Transportation Geotechnics最新文献_第7页

Influence of Collapsible Shape of Loess Foundation on High-Speed Railway Subgrade under Train Vibration Loading

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-01 DOI: 10.1016/j.trgeo.2024.101414

Zejie Li , Xiaolin Weng , Shuaijie Guo , Muhan Yan , Chunli Wang

Collapsible loess has special sensitivity to water, and its engineering mechanical properties deteriorate significantly after immersion in water, causing the foundation to sink, which seriously threatens the safety and stability of the high-speed railway subgrade under train vibration loading. Studying this effect is essential to prevent and control the disasters of high-speed railway subgrades. In this study, a model with the function of simulating foundation settlement is established to conduct disaster testing of high railway subgrade under train vibration loading. The results indicate that when different foundation shapes are settled, the surface of the subgrade under static load is gradually settled in a short time, and the settlement value of the track surface is lower than that of the corresponding subgrade surface. Under train vibration load, the maximum dynamic settlement occurs at the middle of the subgrade slope, which is smaller than the corresponding settlement under static load. The number of stabilization times required from different monitoring positions on the subgrade surface is different under different excitation forces, and the number of stabilization times required is more in the middle of the subgrade slope and the slope shoulder. The influence of train speed on subgrade has a critical respond speed that increases with increasing vibration times. There are horizontal, vertical and 45° angle cracks in the middle of subgrade slope. It is qualitatively assessed that the slope of the high-speed railway subgrade in the collapsible loess area is unstable under the effect of train load. The data and rules provided in this document provide some reference values for the construction of a high-speed railway in the collapsible loess area.

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引用次数: 0

Settlement prediction of a high embankment based on non-linear regression and neural network algorithm

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-01 DOI: 10.1016/j.trgeo.2024.101443

Enhui Yang , Kai Wang , Jinhong He , Kaiwen Liu , Junxin Wang , Haopeng Zhang , Yanjun Qiu

This study reports in-situ measured data from single-point settlement meters buried in layers at the road shoulders and the center of a high embankment respectively. Based on the measured data, the nonlinear fitting models and neural network algorithm were proposed to establish the method of settlement prediction, and the mean absolute percentage error (MAPE) and mean square errors (MSE) were used to evaluate the accuracy of the settlement prediction model. The results show that the MAPE value of the exponential curve prediction model is less than 10%, and the MAPE value of the hyperbolic model is between 10% and 20%, and the MAPE value of the logarithmic model is greater than 20%, which shows that the exponential curve model of the three nonlinear fitting models has the highest accuracy. After establishing the back propagation (BP) neural network model, the settlement data of the four monitoring points were learned and trained, and the prediction accuracy of the two BP neural network prediction models and the exponential curve prediction model were compared. The model fitting coefficient of R² of BP neural network were both greater than 0.99, and the MSE and MAPE were less than 1%. In addition, the multi-step rolling BP neural network prediction model has the highest prediction accuracy, followed by the BP neural network prediction model based on influencing factors while the exponential curve prediction model has the worst performance and weak practicability. This research can provide new inspiration for embankment settlement prediction and give technical support to monitor the disaster of high embankment.

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引用次数: 0

A novel thermodynamic constitutive model of coarse-grained soils considering the particle breakage

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-01 DOI: 10.1016/j.trgeo.2024.101462

Bing Bai , Bixia Zhang , Hongju Chen , Peipei Chen

The granular thermodynamics was extended to the solid–liquid system, developing a constitutive model for coarse-grained soils (CGS). The model combined the physical conservation equation, thermodynamic differential equation and entropy increase equation to construct a new elastic potential energy density function (EDF). The dissipation energy caused by particle breakage and deformation was associated with macroscopic mechanical behavior using dissipation system, migration coefficients, and particle breakage function. The particle breakage function was applied to convey the change in particle gradation, as well as the critical-state stress ratio. The model integrated the concept of critical-state line drift, revealing the attenuation of shear stiffness/strength due to dilatancy/shrinkage. Test results of Toyoura sand (TS), crushed cambric slate (CCS), and calcareous sand (CS) were selected to validate the proposed model, manifesting a great advantage and high prediction accuracy.

引用次数: 0

Seismic response of high-filled reinforced embankment supported by pile and slab structure on slope terrain

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-01 DOI: 10.1016/j.trgeo.2024.101475

Weiting Deng , Xuanming Ding , Changwei Yang , Qiang Ou , Chunyan Wang , Guangwei Cao , Yiwen Xin

In this study, the shaking table tests were conducted to investigate the seismic response of a high-filled reinforced embankment supported by pile and slab structure on slope terrain. The macroscopic damage phenomena of the test model, acceleration response, displacement, dynamic earth pressure and bending moment of the pile were thoroughly examined and discussed. The results revealed that the high-filled subgrade reinforced embankment had a favorable seismic stability. Despite the absence of collapse after 1.2 g seismic load, there was a certain extent reduction in structural resonance frequency. The dynamic earth pressure behind the pile initially increased from the top to the bottom and subsequently decreased near the soil boundary. However, with the seismic magnitude increasing, the peak value of the earth pressure near the pile bottom gradually increased due to pile rotation. The bending moment of the pile presented a bow-shaped distribution. The acceleration exhibited a notable amplification effect along the height of model, while the horizontal acceleration amplification factor decreased with seismic magnitude. Furthermore, the time–frequency domain characteristics and energy distribution of the model were investigated using the Hilbert-Huang Transform. This study provides a theoretical basis for the design of supporting structures for high-filled subgrades in high-intensity earthquake areas.

{"title":"Seismic response of high-filled reinforced embankment supported by pile and slab structure on slope terrain","authors":"Weiting Deng , Xuanming Ding , Changwei Yang , Qiang Ou , Chunyan Wang , Guangwei Cao , Yiwen Xin","doi":"10.1016/j.trgeo.2024.101475","DOIUrl":"10.1016/j.trgeo.2024.101475","url":null,"abstract":"<div><div>In this study, the shaking table tests were conducted to investigate the seismic response of a high-filled reinforced embankment supported by pile and slab structure on slope terrain. The macroscopic damage phenomena of the test model, acceleration response, displacement, dynamic earth pressure and bending moment of the pile were thoroughly examined and discussed. The results revealed that the high-filled subgrade reinforced embankment had a favorable seismic stability. Despite the absence of collapse after 1.2 g seismic load, there was a certain extent reduction in structural resonance frequency. The dynamic earth pressure behind the pile initially increased from the top to the bottom and subsequently decreased near the soil boundary. However, with the seismic magnitude increasing, the peak value of the earth pressure near the pile bottom gradually increased due to pile rotation. The bending moment of the pile presented a bow-shaped distribution. The acceleration exhibited a notable amplification effect along the height of model, while the horizontal acceleration amplification factor decreased with seismic magnitude. Furthermore, the time–frequency domain characteristics and energy distribution of the model were investigated using the Hilbert-Huang Transform. This study provides a theoretical basis for the design of supporting structures for high-filled subgrades in high-intensity earthquake areas.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"50 ","pages":"Article 101475"},"PeriodicalIF":4.9,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Undrained Triaxial Compression Testing of Sand-Low Plastic Silt Mixtures

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-01 DOI: 10.1016/j.trgeo.2025.101482

Suleyman Demir , Ali Firat Cabalar

This study presents some consolidated undrained triaxial compression (CU) tests of sand-low plastic silt (ML) mixtures, with ML contents of 0 %, 10 %, 20 %, 30 %, 40 %, and 50 %. The tests were performed on each mixture at three effective consolidation stresses (ECSs) of 50, 100, and 150 kPa. Triaxial testing equipment equipped with submersible local linear variable differential transformers (LVDTs) was employed to obtain accurate non-linear stiffness responses of the tested specimens over the course of the test. The testing results showed that the minimum and maximum void ratios (e_min and e_max) of the specimens decreased until 20 % ML additions and then increased. Increasing the ECS of the test increased the deviatoric stress, contractive volumetric response and secant modulus (E_u) of all mixtures. Increasing the ML content at a given ECS decreased the deviatoric stress of the mixtures. The ML additions increased the excess pore water pressure (PWP) of the mixtures. The sand with low ML contents (0, 10, and 20 %) exhibited an initial contractive behaviour, followed by a dilative response. However, sand mixed with 30, 40, and 50 % ML were dominated by contractive response. The E_u values of sand decreased with the ML additions. Consequently, these suggest that sand grains can retain their dilative nature and stability when the ML contents are low (i.e., sand-dominated soil matrix). However, when ML dominates the soil matrix, the mixtures exhibited a dominant contractive response with decreasing mean effective stress in their stress paths.

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引用次数: 0

Influence of number of load cycles on the resilient response of soils under repeated load triaxial tests

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2025-01-01 DOI: 10.1016/j.trgeo.2025.101493

Gabriel Grassioli Schreinert, Camila Kern, Helena Lunkes Strieder, Lélio Antônio Teixeira Brito, Washington Peres Núñez

Over the course of its useful life, a pavement structure is subjected to a large number of load cycles, being exposed to varied and broad stress states, and thus establishing a stress history relative to each material. So, the study and understanding of the influence of the number of load cycles on the mechanical behaviour of unbound materials, especially on the resilient response of soils, is fundamental for appropriate pavement design and management. In this context, this paper studied the mechanical behaviour of three soils as pavement materials, focusing on evaluating the effects of number of load cycles on their resilient response. Comparative analyses were performed with experimental data and regression models obtained from resilient modulus and permanent deformation (single-stage and multi-stage) tests using the repeated load triaxial equipment. Moreover, the experimental program also covered the variation of compaction energy and moisture, allowing to analyse the correlation between these variables and the influence of number of load cycles. The results reveal two main trends and discussions. Firstly, in cases where similar resilient values and models were obtained from the tests, there is a suggestion to combine both tests for more efficient laboratory analyses. In other cases, a significant increase in resilient values was observed in permanent deformation tests, attributed to a hardening effect, raising discussions regarding the consideration of resilient modulus results obtained through this test in mechanistic-empirical pavement design, as they may better represent field conditions.

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引用次数: 0

An experimental investigation on the arching effect of cohesive materials in trapdoor tests 活门试验中粘性材料拱起效应的实验研究

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2024-11-22 DOI: 10.1016/j.trgeo.2024.101453

Yao Li , Xuchao Du , Xing Dong , Houxian Chen , Zhanglong Guo

This study conducted a series of trapdoor tests on low cohesion material at different buried depths, the failure patterns and the variations of soil pressure were investigated, and the development of the arching effect in trapdoor tests was analyzed. The results showed two failure models for soils: when the buried depth ratio was smaller than 2, two rupture surfaces developed obliquely upward from two sides of the trapdoor and merged into one triangular rupture surface; when the ratio was greater than 2, two rupture surfaces developed vertically upward and merged into one tower-shaped rupture surface. As the burial depth increased, the inner boundaries of the soil arch moved upward, and the widths of the inner and outer boundaries expanded. Furthermore, the maximum arching trajectory, obtained by connecting the maximum tangential stress points, was closer to the inner boundary and shifted towards the outer boundary when the trapdoor was lowered. Based on the experimental results, a new composite arch model was proposed to calculate the soil pressure above a trapdoor, it can better describe the development of soil pressure in a trapdoor test.

本研究对不同埋深的低内聚力材料进行了一系列活门试验，研究了其破坏模式和土压力的变化，并分析了活门试验中拱起效应的发展。结果表明土壤有两种破坏模式：当埋深比小于 2 时，两个破裂面从活门两侧斜向上发展，合并成一个三角形破裂面；当埋深比大于 2 时，两个破裂面垂直向上发展，合并成一个塔形破裂面。随着埋深的增加，土拱的内边界上移，内外边界的宽度扩大。此外，连接最大切向应力点得到的最大拱起轨迹更靠近内边界，而当活门下降时则向外边界移动。根据试验结果，提出了一种新的复合拱模型来计算活门上方的土压力，它能更好地描述活门试验中土压力的发展。

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引用次数: 0

Study of the performance of a 3D modular geosynthetic reinforced soil bridge abutment under overloading 三维组合式土工合成材料加筋土桥梁桥台超载性能研究

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2024-11-21 DOI: 10.1016/j.trgeo.2024.101451

Chen Zhu , Xiaoguang Cai , Yurun Li , Sihan Li , Xin Huang , Honglu Xu

The objective of this study was to investigate the response characteristics of three-dimensional geosynthetic reinforced soil (GRS) bridge abutments subjected to overload conditions in terms of deformation, soil stresses, and reinforcement strains. To this end, a 1:2 scale model of a GRS bridge abutment was constructed and subjected to a detailed analysis when the vertical load was increased in incremental steps. The results showed that the GRS abutment performed well and did not reach the plastic state at six times the service limit state (SLS) load. The settlement at the top of the abutment increases with increasing load, and the settlement results in the central bulging of both the front and wing walls, which is inconsistent with the assumption of plane strain. Therefore, a novel three-dimensional facing displacement model that outperforms traditional calculation methods is presented. The incremental vertical soil stresses in the center of the abutment increased significantly, and the U.S. Federal Highway Administration (FHWA) method better predicted the vertical soil stresses on the GRS bridge abutments under SLS loads; however, this method underestimates the incremental vertical soil stresses under overloads. The maximum reinforcement strain occurred in the middle of the abutment, and the deformation of the reinforcement was not uniform under overload, indicating that an overload may lead to the destruction of the reinforcement under the beam seat. The results of this study can serve as a reference for the design and application of GRS bridge abutments.

本研究的目的是研究三维土工合成加筋土（GRS）桥台在超载条件下的变形、土应力和钢筋应变的响应特征。为此，构建了一个1:2比例的GRS桥台模型，并对竖向荷载逐级增加的情况进行了详细分析。结果表明：在6倍于使用极限状态（SLS）荷载作用下，GRS桥台性能良好，未达到塑性状态；桥台顶部沉降随荷载的增大而增大，沉降导致桥台前壁和翼壁均出现中心胀形，这与平面应变假设不一致。为此，提出了一种优于传统计算方法的三维面位移模型。桥台中心竖向土应力增量显著增大，美国联邦公路管理局（FHWA）方法较好地预测了SLS荷载作用下GRS桥台的竖向土应力；然而，这种方法低估了超载作用下土壤垂直应力增量。最大钢筋应变发生在桥台中部，超载作用下钢筋变形不均匀，说明超载可能导致梁座下钢筋破坏。研究结果可为GRS桥台的设计和应用提供参考。

{"title":"Study of the performance of a 3D modular geosynthetic reinforced soil bridge abutment under overloading","authors":"Chen Zhu , Xiaoguang Cai , Yurun Li , Sihan Li , Xin Huang , Honglu Xu","doi":"10.1016/j.trgeo.2024.101451","DOIUrl":"10.1016/j.trgeo.2024.101451","url":null,"abstract":"<div><div>The objective of this study was to investigate the response characteristics of three-dimensional geosynthetic reinforced soil (GRS) bridge abutments subjected to overload conditions in terms of deformation, soil stresses, and reinforcement strains. To this end, a 1:2 scale model of a GRS bridge abutment was constructed and subjected to a detailed analysis when the vertical load was increased in incremental steps. The results showed that the GRS abutment performed well and did not reach the plastic state at six times the service limit state (SLS) load. The settlement at the top of the abutment increases with increasing load, and the settlement results in the central bulging of both the front and wing walls, which is inconsistent with the assumption of plane strain. Therefore, a novel three-dimensional facing displacement model that outperforms traditional calculation methods is presented. The incremental vertical soil stresses in the center of the abutment increased significantly, and the U.S. Federal Highway Administration (FHWA) method better predicted the vertical soil stresses on the GRS bridge abutments under SLS loads; however, this method underestimates the incremental vertical soil stresses under overloads. The maximum reinforcement strain occurred in the middle of the abutment, and the deformation of the reinforcement was not uniform under overload, indicating that an overload may lead to the destruction of the reinforcement under the beam seat. The results of this study can serve as a reference for the design and application of GRS bridge abutments.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"50 ","pages":"Article 101451"},"PeriodicalIF":4.9,"publicationDate":"2024-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142743886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Theoretical analysis of stresses and displacements of twin tunnels excavated in saturated ground 饱和地层中双线隧道的应力和位移理论分析

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2024-11-21 DOI: 10.1016/j.trgeo.2024.101449

Xingchen Jia , Huaning Wang , Fei Song , Alfonso Rodriguez-Dono

The main objective of this study is to establish a general analytical model for investigating the hydro-mechanical problems of twin tunnels excavated in elastic saturated ground, taking into account the influence of seepage flow on the mechanical responses. All hydro-mechanical (HM) boundary conditions are satisfied to derive the analytical solutions. An innovative analytical complex function in the HM coupled framework, integrating complex variable theory and the Schwarz alternating method, has been developed with the consideration of arbitrary sizes and arrangements of twin tunnels. The convergence speed of the alternating method is quite fast, generally achieving enough accuracy within three iteration steps in the solving procedure, guaranteeing the application of the developed solutions in geotechnical engineering. The results obtained from these solutions match well with those of the numerical predictions, verifying the proposed analytical theory and the developed analytical solutions.

Additionally, sensitivity analyses are performed to investigate mechanical responses of stresses and displacements of host rocks subjected to different engineering cases, including geometry and boundary conditions of twin tunnels. Results indicate a significant increase in the major principal stresses and deformations with rising seepage forces, suggesting that seepage flow can pose underground structures to dangerous conditions. Consequently, the influence of seepage flow plays a significant role in the stability analysis of tunnelling in water-rich geological areas. The proposed analytical approach offers an innovative and efficient alternative for the preliminary design of twin tunnels excavated in saturated ground, providing valuable insights for engineering applications.

本研究的主要目的是建立一个通用分析模型，用于研究在弹性饱和地层中开挖的双隧道的水力机械问题，同时考虑到渗流对机械响应的影响。所有水力机械 (HM) 边界条件都得到满足，从而得出分析解。在 HM 耦合框架下，结合复变理论和施瓦茨交替法，开发了一种创新的分析复变函数，并考虑了双隧道的任意尺寸和排列。交替法的收敛速度相当快，一般在求解过程的三个迭代步骤内就能达到足够的精度，从而保证了所开发的解决方案在岩土工程中的应用。此外，还进行了敏感性分析，以研究不同工程情况（包括双隧道的几何形状和边界条件）下主岩应力和位移的力学响应。结果表明，随着渗流力的增加，主要主应力和变形也会明显增加，这表明渗流会对地下结构造成危险。因此，渗流的影响在富水地质区隧道稳定性分析中起着重要作用。所提出的分析方法为饱和地层中开挖的双线隧道的初步设计提供了一种创新而有效的选择，为工程应用提供了宝贵的见解。

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引用次数: 0

Evaluating the hydraulic behavior of sandy fouled ballast: A case study from Inner Mongolia, China 含砂污垢压载物的水力特性评价——以内蒙古为例

IF 4.9 2区工程技术 Q1 ENGINEERING, CIVIL

Transportation Geotechnics

Pub Date : 2024-11-15 DOI: 10.1016/j.trgeo.2024.101437

Ahmed Nabil Ramadan , Jinxi Zhang , Peng Jing , Li Zhang , Muhammad Murtaza

This study examines the hydraulic behavior of sandy fouled ballast from Wuhai-Jilantai railway in Inner Mongolia, China, with a focus on its response to variable wetting and drying conditions influenced by climate change. The material characteristics were investigated, and it was classified as poorly-graded gravel (GP) according to the Unified Soil Classification System (USCS). This classification indicated that the material consisted primarily of gravel and sand with few fine particles. Large-scale infiltration column tests were conducted to assess the hydraulic properties, simulating precipitation rates of Wuhai (8 mm/hr) and Marsa Matruh (43 mm/hr). The results showed that under Wuhai conditions, saturation levels reached 49.3 % at the column top and 75.8 % at the bottom. In contrast, the ballast was fully saturated under Marsa Matruh’s precipitation rate. The saturated hydraulic conductivity, determined using constant head permeability tests, was measured at 1.06*10⁻⁵ m/s. Saturation levels after drainage were 39 % and 97 % at the column top and bottom, respectively. Then, a notable increase in evaporation rates facilitated by enhanced ventilation compared to applying high temperatures only. Unimodal and bimodal models were applied for understanding the Soil-Water Characteristic Curve (SWCC) and hydraulic conductivity. This research uncovers previously unreported heterogeneity in sandy fouled ballast and demonstrates the efficacy of bimodal models, providing a superior fit and more accurate prediction of hydraulic behavior, underscoring the critical role of sophisticated modeling techniques in predicting the impacts of climate variability on railway infrastructure.

本文研究了内蒙古乌海-吉兰台铁路沙质污垢道砟的水力特性，重点研究了其对气候变化影响下不同干湿条件的响应。根据美国统一土壤分类系统（USCS）将其分类为差级配砾石（GP）。这种分类表明，材料主要由砾石和沙子组成，很少有细颗粒。采用大型入渗柱试验，模拟乌海（8 mm/hr）和Marsa Matruh （43 mm/hr）的降水速率，评估水力学性能。结果表明，在乌海条件下，塔顶和塔底的饱和度分别达到49.3%和75.8%。而在Marsa Matruh降水速率下，压载水完全饱和。采用恒水头渗透性试验测定饱和水力导电性，测量速度为1.06*10−5 m/s。排水后柱顶、柱底饱和度分别为39%、97%。然后，与仅应用高温相比，增强通风促进了蒸发速率的显着增加。采用单峰模型和双峰模型来理解土-水特征曲线（SWCC）和水导率。这项研究揭示了以前未报道的沙质污染压舱物的异质性，并证明了双峰模型的有效性，提供了更好的拟合和更准确的水力行为预测，强调了复杂建模技术在预测气候变化对铁路基础设施的影响方面的关键作用。

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引用次数: 0