bluuebunny/crossref_metadata_2025_split huggingface dataset:
Small-strain characterization of Shanghai clays by triaxial compression tests
Authors: Lan L , Ye G , Zhu W , Zhang Q 
Published: May 2024

Abstract
The mechanical properties of the upper Shanghai Layers 2-6 clays at small strain levels have been extensively investigated. Nonetheless, limited data exist on their small-strain characteristics through K
0-consolidated undrained triaxial compression tests, with even less information available for the deeper layers 8 and 10. This study employed a series of K
0-consolidated undrained TC tests on intact samples from both the upper layers 2-6 and the deeper layers 8 and 10 of Shanghai clay. We evaluated the undrained maximum secant stiffness (Eu

max) and reference shear strain (γ0.7
). An increase in over-consolidation ratio (OCR) results in a higher E
u
max/p’ and a more rapid decay of the G/G
max with the increasing shear strain (γ). As the value of γ
0.7 increases with I
p and decreases with OCR, a correlation between γ
0.7 and Ip
can be established. This study observed significant correlations between the E
u
max, effective stress (p’), and the maximum deviatoric stress, as well as between E
u
max and the cone resistance obtained from field cone penetration tests. These correlations offer methods to estimate E
u
max and γ0.7 values based on parameters that are more readily measurable, which provide critical references for the calculations and design parameters in foundation engineering within the Shanghai region.
Effect of geotechnical soil properties on CBR value: A review
Authors: Pule B B , Yendaw J A 
Published: May 2024

Abstract
This review paper presents the current research state of the relationship between geotechnical soil properties and the California bearing ratio (CBR) value. Geotechnical considerations are pivotal in civil engineering projects to prevent collapse and settlement failures, underscoring the importance of understanding detailed soil properties. A CBR test used for assessing stiffness modulus and shear strength guides the overlaying layer-thickness calculation during pavement design. Although expensive and complex, researchers have explored correlations and machine-learning algorithms for CBR prediction from soil properties. This study delves into the varying influence of properties such as compaction (optimum moisture content and maximum dry density) and index (liquid, plastic, and shrinkage limits) properties. The relevance of such properties to CBR is explored, examining their significance and potential interactions. This review highlights the multi-faceted effects of soil properties on CBRvalue, enabling informed pavement engineering decisions.
Novel apparatus for visualizing hydraulic fracturing in soils
Authors: Li Kun-peng , Chen Yong-gui 
Published: May 2024

Abstract
This paper presents a new apparatus designed specifically for visualizing hydraulic fracturing in soils. The apparatus comprises four main units: an injection cell, a visualization unit, a pressure/volume control unit, and a data acquisition unit. The injection cell is characterized by a transparent, high-transmittance polymethyl methacrylate top cover that enables direct visual observation. The visualization unit includes a visual studio and a high-resolution camera that captures macro-fracturing dynamics. The pressure/volume control unit enables specific test requirements to be satisfied during injection tests. The data acquisition unit records injection pressure and water volume data over time. To validate the performance of the novel apparatus, we conducted a systematic injection test on Gaomiaozi bentonite with a dry density of 1.3 g/cm3 and a water content of 9.39%. The results indicate that the apparatus accurately captures macro-fracturing dynamics and records injection pressure and water volume data in real-time.
Implementation of modified cam–clay model using closest point projection method under Cartesian coordinate system
Authors: Xie Zhongkai , Ren Gang , Xu Chao , Huang Zhiqiang 
Published: May 2024

Abstract
The modified Cam–Clay model is an elastoplastic soil model that holds a prominent position in civil engineering for its precise depiction of varied soil behaviors. Despite extensive examination of its numerical processes, the predominant focus on stress integration algorithms within the triaxial stress space presents challenges for individuals less acquainted with geotechnical science. In response to this, the present study derived the stress integration equations for the modified Cam–Clay model within the Cartesian coordinate system employing the closest point projection method. Subsequently, a finite element program was developed incorporating the derived integration process. This study computed and compared the consolidation processes under both drained and undrained conditions for cubic soil samples with various over-consolidation ratios using the developed program, ABAQUS, and analytical formulas. The findings demonstrate that equations integrated within the Cartesian coordinate system offer ease of understanding and programming. The feasibility, accuracy, and stability of the closest point projection method have been validated. Comparative analysis of soil samples across various over-consolidation ratios indicated a reduction in failure stress with an increase in over-consolidation ratio, indicating a higher propensity for failure under undrained conditions than under the drained conditions.
Coupled peridynamic modeling of hydraulic fracturing in rocks
Authors: Yang Changyi , Zhu Fan , Zhao Jidong 
Published: May 2024

Abstract
This paper presents a fully coupled peridynamics method for simulating hydraulic fracturing in rocks. The proposed method involves a rigorous coupling between the classical total-Lagrangian formulation and a new semi-Lagrangian formulation within the framework of peridynamics. The total-Lagrangian formulation is employed to simulate a rock subjected to fluid-driven fracturing, whereas the semi-Lagrangian formulation is used to solve the Navier–Stokes equations for fluids in a nonlocal manner. A coupling algorithm is developed between the two formulations to model fluid–solid interactions without causing unphysical penetration. The proposed method was validated through a simulation of a water column collapse problem. It was further validated using a Kristianovich–Geertsma–De Klerk (KGD) fracturing problem, where a plane strain fracture propagates owing to fluid injection. The proposed method reasonably captures the fracturing pattern, fracture propagation speed, and injection pressure better than the analytical solution. It offers a unified framework within the peridynamics theory for modeling solid, fluid, and fluid-driven fractures.
Anisotropic Breakage Mechanics for cemented granular materials
Authors: Shen Xianda , Buscarnera Giuseppe , Zhang Fengshou 
Published: May 2024

Abstract
The anisotropy of granular geomaterials is sensitive to their fabric, which exhibits anisotropic mechanical properties as a function of deposition history, microscopic fabric, and loading paths. Here, a new fabric-enriched continuum breakage model is proposed to examine the relation between elastic and inelastic anisotropy in granular materials and cemented granular materials. A microstructure model is first implemented in the framework of fabric-enriched continuum breakage mechanics (F-CBM), where the anisotropic behaviour prior to yielding is introduced through a symmetric second-order fabric tensor embedded in the expression of the elastic energy potential. The anisotropic strain energy storage prior to grain crushing leads to the rotation and distortion of the yield surface of cemented granular materials. Parametric analyses are performed to assess the overall capability of the model to characterize the anisotropic inelastic processes in cemented granular. It is shown that the proposed model can accurately predict the strong correlation between anisotropic elasticity and breakage-damage processes in cemented granular materials. When damage involving the skeleton is the dominant inelastic process, the size of the elastic domain contracts and the material exhibits augmented brittleness with the disintegration of cement. While breakage processes are predicted to dominate the response of lightly cemented granular materials resulting in hardening behaviour. This work can be further extended to dynamically capture the anisotropic response of cemented granular materials with water-sensitive mineral constituents by accounting for the evolution of microstructural anisotropy.
Rock mass substitute geometry theory (SGT) and 3D centroid sliding pyramid (CSP) method
Authors: Wu Wei , Yi Xiaokai , Zhu Hehua 
Published: May 2024

Abstract
Discontinuous analysis methods are typically used for the stability analysis of fractured rock masses with multiple sets of joints. Among various discontinuous methods, the key block theory (KBT) requires less data input, has a higher computational efficiency, and is suitable for wide-ranging engineering applications. Classical discontinuous numerical methods typically require complete boundary information for rock block units. However, current information-gathering methods can only capture information on rock surfaces. The proposed rock mass substitute geometry theory (SGT) overcomes this limitation by using local geometric information to equivalently represent the original geometric body simplifying subsequent analyses. A 3D centroid sliding pyramid (CSP) method is introduced for motion state analysis of a rock block that uses only the collinear faces of a block’s free surfaces. A comparison of CSP with KBT proves that CSP not only addresses the issue of collecting only surface information of rock masses but it significantly minimizes the computation scale. Additionally, a 3D discontinuous analysis program was developed, encompassing the entire process of rock mass information gathering, 3D discontinuous modeling, and 3D CSP analysis. The effectiveness and efficiency of the method were validated using stochastically generated models, while its practical engineering applicability was demonstrated at an engineering site.
Shale fault reactivation during hydraulic fracturing in the Sichuan Basin: Evidence from shear experiments and stress perturbation calculations
Authors: An Mengke , Zhang Fengshou , Yin Zhenyu , Elsworth Derek 
Published: May 2024

Abstract
Induced seismicity triggered during hydraulic fracturing for shale gas exploitation in the Sichuan Basin has aroused wide public concern with these earthquakes closely correlated with the reactivation of faults within the reservoir. The target shale reservoirs in the Sichuan Bain are currently located in the Longmaxi formation. To explore instability on these faults, we conducted shear experiments on simulated fault gouges under hydrothermal conditions to assess frictional stability and also evaluated the stress perturbations resulting from multistage hydraulic fracturing. Experimental results show that the frictional instability on these faults is primarily controlled by both mineral composition and the applied temperatures. With a decrease in the contents of phyllosilicate minerals or an increase in applied temperatures, the shale faults exhibit a transition from velocity-strengthening to velocity-weakening behaviour, indicating the potential for unstable fault slip. The stress perturbations resulting from multistage hydraulic fracturing were calculated from a dislocation model of the fluid-driven fracture. These results show that the stress changes resulting from multistage hydraulic fracturing are sufficient to reactivate adjacent unstable faults in the shale reservoir and trigger the seismicity. Our experimental and modelling results highlight the importance of shale composition, temperature, and stress perturbations on shale fault stability. These results have significant implications for understanding the shale fault instability and the potential triggering of induced seismicity during hydraulic fracturing in the Sichuan Basin.
Modeling the Fracturing Behavior Transition in Fractured Granite under Thermo-Hydro-Mechanical (THM) Condition
Authors: Li Mengyi , Zhang Fengshou 
Published: May 2024

Abstract
An in-depth understanding of the thermo-hydro-mechanical (THM) effects on rock fracturing becomes progressively important in natural energy exploitation projects. However, the failure mechanisms of fractured granite under THM conditions are very complex. To investigate the effect of THM treatment on the meso-macro fracturing behavior transition in fractured granite, a coupled thermo-hydro-mesostructure-based DEM (T-H-MSBM) model was developed to reconstruct rock microstructures and distinguish the THM responses of varying mineral grains, pores and micro-cracks in the fractured granite. Based on the T-H-MSBM, fractured granite was first generated in terms of large damage degree, and the comparisons of numerical compression simulations in the natural and fractured granites were carried out under the coupled conditions of temperature (25-225 °C) and pore pressure (0-12 MPa). The interplay of THM treatment and damage degree on the mechanical properties of fractured granite was revealed, and the main mechanisms affecting the varied macro mechanical properties were further discussed insight from the fracturing behavior transition in fractured granite during the THM-uniaxial loading process. The results indicate that both temperature and pore pressure exert the amplified deteriorating effect on the macro mechanical properties of fractured granite with increasing damage degree, while the temperature dependence becomes significantly more pronounced in the fractured granite with low damage degree. The unique distribution of initial cracks controlled by mineral characteristics can lead to large variability in the initiation of THM-induced tensile cracks, and hence to the emergence of multiple fragments in the fractured rock with large damage degree during the compression loading, especially under high pore pressure. The findings can provide important insights into geotechnical applications to achieve engineering safety and economic objectives. For example, during the process of deep resource extraction, we can adjust the reservoir reformation methods in a more reasonable and dynamic manner by considering the variations in the damage degree of fractured rock resulting from excavation disturbance.
Mechanical properties of nano-modified foamed cement paste
Authors: Zhang Z , Gao R F , Wang M Y , Ye G B , Liu S M 
Published: May 2024

Abstract
Foamed cement paste has been increasingly used as backfilling material in practice. The unique porous structure characteristic significantly influences the mechanical properties of foamed cement paste. This study conducted a series of laboratory tests to investigate the mechanical properties of nano-silica modified foamed cement paste. Foamed cement paste specimens with densities of 0.6 g/cm3 1.1 g/cm3 1.5 g/cm3 were prepared, incorporating nano-silica in varying concentrations from 1 g/L to 5 g/L. The density test and uniaxial compression test were conducted. The results show that the nano-silica improved the density inhomogeneity of the foamed cement paste and increased the peak strength. The optimal nano-silica content was 3 g/L in this study. This study offers a practical approach for enhancing the performance of foamed cement paste in engineering applications.
Research on shear characteristics of pile–soil interface under cyclic loading
Authors: Zhou Jie , Zhu Kefan , Liu Chengjun 
Published: May 2024

Abstract
Offshore wind turbine constructions are developing rapidly in China. Generally, large-diameter rigid steel piles are used in offshore wind turbine foundations. However, existing design methods for pile foundations with bearing capacity are often based on small-diameter flexible piles and are inapplicable to real situations. Simultaneously, thick layers of clay cover the fields. Therefore, the shear characteristics of pile–clay interface require examination to optimize design methods. A large-scale interface shear test model corresponding to laboratory tests is established using PFC software, and the micro-parameter values are validated. The simulation results well follow the laboratory test results, and the model accurately reflects pile–clay interactions during shearing. Based on the simulation model, the shear characteristics of the steel–clay interface under different normal loads, cyclic load frequencies, and cyclic load amplitudes are analyzed. With an increase in normal load, the shear strength of the steel-clay interface increases gradually, whereas it slightly decreases with an increase in the cyclic load frequency and amplitude; particularly, the effect of amplitude is significant. The mechanical response of clay at a mesoscopic scale is analyzed. Results show that the greater the normal load, the greater the horizontal displacement of particles. However, the influence of cyclic load frequency and amplitude is the opposite: normal load does not change the contact force distribution of soil particles, and clay volume change is determined by the normal load. Thus, this study provides support for bearing capacity prediction of offshore wind farm pile foundations.
Numerical model for suction anchor under vertical impact loading
Authors: Xu M T , Rui S J , Zhang S H , Zhang Y R , Guo Z 
Published: May 2024

Abstract
In marine engineering, suction anchors are widely employed as the supporting foundation for many types of fixed or floating structures. One of the important control conditions for the service of marine foundations is the impact loading in extreme environments. This study proposes a numerical model to predict the dynamic behavior of suction anchors under impact loading. A mass module is added to the numerical model to quantify the effect of anchor inertia. The t-z springs are positioned along the depth to reflect the soil layer stress and accurately calculate the skirt wall friction. Considering the seepage effect, the differential pressure development, internal soil stress loss and external soil stress enhancement are also reflected. Subsequently, the influence of anchor aspect ratio and loading history are investigated. As the foundation uplift movement is further pronounced, the friction resistance gradually works, resulting in the weakening of inertial force. The existence of pretension loading makes friction resistance take effect earlier, and accelerates its attenuation during the impact loading stage.
Evaluating efficiency of metro-led urban underground public space: a case study in Shanghai
Authors: Zhang Z Y , Ma C-X , Qiao Y-K , Peng F-L 
Published: May 2024

Abstract
Metro-led urban underground public space (UUPS) are among the most common and important types of underground and public spaces. The need to measure metro-led UUPS performance and improve urban planning and public services has facilitated the development of various evaluation methods. However, the essential performance aspects of efficiency and effectiveness are rarely balanced. Most methods focus on evaluating effectiveness while neglecting the cost incurred. This study proposed two sets of efficiency indicators of cost (input) and effectiveness (output) separately and used data envelopment analysis (DEA) to analyze the relative efficiency of 20 metro-led UUPS in Shanghai, China. The results indicated that the UUPS of People’s Square, Hanzhong Road, and Huamu Road were the most efficient. Whereas, the South Shanghai Railway Station UUPS and other five cases were neither technically efficient nor scale efficient; a waste of space volume was observed in half of the inefficient cases. Through comparisons of the results with previous studies, it was determined that different conclusions could be drawn when considering efficiency. Moreover, the evaluation framework based on the DEA method proposed in study paper can provide a comprehensive and holistic approach to guide metro-led UUPS planning optimization.
Modeling the Seepage-induced Damage in Water-Rich Fault Zones at Tunnel Faces by Double Point Material Point Methods
Authors: Li Z Y , Zhou M L , Huang H W 
Published: May 2024

Abstract
During tunnel construction, crossing water-rich fault fracture zones leads to water influx hazards at the tunnel face. Excavation exposes the fault, causing disturbances and changes in the hydraulic gradient. Thus, the tunnel face becomes a low hydraulic head surface. The naturally high permeability of the fracture zone provides a pathway for groundwater flow, resulting in water seepage along the fracture zone and subsequent water influx at the tunnel face. To investigate this interaction, a two-phase double-point material point method was employed aimed at developing a coupled fluid-solid numerical model for excavating submarine fault tunnels. The model incorporates solid-liquid phase interaction, including rock mass permeability, water viscosity, and tunnel geometry. It analyzes the changes in the liquid-phase flow velocity, pore water pressure, and particle trajectories in the fractured zone ahead of the working face after the fracture zone is exposed, revealing the dynamic evolution of water influx following excavation. Additionally, this study discusses the impact of the solid-liquid phase permeability coefficients on the range of water influx hazards. The research findings demonstrate that the two-phase double-point material point method effectively captures the seepage and water influx processes, offering valuable insights into the mechanisms of sudden water influx in tunnel engineering.
In-site Investigation of Rock Mass Structure Effect on Tunnel Smooth Blasting Quality
Authors: Wang Jianxiu , Cao Ansheng , Liu Jiaxing , Yin Yao , Wang Guotao , Zhou Xiaobo 
Published: May 2024

Abstract
Smooth blasting controls tunnel excavation contours and rock stability; however, it can lead to overbreaks and underbreaks due to rock mass anisotropy. Studying the Zigaojian tunnel of the Hangzhou-Huangshan Expressway, this research examined the effect of rock mass structure on smooth blasting quality. Four rock mass structure types–massive, layered, and cataclastic–were determined through manual measurements, three-dimensional scanning, point loading tests, and wave velocity measurements. The blasting overbreak and underbreak of the tunnel section were measured using a tunnel section laser distance measuring instrument, and the relationship between the blasting overbreak and rock mass structure type, surrounding rock grading, structural plane spacing, structural plane number, uniaxial compressive strength, and density was studied using multiple regression analysis. The results show that the overbreak area and maximum overbreak increase as the integrity of massive, massive, layered, and cataclastic rock masses decreases. The intersection of the rock mass structural plane and tunnel section was overbroken. The overbreak is positively correlated with the rock structure type, surrounding rock grading, and structural plane number and negatively correlated with the uniaxial compressive strength, density, and structural plane spacing. The results of this study can provide a reference for smooth blasting in similar projects.