bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

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

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.
Key technologies for improving resilience of super-large diameter shield tunnel affected by large variable loads underneath the Yellow River
Authors: Chen J
Published: May 2024

Environmental conditions may have a significant impact on the construction and operation of underground works, and sudden changes in environmental conditions may lead to underground engineering damage. Considering the Yellow River crossing tunnel on Huanggang Road in Jinan as an example, this paper analyzes the mechanical performance of the lining of the shield tunnel with an external diameter of 16.8 m, which faces the challenge of large variable loads in operation stage, such as deep riverbed erosion and deposition, large-scale heightening of river embankment, seasonal changes in groundwater level, and key technologies for improving the resilience of tunnel structure are proposed accordingly. The results can not only assist in the construction of the super-large-diameter shield tunnel project in Jinan City but also provide technical support for other shield tunnel projects crossing rivers, lakes, and seas.
Field research on supersized rectangle pipe-jacked tunnels beneath a navigable river in the urban area
Authors: Fang T , Jiang Z , Gao X
Published: May 2024

With technological progress in recent years, supersized rectangular jacked pipe tunnels have been increasingly used for developing urban road-crossing nodes, owing to their convenient construction and economic benefits. However, owing to the weak waterproofing performance of the joint, jacked supersized rectangular pipes have been employed beneath a navigable river. This study used on-site monitoring data of an underground expressway with supersized rectangular jacked pipe tunnels in Shanghai. Additionally, we analyzed the deformation of the ground surface and embankment and the mutual influence of jacked adjacent pipes. The results revealed the following. 1) the over-excavation of the jacked pipe causes partial surface subsidence. The jacking parameters were adjusted through feedback to control the surface deformation. 2) The spatial deformation of the old embankment were stabilized, suggesting the successful realization of micro-disturbance jacking construction. 3) The secondary disturbance of the soil due to post-construction causes a slight sinking and tilting trend of the former jacked tunnel.
3D concrete printing for tunnel linings: Opportunities and challenges
Authors: Tao Yaxin , Yuan Yong
Published: May 2024

The use of shotcrete for hard rock tunnel linings has drawbacks such as irregular surfaces and rebounds. By contrast, extrusion-based 3D concrete printing presents a promising solution with precise deposition and reduced rebound. This study discusses the potential of 3D printing for tunnel linings, focusing on mitigating shear failure and addressing interfacial detachment. Achieving high strength early for stable adhesion to rock surfaces is paramount for countering shear failure. A twin-pipe pumping system was introduced utilizing a helical static mixer to blend concrete involving chemical triggers, effectively managing the stiffness and fluidity during pumping. In addition, the adhesion to the substrate must be addressed. Based on the above discussion, this study offers insights into the fundamental challenges, paving the way for advancing extrusion-based 3D concrete printing for tunnel linings.
Force and wear prediction model of disc cutter under compression shear failure mode based on dense core–cavity expansion theory (U-713)
Authors: Su H , Guan Z C , Deng T , Yang Z Q , Qin J P , Zheng L
Published: May 2024

Calculating disc cutter wear and predicting wear life are long-standing issues affecting the efficiency and cost of tunnel boring machines (TBMs). During the TBM excavation process, the wear of the disc cutter is a comprehensive outcome of the interaction between the tool and rock. Studying the mechanisms of tool rock breaking and wear can assist in developing a more precise model for predicting cutter wear. Therefore, based on the rock-breaking and wear mechanisms of a cutter, this study developed a model for predicting the cutter wear rate and life. The model is based on the theory of dense core–cavity expansion combined with the motion state of a cutter. First, the TBM excavation process and rock-breaking mechanism of a cutter were analyzed in detail. A cutting force model under the compression shear failure mode based on the dense core–cavity expansion theory was established. Based on the force model, a prediction model for the wear rate and life of the disc cutter was established, considering the working characteristics and wear mechanism. Furthermore, the impact of penetration on the prediction model was investigated. In addition, to demonstrate the practicality of the method, this study conducted a comprehensive examination using engineering examples. The results showed that the average difference in the cutter average wear rate using the developed model was less than 3% compared with the actual engineering result. In addition, the average difference in the wear life rate was less than 5%. Finally, the developed prediction method was compared with other models. The wear rate fitting accuracy was improved by 4.91–10.85% and the wear life fitting accuracy was improved by 5.11–12.19% by the developed method. This improvement confirms the reasonableness and reliability of the method. This method can estimate the wear rate and lifespan of a cutter more accurately and reliably than other methods, providing a practical tool to TBM engineers to make informed decisions and optimize tool replacement programs.
Assessment of Building Response Supported on Shallow Foundation Due to Tunnelling in Cohesionless Soil
Authors: Bayen Asit , Samanta Manojit
Published: May 2024

The depth of foundations significantly influences the building response due to tunnelling-induced ground movement. The present study investigates the responses caused by tunnelling on buildings supported on isolated footings. The response of buildings supported on shallow foundation systems due to progressive tunnelling is investigated through experimental and numerical methods. A three-dimensional finite element analysis (3D FEM) has been developed to evaluate the response of an existing reinforced cement concrete (RCC) building underpasses a circular-shaped tunnel in cohesionless soil. The model includes soil strata, footings, super-structure, and tunnel. Different parametric studies, i.e., C/D ratios, tunnel volume losses, and eccentricity of the building, have been considered in the present study. A scale-down model of the tunnel and building is prepared in the laboratory. The scale-down model simulates the volume loss during tunnelling and evaluates the response on surface and building components due to tunnelling. The surface settlement, total and differential settlement of the foundation, and induced strain on lining and building elementals are estimated. The numerical model is benchmarked with the experimental study conducted in the laboratory. It is observed that the numerical method agrees well with the experimental investigation. The responses of buildings supported on shallow footings are compared with available literature. The findings of the present study will be useful for the hazard estimation of existing buildings situated along/adjacent to a proposed alignment of the tunnel.
Numerical study on the influence of excavation slope on the structural behavior of ground penetrating shield tunnels
Authors: Wang Z , Li H , Liu Z , Huang J , Zhu Y
Published: May 2024

The ground penetrating shield technology (GPST) is a fast shield tunnelling method, wherein the shield is launched and received at the ground surface without constructing deep and large working shafts. With regard to the notable sloping excavation characteristics of the GPST, this study established a three-dimensional numerical model to analyze the impact of the excavation slope on the structural response of the tunnel lining based on the South Longshui Road Cross-river Tunnel project in Shanghai. The results indicate that the circumferential earth pressure acting on the lining is determined by both the buried depth and decomposition angle induced by the change in the excavation slope. The distribution of the earth pressure along the longitudinal direction may be affected by the excavation slope, and this subsequently affects convergence deformation of the tunnel. An increase in the excavation slope equalized the distributed force acting on the lining. In addition, the existence of circumferential joints exaggerates the impact of the excavation slope on the differential convergence between adjacent rings. A larger excavation slope resulted in a decrease in the proportion of convergence deformation caused by the longitudinal joints. These findings can provide important guidance for controlling the ovalization and dislocation behaviors of GPST.
Thermal-force response analysis and applicability evaluation of strata energy shaft in Shanghai
Authors: Zhou Jie , Wang Xin , Xu Jie , Zhang Zhenguang , Ban Chao , Liu Chengjun , Zhou Huade , Guo Zhongqiu , Liu Qi
Published: May 2024

Energy underground structures, such as energy shafts and tunnels, are a class of energy-saving and environmentally-friendly underground structures. They can be used as shallow geothermal energy harvesting systems for heat exchanges with the ground. Theoretical research and practical applications of energy shafts are still in the initial stages, and related tests are still relatively few. This study used the Shanghai Taihe energy shaft test section as the research background. The results of the thermal force response test of the energy shaft was numerically analyzed using the COMSOL software and compared with that of Beijing Qinghuayuan energy tunnel for applicability evaluation and analysis. The results show that the Shanghai strata energy shaft has a better heat transfer capacity than the Beijing strata energy tunnel owing to the different geological environments and is more economical. Simultaneously, the temperature stress generated in the heat transfer process of the Shanghai Strata energy shaft was smaller than that of the Beijing strata energy tunnel, which is safer. Therefore, underground energy structures can be widely applied to the Shanghai strata, which can significantly improve economic applicability while ensuring safety.
Impact of small-angle shield undercrossing on existing tunnels
Authors: Fu Y M , Ding W Q , Qiao Y F
Published: May 2024

A three-dimensional finite element model was developed to investigate the effects of small-angle tunnels on existing tunnels in terms of surface settlement, arch bottom settlement, and ellipticalization of existing tunnel linings. The model simulated two small-angle tunnels crossing two existing tunnels. The maximum surface subsidence was observed at the recently excavated tunnel centers. The presence of existing tunnels reduced surface subsidence caused by ring-by-ring excavation. Surface settlement followed a “W” curve pattern, with two local minima gradually getting close as the tunnel was excavated. The maximum value of the arch bottom settlement of the existing tunnel gradually approached the intersection of the existing tunnel and the newly excavated tunnel. When the absolute value of the rate of change of the arch bottom settlement was high, the tunnel produced a large inter-ring misalignment. The line connecting the centers of the existing tunnel and recently excavated tunnel was parallel to the major axis direction of the ring after the deformation of the lining on the existing tunnel. Therefore, a small-angle tunnel passing through an existing tunnel may result in misalignment and torsion of the existing tunnel, requiring careful monitoring of the inter-ring bolt force to ensure safety.
Soil structure effect on soil erosion potential
Authors: Lin Yunjie , Lin Cheng , Liu Minghao , Evans David
Published: May 2024

Soil erosion poses a significant threat to water-related infrastructure such as bridges, dams, quays, and levees by detaching and transporting soil grains downstream, thereby compromising the structural support of these installations. While erosion damage is acknowledged in current design practices, understanding soil erosion parameters requires scrutiny. However, existing soil erosion databases mainly rely on reconstituted soil samples, which may differ substantially from in situ erosion due to alterations in soil structure. This study scrutinizes and contrasts the erodibilities of in situ and reconstituted soils. In situ soil samples were obtained using thin-walled Shelby tubes from Victoria, Canada, while reconstituted specimens were prepared in a slurry state and consolidated to match the overburden pressure on-site. A custom rotational erosion testing apparatus facilitated erosion testing on both Shelby tube and reconstituted specimens. The findings shed light on the influence of soil fabric on soil erosion potential, an aspect currently lacking in comprehensive understanding.
Proposal of a practical stability probability model for cut slopes reflecting characteristics of weathering and angle of stratification
Authors: Zhuang Huimin , Yasufuku Noriyuki , Kasama Kiyonobu , Ishikura Ryohei
Published: May 2024

This research evaluates the stability of cut slopes, considering the effects of weathering and the angle of stratification. Incorporating both a weathering degree index and a factor of safety, we developed a novel formula to assess the temporal deterioration of cut slopes. Utilizing this formula, logistic regression was conducted to ascertain cut slope stability. We used the Hierarchical Bayesian model to refine the parameters of the logistic regression function, culminating in the formulation of a comprehensive slope stability probability prediction model. The model’s predicted stability probabilities for diverse cut slopes exhibited a compelling congruence with empirical data upon validation. Importantly, this approach provides expressway management authorities with a tool to preliminarily assess whether longstanding in-service cut slopes require intervention or stabilization measures.
Optimal earthquake intensity measures for seismic vulnerability assessment of concrete-faced rockfill dams
Authors: Khalid Muhammad Irslan , Fei Jianbo , Chen Xiangsheng
Published: May 2024

Earthquake intensity measure (IM) selection is crucial for developing probabilistic seismic demand models (PSDMs). This study explored the optimal IMs that can be utilized in PSDMs for concrete-faced rockfill dams (CFRDs). A two-dimensional nonlinear dynamic analysis of a CFRD was performed to assess its response to earthquake ground motion. A numerical model of CFRD was developed using the commercial software LS-DYNA with an advanced hysteretic soil model. A total of 20 earthquake IMs were selected for regression analysis. The regression analysis was performed between IMs and the damage index (DI). The IMs were evaluated through a selection process based on the goodness of fit as well as their efficiency, practicality, and proficiency. Accordingly, a range of optimal IMs was determined. The results indicated that effective design acceleration (EDA) is the best earthquake IM correlating with the seismic response of dam settlement and can be considered the optimal IM, whereas peak ground displacement (PGD), ratio of peak ground velocity to peak ground acceleration (PGV/PGA), and predominant period (Tp) are the less efficient. The fragility curves and surfaces were developed employing both scalar and vector IMs for CFRD.
Vertical vibration of a rigid disc over a transversely isotropic and layered poroelastic half-space
Authors: Zhang Z Q , Pan E N
Published: May 2024

A novel semi-analytical method is proposed for solving the vertical vibration of a rigid disc over a transversely isotropic and layered poroelastic half-space. The fundamental solutions in the layered poroelastic half-space under a vertical patch load on the surface are solved in terms of the newly developed Fourier-Bessel series (FBS) system of vector functions and the unconditionally stable dual-variable and position method. The expansion coefficients in FBS system are discrete, as such the computational efficiency is greatly improved and the accuracy is better than the commonly used integral-transform methods. By virtue of the superposition method, the Green’s function due to vertical ring load is derived in the transform domain. By making use of the integral least-square scheme, the densities of a series of ring loads discretized within the disc area are determined. Finally, the dynamic vertical compliance is derived via the balance between the external applied force and the induced total contact traction. After verifying the reliability of the developed solution, selected numerical examples are presented to investigate the influence of material properties and excitation frequency on the forced vibration of the rigid disc.
Numerical evaluation of seismic response of corroded bridges
Authors: Nie Y , Li J , Zhou P , Liu G
Published: May 2024

Traditional seismic analyses of concrete bridges mainly focus on new bridges, ignoring the effect of durability on the performance, which causes limitations. Research on the seismic performance of corroded bridge piers considering the modal period of the piers is of utmost importance. The corrosion process of steel bars under chloride-ion erosion is simulated based on Faraday’s law, and the time-varying law of the performance degradation of reinforced concrete materials is calculated. Subsequently, a finite-element model of the bridge structure is established using the OpenSees platform. Two seismic waves are selected to analyze the time history within the established finite element model. Considering the influence of the pier modal period, the seismic capacity, and dynamic characteristics of a bridge exposed to a chloride-ion environment are evaluated. This study serves as a robust source of technical support for the comprehensive study of vulnerability analysis, encompassing the assessment of the risks associated with chloride-ion-induced corrosion degradation and seismic hazards.
Analysis of basalt fiber reinforcement on static shear properties of Beibu Gulf sea sand
Authors: Wang Jia-quan , He Yu , Tang Yi , Zhang Tao-yi
Published: May 2024

Basalt fibers are a reinforcing material with excellent mechanical properties and durability. In contrast, although Beibu Gulf sea sand is widely in engineering, it exhibits low strength and poor stability, which can be improved by adding basalt fibers. In this study, the effects of fiber content, fiber length, and effective confining pressure on the static shear strength of fiber-reinforced sea sand were investigated using a triaxial shear test. The maximum improvement on the static shear characteristics and deformation resistance of sea sand were achieved for a fiber content and length of 0.8% and 12 mm, respectively. The cohesion and internal friction angle of sea sand were improved and the secant modulus and strain before and after basalt fiber reinforcement showed a nonlinear attenuation tendency. The reinforcement effect coefficient R and the basalt fiber content under different dosages were in accordance with the law of the Gaussian function. The value of R conformed to a linear growth and exponential function law under different fiber lengths and effective confining pressures, respectively. This study provides a solid theoretical basis for the sustainable utilization of sea sand resources and fiber reinforcement for road and coastal protection engineering in the Beibu Gulf region.
Obliquely incident seismic response of subway stations following urban soil internal erosion
Authors: Wei S M , Wang C , Liang F Y , Qin T X
Published: May 2024

Urban groundwater infiltration resulting from tropical storm rainfall can lead to internal soil erosion and ground subsidence. The long-term effects of these phenomena may result in uneven settlement of the subway system, posing risks to its safety and operational integrity. Suffusion poses a significant hazard to long-term subway operation. It is a type of soil internal erosion characterized by the migration of fine particles from the pore channels between coarse particles. This study focused on the performance degradation of different gap-graded sands caused by internal erosion, observed through triaxial compression tests. Using the cap plasticity model and considering mechanical parameters before and after soil erosion, a refined two-dimensional finite element model of a soil subway station structure based on ABAQUS was developed to analyze the deformation and damage pattern of the subway structure resulting from soil internal erosion and earthquake. The results of this study demonstrated that localized internal soil erosion significantly contributes to uneven settlement in subway stations, potentially compromising their seismic performance during oblique seismic excitations.
Numerical simulation of bending characteristics of geosynthetic encased stone column
Authors: Qin Xiang Zhen , Chen Jian Feng , He Peng Chen
Published: May 2024

A numerical model of the cantilever bending structure of a geosynthetic encased stone column (GESC) of length 3 m and diameter 0.3 m was established using Z-Soil. The aim was to analyze the stress distribution and bending characteristics of the GESC under a bending load and to investigate the impact of encasement strength, encasement stiffness, gravel friction angle, and diameter on the bending characteristics of the GESC. The maximum bending moment of the GESC under bending conditions occurs at the anchored end. The dividing line of tensile and compressive stresses on the gravel in the anchored end section after bending failure appears at a radius of 0.5 of the column above the section centerline. The geosynthetic sleeve exhibits good resistance to tensile stress. The dividing line between the tensile and compressive stresses is located at the centerline of the section. The mechanical properties of the encasements and gravel has a significant impact on bending characteristics of the GESC. Increasing the strength of the encasement and friction angle of the gravel may significantly improve the bending capacity of the GESC, whereas an increase in the stiffness of encasement and diameter of the column decreases the bending deformation of the GESC.
Behavior of Cofferdam Using Non-uniform Geotextile Mats on Soft-overlying-stiff Foundation
Authors: Wang Mingyuan , Zhang Zuguo , Zhou Mi
Published: May 2024

Non-uniform geotextile mats are employed as soft foundations in cofferdams. However, investigations on the influence of complicated geological conditions on the mechanical behavior of cofferdams are limited. We investigated the behavior of a cofferdam using non-uniform geotextile mats to explore the failure mechanism of non-uniform geotextile mats over a soft overlying stiff foundation and quantify its stability. The two typical failure modes, global and local failure modes, differed distinctly in the velocity field and sliding surface shape. Geometric factors may partially affect the failure mode, whereas a higher soil strength can enhance the stability of the cofferdam, especially when stiff soil is involved. The failure mechanisms of cofferdams using non-uniform geotextile mats on soft overlying stiff clay and a corresponding stability prediction method are proposed to guide the design of cofferdams using non-uniform geotextile mats.
Analytical model for electrokinetic remediation of contaminated soil
Authors: Ge Shangqi , Wang Ji-Peng , Zheng Lingwei , Wang Hengyu , Xie Xinyu
Published: May 2024

Electrokinetic remediation (EKR) is an effective approach to eliminate heavy metal contaminants from soil and pore water. However, only a few studies have been conducted on related analytical theory because of the complexity of transport processes and the lack of effective calculation methods. In this study, a novel analytical model is proposed to investigate the one-dimensional transport of heavy metal ions (HMIs), encompassing electro-osmosis, electro-migration, hydraulic osmosis, diffusion, adsorption, and thermal diffusion. A comprehensive analysis is conducted to study the effects of key parameters on the transport process. Several important insights are gained, e.g., an increase in the Soret coefficient accelerates the migration of HMIs. Meanwhile, an increase in both the electric potential gradient and the hydraulic gradient is beneficial for the remediation of contaminated soil, although the effect of the electric potential gradient is more significant.
Optimization of solidification/stabilization materials based on solid waste geopolymer
Authors: Fu Jun , Chen Yonggui , He Jianghong , Zhou Han , Liu Wenlian
Published: May 2024

With the development of mining economy and human society, heavy metal pollution incidents have gradually increased while a large amount of mine solid waste has been produced.Red mud (RM) and blast furnace slag (BFS) are common solid wastes in mines with excellent heavy metal adsorption properties. Optimization of geopolymer solidification/stabilization(S/S) materials based on these waste materials is a good way to reduce solid waste and cure heavy metal contaminated soil, and has outstanding environmental protection significance.In this study, RM and BFS were used as geopolymer raw materials, and sodium hydroxide was used as alkali activator to prepare lead nitrate contaminated soil with Pb content of 0.5%. Laboratory tests were conducted to explore the effects of alkali-solid ratio, BFS content on the mechanical strength, toxic leaching characteristics and pH of geopolymer S/S lead contaminated soil. The optimal ratio of geopolymer is obtained. The results show that the S/S soil cured with RM and BFS geopolymer has good mechanical properties and heavy metal adsorption properties, and it has certain scientific research value and utilization prospect for the remediation of Pb contaminated soil.
Analytical investigations on thermomechanical behavior of energy pile groups resting on stiff soil strata
Authors: Fang J , Feng S , Zhao Y , Chen H , Zhou X
Published: May 2024

Energy piles are increasingly being exploited worldwide because of their dual role of exchanging heat with the ground and providing structural support for buildings. Despite the existing studies, simplified but reasonable methods for estimating the vertical displacement of end-bearing energy pile groups subjected to thermal loads are lacking. To address this challenge, an analytical approach was proposed to analyze the thermomechanical behavior of energy pile groups bearing stiff soil strata. To consider the reduction in soil displacement caused by the presence of a bearing layer, an approximate method where the energy piles comprising solid and mirror-image elements was introduced. The proposed approach was implemented using a self-developed program and validated against the results of existing numerical studies. The results indicated that the thermally induced displacement interaction between the predominant end-bearing piles was more pronounced than that between the floating piles. The displacement interaction decreases with decreasing shaft and base soil stiffness, increasing pile spacing, and decreasing pile slenderness ratio. In addition, a simplified method for estimating the displacement of energy pile groups resting on stiff soil strata was established by superimposing the interaction factor.
Research on high-pressure adsorption of supercritical CO2 and the characterization of coal structure change in anthracite
Authors: Niu D , Liang W G , Wang J M , Chen Y D , Yan W L
Published: May 2024

CO2-Enhanced Coal Bed Methane ( CO2-ECBM) Technology has been widely used in deep coalbed methane (DCBM) extraction and CO2 sequestration. CO2 is in the supercritical state ( ScC - O2 ) in deep coal seam reservoir, and has mechanical, physical and chemical effects on the coal body, making understanding ScCO2 adsorption crucial. Based on the self-developed supercritical isothermal adsorption device, ScCO2 high-pressure adsorption experiments were carried out in anthracite. Besides, using multiple characterisation methods to analyse the changes in microstructures of coal before and after ScCO2 adsorption and reveal the mechanism of processing. The results indicate that an obvious mutation zone in adsorption during high-pressure conditions is carried out, with the minimal adsorption capacity in the mutation zone; 2) The effect of ScCO2 on the microstructure of the coal mainly focuses on the micropores and mesopores (below 50 nm ), resulting in an improved coal adsorption capacity; 3)Providing three assessment indexes of potential of DCBM resource exploitation and CO2 sequestration includes the buried depth, porosity and fracture permeability. The above research outcomes provide important theoretical foundation for the development of DCBM resources, assessment of CO2 sequestration potential and engineering application.
Numerical analysis of failure mechanism and stability of reinforced embankment with DCM soft soil composite foundation
Authors: Ma X F , Ma C Y , Lin Y G , Tang G H , Wang Z H
Published: May 2024

The deep cement mixing (DCM) method has been widely used in offshore geotechnical engineering. At present, the reinforcement form of pile has been researched widely, but there is a lack of understanding of the failure mode of DCM pile composite foundation reinforcement for bank slopes. In this paper, a series of unconfined compression tests was conducted to obtain necessary numerical analysis parameters. A series of study on the failure mechanism and stability control of DCM pile composite foundation reinforcement bank slope has been conducted through numerical analysis. The results of numerical analysis indicate that under different reinforcement conditions, there exists an optimal reinforcement depth, and the safety coefficient will gradually stabilize at 1.45; The bending moment of the piles under the bank slope the bending moment of the pile body under the road surface Under different overloads. The maximum bending moment of the pile body is located near one-third of the pile body, and the maximum bending moment of the pile body is located between the shoulder and foot of the slope.
Mechanical responses of shallowly buried pipelines to adjacent deep excavations considering heavy rainfall influence
Authors: Chao Hui , Jiang Xiao-Tian , Tan Yong , Liu Jun-Cheng
Published: May 2024

Climate change has resulted in a high global incidence of heavy rainfall, severely damaging the urban infrastructure. The analytical method used to predict the mechanical response of pipelines under the influence of rainfall influence could serve as a valuable design basis in the preliminary stage. This study developed an analytical solution based on the stratified Green-Ampt model and displacement-controlled two-stage method. The first stage evaluates the greenfield soil displacement at pipeline elevation by employing the Mindlin solution and considering the superposed effects of excavation (unloading) and rainfall infiltration. The second stage predicts the mechanical responses of the pipeline by simplifying the pipeline–soil interaction into a continuous Euler–Bernoulli beam resting on a Winkler foundation model. The analytical solution was calculated using the finite difference method and verified against a published study. Finally, parametric studies were conducted to investigate the rainfall– excavation–pipeline interaction, including the rainfall intensity and duration, maximum lateral wall deflection, and pipeline location. The results showed that a 48-8-mm/h rainfall increased the maximum displacement and maximum bending moment of the pipeline by 6.54% and 7.93%, respectively. The prediction results provide practical guidance for designing deep excavations adjacent to pipelines buried under heavy rainfall conditions.
Numerical analysis of the surrounding responses induced by an irregular excavation in soft soil
Authors: Guo Jian , Liu Guobin , Xu Lei
Published: May 2024

This study focuses on an “X”-shaped irregular excavation in Shanghai, presenting a detailed numerical analysis of the impact of the excavation on the surrounding area and the deflection of the retaining wall. By comparing computational outcomes with onsite observations, the research delves into the interaction between the excavation process and pre-existing underground structures within soft clay environments. The present findings reveal that proximate subsurface structures can mitigate retaining wall deflection and ground settlement by up to 30% within a distance ranging from 0.65 He
to 1.0 He
(He
denotes the excavation depth). Furthermore, the intersection angle between the excavation site and the existing underground infrastructure significantly affects the excavation’s dynamics. Within areas influenced by these underground structures, the observed retaining wall deflection and ground subsidence were approximately 15-20% less compared to regions without such constraints.
Effect of flexural deformation on the bearing capacity of assembled H-shaped steel strut: A case study
Authors: Bing Xu Xiao , Huai Liang Yi , Yuan Wang Ming , Hu Qi , Jian Fang Hua
Published: May 2024

Abnormal flexural deformation was found in one assembled H-shaped steel strut (AHSS) of an excavation project. In order to assess the effect of flexural deformation on its bearing capacity, a field axial loading test was carried out before the dismantling of the AHSS. It was found that, due to the weak region around the loading component, the horizontal and vertical displacements were larger for the monitoring points closer to the loading component. The horizontal displacements of points H3 ~ H7 all exceeded the required limit value, and the maximum descent of each monitoring point was smaller than the required limit value. Steel columns showed negligible contribution to the restrict of the horizontal displacement but relatively good vertical support of the AHSS. As compared to the condition considering normal deformation, the safety redundancies of the AHSS were all smaller when considering the abnormal deformations. The mechanism of the flexural deformation was discussed, and suggestions for avoiding such abnormal flexural deformation were given.
Similarity Solutions for Spherical Cavity Expansion in Strain-Softening Soils and its Application in Cone Penetration Test
Authors: Liu Jiansheng , Zhao Cheng , Yu Songbo , Zhang Jiaqi , Huang Nenghao
Published: May 2024

The cavity expansion theory is commonly employed to predict the grouting pressure and cone penetration resistance. However, existing theoretical solutions for cohesive-frictional soils with dilation fail to simultaneously consider both the elastic deformation in the plastic zone and strain-softening behaviour of soils. To address this limitation, a similarity solution was derived for the expansion of spherical cavities from a zero initial radius with an initial confining pressure in strain-softening Mohr–Coulomb materials. The results demonstrate good agreement with previous theories, predicting an ultimate pressure higher than that obtained by neglecting elastic deformation in the plastic zone but lower than that calculated by neglecting softening characteristics. Moreover, several influential factors affecting the radius of the plastic zone and ultimate pressure were meticulously examined. On-site cone penetration test data and the theoretical results showed notable agreement. This indicates that the proposed solution exhibits a better conformance with the field data than do the previous solutions.
Large-diameter shield tunnel crossing closely to existing metro tunnels and a residential building: A case study
Authors: Su Z , Zhou C , Xie J , Huang X
Published: May 2024

In urban regions with multiple existing underground structures, the construction of a new shield tunnel can elicit intricate responses in soil-structure interactions. Here, we present an exhaustive case study of a large-diameter shield tunnel project in Shanghai, focusing on the section that closely crosses an existing metro tunnel and a residential building. Based on the in-situ data, the settlements of the ground, metro tunnel, and residual building induced by the tunneling were analyzed, and the correlations of their deformation mechanisms were discussed. The results indicate that the presence of a metro tunnel effectively mitigates ground movement. The settlement near the existing metro tunnel is significantly smaller than that in relatively remote areas. Additional displacements, settlements followed by heaves, were observed in the existing metro tunnels. Tunneling-induced settlement was also observed in the residential building, reaching a maximum of 8.92 mm facing the crossing side. Settlement along the tunneling direction decreased notably for residential buildings, primarily owing to the reinforcing effect of the existing metro tunnel. These findings underscore the importance of considering the soil-structure interaction within multiple existing underground structures during close tunnel crossings.
Grade prediction of rock burst based on PSO-RVM model
Authors: Kuang H W , Ai Z Y , Gu G L
Published: May 2024

A broad and accurate rock burst prediction model is crucial for preventing rock burst disasters in engineering. The relevance vector machine (RVM) algorithm based on the particle swarm optimization (PSO) is proposed for its prediction in this paper. The PSO is used to optimize the kernel parameter inside the RVM, while the RVM is applied to complete the prediction task. Firstly, according to a series of existing classification standards and theoretical research of rock burst, three impact indicators and four rock burst grades are summarized. Next, the PSO-RVM model is trained by the cross-validation method with main indicators as input and rock burst grades as output. Then, the universality and accuracy of the proposed model are verified by different engineering samples. Finally, a specific engineering case is used to verify the practicality of the model, and the prediction accuracy of rock burst grade is up to 100%.
Intelligence identification of tunnel surrounding rock mass grades using drilling jumbo data
Authors: Huang F , Zheng Y , Zhou X X , Tan B X
Published: May 2024

In drill-and-blast tunnels, the recorded data from fully computerized rock drilling jumbos can reflect the tunnel face rock mass conditions. An intelligent method based on real-time drilling data was developed herein to identify tunnel rock mass grades. First, the time series of 14 drilling parameters was processed using a Fourier transform, and the maximum amplitudes of each parameter were computed. Subsequently, the means, medians, and variances of the parameter amplitudes from different blast holes on the same tunnel face were satisfied to form the original feature set. Neighborhood component analysis was used to select the key rock mass condition features. From this feature selection (FS), the top five features were selected as the final feature set. Furthermore, using the selected features, a Gaussian Process Classification (GPC)-based model was established to predict rock mass grades. The proposed method captures both the drilling data information in the time dimension and the inherent connection of different blast hole data, making it advantageous. Using field construction data from Xiwuling Tunnel, the proposed FS-GPC model performance was evaluated. It achieved an accuracy of 90% in predicting rock mass grades. The proposed method can accurately and rapidly predict rock mass grades in drill-and-blast tunnels, optimizing engineering design and construction decisions.
Prediction of Airport Taxiway Settlement based on CNNBiLSTM-Attention
Authors: Li Yang , Qian Jiangu , Shi Zhenhao , Zhang Haihua
Published: May 2024

The accurate real-time prediction of complex time series in airport runway settlement is crucial. In order to achieve precise and reliable predictions of runway surface settlement, considering the nonlinear and time-dependent characteristics of settlement data under the coupling effects of dynamic loads, water levels, and other factors, a CNN-BiLSTM-Attention approach is proposed. This method first employs Convolutional Neural Networks (CNN) to extensively extract local temporal features from the input sequences. Subsequently, the extracted local temporal features are input to BiLSTM layers to learn the features of the sequences both in the forward and reverse directions. Finally, the output of the BiLSTM layers is fed into an attention mechanism layer. By computing attention weights, crucial information in the input sequences is weighted and added to enhance the model’s focus on key information. The final settlement prediction is then generated through a fully connected layer. To validate the proposed method, field settlement monitoring data from Runway L at Hangzhou Xiaoshan Airport are utilized as an engineering case study. The results indicate that the combined model captures local features of settlement sequences more effectively with a smaller dataset, achieving higher accuracy compared to a standalone BiLSTM model.
Reducing penetration resistance through bio-inspired head oscillation
Authors: Xue Zhenfeng , Zhao Chunfeng , Tao Junliang
Published: May 2024

Animals such as worm lizards can effectively bury themselves in the ground for survival. The burial behavior is realized due to the head oscillation of the reptiles using different strategies. It is hypothesized that the periodic penetration process generated from the anterior part of the animal reduces penetration resistance because it breaks the local force chains in the soil. In this paper, the three-dimensional discrete element method (DEM) modeling method was used to validate this hypothesis to investigate the interaction between a penetrator and the granular material at different scales. The penetrator was simplified as a three-body structure: an oscillating cone, a joint, and a cylindrical body. It was then penetrated through the soil sample vertically with different oscillation velocities. The results show that the oscillation movement can significantly reduce the penetration resistance force. Furthermore, the force chain network of the soil sample was investigated, and comparisons were made among cases, which shed light on the fundamental mechanism of the reduction effect.