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

YAN Xusheng1, 2 , WANG Qiong1, 2 , SU Wei1, 2, YE Weimin1, 2, ZHANG Fengshou1, 2, LIU Yichun1, 2

To investigate the swelling properties and microstructure evolution of compacted bentonite in an annular technological void under different temperatures, swelling pressure tests are conducted on compacted bentonite in an annular technological void. After technological void is closed, water content, dry density and microstructures is determined, respectively. Results show that the swelling pressure time-history curve shows a single-peak pattern, initially rising to the peak before falling and stabilizing. The dynamic equilibrium of the "wedge" force, formed by the thickening of bound water film, laminar cleavage, pore collapse and thickening of diffusion double layers, dominates the force states from the vertical lateral limit to the constant volume. Higher temperatures intensify the increase water content and decrease dry density from the interior to the exterior. The swelling behavior is enhanced by the increase in montmorillonite expansive coefficient and water molecule diffusive coefficient with temperature, leading to more inter-assemblage pores being occupied by the swollen matrix. At higher temperatures, more water molecules entered the interlayers, causing higher hydration reactions, lamellar cleavage, and pore collapse, which reduced the total void ratio and enhanced the swelling properties.

GENG Jiabo, ZHANG Hong, ZHENG Siying et al.

Water inrush disaster is one of the most threatening disasters in the process of deep coal mining, coal under the action of mining stress to produce damage fractures to form seepage paths, groundwater through these seepage paths into the working face to cause water inrush disasters, different mining methods caused by different damage degrees and fracture distribution, resulting in different distribution of seepage paths, directly affecting the risk of water inrush. Therefore, the damage characteristics and seepage path distribution of deep coal under three mining modes: protective layer mining (PCM), top coal mining (TCM) and pillarless mining (NM) were systematically studied through the triaxial seepage test with axial and confining pressure cycles, and the three-dimensional fracture scanning with a high-precision scanner. The results show that the high stress loading amplitude (NM>TCM>PCM) significantly aggravates the deformation of coal samples and drives the hysteresis loop to change from sparse to divergent, and the strain mutation of TCM and NM in the late cycle indicates the risk of instability. The damage accumulation rate of TCM and NM was significantly higher than that of PCM, and the damage degree of the rupture surface became more serious. The permeability increased in stages with the increase of stress level, and the high stress loading amplitude promoted the fracture propagation and penetration, which significantly optimized the connectivity of the seepage channel. The seepage paths of PCM, TCM and NM showed bifurcation tree, network and surface shape, respectively, and the seepage effect increased sequentially. This study provides a reference for the damage control and prevention of water inrush in deep coal.

Ankur Abhishek, Anasua GuhaRay, Toshiro Hata

Black cotton soil (BCS) poses significant complexities in geotechnical applications due to its swelling and shrinkage behavior. It causes significant economic losses globally due to reconstruction and rehabilitation efforts. Reliable soil reinforcement techniques are, therefore, essential to mitigate the deleterious effects of expansive BCS and to ensure the long-term stability of the structures built upon them. The present study explores the application of rice husk ash (RHA) to BCS using nitrogen (N2) gas adsorption techniques such as Brunauer–Emmett–Teller (BET), Langmuir, and adsorption isotherm analyses. These techniques are based on the principle that N2 gas is adsorbed onto the reactive surface sites. The surface of BCS is considered reactive due to its high clay content and the presence of montmorillonite. With the addition of RHA, pozzolanic reactions progress, leading to the development of cementitious phases such as calcium silicate hydrate (C-S-H), which gradually fill these reactive surface sites, leading to a decrease in the material’s gas adsorption capacity. This reduction in N2 gas adsorption provides a measurable indication of pozzolanic activity, allowing for a more detailed microstructural assessment of stabilized soil systems. A sharp reduction in N2 gas adsorption was observed in BET, Langmuir, and adsorption isotherm analyses at 6 % RHA content, conducted on 28-day cured Unconfined compressive strength (UCS)-tested samples. BET results showed a reduction in adsorption from 0.0635 mg/g for untreated BCS to 0.0385 mg/g at 6 % RHA concentration. This 6 % RHA content also corresponds with peak mechanical performance observed in UCS, California bearing ratio (CBR), indirect tensile strength (ITS), and cone penetration test (CPT), highlighting a strong correlation between microstructural improvement and engineering behavior. The UCS of untreated BCS (183 kPa) increased to a maximum of 819 kPa after 7 days and 1370 kPa after 28 days of curing, confirming 6 % RHA as the optimum dosage.

Mehran Ebrahimi, Masayuki Yano

We introduce a hyperreduced reduced basis element method for model reduction of parameterized, component-based systems in continuum mechanics governed by nonlinear partial differential equations. In the offline phase, the method constructs, through a component-wise empirical training, a library of archetype components defined by a component-wise reduced basis and hyperreduced quadrature rules with varying hyperreduction fidelities. In the online phase, the method applies an online adaptive scheme informed by the Brezzi-Rappaz-Raviart theorem to select an appropriate hyperreduction fidelity for each component to meet the user-prescribed error tolerance at the system level. The method accommodates the rapid construction of hyperreduced models for large-scale component-based nonlinear systems and enables model reduction of problems with many continuous and topology-varying parameters. The efficacy of the method is demonstrated on a two-dimensional nonlinear thermal fin system that comprises up to 225 components and 68 independent parameters.

Dibyayan Patra, Pasindu Ranasinghe, Bikram Banerjee et al.

Rock bolts are crucial components of the subterranean support systems in underground mines that provide adequate structural reinforcement to the rock mass to prevent unforeseen hazards like rockfalls. This makes frequent assessments of such bolts critical for maintaining rock mass stability and minimising risks in underground mining operations. Where manual surveying of rock bolts is challenging due to the low light conditions in the underground mines and the time-intensive nature of the process, automated detection of rock bolts serves as a plausible solution. To that end, this study focuses on the automatic identification of rock bolts within medium to large-scale 3D point clouds obtained from underground mines using mobile laser scanners. Existing techniques for automated rock bolt identification primarily rely on feature engineering and traditional machine learning approaches. However, such techniques lack robustness as these point clouds present several challenges due to data noise, varying environments, and complex surrounding structures. Moreover, the target rock bolts are extremely small objects within large-scale point clouds and are often partially obscured due to the application of reinforcement shotcrete. Addressing these challenges, this paper proposes an approach termed DeepBolt, which employs a novel two-stage deep learning architecture specifically designed for handling severe class imbalance for the automatic and efficient identification of rock bolts in complex 3D point clouds. The proposed method surpasses state-of-the-art semantic segmentation models by up to 42.5% in Intersection over Union (IoU) for rock bolt points. Additionally, it outperforms existing rock bolt identification techniques, achieving a 96.41% precision and 96.96% recall in classifying rock bolts, demonstrating its robustness and effectiveness in complex underground environments.

Chuang Zhao, Yongzheng Wang, Shuangqing Sheng

Stress wave propagation is an important branch in the field of rock mechanics, and the dynamic stability analysis of rock engineering is built upon the research foundation of stress wave propagation theory. As one of the significant disciplinary branches of rock mechanics, stress wave propagation theory is characterized by its typical interdisciplinary nature, playing a leading role in the safe development of urban construction and underground engineering under deep high stress. With the continuous development of the country and society, major national engineering construction facilities are in full swing, which also poses new requirements for the dynamics of rock engineering. This book consists of six chapters, adopting two primary analytical methods: the equivalent continuum medium method and the displacement discontinuity method. Combining numerical simulations and experimental validations, egarding macroscopic joints and microscopic fractures in rock masses, it explore and predict the propagation characteristics and laws of stress waves in jointed and fractured rock masses. Regarding the dynamic constitutive relations of stress waves in rock masses, a uniform. discontinuity analysis method is proposed and referenced. It is found that joints and fractures hinder the propagation of stress waves, leading to their attenuation and reflection. Therefore, the propagation laws of stress waves in macro-jointed rock masses and meso-fractured rock masses are thoroughly investigated. The aim is to help readers better understand the practical significance of stress wave propagation theory and analytical methods in jointed and fractured rock masses.

Xin Huang, Miaoyuan Tang, Shuaifeng Wang et al.

The widespread utilisation of tunnel boring machines (TBMs) in underground construction engineering requires a detailed investigation of the cutter-rock interaction. In this paper, we conduct a series of large-scale standing rotary cutting tests on granite in conjunction with high-fi delity numerical simulations based on a particle-type discrete element method (DEM) to explore the effects of key cutting parameters on the TBM cutter performance and the distribution of cutter-rock contact stresses. The assessment results of cutter performance obtained from the cutting tests and numerical simulations reveal similar dependencies on the key cutting parameters. More speci fi cally, the normal and rolling forces exhibit a positive correlation with penetration but are slightly in fl uenced by the cutting radius. In contrast, the side force decreases as the cutting radius increases. Additionally, the side force shows a positive relationship with the penetration for smaller cutting radii but tends to become negative as the cutting radius increases. The cutter's relative effectiveness in rock breaking is signi fi cantly impacted by the penetration but shows little dependency on the cutting radius. Consequently, an optimal penetration is identi fi ed, leading to a low boreability index and speci fi c energy. A combined Hertz-Weibull function is developed to fi t the cutter-rock contact stress distribution obtained in DEM simulations, whereby an improved CSM (Colorado School of Mines) model is proposed by replacing the original monotonic cutting force distribution with this combined Hertz-Weibull model. The proposed model outperforms the original CSM model as demonstrated by a comparison of the estimated cutting forces with those from the tests/ simulations. The fi ndings from this work that advance our understanding of TBM cutter performance have important implications for improving the ef fi ciency and reliability of TBM tunnelling in granite. © 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Honghu Zhu, Yuanxu Huang, Haihong Song et al.

Abstract Biochar is a carbon sink material with the potential to improve water retention in various soils. However, for the long‐term maintenance of green infrastructure, there is an additional need to regulate the water contents in the covers to maintain vegetation growth in semiarid conditions. In this study, biochar‐amended soil was combined with subsurface drip irrigation, and the water preservation characteristics of this treatment were investigated through a series of one‐dimensional soil column tests. To ascertain the best treatment method specific to semiarid climatic conditions, the test soil was amended with 0%, 1%, 3%, and 5% biochar. Automatic irrigation devices equipped with soil moisture sensors were used to control the subsurface water content with the aim of enhancing vegetation growth. Each soil column test lasted 150 h, during which the volumetric water contents and soil suction data were recorded. The experimental results reveal that the soil specimen amended with 3% biochar is the most water‐saving regardless of the time cost. Soil with a higher biochar content (e.g., 5%) consumes a more significant amount of water due to the enhancement of the water‐holding capacity. Based on the experimental results, it can be concluded that the appropriate ratio can be determined within 1%–3%, which can reduce not only the amount of irrigated/used water but also the time cost. Such technology can be explored for water content regulation in green infrastructure and the development of barriers for protecting the environment around deep underground waste containment.

Roberto Casadei, Gianluca Aguzzi, Giorgio Audrito et al.

Today's distributed and pervasive computing addresses large-scale cyber-physical ecosystems, characterised by dense and large networks of devices capable of computation, communication and interaction with the environment and people. While most research focusses on treating these systems as "composites" (i.e., heterogeneous functional complexes), recent developments in fields such as self-organising systems and swarm robotics have opened up a complementary perspective: treating systems as "collectives" (i.e., uniform, collaborative, and self-organising groups of entities). This article explores the motivations, state of the art, and implications of this "collective computing paradigm" in software engineering, discusses its peculiar challenges, and outlines a path for future research, touching on aspects such as macroprogramming, collective intelligence, self-adaptive middleware, learning, synthesis, and experimentation of collective behaviour.

Marek Żukowski, Marcin Markiewicz

In June 1925 Heisenberg arrived at Helgoland/Heligoland island to escape a fit of hay fever. He returned with a sketch of a strange theory of the micro-world, which we now call quantum mechanics. This essay attempts to present a look at this theory, which tries to return to the original insight of Heisenberg on what should be the essence of a theory of atomic realm: it must be a theory of the observable events, in which fundamentally unobservable quantities have no place. No ontological status is given to elements of the mathematical formulation of the theory. The theory is about our description of events in laboratories, probabilities of which are given by the Born rule. Following Bohr, these events involve macroscopic measuring apparatuses, and the accessible final events are classically describable. Information about the events is cloneable, as it is of a classical nature. The modern quantum theory of classicality is the decoherence theory. It treats "the pointer variable" of measuring apparatus as an open system interacting with an environment consisting of all other "zillions" of degrees of freedom of the device, and anything coupled to it. Because such environment is uncontrollable we have no possibility to reverse measurements. The quantum mechanical measurement theory based on decoherence theory is reproducing the predictions of Born rule. Notwithstanding, possibility of reversing measurements and of application of Born rule in situations other than these which lead to macroscopically observable events are features of a modification of quantum mechanics which is called by its adherents "unitary quantum mechanics". As its predictions, which go beyond quantum mechanics, are not testable - we claim that unitary quantum mechanics in an interpretation of quantum mechanics. As such it is metaphysics.

B. Yang, Y. Li, E. Ambah et al.

definition /def-i-ni-tion/ noun a statement of the meaning of a word, commonly found in a dictionary. Every discipline has its own language – domain specific terminology that allows practitioners to better understand the problem and communicate with one another. While some words and phrases are only found in one specific discipline, there are others that are found in a variety of related disciplines and subdisciplines. Examples in disciplines related and/or adjacent to rock engineering include the terms validation (which has differing definitions in machine learning compared to numerical modelling) and fines (which has differing definitions in soil mechanics compared to cave mining). Confusion may arise when these terms with differing discipline definitions are not defined in their specific context in the literature. Adding to this confusion is the misuse of certain terms in rock engineering, such as accuracy, precision, and quantifying. The goal of this paper is to clarify the definitions of rock engineering terms that are found in other related disciplines, as well as clarify the definitions of rock engineering specific terms. By providing this dictionary of rock engineering terms, we hope to standardize rock engineering vocabulary, allowing for clearer communication among practitioners and students. For any rock engineers who competed in spelling bees in their childhood, the phrase "definition please" may ring a bell. During spelling bees, contestants are able to ask for the definition of a word ("definition please?") to help them spell it. While spelling bees are no longer an aspect of our lives after elementary school, asking for the definition of a word remains an important aspect of research and professional development. Every discipline has its own language – domain specific terminology that allows practitioners to understand the problem in greater detail and to better communicate with one another. Rock engineering language consists of its own terminology (such as rock mass rating or geological strength index) and terminology overlapping with other disciplines, such as with soil mechanics, statistics, and numerical modelling. Confusion may arise when terms are not defined in their specific context, especially those overlapping with other disciplines. This confusion is further exacerbated by the tendency of rock engineers to both misuse certain terminology (such as accuracy, precision, and quantity) and use others interchangeably when they do not have the same definition (such as imbalanced data/skewed data and calibration/validation). As a result, there is a clear need to clarify the definitions of certain rock engineering terms.

Youxin Zhou, Rong Yang, Maogui Jing et al.

Ensuring the safety and excavation efficiency of pumped storage power stations (PSPs) requires a focus on stability in the construction and design of underground cavern groups, along with the implementation of intelligent safety analysis and warning systems. This paper primarily focuses on the application of this system in Tiantai PSPs and highlights stability issues that may arise from uncertainties like joint fractures or poor rock conditions resulting in untimely support during construction. To accurately measure rock mass mechanics parameters, the paper recommends utilizing various mechanical responses of surrounding rocks and employing inverse analysis techniques for material parameter inversion. Additionally, the paper examines the deformation and stability effects caused by different factors such as lagged support and geological conditions through a case study that demonstrate support reinforcement practices at the powerhouse end. The paper also discusses suggested measures for dealing with these issues. Ultimately, this approach helps ensure both the safety and efficiency of the construction and operation of underground caverns while minimizing potential environmental and community impact.

Великанов Петр Геннадьевич, Артюхин Юрий Павлович

Определение собственных и вынужденных колебаний рамных конструкций, моделируемых стержнями с распределенными массами (бесконечное число степеней свободы), довольно затруднительно. Поэтому в статье модель рамы наделяют конечным числом степеней свободы: массу помещают в некоторое число узлов, которые упруго взаимодействуют со стержнями, не имеющими массы. Стержни работают только на изгиб. Продольные перемещения не учитываются, так как частота продольных колебаний на два порядка выше частоты изгибных колебаний. Такая модель позволяет составить выражения кинетической и потенциальной энергии и затем с помощью уравнений Лагранжа 2-го рода получить систему дифференциальных уравнений колебаний многоэтажных зданий. В статье с использованием функций Грина, матриц жесткости, масс, податливости и др. была решена задача о свободных колебаниях Г-образной рамы. Полученные приближенные результаты при сравнении с малоизвестными точными результатами показали хорошую сходимость, особенно при увеличении числа степеней свободы (количества сосредоточенных масс, моделирующих распределенную массу стержней Г-образной рамы).

QIU Dapeng 1, 2, CHEN Jianyun 3, WANG Wenming 1, 2, CAO Xiangyu 4

The increase dynamic analysis (IDA) curves of seismic responses of the underground large-scale frame structure (ULSFS) are investigated during the single horizontal earthquakes and horizontal-vertical earthquakes, respectively. The influence mechanism of vertical earthquakes on the seismic responses of different vulnerable positions is revealed. Aiming at the interlayer drift deformation and flexural deformation in the ULSFS, the interlayer drift ratio (IDR) and interlayer rotation angle (IRA) are employed as the seismic performance evaluation indexes. Therefore, the influence mechanism of vertical earthquakes on structural seismic performance is further revealed. The seismic fragility curves of the ULSFS are achieved during horizontal earthquakes and horizontal-vertical earthquakes, respectively. The results show that the vertical earthquakes have small seismic influences on the seismic fragility of the ULSFS based on the IDR. However, the vertical earthquakes enlarge the local flexural deformation of the ULSFS and decrease the seismic performance of the ULSFS based on the IRA. The seismic fragility considerably increases after considering the vertical seismic effects. The IDR aiming at the horizontal drift deformation and the IRA aiming at the interlayer flexural deformation are advised to be employed to assess the seismic fragility of large underground structures during both horizontal and vertical earthquakes comprehensively.

AN Yijing , HAN Pengju , QIN Jiandong , BAI Xiangling , HE Bin , WANG Xiaoyuan

In order to study the seismic response of the leaning pagoda under soil-structure interaction, two kinds of finite element models for the leaning and un-leaning Wenfeng Pagoda of Yongzuo Temple are established by using the ABAQUS finite element software, adopting the equivalent linearization of foundation soils and non-linearization of masonry materials, considering the geometric non-linearities of the soil-structure separation and slip, and adding the visco-elastic artificial boundaries with the help of python language. By comparing the two models through the time-range analysis method, the effects of inclination factor on the seismic performance of the pagoda are investigated. The results show that under the action of small earthquakes, the historical maximum tilt has less impact on its seismic performance, and the peak displacement, section displacement angle and acceleration amplification coefficient have small increase. Under the action of middle earthquakes, the residual displacement of the leaning pagoda increases greatly, the lower layer of the pagoda section displacement angle is generally enlarged, the acceleration amplification coefficient increases, the damage area and degree of the pagoda in the leaning side increase dramatically, and the foundation damage should not be neglected. The analysis results can provide a reference for the seismic protection of similar leaning high-rise dense eaves brick pagodas.

Sadegh Pourghasemi Hanza, Hamed Ghafarirad

In this study, an inhomogeneous Cosserat rod theory is introduced and compared to the conventional homogeneous rod for modeling soft manipulators. The inhomogeneity is addressed by considering the pressure actuation as part of the rod's constitutive laws, resulting in shifting the neutral axis. This shift is investigated for a soft manipulator with three parallel fiber-reinforced actuators. Furthermore, a fiber-reinforced actuator is modeled using nonlinear continuum mechanics to extract the effect of radial pressure on axial deformation and is combined with Cosserat model. Finally, several numerical methods are employed to solve the proposed model and validated by a series of experiments.

Jakub A. Kochanowski, Bobby Carroll, Merrill E. Asp et al.

Bacteria build multicellular communities termed biofilms, which are often encased in a self-secreted extracellular matrix that gives the community mechanical strength and protection against harsh chemicals. How bacteria assemble distinct multicellular structures in response to different environmental conditions remains incompletely understood. Here, we investigated the connection between bacteria colony mechanics and the colony growth substrate by measuring the oscillatory shear and compressive rheology of bacteria colonies grown on agar substrates. We found that bacteria colonies modify their own mechanical properties in response to shear and uniaxial compression with the increasing agar concentration of their growth substrate. These findings highlight that mechanical interactions between bacteria and their microenvironment are an important element in bacteria colony development, which can aid in developing strategies to disrupt or reduce biofilm growth.

YU Jin 1, YAO Wei 1, REN Wen-bing 2, FAN Zhi-zhong 3, QIN Wei 4

In order to explore its deformation and failure laws under cyclic disturbance, a series of uniaxial tests of marble with different stress levels and cyclic amplitudes are carried out. The research results show that: (1) The stress level is the decisive factor whether the marble specimens tend to failure or not, and the cyclic amplitude is a relatively minor factor. When the stress level just reaches the dilation one, the rock specimen can not fail even if it is under a much larger cyclic amplitude. When the stress level is much higher than the dilation stress and the cyclic amplitude is given a much larger value, the rock will rapidly fail. (2) Compared with the irreversible deformation, the dynamic stiffness can better reflect the transition features of sparse-dense-sparse stages. The positive and negative values of decay rate of the dynamic stiffness can be used as the features of failure precursor, and the rock failure can be predicted at the stable deformation stage. (3) For the failed marble specimens, the damage variable based on the dynamic stiffness characterization is similar to the general trend of irreversible deformation. The double-high mode is consistent with the type Ⅰ curve, and the rest of the curves are consistent with the type Ⅱ curve.

Krzysztof Fuławka, Piotr Mertuszka, Witold Pytel et al.

In this paper, selected methods of destress blasting efficiency assessment are presented, and novel quantitative methods based on in situ seismic measurements are proposed. The newly formulated solution combines two different approaches. The first, which is useful mostly for the near-field seismic analyses, is based on the analysis of seismic amplitude characteristics, and the second, relevant for far-field evaluation, is extended by the duration and frequency of the seismic wave. Both approaches are based on the seismic analyses of the waveforms generated by blasting recorded by the local seismic network. The proposed solutions are tested and validated in deep underground mines in Poland in which the room-and-pillar mining method is applied. Based on performed analysis, it is shown that both methods may be used as a rockburst hazard control in underground mines. However, developed methods may also be successfully implemented in other engineering practices, including the assessment of seismic vibrations in open pits and quarries.

H.C. Nguyen, L. Nguyen-Son

A numerical procedure using a stable cell-based smoothed finite element method (CS-FEM) is presented for estimation of stability of a square tunnel in the soil where the shear strength increases linearly with depth. The kinematically admissible displacement fields are approximated by uniform quadrilateral elements in conjunction with the strain smoothing technique, eliminating volumetric locking issues and the singularity associated with the Mohr–Coulomb model. First, a rich set of simulations was performed to compute the static stability of a square tunnel with different geometries and soil conditions. The presented results are in excellent agreement with the upper and lower bound solutions using the standard finite element method (FEM). The stability charts and tables are given for practical use in the tunnel design, along with a newly proposed formulation for predicting the undrained stability of a single square tunnel. Second, the seismic stability number was computed using the present numerical approach. Numerical results reveal that the seismic stability number reduces with an increasing value of the horizontal seismic acceleration (αh), for both cases of the weightless soil and the soil with unit weight. Third, the link between the static and seismic stability numbers is described using corrective factors that represent reductions in the tunnel stability due to seismic loadings. It is shown from the numerical results that the corrective factor becomes larger as the unit weight of soil mass increases; however, the degree of the reduction in seismic stability number tends to reduce for the case of the homogeneous soil. Furthermore, this advanced numerical procedure is straightforward to extend to three-dimensional (3D) limit analysis and is readily applicable for the calculation of the stability of tunnels in highly anisotropic and heterogeneous soils which are often encountered in practice.