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

Hong Yin, Zehui Gao, Yulong Shao et al.

Joint deformation is a key factor controlling the mechanical behavior of discontinuous rock strata under changing stress conditions, including dominating the elastic deformation in near-surface excavations and serving as a major component of settlement under higher stress. This study, focusing on joint deformation behavior, investigates the effect of joint roughness on the peak stress and failure modes of specimens under uniaxial compression. Rock-like specimens with two layers of parallel, nonpersistent joints, one rough, were fabricated using 3D printing technology. Digital image correlation was used to capture real-time surface displacement fields, and a joint deformation analysis method was developed. The results show that joints exhibit staged, non-uniform closure and slip behavior, influenced by joint roughness, distribution of primary and secondary joints, and layered arrangement. Rough joints accelerate closure but hinder slip coordination, resulting in a three-stage loading process. In stage I, primary closure and layer-coordinated slip occur, accompanied by crack initiation, joint coalescence, and steady stress growth. Stage II involves secondary closure and overall coordinated slip, leading to localized failure and stress stabilization. Stage III is characterized by complete closure, uncoordinated slip, intensified crack propagation, and specimen failure, accompanied by stress hardening. The study reveals that joint deformation serves as a bridge linking roughness and peak strength. The average joint closure level and slip coordination are linearly negatively correlated with roughness but nonlinearly positively correlated with peak strength. Roughness restricts slip coordination, limiting crack propagation and delaying failure, which slows stress growth. Redistribution of joint aperture during slip reduces joint closure, weakens wall contact, and diminishes stress hardening.

W. Liao, Tian Wu, Shijie Zhang et al.

Faults are weak areas in rocks; however, faults have a very important impact on the construction and operation of underground gas storage. When gas is injected or produced into the gas storage, the increase or decrease in pore pressure in the surrounding rock mass may cause fault slip. A three-dimensional geomechanics model is established to study the evaluation methods and indicators of fault slip activation under alternating working conditions of gas storage. To accurately evaluate the stability of faults under alternating stresses and quantify their bearing capacity, this study established a three-dimensional dynamic rock mechanics model based on a fine three-dimensional geological model, combining one-dimensional rock mechanics modeling data and reservoir simulation results. This model uses a reservoir simulator and a rock mechanics simulator to calculate in synergy to reflect how the periodic pressure fluctuations inside the formation affect the local underground stress field and cause elastic and plastic deformation of the formation rock. Then, based on the relevant rock mechanics principles, the stability of the fault within the designed operating range can be quantitatively evaluated to optimize the operating pressure range of the gas storage in the best way. Set the fault to be open or closed for numerical simulation, observe the changes in the pressure monitoring curve of the monitoring well near the fault, and compare the observed curve with the pressure curve of the injection and production operation cycle to determine the closure of the fault. The calculation results show that one of the three faults is open. Drilling accidents are identified and analyzed to provide calibration data for formation stress and rock mechanics models, and a reliable three-dimensional geomechanics model is established. The grids through which the fault passes are marked as fault units, and their mechanical properties are obtained by distributing the equivalent rock mechanics parameters according to the different weights of the fault and the intact rock, and quantitatively describe the shear force, normal stress, pore pressure and friction coefficient acting on the fault plane. Based on the analysis of the maximum pressure rise in the geomechanics state and weak faults, the minimum limit formation pressure of the three faults is 42.5 MPa. Based on the analysis results of the gas storage fault, the ultimate bearing pressure of the gas storage is about 42MPa. Safety is always the top priority for gas storage. In addition to deploying monitoring wells, numerical simulation and rock mechanics research were also conducted to determine the evaluation method and calculate the safety index parameters for the safe operation of gas storage during the alternation of injection and production conditions, setting a benchmark and example for the operation of similar gas storages in this oilfield.

Karina Kohl, Luigi Carro

Software Engineering (SE) faces simultaneous pressure from AI automation (reducing code production costs) and hardware-energy constraints (amplifying failure costs). We position that SE must redefine itself around human discernment-intent articulation, architectural control, and verification-rather than code construction. This shift introduces accountability collapse as a central risk and requires fundamental changes to research priorities, educational curricula, and industrial practices. We argue that Software Engineering, as traditionally defined around code construction and process management, is no longer sufficient. Instead, the discipline must be redefined around intent articulation, architectural control, and systematic verification. This redefinition shifts Software Engineering from a production-oriented field to one centered on human judgment under automation, with profound implications for research, practice, and education.

Xiusong Shi, Xinbo Miao, Hao Xiong et al.

Bimsoils, consist of fine soil matrix and coarse rock aggregates, and are widespread as sedimentary soils. The bearing behavior of bimsoils are significantly affected by rock fraction. However, the mechanism governing the coarse fraction effect remains unclear. The traditional analysis methods are not effective in describing the rock fraction effect due to heterogeneous structure. To this end, 91 simulations have been performed to investigate the bearing capacity of bimsoils (mainly of two-dimensional, 2D) under shallow foundations using finite element method (FEM). It is found that the densified matrix bridge as well as the coarse aggregates forms a strong contact network which is responsible for the coarse fraction effect. A structure variable is introduced to quantify the reinforcing effect of rock aggregates. Then, a model incorporating the structural variable is proposed to evaluate the coarse fraction effect on the bearing capacity of bimsoils. Compared with the conventional method for pure soil matrix, only two additional parameters are required, and they can be readily calibrated by laboratory tests. The model is further validated by data available in literature, which can effectively estimate the bearing capacity of bimsoils under shallow foundations with a various of rock contents and rock characteristics.

Rui Jia, Zhenxing Chu

The triaxial mechanical properties and microscopic mechanisms of fly ash-based geopolymer-stabilized Tianjin clays with different fly ash (FA) contents, alkaline activator (AA) contents, curing times and confining pressures were investigated via triaxial and scanning electron microscopy (SEM) tests. Based on the triaxial test results, compared with the unstabilized clay, the stabilized clay exhibited a steeper stress–strain curve, a greater peak strength and pronounced strain softening behavior. A significant increase in cohesion (from 4.18 kPa to 64.5 kPa) and a slight reduction in the internal friction angle (from 30.3° to 28.6°) occurred after geopolymer stabilization. The stiffness, peak strength and residual strength of stabilized clay generally increased with increasing FA content, AA content, curing time and confining pressure. An FA/clay ratio greater than 0.1 and an AA/FA ratio greater than 0.6 were needed to achieve high strength at ambient temperature. The stabilized clay exhibited a significant strength improvement after 28 d and had a relatively high long-term strength. SEM results revealed that the chemical reactions between FA and AA led to the formation of sodium aluminosilicate hydrate (N-A-S-H) gel, which strengthened the bonds, filled the voids and reduced the porosity of the clay. As a result, the overall stiffness and strength of the stabilized clay improved. SEM analysis revealed that with a higher FA/clay ratio, a higher AA/FA ratio or a longer curing time, the geopolymerization process was more pronounced, leading to increased formation of the N-A-S-H gel and resulting in a more densely stacked and stronger bonded structure.

YANG Lei 1, MI Xiangyun 2, LI Zhaofeng 1, TU Wenfeng 2, XIE Yunpeng 2, HU Hao 1, WANG Kang 3

Aiming at the problems of strong disasters caused by water-rich dense weak surrounding rock and weak applicability of the conventional grouting materials, a new type of high-strength acrylic acid grouting material is developed, its polymerization reaction mechanism and working performance are analyzed, and the permeability and reinforcement characteristics of the new material on dense pulverized silty rock are studied. Based on the organic-inorganic interpenetrating network method, the high-strength acrylic acid grouting material is developed, which is composed of the main agent, inorganic modifier, initiator, accelerator, crosslinking agent and other raw materials, and it has remarkable characteristics of high strength and high permeability. The polymerization reaction of the two components of the high strength acrylate material is sufficient after mixing, and the inorganic network structure is evenly interspersed in the acrylate organogels network. According to the orthogonal tests, the characteristics of the new materials with different compositions, such as the gelling time, compressive strength and water absorption expansion rate as well as the influence rules of the components, are obtained. The gelling time range of the slurry is 45~201 s, the uniaxial compressive strength of the gel is 1.2~2.1 MPa, and the water absorption expansion rate is 16%~51%. The sensitivity ranking of factors affecting the main working properties of the new materials is further clarified. In accordance with the laboratory tests and microanalytical analysis technology, the permeability and reinforcement characteristics of grout in dense crushed rock are studied. The results show that the permeability and diffusion capacity of the high-strength acrylate grout is close to that of the pure one, which is much higher than that of the cement grout. Moreover, the high-strength acrylate material has an obvious coating and strengthening effect on crushed rock particles, and the solid strength reache 2.31 MPa. It is 5.4 ~ 11.0 times the reinforcement strength of the pure acrylic salt material, which can provide a strong safety guarantee for disaster grouting control and safe excavation of tunnels.

YANG Hongmin, LIU Qinquan, LI Pengyu et al.

After a mine fire or gas explosion, accurate detection of methane concentration is critical for disaster relief decisions. However, high-concentration CO2 from fires causes measurement deviations in optical interference methane detectors, as the CO2 absorption capacity of soda lime absorbent degrades over time. To investigate factors affecting detection accuracy in underground coal mine disaster areas, a simulation system was built to test soda lime's CO2 absorption under varied conditions. This revealed its time-dependent performance characteristics, failure mechanism, and enabled the establishment of a methane concentration correction model for CO2-rich atmospheres. The results show that soda lime's effective CO2 absorption cycles are negatively correlated with CO2 concentration. With CO2 concentrations of 5 %, 10 %, 15 %, 20.99 %, 27.18 %, and 32.09 % in the gas mixture, the effective absorption cycles are 20, 18, 12, 8, 5, and 3 times, respectively. The CO2 absorption time-efficiency curves exhibit an "S"-shaped nonlinear pattern under different concentrations and flow rates. Higher CO2 concentrations and gas flow rates increase absorption per unit time, shorten the high-efficiency duration, accelerate saturation/failure, and reduce the effective absorption time. Therefore, adjusting soda lime dosage and optimizing sampling flow rates are key to improving detection accuracy in high-CO2 environments.

Muhammad Shehryar, Arshad Raza, Guenther Glatz et al.

Carbon dioxide (CO2) storage in geological reservoirs faces viscous fingering, gravity override, and poor mobility control due to its low viscosity and resulting inefficient distribution and compromised storage capacity. Therefore, an urgent need arises to thicken the CO2 and enhance its viscosity for better mobility control and uniform distribution across the reservoir. This study examines the different schemes to enhance sweep efficiency in subsurface storage. In the context of polymer-, surfactant-, and foam-based technologies, the study defines optimization for CO2 injection and retention. Sweep efficiency is critical in maximizing reservoir usage and minimizing the risk of leakage by ensuring even dispersion of CO2. Polymers could increase CO2 viscosity, thereby yielding better mobility control and wider reservoir coverage. Surfactants reduce interfacial tension, enabling CO2 to invade less permeable areas, while foams act as conformance control agents, changing the flow path of CO2 away from the high permeability and into the underused areas. The study further includes advanced materials like CO2-soluble polymers, fluorinated surfactants, and nanoparticle-stabilized foams with superior stability under high-pressure, high-temperature conditions typical of deep reservoirs. Though effective, these approaches are challenged with chemical degradation, economic feasibility and environmental consequences. The study delves into these limitations and suggests integrated approaches involving polymers, and surfactant foams for enhanced sweep efficiency. These findings are a step towards realizing surfactant efficient and sustainable carbon sequestration technologies and contribute to the efforts of the world to mitigate climate change.

T. Ewumi, F. Ogunlana, A. Oyedele

Subsoil investigation constitutes a critical step in the planning and execution of any construction project. It is a prerequisite for the design and construction of safe, stable, and sustainable structures. Subsoil investigation using Electrical Resistivity Tomography (ERT) was carried out in Ado-Ekiti, Nigeria to assess the integrity of foundation soils/near-subsurface geomaterials. The study area is underlain by the crystalline basement terrain of southwestern Nigeria. The study delineated low resistivity zones having as low as 63 Ωm at a depth of about 10 m, localized pockets of clay intercalated by lateritic soil, a stretch of geomaterials of high resistivity values over 10000 Ωm observed at a depth of 6 m, and a structural feature diagnostic of fractured zone with intense weathering at depths stretching beyond 25 m. The presence of an underground water channel within the fractured basement rock is significant. The geological variations along the traverses confirm the heterogeneity of the basement complex rocks, even over short distances. This is crucial for foundation design. A gross assumption of uniformity could be hazardous to the stability of the structure. Geophysics remains a very fundamental tool that can be applied in civil engineering work. Use of integrated geophysical methods would reduce ambiguities and enhance site characterization for construction purposes.

Shisheng Chen, Nyuk Hien Wong, Chao Cen et al.

This study identified the key design factors related to thermal comfort in naturally ventilated underground spaces under high temperature conditions (outdoor Tmax = 42.9 C) in Fuzhou, China. Fuzhou has a humid subtropical climate and is one of the three hottest cities in China in 2024. Daytime measurements indicated reduced air temperature (AT), mean radiant temperature (MRT), and wind speed (V), together with elevated relative humidity (RH) in the underground space. Physiological Equivalent Temperature (PET) in the underground was consistently lower during peak hours (08:00-16:00), with the maximum difference in PET between pedestrian and underground levels being 11-11.9 C. Higher pedestrian-level PET at L1 was attributed to reduced greenery and shading, and decrement factors indicated greater thermal dampening at L2 (0.197) than at L1 (0.308). Sensitivity analysis showed that MRT was the most influential factor (S1/ST = 0.59-0.72) for aboveground spaces, followed by AT (0.13-0.26). In contrast, underground PET was mainly affected by metabolic rate (MET) (0.63-0.65), followed by RH (0.14-0.20) and V (0.08-0.18). Partial dependence analysis revealed that a 1 met increase in MET raised PET by 1.6 C, whereas a 1 m/s increase in V reduced PET by 1.5-2.2 C in the underground space. Due to cooler and more stable thermal conditions, underground spaces have higher tolerance for intensive physical activities. By buffering fluctuations in AT and MRT, underground environments can significantly alleviate heat stress and provide passive cooling shelter during daytime heat waves. Overall, this study provides empirical evidence to support underground space design in hot-humid climates and offers insights for sustainable urban heat mitigation.

Ali Aminzadeh, Prasanna Salasiya, Joseph F. Labuz et al.

Mineral carbon storage in rock formations has gained significant interest in recent years. In principle, changes in mechanical rock properties driven by carbon mineralization could be quantified using seismic methods, opening the door toward field monitoring of (the progress of) carbon storage. However, these changes may vary spatially within a rock mass when reactive transport occurs. In this vein, full-field ultrasonic characterization of reacted specimens can help shed light on the process. We use a 3D Scanning Laser Doppler Vibrometer to perform full-field monitoring of one-dimensional (1D) ultrasonic waves in rod-shaped sandstone specimens exposed to NaCl-rich fluid. Our initial experiments were conducted on intact sandstone specimens with high aspect ratio (length/diameter $\simeq 15$) to cater for 1D axial wave propagation. To investigate the evolution of the Young's modulus and attenuation of rock due to reactive transport, we exposed the specimens to an under-saturated NaCl solution, achieving supersaturation -- and so mineralization -- through evaporation. The upward movement of the fluid, supplied at the bottom of each specimen, was achieved through capillary action. We deploy an elastography-type approach to back-analysis, known as modified-error-in-constitutive-relation (MECR) approach, to expose the spatially-heterogeneous evolution of mechanical rock properties due to reactive transport. Our results consistently demonstrate (i) degradation of the Young's modulus, and (ii) increase in attenuation due to mineralization. To better understand the root causes of these changes, we made use of the X-ray micro-computed tomography ($μ$CT) and scanning electron microscopy (SEM) of selected cross-sections. The grain-scale information suggests that microcracking (resp. pore filling) is predominantly (resp. partly) responsible for the observed macroscopic changes.

P. K. Gautam, Marte Gutierrez

This paper studied the acoustic emission (AE) characteristics to show that there is a connection between AE dominant frequency information and crack propagation patterns in identifying synthetic rock specimens during loading, like when new cracks start to form or when existing cracks propagate. The study examined how brittleness influenced acoustic emission (AE) properties, including cumulative AE energy, average frequency (AF), and rise time to peak amplitude (RA). The results show the ratio of macrocracks to microcracks formed during rock failure. Rock brittleness impacts the AF value, but not the RA value. The more brittle the rock is, the higher the proportion of tensile cracks in the fracture process. The brittleness of synthetic rocks appeared to have an apparent effect on the AF value, but it did not significantly affect the RA value. The main frequency ranges for AF values in mix A1, mix A2, mix B1, and mix B2 samples were 219–3231 kHz, 206-330 kHz, 258–327 kHz, and 236-350 kHz, respectively. Analysis of the dominant frequency revealed that mix A2 and mix B2 are more distinct and useful for estimating the brittleness of the highly brittle rock compared to mix A1 and mix B1. The research results could further enrich the evaluation of rock brittleness and contribute to the deformation and failure to understand rock damage better. In recent years, the social economy has rapidly expanded, leading to a notable rise in the development of transportation and hydraulic tunnels, underground natural resource exploration, urban underground space utilization, and other underground excavation projects (Huang et al., 2021; Li et al., 2021; Gao et al., 2020). Excavation operations damage the rock mass, leading to significant alterations in stress distribution because of the mass's intricate structure, including faults, joints, defects, heterogeneity, and other preexisting natural discontinuities. This leads to the release of internal stress fields and stress concentration, which causes fractures to develop, advance, and expand inside the rock mass (Xu et al., 2021; Zhang et al., 2012; Li et al., 2017). Moreover, the overall load-bearing capacity of the rock mass diminishes, resulting in geological catastrophes, including subterranean building collapses, substantial deformation of adjacent rock, and sudden rock bursts. These factors significantly influence the design and operation of subterranean construction and excavation. Therefore, understanding rock deformation and its failure characteristics is crucial in the domains of rock mechanics and rock engineering. Stress-induced brittle fracturing weakens rock mass strength in man-made structures, which is significant for both theoretical and site investigation purposes (Wang et al., 2019; Lin et al., 2020; Wang et al., 2014; Mondal et al., 2019; Zhang et al., 2016; Wang et al., 2018; Lee and Jeon, 2011). Several researchers have found that when brittle rocks are compressed and found several stages of failure: failure and post-peak deformation, crack closure, linear elastic deformation, crack initiation, crack damage, and crack coalescence (Bieniawski, 1967; Wawersik and Fairhurst, 1970; Zhao et al., 2015). The stresses observed at different phases-crack closure stress, crack initiation stress, crack damage stress, and peak stress—are critical stress thresholds that influence the deformation and failure of brittle rocks under compression. Internal fissures in the rock release strain energy as transient elastic waves, leading to acoustic emission (Lockner, 1993; Turcotte et al., 2003; Wang et al., 2021; Sun et al., 2021). There is a significant link between the development of internal damage in rocks and acoustic emissions (AE). This relationship forms the foundation for using AE technology in rock mechanics and rock engineering (Stierle et al., 2016; Meng et al., 2018). Several studies have found at how rocks react to acoustic emission by using different types of compression tests, like tension, splitting, three-point bending, and uniaxial (Wang et al., 2022). Feng et al. (2019) used in-situ acoustic emission (AE) to observe cracks in rocks within the mining and geotechnical discipline. Thus, in this work, we chose acoustic emission (AE) technology to observe the progressive development of damage in rocks. The AE hit, which detects and quantifies an AE signal on a specific channel, is called the AE hit (PAC 2014). The quantity of AE hits detected by AE sensors is directly related to the number of microfractures formed inside the rock, as stated by Eberhardt et al. (1999) and Backers et al. (2005). AE parametric analysis, a standard indicator used to study rock deformation and failure processes, is determined by integrating the rectified waveform during the AE hits. Researchers frequently use AE parameters such as amplitude, counts, rise-time, duration, and AE energy to study rock failure mechanisms, measuring it by integrating the rectified waveform over the duration of the AE event (Chang and Lee 2004; Wang and Ge 2008; Meng et al. 2015). The AE energy magnitude can describe the scale and magnitude of a rock fracturing event (Hetenyi, 1996; Meng et al., 2015). The AE b-value has become known as a precursor indicator in rock engineering disasters, as a decrease in this value precedes the rock's ultimate failure (Colombo et al., 2003; Kurz et al., 2006; Meng et al., 2016; Meng et al., 2019; Liu et al., 2020; Dong et al., 2021). As a result, this technique is difficult to use in engineering practice and laboratory research because it requires more than six AE sensors. Using statistical analysis to identify dominant frequencies in AE is a new way of studying synthetic rock failure processes, as well as the micro- and macro-failure processes of synthetic rocks. There is a notable lack of observations on the relationship between the dominant AE frequency characteristics and the real-time cracking process of synthetic rock. Zhang et al. (2023) used the AE technique to investigate the macro-scale failure pattern and variations in sandstone's mechanical characteristics. It compacted the sandstone with varying levels of moisture content. Researchers observed that the AE spectrum exhibits four distinct responses during sandstone fracture. There are different types of signals that show cracks in minerals and crystals. Low-frequency low amplitude (LF-LA) signals show cracks that move between or within minerals or crystal particles; intermediate frequency low amplitude (IF-LA) signals show friction in microcracks; high frequency low amplitude (HF-LA) signals show fracture in microcracks; and low frequency high amplitude (LF-HA) signals show large-scale cracks. Therefore, the aim of this study is to examine how the main frequency and amplitude of acoustic emission (AE) waveforms change in real time as synthetic rocks undergo uniform compression, with a focus on how cracks form in the rocks. This study utilizes acoustic emission methods to investigate the brittle characteristics of a synthetic rock.

Yian Chen, Shujie Zhao, Jiang Xu et al.

In the construction of underground geological engineering, a variety of rocks were often encountered, and the engineering surrounding rocks was prone to shear fracturing. Shear mechanics tests were conducted on a variety of rocks under various joint angles. By studying the shear mechanical characteristics, acoustic emission behavior, and damage degree of the different rock types, we can obtain an insight into their bearing capacity and fracture mechanisms. An obvious inflection point from the elastic to plastic behavior can be observed for the specimens during the process of shear mechanics tests, and the shear behavior was divided into three phases. The acoustic emission signals significantly increased for coal during the second phase, while those of sandstone and shale start to increase during the third phase, which is from the peak point to fracture. The analyses of the shear failure and acoustic emission properties showed that the crack propagation angle increases as the normal stress of rock increases. It was proved that the joint angles and normal stresses of rock could effectively hinder the development of vertical fractures. Based on the shear failure and acoustic emission properties, a constitutive model capable of describing the shear behavior of different types of rocks was developed. This constitutive model can accurately describe the shear fracture properties of the various rocks. The shear failure properties and damage constitutive model of rocks in this study can be used to reduce engineering surrounding rock instability caused by shear.

Long-Chuan Deng, Yi-Xiang Yuan, Xiao-Zhao Li et al.

It is inevitable to cut reinforced concrete (RC) appeared in cross passage of city metro by cutting tools when constructing in densely populated area. The previous cutters employed to cut RC are insufficient and easily damaged, so a new polycrystalline diamond compact (PDC) cutter is used to solve this question. Based on the theoretical analysis of cutting mechanism, both circular and tapered PDC cutters with cutting edge angle of 90° and negative front rack angle of 10° are used to cut RC. The peeling and breaking patterns of cutting concrete are proposed, the nodular and grainy chips are the preferred modes in cutting steel bars. The LS-DYNA is employed to investigate the cutting performance in advance. The simulation results show that the average and peak cutting forces increase with the growth of penetration depth, cutting speed, and roundness, and subsequently the recommended penetration depth less than 1.2 mm is obtained to cut RC due to the existence of steel bars. Moreover, the linear cutting platform is adopted to investigate the force ability and damage state of PDC cutters. It is concluded that the cutting force increases abruptly and fluctuates heavily when cutting the coarse aggregates. The patterns occurred in both numerical and experimental results are generally similar. Notably, the steel bar is pulled out and the PDC cutter is damaged at the penetration depth of 0.8 mm, while a good cut occurs at the penetration depth of 0.3 mm. The tapered PDC cutter with a relatively low cutting force is prone to be broken compared with circular PDC cutter. It is suggested that the circular PDC cutter at the penetration depth of 0.3 mm should be used to cut RC in practical engineering.

QIAO Liping 1, WANG Fei 1, WANG Zhechao 2, LI Cheng 2

The additional vertical water curtain system is required in the underground water-sealed oil storage cavern project in coastal areas to meet its water-sealed properties and control seawater intrusion. In order to study the design method and parameters for the vertical water curtain system, the influence laws of four parameters of hole distance from the storage cavern (d), hole spacing (b), hole length (l) and hole injection pressure () of the vertical water curtain on the groundwater seepage field, water-sealed properties, water inflow and seawater distribution range around the cavern are obtained by using the finite element numerical simulation method and compared with the existing results for verification based on an underground water-sealed oil storage cavern in the coastal area. The research shows that the hole distance of the vertical water curtain from the storage cavern mainly has an impact on its burial depth range. The range of influences of the length depends on the location of the change beyond the storage cavern, and the spacing and injection pressure affect the entire depth range. The degree of influences of the four parameters on the water-sealed properties and prevention of seawater intrusion are as follows: b<l<d< and d<b<l< , respectively. A total of seven cases in the study are at risk of seawater intrusion into the cavern, and further enhancement of freshwater recharge is required. The research results can provide a theoretical basis for the design parameters of the vertical water curtains of the groundwater-sealed oil cave reservoirs in coastal areas.

C.E. Obi, A.R. Hasan, M.A. Rahman et al.

This review addresses the diverse applications of multiphase flows, focusing on drilling, completions, and injection activities in the oil and gas industry. Identifying contemporary challenges and suggesting future research directions, it comprehensively reviews evolving applications in these multidisciplinary topics. In drilling, challenges such as gas kicks, cutting transport, and hole cleaning are explored. The application of immersion cooling technology in surface facilities for gas fields utilized in integrated bitcoin mining is also discussed. Nanotechnology, particularly the use of nanoparticles and nanofluids, shows promise in mitigating particulate flow issues and controlling macroscopic fluid behavior. Nanofluids find applications in drilling for formation strengthening and mitigating formation damage in completions as highlighted in this work, as well as in subsurface injection for enhanced oil recovery (EOR), waterflooding, reservoir mapping, and sequestration tracking. The review emphasizes the need for techno-economic analyses using multiphase flow models, particularly in scenarios involving fluid injection for energy storage. Addressing these multiphase flow challenges is crucial for the future of energy diversity and transition initiatives, offering benefits such as financial stability, resilience, sustainability, and reliable supply chains. The first part of this review presents the application of multiphase (typical gas, liquid, solid) flow models and technology for drilling, completion, and injection operations. While the second part reviews the applications of multiphase particulate (nanofluid) flow technology, the use of computational fluid dynamics (CFD), machine learning (ML), and system modeling for multiphase flow models in drilling, completions, and injection operations.

Rahul Deshpande, Ricardo Vinuesa

The present study investigates streamwise ($\overline{u^2}$) energy-transfer mechanisms in the inner and outer regions of turbulent boundary layers (TBLs). Particular focus is placed on the $\overline{u^2}$-production, its inter-component and wall-normal transport as well as dissipation, all of which become statistically significant in the outer region with increasing friction Reynolds number ($Re_τ$). These properties are analyzed using published data sets of zero, weak and moderately strong adverse-pressure-gradient (APG) TBLs across a decade of $Re_τ$, revealing similarity in energy-transfer pathways for all these TBLs. It is found that both the inner and outer peaks of $\overline{u^2}$ are always associated with local maxima in the $\overline{u^2}$-production and its inter-component transport, and the regions below/above each of these peaks are always dominated by wall-ward/away-from-wall transport of $\overline{u^2}$, thereby classifying the $\overline{u^2}$-profiles into four distinct regimes. This classification reveals existence of phenomenologically similar energy-transfer mechanisms in the `inner' and `outer' regions of moderately strong APG TBLs, which meet at an intermediate location coinciding with the minimum in $\overline{u^2}$ profiles. Given that the wall-ward/away-from-wall transport of $\overline{u^2}$ is governed by the $\rm Q_4$(sweeps)/$\rm Q_2$(ejections) quadrants of the Reynolds shear stress, it is argued that the emergence of the $\overline{u^2}$ outer peak corresponds with the statistical dominance of $\rm Q_4$ events in the outer region. Besides unravelling the dynamical significance of $\rm Q_2$ and $\rm Q_4$ events in the outer region of turbulent boundary layers, the present analysis also proposes new phenomenological arguments for testing on canonical wall-turbulence data at very high $Re_τ$.

S. L. Gavrilyuk, H. Gouin

By dispersive models of fluid mechanics we are referring to the Euler-Lagrange equations for the constrained Hamilton action functional where the internal energy depends on high order derivatives of unknowns. The mass conservation law is considered as a constraint. The corresponding Euler-Lagrange equations include, in particular, the van der Waals--Korteweg model of capillary fluids, the model of fluids containing small gas bubbles and the model describing long free-surface gravity waves. We obtain new conservation laws generalizing the helicity conservation for classical barotropic fluids.

Jonas Heinzmann, Pietro Carrara, Chenyi Luo et al.

In the context of the Damage Mechanics Challenge, we adopt a phase-field model of brittle fracture to blindly predict the behavior up to failure of a notched three-point-bending specimen loaded under mixed-mode conditions. The beam is additively manufactured using a geo-architected gypsum based on the combination of bassanite and a water-based binder. The calibration of the material parameters involved in the model is based on a set of available independent experimental tests and on a two-stage procedure. In the first stage an estimate of most of the elastic parameters is obtained, whereas the remaining parameters are optimized in the second stage so as to minimize the discrepancy between the numerical predictions and a set of experimental results on notched three-point-bending beams. The good agreement between numerical predictions and experimental results in terms of load-displacement curves and crack paths demonstrates the predictive ability of the model and the reliability of the calibration procedure.

Wengang Zhang, Kok-Kwang Phoon