Transportation Geotechnics最新文献

{"title":"Evaluation of the collapse susceptibility of loess using machine learning","authors":"","doi":"10.1016/j.trgeo.2024.101327","DOIUrl":"10.1016/j.trgeo.2024.101327","url":null,"abstract":"<div><p>Evaluating collapse susceptibility of loess is essential for the construction of transportation lines in loess regions as it provides guidance for ground treatment. For the existing methods, a large number of boreholes need to be drilled along transportation lines to collect intact samples for laboratory tests, which make them very time and cost-consuming. In this study, loess’s collapse susceptibility is evaluated using Multi Expression Programming (MEP) and Back-Propagation Neural Network (BPNN). According to analysis of wetting-induced loess collapse, the gravimetric water content at the initial state (<span><math><msub><mi>w</mi><mn>0</mn></msub></math></span>), net vertical stress (<span><math><mrow><mi>σ</mi><mo>-</mo><msub><mi>u</mi><mi>a</mi></msub></mrow></math></span>), void ratio at the initial state (<span><math><msub><mi>e</mi><mn>0</mn></msub></math></span>), void ratio at the liquid limit state (<span><math><msub><mi>e</mi><mi>L</mi></msub></math></span>), and plastic index (<span><math><msub><mi>I</mi><mi>p</mi></msub></math></span>) are chosen as input variables. A comprehensive database incorporating 200 oedometrically soaking tests is established to train and test the two algorithms. The collapse potentials of loess are well predicted using MEP and BPNN, as demonstrated by high values of coefficient of determination (<span><math><mrow><mspace></mspace><msup><mrow><mi>R</mi></mrow><mn>2</mn></msup><mo>&gt;</mo><mn>0.88</mn></mrow></math></span>) and small values of mean absolute error <span><math><mrow><mo>(</mo><mi>M</mi><mi>A</mi><mi>E</mi><mo>&lt;</mo><mn>0.008</mn><mo>)</mo></mrow></math></span> and root mean squared error <span><math><mrow><mo>(</mo><mi>R</mi><mi>M</mi><mi>S</mi><mi>E</mi><mo>&lt;</mo><mn>0.012</mn><mo>)</mo></mrow></math></span>. Following ASTM D5333-03 <span><span>[5]</span></span>, the degree of loess collapse is classified with accuracies of 98 % and 90 % for MEP and BNPP respectively. Furthermore, sensitivity analysis shows the contribution of each variable to the prediction of collapse potential follows the order of <span><math><mrow><msub><mi>e</mi><mn>0</mn></msub><mo>&gt;</mo><msub><mi>e</mi><mi>L</mi></msub><mo>&gt;</mo><msub><mi>I</mi><mi>p</mi></msub><mo>&gt;</mo><mi>σ</mi><mo>-</mo><msub><mi>u</mi><mi>a</mi></msub><mo>&gt;</mo><msub><mi>w</mi><mn>0</mn></msub></mrow></math></span>. The machine learning is expected to assist the code of practice ASTM D5333-03 <span><span>[5]</span></span> in achieving an efficient site-investigation of collapsible loess for the construction of transportation lines.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930760","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}

{"title":"Shear behaviors of expansive soils over a wide confining pressures range and their impacts on strength parameters","authors":"","doi":"10.1016/j.trgeo.2024.101328","DOIUrl":"10.1016/j.trgeo.2024.101328","url":null,"abstract":"<div><p>Understanding the shear behaviors of expansive soils under a wide range of confining pressures <em>σ</em>₃ is crucial for effectively managing their shallow hazards, especially at low <em>σ</em>₃ values. The shear behaviors of expansive soils under the low <em>σ</em>₃ values exhibit significant differences with those under the high <em>σ</em>₃ values, which have been inadequately addressed in existing research. This paper investigated the shear behaviors of two expansive soils across a wide range of <em>σ</em>₃ values (i.e., 15–400 kPa) through consolidated undrained triaxial tests. The results showed a significant nonlinear relationship between the shear strength and <em>σ</em>₃, particularly at the low <em>σ</em>₃ values. The nonlinearity of shear strength versus <em>σ</em>₃ in shallow expansive soils was described by a modified power function. As <em>σ</em>₃ decreased, both the brittleness index <em>λ</em> and curvature <em>κ</em> increased nonlinearly. Comparisons between the tangent method, based on the modified power function, and the <em>K</em>_f method, based on the Mohr-Coulomb criterion, suggested that neglecting the nonlinearity of shear strength versus <em>σ</em>₃ led to overestimations of the cohesion and underestimations of the internal friction angle at low <em>σ</em>₃ values, and the reverse trend was observed at high <em>σ</em>₃ values. The magnitude of these deviations depended on both the shear strength nonlinearity and the selected <em>σ</em>₃ values. The findings presented herein are helpful for the mitigation of shallow hazards in roadbeds, slopes, and foundation engineering associated with expansive soils.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930759","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}

{"title":"Non-linear critical speed in high-speed ballasted railways with ground reinforcement","authors":"","doi":"10.1016/j.trgeo.2024.101325","DOIUrl":"10.1016/j.trgeo.2024.101325","url":null,"abstract":"<div><p>When constructing or upgrading high-speed railway lines on soft soils, reinforcing the soil foundation becomes crucial. This not only involves small track displacements but also increases the critical speed, thereby ensuring safe and efficient regular operations. Nevertheless, existing studies on the critical speed phenomenon in high-speed railway tracks with ground reinforcement are limited, and they all assume a linear elastic behavior for both the soils and reinforcement materials. The main novelty of this research is that it presents the first study on the effect of non-linear soil behavior on the critical speed of high-speed railway ballasted tracks with soil reinforcement and introduces a novel simplified approach based on an equivalent homogeneous soil layer by replacing the soil layer containing inclusions/columns. To accomplish this, a full 3D non-linear numerical model was developed and experimentally validated. The findings from a detailed and comprehensive parametric analysis demonstrate a significant influence of non-linear behavior on the critical speed, resulting in reductions of up to 30% compared to the linear elastic scenario. Furthermore, it is found that the soil-reinforcement stiffness contrast, the area replacement ratio, and the plasticity index of the soil foundation play a crucial role in the critical speed. Other aspects such as the installation pattern and the thickness of soft soil have a relatively lower impact on the critical speed.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214391224001466/pdfft?md5=f53b74893e2253ba1fdfcf376e49eeaf&pid=1-s2.0-S2214391224001466-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An approach for strength development assessment of cement-stabilized soils with various sand and fine contents","authors":"","doi":"10.1016/j.trgeo.2024.101323","DOIUrl":"10.1016/j.trgeo.2024.101323","url":null,"abstract":"<div><p>Cement stabilization is a well-established ground improvement technique. However, there have been limited investigations aimed at the effect of heterogeneous soil types with varying amounts of coarse-grained (sand) and fine-grained (silt and clay) substances, on the strength enhancement of cement-stabilized soils. In this cement stabilization research study, sand (S) and clayey silt (F) were mixed together to have a variety between coarse- and fine-grained fractions at 100, 75, 50, 25, and 0 % by dry weight, designated as the ratio of S:F=100:0, 75:25, 50:50, 25:75, and 0:100, respectively. The water content was prepared at the range of 1.25–2.50 optimal water content to simulate field applications. The strength enhancement of cement-stabilized soils was influenced by the fine content, water content, and cement content. The soil–water to cement ratio (s-w/c) was effectively incorporate the impact of both water and cement contents on the strength enhancement, for a given a specific fine content. The generalized correlation between unconfined compressive strength, <em>q_u</em> and <em>s-w/c</em> could be represented as a power function: <em>q_u</em> = M/(<em>s-w/c</em>)^N. In this equation, M and N are constants that are primarily influenced by the fine content. The shear strength ratio versus fine content chart was proposed as a means to assess the effect of fine content on the strength of cement-stabilized soil with varying <em>s-w/c</em>. A stepwise approach for assessing the strength enhancement of cement stabilization in soil based on physical characteristics (i.e., plasticity index and fine content) was proposed and validated. The robustness of the proposed approach was realized by the low mean absolute percent error, (MAPE&lt;7.0 %) and high coefficient of determination (R² &gt; 0.95) for measured and predicted strengths comparison. This technique serves as a valuable tool for mix design, specifically in relation to clay mineral and fine content. It supports in making engineering decision regarding the appropriate amount of water and cement needed to achieve strength requirements throughout the requisite curing period, while minimizing the number of repetitions needed.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930762","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}

{"title":"Chemical, mineralogical and geotechnical properties of volcanic ash of Tajogaite (La Palma, Canary Islands, Spain)","authors":"","doi":"10.1016/j.trgeo.2024.101326","DOIUrl":"10.1016/j.trgeo.2024.101326","url":null,"abstract":"<div><p>Volcanic eruption at La Palma island (Tajogaite, 2021) has produced tons of volcanic ash as natural sediments spread all around the island covering existing crops, roads, embankments, buildings, etc., by that way producing damage to environment. For the rehabilitation and reconstruction of island, and its application to adjacent areas, it is practical and economical to employ these volcanic ashes as construction material being encountered in abundant volume, and by that way could be considered as a resource material instead as a waste material, reducing necessary volume of landfills for its deposition. This paper defines the investigation of chemical, mineralogical and geotechnical properties of these deposited materials for its possible reuse by that way providing solution for its recovery. These young volcanic ashes are studied in its fresh natural state, prior to consolidation and cementation has taken place for its chemical, mineralogical and geotechnical characterization. Volcanic ash of Tajogaite is of a poorly graded sandy nature having difficulties for its compaction, having low improvement of relative density by the application of standard compaction methods. Mineralogy analysis indicates it is rich in silica, iron, calcium and alumina oxide, although being necessary the addition of mineral additives for its alkali-activation. Geotechnical characteristics of different samples vary depending on the sampling site, being resistance parameters determined by direct shear test (friction angle 30° to 34°) and deformational properties defined by one-dimensional consolidation test considered low values as of loose sand materials (deformation modulus range from 20 to 40 MPa).</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214391224001478/pdfft?md5=f1ebe83bebbc8425dffb2a0c199e3085&pid=1-s2.0-S2214391224001478-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141930697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of climate change on soil embankments for transport infrastructure","authors":"","doi":"10.1016/j.trgeo.2024.101324","DOIUrl":"10.1016/j.trgeo.2024.101324","url":null,"abstract":"<div><p>The climate is changing. Unequivocal global warming has brought significant changes to our climate system. The Intergovernmental Panel on Climate Change <span><span>[1]</span></span> concludes that climate change will result in both an increase in temperature and changes in the global water cycle, possibly leading to extreme drought–rainfall conditions and freeze–thaw cycles. These developments raise important questions: can existing transport infrastructure such as high-speed railway lines built on soil embankments cope with the aforementioned extreme weather conditions? Do we have enough reliable physical data to design future transportation systems?</p><p>This paper describes a novel environmental chamber capable of simulating, in a geotechnical centrifuge test, the effects of extreme cycles of temperature, rainfall and humidity on an embankment in flight. Using the recently developed centrifuge environmental chamber, a series of centrifuge tests were carried out to assess the influence of thermal cycles on the deformation mechanisms of soil embankments, the influence of extreme drought–rainfall conditions on the stability of embankment slopes, and slope deterioration mechanisms under freeze–thaw cycles. The thermo-hydro-mechanical behaviour of embankments is reported and discussed. Furthermore, new insights into the deformation and failure mechanisms of embankment slopes are revealed, and the design implications for future transport infrastructure are highlighted and discussed.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141839052","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}

{"title":"Dynamic responses of transversely isotropic and layered elastic media with imperfect interfaces under moving loads","authors":"","doi":"10.1016/j.trgeo.2024.101322","DOIUrl":"10.1016/j.trgeo.2024.101322","url":null,"abstract":"<div><p>Flexible pavement is widely used in engineering practice but is often subjected to the moving traffic loads, with imperfect contact behavior at the interfaces between adjacent layers. This study investigates transversely isotropic and layered elastic media with imperfect interfaces under moving vertical and horizontal loads using a semi-analytical method. The governing equation for moving loads is established within a Cartesian coordinate system and by virtue of the Galilean transformation, which is further decoupled into two ordinary differential equations in terms of the powerful Cartesian system of vector functions. General solutions for any layer are obtained, and the dual-variable position method is applied to derive the semi-analytical solutions for the layered pavement in the vector function domain. The lately introduced refined conversion algorithm, originally from the discrete convolution-fast Fourier transform (DC-FFT) algorithm, is applied to obtain the solution in the physical domain, which can efficiently remove the Gibbs effect near the source. The solutions are validated by comparison with existing solutions and numerical examples are presented to study the effect of interface modulus, moving load velocity, Young’s modulus of asphalt concrete and horizontal/vertical loading ratio on the surface dynamic response of the flexible pavement. Finally, the fatigue and rutting life of the pavement structures corresponding to different imperfect interface moduli are analyzed. The present solution provides practical guidance for the design of flexible pavement.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141839293","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}

{"title":"Accelerated surface carbonation of non-plastic silt mixed with hydrated lime","authors":"","doi":"10.1016/j.trgeo.2024.101320","DOIUrl":"10.1016/j.trgeo.2024.101320","url":null,"abstract":"<div><p>Chemical stabilization via hydration reactions with cement or lime is a universally applied method to improve the mechanical properties of shallow soils. Accelerated soil carbonation is a nascent approach intended to bypass this reaction. Carbon dioxide gas is deliberately introduced at high concentrations to react with the alkali additives and precipitate a carbonate binder that permanently sequesters carbon dioxide in the process. A large soil box experiment was performed to examine the efficacy of an accelerated surface carbonation approach, which has the potential to be applied over large areas. High concentrations of carbon dioxide gas were introduced at grade beneath a seal to facilitate vertical penetration into lime-mixed silt. The real-time progression of accelerated soil carbonation was captured with a gas flowmeter and a distributed array of embedded thermocouples and bender elements for the first time. Post-carbonation measurements of binder content and California Bearing Ratio (CBR) verified the degree of carbonation and associated mechanical improvement. Synthesis of real-time monitoring data and post-carbonation measurements indicate carbonation progressed top-down 150 to 200 mm below grade within 5 h, resulting in a substantial increase in strength and stiffness. Potential challenges and benefits associated with adoption of accelerated surface carbonation are discussed.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141845515","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}

{"title":"Experimental study on the resilient and permanent deformation of a compacted waste foundry sand","authors":"","doi":"10.1016/j.trgeo.2024.101319","DOIUrl":"10.1016/j.trgeo.2024.101319","url":null,"abstract":"<div><p>The use of Waste Foundry Sands (WFS) as a construction material in geotechnical works is strategic because it allows the consumption of large amounts of this waste worldwide, typically discarded in landfills. Beyond the achievement of environmental requirements, the construction industry needs a comprehensive understanding of its mechanical properties, which is a challenge to enhance the recycling or reuse of WFS. This paper investigates the resilient and permanent deformation of a compacted WFS under repeated load. These features are necessary to understand the behavior of this material in the context of pavement design. A campaign of laboratory tests was carried out based on cyclic triaxial tests to measure resilient modulus (RM) and permanent deformation (PD). Specimens were prepared with different densities, which achieved varying compaction energy (600, 1260, and 2700 kJ/m³) but keeping saturation degree varying in a narrow range. Results demonstrated that the resilient modulus ranges from approximately 80 to 380 MPa, with confining stress controlling its behavior and having a small effect on compaction energy. Permanent deformation reaches almost 3 % after 150.000 load cycles for the maximum confining and deviatoric stresses and is controlled by the confining and deviatoric stress. The WFS reached the shakedown state for all the densities and stress-state evaluated, in a pattern below plastic creep shakedown and plastic limit shakedown. The best models to describe the experimental results were investigated, and the fitting parameters were also found. The authors also demonstrated that the resilient modulus measured on the last 100.000 cycles of permanent deformation tests is similar to the values measured on resilient modulus tests, which allows to characterize the resilient and permanent deformation using only the permanent deformation tests.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141850994","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}

{"title":"Characteristics analysis of leakage diseases of Beijing underground subway stations based on the field investigation and data statistics","authors":"","doi":"10.1016/j.trgeo.2024.101317","DOIUrl":"10.1016/j.trgeo.2024.101317","url":null,"abstract":"<div><p>With a continuous increasing of the underground water level of Beijing, many leakage diseases induced by the structural defect have been exposed in the subway tunnels that have been put into operation. The leakage diseases of underground subway stations may severely cause the safety and durability problems of the structure. Moreover, it could affect the passenger experience and seriously threaten the operation safety. Therefore, this paper collected the leakage states of a total of 258 underground subway stations in 16 lines of Beijing by field investigation, which include the number of average leakage points, leakage types and classification, distribution scenes of leakage, the construction methods and operation ages of subway stations and so on. Besides, in order to further investigate the causes of the leakage diseases, three typical cases of Beijing subway stations with severe leakage diseases, which were constructed by different methods, were selected to carry out the statistical analysis of leakage disease. The typical positions of leakage diseases of Beijing subway stations with different construction methods were presented by three-dimensional modelling, and the leakage characteristics of each station were analyzed. Finally, based on the field investigation and data statistics, a data-based Bayesian network leakage prediction model to evaluate the leakage risk of subway stations was constructed. This research can provide an intuitive reference for early warning, monitoring and prevention of leakage diseases of metro subways in operation.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141960597","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}