical behaviour. Specifically, the composite shear strength peaks at a root content of 0.6% and a moisture content of 16%, elevating root cohesion by up to 105.9%. Calibrated against experimental data, a theoretical analytical model and a finite difference numerical model integrating root reinforcement contributions are developed to formulate an evaluation framework for vegetated shallow slope stability. Quantitative comparisons across three root distribution scenarios reveal root anchorage reduces slope displacement by 73.5% and increases safety factors by 180% compared to bare slope. Mechanistically, roots deliver synergistic tensile, reinforcing, and anchoring effects that restrict soil displacement, limit slip surface propagation, homogenize subsurface stress fields, and increase safety factors. This work clarifies the stabilizing mechanism of Robinia pseudoacacia roots, laying a robust theoretical foundation for ecological slope protection relying on vegetation.

Five representative debris morphologies were constructed from quantitative morphology descriptors to investigate how particle shape influences the movement and accumulation behavior of dry debris flow. To assess morphology-dependent responses, sliding and rolling tests were conducted on representative debris blocks, and the movement characteristics of different shapes were compared. The collapse behavior of granular columns, flume movement, and depositional patterns of debris with different morphologies were then analyzed using the sphere discontinuous deformation analysis (SDDA) method. In addition, a real topographic case reconstructed from unmanned aerial vehicle photogrammetry was used to examine the movement and deposition behavior of morphology-controlled debris under complex terrain conditions. The results show that debris morphology significantly affects the mobility, collision and rolling behavior, and final accumulation pattern of dry debris flow. Flat and elongate debris are more likely to promote local accumulation, whereas spherical debris exhibits higher mobility and enhances the runout potential of the debris mass. These findings demonstrate that debris morphology is an important controlling factor in dry debris-flow analysis and should be explicitly considered in hazard assessment and engineering scenario evaluation.

Landslides in high mountain environments exhibit time-dependent deformation driven by the combined effects of hydrological loading, thermal conditioning, and episodic tectonic forcing. These interacting processes produce evolving slope instability that cannot be adequately represented by conventional static hazard assessments. This study presents a GIS-integrated SBAS-InSAR framework with geo-environmental temporal triggers for spatiotemporal landslide deformation analysis and dynamic risk characterization in the northwestern Himalayas of Pakistan. Surface deformation of three active landslides was analysed using ascending and descending Sentinel-1 images using SBAS-InSAR time series analysis for 2017–2025 years. The two viewing geometries enabled the characterization of deformation patterns while reducing geometric bias. Monthly displacement and velocity time series were systematically compared with rainfall, temperature, and seismic records to quantify the relative influence of triggering mechanisms. The results indicate a clear control hierarchy: rainfall derives sustained deformation and acceleration, temperature acts as a conditioning factor through delayed hydro-thermal processes and seasonal snowmelt while seismicity produces short-lived deformation perturbations. The findings demonstrate the importance of post-seasonal thermal–hydrological interactions in dynamic risk evaluation. Based on these observations, a dynamic risk classification framework was developed that links environmental trigger thresholds with InSAR-derived deformation metrics to quantify monthly variations in landslide risk. The proposed approach captures progressive acceleration, post-seasonal responses, and intermittent instability that are not addressed by traditional static susceptibility or rainfall-only models. This framework provides a transferable, process-based methodology for time-resolved landslide risk assessment in climatically and tectonically complex mountain regions.

Preloading is a widely adopted technique for reducing secondary compression—axial creep under oedometric conditions—in soft ground, and it is commonly implemented in conjunction with the installation of vertical drains. The installation of vertical drains alters the drainage paths and may introduce additional uncertainty in long-term settlement prediction. However, the influence of drainage direction on creep behavior has not been sufficiently quantified in the literature. This study quantitatively evaluates the effect of drainage direction on creep behavior during different loading phases associated with preloading in soft ground. A series of oedometer tests was conducted under vertical and radial drainage conditions using reconstituted kaolinite samples and undisturbed samples obtained from the Nakdong River intertidal zone in South Korea. Under surcharge loading, secondary compression was greater under radial drainage. After unloading, although swelling under radial drainage was generally larger, creep reappeared earlier and developed to a greater extent. During reloading, secondary compression was again greater under radial drainage. Taken together, these results show that radial drainage consistently leads to larger long-term settlements across different stress stages. The findings of this study suggest that the installation of vertical drains could influence creep behavior under certain preloading-induced stress conditions, thereby increasing uncertainty in long-term settlement control of soft ground.

The impoundment of large reservoirs often reactivates ancient landslides, posing significant risks to infrastructure such as tunnels that traverse these unstable slopes. This study investigates the deformation behavior of the Dawanzi (DWZ) tunnel, which orthogonally passes through the Tuandigou (TDG) landslide in the Baihetan Reservoir Region, China. Field monitoring, numerical simulation, and theoretical analysis were employed to examine the interaction between the landslide and the tunnel during reservoir impounding. Results indicate that the TDG landslide, initially stable, experienced accelerated deformation when the reservoir water level exceeded 810 m, with cumulative surface displacements reaching 299.1–1146.8 mm by January 2023. Correspondingly, the tunnel section within the landslide (K8 + 479—K8 + 553) exhibited significant distress, including concrete cracking, spalling, and diameter expansion. Numerical simulations revealed a reduction in the landslide safety factor with rising water levels, and an elastic beam model was applied to analyze the tunnel-landslide interaction mechanism. To ensure long-term safety, a rerouting scheme for the affected tunnel section is proposed, bypassing the landslide area. The findings provide valuable insights for the design and risk mitigation of tunnels in reservoir-affected landslide regions.

In order to fully comprehend the effect of faults on fluid flow and mass transport, it is essential to determine the permeability distribution in the rock matrix surrounding such faults. In the present study, permeability measurements were performed in the vicinity of a subvertical Main Shaft Fault (MSF) at the Mizunami Underground Research Laboratory, Gifu Prefecture, central Japan. The permeability of granite exposed on a tunnel wall at depths of 200, 300, and 500 m was measured using a probe permeameter at various distances from the MSF. The region of highest permeability showed a clear dependence on both the depth and the distance from the fault. At a depth of 300 m, the highest permeability was observed at a distance of 30–40 m from the MSF, whereas at a depth of 500 m, high permeability was found in the vicinity of the MSF and a secondary fault. The cumulative frequency of fractures with a length ≥ 0.01 m estimated by extrapolating a power law for the macroscopic fracture frequency showed a weak positive correlation with the permeability at a depth of 300 m, but a negative or unclear correlation at a depth of 500 m. This inconsistency is presumably caused by differences in the intensity and type of processes that modified the matrix permeability after formation of the damage zone at these two depths.

As underground engineering extends to depths of thousands of meters, fault-slip rockbursts induced by stick-slip instability pose a major safety threat. Most laboratory studies on fault stick-slip have used constant normal load (CNL) conditions, ignoring the effects of rock type and normal stiffness—key factors inherent to natural deep faults. To address this, this study employs granite and marble as representative lithologies, and a series of friction sliding experiments were conducted on rock simulated faults under constant normal stiffness (CNS) boundary conditions. The research systematically investigates the coupled regulatory mechanisms of lithological differences and normal stiffness effects on fault stick-slip instability characteristics. Results show that: (1) Both lithologies exhibit regular stick-slip patterns under varied normal stiffness, with granite also showing regular inclusion chaotic stick-slip modes suppressed by increasing stiffness. (2) Seismic source parameters generally increase with normal stiffness for both rocks, but maximum shear and normal stresses increase with stiffness for granite and decrease for marble. (3) Theoretical analysis indicates granite faults are more prone to unstable slip, especially under CNL conditions. From a mineralogical perspective, the controlling factors of stick-slip behavior rank as: mineral composition > grain size > mineral stability. Notably, the influence of these factors may be further exaggerated by the effect of normal stiffness. These research findings offer invaluable insights into the intricacies of deep fault slip behavior.

The mechanical properties of rock structural planes exert a significant influence on the seismic performance of rock slopes. Although laboratory tests have confirmed the dynamic degradation of shear strength along rock structural planes under cyclic loading, most existing studies characterize this behavior using the traditional Coulomb-slip model, assuming constant shear strength throughout the analysis. To overcome this limitation, this study introduces a numerical framework for simulating the seismic displacement and failure characteristics of rock slopes accounting for the dynamic degradation of rock structural planes. It is then employed to systematically investigate the influence of dynamic degradation of sliding surface on the seismic displacement and failure characteristics of rock slopes, with particular attention to their response to pulse-like ground motions. The results show that accounting for the dynamic degradation of rock structural planes increases the seismic displacement of the slope case by approximately 54%. Moreover, compared to non-pulse-like ground motions, pulse-like ground motions induce significantly larger seismic displacements—up to about 13.3% greater of the slope case. These findings could hopefully assist in assessing the seismic risk of rock slopes subjected to strong pulse-like ground motions.

Although research on freeze–thaw(F-T) damage of engineering materials in cold regions is relatively mature, there remains a significant lack of research on the fracture behaviour of interfacial roughness coupled with F-T damage. For this reason, this study employed a multi-scale approach, combining shear tests, acoustic emission (AE), digital image correlation (DIC), scanning electron microscopy (SEM), and theoretical analysis. The results showed that F-T cycles significantly degraded the mechanical properties of the sandstone-concrete, while roughness effectively improved its shear resistance. Acoustic emission and DIC analyses jointly revealed that F-T action induced a shift from shear- to tensile-dominated damage modes and suppressed crack extension, while roughness induced crack bifurcation and complex fracture networks. The microscopic characterisation (SEM) further indicated that F-T-induced sandstone fracture was transformed by crystal penetration and an increase in concrete porosity. It ultimately led to the migration of the fracture path towards the concrete side. On this basis, we propose for the first time a straight shear full-stage constitutive model that takes F-T damage into account, which is in high agreement with the experimental data. The outcomes of this research provide strategic guidance for optimising design codes and developing effective maintenance strategies for infrastructure in F-T environments.

Understanding the evolution of shale microstructures under mechanical stress is critical for predicting reservoir behaviour in unconventional energy development. This study investigates the poromechanical response of Krishna-Godavari Basin shales using a multi-technique approach that combines in-situ X-ray micro-computed tomography, mercury intrusion porosimetry, and low-pressure gas adsorption (N₂ and CO₂). Cylindrical core plugs were subjected to progressive stress conditions (0–22 MPa) while being imaged in real time to capture microfracture initiation, propagation, and pore network reorganisation. Results show a clear transition from isolated micropores to larger, interconnected pore systems as stress increased. Micro-CT data reveal that void volume fraction increases from 0 to 22 MPa, with coordination numbers and permeability rising in tandem. Progressive loading increases the pore connectivity. Permeability increases from 0.05596 millidarcy to 2.2496 millidarcy as the applied stress increases from 0 MPa conditions to a stress of 22 MPa. Elastic behaviour continued up to 11 MPa, followed by crack nucleation at 11 MPa, stable crack propagation up to 19 MPa, and eventual coalescence and failure at 22 MPa. Pore network modelling confirmed that mechanical loading enhanced connectivity by merging smaller pores into larger, transport-efficient pathways. These changes reflect stress-induced systematic microstructural reorganisation, demonstrating the stress-sensitive nature of shale pore systems. The novelty of this work lies in its real-time, multiscale characterisation of poromechanical evolution, directly linking microstructural alterations to permeability gains. The findings have broad implications for optimising hydraulic fracturing design, forecasting hydrocarbon recovery, and improving geomechanical models of shale reservoirs.