bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting Excavation Performance of EPB TBM by Using Soil Properties: A Case Study of Dudullu Bostanci Metro Project
Authors: Seyedrezaei M. , Tumac D. 
Published: August 2024

ABSTRACT:
This study was conducted to determine the effects of soil properties on the excavation performance of an earth pressure balance tunnel boring machine (EPB TBM) used in the Istanbul Dudullu-Bostanci Tunnel Project. Soil samples were collected from different locations along the tunnel route, and subjected to laboratory tests to determine the particle size distribution, natural water content, consistency limits (liquid limit, plastic limit, plasticity index, and consistency index), fall cone penetration depth, unified soil classification, and clogging potential. The field performance data were obtained from the EPB TBM data logger. Data analysis was carried out by statistically linking the TBM thrust force, and instantaneous cutting rate, with the geotechnical properties of the excavated soil by using single and linear regression methods. The results indicate that the fall cone penetration depth can be used for predicting the thrust force, the plastic limit for the instantaneous cutting rate, and the plastic limit and plasticity index, as well as the consistency index, for field-specific energy predictions. Additional studies are required to provide more reliable and generalized prediction models, by increasing the number of laboratory and field tests for different soil types and performance data for different EPB TBMs.

1. INTRODUCTION
The escalating growth of the urban population has necessitated the development of new infrastructural systems, including metro and water tunnels, along with utility networks. The challenge of optimizing the limited space available, coupled with the need for an infrastructure of higher quality, compels policymakers to consider the more extensive utilization of underground spaces. This scenario requires engineers to devise innovative solutions to tackle the construction challenges encountered in densely populated areas.
The efficacy of management is often subject to examination due to the contractual conflicts that arise in the construction phase. Frequently, the roots of these problems can be identified in the early planning stages. Expectations that are not grounded in realism regarding performance can significantly hinder a contractor's capacity to oversee construction projects with efficiency. Predicting the excavation rate is paramount in the planning of TBM (Tunnel Boring Machine) excavation.
The excavation process typically represents the critical path for tunnel projects, with the project's cost and schedule heavily reliant on the TBM performing as anticipated.
Investigation of Failure Mode and Permeability Evolution of Inclined Heterolithic Strata Using Coupled Discrete Element Method-Computational Fluid Dynamics Model
Authors: Yin X. H. , Zhang B. 
Published: August 2024

ABSTRACT:
The presence of inclined heterolithic stratification (IHS) poses significant challenges in operational efficiency for in-situ recovery of oil sands as low-permeability IHS will hinder the vertical propagation of steam chamber. The potential shear failure and slip along IHS may lead to severe instability issues for pit slopes. Coupled Discrete Element Method (DEM)-Computational Fluid Dynamics (CFD) model is constructed to match the flow and geomechanical response of reconstituted IHS specimen and extended to investigate the mechanical behavior, permeability evolution, and failure mode of IHS specimens considering the variation of mud content (0-100%). A novel permeability equation based on porosity variation and crack numbers is established to quantify the permeability change due to macroscopic deformation and failure from a microscopic perspective. This study establishes a quantitative relationship between the geological characteristics and coupled flow-geomechanical behavior of IHS, which is crucial for operational optimization and safe management of in-situ recovery and open-pit mining of oil sands. The developed model is also a useful instrument enabling quantification of mechanical constitutive behavior and permeability evolutions for rock and soil with interbedded weak beddings.

1. INTRODUCTION
The subsurface heterogeneities formed during geological deposition and diagenesis is outstanding challenges in accurate and reliable geotechnical assessment and have attracted increasing attention in subsurface energy geotechnics (Fang & Harrison, 2002; Iferobia & Ahmad, 2020). Weak beddings are the most common types of lithological heterogeneity, which could be traces of fractures or sedimentary structures during the sedimentary processes. As a special form of weak beddings, the existence of IHS in the McMurray Formation of Alberta oil sands leads to pronounced declines in operational efficiency for in-situ recovery of oil sands since it hinders the vertical development of steam chamber (Martinius et al., 2017). A comprehensive investigation of the failure modes and permeability evolution of IHS under stress changes becomes imperative for enhancing recovery efficiency while ensuring the caprock integrity in the in-situ recovery of oil sands. This study aims to investigate the mechanical behavior, permeability evolution, and failure mode of IHS under stress and strain changes.
Investigation on the Spatial Variation in Fracture Orientation and its Impact on Hydraulic Behavior of Rock Mass
Authors: Choi J. , Kim J. , Song J.-J. 
Published: August 2024

ABSTRACT:
The consideration of spatial variation in fracture distribution within a rock mass is crucial for enhancing the reliability of Discrete Fracture Network (DFN) modeling because, in nature, fracture properties exhibit non-uniformly distributed characteristics. Few studies have explored the degree of spatial variation within rock masses and its relationship with hydraulic performance. This study investigates the spatial variation of fracture orientation using outcrop data collected from various regions. Twenty-one trace maps were divided into several sub-domains, and the spatial variation between them was analyzed using a correlation coefficient. We find that trace maps exhibit spatial variation in fracture orientation. The degree of variation significantly depends on the region from which the outcrop data originates. It is less influenced by the scale of outcrop maps or the quantity of fractures within the maps. Furthermore, hydraulic analysis was conducted for two trace maps exhibiting high and low spatial variation. The results reveal that high spatial variation leads to larger discrepancies in directional permeability. These findings emphasize the importance of considering spatial variation in fracture orientation when assessing hydraulic behavior in rock masses for application problems.

1. INTRODUCTION
Fracture networks are essential when evaluating the hydraulic behavior of rock masses since fluid flow mainly occurs through fractures rather than rock matrix (Min et al., 2004). Discrete Fracture Network (DFN) modeling, based on statistical characteristics derived from outcrop data, is commonly employed to investigate the permeability of rock masses (Davy et al., 2018).
Numerous studies have analyzed the hydraulic performance of rock masses using DFN (Min et al., 2004; Baghbanan and Jing, 2007; Youn and Gutierrez, 2011). Monte Carlo simulations have been utilized to assign fracture properties for generating DFN models, followed by permeability calculations for various model sizes. The concept of the equivalent discrete fracture network (E-DFN) has been also explored to propose a method for generating DFN with low computational cost (Ren et al., 2017; Ma et al., 2020).
Recently, the spatial distribution characteristics of fractures have emerged as an important consideration. Fracture distribution in real rock masses often exhibits spatial variation or spatial correlation due to factors such as deformation zones or changes in stress regimes (Selroos et al., 2022). These features should be taken into account when modeling DFN for sites that require high precision such as nuclear waste repositories, yet existing methods cannot reflect these characteristics.
Numerical Simulation of Damage Evolution and Fracture Propagation in Deep Shale by Liquid Nitrogen
Authors: Liu Xu , Liu Ying , Qu Hai , Zeng Zhijun , Lu Zhitian , Wang Shi , Liu Xiaodong 
Published: August 2024

ABSTRACT:
With abundant deep shale gas resources in China, the future increase in natural gas production is critical. Liquid nitrogen fracturing in deep shale formations can generate complex fractures, making it vital to understand the intricate coupling relationships among the mechanical, flow, and temperature fields within these reservoirs. This paper systematically investigates the mechanisms of damage and fracturing in deep shale under the low-temperature effects of liquid nitrogen, focusing on the characteristics of fracture expansion. Employing a thermo-hydro-mechanical coupling model, the study explores the influence of in-situ stress conditions, borehole length, and bedding angle on the damage evolution of the rock mass in the vicinity of the wellbore. By constructing realistic reservoir models, the research simulates the initiation and expansion of fractures in rock formations under the combined effects of high pressure and thermal stress. It examines the correlation between nitrogen injection duration, fracture density, reservoir temperature, and the laws governing crack initiation and propagation, unveiling the characteristics of fracture damage in deep shale under various parameters and their impact on the morphology of fracture expansion.

1. INTRODUCTION
In recent years, the depletion of conventional oil and gas reservoirs has prompted the oil and gas industry to pivot its focus towards unconventional reservoirs(Bentley, 2002; Kontorovich, Epov, & Eder, 2014). Among these, shale gas has emerged as the fastest-growing source, alongside coalbed methane, tight gas, and natural gas hydrates (Vidic, Brantley, Vandenbossche, Yoxtheimer, & Abad, 2013; Q. Wang, Chen, Jha, & Rogers, 2014). As a crucial element of unconventional oil and gas resources, shale gas has been instrumental in addressing the escalating global demand for fossil fuels.
Hydraulic fracturing, a widely utilized method for economically exploiting shale gas, facilitates the creation of artificial fractures with adequate permeability. Nevertheless, in recent years, traditional large-scale hydraulic fracturing has been increasingly scrutinized due to concerns such as water consumption, environmental pollution, and formation damage(Zou et al., 2017). Furthermore, the adverse impacts of geological variations on fracturing production have ultimately led to a significant reduction in the recovery rate of shale gas wells(Zhao et al., 2023).
Geotechnical Hazards in Deep Mines: Case Studies of Seismicity and Boundaries Changes
Authors: Masethe R. T. , Leite A. R. S. , Landry D. 
Published: August 2024

ABSTRACT:
Seismic events and rockbursts are recurrent geotechnical hazards in deep underground mines with significant levels of stress and extraction. These hazards can be manageable if adequately addressed during the design and monitoring phase. However, changes in the geological boundaries can trigger a series of seismic events. Temperature fluctuations and the presence of water can alter the stress conditions, mechanical properties of rock mass and affect geological discontinuities. Two case studies are presented. The first case study focuses on seismicity induced by an underground fire in a deep-level gold mine in South Africa. The second case study investigates seismic events caused by water from backfill pouring in a deep-level copper/nickel mine in Canada. An analysis of the source mechanisms of these induced seismic events revealed that they vary from burst-type to slip-type seismic events. The significant seismic activity during sand fill pouring in the Canadian mine confirmed the high stress predicted by the numerical model (Deviatory Stress Ratio &gt; 0.5). The stress and past seismic events influenced ground support selection for rock burst-prone areas.

1. INTRODUCTION
As mines deepen, geotechnical hazards become less forgiving, and companies must recognize that failing to identify and mitigate these in design and operational strategies could be catastrophic, resulting in significant mine underperformance or premature closure. The objective of these case studies, both in the gold and the copper/nickel mines, is to improve our understanding of the way the fluctuating temperature impacts the operations, and the presence of water can alter the stress conditions, mineralogy, and mechanical properties and affect the geological discontinuities in the deep mines.
The geotechnical hazard results in rockbursts, which are more common in deep, hard rock mines and represent one of the most severe mining hazards affecting the operation's safety, economics, and productivity. The violent and unpredictable nature of these rockbursts makes them remarkably challenging to mitigate and control. The two studies presented below include a case study on seismicity induced by an underground fire in a deep-level gold mine in South Africa. The other case study investigates seismic events caused by water from backfill pouring in a deep-level copper/nickel mine in Canada.
Statistical Analysis of Rock Cutting Forces Acquired from Full-Scale Linear Rock Cutting Machine Tests
Authors: Ishaq Muhammad , Thyagarajan Muthu Vinayak , Rostami Jamal 
Published: August 2024

ABSTRACT:
Understanding rock-cutting forces encountered in the field requires full-scale rock-cutting tests with original tools. The most reliable method that accounts for critical aspects of rock-cutting technologies is a full-scale linear cutting machine (LCM) test. The cutting force data acquired through this test sheds light on how the rock and cutter interact, as well as how different cutting geometries and tool variations perform in different geologic formations. Peaks in recorded forces during the full-scale cutting represent the points of a major failure of rock leading to chip formation. This study utilizes a statistical approach to conduct a thorough analysis of cutting force data collected during full-scale LCM testing. As an alternative to the calculation of average or peak cutting force values, the emphasis is on establishing a statistically derived range of forces to assess the cutting force data for performance prediction. The proposed methods and existing methods along with literature were used to model selected machines and compared with field data for validation.

1. INTRODUCTION
A full-scale linear cutting machine (LCM) test is the most reliable method for the evaluation of rock cutting parameters, as it uses large-scale rock samples that closely represent the rock mass character and force requirements in the field (Cho et al., 2013; Dogruoz et al., 2016; Rostami, 1997; Thyagarajan, 2018; Yasar & Yilmaz, 2018). While full-scale LCM tests provide the most realistic rock cutting data, real-world simulation techniques that cannot be combined with other testing methodologies, such as advanced numerical modeling, can be examined (Jeong et al., 2020). The emphasis on full-scale testing arises from the fact that rock is a heterogeneous media with micro/macrostructures, and its behavior is greatly affected by scale (Balci & Bilgin, 2007; Bilgin et al., 2006; Thuro & Plinninger, 2001). Thus, the full-scale LCM test remains the preferred methodology for understanding real-world rock cutting efficiency despite formidable logistical challenges (Balci & Bilgin, 2007; Bilgin et al., 2006; Pan et al., 2018; Rostami, 1997).
Confinement Effect on Operating Limits of TBM Based on a Theoretical Model for Rock Indentation
Authors: Yang Hongwei , Liu Wenjie 
Published: August 2024

ABSTRACT:
Mechanized tunneling using tunnel boring machine is mainly a thrust controlled process that can conveniently be modeled by indentation tests. Under confinement, the indentation force required to fragment rocks is significantly larger than that at ambient conditions, which necessitates consideration of lateral confinement in predicting penetration rate. Yet, most of the proposed methods for estimating penetration rate are of phenomenological nature, with only a few based on theoretical analysis for which it is not straightforward to extend to confinement conditions. In this study, we exploited the model recently developed for analyzing data of rock indentation tests with lateral confinement on specimens of variable sizes and extended it to predict penetration rate and thrust required to fragment rocks. The effect of confinement on indentation is accounted for by the increases in compressive strength with lateral confinement. In comparison to CSM model, the model predictions require three extra parameters: confinement, the simplified cavity shape that relates to the cutter shape and the ratio between damage zone size and cutter spacing. The three parameters can be obtained/calibrated by using experimental data obtained from laboratory-controlled linear cutting tests. The predicted operating limits using power of TBM head suggests that under confinement conditions the maximum feasible penetration rate that can be reached is reduced. The proposed method can serve as a start-point for estimating operating limits for TBM under confinement conditions.

1. INTRODUCTION
In mechanized tunneling using tunnel boring machine (TBM) the thrust and penetration rate that can be achieved, or operating limits, are of great interest for the planning and construction stages for a project. Tunneling normally takes place around tens to hundreds meter in depth, thus subjected to elevated in-situ stresses at a magnitude of up to tens of megapascals. Rock behavior at confinement conditions differs from that at ambient conditions according to conventional triaxial compression test results (e.g., Paterson & Wong, 2005), which is also reflected in in the significantly larger thrust required to fragment rocks in rock cutting/indentation tests (e.g., Wang et al., 2021; Wang et al., 2022; Yin et al., 2014). Therefore, predictions of the operating limits would need to include the expected strengthening effect of confinement on rock excavation.
Study on Numerical Simulation Method of Profile Control with Polymer Microspheres
Authors: Ma Mengqi , Li Junjian , Zhu Zhouyuan , Yuan Shuai , Yu Fuwei , Su Hang 
Published: August 2024

ABSTRACT:
As a novel method of profile control and enhanced oil recovery, polymer microspheres have been applied extensively in the oil industry. Based on the mechanism of microspheres, an equivalent numerical simulation method is established in the paper to predict its application performance. The method comprehensively considers the properties of microspheres such as expansion, retention, blockage, and degradation. And its accuracy is proven by matching the vital data of laboratory experiments. Then the sensitivity analysis of injection parameters is carried out to optimize simulation results. The reservoirs with different permeability values are selected as cases to predict and evaluate the application effect of the microspheres flooding. It is found that the simulated oil production is consistent with the field data, and there is a significant downward trend in water cut. This numerical simulation method of polymer microspheres is verified by both comparing with experimental data and matching field history, which can be used to guide the reservoir engineering schemes design for microspheres displacement.

1. INTRODUCTION
According to the exploration data of developed oil fields, the reservoirs that can be exploited with sufficient natural energy account for a low proportion of exploitable reservoirs. The waterflooding measure is applied in most oil fields to achieve the goals of maintaining stable production and gaining higher recovery. Nevertheless, because of the increased heterogeneity of the formation, there is still a large amount of crude oil that has not been produced after waterflooding. Therefore, how to relieve the heterogeneity becomes a significant problem for the effective development of such reservoirs (Xie et al, 2023; Wang et al, 2021).
In order to alleviate the above problems and better produce the residual oil in the formation, profile control measures should be adopted. The key to obtaining a great effect by profile control methods lies in selecting the adapted plugging agents. Currently, the commonly used plugging agents are divided into gel, particle, foam and microorganism (Sun et al, 2023; Wang et al, 2020). Among them, the polymer microspheres, which belong to particle-type plugging agents, have attracted wide attention and conducted relevant research because of their characteristics that "being capable of injection, blockage, and movement" (Wu et al, 2022).
Pressure and Stress Prediction Using Seismic Velocities, 3D Geomechanical Models and the Full Stress Tensor: Mad Dog Field, Deepwater GoM
Authors: Nikolinakou M. A. , Flemings P. B. , Heidari M. , Wang X. , Johri M. 
Published: August 2024

ABSTRACT:
We discuss a 3D case study for pressure and stress prediction in the Mad Dog field, deepwater GoM. We employ a novel approach that couples seismic velocities with geomechanical models and the full stress tensor (including lateral and deviatoric stresses; FES workflow). We show that steeply inclined salt faces increase the stress ratio in wall rocks. We further show that below salt overhangs, the stress state remains practically uniaxial. We discuss that the approach predicts stress perturbations that result from the 3D salt geometry and extend km away from salt. We extract pressure and stress along a well and show that the geomechanical prediction of least principal stress is systematically lower than the uniaxial estimate but comparable to field measurements. This is because the 3D model captures the extensional effect of the anticline structure in the area. Overall, we demonstrate that the 3D FES models incorporate the complexity of salt loading not captured by any VES approach and can provide pressure and stress estimates along any existing or planned well paths.

1. INTRODUCTION
Pre-drill pore pressure and stress prediction is crucial for borehole stability, planning of safe and economic well trajectories and design of casing plans (Dodson, 2004; Flemings, 2021; Zhang, 2013). It is also a key input in the exploration stage to determine the integrity of reservoir seals.
Pressure-prediction workflows are commonly based on the vertical effective stress (Zhang, 2013). Such workflows have been successfully established because, in sedimentary basins, strain is uniaxial and sedimentation drives loading and overpressure generation (Bowers, 1995; Osborne & Swarbrick, 1997).
In the vertical effective stress (VES) workflow, the vertical effective stress across the volume of interest in calculated by coupling the seismic velocity with a velocity – vertical effective stress relationship, for example that of Bowers (1995):
(equation)
where (equation) is the vertical effective stress, V is a velocity measurement (e.g., seismic or sonic), V0 the velocity of water, and A & B empirical coefficients calibrated using well measurements at a regional well (see Appendix A for nomenclature).
Pore pressure, uVES, is then estimated as the difference between the vertical total stress (σv) and vertical effective stress:
(equation)
The vertical total stress is usually assumed to be equal to the overburden stress.