bluuebunny/crossref_metadata_2025 huggingface dataset:
Field-monitoring and numerical investigation of a super-large-diameter shield tunnel undercrossing existing metro tunnels
Authors: Qin P , Su Z , Zhou C , Xie J , Huang X
Published: May 2024

The Beiheng Expressway in Shanghai was built using a super-large shield with a diameter of 15 m, and its construction impact on adjacent underground structures cannot be overlooked. This newly built tunnel undercrossed Shanghai Metro Line 18 with a minimum distance of 7.86 m. Noticeable additional movements induced by the crossing can be observed in both lines according to in-situ data, initially manifested as slight settlement followed by atypically pronounced heave. The maximum uplifts of the up and down lines reach 7.23 and 5.09 mm, respectively. Subsequently, a numerical study was conducted on this crossing case, and its effectiveness was verified using in-situ data. The results revealed- the soil-structure interactions during the crossing period. The displacement curves in the longitudinal direction of the metro tunnels exhibited asymmetry owing to the oblique crossing, with greater deformation occurring in the region that was crossed earlier than in the region crossed later. Significant heave was also observed for the newly built segmental linings and surrounding ground, indicating pronounced floating induced by large-diameter excavation, which in turn caused the existing metro lines to move upward simultaneously.
Longitudinal structural behavior of shield tunnel with large diameter and small curvature
Authors: Song Q Y , Zhang M X , Ding W J , Wu H M , Zhang Y C
Published: May 2024

The structural mechanism of a large-diameter curved tunnel is introduced in detail because no relevant calculation method is available. A longitudinal discontinuous contact model is established based on the newly built North Highway Tunnel in Shanghai, China. First, the load-spreading mechanism of circumferential joints was considered. Second, the distribution laws of the longitudinal internal force, settlement, and joint deformation of curved and straight tunnels under the same load were analyzed and compared. Finally, a model test is conducted to verify the effectiveness of the discontinuous contact model. The results indicated that with an increase in the radius of curvature, the maximum internal force and deformation decreased. The internal forces and deformations of straight and curved tunnels are quite different; therefore, the design method for a straight tunnel cannot be used in the design of curved tunnels. The overall and local deformations of the curved tunnel were affected by end displacement.
Study on anti-seepage mechanism of attapulgite-modified loess in Northwest China
Authors: Zhang Zhengrui , Zhang Lili , Ahad Aminipishro , Siti Jahara Matlan , Wang Hao
Published: May 2024

Loess is distributed widely in the arid areas in northwest China. Lanzhou city is located on the loess plateau, covered by a large area of deep collapsible Malan loess. Collapsible loess is a soft soil in engineering. It has a specific bearing capacity under dry conditions but will collapse after being immersed in water, which is unfavorable to engineering construction. This paper used the attapulgite abundant in the Zhangye City of Gansu Province as a modifier to improve the loess. The permeability test tested the permeability coefficient of the specimens under different dosages of attapulgite. The anti-permeability principle of attapulgite-modified loess was analyzed from the microscopic perspective by electron microscopy scanning (EMS) and nuclear magnetic resonance (NMR). The test results show that the permeability coefficient of attapulgite-modified loess decreases significantly compared with pure loess, but the permeability coefficient decreases gently when the content of attapulgite exceeds 10%. It was found that the anti-permeability mechanism of the modified loess was that the cohesive attapulgite particles filled the macropores of the loess particles, and the acicular attapulgite combined the loess particles to form a sheet structure, which reduced the porosity and permeability of the modified soil.
Numerical simulation of local scour around an inclined monopile in steady current
Authors: Liu Yihui , Huang Maosong , Jian
Published: May 2024

Local scour around the underwater supports of constructions would reduce the embedment depth and bearing capacity of support structures, seriously threatening the safety of the structures. Most existing investigations focused on the local scour of a vertical pile. However, in practical engineering, inclined piles are widely applied in underwater foundation structures to withstand lateral loads. The pile inclination can result in flow field alteration around the pile, thereby affecting the development of local scour. Consequently, a threedimensional numerical model of local scour around an inclined pile under steady current is established using the open-source CFD package OpenFOAM, in which the hydrodynamics are solved based on the Reynolds-averaged Navier-Stokes (RANS) equations together with k – ω SST turbulence closure in this model. It is then coupled with both bed load and suspended load transport descriptions, which drive the resultant morphology of the bed. The numerical model is verified by comparing it with the existing laboratory experiment. Discussions are carried out on the effects of inclination angles on the flow field alteration and the local scour depth variation.
Formulation and numerical realization of anisotropic permeability coefficient for fluid-solid coupling in underground engineering
Authors: Ding Wenqi , Li Fengshu , Shao Zhili , Qiao Yafei
Published: May 2024

Underground engineering soil functions as a typical porous medium wherein groundwater flow and alterations in pore water pressure can influence the medium’s porosity, thereby affecting soil permeability. Moreover, changes in porosity (volumetric strain) result in anisotropy in the permeability coefficient, complicating the accurate depiction of the entire fluid-solid coupling process using a uniform permeability coefficient. Fluid–solid coupling is achieved by establishing a connection between soil and fluid parameters in response to changes in the permeability coefficient during soil deformation. Considering the limitations of the deformation mode described by volumetric strain, this paper proposes different influencing factors of anisotropic principal strains (εx, εy
, and εz
) on the anisotropic permeability coefficient k
i, based on the Kozeny–Carman semi-empirical equation for the permeability of porous media. Additionally, a numerical simulation method for the fluid-solid interaction effect in underground engineering is implemented by incorporating variations in the permeability coefficient with strain, using a fish-parameterized programming language within the FLAC 3D software. The coupling effect of the seepage field with the strain-dependent permeability coefficient on the mechanical field is validated using a specific calculation example. This methodology presents a novel approach for expressing fluid-solid coupling processes.
Studying development trend of coastline change in China using CiteSpace
Authors: Song Y , Tian Z , Shao Y , Yue J , Cao L , Wang H , Xie C , Shan L , Li S , Tian D
Published: May 2024

The investigation of coastline alterations holds significant scientific and societal importance, particularly in guiding offshore engineering planning and design, as well as the economic development of coastal regions. In this study, we used CiteSpace software to examine relevant literature within the China National Knowledge Infrastructure database to explore the current status, hotspots, and frontiers of research on coastline change in China. Our findings revealed a consistent increase in the number of publications within this domain, with 1996 representing the first growth point in the number of publications on coastal changes. Since 2002, the number of publications has significantly increased owing to scientific and technological advancements and urban development. Research on coastal changes in China is primarily conducted in universities and research institutes, particularly at the Ocean University of China. However, research institutions and authors are widely dispersed, and the consistency between them is low. An apparent, balanced distribution phenomenon exists in this research field. Content related to keywords such as “coastline,” “coastal zone,” and “remote sensing” is the focus of research in this field. Remote sensing monitoring, big data analysis, and deep learning techniques are closely related to the study of coastline changes, representing the latest advancements in this field.
Evolution of mechanical properties of shield tunnels induced by water-soil gushing
Authors: Xie X C , Zhang D M , Zhou M L
Published: May 2024

Water-soil gushing in shield tunnels has been a major threat to the safety of tunnel structures. However, traditional numerical methods cannot reasonably simulate large soil deformation around the tunnel caused by the water-soil gushing. Therefore, it is difficult to reveal the evolution of the internal force and deformation of tunnel structures. In this paper, based on the two-phase Material Point Method, the numerical analysis method for the water-soil gushing was established to investigate the development of water-soil pressure acting on the tunnel surface, and then the evolution of the tunnel mechanical behaviours in the process of tunnel gushing was further studied. The results indicate that during the “rapid gushing stage”, the tunnel surface pressures around the leakage point decrease sharply, whereas those on the tunnel invert increase significantly. This gives rise to a significant increase in the shear force and bending moment of the tunnel lining, with increase rates of 114% and 82%, respectively. In addition, the axial and angular deformation of Joint No.2 near the leakage point increased significantly, which may lead to serious longitudinal joint dislocation or even concrete crushing. Thus, close attention to the joint deformation is required.
Study on the influence of water supply and drainage pipeline damage on urban silt ground collapse
Authors: Gu Zhanfei , Wei Hailong , Liu Zhikui , Guo Tong
Published: May 2024

Underground drainage pipelines play crucial roles in urban construction and development. Over time, these pipelines may incur damage and leakage due to aging and changes in surrounding loads. Ruptures and leaks in pipelines can lead to water seepage through cracks, resulting in erosion of surrounding soil layers and the formation of underground cavities. The loss of support in the soil above these cavities can lead to structural instability and eventual ground collapse. Such collapses can disrupt urban transportation systems, leading to significant social and economic consequences. This study specifically investigates ground collapse phenomena resulting from damage to drainage pipelines in silty soil within the Yellow River flood area in Zhengzhou City. By considering the influence of seepage velocity at the damaged pipeline section, the study differentiates between seepage erosion and scour erosion, conducting theoretical analyses and calculations for each scenario. The results show that ① when the surrounding area of the pipeline is damaged and the slow seepage rate causes a change in the critical groundwater level ΔH ≥ (Lσt
)/((1 – n)γw), the soil around the pipeline will be damaged by seep erosion; ② when the water flow velocity at the damaged area of the pipeline is reached V
0 = 2λ(γs
– γw
)a
2
B
2/(9μ(B
2 – b
2)), the water flow impacts the soil and causes erosion damage. The critical pressure within the pipeline can be derived from the stress state where the pipeline is damaged

P
1

=

ρ
2

[
2
λ
(

γ
s

−

γ
w

)

a
2

B
2

/
(
9
μ
(

B
2

−

b
2

)
)
]

; ③ the underground cavity formed by water flow erosion is assumed to be an “soil arch.” The stress analysis on it obtains the critical span of the “soil arch” when the “soil arch” is damaged 2b = [2c(H + h) + Kaγ(H + h)2 tan φ – P]/(H + h/3). This study provides a theoretical basis and technical support for the management of silty ground collapse in the Yellow River flood area.
Study on the susceptibility of debris flow disasters in southeast Tibet based on the information content model and random forest model
Authors: Gong Q Y , Zhao C
Published: May 2024

Linzhi, in southeast of the Tibetan Plateau, has high mountain and gorge terrain. Recently, with rapid changes in climate and fast development of engineering construction in Tibet, the fragile ecological environment in Linzhi has been further damaged, resulting in a sharp increase in debris flow disasters in the region. This poses a serious threat to local social and economic development and safety of lives and property. We divided the study area into multiple watershed units, and explored the reliability of the information content model (ICM), random forest model (RF), and their coupled model (ICM-RF) in the evaluation of debris flow disaster susceptibility. Through remote sensing interpretation, field investigations, and data collection, data on debris flow disasters and evaluation indicators in the study area were obtained. Using multicollinearity analysis, 16 evaluation indicators were selected from 7 major categories including topography, geological conditions, meteorological and hydrological conditions, ecological environment conditions, human engineering activities, seismic activities, and watershed characteristics; a debris flow disaster susceptibility evaluation index system was constructed. Prediction performance of the three models was tested using ROC curves. ICM-RF model had better prediction performance than single models, indicating its superiority for predicting debris flow disaster susceptibility.
Effects of Reverse Fault Dislocation Application Method for Tunnelling Through Active Faults
Authors: Huang Rui , Li Liqun , Chen Zhiyi
Published: May 2024

Active faults seriously threaten the structural integrity of mountain tunnels in seismic zones, and reverse faults are the most hazardous. A tunnel project in the western region was used as a reference to analyze the damage mechanism of tunnels under different modes of reverse fault displacement. The ABAQUS finite element analysis software was employed for the numerical simulation, and a quasi-static method was adopted to analyze the displacement and stress response patterns of the tunnel structure traversing the fault under three typical modes of reverse fault displacement. This led to deriving the tunnel structure’s longitudinal damage modes and impact zones based on reverse fault displacement. The study revealed that the damage modes of the tunnel under different fault displacement modes varied, which was reflected in the different degrees of shear and compression. Regardless of the fault displacement mode, the tunnel structure located within the fault fracture zone was severely damaged, with the most severe damage occurring at the interface between the fixed plate and the fault displacement section. Therefore, in the design, special attention should be paid to the displacement resistance performance of the dangerous sections of the tunnel. The research results provide significant reference and guidance for similar projects.
Assessment of geo-disaster in the snowmelt season considering climate changes
Authors: Kawamura S , Goto R , Yumiyama H , Shioda A
Published: May 2024

In this study, we reproduced avalanches and debris flow phenomena using the debris flow analysis tool, iRIC Morpho2DH, and laboratory-test apparatus. In the laboratory tests, we reproduced aggregates of snow, water, and soil that form during avalanches and debris flows using a pot mill turntable. Consequently, the possibility of forming aggregates of snow, water, and soil during debris flow phenomena was analyzed. Evaluation of avalanche and debris flow phenomena during the snowmelt season was conducted by considering the characteristics of these aggregates. Based on the results, the validity of the analysis method for the Nozuka disaster in Japan was examined. Moreover, the risks associated with future avalanches and debris flow phenomena under changing climatic conditions were studied using the Policy Decision making for Future climate change (d4PDF) database.
Observation and Analysis of Micro- and Meso-structure of Soil in the Shear Zone of Guoyemoli Landslide in Zhouqu County
Authors: Bing-xu Chen , Qiang-qiang Miao , Qing-qing Zhu , Wan-zhi Cao , Ji-zhong Gan , Hao-xiang Guo
Published: May 2024

An X-ray diffraction mineral composition test was conducted on the shear zone soil of the Guoyemoli landslide in Zhouqu County to analyze the deformation and strength characteristics of the shear zone soil under different stress states. A scanning electron microscope and a stereo microscope were used to observe the microstructure of the shear surface of the shear zone soil, revealing the microstructure evolution characteristics of the shear zone soil sample. The findings of this study provide a data basis for slope stability and risk assessment from a micro perspective.
Damage Evolution and Energy Catastrophe Behavior during Quasi-static Loading Process of Rockburst
Authors: Luo Yinfeng , Zhao Cheng , Qian Yuan , Xing Jinquan , Zhou Biaohe
Published: May 2024

Rockburst pose a serious hazard to deep underground engineering. The damage evolution and energy transformation of rockburst under quasi-static load are the key to reveal the mechanism of rockburst. Based on the instability theory and stiffness theory, the burst rock and surrounding rock combination specimens are designed in this study. Then a constitutive model for simulating the whole process of rockburst is established by statistical damage of rock. The law of damage deformation and energy evolution during rockburst is revealed, and the key factors affecting rockburst intensity are analyzed. The results indicate that the damage mechanism of rockburst is related to the sudden change of damage before and after the peak stress of the burst rock, and the volume ratio of surrounding rock to burst rock. The evaluation index of rockburst proneness based on energy evolution can reflect the energy conversion and transmission relationship between the surrounding rock and burst rock in the combination system, which is of great significance for the evaluation of rockburst proneness.
Ground vibrations induced by high-speed trains moving on layered near-saturated ground using 2.5D FEM
Authors: Geng J L , Gao G Y , Shi W J , Zhang Q W
Published: May 2024

An improved 2.5-dimensional finite element model is developed to investigate ground vibrations induced by high-speed trains moving on layered near-saturated soil. The accuracy of the model is validated using a theoretical solution. The effects of the train speed, soil type, and saturation on the vibration acceleration, displacement, and excess pore pressure are evaluated by comparing soft- and hard-layered near-saturated and saturated soil models. The findings suggest that the effect of saturation on the ground vibration acceleration and displacement is minimal when the train speed is below the critical speed of the soil. The vibration acceleration, displacement, and excess pore pressure in the soft-layered soil are higher than those in harder soil. Compared to harder layered soil, saturation has a more prominent influence on vibration acceleration and displacement in softer soil, whereas its influence on excess pore pressure is low. The rebound of the excess pore pressure at the saturated soil interface is more pronounced than that at the near-saturated interface. The effect of saturation on excess pore pressure is independent of the train speed.
Performance analysis of various numerical methods for predicting monopile response under machine induced vibration
Authors: Tankra S K , Desuri N P , Biswas S , Roy S
Published: May 2024

In this study, we verify the accuracy of the results obtained using two different numerical methods to simulate a pile-supported machine foundation under vertical vibration. To achieve this, finite element and finite difference methods, available as PLAXIS 3D and FLAC 3D, respectively, are selected for the study. A model consisting of a monopile with a diameter of 0.166 m and a length of 5.8 m is modelled to support the vibratory load induced by the rotary machine. A linear elastic model is used for the pile material and Mohr-Coulomb failure criterion is used for the soil. An analysis is performed to determine the frequency-versus-amplitude response of the monopile subjected to rotary-machine-induced vertical vibrations with different dynamic load intensities (0.735, 1.448, 2.117, and 2.721 Nm). The results obtained from both numerical analyses are compared with the experimental results available in the literature. Both numerical methods effectively simulate the nonlinear behavior of the soil-pile system, as observed in the experimental results. Based on the results, it is deduced that the finite element method simulated more harmonious results than the finite difference method compared with the experimental results, with more computational efficiency.
Further development of distinct lattice spring model with Finn model for liquefaction analysis
Authors: Li Zhe , Shoaib Muhammad , Wei Xin-Dong , Zhao Gao-Feng
Published: May 2024

The hazards associated with sand liquefaction induced by dynamic events are significant. The study of the dynamic stability in hydraulic structures presents an interdisciplinary challenge encompassing both geotechnical engineering and engineering seismology. This study was based on an actual hydraulic engineering project. To effectively predict changes in pore pressure caused by earthquakes, we integrated the Finn constitutive equations into a distinct lattice spring model (DLSM). In this study, the code was customized to accommodate multiple materials simultaneously participating in the calculations, thus simplifying the solution to complex engineering problems. Initially, we validated the DLSM’s liquefaction equation by comparing it with the finite difference method. Subsequently, we conducted a comparative analysis of liquefaction in an engineering project of sluice using the enhanced DLSM. Our analysis indicates that untreated sand has a severe risk of trending toward liquefaction, presenting a hazard to hydraulic engineering. The incorporation of a gridded concrete framework significantly mitigated the seismic-induced pore pressure accumulation and irreversible deformations caused by vibrations. A comparative study showed that concrete retaining walls with concrete supports are more effective at reducing liquefaction hazards and minimizing irreversible deformations in engineering structures.
Seismic damage analysis of shallow buried subway station in clayey sand soil under mainshock-aftershock earthquakes
Authors: Zhang Zhong-Liang , Cui Zhen-Dong
Published: May 2024

During earthquake events, a mainshock may trigger a number of following aftershock earthquakes in a short time. Usually, structures will be damaged to a certain extent by the mainshock, and aftershocks can further exacerbate the damage to structures, making post-disaster rescue and rehabilitation extremely challenging. Yet, most of research on seismic performance of underground structures only considered the single mainshock, ignoring the effect of aftershocks. In this study, a nonlinear numerical model of the shallow buried shallow subway station in clayey sand soil under mainshock-aftershock sequences was constructed to replicate the damage evolution process of underground structures. A limited numerical sensitivity analysis was performed considering the influences of the magnitude of mainshock and aftershock intensity. The results indicate that the damage of subway station is closely related to the magnitude of mainshock intensity. The aftershocks might cause more serious incremental damage to underground structures and secondary displacement of the site, potentially lead to collapse of the subway station, when the mainshock magnitude is greater. With the superposition of the mainshock and aftershock, the relative horizontal displacement of the subway station could reach the inter-story drift limit value. Therefore, the aftershock should be taken into account for seismic safety design of shallow underground structures.
A prediction model for residual shear strength of liquefiable soil based on lateral spreading cases
Authors: Yang Yanxin , Lu Hua , Wu Di , Lin Ziyun , Zhan Xudong , Zhong Wencheng
Published: May 2024

The residual shear strength of liquefiable soil plays an important role in evaluating the displacement magnitude of lateral spreading when applying the Newmark sliding block method. Currently, the empirical model is a mainstream alternative method for estimating the residual shear strength. In this study, a database of well-documented lateral spreading cases is used to establish an exponential function for residual shear strength evaluation correlated with the vertical effective stress and normalized standard penetration test blow counts for liquefied soil. A comparative analysis with two other empirical models is conducted, and the lateral spreading of the Wildlife Site during the Superstition Hills earthquake in 1987 is estimated using the Newmark sliding block method. The model exhibits good performance for soil residual shear strength estimation in cases of liquefaction-induced lateral spreading. The average estimated value of the residual shear strength may be appropriate for deterministic analyses in engineering practice.
Comparison and study of different seismic calculation methods for underground stations in Shanghai
Authors: Xing Li Xin , Chen Hong
Published: May 2024

In terms of seismic design methods for subway stations in the Shanghai area, both national and local standards have presented several pseudo-static methods, including response displacement, response acceleration, equivalent earthquake acceleration, and equivalent inertial force methods. However, certain issues are encountered when these methods are applied to the seismic design of real subway projects. The load input and results obtained from different calculation methods differ from each other. To address such discrepancies and compare the diversity of different methods, this study performs a comparative analysis based on the project case of a ground station in Shanghai. The seismic design is conducted using five different calculation methods. By referring to the results of the dynamic time history analysis, the causes of errors in the calculation results of the displacement and internal force are analyzed. The applicability of the methods is comprehensively explored in terms of a calculation model, determination of the equivalent load, error in the results, and project application. The results show that the response acceleration method exhibits the least error compared to the dynamic time history method. Therefore, the response acceleration method is recommended as the preferred method for the seismic design of underground stations in Shanghai.
Study on creep characteristics and reduction coefficient of geomembrane under top pressure
Authors: Wu D , Yi Y , Wu J , Liang T , Li D
Published: May 2024

A new top-pressure creep test device was developed to simulate the stress conditions of geomembrane in a real working state. CBR puncture and top pressure creep tests under different load levels were conducted using this device to study the creep characteristics of the geomembrane at top pressure. The top pressure creep reduction coefficients under different load levels and design lives were calculated and compared with the regular tensile creep reduction coefficients. Quantitative relationships between the creep-reduction coefficient, design life, and failure strain were established to predict the top-pressure creep-reduction coefficient. The results indicated that the top pressure creep reduction coefficient was greater than that of regular tensile creep. The creep reduction coefficient changed minimally with an increase in the design life. The top pressure creep reduction coefficient remained stable with an increase in the top pressure area strain for different design lives. Based on the results, to improve the safety and durability of engineering structures, the top pressure creep reduction coefficient should be used in the design of geosynthetics affected by the top pressure.
Numerical assessment of geocell-reinforced pavement performance subjected to cyclic loading conditions
Authors: Banerjee S , Manna B , Shahu J T
Published: May 2024

A numerical analysis was conducted using PLAXIS 3D software on a geocell-reinforced pavement over a soft subgrade under cyclic loading conditions. This study illustrates surface deformation and vertical stress within the subgrade layer of a reinforced pavement. The accuracy of the FE model was confirmed by comparing the results ofthe present study with those reported in the literature. This study investigated the influence of various factors, such as different infill and subgrade materials inreinforced pavements, on the overall pavement performance. These findings were compared with those observed for conventional planar-reinforced pavements. For improved infill and subgrade materials, the total surface deformation of the reinforced section decreased by approximately 15%–40%. Compared with the improvement in subgrade properties, a significant reduction of approximately 10% was observed inthe pressure response at the subbase-subgrade interface when using improved infill material. Moreover, compared to the planar-reinforced pavement, the geocell-reinforcedpavement reduced vertical stress at the interface between the base and subgrade by approximately 26%.
Study on preparation and property of coir fiber reinforced epoxy resin composite geogrid
Authors: Li L , Chen J , Cao W , Zhang Q. , Wang J , Li H
Published: May 2024

Based on the development and application of green composite building materials, this study prepared a coir fiber reinforced epoxy resin composite grid using coir fiber as the reinforcement material. Through tensile tests of a multi rib grid, the effects of coir fiber content, length, and rib spacing on the composite grid were studied. The results showed that with increase in the coir fiber content, the tensile yield force first increased and then decreased, reaching the maximum value at coir fiber content of 1%. When the coir fiber content exceeded 1%, the tensile properties of the composite grid were lower than that of pure epoxy resin. With the increase in the coir fiber length, the tensile yield force of composite grid also first increased and then decreased. At a fiber length of 1 cm, the maximum tensile yield force was obtained, which was 34.33% higher than that of pure epoxy resin grid. Compared with the influence of fiber length and content on the composite grid, the influence of rib spacing on the composite grid was more obvious. At a rib spacing of 1 cm, the tensile yield force reached its maximum.
Feasibility study of geosynthetic vegetation substrate for hard-surface ecological restoration part 1: Development of designated vegetation
Authors: Wu J Y , Guo J , Qiu T , Chen L Y , Qin C R , Chu J , Zhou Y , Zou B , Xu Y
Published: May 2024

Current ecological restoration techniques often face challenges on steep and hard surfaces (e.g., concrete or rock surfaces) because of their reliance on soil as a vegetation substrate. Two geosynthetic-based ecological restoration techniques are proposed in which a geosynthetic material is used to replace the soil as a vegetation substrate on hard-surface slopes. In the first technique, vegetation is planted directly on a geosynthetic vegetation substrate (GVS), where the GVS provides water to the vegetation and room for the growth of vegetation roots. In the second technique, Hygrophila ringens is first planted on the GVS. This plant exhibits rapid growth initially and then dies after three months, creating a layer of humus over the GVS. Subsequently, herbaceous vegetation can grow over the GVS. The effectiveness of the GVS restoration technique was verified by conducting a one-year-long experimental study. During the experiment, vegetation such as Tall Fescue, Bermuda grass, bentgrass, Chinese holly, and Tifdwarf were grown on the GVS. Vegetation growth parameters such as blade length, biomass production, and species iteration were monitored with respect to the vegetation species and seeding density. The experimental results suggest that both ecological restoration techniques based on the GVS can successfully sustain vegetation on concrete slopes.
Numerical analysis of the working performance of ring combination reinforced retaining wall
Authors: Zhang M X , Zhong W T
Published: May 2024

In this study, a new combined reinforcement structure suitable for reinforced soil-retaining walls is proposed. FLAC 3D finite element software was used to establish three-dimensional numerical models of reinforced soil retaining walls with different forms of reinforcement, and the effects of reinforced rings on the mechanical and deformation characteristics of retaining walls, as well as the mechanism of the reinforced rings working with horizontal geogrids, were investigated. The test results verified the superiority of the ring combination-reinforced structure in bearing and deformation under the same loading conditions. Moreover, the ring combination-reinforced soil retaining wall exhibited a stronger ability to resist deformation than the horizontal-reinforced soil retaining wall.
Numerical simulation of heavy metal migration in stabilized soils under multi-field coupling
Authors: Hua Yang , Suna Hui-Yang , Zhoua Shi-ji , Xua Yang , Zhanga Qing , Dua Yan-jun
Published: May 2024

Heavy metal contamination of soils has become a global issue. In pursuit of a reference for the management of heavy metal pollution, numerical simulations were used here to investigate the migration pattern of heavy metals in soil under multi-field coupling of rainfall, temperature, and hydraulic conductivity. Models were built using TOUGHREACT, and measured and simulated values were compared with those of existing studies to verify the accuracy of the software in simulating coupled water vapor-thermal transport and rainfall infiltration. Taking Nanjing rainfall data as an example, the transport pattern of zinc in soil under multi-field coupling was explored. Although evaporation and rainwater infiltration were found to increase with the temperature, the effects of evaporation and temperature counteracted each other, resulting in a weak influence of temperature on heavy metal transport. The hydraulic conductivity of stabilized soil was the main factor controlling zinc migration, with the saturation and heavy metal concentration clouds of soil columns tending to stabilize when the hydraulic conductivity of solidified soil was under 1 × 10-11 m/s.
Potassium permanganate oxidation of low-permeability phenanthrene contaminated soil under fracturing conditions
Authors: Shi Fu-Jiang , Feng Shi-Jin
Published: May 2024

In situ chemical oxidation (ISCO) technology has limitations in the remediation of low-permeability polycyclic aromatic hydrocarbon (PAHs)-contaminated sites because of the difficulty in oxidant delivery. Horizontal fractures created by hydraulic fracturing provide convenient channels for rapid oxidant delivery. However, limited studies have focused on potassium permanganate (KMnO4) oxidation in low-permeability PAH-contaminated sites under fracturing conditions considering in situ hydrological environments. Therefore, this study aimed to explore the effect of KMnO4 concentration on the remediation efficiency (including the removal rate of phenanthrene (PHE), remediation time, and total oxygen demand (TOD)) of low-permeability PHE-contaminated soil through a one-dimensional penetration-oxidation test, and the effect of KMnO4 oxidation on the physicochemical properties of the soil through a series of laboratory experiments. The results showed that an increase in KMnO4 concentration shortened the remediation time and increased the removal rate of PHE and TOD from PHE-contaminated soil. The oxidation of KMnO4 resulted in an increase in the pH, oxidation-reduction potential, dissolved organic carbon, cation exchange capacity, specific surface area, and fine particle content of the soil, and a decrease in the total organic carbon of the soil, but did not alter the permeability of the soil.
Assessing changes in geotechnical properties of soil caused by oil contaminants
Authors: Ali Shamshad , Nie Zhihong , Ismail Abubakar Sadiq , Sohel Rana
Published: May 2024

Soil pollution seriously threatens the integrity of geotechnical soil properties, considerably altering physical and mechanical characteristics. Therefore, the geotechnical characteristics of contaminated soils should be studied. Samples used in this study were obtained from Peshawar, Khyber Pakhtunkhwa Province, Pakistan. Tests such as Atterberg limits, direct shear strength, sieving analysis, consolidation, and unconfined compression were conducted. The internal friction angle, cohesiveness, and shear strength of the soil decreased when oil pollution was introduced, probably owing to the lubricating effect of oil, which also causes a decrease in the dielectric constant. Surprisingly, in certain cases, bioremediation could reduce soil swelling, relieve pressure from swelling, and prevent soil settlement. Oil contamination resulted in decreased permeability and mechanical strength in the analyzed soil samples. Importantly, the effect of oil contamination on the shear strength parameters is not uniform and depends on the soil type. A thorough study is required because of the long-term consequences of oil contamination, particularly the long-term aging effects on geotechnical soil properties and behavior. Therefore, these results must be compared with those of the most recent tests. Furthermore, future research should consider the complex interplay between the functional groups inherent in soil solids and the injected contaminated oil.
Impact of Industrial Solid Waste on Soil Geotechnical Properties
Authors: Sohel Rana , Nie Zhihong , Ali Shamshad , Ismail Abubakar Sadiq
Published: May 2024

In this study, the issue of industrial solid waste-contaminated soil and its consequences on various geotechnical parameters is examined. Soil health and geotechnical properties are affected by the global discharge of pollutants from chemical industries, including water, air, oil, and solids. Herein, the specific issue of soil contamination in Peshawar, Pakistan, is discussed. The goals of this study included examining variations in the Atterberg limits, direct shear strength, sieving analysis, consolidation behavior, and unconfined compression strength in contaminated soil samples. The process entailed analyzing soil samples taken from polluted sites in a laboratory. In contrast to uncontaminated soil, the results showed that contaminated soil deviated from the standard grading and exhibited lower liquid and plastic limits, higher moisture content, and lower specific gravity. Interestingly, the unconfined compression strength of the polluted soil was higher, indicating complicated interactions between the contaminants. Overall, this study highlights the need to understand and efficiently mitigate such human impacts by highlighting the extensive alterations in soil properties caused by industrial waste pollution.
Experimental study on the dynamic strength characteristics of combined heavy metals contaminated soil with nZVI treatment
Authors: Zou Meng , Wei Jing , Chen Yong-Zhan , Dong Qingxi , Chen Keyu , Fan Chen
Published: May 2024

Nanoscale zero-valent iron (nZVI), a high-performance nanomaterial, can treat heavy metal contaminants and is extensively employed for in-situ treatment of groundwater and contaminated subsoil. However, there are few studies that indicate trends in the dynamic strength parameters of nZVI-treated soils to assess site safety. In this study, three heavy metal contaminants, Zn(II), Pb(II), and Ni(II), were selected to contaminate virgin soil. The heavy-metal-contaminated soil was treated with nZVI at two concentrations (a low dose and high dose of 0.5% and 2%, respectively) of the soil's dry mass. Analyses of particle size distribution revealed a consistent shift towards larger particles upon nZVI treatment, and the percentage of sand gradually increased. Heavy metal contamination decreased the liquid and plastic limits of the virgin soil, while those of the treated soil increased with nZVI content. The dynamic triaxial results showed significantly lower maximum dynamic shear modulus for MS, MS-LdN, and MS-HdN than for NS. The damping ratios of all samples showed an S-shaped trend. Thus, nZVI has the potential to create cemented structures and immobilize heavy metals. However, its effectiveness is significantly modulated by the initial water content of the soil. While the application of nZVI proves beneficial in immobilizing heavy metal contaminants, careful consideration is imperative under dynamic loading conditions.
Engineering properties of microcapsules self-healing geopolymer cutoff wall backfill under dry-wet cycles
Authors: Xue Qin-Pei , Chen Hong-Xin , Feng Shi-Jin
Published: May 2024

Vertical cutoff wall has been employed for decades to control groundwater flow and subsurface contaminant transport. Environmental stress fluctuations induced by alternating dry and wet conditions impair the permeability and durability of the cutoff wall, leading to the dispersion of contaminants. The objective of this study is to incorporate self-healing microcapsules into existing geopolymer cutoff wall backfill (GCWB) to form self-healing geopolymer cutoff wall backfill (SHGCWB) that hold promise for better durability and performance. The in-situ polymerization method was used to develop single-walled and double-walled microcapsules. The microcapsules use sodium silicate as the healing agent encapsulated in single-walled polyurethane (PU) and double-walled polyurethane/melamine-formaldehyde (PU/MF) microcapsules. The effect of microcapsules on the unconfined compressive strength (UCS) and hydraulic conductivity of SHGCWB were elaborated. The durability and hydraulic conductivity variation of SHGCWB in dry-wet cycle was thoroughly investigated by Scanning Electron Microscopy (SEM) test for understanding the self-healing mechanism. The overall performance demonstrated the significant potential of the use microcapsules as a self-healing approach for cutoff walls.
Water balance estimation for an ordinary solid waste sanitary landfill in Costa Rica
Authors: Baltodano-Goulding R , Poveda-Montoya A
Published: May 2024

To assess the necessity of treatment systems for leachate generated by ordinary solid waste deposited in a sanitary fill, accurate estimation of the leachate and gas amount produced during biodegradation process is essential. Climatic conditions at the site significantly influence leachate generation; therefore, accurate estimation of rainfall, temperature, solar radiation, and infiltration into the fill is imperative. In this study, we analyzed the water balance of the Miramar landfill in Costa Rica, assessed the amount of leachate produced using various methodologies, and then compared these findings with the field data to identify the best methodology for specific environmental conditions. To comprehensively analyze landfill behavior, as well as the leachate and gases generated from waste decomposition, determining the hydraulic properties of the materials inside the cells is necessary. These properties must consider variables such as the types of materials present at the site, age of the ordinary waste, and their densities. The hydraulic properties of the materials were obtained from various laboratory tests, which included determining the soil–water characteristic curve necessary for assessing unsaturated conditions in the solid waste. These properties are compared with the results of studies conducted in other landfills to validate the current methodology and the obtained results, which can be used for conducting studies on leachate generation or slope stability analysis for sanitary landfill slopes. The amount of leachate generated was estimated using the methodology proposed by Delgado A. (2018). Additionally, the Hydrologic Evaluation of Landfill Performance model (HELP V 4.0) was employed, demonstrating superior estimation compared to recorded field data. The HELP V 4.0 model facilitated the incorporation of different material layers and thicknesses, weather information at the site, slopes, and drainage conditions.
Heating test of a silty sand in a short cylinder with a vertical hydronic grouted heating pipe
Authors: Kaneza N , Shrestha S , Lei G , Yu X B
Published: May 2024

Ground heat exchangers (GHEs) consist of HDPE pipes embedded in the ground to exchange thermal energy with the surrounding soils. Vertical GHEs are backfilled with grout materials to seal the soil boreholes, which are critical to the heat transfer at the pipe and soil interface. In this study, a short vertical soil cylinder was developed to measure the heat transfer process at the soil and pipe interface. The soil test cylinder consists of a 30 cm tall acrylic cylinder with a vertical 2.5 cm diameter (ID) HDPE pipe at its center. A grout of 85% bentonite and 15% graphite was compacted at 36% moisture content around the HDPE with a 1.4 cm radial thickness. A silty sand was chosen as the testing soil and compacted into the cylinder at 9% moisture and a dry density of 1.26 g/cm3. Moisture, temperature, and heat flux sensors were installed along the radial direction to measure the heat transfer process. The HDPE pipe was connected to a temperature-controlled water bath for a heating source at the specified constant temperature. The heating test of the silty sand with and without grout was compared. The thermal contact resistance at the pipe-grout interface was determined. The results demonstrated the impact of thermal grout on the heat transfer of GHEs, and the findings will help improve its design.
Coupled thermal-gas-mechanical phase-field modeling for fracture initiation and propagation in the underground caverns for compressed air energy storage
Authors: Xu Y J , Xia C C , Zhou S W , He X H
Published: May 2024

With the aim of addressing the large-scale engineering fracture problems in an underground cavern for compressed air energy storage (CAES), in this study, a coupled thermal-gas-mechanical (TGM) phase-field modeling for simulating fracture initiation and propagation in the CAES caverns is proposed. This study also focuses on COMSOL Multiphysics strategy of the TGM phase-field fracture modeling. The temperature field, air seepage field, displacement field, initial geostress field, and phase field are fully coupled and solved in COMSOL. A circular preexisting fracture zone is generated and used to initialize the fracture propagation according to the newly specified history strain field. The results indicate that the proposed TGM phase-field modeling and the corresponding COMSOL implementation strategy can simulate the thermodynamic responses and fracture initiation and propagation well. The lateral pressure coefficient and gravitational stress field have a strong impact on the fracture patterns and critical pressure, inducing fractures.