Hasil untuk "Engineering geology. Rock mechanics. Soil mechanics. Underground construction"

Yazhen Sun, Longyan Wang, Jinchang Wang et al.

This study aims to systematically investigate the coupling effects of in situ stress, joints and free surfaces on rock blasting damage. By determining tuff-specific Riedel‒Hiermaier‒Thoma (RHT) constitutive parameters via split Hopkinson pressure bar (SHPB) tests and employing a smoothed particle hydrodynamics–finite element method (SPH-FEM) model in LS-DYNA, it reveals how these factors collectively control damage zone distribution, crack propagation and ejection behavior. The findings provide a theoretical basis for optimizing blasting design in high in situ stress and jointed rock masses. This research employs an integrated methodology: First, tuff-specific RHT constitutive parameters were determined via SHPB tests and theoretical calibration. Subsequently, a 3D blasting model was developed using the SPH-FEM coupled approach on the LS-DYNA platform. This model systematically simulated the individual and coupled effects of in situ stress, joints and free surfaces. The approach combined experimental parameter determination with advanced numerical modeling to quantitatively analyze damage mechanisms and ejection behavior. This study reveals that in situ stress type dictates blasting damage patterns: hydrostatic fields suppress cracks but enhance crushing, while non-hydrostatic fields cause directional damage. Joints create asymmetric cracks and energy concentration, interacting with in situ stress to expand the crushing zone. Free surfaces control crushing scale via wave reflection, dynamically interacting with in situ stress redistribution. Parameter sensitivity analysis identifies Fs* as most critical for stress and damage. These findings provide mechanisms for precise blasting control in complex geological conditions. (1) Simplified representation of complex joint networks and rock heterogeneity in the model. (2) Assumed linear elastic behavior for intact rock segments prior to failure. Based on the findings, this study proposes targeted blasting strategies: For hydrostatic stress fields, increase charge to overcome confinement; for non-hydrostatic fields, align the minimum resistance line with the maximum principal stress. Implement stress relief holes and directional blasting in jointed rock masses. Apply millisecond initiation to optimize the “free surface-stress-energy” mechanism. These approaches enable precise control of damage and ejection trajectories, providing practical guidance for tunnel blasting in high-stress strata, jointed rock masses and multi-free surface conditions. This research enhances blasting safety and efficiency in underground construction and mining, directly benefiting infrastructure development and resource extraction. By enabling precise damage control, it reduces geological hazards, minimizes support costs and improves operational safety for personnel. The optimized techniques contribute to more sustainable rock excavation by lowering energy consumption and environmental disturbance. Ultimately, the study supports safer, more economical and more environmentally responsible engineering practices in geotechnically complex projects. This study's originality lies in systematically revealing the coupling mechanisms of in situ stress, joints and free surfaces on rock blasting. It provides novel insights into their synergistic control over damage distribution and ejection behavior. The value is demonstrated through determining tuff-specific RHT parameters and establishing a reliable SPH-FEM model. These findings enable precise blasting control in complex geology, offering practical strategies for optimized design in tunneling and mining, ultimately advancing both theoretical understanding and engineering practice in rock blasting mechanics.

Hao Wang, Hailong Wang, Hideo Komine et al.

This paper presents a method for obtaining the displacement of sand particles in a sand–bentonite mixture (SBM) when saturated with water, based on particle tracking velocimetry (PTV). The raw photographs were first converted into binary images. The sand particles were then detected, and the displacement of the sand particles was obtained by comparing their positions in adjacent images. The swelling strain induced by saturation was also obtained using the proposed PTV method. This method was validated by comparing the result with those obtained using a displacement transducer. Subsequently, a comparative analysis of sand particle displacements was conducted for specimens with varying bentonite content (BC), initial thickness, and water infiltration directions. The experimental results obtained were as follows: (1) For specimens with different BCs, local swelling displacement of sand particles at the top part of the specimen increased with higher BCs; (2) For specimens with various heights (hsp), larger local swelling displacement was generated at lower hsp at the initial state; (3) Local swelling characteristics differed in different water infiltration directions. Top-side infiltration showed a significant downward movement of particles during the first several hours of swelling. An estimation method for the dry density distribution of the specimen was proposed based on PTV data and then verified by slicing dry density and water content measurement results.

Yunpeng Zhang, Hongxuan Ji, Lulu Zhang et al.

The torsional low strain integrity test (TLSIT), known for its advantages such as a smaller detection blind zone, improved identification of shallowly buried defects, stable phase velocity for signal interpretation, and better adaptability for existing pile testing. However, it lacks a comprehensive understanding of the authentic three-dimensional (3D) strain wave propagation mechanism, particularly wave reflection and transmission at defects. To address this gap, a novel 3D theoretical framework is introduced in this context to model the authentic 3D wave propagation during the TLSIT. The proposed approach is validated by comparing its results with those obtained from 3D finite element method (FEM) simulations and simplified 1D (one-dimensional) and 3D analytical solutions. Additionally, a parametric study is conducted to enhance insights into the formation mechanism of high-frequency interference observed during the TLSIT. Finally, a defect identification study is performed to provide guidance for interpreting the wave spectrum in terms of defect characteristics.

WANG Tao1, 2, 3, 4 , FAN Hong2, 4, WANG Kangren2, 4, ZHOU Guoqing1, 3, WANG Liangliang1

The constitutive model for warm frozen soil is crucial for accurately calculating the stress and deformation of frozen soil layers. Based on the modified Cambridge model and the dual-yield surface theory, taking into account the influences of cohesion and internal friction angle of warm frozen soil, the deformation characteristics of the specimens are described by the overall deformation curve εv-lnp. The hardening parameters of the current yield surface and reference yield surface are modified by stress path correlation factors. A unified constitutive model of dual-yield surface for warm frozen soil is proposed. The incremental form of the stress-strain relationship is obtained based on the elastic-plastic theory. A convenient method for determining the model parameters is provided. The consolidation parameters and potential strength parameters that reflect the current state of warm frozen soil are defined. An analysis of the dynamic cyclic relationship and interdependence between these parameters and hardening parameters is presented. The experimental data are used to validate the constructed constitutive model, and the results show that the proposed model can accurately predict the stress-strain behavior of warm frozen soil under conventional triaxial stress conditions.

Kun-Peng Li, Yong-Gui Chen, Yu-Cheng Li et al.

Deep geological repository is typically situated at depths ranging from several hundred to 1000 m below ground, making bentonite engineered barrier potentially vulnerable to high water pressure and even inducing hydraulic fracturing. This study conducted injection tests on compacted GMZ (Gaomiaozi) bentonite with a self-developed visualization set-up. The objective was to unveil the roles of dry density, water content, and pressurization rate in hydraulic fracturing from the perspective of fracturing macro-morphological dynamics and breakthrough characteristics. Moreover, the relationships between breakthrough characteristics and microstructure were examined by MIP (mercury intrusion porosimetry) analysis. Results showed that the fracturing dynamics were characterized by three stages: hydration, cracking, and fracturing stages. Compared to water content and pressurization rate, dry density exerted more pronounced effects on these stages. Increasing dry density can lead to an expansion of circular hydration zone, a more complex cracking network, and a change in fracturing patterns from long and clear to short and fuzzy. In terms of breakthrough characteristics, the breakthrough pressure was positively correlated with dry density and negatively correlated with water content. Interestingly, there is a good and unique logarithmic correlation between the breakthrough pressure and the ratio eM/em of inter-aggregate void ratio and intra-aggregate void ratio, regardless of dry density and water content. Within a certain range (i.e. 200-50 kPa/min), breakthrough pressure showed slight dependency on pressurization rate. Nevertheless, an extremely low pressurization rate of 20 kPa/min caused a transition for the specimen from quasi-brittle to plastic state owning to more water infiltration, thereby hindering fracture initiation and propagation.

Arvind W Kiwelekar

Quantum mechanics, the fundamental theory that governs the behaviour of matter and energy at microscopic scales, forms the foundation of quantum computing and quantum information science. As quantum technologies progress, software engineers must develop a conceptual understanding of quantum mechanics to grasp its implications for computing. This article focuses on fundamental quantum mechanics principles for software engineers, including wave-particle duality, superposition, entanglement, quantum states, and quantum measurement. Unlike traditional physics-oriented discussions, this article focuses on computational perspectives, assisting software professionals in bridging the gap between classical computing and emerging quantum paradigms.

Tomi Suomi, Petri Ihantola, Tommi Mikkonen et al.

Agile software development relies on self-organized teams, underlining the importance of individual responsibility. How developers take responsibility and build ownership are influenced by external factors such as architecture and development methods. This paper examines the existing literature on ownership in software engineering and in psychology, and argues that a more comprehensive view of ownership in software engineering has a great potential in improving software team's work. Initial positions on the issue are offered for discussion and to lay foundations for further research.

LI Yifan 1, 2, LI Dayong 3, ZHANG Yukun 2

The steel piles and steel suction caissons are widely used in ocean engineering, in which the mechanical behaviors of the interface between soils and foundations determine their bearing capacities. A series of saturated sand–steel interface drained shear tests are conducted to reveal the effects of the grain size distribution, surface texture and normal confinement conditions on interfacial shear behaviors. The research shows that due to the differences in the shear mode of sand particles and the dissipation of the pore water pressure, the shear stress-displacement curve under a constant normal load (CNL) experiences an obvious strain-softening phenomenon, whereas the maximum shear stress increases with the increase of the normal stress increment under a variable normal load (VNL). For the smooth and convex surfaces, the interfacial friction angle increases linearly with the increase of Cu. For the groove surfaces, the interfacial friction angle decreases with the increase of Cu. The shear efficiency of the saturated sand-steel plate interface is greatly influenced by water, and the presence of the water film weakens the friction between sand particles and steel plates, thus, the maximum efficiency cannot be developed on interfaces.

Dipen Bista, Adrian Ulfberg, Leif Lia et al.

When assessing the sliding stability of a concrete dam, the influence of large-scale asperities in the sliding plane is often ignored due to limitations of the analytical rigid body assessment methods provided by current dam assessment guidelines. However, these asperities can potentially improve the load capacity of a concrete dam in terms of sliding stability. Although their influence in a sliding plane has been thoroughly studied for direct shear, their influence under eccentric loading, as in the case of dams, is unknown. This paper presents the results of a parametric study that used finite element analysis (FEA) to investigate the influence of large-scale asperities on the load capacity of small buttress dams. By varying the inclination and location of an asperity located in the concrete-rock interface along with the strength of the rock foundation material, transitions between different failure modes and correlations between the load capacity and the varied parameters were observed. The results indicated that the inclination of the asperity had a significant impact on the failure mode. When the inclination was 30° and greater, interlocking occurred between the dam and foundation and the governing failure modes were either rupture of the dam body or asperity. When the asperity inclination was significant enough to provide interlocking, the load capacity of the dam was impacted by the strength of the rock in the foundation through influencing the load capacity of the asperity. The location of the asperity along the concrete-rock interface did not affect the failure mode, except for when the asperity was located at the toe of the dam, but had an influence on the load capacity when the failure occurred by rupture of the buttress or by sliding. By accounting for a single large-scale asperity in the concrete-rock interface of the analysed dam, a horizontal load capacity increase of 30%–160% was obtained, depending on the inclination and location of the asperity and the strength of the foundation material.

José Neves, João Moutinho, Ana Cristina Freire et al.

O artigo apresenta uma compilação de exemplos nacionais de investigação, desenvolvimento e inovação relacionados com a transição verde e a transformação digital no âmbito da geotecnia nos transportes e associados às terraplenagens, pavimentos e vias-férreas. No âmbito da transição verde, são apresentados exemplos de aplicação de materiais não convencionais e renováveis e de técnicas de estabilização baseadas na ativação alcalina de excedentes industriais. Em relação à transformação digital, são descritos desenvolvimentos com aplicação às terraplenagens, aos pavimentos rodoviários e à via-férrea (morfologia das partículas de agregado de balastro). Os exemplos apresentados no artigo demonstram a capacidade geotécnica que as empresas e as instituições do sistema científico e tecnológico em Portugal têm para o cumprimento das metas estabelecidas para a sustentabilidade e resiliência no setor das infraestruturas de transporte.

Xia Bian, Zhuyi Fan, Jiaxing Liu et al.

This paper presents a regional 3D geological modeling method based on the stacking ensemble technique to overcome the challenges of sparse borehole data in large-scale linear underground projects. The proposed method transforms the 3D geological modeling problem into a stratigraphic property classification problem within a subsurface space grid cell framework. Borehole data is pre-processed and trained using stacking method with five different machine learning algorithms. The resulting modelled regional cells are then classified, forming a regional 3D grid geological model. A case study for an area of 324 km2 along Xuzhou metro lines is presented to demonstrate the effectiveness of the proposed model. The study shows an overall prediction accuracy of 85.4%. However, the accuracy for key stratigraphy layers influencing the construction risk, such as karst carve strata, is only 4.3% due to the limited borehole data. To address this issue, an oversampling technique based on the synthetic minority oversampling technique (SMOTE) algorithm is proposed. This technique effectively increases the number of sparse stratigraphic samples and significantly improves the prediction accuracy for karst caves to 65.4%. Additionally, this study analyzes the impact of sampling distance on model accuracy. It is found that a lower sampling interval results in higher prediction accuracy, but also increases computational resources and time costs. Therefore, in this study, an optimal sampling distance of 1 m is chosen to balance prediction accuracy and computation cost. Furthermore, the number of geological strata is found to have a negative effect on prediction accuracy. To mitigate this, it is recommended to merge less significant stratigraphy layers, reducing computation time. For key strata layers, such as karst caves, which have a significant impact on construction risk, further on-site sampling or oversampling using the SMOTE technique is recommended.

Haibo Hu, Xunjian Hu, Xiaonan Gong

The application of steel strut force servo systems in deep excavation engineering is not widespread, and there is a notable scarcity of in-situ measured datasets. This presents a significant research gap in the field. Addressing this, our study introduces a valuable dataset and application scenarios, serving as a reference point for future research. The main objective of this study is to use machine learning (ML) methods for accurately predicting strut forces in steel supporting structures, a crucial aspect for the safety and stability of deep excavation projects. We employed five different ML methods: radial basis function neural network (RBFNN), back propagation neural network (BPNN), K-Nearest Neighbor (KNN), support vector machine (SVM), and random forest (RF), utilizing a dataset of 2208 measured points. These points included one output parameter (strut forces) and seven input parameters (vertical position of strut, plane position of strut, time, temperature, unit weight, cohesion, and internal frictional angle). The effectiveness of these methods was assessed using root mean square error (RMSE), correlation coefficient (R), and mean absolute error (MAE). Our findings indicate that the BPNN method outperforms others, with RMSE, R, and MAE values of 72.1 kN, 0.9931, and 57.4 kN, respectively, on the testing dataset. This study underscores the potential of ML methods in precisely predicting strut forces in deep excavation engineering, contributing to enhanced safety measures and project planning.

Ulrich Römer, Stefan Hartmann, Jendrik-Alexander Tröger et al.

In the framework of solid mechanics, the task of deriving material parameters from experimental data has recently re-emerged with the progress in full-field measurement capabilities and the renewed advances of machine learning. In this context, new methods such as the virtual fields method and physics-informed neural networks have been developed as alternatives to the already established least-squares and finite element-based approaches. Moreover, model discovery problems are starting to emerge and can also be addressed in a parameter estimation framework. These developments call for a new unified perspective, which is able to cover both traditional parameter estimation methods and novel approaches in which the state variables or the model structure itself are inferred as well. Adopting concepts discussed in the inverse problems community, we distinguish between all-at-once and reduced approaches. With this general framework, we are able to structure a large portion of the literature on parameter estimation in computational mechanics - and we can identify combinations that have not yet been addressed, two of which are proposed in this paper. We also discuss statistical approaches to quantify the uncertainty related to the estimated parameters, and we propose a novel two-step procedure for identification of complex material models based on both frequentist and Bayesian principles. Finally, we illustrate and compare several of the aforementioned methods with mechanical benchmarks based on synthetic and real data.

MSc Eng. Mateusz, Szczęśniewicz, MSc Eng. Karolina et al.

13-15 JUNE 2023 | WROCLAW, POLAND HYBRID EVENT The title of the Conference XXIII Conference of PhD Students and Young Scientists “Interdisciplinary topics in mining, geology and geomatics” The location and the date of the conference hybrid event – online and onsite conference, 13th to 15th June, 2023 in Wroclaw, Poland XXIIIrd Conference of PhD Students and Young Scientists “Interdisciplinary topics in mining, geology and geomatics” continues a series of events that started in 2000 at Wroclaw University of Science and Technology. Scientific programme of the Conference focuses on four thematic panels: 1. Mining Engineering: sustainable development, digitalisation in mining, problems of securing, protecting and using remnants of old mining works, underground mining, open-pit mining, mineral processing, waste management, mining machinery, mine transport, economics in mining, mining aeronautics, ventilation and air conditioning in mines 2. Earth and Space Sciences: geology, hydrogeology, environmental protection, extraterrestrial resources, groundwater and medicinal waters, engineering and environmental protection, geotourism 3. Geoengineering: environmental protection, applied geotechnics, rock and soil mechanics, geohazards 4. Geoinformation: mining geodesy, GIS, photogrammetry and remote sensing, geodata modeling and analysis. The XXIII Conference of PhD Students and Young Scientists was held as a hybrid event, that is as a traditional onsite conference with the possibility in on-line participation in real-time. The XXIII Conference of PhD Students and Young Scientists took place in 13th to 15th June, 2023 in Wroclaw, Poland. Because the conference focused on four thematic panels, four different special opening lectures were delivered by wellknown scientists: - Professor Tim Wright (University of Leeds, England) - Professor Rubén Galindo-Aires (Technical University of Madrid, Spain) - Professor Przemysław B. Kowalczuk (Norwegian University of Science and Technology, Norway) - Dr. Jakub Ciążela (Polish Academy of Sciences, Poland). The Conference was divided into 7 oral sessions (with 29 presentations) and 1 poster session (with 40 posters). The amount of time provided to one presentation was 15 minutes, after presentation there was 5 minutes available for discussion. The poster session was available throughout the event, and the posters were available for online viewing on the Conference’s website with the possibility of make discussion and ask questions in real time via zoom meeting application as well. During this year’s Conference, Organizing Committee has prepared a unique opportunity to participate in onsite workshop. The aim of the workshop was to familiarize participants with the capabilities of ArcGIS Pro software in utilizing Deep Learning tools. They were learning how to create training samples, train models, and use them for their research. List of Scientific Committee, Organizing Committee Editorial Team are available in this Pdf.

M. Hajihassani, D. J. Armaghani, R. Kalatehjari

Meng Wang, Jiawen Zhou, Junlin Chen et al.

Local geometric information and discontinuity features are key aspects of the analysis of the evolution and failure mechanisms of unstable rock blocks in rock tunnels. This study demonstrates the integration of terrestrial laser scanning (TLS) with distinct element method for rock mass characterization and stability analysis in tunnels. TLS records detailed geometric information of the surrounding rock mass by scanning and collecting the positions of millions of rock surface points without contact. By conducting a fuzzy K-means method, a discontinuity automatic identification algorithm was developed, and a method for obtaining the geometric parameters of discontinuities was proposed. This method permits the user to visually identify each discontinuity and acquire its spatial distribution features (e.g. occurrences, spacings, trace lengths) in great detail. Compared with hand mapping in conventional geotechnical surveys, the geometric information of discontinuities obtained by this approach is more accurate and the identification is more efficient. Then, a discrete fracture network with the same statistical characteristics as the actual discontinuities was generated with the distinct element method, and a representative numerical model of the jointed surrounding rock mass was established. By means of numerical simulation, potential unstable rock blocks were assessed, and failure mechanisms were analyzed. This method was applied to detection and assessment of unstable rock blocks in the spillway and sand flushing tunnel of the Hongshiyan hydropower project after a collapse. The results show that the noncontact detection of blocks was more labor-saving with lower safety risks compared with manual surveys, and the stability assessment was more reliable since the numerical model built by this method was more consistent with the distribution characteristics of actual joints. This study can provide a reference for geological survey and unstable rock block hazard mitigation in tunnels subjected to complex geology and active rockfalls.

Nan Rui, Xiao Yejing, Wang Jing

Under the background of risk society, the foreseeable and unforeseeable risk factors significantly increase, which puts forward higher requirements for the modernization of China's emergency management system and capability.Scenario analysis is an analytical method and practical tool to study the uncertain future.Emergency management highly relies on scenario analysis for investigating uncertain factors.Taking the situation analysis of emergency management as the research object, this paper put forward a knowledge graph by CiteSpace to examine the trend and law of the research.Specifically, it probed into the contents and hot spots of micro-deconstruction scenario analysis from theoretical revision and expansion, process adjustment and specification, method application and practice.The research shows that the scenario analysis of emergency management has not formed a clear research paradigm, but it has great potential; the research content is diversified, but the localization research is relatively deficient; Current research can not meet practical needs, and the high complexity of major emergencies invites scenario analysis research.

Riccardo Zabatta, Laura Govoni, Aligi Foglia et al.

The article presents a continuum approach to predict the response of pile foundations for jacket-supported offshore wind turbines. Tensile loading conditions are examined, which may be critical for piles used in combination with this structure type, generally adopted to exploit wind energy in intermediate water depths. The approach is developed to guarantee a simple implementation with a limited number of input data easily attainable from cone penetration tests and laboratory tests, and to ensure computational cost-effectiveness. Data from technical-scale tests on open-ended steel piles driven in dense sand and subjected to drained pull-out are used to assess the performance of the approach. The results are shown to be accurate, approximating rather closely the experimental load–displacement curves. The accuracy of the approach is also compared to that obtained with a recently proposed design method, to investigate the predictive capacity of the approach and its potential to support preliminary design activities.

Rahul Arun, Tim Colonius

We simulate the head-on collision between vortex rings with circulation Reynolds numbers of 4000 using an adaptive, multiresolution solver based on the lattice Green's function. The simulation fidelity is established with integral metrics representing symmetries and discretization errors. Using the velocity gradient tensor and structural features of local streamlines, we characterize the evolution of the flow with a particular focus on its transition and turbulent decay. Transition is excited by the development of the elliptic instability, which grows during the mutual interaction of the rings as they expand radially at the collision plane. The development of antiparallel secondary vortex filaments along the circumference mediates the proliferation of small-scale turbulence. During turbulent decay, the partitioning of the velocity gradients approaches an equilibrium that is dominated by shearing and agrees well with previous results for forced isotropic turbulence. We also introduce new phase spaces for the velocity gradients that reflect the interplay between shearing and rigid rotation and highlight geometric features of local streamlines. In conjunction with our other analyses, these phase spaces suggest that, while the elliptic instability is the predominant mechanism driving the initial transition, its interplay with other mechanisms, e.g. the Crow instability, becomes more important during turbulent decay. Our analysis also suggests that the geometry-based phase space may be promising for identifying the effects of the elliptic instability and other mechanisms using the structure of local streamlines. Moving forward, characterizing the organization of these mechanisms within vortices and universal features of velocity gradients may aid in modelling turbulent flows.

M. Zhelnin, A. Kostina, A. Prokhorov et al.

Artificial freezing of water-bearing soil layers composing a sedimentary deposit can induce frost heave and water migration that affect the natural stress–strain state of the soil layers and freezing process. In the present paper, a thermo-hydro-mechanical (THM) model for freezing of water-saturated soil is proposed to study the effects of frost heave and water migration in frozen soils on the formation of a frozen wall and subsequent excavation activity for sinking a vertical shaft. The governing equations of the model are formulated relative to porosity, temperature, and displacement which are considered as primary variables. The relationship between temperature, pore water, and ice pressure in frozen soil is established by the Clausius–Clapeyron equation, whereas the interaction between the stress–strain behavior and changes in porosity and pore pressure is described with the poromechanics theory. Moreover, constitutive relations for additional mechanical deformation are incorporated to describe volumetric expansion of soil during freezing as well as creep strain of soil in the frozen state. The ability of the proposed model to capture the frost heave of frozen soil is demonstrated by a comparison between numerical results and experimental data given by a one-sided freezing test. Also to validate the model in other freezing conditions, a radial freezing experiment is performed. After the validation procedure, the model is applied to numerical simulation of artificial freezing of silt and sand layers for shaft sinking at Petrikov potash mine in Belarus. Comparison of calculated temperature with thermal monitoring data during active freezing stage is presented. Numerical analysis of deformation of unsupported sidewall of a shaft inside the frozen wall is conducted to account for the change in natural stress–strain state of soil layers induced by artificial freezing.