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

LIN Zhaorui1 , JIANG Yalong1, 2, XU Changjie1, 2 , FANG Tao1, 2, FAN Xiaozhen3, DING Haibin1, SHI Yufeng1, 2

In the case of an internally supported pit adjacent to structures, an area of limited soil will be formed outside the pit, which will result in an asymmetric soil condition on both sides of the pit. Indoor model tests are used to analyse the main deformation and bearing capacity of the unilateral asymmetric pit with finite soils, and to investigate the mechanism of the overall push-back displacement of the supporting structure triggered by the asymmetric working condition. The test shows that the deformation of the asymmetric pit consists of two parts: that caused by excavation and that caused by the overall push-back displacement of the supporting structure. The overall pushback displacement of the support structure caused by asymmetry on both sides will lead to the increase of deformation on the semi-infinite side of the soil body, the decrease of soil pressure in the active zone, and the constraint of deformation of the support piles on the finite side. In the case of a large degree of asymmetry between the two sides of the pit, the excessive pushback displacement will cause the deformation of the finite side of the soil body towards the outside of the pit, and the deformation of the supporting piles will change significantly. In the case of a large degree of asymmetry, the soil pressure in the active zone of the finite side appears to change in shape and magnitude, and in the case of a smaller degree of asymmetry, only a change in magnitude occurs. Therefore, when the asymmetric condition of unilateral finite soil body occurs in the foundation pit, the influence of pushback displacement should be fully considered, so as to obtain a more reasonable design and construction scheme of foundation pit support.

Wan-Jun Lei, Yi-Feng Chen, Wang Ren et al.

Drains play an important role in seepage control in geotechnical engineering. The enormous number and one-dimensional (1D) geometry of drainage holes make their nature difficult to be accurately modeled in groundwater flow simulation. It has been well understood that drains function by presenting discharge boundaries, which can be characterized by water head, no-flux, unilateral or mixed water head-unilateral boundary condition. It has been found after years of practices that the flow simulation may become erroneous if the transitions among the drain boundary conditions are not properly considered. For this, a rigorous algorithm is proposed in this study to detect the onset of transitions among the water head, no-flux and mixed water head-unilateral boundary conditions for downwards-drilled drainage holes, which theoretically completes the description of drain boundary conditions. After verification against a numerical example, the proposed algorithm is applied to numerical modeling of groundwater flow through a gravity dam foundation. The simulation shows that for hundreds of downwards-drilled drainage holes used to be prescribed with water head boundary condition, 56% and 2% of them are transitioned to mixed water head-unilateral and no-flux boundary conditions, respectively. The phreatic surface around the drains will be overestimated by 25–33 m without the use of the mixed boundary condition. For the first time, this study underscores the importance of the mixed water head-unilateral boundary condition and the proposed transition algorithm in drain modeling, which may become more essential for simulation of transient flow because of groundwater dynamics.

Giulia Guida, Arianna Pucci, Eliano Romani et al.

This paper describes a field trial of artificial ground freezing (AGF) carried out in connection with the construction of Line C of Roma underground. AGF was one of the options considered for the temporary stabilisation of the ground during the excavation of Colosseo-Fori Imperiali Station. The field trial aimed at assessing the feasibility of AGF in the complex soil profile and groundwater regime of the subsoil of the historical centre of Roma by establishing the response of the subsoil to the imposed freezing loads, the ability to create a continuous frozen wall, and the associated coolant consumption. The extensive monitoring data were exploited to conduct a detailed analysis of the transient freezing process in the stratified subsoil and used to develop and validate a three-dimensional thermo-hydraulic numerical model. Special attention was given to defining and applying appropriate boundary conditions at the freezing pipes. The paper discusses the main factors affecting the time-dependent freezing process and explores the applicability of simplified two-dimensional models for the Fori Imperiali AGF field trial.

ZHANG Jinxun 1, LI Bo 1, JIANG Yusheng 2, ZHOU Liugang 1, YIN Minglun 1, SUN Zhengyang 1, JIANG Hua 2

To solve the problem of uneven wear of the whole shield cutters in the EPB shield tunneling process in sand–pebble strata, a method is established for calculating wear of cutters the based on the principle of friction and wear, and the a theories of uniform wear of shield cutters and the design method of cutterhead and cutters are proposed. The EDEM particle flow numerical software is used to establish a uniform wear shield tunneling model for the sand–pebble stratum 6.6 m in depth, and the uniform wear performance of the whole cutters is verified. The results show that: (1) The uniform wear of the whole cutters can be achieved by designing different cutterhead alignments and arranging a specific number of cutters on each trajectory radius. (2) The cutterhead alignment and the number of cutters are related to the "circumferential knife index β" and "formation lithology index n". In a specific stratum, the value of β is the key factor affecting the design of the shield cutterhead and cutters with uniform wear, and the reasonable range of value of β is 1.83~2 for the conventional shield (2.5 m≤R < 6 m). For large shield (R≥6 m), a flat cutterhead should be designed, and r2 cutters should be arranged on each trajectory. (3) Under the uniform wear scheme, the difference in the wear degree of the whole cutters is small, the tool wear coefficient of the outer ring of the cutterhead is greatly reduced, and the maximum continuous excavation distance without changing the cutters significantly increases.

Zhenpeng Chen, Chong Wang, Weisong Sun et al.

Large Language Models (LLMs) are increasingly integrated into software applications, giving rise to a broad class of prompt-enabled systems, in which prompts serve as the primary 'programming' interface for guiding system behavior. Building on this trend, a new software paradigm, promptware, has emerged, which treats natural language prompts as first-class software artifacts for interacting with LLMs. Unlike traditional software, which relies on formal programming languages and deterministic runtime environments, promptware is based on ambiguous, unstructured, and context-dependent natural language and operates on LLMs as runtime environments, which are probabilistic and non-deterministic. These fundamental differences introduce unique challenges in prompt development. In practice, prompt development remains largely ad hoc and relies heavily on time-consuming trial-and-error, a challenge we term the promptware crisis. To address this, we propose promptware engineering, a new methodology that adapts established Software Engineering (SE) principles to prompt development. Drawing on decades of success in traditional SE, we envision a systematic framework encompassing prompt requirements engineering, design, implementation, testing, debugging, evolution, deployment, and monitoring. Our framework re-contextualizes emerging prompt-related challenges within the SE lifecycle, providing principled guidance beyond ad-hoc practices. Without the SE discipline, prompt development is likely to remain mired in trial-and-error. This paper outlines a comprehensive roadmap for promptware engineering, identifying key research directions and offering actionable insights to advance the development of prompt-enabled systems.

Krishna Ronanki, Simon Arvidsson, Johan Axell

The rapid emergence of generative AI models like Large Language Models (LLMs) has demonstrated its utility across various activities, including within Requirements Engineering (RE). Ensuring the quality and accuracy of LLM-generated output is critical, with prompt engineering serving as a key technique to guide model responses. However, existing literature provides limited guidance on how prompt engineering can be leveraged, specifically for RE activities. The objective of this study is to explore the applicability of existing prompt engineering guidelines for the effective usage of LLMs within RE. To achieve this goal, we began by conducting a systematic review of primary literature to compile a non-exhaustive list of prompt engineering guidelines. Then, we conducted interviews with RE experts to present the extracted guidelines and gain insights on the advantages and limitations of their application within RE. Our literature review indicates a shortage of prompt engineering guidelines for domain-specific activities, specifically for RE. Our proposed mapping contributes to addressing this shortage. We conclude our study by identifying an important future line of research within this field.

Mugeng Liu, Siqi Zhong, Weichen Bi et al.

Large language model-specific inference engines (in short as \emph{LLM inference engines}) have become a fundamental component of modern AI infrastructure, enabling the deployment of LLM-powered applications (LLM apps) across cloud and local devices. Despite their critical role, LLM inference engines are prone to bugs due to the immense resource demands of LLMs and the complexities of cross-platform compatibility. However, a systematic understanding of these bugs remains lacking. To bridge this gap, we present the first empirical study on bugs in LLM inference engines. We mine official repositories of 5 widely adopted LLM inference engines, constructing a comprehensive dataset of 929 real-world bugs. Through a rigorous open coding process, we analyze these bugs to uncover their symptoms, root causes, commonality, fix effort, fix strategies, and temporal evolution. Our findings reveal six bug symptom types and a taxonomy of 28 root causes, shedding light on the key challenges in bug detection and location within LLM inference engines. Based on these insights, we propose a series of actionable implications for researchers, inference engine vendors, and LLM app developers, along with general guidelines for developing LLM inference engines.

Vasyl Mitinsky, Tatiana Sushytska, Y. Vynnykov et al.

Positive experience of arranging high-rise buildings with underground parking lots in soil conditions that have a layer of limestone in the zone of their interaction with pile foundations is presented. It was found that the engineering and geological conditions of Odesa should be classified as complex, in particular due to the presence of weak loess soils in the upper part of the section, and limestone layers in its lower part. In the middle part of the section there is a layer consisting of heavy loams and clays. More compressible sandy loams and meiotic clays serve as the base of the limestones. The insignificant thickness of the middle layer makes it necessary to transfer the load from the buildings with piles to the limestone. With their insignificant thickness, the presence of cracks and outcrops, it becomes possible to develop an excessive tilt of the building as a result of uneven (one-sided) pressing of limestone, which has the nature of a cemented rock. It has been proven that to create a reliable pile foundation, it is important not only to hydraulically tamponade the excavations, but also to consolidate the massif in the area of ​​their location by high-pressure injection of soil-cement solution using cuff columns, as well as to correctly assess the mechanical characteristics of limestone and, first of all, its strength parameters. The conditions for the construction of buildings with a high number of floors on prismatic piles are substantiated. The results of monitoring their subsidence during construction and operation are presented. The experience of 3D modeling by the method of finite elements (FEM) of joint work of the pile-slab foundation of buildings with a base containing layers of limestone and layers of more compressible clay soils in the zone of underground workings is presented.

Adams Ayomide Adeniyi, Alabi Vincent Oluwatobi

This study investigates the causes of recurring road failures at Ekiti State University, Ado-Ekiti, Nigeria, using geophysical methods. The research aims to identify subsurface conditions contributing to these failures, assess the geological and geotechnical properties of the soil and rock, and recommend sustainable construction practices. Electrical resistivity using dipole-dipole configuration and two-dimensional (2D) electrical imaging where used. Data were collected through Ohmega Resistivity Meter, electrodes, and connecting cables, with measurements processed using Dipro-Win software. The results revealed four geological formations: topsoil with resistivity values ranging from 22 – 128 Ωm, a weathered layer (128 – 737 Ωm), a partly weathered basement (737 – 4232 Ωm), and fresh basement rock (>4232 Ωm). Weak zones with low resistivity, suspected as clayey material, were found between stations 3 and 7, with a thickness of less than 2.5 meters. These zones are associated with road cracks and failures. Moderate resistivity zones (likely laterite) between 7 and 10 meters demonstrated field competence. Below these layers, partly weathered and fractured zones were identified above fresh basement rock, with signs of weathering toward the east of the study area. According to the findings, the electrical resistivity approach was a useful tool for identifying the reasons behind road failures along Ekiti State University’s Management Science Road to college of medicine. For road rehabilitation projects, the discovered subsurface anomalies such as inadequately compacted soil and underground water channels offer important insights. The study shows how geophysical techniques can be used to solve problems with road infrastructure and shows how they can be used more widely in road engineering and maintenance projects.

Cheng-yu Miao, M. Jiang, Lei Wang et al.

LI Jing, LI Zequan, SHI Futai et al.

Given the unstructured nature of text data related to hidden dangers in coal mine accidents, extracting latent knowledge is crucial for constructing a knowledge graph of hidden dangers in coal mine accidents. This study proposes annotation types for knowledge entities to describe hidden dangers in coal mine accidents by analyzing the characteristics and latent information in the texts of hidden dangers based on their propagation patterns. Using the Brat annotation tool, we annotated the text data related to hidden dangers of coal mine accidents to construct a dataset for knowledge extraction model. We proposes a BERT-IDCNN-CRF model based on dynamic fusion and introduced a probabilistic fusion algorithm based on Newton's law of cooling. The results indicate that with the incorporation of the probabilistic fusion algorithm, the dynamically weighted BERT-IDCNN-CRF model achieved the best performance in the task of knowledge entity extraction from hidden danger texts. Its precision, recallrate, and F1-score improved by 8.93%, 5.28%, and 7.51%, respectively, significantly enhancing the model's prediction accuracy and stability, while demonstrating excellent adaptability.

Yao Shan, Jun Luo, Binglong Wang et al.

Jet grouting piles were widely employed for ground reinforcement in building and infrastructure engineering due to the low cost and construction convenience. However, this foundation treatment method is not allowed to be used in high-speed railway involved constructions in China because of the concerning of the negative effect on the lateral displacement of the existing high-speed railway. To find a reasonable application distance of jet grouting piles away from existing high-speed railway bridge in deep soft soils with medium sensibility, a series of laboratory and in-situ tests on the influence of the jet grouting piling on the deformation of surrounding soils and adjacent high-speed railway bridge are carried out. The geological characteristics of the construction site and the mechanical properties of the soft soil are deeply investigated by utilizing field and laboratory tests. The piling induced lateral displacement of the surrounding soils is monitored as well as the displacement of an adjacent high-speed railway bridge. The monitoring data reveal that the influence area of the jet grouting piling is approximately 1.75 ∼ 1.85 times of the pile length in deep soft soils. The critical distance of the jet grouting piles from the existing high-speed bridge should be larger than 2 times of the pile length.

Jie Tian, Jixin Hou, Zihao Wu et al.

This study is a pioneering endeavor to investigate the capabilities of Large Language Models (LLMs) in addressing conceptual questions within the domain of mechanical engineering with a focus on mechanics. Our examination involves a manually crafted exam encompassing 126 multiple-choice questions, spanning various aspects of mechanics courses, including Fluid Mechanics, Mechanical Vibration, Engineering Statics and Dynamics, Mechanics of Materials, Theory of Elasticity, and Continuum Mechanics. Three LLMs, including ChatGPT (GPT-3.5), ChatGPT (GPT-4), and Claude (Claude-2.1), were subjected to evaluation against engineering faculties and students with or without mechanical engineering background. The findings reveal GPT-4's superior performance over the other two LLMs and human cohorts in answering questions across various mechanics topics, except for Continuum Mechanics. This signals the potential future improvements for GPT models in handling symbolic calculations and tensor analyses. The performances of LLMs were all significantly improved with explanations prompted prior to direct responses, underscoring the crucial role of prompt engineering. Interestingly, GPT-3.5 demonstrates improved performance with prompts covering a broader domain, while GPT-4 excels with prompts focusing on specific subjects. Finally, GPT-4 exhibits notable advancements in mitigating input bias, as evidenced by guessing preferences for humans. This study unveils the substantial potential of LLMs as highly knowledgeable assistants in both mechanical pedagogy and scientific research.

XUE Song 1, 2, 3, YANG Zhibing 2, 3, CHEN Yifeng 2, 3, TONG Fuguo 1

An in-depth understanding of liquid flows through fracture intersections is important for predicting the seepage characteristics of fracture networks. The flow behavior of liquid at unsaturated intersections is closely related to the flow mode and geometric characteristics of fractures. A modeling study is given on the physical process of droplet splitting through unsaturated fracture intersections, which usually occurs under low flow rate and low saturation conditions. The effects of fracture apertures on droplet splitting behaviors are systematically investigated by varying the main channel width w1 and the branch width w2 of the fracture intersection. It is found that there are two droplet splitting patterns related to the droplet length: the flows dominated by the main channel and those dominated by the branch, which can be distinguished by the critical droplet length. This critical length is controlled by capillary force and permeability of channels, both varying with the channel widths. When the two controlling factors have opposite effects on the droplet splitting, the critical droplet length changes non-monotonously with w2. Conversely, the critical droplet length changes monotonously with w1. In addition, there is an optimal range for the width ratio w2/w1 to maximize the critical droplet length. This study provides theoretical support for predicting the seepage structure of fractured rocks under the conditions of low flow and low saturation.

Long Zhou, Yi Shen, Linxing Guan et al.

Full-scale loading tests were performed on shield segmental linings bearing a high earth pressure and high inner water pressure, focusing on the effects of the inner water load and assembly manner on the mechanical properties of the segmental linings. The test results indicate that the deep-buried segmental linings without inner pressure have a high safety reserve. After the action of high inner water pressure, the lining deformation will increase with the reduction of the safety reserve, caused by the significant decrease in the axial force in the linings. Because the bending moment at the segmental joints is transferred to the segment sections in the adjacent ling rings, the convergence deformation, openings of segmental joints, and bolt strains are smaller for the stagger-jointed lining than those for the continuous-jointed lining; however, dislocations appear in the circumferential joints owing to the stagger-jointed assembly. Although it significantly improves the mechanical performance of the segmental lining, stagger-jointed assembly results in compromising the waterproofing safety of circumferential joints. The stagger-jointed assembly manner can be considered to improve the service performance of shield tunnels bearing high inner water pressure on the premise that circumferential joint waterproofing is satisfied.

Limeng Wang, Xuemeng Liu, Yang Li et al.

In the operation of the integrated energy system (IES), considering further reducing carbon emissions, improving its energy utilization rate, and optimizing and improving the overall operation of IES, an optimal dispatching strategy of integrated energy system considering demand response under the stepped carbon trading mechanism is proposed. Firstly, from the perspective of demand response (DR), considering the synergistic complementarity and flexible conversion ability of multiple energy sources, the lateral time-shifting and vertical complementary alternative strategies of electricity-gas-heat are introduced and the DR model is constructed. Secondly, from the perspective of life cycle assessment, the initial quota model of carbon emission allowances is elaborated and revised. Then introduce a tiered carbon trading mechanism, which has a certain degree of constraint on the carbon emissions of IES. Finally, the sum of energy purchase cost, carbon emission transaction cost, equipment maintenance cost and demand response cost is minimized, and a low-carbon optimal scheduling model is constructed under the consideration of safety constraints. This model transforms the original problem into a mixed integer linear problem using Matlab software, and optimizes the model using the CPLEX solver. The example results show that considering the carbon trading cost and demand response under the tiered carbon trading mechanism, the total operating cost of IES is reduced by 5.69% and the carbon emission is reduced by 17.06%, which significantly improves the reliability, economy and low carbon performance of IES.

G. Franzén, Håkan Garin

Geotechnical engineers have traditionally been focused on soil mechanics, rock mechanics and engineering geology. Thus it has been sufficient to master these topics to be recognized as a key participant in building and civil engineering projects. However, gradually concerns within both projects themselves and societies more generally are shifting towards new questions and challenges. Therefore, ensuring that geotechnical engineers remain central to all relevant projects, there is a need to master increasingly different and new ways of working together, obtaining new skills and increasing professionally pertinent knowledge and experience. This paper will give an overview of the issues geotechnical engineers have to address and master, if they are to take a lead in projects that seek to meet future challenges. This is really about working in a multi-disciplinary environment, using relevant technical methods without losing specifically engineering judgement, and then using open-minded communication skills to question previous practices that can proceed to find solutions to those future challenges identified. How is this to be done successfully within the profession? This paper offers some ideas. All professionals, and geotechnical engineers cannot be an exception, want to influence and contribute to solving current and future challenges, and thus we need to expand our knowledge awareness. The list of topics where we need to develop our knowledge is rather lengthy and include environmental considerations, contracts, law, conceptualisations of sustainability, robustness, monitoring, digitalisation, standardisation, and climate change. This paper will highlight two examples where geotechnical engineers with increased knowledge sensitivity and skills could make a significant contribution. First, there is an example from Göteborg about limiting a project impact within its zone of influence. Designing the geotechnical structure itself is only the first step, for in addition there is a need to control the building process, have sufficient monitoring, handling the expectations of society while ensuring recognition and use of a particular professional scope of operation. The other example concerns the re-use of material in our embankments to limit transportation. Which criteria should be used to determine the suitability of materials for re-use? How can we cope with societal reactions? Finally, the paper will discuss how geotechnical engineers, by combining geotechnical knowledge with new skills, can contribute with a sustainability foundation involving both relevant concepts and principles looking forward.

G. Shrivastava

This paper is a continuation of a history of the Department of Civil Engineering at The University of the West Indies (UWI) at St. Augustine. It thus extends an account of its formative decade 1961-1971 previously published (in 2013) in The West Indian Journal of Engineering. The three subsequent decades covered herein encompass milestones, and transformations: (a) beginning of graduate level research, (b) commencement of an MSc programme in Construction Engineering and Management, (c) change of name from Civil to ‘Civil and Environmental’ for embracing the heightened awareness of environmental concerns, (d) relocation into a purpose-built building with a floor space of approximately 5,000 m2, (e) construction of new environmental engineering, engineering geology, highway engineering, soil mechanics and structural engineering laboratories, (f) expansion and modernisation of the fluid mechanics laboratory, and (g) introduction of the semester system with its credit-based curriculum and assessment. Besides, there was a fivefold increase in student enrolment, followed by a sharp decline, and an increase in academic staff strength from six to twenty. This period also witnessed a gradual loss of regional diversity of its undergraduate students from a high of approximately 50 % in 1972 to less than 10% in 2001. On the other hand, there was a notable, and opposite, change in gender (female/male) ratio among the students – from less than 10%/90% in 1972 to approximately 50%/50% in 2001. Finally, the accreditation of the department’s degree programmes by the Engineering Council in the United Kingdom (UK), as well as the triennial visit of overseas external examiners, inherited from its inception, were maintained. Keywords: Civil Engineering; Coastal Engineering; Environmental Engineering; Education; History; University; West Indies

Tim Bolton, M. Patrick Decowski, Albert De Roeck et al.

This topical report of the 2021 US Community Study on the Future of Particle Physics (Snowmass 2021) summarizes the underground facilities needs for upcoming and next generation neutrino experiments. The underground facilities needs are discussed in the context of two broad categories: accelerator neutrinos, in particular with respect to the Deep Underground Neutrino Experiment (DUNE); and non-accelerator neutrinos, focusing on neutrinos from natural sources and on searches for neutrinoless double-beta decay.

Miroslav Vořechovský

The paper presents a new efficient and robust method for rare event probability estimation for computational models of an engineering product or a process returning categorical information only, for example, either success or failure. For such models, most of the methods designed for the estimation of failure probability, which use the numerical value of the outcome to compute gradients or to estimate the proximity to the failure surface, cannot be applied. Even if the performance function provides more than just binary output, the state of the system may be a non-smooth or even a discontinuous function defined in the domain of continuous input variables. In these cases, the classical gradient-based methods usually fail. We propose a simple yet efficient algorithm, which performs a sequential adaptive selection of points from the input domain of random variables to extend and refine a simple distance-based surrogate model. Two different tasks can be accomplished at any stage of sequential sampling: (i) estimation of the failure probability, and (ii) selection of the best possible candidate for the subsequent model evaluation if further improvement is necessary. The proposed criterion for selecting the next point for model evaluation maximizes the expected probability classified by using the candidate. Therefore, the perfect balance between global exploration and local exploitation is maintained automatically. The method can estimate the probabilities of multiple failure types. Moreover, when the numerical value of model evaluation can be used to build a smooth surrogate, the algorithm can accommodate this information to increase the accuracy of the estimated probabilities. Lastly, we define a new simple yet general geometrical measure of the global sensitivity of the rare-event probability to individual variables, which is obtained as a by-product of the proposed algorithm.