Pub Date : 2024-10-01DOI: 10.1016/j.trgeo.2024.101395
Bowen Chen , Chengyu Liu , Qi Li , Chikezie Chimere Onyekwena
Subsurface settlement is often triggered by soil erosion above underground defective pipelines. However, there is currently insufficient research on calculation methods for estimating ground settlement caused by defective pipeline. In this work, a series of laboratory experiments were conducted to investigate the impacts of the soil particle size, hydraulic gradient, thick-span ratio, and full pipe flow velocity on ground settlement around submerged defective pipelines. A sensitivity analysis was performed to further examine these factors. The experimental results revealed that there are three settlement modes, primarily determined by soil skeleton particle size and the thick-span ratio. The full pipe flow velocity and hydraulic gradient significantly affected the settlement range, with the settlement range increasing as either the flow velocity or hydraulic gradient increased. Additionally, a new calculation model based on Manning’s equation was developed to predict soil settlement. The error between the calculation and experiment results was less than 15%, demonstrating the accuracy and effectiveness of the proposed method.
{"title":"Experimental and theoretical investigations of ground settlement around submerged defective pipelines","authors":"Bowen Chen , Chengyu Liu , Qi Li , Chikezie Chimere Onyekwena","doi":"10.1016/j.trgeo.2024.101395","DOIUrl":"10.1016/j.trgeo.2024.101395","url":null,"abstract":"<div><div>Subsurface settlement is often triggered by soil erosion above underground defective pipelines. However, there is currently insufficient research on calculation methods for estimating ground settlement caused by defective pipeline. In this work, a series of laboratory experiments were conducted to investigate the impacts of the soil particle size, hydraulic gradient, thick-span ratio, and full pipe flow velocity on ground settlement around submerged defective pipelines. A sensitivity analysis was performed to further examine these factors. The experimental results revealed that there are three settlement modes, primarily determined by soil skeleton particle size and the thick-span ratio<em>.</em> The full pipe flow velocity and hydraulic gradient significantly affected the settlement range, with the settlement range increasing as either the flow velocity or hydraulic gradient increased. Additionally, a new calculation model based on Manning’s equation was developed to predict soil settlement. The error between the calculation and experiment results was less than 15%, demonstrating the accuracy and effectiveness of the proposed method.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101395"},"PeriodicalIF":4.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434014","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}
Pub Date : 2024-10-01DOI: 10.1016/j.trgeo.2024.101392
Caijin Wang , Liangfu Xie , Zhiming Liu , Meng Wu , Tao Zhang , Guojun Cai , Songyu Liu
In the reconstruction and expansion of expressways in soft soil areas, controlling the differential settlement between the new and existing subgrades is of vital importance. To investigate the settlement and deformation characteristics of both the new and existing subgrades, piezocone penetration test (CPTU) and dissipation tests were conducted on these subgrades. The CPTU dissipation data was utilized to determine the soil’s degree of consolidation, and settlement calculations for the new and existing road subgrades were based on the CPTU test results. Subsequently, a finite element model was developed using the CPTU test findings to analyze the horizontal displacements, vertical settlements, and differential settlements of the new and existing subgrades before and after the reconstruction and expansion. Based on the measured settlement results, the new and old subgrade settlement calculation results are verified. The outcomes revealed that the degree of consolidation for the existing road subgrade of the Lianhuai Expressway ranged between 42 % and 96 %. The maximum horizontal displacement of the subgrade pre- and post-expansion occurred at the slope toe. Before expansion, the maximum vertical settlement was observed along the road’s centerline, while after expansion, it was located in the centerline of the widened section. The maximum additional settlement amounted to 274.77 mm. During the new road construction phase, the differential settlement between the new and existing road subgrades increased rapidly over time, peaking at its maximum value. However, during the operational phase of the new road, this differential settlement tapered off as time progressed.
{"title":"Study on settlement deformation law of new and old subgrade of expressway reconstruction and expansion based on CPTU","authors":"Caijin Wang , Liangfu Xie , Zhiming Liu , Meng Wu , Tao Zhang , Guojun Cai , Songyu Liu","doi":"10.1016/j.trgeo.2024.101392","DOIUrl":"10.1016/j.trgeo.2024.101392","url":null,"abstract":"<div><div>In the reconstruction and expansion of expressways in soft soil areas, controlling the differential settlement between the new and existing subgrades is of vital importance. To investigate the settlement and deformation characteristics of both the new and existing subgrades, piezocone penetration test (CPTU) and dissipation tests were conducted on these subgrades. The CPTU dissipation data was utilized to determine the soil’s degree of consolidation, and settlement calculations for the new and existing road subgrades were based on the CPTU test results. Subsequently, a finite element model was developed using the CPTU test findings to analyze the horizontal displacements, vertical settlements, and differential settlements of the new and existing subgrades before and after the reconstruction and expansion. Based on the measured settlement results, the new and old subgrade settlement calculation results are verified. The outcomes revealed that the degree of consolidation for the existing road subgrade of the Lianhuai Expressway ranged between 42 % and 96 %. The maximum horizontal displacement of the subgrade pre- and post-expansion occurred at the slope toe. Before expansion, the maximum vertical settlement was observed along the road’s centerline, while after expansion, it was located in the centerline of the widened section. The maximum additional settlement amounted to 274.77 mm. During the new road construction phase, the differential settlement between the new and existing road subgrades increased rapidly over time, peaking at its maximum value. However, during the operational phase of the new road, this differential settlement tapered off as time progressed.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101392"},"PeriodicalIF":4.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422793","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}
Pub Date : 2024-09-30DOI: 10.1016/j.trgeo.2024.101383
A. Jain, A.V. Metrikine, K.N. van Dalen
Railway transition zones are critical regions in railway infrastructure that are subjected to excessive operation-driven degradation due to energy concentration within these zones. This work presents a heuristic approach to optimise the geometry of the transition structure and investigate its influence on the strain energy distribution in the railway transition zones (RTZs), with a specific focus on embankment-bridge transitions equipped with a newly proposed ’Safe Hull-Inspired Energy Limiting Design (SHIELD)’ transition structure. For this purpose, a number of three-dimensional finite element models are used to analyze different geometric profiles of SHIELD in a systematic manner. By altering SHIELD’s geometry across longitudinal, transversal, and vertical directions, the influence of the different geometric profiles on the total strain energy distribution across the trackbed layers (ballast, embankment, and subgrade) is studied in terms of spatial and temporal variations. The results establish the contribution of geometry to energy redistribution in all three directions and present an optimum geometry for the type of transition under study. It is found that among all the profiles, the longitudinal geometric profile of SHIELD has the most significant impact on the strain energy distribution, while the transversal profile primarily influences the ballast layer, and the alteration of vertical profiles enhance the local redistribution of strain energy in the vicinity of the transition interface. The preliminary optimisation (heuristic approach) presented in this work provides the starting point for full-scale optimisation to obtain tailored shapes of transition structures such that there is neither a concentration of energy nor an obstruction in the flow of energy in RTZs.
{"title":"Energy redistribution in railway transition zones by geometric optimisation of a novel transition structure","authors":"A. Jain, A.V. Metrikine, K.N. van Dalen","doi":"10.1016/j.trgeo.2024.101383","DOIUrl":"10.1016/j.trgeo.2024.101383","url":null,"abstract":"<div><div>Railway transition zones are critical regions in railway infrastructure that are subjected to excessive operation-driven degradation due to energy concentration within these zones. This work presents a heuristic approach to optimise the geometry of the transition structure and investigate its influence on the strain energy distribution in the railway transition zones (RTZs), with a specific focus on embankment-bridge transitions equipped with a newly proposed ’Safe Hull-Inspired Energy Limiting Design (SHIELD)’ transition structure. For this purpose, a number of three-dimensional finite element models are used to analyze different geometric profiles of SHIELD in a systematic manner. By altering SHIELD’s geometry across longitudinal, transversal, and vertical directions, the influence of the different geometric profiles on the total strain energy distribution across the trackbed layers (ballast, embankment, and subgrade) is studied in terms of spatial and temporal variations. The results establish the contribution of geometry to energy redistribution in all three directions and present an optimum geometry for the type of transition under study. It is found that among all the profiles, the longitudinal geometric profile of SHIELD has the most significant impact on the strain energy distribution, while the transversal profile primarily influences the ballast layer, and the alteration of vertical profiles enhance the local redistribution of strain energy in the vicinity of the transition interface. The preliminary optimisation (heuristic approach) presented in this work provides the starting point for full-scale optimisation to obtain tailored shapes of transition structures such that there is neither a concentration of energy nor an obstruction in the flow of energy in RTZs.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101383"},"PeriodicalIF":4.9,"publicationDate":"2024-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142446688","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}
Pub Date : 2024-09-29DOI: 10.1016/j.trgeo.2024.101393
Karol Brzeziński , Paweł Ciężkowski , Kazimierz Józefiak , Sebastian Bąk , Rafał Michalczyk , Arkadiusz Kwaśniewski
In this study, compaction tests on three soil types (glacial aggregate mixture, amphibolite aggregate and sand-gravel mixture) were conducted in a full-scale plate compactor experiment under different frequency scenarios, specifically between 74 and 84 Hz. The experimental approach included measuring bulk density through photogrammetry and soil sampling at different layer depths. This methodology enabled the direct assessment of Relative Compaction (RC). Furthermore, soil stiffness was measured during compaction via a lightweight dynamic plate. Findings revealed that lower compaction frequencies generally resulted in denser compaction near the surface, while higher frequencies improved compaction at greater depths. Additionally, the study explored the relationship between dynamic modulus and RC. The study highlights the need for advanced, rapid compaction assessment methods, given the limitations of current techniques. The results indicate that within the analyzed range of compaction frequencies, both the dynamic modulus and RC requirements are achieved after the same number of compactor passes, regardless of the selected frequency scenario. Therefore, opting for a lower frequency can reduce fuel consumption and equipment wear while maintaining compaction objectives, leading to better overall efficiency.
{"title":"Enhancing plate compactor efficiency: A study on frequency effects for different soil types","authors":"Karol Brzeziński , Paweł Ciężkowski , Kazimierz Józefiak , Sebastian Bąk , Rafał Michalczyk , Arkadiusz Kwaśniewski","doi":"10.1016/j.trgeo.2024.101393","DOIUrl":"10.1016/j.trgeo.2024.101393","url":null,"abstract":"<div><div>In this study, compaction tests on three soil types (glacial aggregate mixture, amphibolite aggregate and sand-gravel mixture) were conducted in a full-scale plate compactor experiment under different frequency scenarios, specifically between 74 and 84 Hz. The experimental approach included measuring bulk density through photogrammetry and soil sampling at different layer depths. This methodology enabled the direct assessment of Relative Compaction (RC). Furthermore, soil stiffness was measured during compaction via a lightweight dynamic plate. Findings revealed that lower compaction frequencies generally resulted in denser compaction near the surface, while higher frequencies improved compaction at greater depths. Additionally, the study explored the relationship between dynamic modulus and RC. The study highlights the need for advanced, rapid compaction assessment methods, given the limitations of current techniques. The results indicate that within the analyzed range of compaction frequencies, both the dynamic modulus and RC requirements are achieved after the same number of compactor passes, regardless of the selected frequency scenario. Therefore, opting for a lower frequency can reduce fuel consumption and equipment wear while maintaining compaction objectives, leading to better overall efficiency.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101393"},"PeriodicalIF":4.9,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422884","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}
Pub Date : 2024-09-27DOI: 10.1016/j.trgeo.2024.101391
Kangjian Zhang, Zhiqiang Zhang, Qingnan Lan
The combined effects of dynamic loads from high-speed trains and surrounding soil expansion pressure often lead to structure failure in tunnels during their service period. This study conducts a series of expansion pressure, expansion rate, and shear strength tests on expansive soil to analyze the impact of the initial moisture content and dry density on expansion behaviors. The results indicate that the expansion pressure is negatively (positively) correlated with the initial moisture content (dry density). The expansion rate decreases with increasing vertical pressure and initial moisture content. The expansive soil’s shear strength, internal friction angle, and cohesion are approximately linearly negatively correlated with initial moisture content. A three-dimensional dynamic computational model combining the train dynamic load, surrounding soil, and lining structure is established to study the tunnel’s dynamic responses and long-term damage evolution. The simulation results indicate that the combined effects of high-speed train dynamic loads and expansion pressure cause the tunnel’s maximum vertical acceleration and vertical displacement response to occur at the center of the invert. In contrast, the maximum peak of the minimum principal stress response occurs near the invert beneath the track. The minimum responses of the acceleration, vertical displacement, and peak of the minimum principal stress occur at the roof, hance, and wall, respectively. The tunnel’s vertical acceleration, vertical displacement, and peak minimum principal stress are positively correlated with expansion pressure (or train speed). When the train speed is below 300 km/h, changes in the expansion pressure (or train speed) do not alter the shape of the response envelope diagram or the relative intensity of the response at each measuring point. The upper structure of the tunnel (above the wall) experiences little damage, which is concentrated primarily in the invert and both side feet of the tunnel. Tensile damage is greater than compression damage, and the expansion pressure significantly affects the rate of damage development in tunnels during the first 15 years of service.
{"title":"Dynamic responses and long-term damage evolution of tunnels in expansive strata under dynamic loads from high-speed trains","authors":"Kangjian Zhang, Zhiqiang Zhang, Qingnan Lan","doi":"10.1016/j.trgeo.2024.101391","DOIUrl":"10.1016/j.trgeo.2024.101391","url":null,"abstract":"<div><div>The combined effects of dynamic loads from high-speed trains and surrounding soil expansion pressure often lead to structure failure in tunnels during their service period. This study conducts a series of expansion pressure, expansion rate, and shear strength tests on expansive soil to analyze the impact of the initial moisture content and dry density on expansion behaviors. The results indicate that the expansion pressure is negatively (positively) correlated with the initial moisture content (dry density). The expansion rate decreases with increasing vertical pressure and initial moisture content. The expansive soil’s shear strength, internal friction angle, and cohesion are approximately linearly negatively correlated with initial moisture content. A three-dimensional dynamic computational model combining the train dynamic load, surrounding soil, and lining structure is established to study the tunnel’s dynamic responses and long-term damage evolution. The simulation results indicate that the combined effects of high-speed train dynamic loads and expansion pressure cause the tunnel’s maximum vertical acceleration and vertical displacement response to occur at the center of the invert. In contrast, the maximum peak of the minimum principal stress response occurs near the invert beneath the track. The minimum responses of the acceleration, vertical displacement, and peak of the minimum principal stress occur at the roof, hance, and wall, respectively. The tunnel’s vertical acceleration, vertical displacement, and peak minimum principal stress are positively correlated with expansion pressure (or train speed). When the train speed is below 300 km/h, changes in the expansion pressure (or train speed) do not alter the shape of the response envelope diagram or the relative intensity of the response at each measuring point. The upper structure of the tunnel (above the wall) experiences little damage, which is concentrated primarily in the invert and both side feet of the tunnel. Tensile damage is greater than compression damage, and the expansion pressure significantly affects the rate of damage development in tunnels during the first 15 years of service.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101391"},"PeriodicalIF":4.9,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422890","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}
Pub Date : 2024-09-26DOI: 10.1016/j.trgeo.2024.101390
Dong Ding , Jiale Xie , Yong Wang , Guoqing Jing
This study investigates the impact of sand contamination on the mechanical properties of railway ballasted tracks in confined condition. A combination of experimental confined uniaxial compression tests and discrete element method (DEM) simulations was employed. The experiments assessed the bulk density and elastic modulus of ballast aggregates, while the DEM simulations focused on sand movement, coordination numbers, and contact forces to elucidate the mesoscopic behavior. Findings from both experiments and simulations consistently demonstrate that sand contamination linearly increases the bulk density and causes a non-linear increase in the elastic modulus of ballast aggregates. With increasing degrees of sand contamination under vertical loading, both coordination numbers and contact forces are reduced. Sand intrusion initially leads to an uneven distribution of sand grains, primarily in the lower layer of the ballast aggregate; however, this distribution becomes more uniform when contamination exceeds 62.5%. The presence of sand particles diminishes the contact forces between ballast particles, thereby escalating the challenges associated with maintenance and repair.
{"title":"Experimental and numerical study on mechanical properties of sand-contaminated ballast aggregates in confined condition","authors":"Dong Ding , Jiale Xie , Yong Wang , Guoqing Jing","doi":"10.1016/j.trgeo.2024.101390","DOIUrl":"10.1016/j.trgeo.2024.101390","url":null,"abstract":"<div><div>This study investigates the impact of sand contamination on the mechanical properties of railway ballasted tracks in confined condition. A combination of experimental confined uniaxial compression tests and discrete element method (DEM) simulations was employed. The experiments assessed the bulk density and elastic modulus of ballast aggregates, while the DEM simulations focused on sand movement, coordination numbers, and contact forces to elucidate the mesoscopic behavior. Findings from both experiments and simulations consistently demonstrate that sand contamination linearly increases the bulk density and causes a non-linear increase in the elastic modulus of ballast aggregates. With increasing degrees of sand contamination under vertical loading, both coordination numbers and contact forces are reduced. Sand intrusion initially leads to an uneven distribution of sand grains, primarily in the lower layer of the ballast aggregate; however, this distribution becomes more uniform when contamination exceeds 62.5%. The presence of sand particles diminishes the contact forces between ballast particles, thereby escalating the challenges associated with maintenance and repair.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101390"},"PeriodicalIF":4.9,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142356640","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}
Pub Date : 2024-09-26DOI: 10.1016/j.trgeo.2024.101388
M.S.K. Hassan, D.S. Liyanapathirana, W. Fuentes, C.J. Leo, P. Hu
Integral bridges have been proposed as a jointless design alternative to the traditional counterparts, possessing copious potential economic and structural advantages. However, due to the monolithic connection at the girder-abutment interface, longitudinal deformations from the superstructure must now be accommodated by the stiffness of the approach backfill and soil surrounding the foundation. Consequently, in addition to traffic loads, integral bridge approaches are subjected to long-term, cyclic loading due to diurnal and seasonal thermal variations. This has resulted in two progressive geotechnical phenomena: an escalation of lateral passive pressures at the abutment-soil interface and accumulated deformations near the bridge approach. Over the last two decades, several investigations on the approach backfill-abutment interaction have been carried out. However, previous reviews on integral bridges have not comprehensively discussed the theoretical aspects of these two complex geotechnical issues. Hence, this paper presents a discussion on the long-term response of stress ratcheting observed from controlled analyses, along with a comparison to that from field monitoring data. Subsequently, the occurrence of accumulated deformations, along with a correlation to the mechanism of the cyclic interaction is explored. The effects of foundation design choice and skew angle on the passive pressure accumulation and soil deformation behavior are then presented. Subsequently, approaches used to mitigate the effects of the backfill-abutment interaction are compared. From this review, it is apparent that outcomes based on available experimental and field investigations are yet inadequate to develop analytical models required to predict the long-term response of integral bridge approach backfills under various loading conditions.
{"title":"A review of soil deformation and lateral pressure ratcheting phenomena in integral abutment bridges","authors":"M.S.K. Hassan, D.S. Liyanapathirana, W. Fuentes, C.J. Leo, P. Hu","doi":"10.1016/j.trgeo.2024.101388","DOIUrl":"10.1016/j.trgeo.2024.101388","url":null,"abstract":"<div><div>Integral bridges have been proposed as a jointless design alternative to the traditional counterparts, possessing copious potential economic and structural advantages. However, due to the monolithic connection at the girder-abutment interface, longitudinal deformations from the superstructure must now be accommodated by the stiffness of the approach backfill and soil surrounding the foundation. Consequently, in addition to traffic loads, integral bridge approaches are subjected to long-term, cyclic loading due to diurnal and seasonal thermal variations. This has resulted in two progressive geotechnical phenomena: an escalation of lateral passive pressures at the abutment-soil interface and accumulated deformations near the bridge approach. Over the last two decades, several investigations on the approach backfill-abutment interaction have been carried out. However, previous reviews on integral bridges have not comprehensively discussed the theoretical aspects of these two complex geotechnical issues. Hence, this paper presents a discussion on the long-term response of stress ratcheting observed from controlled analyses, along with a comparison to that from field monitoring data. Subsequently, the occurrence of accumulated deformations, along with a correlation to the mechanism of the cyclic interaction is explored. The effects of foundation design choice and skew angle on the passive pressure accumulation and soil deformation behavior are then presented. Subsequently, approaches used to mitigate the effects of the backfill-abutment interaction are compared. From this review, it is apparent that outcomes based on available experimental and field investigations are yet inadequate to develop analytical models required to predict the long-term response of integral bridge approach backfills under various loading conditions.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101388"},"PeriodicalIF":4.9,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422794","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}
The compacted dry density of gravelly soils containing particles that are too large for ordinary laboratory compaction tests is usually estimated by measuring the dry density of the base sample obtained by removing over-sized particles then correcting the measured value by the Walker-Holtz Equation (W&H Eq.). It is known that the W&H Eq. overestimates the dry density of gravelly soils and this trend becomes stronger as the mass ratio P of oversized particles increases. It seems that a satisfactory solution is not yet available. A comprehensive series of laboratory compaction tests was performed on a wide variety of gravelly soil samples with different particle sizes, grading uniformities and particle shapes. The followings were found. The ratio, X, of the maximum dry density predicted by the W&H Eq. to the measured value increases linearly from unity as P increases from zero up to approximately 0.75. The slope of the X-P relation, (X − 1.0) / P, increases as the coefficient of uniformity or the fines content of the base sample increases and as the gravel particles become more angular in a synergistic manner. It is proposed to estimate the maximum dry density of compacted gravelly soil containing oversized particles by dividing the value predicted from the W&H Eq. by X obtained from the substitution of P into the relevant X-P relation. Proposed based on the above is an effective and efficient compaction method for gravelly soils containing oversized particles that controls the degree of saturation and the compaction energy.
砾质土壤中的颗粒过大，无法进行普通的实验室压实试验，通常通过测量去除过大颗粒后获得的基底样本的干密度，然后用沃克-霍兹方程（W&H Eq.）对测量值进行修正，从而估算出砾质土壤的压实干密度。众所周知，W&H 公式会高估砾质土壤的干密度，而且随着超大颗粒质量比 P 的增加，这种趋势会越来越明显。目前似乎还没有令人满意的解决方案。对各种不同粒径、级配均匀度和颗粒形状的砾质土样本进行了一系列全面的实验室压实试验。结果如下W&H 公式预测的最大干密度与测量值的比值 X，随着 P 从零增加到约 0.75，从统一值线性增加。X-P 关系的斜率 (X - 1.0) / P 会随着基样均匀系数或细粒含量的增加以及砾石颗粒在协同作用下变得更有棱角而增加。建议将 W&H 公式的预测值除以将 P 代入相关 X-P 关系中得到的 X，从而估算出含有过大颗粒的压实砾质土的最大干密度。根据上述方法，我们提出了一种有效且高效的压实方法，用于含有过大颗粒的砾质土壤，该方法可控制饱和度和压实能量。
{"title":"Estimating the compacted dry density of gravelly soil with oversized particles","authors":"Sou Ihara , Sakino Furuhata , Shohei Noda , Hiroyuki Nagai , Yoshiaki Kikuchi , Fumio Tatsuoka","doi":"10.1016/j.trgeo.2024.101379","DOIUrl":"10.1016/j.trgeo.2024.101379","url":null,"abstract":"<div><div>The compacted dry density of gravelly soils containing particles that are too large for ordinary laboratory compaction tests is usually estimated by measuring the dry density of the base sample obtained by removing over-sized particles then correcting the measured value by the Walker-Holtz Equation (W&H Eq.). It is known that the W&H Eq. overestimates the dry density of gravelly soils and this trend becomes stronger as the mass ratio <em>P</em> of oversized particles increases. It seems that a satisfactory solution is not yet available. A comprehensive series of laboratory compaction tests was performed on a wide variety of gravelly soil samples with different particle sizes, grading uniformities and particle shapes. The followings were found. The ratio, <em>X</em>, of the maximum dry density predicted by the W&H Eq. to the measured value increases linearly from unity as <em>P</em> increases from zero up to approximately 0.75. The slope of the <em>X</em>-<em>P</em> relation, (<em>X</em> − 1.0) / <em>P</em>, increases as the coefficient of uniformity or the fines content of the base sample increases and as the gravel particles become more angular in a synergistic manner. It is proposed to estimate the maximum dry density of compacted gravelly soil containing oversized particles by dividing the value predicted from the W&H Eq. by <em>X</em> obtained from the substitution of <em>P</em> into the relevant <em>X</em>-<em>P</em> relation. Proposed based on the above is an effective and efficient compaction method for gravelly soils containing oversized particles that controls the degree of saturation and the compaction energy.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101379"},"PeriodicalIF":4.9,"publicationDate":"2024-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142422800","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}
Pub Date : 2024-09-24DOI: 10.1016/j.trgeo.2024.101389
Shuxin Zhao , Yanglong Zhong , Liang Gao , Zhihan Zhang , Shunwei Shi , Weitao Cui
Excessive railway tunnel floor heave (TFH) will reduce the durability of the track structure and jeopardize train operation safety. The TFH characteristics were fitted into cosine and bilinear curves according to the monitoring data. A nonlinear failure analysis model of double-block ballastless track under TFH was established. The deformation transfer law, structural damage mechanism and the interlayer bonding interface failure evolution of the track structure under different TFH characteristics were explored. The results show that the deformation of TFH can be well mapped to the track. The amplitude transfer ratio is less than 100 %. The maximum wavelength transfer ratio under the cosine and bilinear TFH is 129.3 % and 127.5 %, respectively. To avoid the damage of track structure, when the wavelength is 10 m, the amplitude of cosine and bilinear TFH should be controlled at 2.5 mm and 0.5 mm respectively. When the wavelength is greater than 10 m, the amplitude can be appropriately increased. To avoid interlayer bonding cracking, the cosine and bilinear amplitudes with a wavelength of 10 m should be controlled at 5 mm and 1.5 mm, respectively. The track-tunnel interlayer debonding failure under the cosine curve occurs at the edge of the TFH, while the bilinear curve occurs at the center and edge of the TFH. The gaps under the cosine and bilinear TFH exhibit double-peak and multi-peak shapes, respectively. This study can provide theoretical guidance for controlling the performance degradation of track structure caused by TFH.
{"title":"Research on damage characteristics and contact interface evolution behavior of double-block ballastless track considering tunnel floor heave","authors":"Shuxin Zhao , Yanglong Zhong , Liang Gao , Zhihan Zhang , Shunwei Shi , Weitao Cui","doi":"10.1016/j.trgeo.2024.101389","DOIUrl":"10.1016/j.trgeo.2024.101389","url":null,"abstract":"<div><div>Excessive railway tunnel floor heave (TFH) will reduce the durability of the track structure and jeopardize train operation safety. The TFH characteristics were fitted into cosine and bilinear curves according to the monitoring data. A nonlinear failure analysis model of double-block ballastless track under TFH was established. The deformation transfer law, structural damage mechanism and the interlayer bonding interface failure evolution of the track structure under different TFH characteristics were explored. The results show that the deformation of TFH can be well mapped to the track. The amplitude transfer ratio is less than 100 %. The maximum wavelength transfer ratio under the cosine and bilinear TFH is 129.3 % and 127.5 %, respectively. To avoid the damage of track structure, when the wavelength is 10 m, the amplitude of cosine and bilinear TFH should be controlled at 2.5 mm and 0.5 mm respectively. When the wavelength is greater than 10 m, the amplitude can be appropriately increased. To avoid interlayer bonding cracking, the cosine and bilinear amplitudes with a wavelength of 10 m should be controlled at 5 mm and 1.5 mm, respectively. The track-tunnel interlayer debonding failure under the cosine curve occurs at the edge of the TFH, while the bilinear curve occurs at the center and edge of the TFH. The gaps under the cosine and bilinear TFH exhibit double-peak and multi-peak shapes, respectively. This study can provide theoretical guidance for controlling the performance degradation of track structure caused by TFH.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101389"},"PeriodicalIF":4.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142327340","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}
During the excavation of rock tunnels, accurately understanding the structural characteristics of the tunnel face is crucial for ensuring construction safety. The study evaluates the structural characteristics of the tunnel face by precisely characterizing and analyzing parameters like fracture trace length and dip angle, aiming to calculate the degree of fragmentation and potential sliding zones of the rock mass. In evaluating rock fragmentation degree, the study identifies and quantifies fracture trace lengths as a single-factor indicator to assess the fragmentation of the rock mass on the working face. By comparing with the p21 index, the reliability and reasonableness of the rock fragmentation evaluation are discussed. For the evaluation of potential sliding zones, a method for approximating the extraction of fracture traces is proposed. The assessment is then conducted based on multi-factor indicators, including fracture dip angle and length. Additionally, the advantages and disadvantages of various indicators under different calculation methods are discussed. The study finds that rock fragmentation indicators offer a more detailed and accurate description of the actual fracture density of the rock mass compared to the P21 index, proving to be generally more reliable under extreme conditions. Furthermore, the evaluation of rock fragmentation and potential sliding zones on the rock face can provide important references for the refined extraction of rock mass structural characteristics, ensuring the safe construction of tunnels.
{"title":"Assessing fragmentation and potential sliding zones in rock tunnels via computer vision technology","authors":"Yifan Shen , Jiayao Chen , Qian Fang , Dingli Zhang , Hongwei Huang , Yajian Shu","doi":"10.1016/j.trgeo.2024.101384","DOIUrl":"10.1016/j.trgeo.2024.101384","url":null,"abstract":"<div><div>During the excavation of rock tunnels, accurately understanding the structural characteristics of the tunnel face is crucial for ensuring construction safety. The study evaluates the structural characteristics of the tunnel face by precisely characterizing and analyzing parameters like fracture trace length and dip angle, aiming to calculate the degree of fragmentation and potential sliding zones of the rock mass. In evaluating rock fragmentation degree, the study identifies and quantifies fracture trace lengths as a single-factor indicator to assess the fragmentation of the rock mass on the working face. By comparing with the p21 index, the reliability and reasonableness of the rock fragmentation evaluation are discussed. For the evaluation of potential sliding zones, a method for approximating the extraction of fracture traces is proposed. The assessment is then conducted based on multi-factor indicators, including fracture dip angle and length. Additionally, the advantages and disadvantages of various indicators under different calculation methods are discussed. The study finds that rock fragmentation indicators offer a more detailed and accurate description of the actual fracture density of the rock mass compared to the P21 index, proving to be generally more reliable under extreme conditions. Furthermore, the evaluation of rock fragmentation and potential sliding zones on the rock face can provide important references for the refined extraction of rock mass structural characteristics, ensuring the safe construction of tunnels.</div></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":"49 ","pages":"Article 101384"},"PeriodicalIF":4.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142356643","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}
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