Vacuum preloading and composite ground reinforcement are commonly used methods for reinforcing soft soil, but there is a lack of integrated design method for vacuum preloading combined with composite ground. This case study introduces an innovative approach that combines vacuum preloading with liquid bag pressurization to achieve the integrated design of consolidation drainage method and composite ground reinforcement, which is different from the reported air bag pressurization. To illustrate the effectiveness of this method. Model tests were carried out to analyze the variation of water discharge, pore water pressure, ground settlement, and average consolidation degree in the process of vacuum consolidation. The study investigated the water content, undrained shear strength and ground bearing capacity of composite ground after ground treatment. A correlation between average undrained shear strength and characteristic value of ground-bearing capacity was established to evaluate and predict the treatment effect of composite ground. Research shows that compared with traditional vacuum preloading, the undrained shear strength can be increased by 13.78%~65.08%, and the characteristic value of bearing capacity for the composite ground can be enlarged by 2.3-4 times. These results indicate that the vacuum preloading combined with liquid bag pressurization can significantly improve reinforcement effect on soft ground.
{"title":"Physical model case study: treatment effect of soft ground by vacuum preloading combined with liquid bag pressurization method","authors":"Shuangxi Feng, Daorun Xing, Huayang Lei, Rui Jia, Jiankai Li, Coffi Edgard Codjia, Yilin Bao","doi":"10.1139/cgj-2023-0393","DOIUrl":"https://doi.org/10.1139/cgj-2023-0393","url":null,"abstract":"Vacuum preloading and composite ground reinforcement are commonly used methods for reinforcing soft soil, but there is a lack of integrated design method for vacuum preloading combined with composite ground. This case study introduces an innovative approach that combines vacuum preloading with liquid bag pressurization to achieve the integrated design of consolidation drainage method and composite ground reinforcement, which is different from the reported air bag pressurization. To illustrate the effectiveness of this method. Model tests were carried out to analyze the variation of water discharge, pore water pressure, ground settlement, and average consolidation degree in the process of vacuum consolidation. The study investigated the water content, undrained shear strength and ground bearing capacity of composite ground after ground treatment. A correlation between average undrained shear strength and characteristic value of ground-bearing capacity was established to evaluate and predict the treatment effect of composite ground. Research shows that compared with traditional vacuum preloading, the undrained shear strength can be increased by 13.78%~65.08%, and the characteristic value of bearing capacity for the composite ground can be enlarged by 2.3-4 times. These results indicate that the vacuum preloading combined with liquid bag pressurization can significantly improve reinforcement effect on soft ground.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"27 24","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141924914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peak strength and dilatancy of granular materials generally decrease with increasing mean effective stress, and such a decrease will be enhanced due to the occurrence of particle breakage. This paper presents a simple empirical approach to modify Bolton’s original strength and dilatancy equation for crushable soils with different crushability. The proposed approach is based on data of a series of drained triaxial tests on carbonate soils with five different particle size distributions (PSDs) and three initial relative densities. It is also validated against other published experimental data on various crushable soils, including carbonate soils, limestones, coarse aggregates, and silica sands. The modified relation retains a similar form to Bolton’s equation with only one additional parameter introduced. As a result, the crushing strength-related parameter in the original relation is modified to incorporate the impacts of particle shape, gradings, and mineralogy on particle breakage. This modified parameter tends to increase as soil crushability decreases, which keeps a similar physical meaning to Bolton’s crushing strength-related parameter, and is suitable for a wider range of crushable soils with different gradings. The proposed strength and dilatancy equation for crushable soils yields to Bolton’s equation for strong soil particles where particle breakage is negligible.
{"title":"Strength and Dilatancy of Crushable Soils With Different Gradings","authors":"Zong-Lei Dong, Chenxi Tong, Sheng Zhang, Yi Pik Cheng, Daichao Sheng","doi":"10.1139/cgj-2023-0554","DOIUrl":"https://doi.org/10.1139/cgj-2023-0554","url":null,"abstract":"Peak strength and dilatancy of granular materials generally decrease with increasing mean effective stress, and such a decrease will be enhanced due to the occurrence of particle breakage. This paper presents a simple empirical approach to modify Bolton’s original strength and dilatancy equation for crushable soils with different crushability. The proposed approach is based on data of a series of drained triaxial tests on carbonate soils with five different particle size distributions (PSDs) and three initial relative densities. It is also validated against other published experimental data on various crushable soils, including carbonate soils, limestones, coarse aggregates, and silica sands. The modified relation retains a similar form to Bolton’s equation with only one additional parameter introduced. As a result, the crushing strength-related parameter in the original relation is modified to incorporate the impacts of particle shape, gradings, and mineralogy on particle breakage. This modified parameter tends to increase as soil crushability decreases, which keeps a similar physical meaning to Bolton’s crushing strength-related parameter, and is suitable for a wider range of crushable soils with different gradings. The proposed strength and dilatancy equation for crushable soils yields to Bolton’s equation for strong soil particles where particle breakage is negligible.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"5 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141921392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study conducts a thorough numerical analysis on the pullout capacity of suction caissons in sand-over-clay deposits. A validated finite element (FE) model is used and verified against available centrifuge experiments and numerical results. A parametric analysis is then performed to investigate the factors influencing the suction caisson’s pullout capacity, including caisson’s length, pad-eye position, and layered deposits. The FE outcomes provide insights into the following key design components: (i) the optimal pad-eye locations; (ii) the ultimate horizontal and vertical bearing capacities; and (iii) the horizontal load estimation at various pad-eyes attachments. A straightforward guideline for calculating the caisson’s pullout capacities is then established for preliminary estimations for suction caissons in silty sand-over-clay deposit.
{"title":"Numerical investigation on the pullout capacity of suction caissons in silty sand-over-clay deposit","authors":"Ningxin Yang, Mi Zhou, Yinghui Tian, Xihong Zhang","doi":"10.1139/cgj-2023-0555","DOIUrl":"https://doi.org/10.1139/cgj-2023-0555","url":null,"abstract":"This study conducts a thorough numerical analysis on the pullout capacity of suction caissons in sand-over-clay deposits. A validated finite element (FE) model is used and verified against available centrifuge experiments and numerical results. A parametric analysis is then performed to investigate the factors influencing the suction caisson’s pullout capacity, including caisson’s length, pad-eye position, and layered deposits. The FE outcomes provide insights into the following key design components: (i) the optimal pad-eye locations; (ii) the ultimate horizontal and vertical bearing capacities; and (iii) the horizontal load estimation at various pad-eyes attachments. A straightforward guideline for calculating the caisson’s pullout capacities is then established for preliminary estimations for suction caissons in silty sand-over-clay deposit.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"60 17","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929229","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Antonio M. L. Alves, B. Danziger, Francisco R. Lopes
{"title":"Discussion of “Investigation of soil setup effects on pile response in clay considering over-consolidation ratio and installation method through physical modeling”","authors":"Antonio M. L. Alves, B. Danziger, Francisco R. Lopes","doi":"10.1139/cgj-2023-0754","DOIUrl":"https://doi.org/10.1139/cgj-2023-0754","url":null,"abstract":"","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"11 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927493","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Three-dimensional (3D) geological modelling enhances the understanding and visualisation of complex subsurface stratigraphy, which underpins geotechnical digital twin and resilience design. Existing methods for 3D geological modelling suffer from either high computational burden or low modelling accuracy in large-scale region modelling with complex subsurface stratigraphy. This paper presents a novel deep learning method that applies the graph convolutional network (GCN) to 3D voxel geological modelling using limited boreholes. A topological graph is firstly constructed, with spatial points encoded as graph nodes. The strata types and spatial coordinates are incorporated into the feature vector of each node. Spatial correlations are quantified through weighted edges by connecting pairs of nodes within a cuboid neighbouring system. Besides, the occurrence probability of strata in all boreholes is embedded into the feature vector of each graph node to further improve the model robustness. A series of comparisons shows that the proposed method outperforms traditional TPS and MPS methods in terms of modelling accuracy. The proposed method is finally applied to a real tunnel engineering in Changsha City, which demonstrates the effectiveness of the proposed method in complex 3D geological settings.
{"title":"Three-dimensional voxel geological modelling for subsurface stratigraphy: A graph convolutional network approach","authors":"Lai Wang, Qiujing Pan, Shan Huang, Dong Su","doi":"10.1139/cgj-2024-0191","DOIUrl":"https://doi.org/10.1139/cgj-2024-0191","url":null,"abstract":"Three-dimensional (3D) geological modelling enhances the understanding and visualisation of complex subsurface stratigraphy, which underpins geotechnical digital twin and resilience design. Existing methods for 3D geological modelling suffer from either high computational burden or low modelling accuracy in large-scale region modelling with complex subsurface stratigraphy. This paper presents a novel deep learning method that applies the graph convolutional network (GCN) to 3D voxel geological modelling using limited boreholes. A topological graph is firstly constructed, with spatial points encoded as graph nodes. The strata types and spatial coordinates are incorporated into the feature vector of each node. Spatial correlations are quantified through weighted edges by connecting pairs of nodes within a cuboid neighbouring system. Besides, the occurrence probability of strata in all boreholes is embedded into the feature vector of each graph node to further improve the model robustness. A series of comparisons shows that the proposed method outperforms traditional TPS and MPS methods in terms of modelling accuracy. The proposed method is finally applied to a real tunnel engineering in Changsha City, which demonstrates the effectiveness of the proposed method in complex 3D geological settings.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141799455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mouadh Rafai, A. Tang, Thibault Badinier, Jean de Sauvage, Diana Salciarini
Energy geostructures provide a profitable solution for structural support as well as the heating and cooling of buildings. However, their activation can produce in structure and its surrounding soil thermally-induced stresses and strains with a crucial role played by the soil-structure interface which is the thin layer that transmits the thermal and mechanical loads. In the present work, the thermo-mechanical behaviour of the soil–structure interface is investigated using a temperature-controlled direct shear box. Tests were conducted on loose and dense sands in contact with a concrete plate representing the structure's surface. After applying the normal stress (25, 50, or 100 kPa), a shear stress was increased up to 45% of the shear strength. This stress state was then maintained while 20 cycles of temperature varying between 13 °C and 34 °C at the soil-concrete interface were applied. The obtained experimental results reveal that temperature cycles lead to irreversible cumulative displacements in both normal and shear directions. These displacements were found to be more significant in loose sand compared to dense sand. Additionally, under higher stress levels, greater displacements were observed for both soil densities.
能源土工结构为结构支撑以及建筑物的供暖和制冷提供了一个有利的解决方案。然而，它们的激活会在结构及其周围土壤中产生热应力和应变，而土壤-结构界面是传递热负荷和机械负荷的薄层，起着至关重要的作用。在本研究中，使用温控直接剪切箱对土壤-结构界面的热机械性能进行了研究。试验在与代表结构表面的混凝土板接触的松散和致密砂土上进行。在施加法向应力（25、50 或 100 kPa）后，剪应力增加到剪切强度的 45%。然后保持这种应力状态，同时在土壤-混凝土界面上施加 20 个温度周期，温度在 13 °C 和 34 °C 之间变化。实验结果表明，温度循环会导致法向和剪切方向的不可逆累积位移。这些位移在松散砂土中比在致密砂土中更为显著。此外，在较高应力水平下，两种密度的土壤都出现了较大的位移。
{"title":"Effect of thermal cycles on sand-concrete interface under constant shear stress","authors":"Mouadh Rafai, A. Tang, Thibault Badinier, Jean de Sauvage, Diana Salciarini","doi":"10.1139/cgj-2023-0140","DOIUrl":"https://doi.org/10.1139/cgj-2023-0140","url":null,"abstract":"Energy geostructures provide a profitable solution for structural support as well as the heating and cooling of buildings. However, their activation can produce in structure and its surrounding soil thermally-induced stresses and strains with a crucial role played by the soil-structure interface which is the thin layer that transmits the thermal and mechanical loads. In the present work, the thermo-mechanical behaviour of the soil–structure interface is investigated using a temperature-controlled direct shear box. Tests were conducted on loose and dense sands in contact with a concrete plate representing the structure's surface. After applying the normal stress (25, 50, or 100 kPa), a shear stress was increased up to 45% of the shear strength. This stress state was then maintained while 20 cycles of temperature varying between 13 °C and 34 °C at the soil-concrete interface were applied. The obtained experimental results reveal that temperature cycles lead to irreversible cumulative displacements in both normal and shear directions. These displacements were found to be more significant in loose sand compared to dense sand. Additionally, under higher stress levels, greater displacements were observed for both soil densities.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"21 6","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141801665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The small-strain shear modulus and shear strength are mechanical parameters crucial in the design of geotechnical structures and in the analyses of soil-structure interactions. This paper proposes a new approach for estimating these mechanical parameters. The proposed approach is predicated on the proportional inverse relationship of mechanical soil properties to the soil-water characteristic curve (SWCC). The proposed equations supporting the approach incorporate a scaling function, alongside the initial saturated mechanical property. The performance of the proposed equations was demonstrated across a variety of soil textures, utilizing literature soils subjected to varying net normal stresses, and across a wide range of matric suction up to the residual suction zone. It was established that a correlation existed between the scaling function and air-entry value for both small-strain shear modulus and shear strength of unsaturated soils. In addition, the behavior of the scaling function under potential hysteretic effects was demonstrated and recommendations were provided on how to apply the proposed model under such conditions. Finally, the modified equations including the correlation for the scaling function were used to predict additional literature soils.
{"title":"Development of a Scaling Function to Estimate Unsaturated Mechanical Soil Behavior from a Soil-Water Characteristic Curve","authors":"Lucas Acheampong, L. S. Bryson","doi":"10.1139/cgj-2023-0658","DOIUrl":"https://doi.org/10.1139/cgj-2023-0658","url":null,"abstract":"The small-strain shear modulus and shear strength are mechanical parameters crucial in the design of geotechnical structures and in the analyses of soil-structure interactions. This paper proposes a new approach for estimating these mechanical parameters. The proposed approach is predicated on the proportional inverse relationship of mechanical soil properties to the soil-water characteristic curve (SWCC). The proposed equations supporting the approach incorporate a scaling function, alongside the initial saturated mechanical property. The performance of the proposed equations was demonstrated across a variety of soil textures, utilizing literature soils subjected to varying net normal stresses, and across a wide range of matric suction up to the residual suction zone. It was established that a correlation existed between the scaling function and air-entry value for both small-strain shear modulus and shear strength of unsaturated soils. In addition, the behavior of the scaling function under potential hysteretic effects was demonstrated and recommendations were provided on how to apply the proposed model under such conditions. Finally, the modified equations including the correlation for the scaling function were used to predict additional literature soils.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"115 23","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141802257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Investigation on the thermo-mechanical volume change behavior of unsaturated bentonite is of great significance for successful design and construction of geological repositories. In this work, two types of thermo-mechanical volume change tests were carried out on unsaturated GMZ bentonite specimens. Results of temperature-suction controlled compression tests indicated that the virgin compression lines of unsaturated bentonite eventually converged toward that of saturated bentonite. With the concept of critical saturated state (CSS) curve, bilinear normal consolidation lines with consideration of temperature were proposed. Results of thermal loading tests indicated that the effects of over-consolidation ratio (OCR) on the thermal volume change behavior of unsaturated and saturated bentonite were similar, while, the suction effect on the thermal volume change behavior of unsaturated bentonite was different in unsaturated and critical saturated state. Based on the test results, a new concept of critical saturated state (CSS) surface was proposed in the stress space (s-p-T space) for compacted bentonite. In the new framework, the thermo-mechanical volume change behavior of unsaturated bentonite could be well described. The results obtained in this work could provide a new conception for developing the thermo-mechanical constitutive model for unsaturated bentonite.
{"title":"A new concept of CSS surface for describing the thermo-mechanical volume change of unsaturated bentonite","authors":"Yang Wang, Wei-min Ye, Qiong Wang, Yonggui Chen","doi":"10.1139/cgj-2024-0065","DOIUrl":"https://doi.org/10.1139/cgj-2024-0065","url":null,"abstract":"Investigation on the thermo-mechanical volume change behavior of unsaturated bentonite is of great significance for successful design and construction of geological repositories. In this work, two types of thermo-mechanical volume change tests were carried out on unsaturated GMZ bentonite specimens. Results of temperature-suction controlled compression tests indicated that the virgin compression lines of unsaturated bentonite eventually converged toward that of saturated bentonite. With the concept of critical saturated state (CSS) curve, bilinear normal consolidation lines with consideration of temperature were proposed. Results of thermal loading tests indicated that the effects of over-consolidation ratio (OCR) on the thermal volume change behavior of unsaturated and saturated bentonite were similar, while, the suction effect on the thermal volume change behavior of unsaturated bentonite was different in unsaturated and critical saturated state. Based on the test results, a new concept of critical saturated state (CSS) surface was proposed in the stress space (s-p-T space) for compacted bentonite. In the new framework, the thermo-mechanical volume change behavior of unsaturated bentonite could be well described. The results obtained in this work could provide a new conception for developing the thermo-mechanical constitutive model for unsaturated bentonite.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"45 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141803763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Development of the constitutive model for bentonite under coupled thermo-hydro-mechanical (THM) condition is of great significance for the construction and safety assessment of deep geological disposal repositories for high-level radioactive waste (HLW). In this work, a new temperature-suction-mean net stress (T-s-p) space with the conception of critical saturated state (CSS) surface was defined to represent the actual stress state of bentonite under coupled THM condition. Then, based on the CSS surface, a THM constitutive model was proposed for describing the volumetric behavior of compacted bentonite. Under the THM model framework, two bounding surfaces were proposed to describe the elastoplastic volume changes induced by mechanical response of skeleton and hydration of montmorillonite, respectively. The model responses upon some typical THM paths were simulated and discussed to reveal the performance of the proposed constitutive model for bentonite. Finally, the proposed model was validated by simulating by several volume change tests carried out on different bentonites. The results confirmed that the proposed model shows more advantages in describing the THM volumetric behavior.
{"title":"A CSS surface based THM bounding constitutive model for volumetric behavior of bentonite","authors":"Yang Wang, Wei-min Ye, Qiong Wang, Yong-gui Chen","doi":"10.1139/cgj-2024-0100","DOIUrl":"https://doi.org/10.1139/cgj-2024-0100","url":null,"abstract":"Development of the constitutive model for bentonite under coupled thermo-hydro-mechanical (THM) condition is of great significance for the construction and safety assessment of deep geological disposal repositories for high-level radioactive waste (HLW). In this work, a new temperature-suction-mean net stress (T-s-p) space with the conception of critical saturated state (CSS) surface was defined to represent the actual stress state of bentonite under coupled THM condition. Then, based on the CSS surface, a THM constitutive model was proposed for describing the volumetric behavior of compacted bentonite. Under the THM model framework, two bounding surfaces were proposed to describe the elastoplastic volume changes induced by mechanical response of skeleton and hydration of montmorillonite, respectively. The model responses upon some typical THM paths were simulated and discussed to reveal the performance of the proposed constitutive model for bentonite. Finally, the proposed model was validated by simulating by several volume change tests carried out on different bentonites. The results confirmed that the proposed model shows more advantages in describing the THM volumetric behavior.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"23 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141810299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A field measurement was conducted on an H-pile driven into a multilayer soil profile to analyze the axial stresses/forces generated on the pile during bridge construction activities. Vibrating wire strain gauges and piezometers were utilized, and dynamic testing was conducted for this purpose. Measurements revealed that the pile's preinstallation and temperature changes after installation in cooler ground caused shifts in strain gauge readings. Furthermore, driving an adjacent pile into the vicinity equivalent to four pile diameters, caused a notable increase in pore water pressure, resulting in decreased stresses on the pile. Concreting on top of the pile induced compressive stress during the first day, followed by a considerable decrease and development of tension on the pile over the next two days. Considering the residual force due to pile installation, force distribution, neutral plane location, and maximum axial force along the shaft were different and higher than in the case where this force was ignored. This paper presents a robust methodology to evaluate forces/stresses in a pile subject to installation through to final loading, including drag force effects based on instrumentation measurements. This novel approach provides a better understanding of drag force impacts on actual load capacity under final production loading.
对打入多层土壤剖面的 H 型桩进行了实地测量，以分析桥梁施工活动中对桩产生的轴向应力/力。为此使用了振动钢丝应变计和压强计，并进行了动态测试。测量结果表明，桩在安装前和安装到较冷地层后的温度变化会导致应变仪读数的变化。此外，将邻近的一根桩打入附近相当于四根桩直径的位置，会导致孔隙水压力明显增加，从而使桩上的应力减小。在桩顶浇筑混凝土会在第一天产生压缩应力，随后两天应力会大幅减小，并在桩上产生拉力。考虑到由于桩的安装而产生的残余力，沿轴的力分布、中性面位置和最大轴向力与忽略残余力的情况不同，且更大。本文介绍了一种稳健的方法，用于评估桩从安装到最终加载期间的力/应力，包括基于仪器测量的阻力效应。通过这种新颖的方法，可以更好地了解阻力对最终生产荷载下实际承载能力的影响。
{"title":"Interpretation Considerations for Field Study of Axial Stresses/Forces in Driven H-Piles Due to Construction Activities for Fill Placement","authors":"Sepehr Chalajour, James A. Blatz","doi":"10.1139/cgj-2024-0111","DOIUrl":"https://doi.org/10.1139/cgj-2024-0111","url":null,"abstract":"A field measurement was conducted on an H-pile driven into a multilayer soil profile to analyze the axial stresses/forces generated on the pile during bridge construction activities. Vibrating wire strain gauges and piezometers were utilized, and dynamic testing was conducted for this purpose. Measurements revealed that the pile's preinstallation and temperature changes after installation in cooler ground caused shifts in strain gauge readings. Furthermore, driving an adjacent pile into the vicinity equivalent to four pile diameters, caused a notable increase in pore water pressure, resulting in decreased stresses on the pile. Concreting on top of the pile induced compressive stress during the first day, followed by a considerable decrease and development of tension on the pile over the next two days. Considering the residual force due to pile installation, force distribution, neutral plane location, and maximum axial force along the shaft were different and higher than in the case where this force was ignored. This paper presents a robust methodology to evaluate forces/stresses in a pile subject to installation through to final loading, including drag force effects based on instrumentation measurements. This novel approach provides a better understanding of drag force impacts on actual load capacity under final production loading.","PeriodicalId":505159,"journal":{"name":"Canadian Geotechnical Journal","volume":"117 28","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141821254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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