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

Diana A. Reznikova, Mariia V. Barannikova, Lidia M. Shnakhova et al.

DNA sequencing technologies play a key role in modern soil microbiome research, providing a deep understanding of its structure and functional role in ecosystems. 16S rRNA gene, region of 18S-ITS-28S sequencing and shotgun sequencing using modern sequencing technologies (Illumina, Pacific Biosciences (PacBio), Oxford Nanopore Technologies (ONT)) allow us to identify the diversity and dynamics of microbial communities with high accuracy and resolution, which significantly expands our knowledge of biological processes and interactions between microorganisms in the soil. Soil microbiome analysis using sequencing contributes to the development of innovative methods for sustainable agricultural land management, improved fertility, plant disease management, and increased crop yields. Despite its significant potential, each sequencing technology has its own advantages and limitations related to accuracy, depth of coverage, cost, and data analysis complexity. Understanding these characteristics is crucial for selecting the optimal methods depending on the research objectives and available resources. This review systematizes modern sequencing methods, their technical capabilities and limitations, bioinformatics tools for sequencing data analysis, considers examples of successful applications in the study of soil microbiome in various ecosystems, and emphasizes new trends in metagenomics. In-depth study and development of soil microbiome sequencing technologies contributes to more sustainable and resource-efficient agriculture, emphasizing the need for a comprehensive and informed approach to the analysis of microbial communities.

WANG Ruxia, LI Weiyu, TANG Xi et al.

To promote dynamic disaster prevention and blasting efficiency in deep mining, this study prepared wave-impedance rock materials by adjusting air-entraining agent content. Through nuclear magnetic resonance and uniaxial compression tests, we analyzed the microstructure and static mechanical properties of the specimens, particularly the effects of wave impedance and loading rate on static strength, failure modes, and energy evolution. Results show that higher air-entraining agent content increased porosity but reduced wave impedance and compressive strength. At constant wave impedance, compressive strength increased with higher loading rate, coupled with rising fragmentation degree and shear angle. Conversely, lower wave impedance at fixed loading rates reduced strength, fragmentation, and shear angle. Total energy and elastic strain energy decreased, while dissipated energy decreased in amount but increased in its proportion. Brittleness reduced while ductility increased, exhibiting a shift from brittle to ductile failure. This study provides theoretical and statistical support for safe, efficient deep resource mining dynamics.

Kevin Hermann, Sven Peldszus, Jan-Philipp Steghöfer et al.

Software security is of utmost importance for most software systems. Developers must systematically select, plan, design, implement, and especially, maintain and evolve security features -- functionalities to mitigate attacks or protect personal data such as cryptography or access control -- to ensure the security of their software. Although security features are usually available in libraries, integrating security features requires writing and maintaining additional security-critical code. While there have been studies on the use of such libraries, surprisingly little is known about how developers engineer security features, how they select what security features to implement and which ones may require custom implementation, and the implications for maintenance. As a result, we currently rely on assumptions that are largely based on common sense or individual examples. However, to provide them with effective solutions, researchers need hard empirical data to understand what practitioners need and how they view security -- data that we currently lack. To fill this gap, we contribute an exploratory study with 26 knowledgeable industrial participants. We study how security features of software systems are selected and engineered in practice, what their code-level characteristics are, and what challenges practitioners face. Based on the empirical data gathered, we provide insights into engineering practices and validate four common assumptions.

Taichi Ishimaru, Motoyuki Suzuki, Asahi Komori

Suffusion is the detachment and migration of fine particles through voids connected by the matrices of coarse particles. Although water storage structures are known to be affected by fluctuations in seepage flow, due to fluctuations in the water storage levels brought about by rainfall and agricultural activities, the suffusion behavior when the hydraulic gradient is fluctuated is unclear. In this study, one-dimensional downward water-passing experiments with suffusion were performed using a cylindrical column device, and the changes in the amounts of the discharged water and soil particles, as well as the turbidity of the drainage over time, were examined. The behavior of suffusion was investigated from two viewpoints: the quantitative changes in the amount of discharged drainage and the amount of discharged soil particles due to the progress of suffusion, and the qualitative changes in the particle size composition of the discharged soil particles. A unique feature of this study was the tracing of the changes in the particle size composition of the discharged soil particles from the relationship between the turbidity and the concentration of drainage during suffusion. As a result, it was found that not only the amount of soil particles discharged by suffusion, but also the particle size composition of the discharged soil particles changed under both constant and fluctuated hydraulic gradient conditions.

Shahab Hosseini, Danial Jahed Armaghani, Xuzhen He et al.

AbstractThe rockburst phenomenon in excavation endeavours reveals a multitude of complexities and obstacles that significantly impact both the technical and financial dimensions of project execution. Investigating critical rockburst factors in underground excavations is of considerable importance for addressing pivotal safety issues and operational complexities within the field of underground excavation projects. This research proposes an innovative approach based on an expert-based fuzzy cognitive map (FCM) framework, aiming to identify and prioritize the key critical rockburst factors prevalent in underground excavations and tunnelling. A tailored cognitive map of the parameters of problem was constructed, integrating 56 critical and critical factors meticulously curated by a team of seasoned managers, engineers, deputy managers, trainee engineers and assistant managers. The structured cognitive map was meticulously developed, considering the relative weights of the identified critical factors and their intricate interrelationships—all informed by the invaluable insights and expertise of seasoned engineers in the field. Subsequently, the cognitive map underwent a systematic solution process, whereby the causal relationships and influences amongst the identified critical factors were analysed and factored in. The outcomes of the comprehensive analysis unveiled several critical factors: lack of rockburst risk assessments, high in situ stress, presence of rock seams and weak layers, rock quality variations, and geological heterogeneity as the most paramount concerns demanding immediate attention and strategic intervention. By adopting the proposed FCM approach and leveraging the collective expertise of industry professionals, this research offers a robust and systematic framework for comprehensively assessing and addressing the key challenges associated with rockburst events in underground excavations and tunnelling projects, thereby fostering enhanced project performance and efficacy within the field.

Nadia Alshahwan, Mark Harman, Inna Harper et al.

In this paper we address the following question: How can we use Large Language Models (LLMs) to improve code independently of a human, while ensuring that the improved code - does not regress the properties of the original code? - improves the original in a verifiable and measurable way? To address this question, we advocate Assured LLM-Based Software Engineering; a generate-and-test approach, inspired by Genetic Improvement. Assured LLMSE applies a series of semantic filters that discard code that fails to meet these twin guarantees. This overcomes the potential problem of LLM's propensity to hallucinate. It allows us to generate code using LLMs, independently of any human. The human plays the role only of final code reviewer, as they would do with code generated by other human engineers. This paper is an outline of the content of the keynote by Mark Harman at the International Workshop on Interpretability, Robustness, and Benchmarking in Neural Software Engineering, Monday 15th April 2024, Lisbon, Portugal.

Marvin Wyrich, Justus Bogner

LinkedIn is the largest professional network in the world. As such, it can serve to build bridges between practitioners, whose daily work is software engineering (SE), and researchers, who work to advance the field of software engineering. We know that such a metaphorical bridge exists: SE research findings are sometimes shared on LinkedIn and commented on by software practitioners. Yet, we do not know what state the bridge is in. Therefore, we quantitatively and qualitatively investigate how SE practitioners and researchers approach each other via public LinkedIn discussions and what both sides can contribute to effective science communication. We found that a considerable proportion of LinkedIn posts on SE research are written by people who are not the paper authors (39%). Further, 71% of all comments in our dataset are from people in the industry, but only every second post receives at least one comment at all. Based on our findings, we formulate concrete advice for researchers and practitioners to make sharing new research findings on LinkedIn more fruitful.

HOU Shiwei 1, HOU Jinzhao 1, DU Xiuli 2, MENG Suyun 1, QU Jinhong 3

The fragmentation and naturalness of soils make their deformation and strength characteristics have obvious scale effects. Therefore, in order to study the strain localization process of the soils, the distribution and proportional relationship of graded particles cannot be ignored, and the macroscopic mechanical properties must be characterized from multiple scales. Based on the theory of cell model, the soils are regarded as a granular material composed of reinforced particles and matrix. The intrinsic scale law of the samples with different reinforced particle sizes is studied through the triaxial compression tests, and the formation process and initiation mechanism of shear band at meso level are studied through the numerical simulation. The average strain energy release coefficient is introduced to quantitatively verify the strain energy conversion of the soils after reaching the peak stress, and the multi-band initiation and progressive competition process are reproduced. The results show that the strength tests of reinforced particles with different size scales indicate that the discontinuity of particles makes the soils have size effects, and the ratio of intrinsic scale to particle size decreases with the increase of the reinforced particle size. Before the stress peak, the non-elastic dissipative energy increases, leading to strain localization. After the peak, the strain rapidly increases within the shear band, while there is a rebound outside the band.

Qi Wang, Yuncai Wang, Bei Jiang et al.

The rock mass consists of rock blocks and structural planes, which can reduce its integrity and strength. Therefore, accurately obtaining the characteristics of the rock mass structural plane is a prerequisite for evaluating stability and designing supports in underground engineering. Currently, there are no effective testing methods for the characteristic parameters of the rock mass structural plane in underground engineering. The paper presents the digital drilling technology as a new testing method of rock mass structural planes. Flawed rock specimens with cracks of varying widths and angles were used to simulate the rock mass structural planes, and the multifunctional rock mass digital drilling test system was employed to carry out the digital drilling tests. The analysis focuses on the variation laws of drilling parameters, such as drilling pressure and drilling torque, affected by the characteristics of prefabricated cracks, and clarifies the degradation mechanism of rock equivalent compressive strength. Additionally, an identification model for the characteristic parameters of rock mass structural planes during drilling is established. The test results indicate that the average difference of the characteristics of prefabricated cracks identified by the equivalent compressive strength is 2.45° and 0.82 mm, respectively. The identification model while drilling is verified to be correct due to the high identification accuracy. Based on this, a method for testing the characteristic parameters of the surrounding rock structural plane while drilling is proposed. The research offers a theoretical and methodological foundation for precise in situ identification of structural planes of the surrounding rock in underground engineering.

Cui Lin, D.H. Steve Zou

Travis Leadbetter, Prashant K. Purohit, Celia Reina

Far-from-equilibrium phenomena are critical to all natural and engineered systems, and essential to biological processes responsible for life. For over a century and a half, since Carnot, Clausius, Maxwell, Boltzmann, and Gibbs, among many others, laid the foundation for our understanding of equilibrium processes, scientists and engineers have dreamed of an analogous treatment of non-equilibrium systems. But despite tremendous efforts, a universal theory of non-equilibrium behavior akin to equilibrium statistical mechanics and thermodynamics has evaded description. Several methodologies have proved their ability to accurately describe complex non-equilibrium systems at the macroscopic scale, but their accuracy and predictive capacity is predicated on either phenomenological kinetic equations fit to microscopic data, or on running concurrent simulations at the particle level. Instead, we provide a framework for deriving stand-alone macroscopic thermodynamics models directly from microscopic physics without fitting in overdamped Langevin systems. The only necessary ingredient is a functional form for a parameterized, approximate density of states, in analogy to the assumption of a uniform density of states in the equilibrium microcanonical ensemble. We highlight this framework's effectiveness by deriving analytical approximations for evolving mechanical and thermodynamic quantities in a model of coiled-coil proteins and double stranded DNA, thus producing, to the authors' knowledge, the first derivation of the governing equations for a phase propagating system under general loading conditions without appeal to phenomenology. The generality of our treatment allows for application to any system described by Langevin dynamics with arbitrary interaction energies and external driving, including colloidal macromolecules, hydrogels, and biopolymers.

Marcel Grote, Justus Bogner

Today, many systems use artificial intelligence (AI) to solve complex problems. While this often increases system effectiveness, developing a production-ready AI-based system is a difficult task. Thus, solid AI engineering practices are required to ensure the quality of the resulting system and to improve the development process. While several practices have already been proposed for the development of AI-based systems, detailed practical experiences of applying these practices are rare. In this paper, we aim to address this gap by collecting such experiences during a case study, namely the development of an autonomous stock trading system that uses machine learning functionality to invest in stocks. We selected 10 AI engineering practices from the literature and systematically applied them during development, with the goal to collect evidence about their applicability and effectiveness. Using structured field notes, we documented our experiences. Furthermore, we also used field notes to document challenges that occurred during the development, and the solutions we applied to overcome them. Afterwards, we analyzed the collected field notes, and evaluated how each practice improved the development. Lastly, we compared our evidence with existing literature. Most applied practices improved our system, albeit to varying extent, and we were able to overcome all major challenges. The qualitative results provide detailed accounts about 10 AI engineering practices, as well as challenges and solutions associated with such a project. Our experiences therefore enrich the emerging body of evidence in this field, which may be especially helpful for practitioner teams new to AI engineering.

Hengxing Wang, Xiaohao Sun, Linchang Miao et al.

Enzyme-induced carbonate precipitation (EICP) is an emerging technique to improve the soil and most studies are carried out at room temperature. However, considering some foundations are in high-temperature environments (>40 °C), the higher urease activity at high temperature results in the solidification inhomogeneity, limiting the application of EICP. The higher urease activity at high temperature hampers the application of EICP because of solidification inhomogeneity. The garlic extract has been used as a type of urease inhibitor in medical science and food engineering. Here, we propose to use it to control urease activity for sand solidification at high temperature. The effects of garlic extract addition on urease activity and precipitation rates for calcium carbonate (CaCO3) were studied. Extra tests were conducted to study the effect of garlic extract addition on the solidification homogeneity. The results showed that the garlic extract addition significantly decreased urease activity. To reduce the rate of CaCO3 precipitation at different temperatures, a suitable concentration of garlic extract was necessary to obtain a suitable urease activity. In the sand solidification test, garlic extract addition resulted in a smaller difference in sonic time values or CaCO3 contents at different parts of samples. The improved solidification homogeneity can achieve higher strength. The correlation between sonic time values and CaCO3 content was higher than that between CaCO3 content and strength. Appropriate concentrations of garlic extract were obtained at 35 °C, 40 °C, 45 °C, 50 °C, and 55 °C. The proposed garlic extract addition method was significant to improve the homogeneity of solidified soil in practical engineering applications.

Tao Zhang, Liyuan Yu, Yuxuan Peng et al.

The mechanical characteristics of crystalline rocks are affected by the heterogeneity of the spatial distribution of minerals. In this paper, a novel three-dimensional (3D) grain-based model (GBM) based on particle flow code (PFC), i.e. PFC3D-GBM, is proposed. This model can accomplish the grouping of mineral grains at the 3D scale and then filling them. Then, the effect of the position distribution, geometric size, and volume composite of mineral grains on the cracking behaviour and macroscopic properties of granite are examined by conducting Brazilian splitting tests. The numerical results show that when an external load is applied to a sample, force chains will form around each contact, and the orientation distribution of the force chains is uniform, which is independent of the external load level. Furthermore, the number of high-strength force chains is proportional to the external load level, and the main orientation distribution is consistent with the external loading direction. The main orientation of the cracks is vertical to that of the high-strength force chains. The geometric size of the mineral grains controls the mechanical behaviours. As the average grain size increases, the number of transgranular contacts with higher bonding strength in the region connecting both loading points increases. The number of high-strength force chains increases, leading to an increase in the stress concentration value required for the macroscopic failure of the sample. Due to the highest bonding strength, the generation of transgranular cracks in quartz requires a higher concentrated stress value. With increasing volume composition of quartz, the number of transgranular cracks in quartz distributed in the region connecting both loading points increases, which requires many high-strength force chains. The load level rises, leading to an increase in the tensile strength of the numerical sample.

Houzhen Wei, Hao Liu, Xiaoxiao Li et al.

Calcareous sand is widely observed in the foundation of off-shore infrastructure. Although a lot of research has been carried out on the mechanical properties of calcareous sand, study into the influence of the stress–strain path on the mechanical behaviour of calcareous sand is very limited. In this study, a series of triaxial tests were performed on calcareous sand under three different stress paths. The particle morphology of calcareous sand before and after the tests, the stress–strain relationship under different stress paths, and the characteristics of shear strength and deformation were investigated. The results show that the consolidation pressure and stress path have significant effects on the volume strain, strength, and particle breakage of calcareous sand. In addition, the underlying mechanisms of the different behaviours of calcareous sand observed in this study were discussed.

A. Morgun, I. Met, A. Kozub

Taking into account the presence of weak soils on the territory of Ukraine, additional vertical deformations occur in soil foundations, associated with a violation of their structure. Water saturation of such soils leads to a change in VAT and affects the conditions for the reliable operation of construction objects. In this regard, it becomes necessary to strengthen the foundations of these building objects, to improve the bearing capacity of these foundations. Therefore, in practice, the search for new ways to strengthen the foundations, improve their bearing capacity is constantly being carried out. In difficult engineering and geological conditions, the deterioration of the physical and mechanical properties leads to a rise in deformations and a decrease in the bearing capacity of the foundations. Reinforcement of foundations is also necessary when constructing superstructures. In the robot, using the numerical method of boundary elements, the behavior under load of a shallow foundation on a natural basis reinforced with cross piles is predicted. Reinforcement of foundation structures requires determination of their bearing capacity and stress-strain state (SSS) after reconstruction. Normative design of foundations, based on subsidence and rolls, which are borderline permissible from the point of view of the operational suitability and reliability of structures, puts forward increased requirements for the accuracy of calculating the displacements of foundations. The complexity of the properties of soils and the many factors that influence their mechanical behavior have long been a barrier before which the mathematical methods of continuum mechanics were de-strengthened. The emergence of modern ECM allowed algebraicizing the mathematical formulation of most problems in soil mechanics, which require taking into account a large number of nonlinear determining factors and the transition to elastic-plastic models. The use of a numerical eexperiment, as never before, closely linked the physical meaning of the problem, its mathematical formulation, numerical methods of calculation and the ECM. In the robot, to obtain a forecast of the bearing capacity of a reinforced foundation, an elastic-plastic model of a discrete soil medium and a numerical MGE are used.

ZHAN Zheng-gang , ZHANG He-zuo , CHENG Rui-lin , QIU Huan-feng

The deformation of high concrete-faced rockfill dam (CFRD) has a particularly important influence on the safe opercation of impermeable face. To deal with the crushing damage of the impermeable face and the large leakage of dam body, which occurr in many constructed high CFRDs at home and abroad, the reservoirs have to lower the water level for maintenance, which has resulted in large economic losses and even safety hazards for long-term dam operation. Through analyzing the example of a high CFRD with crushing damage, it is found that the lack of systematic deformation control is the main factor for the crushing damage of the face. To prevent the damage of the impermeable face, a systematic method is proposed: "controlling the total deformation of the dam body, transforming harmful deformation, and adapting to vertical deformation". The method has achieved good results in Dongqing CFRD project, which uses mixed hard and soft rocks as dam materials. The project has been operating for more than ten years, and no signs of crushing damage have been detected in the impermeable face. The proposed method provides important reference experience for the design and construction of CFRDs of more than 200 m or even 300 m in height.

Kok-Kwang Phoon, Zi-Jun Cao, Jian Ji et al.

Modeling only constitutes one aspect of decision making. The prevailing limitation of applying modeling to practice is the absence of explicit consideration of uncertainties. This review paper covers uncertainty quantification (soil properties, stratification, and model performance) and uncertainty calculation with a focus on how it enhances the role of modeling in decision making (reliability analysis, reliability-based design, and inverse analysis). The key output from a reliability analysis is the probability of failure, where “failure” is defined as any condition that does not meet a performance criterion or a set of criteria. In contrast to the global factor of safety, the probability of failure respects both mechanics and statistics, is sensitive to data (thus opening one potential pathway to digital transformation), and it is meaningful for both system and component failures. Resilience engineering requires system level analysis. As such, geotechnical software can provide better decision support by computing the probability of failure/reliability index as one basic output in addition to stresses, strains, forces, and displacements. It is further shown that more critical non-classical failure mechanisms can emerge from spatially variable soils that can escape notice if the engineer were to restrict analysis to conventional homogeneous or layered soil profiles.

Xiaojing Li, Yaoyao Zhang, Xueming Sun

Xiang-rong Fu, Y. Ban, Q. Xie et al.