bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of hole wall stability in saturated clay using undrained solution for cylindrical cavity contraction
Authors: Li Sheng , Lü Xilin
Published: May 2024

To investigate the stress state of soil during the instability of the hole wall (hole shrinkage) in saturated clay, the theory of cylindrical cavity contraction in an infinite medium is applied, utilizing the modified Cam-Clay (MCC) model. By employing intermediate variables, the issue of cylindrical cavity contraction is reformulated into a first-order ordinary differential equation in Lagrangian form, with three effective stress components and pore pressure as the unknowns. In MATLAB, the stress conditions at the elastoplastic boundary serve as the initial values for solving the initial value problem of the differential equation system. After determining the correlation between the stress distribution around the cavity and the diameter reduction ratio, the analysis proceeds to evaluate the internal support pressure required for stabilizing the hole wall according to various stability criteria. This pressure is then integrated into the hole wall stability coefficient formula within the soil pressure model, facilitating the evaluation of hole wall stability. The effectiveness and accuracy of the proposed semi-analytical elastic–plastic solutions were subsequently confirmed through comparison with finite element analysis results, underscoring its relevance for addressing hole wall stability challenges.
Analysis of Covered Pile on Multi-row Pile Quay
Authors: Gao J Y , Wang K F , Zhu Y
Published: May 2024

The multi-row pile quay wall is an innovative permanent structure comprising multiple piles, relieving slabs, flood control walls, and backfill sand. Although it additionally serves as a functional wharf, the research on multi-row pile quay walls remains insufficient. Considering the Changxing harbor Pool as a case study, this research develops a multi-row pile quay wall structure using the three-dimensional finite element software PLAXIS 3D. We investigated the effects of covered piles, pile row spacing, spacing between covered piles, and the stiffness of the front pile on the internal force and deformation of the structure. The findings indicated that the presence of the covered piles results in minimal overall displacement of the multi-row pile quay wall and reduces the bending moment in the front pile. Considering the site conditions and project costs, the sensitivity of different parameters to the retaining effect was evaluated in the order of the stiffness of the front pile > pile row spacing > spacing between the covered piles. Building on this, an optimized design scheme is proposed to reduce the bending moment in the front pile by 50% compared to the original scheme, thereby offering valuable insights for future engineering projects.
Probabilistic dislocation capacity model for mountain tunnel crossing strike–slip creeping fault
Authors: Xu Longjun , Zhu Jingzhou
Published: May 2024

Fault dislocations significantly affect the performances of cross–fault tunnels. However, there is a lack of rapid and accurate methods for estimating the maximum fault dislocation that tunnels can withstand (i.e., the dislocation capacity of tunnels). This study systematically investigates the dislocation capacity of circular tunnels crossing strike–slip creeping faults while considering uncertainties in the lining parameters, rock strength, and crossing angles. Through pseudostatic numerical simulations, the dislocation capacities of tunnels under various working conditions were determined, and a probabilistic dislocation capacity model was developed using a support vector machine. The proposed model can estimate the probability distribution of the dislocation capacity of a tunnel, with its median closely aligned with the numerical result. Another advantage lies in its direct correlation with the lining parameters, rock strength, and crossing angles. This facilitates a rapid assessment of the tunnel dislocation capacity based on existing parameters. The dislocation capacity and vulnerability curves of a case tunnel are estimated using our probabilistic model, which serves as a demonstration. The results demonstrate that the proposed model is convenient for engineering applications and can assist in the design and optimization of cross–fault tunnels.
A resilience optimization design model considering surcharge for large diameter shield tunnel
Authors: Zhang D M , Li H Y , Huang Z K , Gao J H , Yang G , Zhu M H
Published: May 2024

Large-diameter shield tunnels face challenges owing to the complex strata and surcharges. The robustness of ground disturbance during excavation and resilience during operation in the design model must be considered. This involves establishing a damage evolution law for existing shield tunnels after surcharging and proposing a resilience design method for the entire cycle. In this study, the design process was initiated by utilizing existing borehole survey information and incorporating stratum uncertainty. Subsequently, a ground surcharge was applied to evaluate the changes in the force and deformation at different design points after surcharging. A resilience assessment was conducted in accordance with the specified criteria, and the results indicated that a majority of the design points exhibited robustness within acceptable limits after the surcharge. The original excavation design demonstrated satisfactory initial performance in terms of robustness. However, the resilience after surcharging was suboptimal, exhibiting a value of only 0.65. To enhance the resilience, the design must modify the reinforcing rate to achieve a higher resilience state of 0.8. By considering both the robustness of the design and its resilience after surcharging, modifications can be made to align the design with real operational conditions, which may help improve the overall resilience.
Study on the evolution patterns of concrete lining’s physical and mechanical properties under sulfuric acid corrosion conditions
Authors: Xu Q , Wang H , Huang X
Published: May 2024

During operation, deep water storage and drainage tunnels may face sulfuric acid corrosion resulting from microbiologically induced chemical reactions. In this study, sulfuric acid corrosion experiments were performed on C60 concrete specimens with steel fiber volume ratios of 0% (plain) and 1% using a sulfuric acid solution with an initial pH of 1. For one-face corrosion, five faces of cubic concrete samples were coated with exposed resin, leaving only one face exposed to sulfuric acid. For all-face corrosion, all faces were exposed to sulfuric acid. Concrete corrosion under different loading conditions was compared by adding weights on top of the concrete. Rate of mass change variations and uniaxial compressive strength at various corrosion time points were monitored. The results indicated that after sulfuric acid corrosion, there was an increase in the mass but an overall decrease in the strength of the specimens. Compared with all-face corrosion, one-face corrosion led to a smaller increase in the mass of the concrete specimens and a more substantial decrease in strength, primarily because of the slower corrosion rate and reduced gypsum formation. Compared to plain concrete, steel fiber-reinforced concrete experienced a lower increase in the mass of the concrete specimens because the steel fibers obstructed sulfuric acid infiltration. However, there was significant corrosion of the steel fibers and surrounding concrete owing to accumulation of sulfuric acid around the former, resulting in a more substantial decrease in the uniaxial compressive strength of the steel fiber-reinforced concrete. With increasing load, the rate of change in the concrete mass initially decreased and then increased; this could be because increased loads densify the concrete, hindering sulfuric acid infiltration and promoting the development of microcracks within the concrete, thereby enhancing the effects of sulfuric acid corrosion.
Mechanical characterization of lining under three-dimensional complex load during shield posture adjustment
Authors: Yudong Wu , Wenqi Ding , Xiaoqing Chen
Published: May 2024

The shield tunneling method is widely used in urban underpass construction. However, research on the mechanical characteristics of segments during construction is insufficient. Throughout the shield tunneling construction process, segments undergo a diverse range of loads, and their modes become complex. During the adjustment of the posture of the shield machine along a curved path, segments must withstand three-dimensional uneven loads from the shield tail brush and extrusion of the shield shell, in addition to conventional loads. Thus, this study delves into the mechanical characterization of the lining during shield posture adjustment. First, three-dimensional refined models of the longitudinal and circumferential joints were established to investigate their bending and shear mechanical properties. Using the joint and shield tail brush stiffness models, a nonlinear spring-connector-shell model was developed for the mechanical analysis of segments during posture adjustment. Subsequently, a three-dimensional segment load model was formulated for the construction period. The segment response under the influence of different posture adjustments was examined using a numerical model of a tunnel subjected to a complex three-dimensional load. Furthermore, a multistage model of the segment response under various posture adjustments was established. This model serves as a valuable reference for engineering applications.
Framework for determining the safety distance of karst caves adjacent to tunnels
Authors: Ding M , Lin P
Published: May 2024

Karst caves pose safety issues for tunnels in karst areas. Karst caves at a certain distance from the tunnel must be treated fully to mitigate risks. A threshold of 3 m is typically adopted; caves within this threshold are fully treated, while those beyond are left untreated, regardless of the geological environment, cave features, tunnel design, operating conditions, etc. This poses risks to tunnel safety during construction and operation. This paper proposes a novel framework based on the aforementioned aspects to determine the treatment distance for caves from the perspective of uncertainty and risk. Geological conditions include the soil and rock type, weathering degree, underground water system, and pH. Karst caves primarily include the size, shape, distance, spatial distribution, density, and filling condition; the tunnel aspect refers to the tunnel diameter, construction method, design life, importance, lining, and tolerable criterion; and operation conditions refer to the vehicle speed, operation time, vehicle load, and maintenance. Herein, the parameters/indices for these aspects and methods to quantify their values are described. A decision-making process is illustrated to revive the mindset of risks in tunnel engineering. The proposed framework is effective for optimizing decision-making in karst cave treatment for tunnels in karst areas.
Research on construction and environmental impacts of a large-diameter pipe jacked along curve underwater
Authors: Zhen L , Wang J , Wang J , Hou S
Published: May 2024

The pipe jacking method is widely used in water supply and drainage, power tunnels, vehicle tunnel construction, and other fields. The main challenges include friction resistance, axis deviation, and environmental disturbance, especially when large-diameter pipes are jacked along the curve underwater. Based on a large-diameter pipe jacking project under Jinshan Lake, this paper records the settlement of surrounding structures, the jacking force, and the deviation in the axis and elevation during the jacking process. Furthermore, the factors affecting the monitoring data under different working conditions are studied, and the key points are concluded. The outcomes of the study will provide a reference and serve as a guidance for future related projects.
Multifidelity operator learning for predicting displacement fields of tunnel linings under external loads
Authors: Xu C , Liu Z , Cao B T , Meschke G , Liu X
Published: May 2024

In practical tunnel projects, the deformation of tunnel linings affects the service performance and structural reliability of tunnels. However, currently, several monitoring points must be installed to represent the specific deformation patterns of tunnel linings accurately, incurring high labor and financial costs. In recent years, the rapid development of artificial intelligence has provided potential solutions to this issue. To solve the aforementioned problem, this study proposed a multifidelity DeepONet framework, which comprised two neural networks. The first low-fidelity network was trained with data provided by a macro-level numerical model validated by experimental campaigns to learn the physical deformation patterns of tunnel linings. The second network was trained with limited high-fidelity monitoring data to learn the correlations between observations and numerical models. Even with very limited monitoring data, the proposed framework could still predict the mechanical behavior of tunnel linings under different loading scenarios. In this study, data collected from noncircular tunnel projects were used as case studies. The results demonstrated that the final output conformed to the deformation pattern obtained with the numerical simulations and was consistent with the actual measurements, achieving seamless fusion of the experimental campaigns and numerical models.
A tentative study on the effect of tunnel width on the maximum temperature under the ceiling in tunnel fires
Authors: Wang A M , Yan Z G
Published: May 2024

Maximum gas temperature under the ceiling in tunnel fires has been studied experimentally and numerically. Full scale burning test in tunnel with length 100 is carried out. Three different pool fires with approximate maximum heat release rate of 0.6, 1.0 and 5MW were set up. The smoke temperature is collected by the Fiber-optic Bragg grating system. CFD simulations were carried out to study the effect of tunnel width on the maximum temperature. By analyzing the experimental and numerical simulation results, a critical point of ratio B/H and two stages concerning the varying of B/H are proposed to clarify the influence of tunnel width, meanwhile we conclude that it is interdependent between the ratio of H/B and the ventilation velocity when discussing the maximum gas temperature in tunnel fires.
Comparative evaluations of building impact assessment due to adjacent tunneling
Authors: Ekaksorn N , Chayaroon A , Phutthananon C , Jongpradist P
Published: May 2024

In dense urban areas, tunneling can potentially lead to structural damage or compromise the integrity of nearby buildings, thus necessitating a thorough evaluation of its impact during the design phase. Various engineering methods exist to estimate building responses to adjacent tunneling, each varying in complexity. These methods yield different outcomes, such as settlement magnitude and behavior. This study examines pile settlements, differential pile settlement, and angular distortion of a building through three distinct analysis methods. These involve two-step methods of soil-structure interaction of a building and tunneling from (1) the corresponding greenfield ground, (2) piles embedded in the ground, and (3) piles under loading. The results were then compared and discussed. Based on the obtained results, the method for considering piles under loading can be regarded an effective method for providing a conservative evaluation.
Simplified nonlinear model and 3D printing model experiment verification of longitudinal joints of shield tunnel segments
Authors: Fu Yanbin , Zhu Junzhou , Zhang Yanlong , Chen Xiangsheng , Hu Yu , Gendi Yelv , Wu Ze , Li Xiaoping
Published: May 2024

The segment joints represent vulnerable and core-bearing areas within shield tunnel structures. Their flexural stiffness, starting from the contact surface of longitudinal joints to the bolt hole, exhibits continuous changes under bending loads, typically demonstrating nonlinear mechanical characteristics. This study investigates the influence of joint contact surfaces on flexural stiffness, extending from the joint contact surface to damaged concrete in the compressed zone. A new simplified model for the variable nonlinear stiffness of longitudinal segment joints in shield tunnels is proposed, considering the flexural stiffness of the joint contact surface and the width of the damaged concrete zone in the segment ring while simulating the flexural stiffness decay induced by the opening of segment joints. Based on the minimum potential energy principle, a design calculation method for joint flexural stiffness is derived, establishing the nonlinear bending stiffness coupling relationship between the segment and the joint. Through similarity theory, 3D printing technology, and indoor loading tests, the theoretical model's accuracy regarding tunnel segment joints is verified. This theoretical model provides a basis for designing and assessing the performance of tunnel-segment joints.
Strength degradation of foamed cement paste under sulfate attack
Authors: Ye G , Chen Y , Zhang Z , Shen H , Chen Y
Published: May 2024

Foamed cement paste is increasingly being applied in the construction of road embankments, bridge abutments, slope treatments, and pipeline backfilling. Constructed foamed cement paste may suffer from sulfate attacks in certain environments, such as offshore regions and salty soil areas. However, the long-term performance of foamed cement paste under such circumstances remains unclear. In this study, laboratory tests are conducted to evaluate the strength deterioration of foamed cement paste after erosion by sulfate attack. Factors influencing the density of the foamed cement paste, concentration of the sulfate solution, and cation type (i.e., Na+ and Mg2+) are considered. The results indicate that the strength of the foamed cement paste decreases with increasing immersion time. The Na2SO4 solution has a more severe erosion effect than the MgSO4 solution when other conditions remain constant. Finally, X-ray diffraction is conducted to identify the phase of the crystalline material in the specimen. This study will be beneficial in the application of foamed cement paste in regions with salt-rich soils.
Numerical investigation of the effect on the erosion effect under the action of solitary wave
Authors: Yan Heqing , Qian Jiangu
Published: May 2024

Local scour is a factor that cannot be ignored in hydraulic engineering, which seriously threatens the safety of hydraulic structures. There is a lack of consideration of periodic hydraulic conditions in the existing research on erosion. In this paper, the application range of various wave theories is analysed, and the isolated wave which is suitable for offshore is selected to study. Based on the Euler multiphase flow model, it is developed by using the user definition, and the generation and extinction modules are introduced to simulate the isolated waves, and then the cyclic waves in the offshore area are simulated by the superposition of multiple isolated waves. The hydrodynamic characteristics of isolated waves, including the pressure distribution of isolated waves, are analysed.
Evaluation of infiltration testing methods for design of stormwater drywell systems
Authors: Kamalzare M , Kindred S , Sharbat A
Published: May 2024

The current infiltration testing and drywell design methods do not always provide accurate estimates of the capacity of production-scale dry wells. In numerous cases, the predicted capacities appear to be considerably lower than the actual drywell capacity, resulting in more drywells than required and significantly higher construction and long-term maintenance costs. In other cases, the uncertainty in the measurements results in the predicted capacities being higher than the actual drywell capacity, resulting in fewer drywells being required. In this study, we discuss the reasons for these inaccurate predictions of drywell performance using current methods, as well as the results of recent studies to develop improved methods for predicting the capacity of stormwater infiltration drywells. These studies, funded by the United States Environmental Protection Agency (EPA) and the Los Angeles County Safe Clean Water Program (SCW), include numerical simulations and field studies in California. These test methods rely on steady-state infiltration tests in small-diameter boreholes and produce an estimate of the saturated hydraulic conductivity, which can be used to reliably predict the performance of large-diameter drywells. The methods were validated by testing small- and large-diameter test wells in close proximity using three different drilling methods. The results of this study describe the design and conduct of a borehole infiltration test that accurately represents drywell performance. Furthermore, based on a combination of numerical simulations and field studies, reduction factors were developed to account for test uncertainty, test duration, analytical error, field variability, potential for groundwater mounding, and clogging.
Evaluation of key parameters in rainfall-induced shallow landslide analysis: Are Di Village Case
Authors: Parapan A , Chao K C , Saowiang K , Soralump S , Nontapot T
Published: May 2024

Are Di Village experienced a devastating landslide in September 2020. This research utilized the transient rainfall infiltration and a grid-based regional slope stability model (TRIGRS) to assess the causes of slope instability. Input parameters such as soil properties, rainfall data, slope geometry, and soil thickness were integrated into the analysis. The models were validated using landslide scars from the event. The analysis results indicate that soil thickness significantly influences landslide susceptibility. In this study, the empirical equation utilized to estimate soil thickness considered the influence of topography on the distribution of soil thickness. The results calculated from TRIGRS showed that the model with a maximum soil thickness input of 3.5 m produced the most reliable landslide susceptibility map with an %LSclass of 40% and %LRclass of 65%.
Behavior of soil slopes reinforced with composite-structural piles
Authors: Xiang Yang , Liu Sujia , Zhang Ga
Published: May 2024

Slope stability is a key problem in geotechnical engineering, often addressed through reinforcement methods, such as reinforced concrete piles. However, they have limitations, including high costs and underutilization of steel and concrete properties. This study proposes a new type of composite-structural pile, combining two types of materials with different mechanical behaviors. Centrifuge model tests were performed to explore the deformation and failure behavior of slopes reinforced with the composite-structural pile under vertical loading conditions. The strains and soil pressure of the composite-structural pile were measured to analyze its stress characteristics. The composite-reinforced slope exhibited progressive failure from the top to the toe under vertical loading conditions, featuring a curved, discontinuous slip surface. The slope deformation increased with increasing load and developed to deformation localization. A clear coupling effect was observed between slope deformation localization and local failure. Finite element analysis was performed to evaluate the mechanical characteristics of the composite-structural pile under bending conditions. The strain distribution on the cross-section of the pile was linear for different material parameters. Based on these findings, a method for calculating the stress and strain of composite-structural piles was developed. Centrifuge model tests validated the reliability of the proposed method.
Experimental investigation on the characteristics of seepage failure of landslide dams with strongly permeable zones
Authors: Liu Zhaozhao , Chen Qun , Chen Chen , Li Xing , Zhao Changhong
Published: May 2024

Landslide dams are formed by river blockages caused by landslides or other slope instability bodies. They exhibit loose structure, poor stability and strong permeability. Large water head caused by water-level increase can trigger seepage deformation of soil and influence the stability of landslide dams, possibly leading to dam breach and catastrophic damage. Various landslide dam structures also result in differences in seepage characteristics. In this study, multiple physical model tests for seepage failure of landslide dams with strongly permeable zones were designed. The influence of the location and gradation of the strongly permeable zones on the seepage of landslide dams was studied. The characteristics and modes of seepage failure of landslide dams with strongly permeable zones were analysed. The experimental results showed that the cyclic evolution failure of piping and downstream slope collapse was an essential failure mode for the seepage-induced failure of landslide dams with strongly permeable zones. Compared with the strongly permeable zone at the bottom of a landslide dam, the piping caused by seepage evidently promoted the slope erosion of the dam with the strongly permeable zone in the middle. As the permeability coefficient of strongly permeable zones increased, piping was faster and easier to form, and piping failure, slope erosion, and slope collapse were more severe. The seepage failure of landslide dams mainly included the emergence of seepage water, piping, slope erosion, and downstream slope collapse. Piping was caused by the erosion and migration of some fine particles of soil in seepage channels in the dam. When the flow drag force could overcome the resistance force among the soil particles, some fine particles and even large particles on the downstream slope surface were continuously eroded. This study provides new insights into the evolution process and breach mechanisms for the seepage-induced failure of landslide dams with strongly permeable zones.
Dynamic change of a typical surging glacier in the Qinghai tibet plateau based on satellite remote sensing
Authors: Yuan Xiaohan , Baima Jizong , Qiao Gang , Song Xiaoyu
Published: May 2024

With global climate change, some mountain glaciers in the Qinghai–Tibet Plateau region are experiencing rapid melting, retreating, and acceleration. Surge-type glaciers are important objects for glacier dynamics research in this region, as sudden surge may threaten human activities and lives. This study focuses on the Shahrek Glacier. Based on multi-source remote sensing images from 2000 to 2023, we generated long-term ice flow velocity maps of the glacier using image template matching technology. Together with its terminus position over this period, the surge dynamics of Shahrek Glacier were analyzed. The glacier surge commenced in September 2016 and terminated in November 2018, reaching a maximum ice velocity of almost 1,200 m/a, which is 9–10 times its ice velocity in the quiescent phase. A substantial change in the magnitude of the ice flow before and after the onset of the Shahrek Glacier surge was observed; the surge comprised five main phases: pre-surge stable, accelerated, surge, decelerated, and stabilized periods. The Shahrek Glacier was retreating from the position of the glacier-terminal ablation zone prior to the onset of leapfrogging. We analyzed the relationship between Shahrek Glacier dynamics and climate and the surge mechanism surge, considering data from meteorological stations in neighboring regions.
Application of UAV 3D Point Cloud Data in Highway Slope Disaster Investigation
Authors: Xin Yan , Feng Hu , Yiqiang Yu , Wei Zhan , Dingyi Zhang , Zhi Hu
Published: May 2024

The safety and stability of highway slopes have always been critical concerns in highway management and maintenance. However, mountain road slopes, characterized by their small scale, large quantity, and complex geological conditions, pose challenges for effective deformation detection, putting significant pressure on highway management and maintenance. To address the difficulty in identifying hidden hazards of highway slopes in mountainous areas, this study proposes the use of unmanned aerial vehicle (UAV) closed-range photogrammetry technology for slope inspection. The M3C2 (Multiscale Model-to-Model Cloud Comparison) algorithm is employed to accurately calculate differences in multi-phase three-dimensional point cloud data, enabling the detection of overall slope deformation with centimeter-level precision. Field verification conducted on a highway slope in Qingtian County, Zhejiang Province, demonstrated the applicability of UAV 3D point cloud data in investigating highway slope hazards, thereby enhancing inspection efficiency and quality and providing technical support for highway management and maintenance.
Estimating sliding displacement of slopes induced by earthquake sequences based on the finite element method
Authors: Zhang C Y , Wu Q , Li D Q , Du W
Published: May 2024

After shocks trigger or worsen landslides by exacerbating damage to slopes. In this study, slope sliding displacements induced by seismic sequences were calculated. The combined effects of mainshocks and aftershocks on slope sliding were examined in this study using 273 ground motion records from real seismic sequences. A three-layer clayey slope was modeled in OpenSees. The ground motions were input for dynamic analysis to calculate the corresponding sliding displacements. More than 20% of the seismic sequences caused slope instability. The Arias intensity (Ia) of the mainshock had the strongest correlation with sliding displacements. The strength reduction technique was used for the pseudo-static stability analysis of the slope whose yield acceleration (ky
) value was 0.23g. The Newmark method computed smaller displacements compared to the finite element method which calculated the dynamic behavior of the slope more accurately when Ts/Tm > 0.1. The Ia of the mainshock was the optimal parameter. An empirical model based on finite element numerical analysis was proposed for predicting slope sliding displacements induced by seismic sequences. The predictive model, unlike the traditional rigid sliding block method, prevented some unrealistic assumptions. The proposed model was more conservative than numerical algorithm-based predictive models that compute only the mainshock effect.
Application of microtremor H/V spectral ratio method in determining characteristic parameters of typical laterite sites
Authors: Zhou YX , Li YQ , Xu Y , Liu XF , Chen B
Published: May 2024

Microtremor signals contain rich geophysical information, and the application of microtremor measurements in determining site characteristic parameters is increasingly valued because of their advantages of simple operation, environmental friendliness, and low cost. In this study, systematic microtremor measurements were conducted at a typical laterite site. The microtremor measurement data were processed with different combinations of horizontal components using the H/V spectral ratio method(H: Horizontal frequency domain signal of the microtremor; V: Vertical frequency domain signal of the microtremor). to take the HVSR curve. The period corresponding to the peak of the HVSR curve was considered to be the predominant period of the site, the site classifications were determined, and geotechnical types were divided. This study indicates that the microtremor H/V spectral ratio method is highly consistent with the results of borehole exploration for determining site classifications and dividing geotechnical types. Moreover, using the combination of vectors sum of East-West direction and North-South direction as horizontal components in the microtremor H/V spectral ratio method can more easily and accurately determine the site-predominant period.
Evaluation of variability of shear wave velocity in India
Authors: Al-Ajamee Mohammed
Published: May 2024

The shear wave velocity is a significant component in seismic hazard studies. This involves standard practice in seismic hazard analysis through ground motion prediction equations (GMPEs), ground response analyses (GRAs), or the computation of amplification factors. In practice, the shear wave velocity may be obtained through invasive methods, noninvasive methods, transformation models, or correlation-based methods. Currently, the uncertainty component of shear wave velocity has either been overlooked or oversimplified. The aim was to quantify the range of variations in shear wave velocity across India. The database included data of reported shear wave velocities in 20 states collected from various project reports and publications. A brief review of the methods used to obtain the data is given, along with a systematic highlight of the range of uncertainties encountered and their statistics. Base-case profiles for response analyses are recommended, and their statistics are examined. These observations aid computation of amplification factors. The transformation uncertainties of the shear wave velocity and the standard penetration test (SPT) were examined. The outcomes of the research will guide reliable seismic hazard studies across countries. Furthermore, this study paves the way for future development toward addressing uncertainties in shear wave velocity and facilitates the use of reliability-based design procedures.
Shaking table model test for seismic response of soft soil site
Authors: Tang Y , Chen Q , Zhao Z , Hong N , Liu Y
Published: May 2024

Soil sites play a crucial role during earthquakes and serve as conduits for the transmission of seismic effects from the bedrock to urban structures. Analyzing the dynamic response of soil sites to seismic waves is crucial as it presents deeper insights into earthquake damage mechanisms. In this study, we prepared a mixture of sawdust and medium sand with a 1:2.5 mass ratio to model soil samples from a soft soil site in Shanghai. The applicability of the scale-factor equation was verified using resonance column tests. A series of shaking table tests were conducted to simulate free-field site responses based on the dimensions, operating frequencies, and vibration modes of the shaking table at the State Key Laboratory of Disaster Reduction in Civil Engineering at Tongji University. Three different types of earthquake waves were selected as the input motions: TCU003 for far-field long-period seismic waves, TCU068 for near-field pulse-type seismic waves, and the El Centro earthquake wave. The Kramer frequency domain method was used to verify the transfer functions of the site seismic responses. Furthermore, discrepancies in the time–frequency distribution of the soft site responses influenced by various types of earthquake waves were assessed and analyzed. The seismic response characteristics of the soft soil sites under varying input intensities were also analyzed. The findings of this study present valuable reference data for the seismic zoning of soft-soil sites and facilitate the determination of seismic input parameters for engineering structures.
Permeability Prediction in Nonwoven Geotextiles Using Mathematical Modeling and Numerical Simulation
Authors: Li K. Y. , Tang X. W. , Chen W. L. , Wang T. Q. , Xiang Q. Q.
Published: May 2024

The vertical permeability coefficient is a pivotal hydraulic index of needle-punched nonwoven geotextiles. The accurate determination of the permeability coefficient is important for assessing engineering properties. This study employed mathematical modeling, numerical simulations, and physical experimentation to investigate the permeability behavior of nonwoven geotextiles. Mathematical modeling relies on the fiber and pore size characteristics of the geotextiles extracted through two-dimensional image analysis. The numerical simulation method was based on a pore network model acquired through three-dimensional image analysis. The results of the physical experiments served as benchmarks for evaluating the precision of the two methods. These findings underscore the efficacy of mathematical modeling and numerical simulation in predicting the permeability characteristics of nonwoven geotextiles.
Enhancement on compressive strength of Bangkok clay cement using novel high-strength polyethylene fibers
Authors: Pochalard Sakol , Wungsumpow Chalermpon , Piriyakul Keeratikan
Published: May 2024

This study aims to investigate the effect of novel high-strength polyethylene fibers on the unconfined compressive strength (UCS) behavior of concrete produced with admixed Bangkok clay cement. Bangkok clay samples were prepared at a liquid limit of 88% and were added to ordinary Portland cement (OPC) at 2, 4, 6, 8 and 10% by weight; polyethylene fibers were also added at 0.5, 1.0, 1.5, 2.0 and 2.5% by volume. These samples were cured for 7, 14, and 28 days and subjected to an unconfined compressive test. From the test results, the cement content of 8% by weight was the optimum, and a polyethylene fiber content of 1% by volume is recommended. Moreover, the novel high-strength polyethylene fiber with 0.2 mm in diameter and 6 mm in length provided the maximum UCS value.
Numerical parametric study of embedded geosynthetic-reinforced soil abutment
Authors: Zuo Binli , Xu Chao
Published: May 2024

Three-dimensional numerical analysis was conducted to investigate the performance of embedded geosynthetic-reinforced soil abutments. The numerical model was validated using field-monitoring data. A parametric study was conducted to investigate the key factors affecting the performance of the embedded abutment under the working conditions, including the pile offset distance, pile diameter, pile spacing, and bridge load. The piles exhibited a retaining rather than a pushing effect in these cases due to the relatively high stiffness and negative skin friction of the piles, thus reducing the loads exerted on the facing wall. The lateral displacement of the facing wall significantly increased as the pile offset distance decreased mainly due to the reduced anchor length of the reinforcement and enhanced retaining effect of the piles. As the pile diameter increases, the deflection of the facing wall is constrained by factors such as increased bearing width, limited displacement, and enhanced retention effect of thepiles. This is an efficient way to increase the pile density near the abutment centerline to control thedeformation of the facing wall. An increase in the vertical bridge load resulted in a decrease in negative skin friction, leading to increased foundation settlement and lateral displacement of the facing wall.
Prediction and optimization of heat extraction in ground source heat pump system using surrogate model
Authors: Chaoran Wang , Chanjuan Han
Published: May 2024

Ground source heat pump (GSHP) system, which extracts underground heat for building heating and cooling, uses renewable energy to decrease CO2 emissions for the goals of carbon peaking and carbon neutrality. Hence, the prediction and optimization work is significate especially for existing GSHP system. This study focuses on the prediction of heat extraction and optimization of operational strategy based on a three-story house installed with GSHP system located in Cleveland, Ohio, USA. Firstly, the numerical model is built to simulate operation of ground heat exchanger (GHE). Then, Latin hypercube sampling (LHS) is employed to generate different parameter combinations that are calculated to get the heat extraction results for training XGBoost-based surrogate model. Finally, the particle swarm optimization (PSO) is used to realize the optimization of operational strategy. The results indicate that the numerical model can simulate the GHE well, and the accuracy of surrogate model can reach 0.990. The COP of GSHP system is maximized to protect the soil heat balance and reduce the electrical energy consumption. The optimization method also makes it possible to evaluate the heat extraction capability, and prepare for the extra heat demand in advance.
Phosphate removal by acid-activated and chitosan-composite clayey soils
Authors: Verma Gaurav , Reddy Krishna R
Published: May 2024

Phosphate is a vital nutrient for aquatic organism growth, but excessive levels can lead to eutrophication, with detrimental effects on receiving water bodies. Adsorption using clay soils can address phosphate release and has gained attention owing to its cost-efficiency and environmental friendliness. To overcome the limited phosphate adsorption capacity of clay soils due to surface charges, the combined effects of acid activation and composite formation with chitosan were investigated. Kaolin and bentonite were selected for acid activation, while chitosan varieties with low, medium, and high molecular weights were chosen for composite formation. Batch tests were individually conducted on acid-activated clay soils and composites of acid-activated clay soils with chitosan over 24 h, varying the initial phosphate concentrations. For acid activation, clay soils were treated with 6N hydrochloric acid, whereas composite formation was achieved via combination with each chitosan variant. Acid-activated kaolin and bentonite individually exhibited phosphate removal efficiencies ranging 99.8–79.8% and 97.1–47.2%, respectively. Among their respective composites, acid-activated kaolin with medium-molecular-weight chitosan and acid-activated bentonite with low-molecular-weight chitosan had the highest phosphate removal efficiencies. Therefore, in contrast to kaolin, acid activation or composite formation of acid-activated bentonite with chitosan can improve its phosphate removal efficiency.
Influence of extraction and injection conditions on the performance of thermal-enhanced soil vapor extraction
Authors: Yang Chun-Bai-Xue , Feng Shi-Jin , Zheng Qi-Teng
Published: May 2024

Thermal-enhanced soil vapor extraction (T-SVE) is an in-situ remedial technique that can address the limitations of contaminant mass transfer and soil permeability. The relative humidity of the injected air, heating temperature of the thermal well, extraction pressure, and extraction mode are important design parameters of a T-SVE system that determine the temporal and spatial distributions of soil temperature and removal rate. Using a thermal–hydraulic–chemical coupled model with the interphase mass transfer of contaminants and water evaporation/condensation, this study investigated the effects of relative humidity, heating temperature, extraction pressure, and extraction mode on T-SVE performance. The results showed that with an increase in relative humidity, the heating temperature of the contaminated soil significantly improved; however, the removal rate of contaminants decreased, particularly in the late stage of remediation. Considering the heating temperature of the thermal well, a critical air relative humidity value that significantly affects the removal rate of contaminants was observed. The heating temperature of the thermal well must be considered in engineering design; however, the evaluation of the relative humidity of the air cannot be ignored.
Cavern spacing of CAES cavern group in hard rock based on plastic zone and deformation analysis
Authors: Sun Zeyuan , Zhao Cheng , Qian Yuan , Xing Jinquan , Niu Jialun
Published: May 2024

Existing research on layout parameters of compressed air energy storage (CAES) cavern groups in hard rock has indicated that the key influential factors for group stability include buried depth, diameter, and cavern spacing. Among these, in contrasting to other factors, the research on cavern spacing is limited. This paper focuses on the issue of safe spacing and proposes a numerical method to determine it. By establishing a series of finite element models, the stress state of surrounding rock, changes in shape, equivalent plastic strain of plastic zone, and cavern wall deformation under different spacing have been studied. When a group of air storage caverns in rows is subjected to high internal pressure, for a small spacing, the plastic zone of the surrounding rock between two caverns is connected. Here, the size of the plastic zone, equivalent plastic strain value, and deformation of the cavern wall are relatively large, making the surrounding rock highly susceptible to damage. As the spacing increases, the horizontal width of the plastic zone, the maximum equivalent plastic strain value, the displacement changes of the cavern wall remain stable. This spacing is virtually the same as that when the plastic zone of the surrounding rock is no longer connected and can be selected as a safe spacing. This study explores the design of cavern safe spacing of underground CAES cavern groups and discusses several influencing factors, which can provide references for follow-up energy storage engineering and research.
Numerical simulation of fingering in the underground hydrogen storage
Authors: Ren T , Shen X , Zhang F
Published: May 2024

Underground hydrogen storage has garnered interest in recent years owing to the considerable demand for clean energy. Hydrogen is more diffusive than air and has relatively low density and viscosity. These unique properties induce distinct hydrodynamic phenomena during hydrogen storage. Cushion gas has been proven to be a potential remedy for attenuating the adverse impacts of underground hydrogen storage. To investigate the influence of the cushion gas, a microscopic numerical simulation was performed with Fluent software using the Eulerian multi-fluid model. Carbon dioxide, nitrogen, and methane are usually used as the preferred candidates for cushion gases in underground hydrogen storage systems. In this study, nitrogen was used as the cushion gas and was injected along with hydrogen into heterogeneous porous media with volume fractions ranging from 0% to 70%. A parameterization study was then performed to elucidate the influences of the injection rate and viscosity of the fluid on the fingering pattern. Two representative types of fingering, viscous fingering and capillary fingering, were observed under different gas mixtures and boundary conditions. After the simulation, an image analysis was performed to capture the evolution of the fingering pattern. The specific fingering area, number of branches, and fractal dimensions are proposed as geometric indices to describe the shape of the fingering pattern. The results showed that there was a remarkable enhancement in saturation due to the injection of the cushion gas, depending on the concentration of the gas mixture. This study offers insight on the design of gas mixture injection in underground hydrogen storage and can be further extended to the hydrochemo–mechanical coupled numerical simulation of multiphase gas injection in porous media.
Investigating combined effects of saturation–desaturation cycles and cyclic stress resistance of reinforced biopolymer-treated soil
Authors: Aneke Frank I. , Kalumba Denis
Published: May 2024

Throughout their service life, subgrades endure significant stress from cyclic traffic and seasonal moisture fluctuations. This study aims to evaluate the moisture variation and cyclic stress resistance of reinforced and biopolymer-treated soils, which were treated with varying percentages (0.25%, 0.5%, 0.75%, and 1.0%) of xanthan gum (XG) and sisal fiber, to determine the level of tolerance a subgrade can sustain. Wetting–drying (W-D) cycle tests, unconfined compressive strength (UCS) tests, and dynamic resilient modulus (DRM) tests were conducted to assess the resistance of the treated soils to moisture variation and cyclic stress. The findings indicate that biopolymer-treated specimens retained over 95% of their original mass after 15 cycles, whereas fiber-reinforced soil exhibited a 9.1% loss in mass. Furthermore, the DRM of the reinforced soil improved, demonstrating greater resistance to cyclic stress compared to biopolymer-treated soils. Fiber-reinforced soils exhibited strain-hardening responses at low cyclic stress levels and maintained stress tolerance even at high cyclic stress levels without signs of strain deformation. Conversely, the UCS of the biopolymer-treated soil surpassed that of the fiber-reinforced soil due to the brittleness of the specimens.