bluuebunny/crossref_metadata_2025_split huggingface dataset:
A prediction model of maximum dry density of over coarse-grained soil
Authors: Jia Mincai , Zheng Yiming 
Published: May 2024

Abstract
The control of maximum dry density is an important issue for over coarse-grained soil. A theoretical formula of the maximum dry density for over coarse-grained soil was derived, which is related to the maximum dry density of the original soil, particle density, and mass fraction of giant particles in the mixed soil. Maximum dry densities of seven groups of mixed soil were calculated by the discrete element method (DEM) and theoretical formula, and the results showed that the maximum dry densities obtained from the DEM were always lower than the results calculated by theoretical formula, and the difference increased with the increase in giant particle proportion. The volume growth coefficient was proposed to describe the increase in pore volume of the mixed soil caused by the embedding of giant particles, and the maximum dry density model for over coarse-grained soil was proposed. The results showed that the model fitted well to the DEM results, validating the high rationality and reliability.
Constitutive and experimental study of unsaturated fine-grained soils over a wide suction range
Authors: Zhou G Y , Shi Z H , Qian J G 
Published: May 2024

Abstract
The instabilities exhibited by unsaturated fine-grained soil, stemming from coupled hydro-mechanical phenomena, represent crucial engineering characteristics essential for geotechnical designs. This study introduces a constitutive model for unsaturated fine-grained soils, incorporating the framework of sub-loading surface plasticity. The model integrates Bishop’s effective stress and capillary degree of saturation as basic variables, while also addressing the distinct influences of soil volume change on capillarity and adsorption mechanisms. Validation of the proposed model is conducted using a diverse set of experimental data derived from suction-controlled triaxial compression tests conducted under low and high suction conditions. The results demonstrate that the new constitutive model can achieve a reasonable agreement with the observed data.
A review on thermal conductivity of unsaturated bentonite
Authors: Ye W M , Shao C Y , Lu P H , Liu Z R , Chen L 
Published: May 2024

Abstract
As unsaturated bentonite is used a buffer/backfill material in the construction of engineered barriers for high-level nuclear waste disposal, understanding its thermal properties is crucial for maintaining the operational stability of the repository. This review paper synthesizes research on the thermal conductivity of unsaturated bentonite, encompassing aspects of heat transfer mechanisms, measurement techniques, influencing factors, and prediction models. The results highlight that the transient and steady-state methods have emerged as the predominant techniques for measuring the thermal conductivity of unsaturated bentonite owing to their efficiency and the prevention of water redistribution within the sample throughout the testing phase. Factors such as dry density, degree of saturation, additive content, and temperature were observed to positively influence the thermal conductivity of unsaturated bentonite, whereas an increase in the ion concentration of the pore fluid decreased the thermal conductivity. The prediction models for the thermal conductivity of unsaturated bentonite are categorized into empirical, normalized, and theoretical models. Although empirical and normalized models provide some insight, they suffer from a lack of theoretical foundation, and the parameters they incorporate often lack clear physical significance, complicating their practical application despite their capacity to represent the multifield coupling characteristics of thermal conductivity. The advancements in microscopic testing methods and computational technology herald the potential of mesoscale models and machine learning as formidable tools for predicting the thermal conductivity of unsaturated bentonite, suggesting a promising direction for future research.
Effect of volumetric deformation on saturation of unsaturated soils under constant suction
Authors: Chen Ke , Liang Fayun 
Published: May 2024

Abstract
The soil–water retention curve (SWRC) represents a fundamental relationship in the study of unsaturated soils, where volumetric deformation plays a crucial role in shaping the water retention characteristics by impacting the pore size distribution. This study conducted a thermodynamic analysis to derive a relationship between the effective stress parameter and the water retention properties of unsaturated soils. Consequently, a streamlined formula was introduced to forecast the impact of volumetric deformation on saturation at constant suction. This formula, incorporating a singular parameter from the effective stress parameters equations, can be seamlessly integrated with any prevailing SWRC model to characterize the influence of volume deformation on the SWRC. The effectiveness of the proposed model was corroborated through seven sets of experimental data spanning various soils, affirming its capability to precisely describe the water retention behavior of deformable soils under deformation.
Hydro-mechanical model for small-strain stiffness of unsaturated soil
Authors: Wang Fangtong , Shen Kanmin , Shan Zhigang , Wang Yong 
Published: May 2024

Abstract
This study aims to investigate a novel method for predicting the small-strain stiffness of unsaturated soil. A hydro-mechanical model is proposed to estimate the small-strain stiffness of unsaturated soil with various matric suction and stress states. A series of saturated and unsaturated bender element tests are conducted, and the test results indicate that the small-strain stiffnesses of saturated and unsaturated soil have similar changing trends with the variation of the stress state. The small-strain stiffness of unsaturated soil is calculated by the proposed model based on the test results of saturated soil. The model has two parameters that have a physical meaning and can be measured by tests. Thus, combined with the mature prediction model and measurement method of saturated soil and the proposed hydro-mechanical model, the complex unsaturated bender element tests are unnecessary. The proposed model is anticipated to be of practical value for solving engineering problems during the determination of small-strain parameters in the design of pits and foundations.
Numerical analysis of the indentation of a poro-elastoplastic half space by a rigid cylinder
Authors: Zhang Tiansheng , Liu Ming , Huang Haiying 
Published: May 2024

Abstract
Poro-elasto-plastic cylindrical indentation as a means for material characterization is explored numerically in this work. When a rigid cylinder is being pressed into a semi-infinite, fully saturated poroelastic medium via step displacement loading, undrained and drained elastic constants are reflected in the responses at the early and late times, while hydraulic diffusivity is manifested in the transient behavior. Such an indentation test can therefore be used in principle to identify material parameters. For geomaterials, plastic deformation may occur due to the indentation action. How the hydromechanically coupled indentation response is affected by plastic deformation is investigated here using finite element analysis. We consider the problem to be plane strain with frictionless contact. Drucker-Prager failure criteria with and without a cap are considered. We show that if there is only limited plastic deformation, the concept of using the transient response for determining hydraulic diffusivity may be extended from poroelasticity to poro-elasto-plasticity.
Experimental study on quantitative drilling of composite rock mass
Authors: Liu Zhenghao , Wang Jing , Shi Shaoshuai , Sun Fahe , Li Quanjiang , Fu Shinong , Chen Yuning 
Published: May 2024

Abstract
Effective identification of the interface position and characteristics of rock formations is important for identifying dangerous sources of structural deterioration in rock formations. To explore the sensitivity of the drilling parameters to changes in the formation characteristics and the influence of the interface on the drilling response of a composite rock mass, 28 test models with varying interface inclinations are designed. Laboratory quantitative drilling test research is conducted using the laboratory digital drilling test system at Shandong University. The influence law of the rock interface dip angle on the drilling parameters is established. Empirical equations for estimating the peak drilling pressure and peak drilling torque at the rock interface and the steady-state drilling pressure, drilling torque, and their differential values are established using multiple regression analysis. This study is expected to serve as a reference for improving digital drilling measurement accuracy.
A fast and automatic establishment method of the calculation formula for the tunnel face safety factor based on analytical solution
Authors: Man Jianhong , Huang Hongwei , Chen Jiayao 
Published: May 2024

Abstract
Assessing rock tunnel face stability when constructing mountain tunnels is of utmost importance because it is influenced by various factors, including the tunnel diameter, depth, excavation dimension, geological strength index, uniaxial compressive strength, and Hoek-Brown constant. This study established a tunnel face stability database based on analytical solutions that considered the correlation between the influencing parameters. Finally, a safety factor prediction equation was constructed by combining response surface methodology and the multivariate adaptive regression spline algorithm. The results of this study find applications at construction sites and provide a reference for the rapid evaluation of rock tunnel faces during construction.
Damage characteristics of rock induced by unloading in hole under true triaxial boundary stresses: Experimental study
Authors: Xiao Y , Wang S F 
Published: May 2024

Abstract
In order to study the effect of unloading of underground rock excavation on the stability of surrounding rock, the true triaxial compression (TTC) and coupled true triaxial compression and in-hole loading-unloading tests (TTC-HU) were conducted on hollow cubic rock (100mm × 100mm × 100mm). The experimental results indicate that the compressive strengths of the specimens increase as confining pressure increases in the equal biaxial stressand increase with increasing intermediate principal stresses in the unequal biaxial stress. At low confining pressure (σ < 30 MPa), the internal stress at unloading damage in the hole of hollow cubic specimen increases with the increase of the three-directional boundary stresses. At high confining pressure (σ ⩾ 30 MPa), the specimen will not be damaged during the entire unloading process in the hole. The damage mode of the specimen is dominated by tensile damage. The shape of the holes in the specimens did not significant change, and hole wall of specimen have layered destruction along the circumference in low confining pressure. In high confining pressure, the hole area of the specimen undergoes significant deformation damage, forming a V-groove along the direction of the minimum principal stress, and the wall of the hole is completely peeled off. This study can reasonably predict the actual engineering damage patterns and guide the optimization of surrounding rock support.
Key principles of stress control method
Authors: Xiao Y M , He M C , Qiao Y F , Peng M L 
Published: May 2024

Abstract
Underground excavation would cause two main excavation effects: (1) stress redistribution, including radial stress decrease and tangential stress concentration; and (2) surrounding rock degradation. Comprehensive consideration of excavation effects is crucial to prevent underground engineering disasters. However, the two excavation effects are not considered in the predominantly used Platts pressure arch theory, whereas the New Austrian tunneling method is focused on the full utilization of the strength of the surrounding rock. Construction designing using these methods could lead to disaster deep underground. Thus, in this study, the stress control method (SCM) was proposed to comprehensively consider the two excavation effects. The following two key SCM principles were introduced in this study: (1) adopt the largest possible prestressing force to increase the low radial stress caused by excavation; (2) timing of support should be as early as possible to minimize surrounding rock deterioration. The application principles of SCM in hard rock tunnels and soft rock tunnels are explained
Quasistatic progressive crack propagation behavior of crystalline rocks based on SCB tests
Authors: Zhao Cheng , Zhao Yinghui , Xing Jinquan , Xiang Fubin , Qian Yuan 
Published: May 2024

Abstract
To explore the influence of mineral grains on the mechanical strength and crack propagation behavior of rocks, this study investigates the quasi-static crack propagation characteristics in four types of granular structured rocks (three varieties of granite and one type of diabase rock) through a semi-circular bend three-point bending test. The implementation of a servo-controlled crack-opening displacement mechanism facilitated the realization of quasistatic crack propagation. The entire experimental procedure was documented on a camera. Subsequently, the quasistatic propagation and development of cracks in crystalline rocks were examined using digital image correlation, whereas the distribution of mineral grains and their relationship with the pattern of crack evolution were investigated under optical microscopy. The paths of the cracks exhibited noticeable deviation, which were further influenced by the mineral grains. Specifically, cracks tended to circumvent harder minerals while gravitating towards softer ones, highlighting the significant role of mineralogical composition in determining the fracture behavior of granite.
Study on the characteristics of granite rock impact crack based on grain-based model
Authors: Cao Ansheng , Wang Jianxiu 
Published: May 2024

Abstract
The type and heterogeneity of minerals control the initiation, aggregation, and expansion of rock blasting cracks and significantly affect the rock failure process. Granite was used to investigate the law of rock cracking under impact loading at the scale of mineral particles, and a two-dimensional grain-based model (GBM) was developed using PFC based on CT) scanning and laboratory mechanical tests. The GBM’s reliability was validated using laboratory uniaxial compression tests and numerical simulations. The specimen failure modes and evolution of microcracks during rock impact were analyzed, as well as the impact cracks’ characteristics under various impact velocities. The findings show that the GBM can simulate the microfracture behavior of several types of mineral fractures during rock impact. The evolution of granite cracks under impact loading can be divided into three stages: rapid growth, decreased growth, and gradual stabilization. The impact failure cracks of the samples were primarily tensile and intragranular. Granite’s tensile and shear fractures and intergranular and intergranular cracks of granite exhibit various trends with varying impact velocities. The GBM is viable for researching the dynamics of crystalline rocks and is a powerful tool for exploring the dynamic characteristics of rocks at the mineral particle level.
Seismic source of rock drill and its application in in-situ vibration monitoring of rock mass
Authors: Liu Z , Wang W , Li Q , Wang J , Chen Y , Zhang R , Zhou D 
Published: May 2024

Abstract
This study suggests the use of a seismic source of a rock drill as a new excitation method for real-time monitoring of the vibration frequency of rock masses in tunnel engineering. In this study, a laboratory rock drill seismic source test system was developed. The rock mass excitation and vibration response under real in situ stress were simulated, and a natural frequency test of different lithologic materials under various in situ stresses was carried out based on the developed system. Empirical equations for estimating natural frequency were established using regression analysis. The test results show that (1) the laboratory rock drill seismic source test system exhibits good performance and can simulate the horizontal excitation process of the tunnel rock drill. Rock drill excitation may be used as the seismic source to continuously measure the in-situ vibration information of the rock mass. (2) The natural frequency of rock is positively correlated with rock elastic modulus and geostress and negatively correlated with rock density. This is not directly related to the seismic source.
Plastic zone and surrounding strain analysis in a lined cavern for compressed air energy storage subjected to cyclic high internal gas pressure and temperature
Authors: Wei Chao , Zhao Cheng , Zhao Chunfeng , Qian Yuan , Zhou Biaohe 
Published: May 2024

Abstract
In the context of compressed air energy storage (CAES) technology, the strategic excavation of hard rock caverns is pivotal for overcoming geological challenges and advancing CAES deployment. This study adopts a circular profile for the cavern and investigates the impact of variables such as cavern diameter and depth. Considering the influence of cyclic internal gas pressure, temperature fluctuations, and potential leakage on the cavern, a thermo-hydro-mechanical coupled numerical model is developed using Comsol software. This model, grounded in classic elastoplastic constitutive relations, aligns with the conditions of a proposed project. It facilitates the computation of the plastic zone and surrounding strain for both the cavern lining and adjacent rock, post-excavation and throughout a typical ‘charging-storage-discharging-storage’ operational cycle. Through detailed analysis, the study delineates the variations and characteristics of the plastic zone and surrounding strain, thereby providing a solid foundation for a comprehensive examination of cavern stability, and the design of linings and sealing mechanisms.
Highway tunnel crossing fault zones with water-rich highly weathered granite
Authors: Shi Zhou , Xu Jinfeng , Xie Xiongyao , Niu Gang , Xiao Zhonglin 
Published: May 2024

Abstract
This study focuses on the Tianshengqiao Tunnel on the Linshuang Expressway in Lincang City, Yunnan Province, China. By combining the transient electromagnetic method, and geological radar geophysical exploration methods, joint fissures and water abundance in the surrounding rock of the tunnel were predicted. Simultaneously, combined with engineering disasters, such as water inrush and seepage in the surrounding rock during engineering practice, a numerical calculation model for the grouting reinforcement of granite mixed-rock tunnels considering the construction process was established using finite element software. The results indicated that the joint fissures in the tunnel were well-developed and exhibited a disorderly trend, showing an open shape. Accompanied by high humidity in the excavated rock mass, the overall water outflow is mainly as strands, with a large amount of water outflow, especially at the arch crown or left arch waist. The difference in the settlement values of the surrounding rocks at different depths within the grouting circle of the tunnel was relatively small, whereas that outside the grouting circle was significant. The larger the scope of the tunnel grouting circle, the smaller the overall deformation of the surrounding rock after the closure of the tunnel support structure.
Numerical Simulation of Tailings Mortar Flowing from Dam Break by Variable Concentration Two-phase Flow Algorithm
Authors: Yang Yi , Zhou Xiaowen 
Published: May 2024

Abstract
A dam break accident of tailings pond may result in serious loss of the residents' lives and property, and usually leads to surrounding environmental disaster. Accurately calculating the flowing distance and inundation range of discharged tailings is important but remains to be solved. The main feature of tailings mortar movement is that solid particles continue to sink and accumulate during the flow process, which makes the solid concentration in the mortar constantly change, thus altering the rheological properties of the mortar. Therefore, the advancement of tailings mortar is a kind of two-phase unsteady flow with variable solid-phase concentration. In conventional numerical calculations of tailings flow, the rheological parameters of the Bingham model used are given fixed values with no consideration of concentration change, resulting in inaccurate calculation results and difficulty reflecting the phenomenon of tailings sands accumulation along the way. In this paper, a variable concentration two-phase flow model is proposed and then applied to a typical tailings dam failure case. The flow features and inundation range of the tailings mortar are analyzed and are found to be basically consistent with the field investigation, which means the proposed two-phase flow algorithm is reasonable and reliable.
Assessment of Durability and Resilient Strain Deformation of Expansive Subgrade Treated With Nano-Slag-Based Geopolymer
Authors: Aneke Frank I. , Kalumba Denis 
Published: May 2024

Abstract
Nano-geopolymer binders (NGB) of 5%, 10%, 15%, and 20% concentration were used to stabilize expansive subgrade soil against strain deformation, as well as to improve its durability. The composites were subjected to a series of zero-swelling, wetting (W-D) cycles, and dynamic resilient modulus tests to determine the subgrade resilient strength against 100,000 applied repetitive loads (ARL). The results revealed that the resilient moduli of the stabilized and unstabilized subgrade soils exhibited strain-hardening responses at low cyclic stress levels. Therefore, the rate of plastic strain deformation became microscopically negligible, and the tested subgrade was considered stable at this stage. Conversely, at high cyclic stresses, the nano-geopolymer-stabilized subgrade continued to exhibit strain hardening between 80,000 and 100,000 ARL. The unstabilized subgrades exhibited strain softening at an ARL of 20,000 owing to the poor adhesion between the NGB and soil particles, leading to excessive strain deformation. The results revealed that the W-D resistance of the treated subgrade was up to 96% compared to the unstabilized subgrade, which lost over 30% of its particle mass after the 6-number cycle. This study indicates that the NGB-treated subgrade possesses the potential to sustain medium-to-high ARL loads owing to improved stiffness through polymerization reactions.