Bulletin of Engineering Geology and the Environment最新文献

Current methods for obtaining surface deformation of landslides are mostly time-consuming, costly, and can only capture the motions of sparse points. By combining InSAR data and high-precision three-dimensional GNSS data, the three-dimensional deformation field can be obtained. This study introduces the Simultaneous and Integrated Strain Tensor Estimation from geodetic and satellite deformation Measurements (SISTEM) method into the retrieval process of landslide. This method can be very useful but has rarely been applied to the characterization of landslide kinematics. The results can be used in order to recognize the eventual presence of zones having different kinematics, so we apply SISTEM for the first time to detect 3D deformation on a reservoir slope in Yichang Province, China. The output of InSAR after calculating the atmospheric contribution by external data from the ERA-5 global meteorological model was integrated with local GNSS data into the SISTEM framework to decompose the measurements into a 3-dimensional velocity field. Finally, the kinematic characteristics of the studied landslide surfaces were determined. The middle region exhibits the highest deformation rate along the slope with the maximum horizontal deformation rate of 10 mm/a, primarily showing uplift with vertical deformation rates of 3 mm/a. In contrast, the rear of the slope experiences mainly downward movement, with a maximum vertical deformation rate of -15 mm/a. The proposed method provides a convenient and rapid way to obtain spatially continuous surface movement characteristics of landslides, offering a more direct and reliable scientific reference for landslide disaster warning and instability risk assessment.

Earthquakes, extreme rainfall, and other conditions can trigger a considerable number of shallow landslides, posing significant safety hazards. Due to the lack of obvious warning signs before sliding, such landslides are not apparent. Traditional remote sensing images and conventional aerial survey data cannot effectively and accurately reflect deformation-related warning signs of sliding. Thus, investigating the subsurface structural characteristics of slopes has become crucial for studying retrogressive shallow soil landslides. This paper takes the Zhongzhai landslide in Niangniangba town, Qinzhou District, Tianshui city, Gansu Province, China, as the research object. Electrical resistivity profiles of the landslide area were obtained by electrical resistivity tomography (ERT), using in situ light dynamic penetration tests and core drilling to confirm the relationship between resistivity and formation lithology to realize the fusion of multisource data. A three-dimensional model of electrical resistivity was constructed to characterize the stratigraphic structure. Combined with unmanned aerial vehicle (UAV) photogrammetry and on-site investigation to obtain terrain features, a three-dimensional geological model of the Zhongzhai landslide was constructed. The development process and genesis mechanism of landslides at the loess–bedrock interface were explored via numerical simulation. The results demonstrate how the stratigraphic structure and water table influence the development of retrogressive shallow soil landslides. This article can provide a reference for the stability evaluation and prediction of retrogressive shallow soil landslides.

Jointed rock masses are often subjected to complex cyclic shear loads, which may originate from factors such as earthquakes, mining activities, or traffic. Rock bolts are widely used to enhance the stability of jointed rock masses, and the mechanical behavior and failure characteristics of different types of rock bolts under shear conditions can significantly impact the shear resistance and overall stability of the rock structure. This study analyzed the cyclic shear performance of two types of rock bolts under varying normal stress conditions. The results showed that an increase in normal stress significantly enhanced the peak shear stress and shear resistance of the specimens by compacting the contact interface and increasing friction. However, at higher normal stresses, the contact interface between the rock bolt and the rock mass experienced greater stress concentration, which could lead to early bolt failure. Although fully-grouted rock bolts exhibited strong mechanical interlock and high initial shear strength, they were more prone to brittle fracture due to localized stress concentration, increasing the risk of instability. In contrast, energy-absorbing rock bolts, through mechanisms of plastic deformation and energy absorption, effectively alleviated shear stress concentration and demonstrated better toughness and ductility. As normal stress increased, energy-absorbing rock bolts, with enhanced friction and a larger range of shear displacement, absorbed energy more effectively, resulting in a significant increase in shear energy-far surpassing that of fully grouted bolts, which relied primarily on mechanical interlock. Additionally, with repeated loading cycles, the shear stiffness of energy-absorbing rock bolts showed more gradual and stable degradation compared to fully grouted bolts.

Climate change is anticipated to have predominantly negative impacts on human habitats in the coming decades, leading to significant environmental transformations, including an increase in landslide frequency. This paper introduces a novel approach to evaluating the susceptibility of geological units (GUs) to landslides, based on an analysis of the energy relief index. The method is applied to Pannonian Croatia, specifically the North Croatian Basin and the Hrvatsko Zagorje Basin, where landslides are the predominant mass movement process. Previous attempts to create landslide susceptibility maps for Croatia did not adequately analyze landslide inventories. Our approach utilizes three key datasets: landslide inventory, geological maps, and relief energy, to clearly identify which GUs are most frequently in an unstable equilibrium state. The findings highlight that the youngest isolated Miocene unit (M₇) has the highest landslide susceptibility. This method shows significant promise by enabling precise identification of landslide-prone GUs and offering the potential for integration into the production of small-scale landslide susceptibility maps, particularly for determining weighting factors for GUs within specific study areas. However, it is crucial to ensure that the landslide inventory accurately represents the entire landslide population in the study area.

The capillary water absorption issues of the sandstone have significantly influenced their salt weathering conditions. This work aimed to explore the influences of different salt types and concentrations for the capillary water absorption of sandstone in Nankan Grotto. Three sets of capillary water absorption tests were designed. In addition, the mineralogical, major element, micro-structure, and physical properties of sandstone were also analysed. It is found that the mineralogical compositions of the sandstone were quartz, feldspar, illite-smectite mixed layer, illite, and chlorite. The water absorption weight curves showed three stages: rapid water absorption stage (0–4 h), slow water absorption stage (4–36 h), and inactive water absorption stage (after 36 h). The capillary rise height curves showed two stages: sharp increase in 0–20 min and very slow increase after 20 min. The capillary water absorption coefficient (A_cap) results revealed that all of the salt solutions (Na₂SO₄, NaNO₃, and Na₂SO₄ + NaNO₃) promoted the capillary water absorption in sandstone. The promoting effect of Na₂SO₄ solution was the most remarkable, followed by Na₂SO₄ + NaNO₃ solution. The promoting effect of NaNO₃ solution was insignificant. The maximum water absorption velocities under the NaNO₃ solution conditions were always greater than those under the Na₂SO₄ solution conditions, and smaller than that under deionized water. This was due to the highest viscosity of Na₂SO₄ solution. The Hall model fitted the capillary water absorption curves better than Feng and Janssen model. In addition, the modified model for capillary rise height prediction demonstrated good agreements with those obtained from experiments.

Microbial induced desaturation and precipitation (MIDP) has been proven to be an environmental-friendly and reliable method for liquefaction mitigation. This study further explored MIDP with yeasts that had better performance for soil desaturation. First, the growth characteristics of two kind of yeasts were analyzed. Then the gas production ability of yeasts was measured by drainage method. Finally, the shaking table test was conducted to investigate the liquefaction mitigation effect. The results showed that the yeast anaerobic gas production reaction can reduce the saturation degree of calcareous sand from 100% to 86.76%. In the shaking table test, bacterial solution of 4% sucrose content achieved the best desaturation effect, the saturation degree of the bottom layer could be reduced to 59.9%. The excess pore pressure ratio of the soil at the different depths had a decreasing trend. The change of soil shear wave velocity changes was tested after desaturation, and found that the shear wave velocity increased from 10 m/s to 70 m/s with a regularity as the saturation degree decreased. The results of this study provided a new perspective on yeast in calcareous sand desaturation.

Dynamic loading along the rock joints from factors such as thermal loads, excavation, and seismic wave velocity further exacerbates susceptibility. It is crucial to restore the strength of such rock masses using appropriate techniques to enhance the stability of slopes and tunnels and mitigate future distress and damage. This study investigates the impact of uniaxial loading on the peak strength and fracture propagation behaviour of non-persistent rock masses subjected to temperatures from 100 °C to 400 °C. These parameters have been examined in jointed samples (i.e., prepared by dental plaster (DP) with joint at 30° inclinations to the horizontal in the middle of the specimen) and filled with grouts using (i) cement, (ii) sand-cement mortar (in a 1:3 ratio) and bio-concrete (SCB) mix, and (iii) epoxy resin. The results reveal that grouting can mitigate the presence of defects in any rock mass. Without heat-treated specimens with epoxy grout are more effective than those with cement and SCB mix grout. The study also clearly delineates the effects of temperature variation on the strength behaviour of both un-grouted and grouted specimens. The strain field of samples without subjected to heat treatment varies from 0.01 to 0.25, 0.05 to 0.55, 0.02 to 0.14 and 0.01 to 0.1 in un-grouted, SCB mix, cement and epoxy grouted, respectively. In un-grouted specimens, strain increases with higher thermal treatments, transitioning from tensile to far-field failure modes. When grouting is introduced, an increase in strain is observed. In specimens grouted with SCB mix, shear cracks dominate up to 250 °C, after which far-field cracks appear. In cement-grouted specimens, far-field cracks are observed up to 200 °C, followed by a transition to tensile failure mode. However, far-field failure mode in epoxy grouted specimens initiates from the onset of thermal treatments, starting at 100 °C. The detailed observations on crack propagation along un-grouted and grouted specimens is made via Digital Image Correlation (DIC) and FracPaQ analysis. The DIC technique enables precise measurement of strain distribution and deformation, while FracPaQ provides detailed analysis of fracture networks and orientations.

3D geological modeling facilities the visualization of geological conditions to hone engineering decisions in the utilization of urban underground space, but it poses significant challenges due to multiscale application scenarios within different resolutions, as well as complex coupled modeling procedures between geometry and properties. Massive multisource geological data have been collected in Wuhan city. Nevertheless, a regional 3D geological model had not been established yet. To address these issues, a multigrid progressive 3D geological modeling scheme is proposed and then adopted to multiscale progressive 3D geological modeling in Wuhan city. Initially, the geological framework is established with grid division according to the regional geological evolution surveys, and 3D geological structure modeling is subsequently implemented by discrete smooth interpolation method leveraging borehole and synthetic data extracted from geological profiles with nodes identification. Following isochronous stratigraphy features analysis of geological properties and borehole density assessment within grid subdivision, the 3D property model is built using an optimized ordinary kriging method constrained by the multiscale structure model. Finally, the 3D geological model is validated and updated under the multiscale framework in conjunction with new site investigations. The multiscale progressive 3D geological modeling workflow is employed in urban metro construction scenarios, and it paves a way to promote the application of geological survey achievements in the whole life cycle of urban underground space development.