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

Mohammed Saleh Alshaikh

The performance of Organic Solar Cells (OSCs) is intrinsically linked to the molecular, electronic, and structural properties of donor and acceptor materials. This study employs various machine learning techniques, namely the Generalized Regression Neural Network (GRNN), Support Vector Machine (SVM), and Tree Boost, to predict key performance metrics of OSCs, including power conversion efficiency (PCE), short-circuit current density (JSC), open-circuit voltage (VOC), and fill factor (FF). The models are trained and evaluated using an experimentally reported dataset compiled by Sahu et al. Correlation analysis demonstrates that material characteristics such as polarizability, bandgap, dipole moment, and charge transfer are statistically associated with OSC performance. The predictive performance of the GRNN model is compared with that of the SVM and Tree Boost models, showing consistently lower prediction errors within the considered dataset. In addition, sensitivity analysis is performed to assess the relative importance of the predictor variables and to examine the influence of kernel functions on GRNN performance. The results indicate that machine learning models, particularly GRNN, can serve as effective data-driven tools for predicting the performance of organic solar cells and for supporting computational screening studies.

CHEN Ziquan 1 , HE Chuan 1, YU Bingxin 1, LI Zheng 1, 2, ZHANG Hang 2, LIU Maoyi 2

The long-term structural safety issues of water-rich tunnels under complex hydrogeological conditions during operation period and their mutual interaction mechanism with groundwater environment are receiving increasing attention. To study the evolution process of seepage and stress field of urban tunnels with small interval and propose reasonable waterproof-drainage methods, the model tests and numerical studies on seepage are carried out based on the Kexuecheng Tunnel in Chongqing City. The evolution process of water and earth pressure on the lining structures is revealed. Subsequently, a proactive control technology for groundwater environmental protection based on the collaborative regulation of drainage and structural safety is proposed. The results indicate that the precipitation funnels formed by the left and right holes of urba tunnels with a small interval partially overlap and affect each other in space. The water pressure exhibits a W-shaped distribution in the horizontal direction, gradually evolving into a concave arc shape as the burial depth increases or decreases. The horizontal influence range of the seepage field and stress field exceeds 80 meters. The reduction effects of grouting circle on water pressure and surrounding rock pressure decrease with the increase of water head height. When the water head height is 30~50 m, the reduction ratio of grouting circle to the total load is about 18.6%~40%. The distribution of earth and water pressure of tunnels with small interval shows significant asymmetry. Under heavy rainfall conditions, the evolution process of the total load on the lining can be divided into three stages: slow growth, rapid growth and gradual stability phase. The secondary lining cracking and water inrush disasters caused by high water pressure are mainly concentrated at the haunch, arch foot and bottom of tunnel. For high water pressure sections of urban tunnels with small interval, it is recommended to add drainage blind pipes at the inverted arch. In ecologically sensitive areas, the active regulation technology should be adopted for groundwater discharge in tunnels to protect the ecological balance of groundwater environment.

Suman Lata Yadav

The concept of life skills is related to the way of life that emphasises the mutual exchange of knowledge, attitudes, and interpersonal skills in education. Its objective is to develop diverse skills among students and prepare them to face life’s challenges with determination. The World Health Organization has defined life skills as “the positive behaviours and tendencies that enable a person to adapt in day-to-day life.” Life skills are the abilities that enable a person to adapt and exhibit positive behaviour, allowing them to deal effectively with the problems and challenges of daily life. Life is a unique gift. Therefore, by equipping life with various skills, happiness, peace, and prosperity are created. In this research, with the objectives of the study in mind, an analytical examination of life skills among secondary-level students has been conducted. This research study examines the effects of living conditions, gender, and social class on students’ life skills and presents the findings. Future researchers can build upon this, and other factors affecting the research can also be explored.

Shuai Zhao, Shi-Fan Wu, Dong-Ming Zhang et al.

This study investigated the potential use of microbially induced calcite precipitation (MICP) to prevent seepage in shield tunnels with the aim of decarbonizing tunnel engineering. An apparatus was developed to conduct scale model tests to evaluate the effectiveness of using MICP for shield tunnel seepage control. To understand the MICP process and its induced change in seepage flow rate, a series of 1-g physical model tests were conducted using the designed apparatus to investigate the effect of injection methods, grouting pressure, and calcium carbonate (CaCO3) content produced as well as its distribution on the reduction of seepage flow rate for thephysical tunnel model with different backfills behind its linings. The variation law of the pore pressure near grouting hole of the tunnel segment was also revealed. Results indicated that when the amount of CaCO3 precipitation in sand-grout mixtures was 10.53% and 10.12%, water seepage flow rate for thephysical tunnel modelwith Fujian- and coarse-sand-grout backfill respectively reduced by 94.3% and 73.8% of their respective initial values, and S-wave velocity increased by 89.6% and 84.9% for Fujian- and coarse-sand-grout mixture, respectively. The grouting pressure needed to be controlled within a certain range to prevent the unstable CaCO3 precipitates from being washed away. The testing results also showed that the one-phase injection method was more effective in controlling seepage water into a shield tunnel. Based on the findings of the scale model tests, some vital considerations and suggestions were presented on the use of MICP approaches for shield tunnel seepage control.

Margaret Hawton

We second quantize the Fermi Lagrangian in the Lorenz gauge to obtain a covariant theory of photon quantum mechanics. Number density is real so it is interpreted as position probability density. The Hilbert space is the vector space of fields with norm 1 describing physical photons and the Poincare operators are extended to include position to represent observables. A photon continuity equation is derived that describes creation, propagation and annihilation of photons in an optical circuit. The relationship to orthodox quantum mechanics is discussed.

Petro Voloshyn, Yurii Andreichuk, Valentyna Marusyak

The purpose of this research is to conduct a predictive assessment of the impact of hazardous geodynamic processes on underground construction in the central part of Lviv. These processes are linked to specific geological structures, hydrogeological conditions, unique rock properties, and the chemical composition of groundwater. Relevance of work. In Lviv and many other large cities in Ukraine, transportation and parking problems are extremely acute. They are especially relevant for the central part of the city, which is characterised by a dense network of narrow streets, extreme vehicle saturation, dense buildings, and numerous transportation attractions. Their design and construction require detailed information about the structure, composition, and properties of the geological environment, as well as the geological risk assessment associated with the construction and operation of such structures. Research methods. Information on geological conditions, composition, physical, mechanical, filtration, and corrosion properties of soils, the aggressiveness of groundwater, design features of structures, types of foundations, and experience in constructing underground trams has been collected and comprehensively analysed. More than 50 experimental wells were specially drilled, and geophysical, engineering, geodetic, and laboratory studies were performed. Computer cartographic models of the geological environment were also built. Results. Based on the data obtained, the geological structure, hydrogeological conditions, physical and mechanical properties of the soils, and morphodynamic processes in the central part of the city are characterised. A spatial analysis of the risk-forming components of the geological environment is conducted, and the risks associated with its construction development are assessed. Scientific novelty. Various types of risk-forming factors for underground construction in the central part of Lviv have been identified. These factors include: geological factors that encompass structure of the rock massif, composition and condition of the rocks, their physical, mechanical and seismic properties, as well as their vulnerability to external influence; hydrogeological factors that involve the number of aquifers, depth of groundwater, their chemical composition and aggressiveness toward building structures, pressure level and the relationship between aquifers; morphodynamic factors that relate to the speed of modern tectonic movements and the development of suffosion processes and deformations of the Earth's surface. For the first time, a predictive assessment of geological risks associated with underground construction in various areas of the study region has been provided. Practical significance. The results obtained will make it possible to ensure the rational spatial location of underground parking lots and other objects of underground urbanization, to choose effective construction technologies that provide minimal risks for the stability of the designed structures and adjacent buildings and engineering infrastructure and will also serve as an information base for predicting the negative consequences of the construction and operation of underground structures in the long term.

N. Rengers, Jan Reinout Jan Reinout HJR. Deketh Deketh, Robert Robert Hrgk Hack Hack et al.

L. Mase, Thomas Mustafa Kamal, Melly Zuhadjar Putri et al.

Yu Zhang, Lianjin Tao, Xu Zhao et al.

For the project of pipe jacking in cohesionless soil, it is key to determine the vertical load on jacked pipe so as to predict the jacking force accurately. In this paper, a new parabolic soil arching model was proposed to calculate the vertical load on jacked pipe. This proposed analytical model was composed of parabolic soil arching zone, parabola-typed collapse zone and friction arch zone. Combined with existing literature, the key parameters (i.e., height of parabolic soil arching, horizontal pressure coefficient and width and height of friction arch) were determined. In addition, considering that the trajectory of major stress is parabola, the formula of horizontal pressure coefficient was deduced in the friction arch. The parabolic soil arching zone is assumed as a three-hinged arch with reasonable arch axis, and the formula of load transfer was derived considering the transition effect of parabolic soil arching. The results of experiment, theoretical models and numerical model were adopted to verify the proposed analytical model. Finally, the influence of the key parameters on the vertical load on jacked pipe were also discussed in detail. This work provides a meaningful reference for evaluating the vertical load on jacked pipe for design of pipe jacking.

Marcus Kessel, Colin Atkinson

The ability of Generative AI (GAI) technology to automatically check, synthesize and modify software engineering artifacts promises to revolutionize all aspects of software engineering. Using GAI for software engineering tasks is consequently one of the most rapidly expanding fields of software engineering research, with over a hundred LLM-based code models having been published since 2021. However, the overwhelming majority of existing code models share a major weakness - they are exclusively trained on the syntactic facet of software, significantly lowering their trustworthiness in tasks dependent on software semantics. To address this problem, a new class of "Morescient" GAI is needed that is "aware" of (i.e., trained on) both the semantic and static facets of software. This, in turn, will require a new generation of software observation platforms capable of generating large quantities of execution observations in a structured and readily analyzable way. In this paper, we present a vision and roadmap for how such "Morescient" GAI models can be engineered, evolved and disseminated according to the principles of open science.

Xiaoqing Feng, Bin Ye, Jie He et al.

Sand liquefaction is a process in which the excess pore water pressure of saturated sand soils increases and the effective stress of saturated sand decreases under the action of vibration, resulting in the transition of sand soils from the solid state to the liquid state. In this paper, an underwater sand slope model containing the upper sand slope and the bottom non-liquefied clay layer was designed. The whole process of large deformation of flow liquefaction from the solid state to the liquid state was reproduced by the shaking table test and recorded by the high-definition particle image velocimetry (PIV) equipment. Four main influencing factors: the acceleration amplitude of the shaking table, the frequency of the shaking table, the relative density of the sand slope, and the slope ratio of height and width of the sand slope, were considered. During the test, the dynamic response characteristics of acceleration and excess pore water pressure (EPWP) within the underwater sand slope model were monitored and analyzed in the whole deformation process to reveal the mechanism of the sand liquefaction process and the law of development and provide data support for subsequent research.

Huy T. Q. Phan, Duc M. Bui, Cong T. Than et al.

Fractals are ubiquitous natural emergences that have gained increased attention in engineering applications, thanks to recent technological advancements enabling the fabrication of structures spanning across many spatial scales. We show how the geometries of fractals can be exploited to determine their important mechanical properties, such as the first and second moments, which physically correspond to the center of mass and the moment of inertia, using a family of complex fractals known as the dragons.

P. E. Brandyshev, Yu. A. Budkov

In this paper, we introduce a statistical field theory that describes the macroscopic mechanical forces in inhomogeneous Coulomb fluids. Our approach employs the generalization of Noether's first theorem for the case of fluctuating order parameter, to calculate the stress tensor for Coulomb fluids. This tensor encompasses the mean-field stress tensor and the fluctuation corrections derived through the one-loop approximation. The correction for fluctuations includes a term that accounts for the thermal fluctuations of the local electrostatic potential and field in the vicinity of the mean-field configuration. This correlation stress tensor determines how electrostatic correlation affects local stresses in a nonuniform Coulomb fluid. We also use previously formulated general covariant methodology [P.E. Brandyshev and Yu.A. Budkov, J. Chem. Phys. 158, 174114 (2023)] in conjunction with a functional Legendre transformation method and derive within it the same total stress tensor. We would like to emphasize that our general approaches are applicable not only to Coulomb fluids but also to nonionic simple or complex fluids, for which the field-theoretic Hamiltonian is known as a functional of the relevant scalar order parameters.

N. Trinh

"Many rock engineering projects today may face rock mechanics challenges such as particularly complicated geometry or excavation plan, and complicated geological conditions. There may be no similar existing experience to lean on. Thus, empirical methods have limitations and uncertainties in such cases. Therefore, SINTEF has developed a reliable rock engineering tool to deal with the challenges. The tool is a combination of Investigation, Numerical modelling, and Monitoring. We use the term “SINTEF-TRIPOD” for the methodology. This paper presents the application of the SINTEF-TRIPOD for few important infrastructure projects in Oslo, which are Follo Line metro project and a water supply project."

S. Subedi, M. Panta, Uttam Lamsal

Gang Cheng, Wentao Xu, Bin Shi et al.

Understanding the spatiotemporal evolution of overburden deformation during coal mining is still a challenge in engineering practice due to the limitation of monitoring techniques. Taking the Yangliu Coal Mine as an example, a similarity model test was designed and conducted to investigate the deformation and failure mechanism of overlying rocks in this study. Distributed fiber optic sensing (DFOS), high-density electrical resistivity tomography (HD-ERT) and close-range photogrammetry (CRP) technologies were used in the test for comprehensive analyses. The combined use of the three methods facilitates the investigation of the spatiotemporal evolution characteristics of overburden deformation, showing that the mining-induced deformation of overburden strata was a dynamic evolution process. This process was accompanied by the formation, propagation, closure and redevelopment of separation cracks. Moreover, the key rock stratum with high strength and high-quality lithology played a crucial role in the whole process of overburden deformation. There were generally three failure modes of overburden rock layers, including bending and tension, overall shearing, and shearing and sliding. Shear failure often leads to overburden falling off in blocks, which poses a serious threat to mining safety. Therefore, real-time and accurate monitoring of overburden deformation is of great significance for the safe mining of underground coal seams.

João Carlos Baptista Jorge da Silva

O presente trabalho apresenta a célula K0-UFBa, onde é mostrado um dispositivo eficiente para a determinação do coeficiente de empuxo no repouso de solos a partir de amostras indeformadas. A célula K0-UFBa foi desenvolvida e licenciada no LabGeo da Escola Politécnica da Universidade Federal da Bahia (UFBa), Brasil. Seus principais componentes e detalhes de montagem são mostrados. O desenvolvimento do equipamento baseou-se nos ensaios de odômetro, porém com confinamento lateral de água, que por ser incompressível, não permite deformação neste sentido, mantendo a condição de K0. A fim de avaliar os resultados da célula K0 em amostras indeformadas obtidas de dois poços escavados em solo residual, esses resultados foram comparados com os ensaios DMT, que foram feitos próximo aos poços. Os resultados mostraram comportamento semelhante ao longo da profundidade em ambas às áreas de ensaio quando comparados com os resultados da célula K0 e ensaios de campo (DMT). A pequena variação dos valores deve-se principalmente à heterogeneidade do solo residual, associada a fatores como erosão superficial, cimentação devido à presença de óxidos e histórico de tensões originadas da rocha mãe.

Donghui Chen, Huie Chen, Wen Zhang et al.

The equivalent elastic modulus is a parameter for controlling the deformation behavior of fractured rock masses in the equivalent continuum approach. The confining stress, whose effect on the equivalent elastic modulus is of great importance, is the fundamental stress environment of natural rock masses. This paper employs an analytical approach to obtain the equivalent elastic modulus of fractured rock masses containing random discrete fractures (RDFs) or regular fracture sets (RFSs) while considering the confining stress. The proposed analytical solution considers not only the elastic properties of the intact rocks and fractures, but also the geometrical structure of the fractures and the confining stress. The performance of the analytical solution is verified by comparing it with the results of numerical tests obtained using the three-dimensional distinct element code (3DEC), leading to a reasonably good agreement. The analytical solution quantitatively demonstrates that the equivalent elastic modulus increases substantially with an increase in confining stress, i.e. it is characterized by stress-dependency. Further, a sensitivity analysis of the variables in the analytical solution is conducted using a global sensitivity analysis approach, i.e. the extended Fourier amplitude sensitivity test (EFAST). The variations in the sensitivity indices for different ranges and distribution types of the variables are investigated. The results provide an in-depth understanding of the influence of the variables on the equivalent elastic modulus from different perspectives.

Chengyu Xie, Hoang Nguyen, Xuan-Nam Bui et al.

Due to the rapid industrialization and the development of the economy in each country, the demand for energy is increasing rapidly. The coal mines have to pace up the mining operations with large production to meet the energy demand. This requirement has led underground coal mines to go deeper with more difficult conditions, especially the mining hazards, such as large deformations, rockburst, coal burst, roof collapse, to name a few. Therefore, this study aims at investigating and predicting the stability of the roadways in underground coal mines exploited by longwall mining method, using various novel intelligent techniques based on physics-based optimization algorithms (i.e. multi-verse optimizer (MVO), equilibrium optimizer (EO), simulated annealing (SA), and Henry gas solubility optimization (HGSO)) and adaptive neuro-fuzzy inference system (ANFIS), named as MVO-ANFIS, EO-ANFIS, SA-ANFIS and HGSO-ANFIS models. Accordingly, 162 roof displacement events were investigated based on the characteristics of surrounding rocks, such as cohesion, Young's modulus, density, shear strength, angle of internal friction, uniaxial compressive strength, quench durability index, rock mass rating, and tensile strength. The MVO-ANFIS, EO-ANFIS, SA-ANFIS and HGSO-ANFIS models were then developed and evaluated based on this dataset for predicting roof displacements in roadways of underground mines. The results indicated that the proposed intelligent techniques could accurately predict the roof displacements in roadways of underground mines with an accuracy in the range of 83%–92%. Remarkably, the SA-ANFIS model yielded the most dominant accuracy (i.e. 92%). Based on the accurate predictions from the proposed techniques, the reinforced solutions can be timely suggested to ensure the stability of roadways during exploiting coal, especially in the underground coal mines exploited by the longwall mining.

David Wallace

Through extended consideration of two wide classes of case studies -- dilute gases and linear systems -- I explore the ways in which assumptions of probability and irreversibility occur in contemporary statistical mechanics, where the latter is understood as primarily concerned with the derivation of quantitative higher-level equations of motion, and only derivatively with underpinning the equilibrium concept in thermodynamics. I argue that at least in this wide class of examples, (i) irreversibility is introduced through a reasonably well-defined initial-state condition which does not precisely map onto those in the extant philosophical literature; (ii) probability is explicitly required both in the foundations and in the predictions of the theory. I then consider the same examples, as well as the more general context, in the light of quantum mechanics, and demonstrate that while the analysis of irreversibility is largely unaffected by quantum considerations, the notion of statistical-mechanical probability is entirely reduced to quantum-mechanical probability.