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

Tong Qiu, Kaibin Ye, Xiangsheng Chen et al.

CHAI Zhaoyun, LI Jian, HE Lixia et al.

Coupled remediation by electrodynamic permeable reaction barrier (EK-PRB) could effectively remove heavy metal ions from contaminated soil in coal mine areas as this technology combines the advantages of both electrokinetic remediation and permeable reaction barrier. Taking Cd-contaminated soil as the research object, this study conducted physical simulation experiment of EK-PRB coupled remediation to investigate the evolution patterns of pH value of electrolyte and soil, Cd2+ removal efficiency, current and total electric energy consumption in coupled remediation. We found that the pH value of the electrolyte and current exhibited cyclic variations during the remediation process: the pH value of anode decreased while that of cathode increased, the current first increased and then decreased within the cycle. After remediation, the pH value and Cd2+ enrichment index of contaminated soil increased successively from anode to cathode. When a mixture of citric acid and NaCl was used as electrolyte, Cd2+ removal efficiency and current increased significantly, demonstrating maximum remediation efficiency. Montmorillonite as PRB active filling material could effectively reduce the OH- concentration and migration rate produced by cathodic electrolysis, showing higher removal efficiency of Cd2+, lower electric energy consumption, and maximum remediation efficiency. The voltage gradient is positively correlated with Cd2+ removal efficiency and electric energy consumption. Given factors such as Cd2+ removal efficiency, electric energy consumption and cost-effectiveness, the remediation efficiency reaches its maximum when the voltage gradient is 2.5 V/cm.

Kang Chen, Rui Zhang, Shengyang Yuan et al.

This paper presents a multi-scale experimental investigation of the weathering degradation of red mudstone. Natural rocks were extracted from the surface ground to 120 m, in which three sets of samples were selected to consider the different initial rock fabrics. The long-term relative humidity (RH) cycles under two amplitudes were imposed on red mudstone to simulate the weathering process. After RH cycles, a series of uniaxial compression tests, Brazilian splitting tests and bender-extender element tests were carried out to examine the reduction in strength and stiffness. The objective of this study is to develop an extended stress-volume framework characterizing the degradation of natural red mudstone both at microscale and macroscale. Accompanied by the irreversible swelling of the rock specimen is the progressive degradation of strength, stiffness and Poisson's ratio. A unified exponential degradation model in terms of the irreversible volumetric strain was thus proposed to capture such a degradation pattern. The effect of the initial rock fabric was evident. The highest degradation rate and potential were identified in slightly weathered specimens. Significant slaking of aggregates and crack propagation were confirmed by scanning electron microscope (SEM) micrographs, which were considered as the main consequence of structure damage leading to degradation of mechanical properties. The structure damage during RH cycles denoted the hysteresis nature in the response to the cycling hydraulic reaction, in turn causing the increase in volumetric strain. Thus, the stress-volume relation rather than the suction relation was found in more reasonable agreement with the experimental results.

GE Jinyu1, 2 , XU Fei1 , HAN Xun1, HAN Xuesong1, QIAN Wenxun1, LI Huaisen1

In this study, a new method based on a chemical thermodynamic model is proposed to quantitatively predict the phase distribution in cemented soil. Commercial kaolinite with simple phase composition is selected, and a series of cemented kaolinite samples are prepared by adjusting cement content, binder-water ratio, and NaOH/KOH doses. The samples are then characterized qualitatively and quantitatively using X-ray diffraction (XRD) and 29Si-nuclear magnetic resonance (29Si-NMR) techniques, respectively. Then, a thermodynamic model of cemented kaolinite is constructed using the GEMS software and the chemical thermodynamic database Cemdata18, simulating the evolution of mineral distribution in cemented kaolinite under different cement contents and alkali activation conditions. The simulation results are compared and analyzed with the micro-characterization results. The research indicates that the thermodynamic model can reliably predict the mineral distribution evolution in cemented kaolinite. Meanwhile, cement and alkalis have varying maginitude of "dissolution-polymerization" effects on the high polymerization chemical groups in soil, and the type of alkali significantly affects the depolymerization of clay minerals and the type and structural characteristics of the polymerization products.

Pierluigi Alesiani, Paolo Ruggeri, Viviene M.E. Fruzzetti et al.

Evaluating the seismic performance of retaining walls is a significant engineering challenge due to non-linear soil-structure interaction, site response effects and ground motion properties. State of the art methods, based on non-linear dynamic analysis, are nowadays able to give reliable results when the numerical modeling is carried out with careful evaluation of seismic signals and appropriate choice of constitutive relationship for soils. However, a similar analysis is mostly restricted to relevant infrastructures. For large part of the practical situations, the simplified seismic analysis still represents the most used tool for design and verification. The new generation of Eurocode in Europe has introduced some innovations on the use of simplified seismic analyses making them more rationale and site-specific. In this paper, a case study involving the seismic evaluation of an existing anchored sheet-pile quay wall in the Ravenna port is presented. A well-known geotechnical setting and the data from an extensive field and laboratory investigation available for the area, allowed to perform both simplified and non-linear dynamic seismic analyses. The simplified seismic analysis according to the pseudo-static method outlined in the new draft of Eurocode 8 (FprEN1998:2024 TC250 – part 1 and 5), has been carried out and compared with the seismic performance of the quay wall evaluated through a 2D FEM non-linear dynamic analysis. Also, the seismic displacements of the quay wall from 2D FEM non-linear dynamic analysis were compared with recently proposed Newmark-type simplified methods. Relevant aspects of the presented case study are the very deep location of the bedrock, which required a separate model for site response analysis and 2D FEM non-linear dynamic analysis of the structures and the significant length of the wall embedment, due to poor geotechnical properties of the ground, which resulted in a pronounced spatial variation with depth of the ground motion.

Vladyslav Bulhakov, Giordano d'Aloisio, Claudio Di Sipio et al.

The introduction of large language models (LLMs) has enhanced automation in software engineering tasks, including in Model Driven Engineering (MDE). However, using general-purpose LLMs for domain modeling has its limitations. One approach is to adopt fine-tuned models, but this requires significant computational resources and can lead to issues like catastrophic forgetting. This paper explores how hyperparameter tuning and prompt engineering can improve the accuracy of the Llama 3.1 model for generating domain models from textual descriptions. We use search-based methods to tune hyperparameters for a specific medical data model, resulting in a notable quality improvement over the baseline LLM. We then test the optimized hyperparameters across ten diverse application domains. While the solutions were not universally applicable, we demonstrate that combining hyperparameter tuning with prompt engineering can enhance results across nearly all examined domain models.

Martin Obaidi, Marc Herrmann, Elisa Schmid et al.

Sentiment analysis is an essential technique for investigating the emotional climate within developer teams, contributing to both team productivity and project success. Existing sentiment analysis tools in software engineering primarily rely on English or non-German gold-standard datasets. To address this gap, our work introduces a German dataset of 5,949 unique developer statements, extracted from the German developer forum Android-Hilfe.de. Each statement was annotated with one of six basic emotions, based on the emotion model by Shaver et al., by four German-speaking computer science students. Evaluation of the annotation process showed high interrater agreement and reliability. These results indicate that the dataset is sufficiently valid and robust to support sentiment analysis in the German-speaking software engineering community. Evaluation with existing German sentiment analysis tools confirms the lack of domain-specific solutions for software engineering. We also discuss approaches to optimize annotation and present further use cases for the dataset.

Paris Avgeriou, Nauman bin Ali, Marcos Kalinowski et al.

Increasingly, courses on Empirical Software Engineering research methods are being offered in higher education institutes across the world, mostly at the M.Sc. and Ph.D. levels. While the need for such courses is evident and in line with modern software engineering curricula, educators designing and implementing such courses have so far been reinventing the wheel; every course is designed from scratch with little to no reuse of ideas or content across the community. Due to the nature of the topic, it is rather difficult to get it right the first time when defining the learning objectives, selecting the material, compiling a reader, and, more importantly, designing relevant and appropriate practical work. This leads to substantial effort (through numerous iterations) and poses risks to the course quality. This chapter attempts to support educators in the first and most crucial step in their course design: creating the syllabus. It does so by consolidating the collective experience of the authors as well as of members of the Empirical Software Engineering community; the latter was mined through two working sessions and an online survey. Specifically, it offers a list of the fundamental building blocks for a syllabus, namely course aims, course topics, and practical assignments. The course topics are also linked to the subsequent chapters of this book, so that readers can dig deeper into those chapters and get support on teaching specific research methods or cross-cutting topics. Finally, we guide educators on how to take these building blocks as a starting point and consider a number of relevant aspects to design a syllabus to meet the needs of their own program, students, and curriculum.

Zizhuo Xiang, Taehyun Moon, Joung Oh et al.

This study aims to investigate the feasibility of deriving in situ horizontal stresses from the breakout width and depth using the analytical method. Twenty-three breakout data with different borehole sizes were collected and three failure criteria were studied. Based on the Kirsch equations, relatively accurate major horizontal stress (σH) estimations from known minor horizontal stress (σh) were achieved with percentage errors ranging from 0.33% to 44.08% using the breakout width. The Mogi-Coulomb failure criterion (average error: 13.1%) outperformed modified Wiebols-Cook (average error: 19.09%) and modified Lade (average error: 18.09%) failure criteria. However, none of the tested constitutive models could yield reasonable σh predictions from known σH using the same approach due to the analytical expression of the redistributed stress and the nature of the constitutive models. In consideration of this issue, the horizontal stress ratio (σH/σh) is suggested as an alternative input, which could estimate both σH and σh with the same level of accuracy. Moreover, the estimation accuracies for both large-scale and laboratory-scale breakouts are comparable, suggesting the applicability of this approach across different breakout sizes. For breakout depth, conformal mapping and complex variable method were used to calculate the stress concentration around the breakout tip, allowing the expression of redistributed stresses using binomials composed of σH and σh. Nevertheless, analysis of the breakout depth stabilisation mechanism indicates that additional parameters are required to utilise normalised breakout depth for stress estimation compared to breakout width. These parameters are challenging to obtain, especially under field conditions, meaning utilising normalised breakout depth analytically in practical applications faces significant challenges and remains infeasible at this stage. Nonetheless, the normalised breakout depth should still be considered a critical input for any empirical and statistical stress estimation method given its significant correlation with horizontal stresses. The outcome of this paper is expected to contribute valuable insights into the breakout stabilisation mechanisms and estimation of in situ stress magnitudes based on borehole breakout geometries.

YANG Guoliang, SHANG Zhuo, ZOU Zehua et al.

This study attempts to investigate the dynamic tensile mechanical properties of sandstone under freeze-thaw cycle by using the split Hopkinson pressure bar (SHPB)test system to perform dynamic splitting tests on sandstone samples with freeze-thaw cycle 0, 10, 20 and 40 times at different impact speeds.Also adopting the high-speed digital image correlation (DIC), we observed the dynamic tensile failure process of the specimen, where we analyzed the strength characteristics, deformation process and failure form of frozen sandstone under dynamic tensile stress in different freeze-thaw cycles.Results show that 1)the dynamic tensile σ-t curves of frozen sandstone and ordinary sandstone exhibit similar patterns of stress variation under different freeze-thaw cycles, which can be divided into four stages: low speed growth section, high speed growth section, peak plateau section and decreasing section; 2)the peak tensile stress increases linearly with the increase of stress loading rate; 3)the peak tensile stress of frozen rock has a certain freeze-thaw cycle effect, and there is a strong correlation between the peak tensile stress and the number of freeze-thaw cycles.The dynamic tensile strength of frozen rock increases first and then decreases as the number of freeze-thaw cycles increases.Under the same impact pressure, the frozen rock specimen shows certain freeze-thaw cycle effect as the tensile strain at the center shows N=40>20>0>10 under 4 kinds of freeze-thaw cycles.

YANG Gaosheng 1, 2, BAI Bing 2, CHEN Wenxuan 1, MAO Haitao 1, LIU Zhonghua 1, LAN Xiaoling 1

The joints of composite blocks of buffer materials as potential weak parts in the engineering barrier system of high-level radioactive waste (HLW) repository must be studied in depth. Therefore, the evolution of temperature and volumetric water content with time at different locations of Gaomiaozi (GMZ) composite bentonite samples before and after simulated water inflow is measured by using the developed experimental devices. According to the experimental results, the thermal conductivity and hydraulic conductivity of the joint location after healing of composite samples are obtained. The experimental results show that the change of the internal temperature of the composite bentonite samples is mainly affected by the temperature boundary, and the change of the internal water has small effects on it. In a short period of time, the loading of hydraulic boundary conditions only makes the volumetric water content of the soil near the hydraulic boundary increase significantly, but has small effects on other locations. Affected by the temperature boundary, the volumetric water content of the soil near the temperature boundary gradually decreases with time. The thermal conductivity and permeability of the joint location after healing can meet the requirements of the engineering barrier of the HLW repository.

Yijie WANG, Chuanming MA, Jing GUO et al.

Objective Carbonate rocks have a significant carbon sink effect in water cycle. Since karst landforms are widely distributed in China, research on the potential of karst carbon sinks plays an important role in formulating regional strategies for increasing carbon sinks. Methods In this study, groundwater monitoring points in Hubei Province, which is located in the karst area of Southwest China, were selected. Quantitative calculations and method comparisons were performed based on the hydrochemical runoff method and the infiltration-equilibrium chemistry method. The spatial pattern and magnitude of karst carbon sinks in the hilly mountains of Hubei Province from 2019 to 2021 were evaluated via ArcGIS spatial analysis techniques. Additionally, the most suitable method for estimating karst carbon sinks at the regional scale were explored, the comprehensive analysis of the drivers of karst carbon sinks was performed, and the potential for increasing sinks were explored. Results The results showed that: (1) the intensity of carbon sinks estimated by the infiltration-equilibrium chemistry method were 2020>2019>2021. The total amount of karst carbon sinks in wet year (2020) was approximately 6 times of that in dry year (2019). The average annual carbon sink intensity in the three years was 12.84 t/(km2·a) and the annual total amount of carbon reached 163.89×104 t/a; (2) the infiltration-equilibrium chemistry method was more accurate in calculation results and simpler in data acquisition than the hydrochemical runoff method, and had a certain universality at both large and small spatial scales; (3) the change in carbon sinks was highly dynamic. The extent of changes in carbon sinks under climate change was mainly determined by runoff depth, with the intensity of carbon sinks increasing with runoff depth, while land use regulated the intensity of carbon sinks in karst processes; and (4) the karstification is strong in southwestern Hubei Province, so a pilot field of karst carbon sinks could be established within the area to quantitatively evaluate artificial interventions to increase carbon sinks. Conclusion This study not only provides an accurate and easy-to-use method for estimating karst carbon sinks, but also determines the magnitude and spatial pattern of karst carbon sinks in Hubei Province and figures out the coupling effect of the driving factors of carbon sink intensity, which demonstrates the complexity and anthropogenic control lability of karst carbon sinks. The results of this study provides a reliable scientific basis for the formulation of environmental protection policies and artificial sink increase measures.

Sonja Hyrynsalmi, Ella Peltonen, Fanny Vainionpää et al.

In the extant literature, there has been discussion on the drivers and motivations of minorities to enter the software industry. For example, universities have invested in more diverse imagery for years to attract a more diverse pool of students. However, in our research, we consider whether we understand why students choose their current major and how they did in the beginning decided to apply to study software engineering. We were also interested in learning if there could be some signs that would help us in marketing to get more women into tech. We approached the topic via an online survey (N = 78) sent to the university students of software engineering in Finland. Our results show that, on average, women apply later to software engineering studies than men, with statistically significant differences between genders. Additionally, we found that marketing actions have different impacts based on gender: personal guidance in live events or platforms is most influential for women, whereas teachers and social media have a more significant impact on men. The results also indicate two main paths into the field: the traditional linear educational pathway and the adult career change pathway, each significantly varying by gender

Mario Mally, Bernard Kapidani, Melina Merkel et al.

The simulation of electromagnetic devices with complex geometries and large-scale discrete systems benefits from advanced computational methods like IsoGeometric Analysis and Domain Decomposition. In this paper, we employ both concepts in an Isogeometric Tearing and Interconnecting method to enable the use of parallel computations for magnetostatic problems. We address the underlying non-uniqueness by using a graph-theoretic approach, the tree-cotree decomposition. The classical tree-cotree gauging is adapted to be feasible for parallelization, which requires that all local subsystems are uniquely solvable. Our contribution consists of an explicit algorithm for constructing compatible trees and combining it with a dual-primal approach to enable parallelization. The correctness of the proposed approach is proved and verified by numerical experiments, showing its accuracy, scalability and optimal convergence.

Jun Tsuzurugi

In this paper, we analyze Gaussian processes using statistical mechanics. Although the input is originally multidimensional, we simplify our model by considering the input as one-dimensional for statistical mechanical analysis. Furthermore, we employ periodic boundary conditions as an additional modeling approach. By using periodic boundary conditions, we can diagonalize the covariance matrix. The diagonalized covariance matrix is then applied to Gaussian processes. This allows for a statistical mechanical analysis of Gaussian processes using the derived diagonalized matrix. We indicate that the analytical solutions obtained in this method closely match the results from simulations.

LIANG Jianwen , LI Dongqiao

Based on the response deformation method, a longitudinal seismic design method for underground cross utility tunnels is proposed. By changing the phase angle of the displacement function, which deforms the site for one period, the periodic ground deformation input is realized. The deformation history of T-type precast utility tunnels is analyzed, as well as the most unfavorable modes for structural deformation and internal forces around the cross node. Through the orthogonal test analysis, the seismic responses of the T-type underground utility tunnels under different site parameters and seismic input parameters are studied, as well as the sensitivity analysis for the most unfavorable modes. The results show that the periodic ground deformation input can catch the most unfavorable modes of structural deformation and internal forces, and the incident angle of seismic wave controls the most unfavorable modes of structural deformation and internal forces. The proposed method can be directly used for the longitudinal seismic design of underground cross structures.

A. N. Khimenkov, V. Gagarin

The object of the study is the processes of metamorphism of frozen rocks, including structural restructuring, as well as plastic and brittle deformations of underground ice. In geocryology, many experts note the importance of considering the processes of deformation of frozen rocks. At the same time, the deformed rocks themselves do not stand out in a separate category, which makes it difficult to study the development of cryogenic geosystems after their formation. The main method used in this article is the analysis of the results of previous studies by various authors on the topic under consideration. The theoretical basis of the proposed approach is the provisions developed within the framework of the mechanics of frozen soils and structural ice science. The synthesis of the analyzed materials was carried out on the basis of a geosystem approach. In the proposed work, for the first time, a comparative analysis of structural deformations of various kinds of cryogenic formations was carried out. The relevance of the topic under consideration is due to the need to study the patterns of deformation of frozen rocks in natural conditions. Theoretically, this is important for a deeper understanding of the processes occurring in the cryolithozone. For practical purposes, work in this direction will allow us to more accurately assess the possibility of the development of dangerous engineering-geological processes with man-made impacts on frozen rocks. Changes in the structure of frozen rocks continue after the formation of the primary structure. Deformations, that is, violations of the primary addition, are an integral part of the structure of frozen rocks. Data on deformations of the primary cryogenic structure provide information about the history of the development of cryogenic geosystems that have already been formed. It is necessary to develop a classification of textural and structural deformations of the cryogenic structure of frozen rocks, in which a special type should be distinguished - metamorphosed ice formations. It is necessary to develop methods of structural and deformation analysis that allow establishing links between the observed deformations of the cryogenic structure and the processes occurring in frozen rocks.

Juciela C. dos Santos, R. Coutinho

Masoud Hatami Alooghareh, Atefeh Kabipour, Mohamadhosein ghazavi et al.

Application of CO2 gas in foam enhanced oil recovery (EOR) processes has emerged as a win-win strategy for achieving higher oil recovery factor and reducing greenhouse gas emission, which can significantly help the protection of the ozone layer from depletion. However, lower stability of CO2-foam, as compared to the N2- and CH4-foams, has tempted us to examine combinations of CO2 with these gases to not only improve the stability of the produced foam but also have CO2 as the gaseous phase of the foam. In this study, we investigated the effect of different gases and the mixture thereof on the performance of foams in EOR while the aqueous phase of foams is a constant mixture of Cocamidopropyl betaine surfactant (0.03 wt%) and silica nanoparticle (0.1 wt%). To this end, seven different gases, including N2, CO2, CH4, 80% N2 + 20% CO2, 80% CH4 + 20% CO2, 50% CH4 + 50% CO2, 50% N2 + 50% CO2 were used as the gases phase for foam generation and the performance of the produced foams were examined through the following experiments: bulk foam stability tests, apparent foam viscosity measurements and core flooding tests. The results of foam stability tests showed that half-life time for the CO2-, CH4- and N2-foams are 13.5, 17.0 and 44.0 min, respectively. Also, as revealed from apparent viscosity measurements, the N2- and 80% N2+20% CO2 foams have higher apparent foam viscosity values followed by 50% N2+50% CO2 foam. Furthermore, we showed that a combination of 80% N2 + 20% CO2 as the gaseous phase for foam generation could not only improve CO2-foam stability, as compared to other foams, but also can substantially increase ultimate oil recovery (56.6 %OOIP), even more than that for N2 foam (48.6 %OOIP), obtained from core flooding experiments.

Hyuntae Lim, YounJoon Jung

We introduce a reaction-path statistical mechanics formalism based on the principle of large deviations to quantify the kinetics of single-molecule enzymatic reaction processes under the Michaelis-Menten mechanism, which exemplifies an out-of-equilibrium process in the living system. Our theoretical approach begins with the principle of equal a priori probabilities and defines the reaction path entropy to construct a new nonequilibrium ensemble as a collection of possible chemical reaction paths. As a result, we evaluate a variety of path-based partition functions and free energies using the formalism of statistical mechanics. They allow us to calculate the timescales of a given enzymatic reaction, even in the absence of an explicit boundary condition that is necessary for the equilibrium ensemble. We also consider the large deviation theory under a closed-boundary condition of the fixed observation time to quantify the enzyme-substrate unbinding rates. The result demonstrates the presence of a phase-separation-like, bimodal behavior in unbinding events at a finite timescale, and the behavior vanishes as its rate function converges to a single phase in the long-time limit.