Engineering Geological Environment Research Articles

Assessing the strength of deep-sea surface ultrasoft sediments with T-bar penetration: A machine learning approach

With the expansion of marine resource utilization, geological disaster prediction, and ecological protection in deep-sea regions, accurate identification of deep-sea engineering geological environments has become paramount, highlighting the significance of understanding the mechanical characteristics of deep-sea surface ultrasoft sediments (DSUSs). However, DSUSs typically exhibit low strength, high compressibility, and significant fluidity, making sampling for indoor strength testing a challenging task. On-site testing employing a T-bar penetrometer has become increasingly prominent for assessing DSUS strength, but the complexity of influencing parameters limits the application of this valuable method. This study utilizes a validated computational fluid dynamics (CFD) approach to model the complete process of T-bar penetration into a DSUS. The aim is to understand the quantitative effects and corresponding mechanisms of various significant complex parameters, including the undrained shear strength, dimensionless penetration depth, rate effect, and interface contact condition, on the dimensionless penetration resistance coefficient. Additionally, a machine learning model based on the random forest algorithm is introduced to establish a multiparameter evaluation method for the dimensionless penetration resistance coefficient. The findings illuminate the intricate interactions and effective evaluation of these factors when evaluating DSUS strength using a T-bar penetrometer, addressing the above challenges in marine engineering geology and the environment.

Risk zonation of submarine geological hazards in the Chengdao area of the Yellow River subaqueous delta

Submarine geological disasters occur frequently in the Chengdao area of the Yellow River subaqueous delta, which seriously threaten the safe operation of marine engineering in the region. Therefore, it is of great significance to carry out risk zonation for this region. The current study presents a detailed assessment of risk zones related to submarine geological hazards in this region based on analytical hierarchy process (AHP). The system of assessment index for risk zonation was established with four aspects of hydrodynamic condition, engineering geological environment, disaster geological conditions and human engineering activities. Eight geological hazard evaluation factors were selected and the distribution characteristics of each evaluation factor were discussed in detail by combining qualitative analysis and quantitative calculation. The risk level of submarine geological hazards in the Chengdao area are divided into four types: low risk, relatively low risk, relatively high risk, and high risk. The results show that the areas with a high geological hazard risk in this region are mainly distributed in the areas with water depths of 9–12 m, where the hydrodynamic effect is strong, with many human engineering activities, and seriously suffered from geologic hazards. The study results can provide scientific basis for engineering construction and hazard prevention in the Chengdao area.

Robust model for tunnel squeezing using Bayesian optimized classifiers with partially missing database

Accurately predicting and estimating the squeezing and ground response to tunneling remains challenging. Moreover, tunnel-squeezing hazards are much more likely to occur in deeply buried long tunnels with complex engineering-geological environments. Therefore, a high-performance predictive model for tunnel squeezing is necessary. A superior ensemble classifier is put forward in this study, which is composed of four individual classifiers (gradient boosting classifier, extra-trees classifier, AdaBoost classifier, and Logistic regression classifier) and two optimization algorithms (Bayesian optimization (BO) and sparrow search algorithm (SSA)). The training database covers five parameters: tunnel depth (H), rock tunneling quality index (Q), tunnel diameter (D), support stiffness (K), and strength stress ratio (SSR), about which the basic information is accessible at the early design phases. However, the dataset compiled from the literature is insufficient. Thus, the ten proposed methods are used to replace the missing values. During the model training process, BO shows its strong ability to optimize seventeen hyperparameters. When applied to tune the classifiers' weights, SSA achieves a fast and efficient performance. The novel Shapley Additive Explanations–LightGBM method indicates that the K is the most important input feature, followed by SSR, Q, H, and D, respectively. The ensemble classifier is then validated using the test set and additional historical case projects. The validation shows that the model can achieve an accuracy of 98% (i.e., the error rate is 2%) on the test set, higher than those achieved by previous prediction models. Moreover, the predicted probability could provide warning information for timely support measures. Finally, the application results are illustrated through tests on the tunnel sections that have not yet been excavated in the line of the Sichuan–Tibet railway project. The applied predictive tendencies and laws are in line with the practical experience. In summary, the proposed model's prediction results are reasonable, and its prediction will be more accurate as more data is collected and trained for prewarning the tunnel squeezing hazard.

Investigation on the influence of the Bohai Sea Geological Environment on the submarine stratum stability based on data mining: an intelligent prediction model.

The Bohai Sea has unique characteristics of the marine geological environment, with strong water closure and weak self-purification ability. Assessment of the submarine stratum stability plays an essential part in ocean engineering construction, preventing marine geological disasters and controlling environmental pollution for the Bohai strait. Nevertheless, limited studies have investigated quantitative classification of the submarine stratum stability or the influence of Bohai Sea's engineering geological environment on the submarine stratum stability using laboratory experiments and the data mining method. Thus, this study carried out physical and mechanical experiments based on the submarine borehole soil samples from the Bohai Sea. And a database containing 60 groups of submarine soil samples' mechanical parameters was established. The physical and mechanical parameters of the Bohai sea's submarine soil, i.e., depth, water content, void ratio, density, internal friction angle, and cohesion, are the prediction indicators. And the submarine soil samples' unconfined compressive strength and elastic modulus are used for quantifying the stability grade of Bohai Sea's submarine stratum. Furthermore, the submarine stratum stability prediction model was established based on the multiple linear regression analysis method and the nonlinear regression analysis method (i.e., BPNN, normal cloud, and TOPSIS method). The testing results indicate that the submarine stratum stability prediction model obtained by the linear regression analysis does not have obvious linear characteristics and gives a poor prediction performance (MAE=0.9333, MAPE=0.3, RMSE=1.2111). In contrast, the nonlinear analysis methods presented a higher fitting version. Compared to the cloud model and the TOPSIS method, the BPNN model with the lowest testing error (MAE=0.2, MAPE=0.1, RMSE=0.4472) presented the best prediction accuracy. The proposed submarine stratum prediction model has been validated as an effective submarine stratum stability prediction method and has good prospects for further ocean engineering applications.

Study on the Water Conservancy Engineering Geological Survey and Engineering Geological Environment

Study on the Water Conservancy Engineering Geological Survey and Engineering Geological Environment

Failure Mode and the Prevention and Control Technology of Buried PE Pipeline in Service: State of the Art and Perspectives

Material defects and external environmental factors increase the engineering safety risks of buried PE pipelines in service. This paper mainly reviews the failure mode and the prevention and control technology of buried PE pipelines in service, as well as comparative failure characteristics between the buried PE and steel pipelines. The main failure factors of buried PE pipelines can be divided into four levels: the first level is third‐party damage; the second level includes three failure factors, i.e., surface subsidence, joint failure, and aging failure; the third level consists of pipe piercing, crack development, and pipeline defect; the fourth level is a corrosion failure. Besides, steel and PE pipelines have various physical and mechanical properties, which lead to a significant difference in the service performance and degradation mechanism in practice. For instance, corrosion and welded joint leakage are the two common problems in steel pipelines during the service period, while PE pipelines have excellent corrosion resistance. Additionally, in order to ensure and maintain the long‐term operations of PE pipelines, it is of great significance to develop and promote nonexcavation technologies of construction, renewal, and repair for natural gas‐buried PE pipelines. Furthermore, based on the above studies, some further research studies on buried PE pipelines in service are suggested and discussed, e.g., (a) the service performance and degradation mechanism of buried PE pipelines in complicated environmental conditions, (b) the interaction mechanism among the engineering structure, PE pipelines, and geological environment, as well as PE pipeline geological soils coupled in multiple physical fields, and (c) the combinations of the traditional engineering risk assessment method and the numerical analysis method considering the interaction between the PE pipeline and geological environment. The results could be helpful for a better understanding of the operation conditions of buried PE pipelines, and it is also hoped that this study could provide guidance for the safe operation, maintenance, and integrity management of buried PE pipelines.

Construction of evaluation system and evaluation model of urban environmental engineering geological problems —— a case study of Jinan City

In order to further study the problems of urban engineering geological environment, taking Jinan as an example, the environmental engineering geological problems are divided into four aspects: primary environmental engineering geological problems, secondary environmental engineering geological problems, the influence of human activities and the restriction of spring water on engineering construction. A multi-level, multi-objective and multi factor evaluation index system suitable for environmental engineering geology is established. The mathematical model is established by using analytic hierarchy process and fuzzy comprehensive evaluation method to evaluate the primary environmental engineering geological problems, secondary environmental engineering geological problems, the impact of human activities and the restrictive effect of spring water on engineering construction. The mathematical model is established by using Nemero index method to comprehensively evaluate the environmental engineering geological problems in Jinan, and the suitability zoning of engineering construction is carried out.

A three-dimensional intelligent engineering management and control system for the construction of a long-span valve hall project based on a microservice architecture.

Three-dimensional intelligent engineering management and control systems (EMCS) based on the browser/server (B/S) model are an important part of intelligent engineering development. These systems are used for solving the difficulties encountered in engineering management with frequent cross-specialties and are vital tools for data exchange and service sharing among multiple departments. Currently, most engineering management and control systems are based on service-oriented architectures (SOAs). The integration mechanism and high coupling of SOAs leads to the reduction in system expansibility, service quality and service safety of the engineering system, making it difficult for these architectures to serve the construction of long-span valve hall engineering. To address these concerns, the management and application technology of the multidisciplinary data of valve hall engineering based on a microservice architecture (MSA) is proposed to improve the management efficiency of engineering data. A 3D integration modeling method for valve hall engineering structures and geological environments is proposed to establish the topological association between engineering structures and geological environments, without increasing the amount of model data required. A 3D intelligent engineering management and control technology for the entire process of the construction of long-span valve hall engineering is proposed, which realizes the entire process simulation and control of engineering construction based on WebGL technology. Accordingly, a three-dimensional intelligent engineering management and control system for the entire construction process of a long-span valve hall project in Southeast China is established, which can effectively manage and apply the data, display and analyze the three-dimensional model, and control and make decisions regarding the construction schedule. This study provides support for the construction of "smart engineering", promotes information communication and transmission between different project units, and speeds up the transformation from traditional construction management relying on drawings to three-dimensional intelligent construction management based on cloud services.

Suitability of Engineering-Geological Environment on the Basis of Its Permeability Coefficient: Four Case Studies of Fine-Grained Soils.

The aim of the article is to compare two classifications systems of engineering-geological environment sustainability in terms of its permeability evaluated on the basis of permeability coefficient. The first evaluated classification assumes a permeable environment to be a positive characteristic in the engineering-geological assessment, while the other considers an impermeable environment as favourable. The four fine-grained soil materials were selected, as they had very similar, almost identical grains-size distribution, but different microstructure characterized by grains sphericity, angularity, and roughness. At the same time, the influence of changes in the density of soil materials (density index 10%, 30%, 60%, 90%) was analysed. Permeability coefficient was determined using six methods (empirical formulae, laboratory and microscopic analysis). The laboratory method falling head test (FHT) was taken as a reference test that reflected the actual water flow through the soil. It was found that with an increase in grain angularity and roughness (and a decrease in sphericity), the permeability coefficient was decreasing and this trend culminated along with gradual compaction. Moreover, the research shows that unsuitable methods may classify soil materials into wrong engineering-geological permeability classes, which may have negative consequences during engineering-geological or geotechnical assessment and cause subsequent problems in foundation engineering.

Construction Engineering Geological Survey and Engineering Geological Environment Based on "Green Building Concept"

Construction Engineering Geological Survey and Engineering Geological Environment Based on "Green Building Concept"

Investigation of permafrost engineering geological environment with electrical resistivity tomography: A case study along the China-Russia crude oil pipelines

The electrical resistivity tomography and vegetation surveys were conducted for investigating the distribution of frozen ground and other engineering geological characteristics at four representative sites (BHP, XFB, WLG, and XAZ) along the China-Russia Crude Oil Pipelines (CRCOPs) I and II. The comprehensive analysis shows that CRCOPs play an important role in forming and connecting supra-permafrost subaerial taliks and in facilitating thermokarst landforms, further accelerating permafrost degradation. The survey results indicate that on 15–29 August 2019, the permafrost base under the CRCOP at the XFB site was 21.5 m in depth, that of WLG site was 21.5 m (32.8 m at the undisturbed sites), and that of XAZ site, 37.3 m; the permafrost table of XFB site was 6.72 m (4.97 m on 20 m away from the pipeline), that of WLG site was 8.64 m (1.94 m at the undisturbed sites), and that of XAZ site was 6.72 and 3.38 m on the southern and northern slopes; the hydrothermal influences of CRCOPs extended horizontally to about 60 m away from the pipelines, but the vertical hydrothermal impacts were largely limited to about 10–15 m in depth at the BHP site in the zone of deep (>1.5 m) seasonal frost. The extent of engineering influences from the pipelines and associated engineering activities in patchy and island permafrost are evidently larger than those in seasonal frost. The sites with substantial changes are found in pipeline foundation soils underlain by warm (> − 1 °C; thermally unstable) and ice-rich permafrost. This study can timely help decision makers mitigate frost hazards in a proactive manner.

Laboratory Experiments and Grain Based Discrete Element Numerical Simulations Investigating the Thermo-Mechanical Behaviour of Sandstone

Thermo-mechanical loading can occur in numerous engineering geological environments, from both natural and anthropogenic sources. Different minerals and micro-defects in rock cause heterogeneity at a grain scale, affecting the mechanical and thermal properties of the material. Changes in strength and stiffness can occur from exposure to elevated temperatures, with the accumulation of localised stresses resulting in thermally induced micro-cracking within the rock. In this study we investigated thermal micro-cracking at a grain scale through both laboratory experiments and their numerical simulations. We performed laboratory triaxial experiments on specimens of fine-grained sandstone at a confining pressure of 5 MPa and room temperature (20^{circ }hbox {C}), as well as heating to 50^{circ }hbox {C}, 75^{circ }hbox {C} and 100^{circ }hbox {C} prior to mechanical loading. The laboratory experiments were then replicated using discrete element method simulations. The geometry and granular structure of the sandstone was replicated using a Voronoi tessellation scheme to produce a grain based model. Strength and stiffness properties of the Voronoi contacts were calibrated to the laboratory specimens. Grain scale thermal properties were applied to the grain based models according to mineral percentages obtained from quantitative X-ray diffraction analysis on laboratory specimens. Thermo-mechanically coupled modelling was then undertaken to reproduce the thermal loading rates used in the laboratory, before applying a mechanical load in the models until failure. Laboratory results show a reduction of up to 15% peak strength with increasing thermal loading between room temperature and 100^{circ }hbox {C}, and micro-structural analysis shows the development of thermally induced micro-cracking in laboratory specimens. The mechanical numerical simulations calibrate well with the laboratory results, and introducing coupled thermal loading to the simulations shows the development of localised stresses within the models, leading to the formation of thermally induced micro-cracks and strength reduction upon mechanical loading.

Critical Conditions and Energy Transfer Characteristics of the Failure Process of Coal-Rock Combination Systems in Deep Mines

With the steady increase in the size, intensification, and modernization of coal production enterprises, the deep coal resources in large coal bases are gradually entering the mining stage. When the coal mining reaches the deep zone, the interactions between various underground dynamic hazards begin to occur. These interactions are affected by the engineering geological environment and can lead to the occurrence of severe compound hazards. When coal and gas outbursts occur and destabilize the mining area, the high geostress causes the multiphysical coupling effect of the laminated overburden system to become more pronounced. Therefore, we analyzed the development path of a coal-rock system under instability conditions from the perspective of coal–rock coupling, constructed a model of the coal-rock combination system’s structure, and proposed three directions (i.e., strain softening, limit equilibrium, and dynamic instability) for the development of coal-rock system instability. Then, we established a model for the critical conditions of the system’s failure process and elucidated that the release of the rock’s elastic energy promoted the instability of the coal. Furthermore, we verified the established critical conditions through laboratory tests on a coal-rock combination structure and obtained the patterns of the rock energy transferring into the coal seam during the instability failure process of the coal–rock combination structure. When the coal–rock combination structure failed, the rock strain reached its maximum value and the strain rebound phenomenon occurred. The stored elastic strain energy released by the rock into the combination system accounted for 26% to 53% of the accumulated energy in the rock itself, and the released elastic energy and the new surface area of the crushed coal sample followed a logarithmic relationship. The findings of this study provide theoretical support for the identification and quantitative analysis of instability due to the dynamic hazards of coal-rock gas in deep mines.

Investigation of overburden failure characteristics due to combined mining: case study, Henan Province, China

The evolution of fractures in overburden is quantitatively investigated to characterize the effect of mining activity. Scale model testing and numerical modeling were used based on the engineering geological and mining environments of Panel 11050 in the Quandian Coalmine in Henan Province, China. The maximum vertical displacement is 62.76 m, which is 140 m from the initial mining in the scale model test. Based on the fractal geometric theory, the fractal dimensions of the fractures in the overburden are calculated and visualized. The results reveal that if two coal seams are mined at the same time, the fractal dimension of the fracture network in the overburden increase with the progression of mining, but the rate of increase gradually slows. The relationships between the fractal dimension and the maximum height of the overburden failure and maximum overburden subsidence are nonlinear. The structural characteristics of the overburden are represented by the network of fractures. With increasing distance from the coal seam roof, the mining stress is gradually transferred upward to the overlying strata, and the scale of this stress transfer gradually reduces. The variation in the vertical stress gradually weakens and shows a delayed change with the mining process. The maximum principal stress is compressive stress and is distributed in an “arch” shape. The stress on both sides of the “arch” is high, and the intermediate stress is low. The stress within the “arch” shows an opposite trend.

Research on Construction of Industrial Environment System of Cross-border E-commerce in Free Trade Zone Based on Geological Environment Assessment Method

Based on the regional engineering geological environment conditions, the thesis divides the engineering geological environment evaluation types into single-element evaluation and comprehensive evaluation, and uses analytic hierarchy process and fuzzy mathematical model to carry out comprehensive evaluation of engineering geological environment. On the basis of single-element evaluation, comprehensively analyze the factors that affect the stability of the site, the factors that determine the stability of the foundation, the degree of groundwater impact, and the factors of the drainage conditions of the site. In order to conduct a comprehensive analysis. Finally, combined with the results of single factor evaluation and comprehensive evaluation, it analyses it impact on the cross-border e-commerce industrial environment of the free trade zone.

Study on the Method of Constructing Engineering Geological Three-dimensional Model of Hydrate Area in South China Sea Based on ArcGIS

The trial production of marine natural gas hydrates (NGH) in China is gradually increasing, attracting concerns on related environmental issues. The entire regional conditions of engineering geological environment must be investigated thoroughly before NGH production. These conditions should be defined, among others, in terms of seabed topography, stratigraphic structure, soil types, physical and mechanical characteristics, hazardous geological factors and distributions, and hydrodynamic characteristics, which provide a variety of geological spatial information and can be obtained from different sources. Due to the high cost and low efficiency of deep-sea engineering geological drilling, only few stations can be deployed. Hence, not enough data are available for the construction three-dimensional (3D) geological models. This study considered the data of only a few drilling stations and compared them with well logging and 3D seismic data. First, the engineering geological standard strata were established. Second, we interpreted and exported the stratigraphic (based on virtual boreholes) and spatial information (in terms of X, Y, and Z) of existent geological structures in GeoFrame. Finally, using several technical modules of ArcGIS (i.e., ArcMap, ArcScene, ArcCatalog), we constructed a spatial database and a comprehensively intuitive 3D visualization data management platform for engineering geological environmental surveys and evaluations in the hydrate area. By clicking any element included in the platform, the correspondent data or results can be looked over: this efficient and continuous systematic database can be used to support the future production of NGH in the area.

Research on the strategy of optimizing the discipline layout of environmental geosciences under the National Natural Science Foundation of China

Optimizing the discipline layout is an important task for deepening the reform of National Natural Science Foundation of China. The discipline of environmental geosciences (DEG) has a short history and is not perfect in the discipline layout and system framework. The DEG takes the opportunity of optimizing the discipline layout and proactively responses to the top-level strategy of “Habitable Earth-Earth System Science”, initiated by the Department of Earth Sciences. Based on a wide range of strategic research, the establishment background of DEG was reviewed, and the challenges of DEG in terms of research objects, theoretical systems, technical methods, and research paradigms were analyzed. The overall concept of optimizing the discipline layout of DEG was clarified, namely basic disciplines, interdisciplinary disciplines, cutting-edge fields, new technologies and methods, and national needs. Based on the overall concept of the discipline layout, the discipline framework of “four beams and eight pillars” was established. Four basic disciplines constitute the “four beams”: Soil science (D0701), environmental water science (D0702), environmental atmospheric science (D0703) and environmental biology (D0704). Four interdisciplinary disciplines and four cutting-edge fields together constitute the “eight pillars”. The four interdisciplinary disciplines include engineering geological environment and disaster (D0705), environmental geology (D0706), environmental geochemistry (D0707) and ecotoxicology (D0708). The four cutting-edge fields are environmental pollutant behavior and environmental effects (D0709), environment and health risks (D0710), quaternary environment (D0711), environmental information and environment forecast (D0712). New technologies and methods of DEG (D0713) are the support of the discipline. Regional environmental quality and safety (D0714) and environmental protection and sustainable development (D0715) are the major objectives of DEG to serve national needs. Combining the characteristics and advantages of DEG to serve national needs, the connotation of DEG is defined as pollution environment, ecological environment, disaster environment and healthy environment. The existing problems of the discipline application codes were identified, including incomplete code system, unsmooth logical relationship between codes, and unbalanced code level and size. The preliminary adjustment proposals for the application codes were put forward. This study is for related researchers to discuss and promote the high-quality development of DEG.

Karst geology and mitigation measures for hazards during metro system construction in Wuhan, China

Karst geology is widely distributed in China; the great differences in natural conditions bring it an array of characteristics in different regions. There is a huge area of the buried karst in Wuhan, exhibiting a unique, but complicated engineering geological environment. This paper summarizes the geological conditions in Wuhan, with special focus on its karst geology. At present, a total of six karst belts have been detected, and they were divided into five structure types. For shield tunnelling in karst region, some problems such as water ingress or mud inrush, partial ground collapse, damage or failure of shield machine, and metro operation and management issues may be raised as a result of the activity of the karst geology. To prevent occurrence of possible hazards, a series of countermeasures suggested for hazard and risk mitigation were discussed in this paper. A case history, where the study section belongs to the Wuhan metro line 6, is referred to evaluate effectiveness of the adopted treatment measures. The feedbacks demonstrated that water ingress was successfully avoided, and ground deformation was effectively controlled in the study section throughout the construction phase. This study can provide significant reference information and experience for metro tunnel constructed in karst region.

Study on the shear deformation of intralayer shear bands at the Baihetan hydropower station dam foundation

The engineering geological environments of the Baihetan hydropower station dam site are complicated due to the existence of columnar jointed basalt with faults and intralayer shear band structures. In the excavation process of the left dam foundation, relaxation and deformation of the columnar jointed basalt and the unloading shear deformation of the intralayer shear bands are both important engineering geological problems. Taking a typical intralayer shear band exposed during the excavation of the left dam foundation of the Baihetan hydropower station as an example, the unloading shear deformation of the intralayer shear band was investigated by in situ testing and numerical analysis in this study. The results confirmed that the unloading shear deformation of the intralayer shear bands can present an instability risk for the left dam foundation due to their poor mechanical strength and shearing damage. Therefore, a reinforcement measure of intralayer shear bands is critical for the stability assessment of similar structures.

Dynamic Risk Analysis in Metro Construction Using Statistical Process Control

Metro construction is normally carried out in complex engineering geological environment, so it can generate various risk events. In the process of metro construction, a scientific risk dynamic analysis is indispensable to reduce and control risks. In order to analyze the risk in metro construction more scientifically and reasonably, in this study, a new risk dynamic analysis method for metro construction is proposed using statistical process control. The method can analyse the risk level according to the process’s capacity index and identify the characteristics of risk variation according to the statistical control chart. The risk level and the characteristic of risks may vary with dynamical updating of monitoring data, so the conclusion of risk evaluation for a time interval can be drawn and corresponding safety measures can be ascertained. The method ushers statistical process control, so the random factors in risk evolution can be considered fully. Then, the method is applied to the risk analysis of shield construction under the Beijing-Tianjin intercity railway in Beijing Metro Line 8, a typical risk problem in the traffic construction. The variation of the risk level and the characteristic of risks can be evaluated reasonably because the dynamical randomness is considered. Moreover, whether risk control measures should be taken and what the effective measures are can be ascertained explicitly.