Engineering Geology Research Articles

Landslide susceptibility evaluation and determination of critical influencing factors in eastern Sichuan mountainous area, China

Landslide susceptibility evaluation and determination of critical influencing factors is a prerequisite for preventing hazardous risks, especially in landslide-prone mountainous areas. However, in densely vegetated Southwest mountainous areas, identifying assessment approach of shallow landslides susceptibility and their major inducing factors is still a huge challenge. To address this challenge, we applied five advanced machine learning models (Logistic Regression Model, Generalized Additive Model, Random Forest Model, Support Vector Machine Model, Artificial Neural Network Model) to assess the spatial distribution of shallow landslide susceptibility, considering several relevant factors that affect landslide occurrence. These factors include geological, topographic and vegetation factors, as well as four new vegetation factors: stock volume, stand density, average tree age, and stand types. Furthermore, we employed SHAP algorithm and Structural Equation Models to quantify the relative importance and explanatory power of these factors on shallow landslide susceptibility and to clarify the interaction mechanisms among various factors in Huaying Mountain. The results shown that Random Forest Model proves to be the most accurate (95.1 %) in assessing the spatial distribution of shallow landslides susceptibility, followed by the Artificial Neural Network model (78.6 %), the Support Vector Machine model (69.8 %), the Generalized additive model (68.1 %) and the Logistic Regression model (67.6 %).The area with high susceptible landslide possibility was 25.3 km2 occupying 14.8 % of the study region, it is mainly distributed in the west of Tianchi Lake, southeast of Huaying City and west of the study area, along with Xiangyu Railway. Geographical environment and vegetation features were found to significantly explain 67.4 % and 32.6 % of the total effects in shallow landslides susceptibility, respectively. Specifically, the spatial distribution of shallow landslides susceptibility were primarily influenced by geological engineering rock group, distance to faults、stand types and distance to river. Geographical environment factors could indirectly affect changes in vegetation features, thereby indirectly affecting the spatial distribution of shallow landslides susceptibility. Findings from this research could be helpful for scientific decision-making and technical assistance for early warning, prevention, and control of rainstorm-induced landslides in highly vegetation covered areas.

The Life and Times of Peter George Fookes: 1933–2020

This paper is a personal review of the life and career of Peter Fookes, probably the most influential engineering geologist of his time. It includes personal recollections, a review of his 200 technical publications, his professional career and his influence on how geotechnology is viewed and used by the civil engineering profession. Perhaps his greatest epitaph is the development and use of the Ground Model.

About this title - The Peter Fookes Engineering Geological Legacy in Geomodels, Geomaterials and Geomorphology

This book commemorates the life, work and heritage of Professor Peter Fookes (1933–2020) who worked in over 100 countries and produced some 200 publications. He was the recipient of the William Smith and Glossop medals and was renowned for his pioneering work in engineering geomorphology, geomaterials and the development of ground models for engineering geology.

Evolution of the Yigong river channel on the Eastern edge of the Qinghai-Tibet Plateau: insights from hydrodynamic geological hazards shaping topography

Geological action is one of the main forces in the formation of topography, especially in the southeastern part of the Qinghai-Tibet Plateau. Collapse, landslide, mud-rock flow and other geological actions are the main factors affecting the evolution of river valley landforms. However, existing inference methods primarily rely on theoretical calculations and multi-temporal remote sensing image interpretation, lacking direct analysis and validation through geological exploration techniques. In response, this study employed geological engineering and geotechnical exploration techniques to investigate the impact of debris flows, landslides, and collapses on the evolution of topography and geomorphology in a 5.0 km section of the Yigong Zangbo Basin. Through drilling and geophysical exploration, 6 geological profiles were constructed, identifying the distribution range and development characteristics of the geological phenomena within this section of the river valley, revealing the distribution positions of both the new and old river channels, and inferring the evolution of the river bedrock based on the original topography. The study found that when geological phenomena occur, substantial material is transported into the river channel, altering its original shape and influencing the river’s erosion process. Additionally, the occurrence of geological phenomena is closely correlated with the evolution of river valley morphology. When the river valley is wide, material accumulation on one side causes the river to flow along a lower position on the opposite side, primarily resulting in the river’s bending on the plane. In contrast, in narrow river valleys, material accumulation on the sides can fill the entire river channel, leading to a rise in the riverbed. These research findings provide a critical theoretical basis for understanding river valley morphological evolution and informing basin engineering construction.

Probabilistic fault displacement Hazard analysis in an extensional setting: Application to a strategic Dam and methodological implications

We present a Probabilistic Fault Displacement Hazard Analysis (PFDHA) for a strategic dam located in the Upper Tiber Valley (Northern Apennines of Italy) claimed to be sited on a supposed capable fault (Montedoglio fault). We verify the seismic capability of the Montedoglio fault through detailed geological and geophysical analyses. We find no evidence for considering the Montedoglio fault as an active and capable structure, the fault being constituted by a system of discontinuous parallel faults, apparently inactive since more than 56 ± 3 ka, and likely unable to nucleate strong surface rupturing earthquakes. Since the dam lies on the hanging wall of the closest major active fault of the area (Anghiari normal fault, ∼1.5 km away), we investigate the likelihood of having distributed faulting at the dam's site in case of a strong surface-rupturing earthquake occurring on the Anghiari fault. We apply a probabilistic approach to obtain hazard curves of exceedance of vertical displacement at the dam's site for different rupture scenarios. We show that the mean hazard curve is always below an annual frequency of exceedance of 1 × 10−5, corresponding to displacement values below 1 cm over 100,000 years of return period. The study highlights several weaknesses and uncertainties in using PFDHA with state-of-the-art models, suggesting the need for improvements to enhance their applicability in earthquake engineering geology practice.

Comparative evaluation of machine learning models for assessment of seabed liquefaction using finite element data

Predicting wave-induced liquefaction around submarine pipelines is crucial for marine engineering safety. However, the complex of interactions between ocean dynamics and seabed sediments makes rapid and accurate assessments challenging with traditional numerical methods. Although machine learning approaches are increasingly applied to wave-induced liquefaction problems, the comparative accuracy of different models remains under-explored. We evaluate the predictive accuracy of four classical machine learning models: Gradient Boosting (GB), Support Vector Machine (SVM), Multi-Layer Perceptron (MLP), and Random Forest (RF). The results indicate that the GB model exhibits high stability and accuracy in predicting wave-induced liquefaction, due to its strong ability to handle complex nonlinear geological data. Prediction accuracy varies across output parameters, with higher accuracy for seabed predictions than for pipeline surroundings. The combination of different input parameters significantly influences model predictive accuracy. Compared to traditional finite element numerical methods, employing machine learning models significantly reduces computation time, offering an effective tool for rapid disaster assessment and early warning in marine engineering. This research contributes to the safety of marine pipeline protections and provides new insights into the intersection of marine geological engineering and artificial intelligence.

Engineering Geological Characterization and Slope Stability Analysis of Soils Along the Blue Nile Basin Road Section, Northwestern Ethiopia

Engineering Geological Characterization and Slope Stability Analysis of Soils Along the Blue Nile Basin Road Section, Northwestern Ethiopia

Key Technology for Leak Prevention of Igneous Rocks in a Certain Oilfield in Bo Zhong

A certain oilfield in Bozhong has experienced multiple volcanic eruptions, with developed fractures in igneous rocks and frequent drilling leaks; In the early stage, 7 out of 8 exploration wells experienced 23 leaks, resulting in losses of over 24 million yuan. In response to the high risk of leaks in the igneous rock development area of this block, based on the concept of geological engineering integration, an innovative key technology for preventing leaks in igneous rocks in a certain oilfield in Bozhong was proposed, with "pre drilling prevention, monitoring while drilling, and rapid plugging" as the core. Through 30 on-site construction operations, a new operational approach was provided for the problem of leaks in igneous rock formations, effectively reducing drilling risks and costs.

Relationship between root characteristics and saturated hydraulic conductivity in a grassed clayey soil

Soil saturated hydraulic conductivity plays a crucial role in the fields of hydrology, geotechnical and geological engineering. This study investigated the relationship between root characteristics and soil saturated hydraulic conductivity in a grassed soil. The saturated hydraulic conductivity of soil specimens with varying soil dry densities and planting densities were experimentally determined. Root parameters of each specimen were measured, and the relationship between root parameters and soil saturated hydraulic conductivity was determined through the stepwise multiple regression analysis. Experimental results show that both soil dry density and planting density significantly influence root growth and the saturated hydraulic conductivity of the grassed soil. Root length ratio (>4 cm), root length, and root weight density exhibit a positive correlation with planting density, while root length density and root length ratio (>4 cm) are negatively correlated with dry density. Higher dry density leads to lower soil saturated hydraulic conductivity and the permeable effects become more pronounced with increased planting density. When planting density is higher, roots create more preferential flow channels in the soil, resulting in increased soil saturated hydraulic conductivity. Root length density exerts the most significant effect on soil saturated hydraulic conductivity (|r| = 0.82, p＜0.01), followed by root length ratio (>4 cm) and root weight density. This study provides insights into the relationship between root parameters and soil saturated hydraulic conductivity, and identifies key root parameters that govern the saturated hydraulic conductivity of soil. These findings hold significant implications for enhancing the understanding of slope protection using vegetation.

Geological and Engineering Integration Fracturing Design and Optimization Study of Liushagang Formation in Weixinan Sag

The Weixinan Sag in the Beibuwan Basin is rich in shale oil resources. However, the reservoirs exhibit rapid phase changes, strong compartmentalization, thin individual layers, and high-frequency vertical variations in the thin interbedded sandstone and mudstone. These factors can restrict the height of hydraulic fracture propagation. Additionally, the low-porosity and low-permeability shale oil reservoirs face challenges such as low production rates and rapid decline. To address these issues, the Plannar3D full 3D fracturing model was used to simulate hydraulic fracture propagation and to study the main controlling factors for fracture propagation in the second member of the Liushagang Formation. Based on the concept of geological–engineering integration, a sweet spot evaluation was conducted to identify reservoirs with relatively better brittleness, reservoir properties, and oil content as the fracturing targets for horizontal wells. The UFM model was then applied to optimize fracturing parameters. This study indicates that the matrix-type oil shale has a high clay mineral content, resulting in a low Young’s modulus and poor brittleness. This makes hydraulic fracture propagation difficult and leads to less effective reservoir stimulation. In contrast, hydraulic fractures propagate more easily in high-brittleness interlayer-type oil shale. Therefore, it is recommended to prioritize the extraction of shale oil from interlayer-type oil shale reservoirs. The difference in interlayer stress is identified as the primary controlling factor for cross-layer fracture propagation in the study area. Based on the concept of geological–engineering integration, a sweet spot evaluation standard was established for the second member of the Liushagang Formation, considering both reservoir quality and engineering quality. Four sweet spot zones of interlayer-type oil shale reservoirs were identified according to this evaluation standard. To achieve uniform fracture initiation, a differentiated segment and cluster design was implemented for certain high-angle sections of well WZ11-6-5d. Interlayer-type oil shale was selected as the fracturing target, and the UFM was used for hydraulic fracture propagation simulation. Fracturing parameters were optimized with a focus on hydraulic fracture characteristics and the estimated ultimate recovery (EUR). The optimization results were as follows: a single-stage length of 50 m, cluster spacing of 15 m, pump injection rate of 10 m3/min, fluid intensity of 25 m3/m, and proppant intensity of 3.5 t/m. The application of these optimized fracturing parameters in field operations resulted in successful fracturing and the achievement of industrial oil flow.

Predictive model for shear wave velocity of gravelly soil and its application to liquefaction triggering assessment

Several studies have established empirical correlations between shear wave velocity (Vs) and standard penetration test blow count (SPT-N) for engineering use. However, these empirical correlations cannot be applied to gravel-rich soils since the measured SPT-N is often inflated in gravel. Therefore, an empirical correlation of Vs for gravel is developed in this study using the Engineering Geological Database for the Taiwan Strong Motion Instrumentation Program. The Vs predictive model considers gravel content (GC) and coefficient of uniformity (Cu) in addition to effective vertical stress, void ratio, fines content, plasticity index, and overconsolidation ratio, which have been considered previously. The proposed model indicates that Vs increases with GC and Cu. Moreover, the Vs adjusted for GC can be used with existing Vs -based liquefaction triggering relationships to rationally define the boundary between liquefaction and non-liquefaction case histories with different GCs.

Engineering Geological Complications of the Nepal Himalaya

Engineering Geological Complications of the Nepal Himalaya

Research on DFN Fracture Modeling and Fracturing Network Expansion Simulation Method for Shale Reservoirs

Abstract The degree of natural fracture formation and their link to hydraulic fracturing fractures are critical factors in production in the current large-scale fracturing development of shale gas reservoirs. Any magnitude of fractured reservoir heterogeneity may be described using the Discrete Fracture Network (DFN) model. This paper builds on earlier research by providing an additional summary of the multiscale DFN fracture modeling method, analyzing the fracture occurrence using statistical analysis techniques, analyzing the fracture scale using fractal theory, and determining the fracture development degree by combining the fracture attributes in imaging logging and three-dimensional seismic data. Different-scale fracture network models were developed. Simulating the growth of hydraulic fractures accurately using Mohr Coulomb and Barton Bandis criteria, this study also takes into account the interaction between natural and hydraulic fractures, as well as the physical properties of the rock (e.g., elastic modulus, Poisson’s ratio), closure pressure, crustal stress field, and other factors. The fracture network information, sitmulated reservoir volume, stress shadow and other attributes obtained from fracturing simulation can further analyze and evaluate the effect of fracturing simulation, and optimize the well location deployment plan and construction plan in combination with geological engineering conditions.

Research on Factors Influencing the Production of Deep Shale Gas Wells in Weiyuan Block : A Case Study of X Well on Platform A

Abstract The practice of Weiyuan deep shale gas development shows that there are many factors that affect the gas production, resulting in significant differences in gas production between wells in the same region and on the same platform. In response to the phenomenon of low gas production, low wellhead pressure, and high flowback rate in Well X on Platform A, using data from drilling, fracturing, and gas production profile testing, this study examines the impact of geological and engineering factors on gas well production through gray correlation analysis and geological engineering integrated numerical simulation methods. The results show that: ① The production of adjacent wells reduces the formation energy, resulting in a large pressure drop rate after the pump is stopped in the corresponding fracturing section of the well, poor fracturing effect and low gas production contribution; ② The order of the influence of geological factors on the gas production rate of each section is: gas content > Si content > Al content > GR value> Ca content;③The segment with natural fractures and faults contributes significantly to gas production, but its long-term effectiveness needs further evaluation. This study will provide useful references for target location optimization, fracturing design optimization, and overall development deployment of deep shale gas horizontal wells in Weiyuan.

A consistent terminology to communicate ground-related uncertainty

Engineering geology is highly affected by uncertainty related to geology, geotechnical parameters, models and methods. While the technical aspects of ground-related uncertainty are increasingly well investigated, the terminology to communicate uncertainty - e.g., “It is likely that X will happen.” - has not yet been unified and experts use it however they see fit. Due to varying experience, personal biases and societal backgrounds, people may understand uncertainty statements very differently, which is misleading and can even result in legal disputes. This contribution investigates the usage of uncertainty communicating terminology in ground-related disciplines and finds that there is a pronounced prevalence of uncertainty terminology in them. Furthermore, there is a special need to express uncertainty related to quantities (e.g. “most of the project area consists of…”). In response, we propose a framework to consistently communicate ground-related uncertainty encompassing three steps: 1. When you are certain about a statement, do not use uncertainty communicating language. 2. Assess and state the degree of confidence in a statement based on the quantity and quality of the available evidence vs. the agreement of the evidence. 3. If you have high or very high confidence in the statement, communicate the uncertainty in a consistent manner, otherwise elaborate how higher confidence can be achieved. The proposed approach feeds into new uncertainty-aware standards, such as Eurocode 7, and goes beyond them by addressing uncertainty in text and speech. This paper provides the premises for increased awareness of uncertainty communication and encourages further works on the topic.

A Study on the Implementation Path of the Blended Teaching Model in Geological Hazards Investigation and Evaluation

Geological Hazards Investigation and Evaluation is the core course of Environmental Geological Engineering, aiming to cultivate skilled talents with solid theoretical knowledge and excellent practical skills. At present, the course faces several issues, including a teaching environment disconnected from real-world work scenarios, course content that deviates from job-related tasks, a lack of digital teaching resources, and reliance on a single teaching method, leading to students’ poor feedback from employers. Based on the concept of outcome-based education, the course team of Geological Hazards Investigation and Evaluation establishes a “five-step double-rotation” blended teaching model with the help of a Small Private Online Course platform. The program is designed to improve the teaching environment and expand the digitalized teaching resources in order to improve students’ learning motivation, enhance learning effectiveness, and cultivate skillful talents who meet employers’ satisfaction.

Quantitative investigation of temperature-dependent bound water degeneration in bentonite clays

Temperature increases in saturated clay alter the physicochemical clay-water interactions and may lead to the conversion of bound water into free water. These changes significantly influence the physical, chemical, and engineering properties of clays, which are critical for geotechnical and geological engineering and minimizing risks in areas with expansive clay soils. However, quantifying this phenomenon remains challenging in the literature. This study presents a robust experimental approach for quantifying the thermal-induced conversion of bound water in clays, providing valuable insights into the mechanisms governing their thermo-mechanical behavior. A novel experimental method is proposed to quantify the degenerated bound water content in a clay system subjected to temperatures ranging from 20 to 50 °C. The research employs the siphon principle to examine volume changes in a clay system at elevated temperatures, focusing on measuring the conversion of bound water to free water. This method accounts for thermal expansion of both the soil constituents and the confining glass cylinder, as well as potential evaporation losses. To validate the setup's accuracy, a calibration test using standard Ottawa sand with negligible bound water was performed. After measuring system error, the primary outcome was calibrated. Results showed that at 30 °C, 40 °C, and 50 °C, 3 %, 9 %, and 15 % of the initial bound water, respectively, converted to free water.

R-C-D-F machine learning method to measure for geological structures in 3D point cloud of rock tunnel face

This study introduces an innovative Roughness-CANUPO-Dip-Facet (R-C-D-F) methodology for the measurement of dip angle and direction in geological rock facets. The R-C-D-F method is distinguished by its comprehensive four-step approach, encompassing filtration through roughness analysis, CANUPO analysis, and dip angle filtration, followed by facet segmentation as the measurement step. To achieve precise and efficient results, the method specifically focuses on isolating joint embedment, achieved by systematically filtering out joint bands. This selective filtration process ensures that measurements are conducted exclusively on relevant joint embedment points. The novelty of this methodology lies in its capability to automatically eliminate joint bands while retaining the joint embedment points, facilitating precise measurements without manual intervention. Three site models were evaluated using the R-C-D-F method, alongside four different techniques for measuring dip angle and direction: plane fitting, normal vector conversion, facet segmentation, and compass measurements. The results demonstrated that all methods accurately calculated the dip angle, with an accuracy ranging from 97 % to 99.4 %. The facet segmentation method was selected as the optimal measurement tool due to its automatic nature and capacity to provide accurate results without manual intervention. Furthermore, the optimal local neighbour radius (LNR) for calculating normal vectors was determined, with findings indicating that a larger LNR value enhances accuracy but also increases computational time. A verification was conducted to estimate the dip angle used for filtering and discarding additional points representing joint rock bands, with the optimal value being 45, 30, and 45 degrees for the respective sites.The R-C-D-F method effectively detected and eliminated 100 % of joint band points while retaining 81 % of joint embedment points, and the facet segmentation method provided accurate dip angle and direction measurements for each joint embedment segment. These outcomes underscore the robustness and precision of the R-C-D-F method in geological engineering and rock stability studies.

Influence of initial stresses and stress paths on the deformation and failure mechanism of sandy slate

Rocks exhibit various mechanical properties under different stress conditions, with changes during unloading having significant implications for geological engineering safety. This study carried out triaxial loading and unloading mechanical tests on sandy slate to investigate its mechanical properties, deformation characteristics, and failure mechanisms at different initial stress levels and stress paths. The results showed that during the unloading process, the deformation modulus (E) of the sandy slate decreased, and the Poisson's ratio (μ) gradually increased. This indicates that significant volume expansion of the rock is the dominant factor in its deformation and failure. The exponential function can be used to describe the evolution of E and μ with confining pressure during unloading. The damage stress of the rock under unloading conditions was lower than that under loading conditions, suggesting that unloading led to an earlier onset of volumetric expansion in the sandy slate. Under conditions where the initial axial stress level approached the damage stress, the mechanical properties were most significantly affected by unloading. Compared to loading conditions, when the initial axial stress level was at 70% of the peak strength, the cohesion (c) decreased by 15.77 to 29.37%, while the internal friction angle (φ) increased by 1.88 to 5.14%. The rock's failure process can be divided into four stages based on the development of microcracks. Unloading during the stages of microcrack initiation and propagation can lead to tensile cracks of varying degrees, resulting in different mechanical properties and failure characteristics under loading and unloading conditions.

A three-stage evaluation model for biomass co-firing combined with carbon capture and storage (in oil wells) retrofit in coal-fired power plants based on multi-criteria decision-making: An example from Hebei Province, China

Coal-fired power plants can be retrofitted by biomass co-firing combined with CO2 capture and storage, reducing carbon emissions significantly. Site selection is an important task for the entire project, but little research has been done on this. Therefore, this paper proposed a three-level evaluation model. Firstly, alternative power plants and carbon sequestration sites (set oil wells as an example) were screened by feasibility evaluations. Secondly, source-sink pairs were performed based on the shortest distance between power plants and oil wells. Finally, source-sink pairs were evaluated with suitability evaluation. Entropy weight method (EWM) and Analytic hierarchy process (AHP) were used to calculate objective and subjective weights, respectively. Lagrangian optimization method was used to combine the two weights. The ranking results of alternative source-sink pairs were obtained through Multi-Objective Optimization on the basis of Ratio Analysis (MOORA) improved by combined weight. An example of in-service power plants in Hebei Province was conducted. Engineering geology and reservoir characteristics were the most important considerations. D5 (source: Langfang thermal power plant, sink: Bieguzhuang - Jing 11 oil well) was the best choice of the five given candidates. The results of the study provided an evaluation framework for governments and investors in retrofitting power plants.