Tian Jia, S. Stanier, P. Watson, Xiaowei Feng, S. Gourvenec
Tolerably mobile subsea foundations are designed to slide on the seabed to accommodate flowline thermal expansion and contraction, and are a potential alternative to conventional (fixed) foundations. During the periodic sliding events that occur during operation, soil berms form at the extremities of the foundation footprint. The size of the berm increases throughout the life-cycle of the foundation, leading to increasing peak sliding resistance. This may hinder mobility of foundation and overstress the pipeline connections that the foundation is designed to support. Equally, the berms may be relied on to reduce sliding and thus minimize settlement of the foundation, which can also overstress pipeline connections. This paper analyses the mechanism leading to berm accumulation and its mobilisation, also addressing periodic remoulding and reconsolidation of the sediment in the berm. A framework is proposed to predict the accumulation of soil berms and the resulting peak sliding resistance, and is validated by eight centrifuge model tests performed on a kaolin clay and a carbonate silt.
{"title":"Theoretical framework for predicting accumulation of soil berms and peak sliding resistance for tolerably mobile foundations","authors":"Tian Jia, S. Stanier, P. Watson, Xiaowei Feng, S. Gourvenec","doi":"10.1139/cgj-2023-0138","DOIUrl":"https://doi.org/10.1139/cgj-2023-0138","url":null,"abstract":"Tolerably mobile subsea foundations are designed to slide on the seabed to accommodate flowline thermal expansion and contraction, and are a potential alternative to conventional (fixed) foundations. During the periodic sliding events that occur during operation, soil berms form at the extremities of the foundation footprint. The size of the berm increases throughout the life-cycle of the foundation, leading to increasing peak sliding resistance. This may hinder mobility of foundation and overstress the pipeline connections that the foundation is designed to support. Equally, the berms may be relied on to reduce sliding and thus minimize settlement of the foundation, which can also overstress pipeline connections. This paper analyses the mechanism leading to berm accumulation and its mobilisation, also addressing periodic remoulding and reconsolidation of the sediment in the berm. A framework is proposed to predict the accumulation of soil berms and the resulting peak sliding resistance, and is validated by eight centrifuge model tests performed on a kaolin clay and a carbonate silt.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"138 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77407414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hao Zhang, Honglei Sun, S. Liu, Xueyu Geng, Y. Deng, Yuanqiang Cai
Treating the high water-content sludge with vacuum-assisted prefabricated horizontal drains (PHDs) placed inside, geotextile tubes have the advantage of multiple drainage paths, and geomembrane tubes have the superiority of high vacuum maintenance. Therefore, converting the geotextile tube into a geomembrane tube during slurry dewatering is an effective measure for greater dewatering efficiency and better dehydration effect. In this study, a profound plane-strain consolidation model considering two-dimensional seepage is developed for explaining the dewatering mechanism of sludge in the geo-tubes. Analytical solutions are given and validated by the experiment. The impact of major variables on tube efficiency is further discussed to reference the practice design. Parametric analyses reveal the critical time corresponding to the optimal efficiency of the geotextile tube, after which its consolidation efficiency decreases significantly. However, the consolidation efficiency of a geomembrane tube increases throughout the duration. Consequently, a switching point corresponding to the iso-efficiency state of the geotextile tube and geomembrane tube can be determined for the tube conversion.
{"title":"Combined vacuum-assisted geotextile and geomembrane tubes for sludge dewatering: A theoretical switching point","authors":"Hao Zhang, Honglei Sun, S. Liu, Xueyu Geng, Y. Deng, Yuanqiang Cai","doi":"10.1139/cgj-2022-0370","DOIUrl":"https://doi.org/10.1139/cgj-2022-0370","url":null,"abstract":"Treating the high water-content sludge with vacuum-assisted prefabricated horizontal drains (PHDs) placed inside, geotextile tubes have the advantage of multiple drainage paths, and geomembrane tubes have the superiority of high vacuum maintenance. Therefore, converting the geotextile tube into a geomembrane tube during slurry dewatering is an effective measure for greater dewatering efficiency and better dehydration effect. In this study, a profound plane-strain consolidation model considering two-dimensional seepage is developed for explaining the dewatering mechanism of sludge in the geo-tubes. Analytical solutions are given and validated by the experiment. The impact of major variables on tube efficiency is further discussed to reference the practice design. Parametric analyses reveal the critical time corresponding to the optimal efficiency of the geotextile tube, after which its consolidation efficiency decreases significantly. However, the consolidation efficiency of a geomembrane tube increases throughout the duration. Consequently, a switching point corresponding to the iso-efficiency state of the geotextile tube and geomembrane tube can be determined for the tube conversion.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"50 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85714163","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rockfalls can often pose a significant risk to the public if protective designs do not properly account for block movement downslope and onto infrastructure facilities. Assessing these hazards is challenging, especially as current empirical and computational methods for predicting trajectories of falling blocks generally do not include the contribution associated with rotational behavior. Research undertaken at the University of New Hampshire, USA, over the last decade has led to the development of Smart Rock (SR) sensors inserted in natural rocks to evaluate these events from the perspective of the falling rock. The latest SRs consist of 3D printed capsules 58.0 mm in length and 25.4 mm in diameter, equipped with a ±400 g and a ±16 g 3-axis accelerometer, a ±4000 dps high-rate gyroscope, and an altimeter. Approximately 80 field experiments conducted in New Hampshire and Vermont provided SR data on rockfall at ten different sites. The Smart Rock data allowed more in-depth evaluations of accelerations, rotation rates, and modes of motion with precise time intervals, which cannot be easily captured in video recording systems or other instrumentation techniques. Such measurements are essential to improve our understanding and modeling of rockfall events for more economical and safer design of protective systems.
如果保护设计没有适当考虑到石块下坡和基础设施的移动，落石往往会对公众构成重大风险。评估这些危险是具有挑战性的，特别是目前用于预测落块轨迹的经验和计算方法通常不包括与旋转行为相关的贡献。美国新罕布什尔大学(University of New Hampshire)在过去十年中进行的研究导致了智能岩石(SR)传感器的发展，该传感器插入天然岩石中，从落石的角度评估这些事件。最新的SRs由长58.0 mm、直径25.4 mm的3D打印胶囊组成，配备±400 g和±16 g的3轴加速度计、±4000 dps的高速陀螺仪和高度计。在新罕布什尔州和佛蒙特州进行的大约80次实地试验提供了10个不同地点的岩落SR数据。Smart Rock的数据可以更深入地评估加速度、旋转速率和运动模式，以及精确的时间间隔，这些都是视频记录系统或其他仪器技术无法轻易捕捉到的。这些测量对于提高我们对岩崩事件的理解和建模，从而设计更经济、更安全的防护系统至关重要。
{"title":"Rockfall motion using a Smart Rock sensor","authors":"Bruma Souza, J. Benoît","doi":"10.1139/cgj-2022-0599","DOIUrl":"https://doi.org/10.1139/cgj-2022-0599","url":null,"abstract":"Rockfalls can often pose a significant risk to the public if protective designs do not properly account for block movement downslope and onto infrastructure facilities. Assessing these hazards is challenging, especially as current empirical and computational methods for predicting trajectories of falling blocks generally do not include the contribution associated with rotational behavior. Research undertaken at the University of New Hampshire, USA, over the last decade has led to the development of Smart Rock (SR) sensors inserted in natural rocks to evaluate these events from the perspective of the falling rock. The latest SRs consist of 3D printed capsules 58.0 mm in length and 25.4 mm in diameter, equipped with a ±400 g and a ±16 g 3-axis accelerometer, a ±4000 dps high-rate gyroscope, and an altimeter. Approximately 80 field experiments conducted in New Hampshire and Vermont provided SR data on rockfall at ten different sites. The Smart Rock data allowed more in-depth evaluations of accelerations, rotation rates, and modes of motion with precise time intervals, which cannot be easily captured in video recording systems or other instrumentation techniques. Such measurements are essential to improve our understanding and modeling of rockfall events for more economical and safer design of protective systems.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"357 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80162445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bentonite slurry is frequently used to temporarily stabilize the excavation for slurry tunnel boring machines (TBMs) driving in permeable soils, such as sand and gravel. In this study, two types of bentonite slurries (BS1 and BS2) were subjected to a series of infiltration column tests and modified fluid-loss tests under various pressure levels. Monitoring of water discharge and pore pressures at different depths of the sand bed enabled the identification of two effective sealing patterns during infiltration: the formation of a filter cake and rheological blocking. BS1 exhibited a tendency to form a filter cake, which played a vital role in effectively transferring the applied pressure to the underlying soil skeleton. The application of higher pressure facilitated the rapid formation of a filter cake, resulting in a shorter time span for slurry invasion and minimizing fluid loss. On the other hand, rheological blocking was dominant when using BS2, and the maximum infiltration distance was found to linearly increase with the applied pressure. A comparison between the measurement and a simple prediction model derived from Darcy’s law revealed an overestimation of the infiltration distance during slurry invasion. Furthermore, based on the modified fluid-loss test, higher pressure was found to densify the filter cake and result in lower hydraulic conductivity.
{"title":"Pressure infiltration behavior and fluid loss of bentonite slurry: A comparative study of two bentonite slurries","authors":"Su Qin, Yangrui Cheng, He Huang, Wan-Huan Zhou","doi":"10.1139/cgj-2023-0103","DOIUrl":"https://doi.org/10.1139/cgj-2023-0103","url":null,"abstract":"Bentonite slurry is frequently used to temporarily stabilize the excavation for slurry tunnel boring machines (TBMs) driving in permeable soils, such as sand and gravel. In this study, two types of bentonite slurries (BS1 and BS2) were subjected to a series of infiltration column tests and modified fluid-loss tests under various pressure levels. Monitoring of water discharge and pore pressures at different depths of the sand bed enabled the identification of two effective sealing patterns during infiltration: the formation of a filter cake and rheological blocking. BS1 exhibited a tendency to form a filter cake, which played a vital role in effectively transferring the applied pressure to the underlying soil skeleton. The application of higher pressure facilitated the rapid formation of a filter cake, resulting in a shorter time span for slurry invasion and minimizing fluid loss. On the other hand, rheological blocking was dominant when using BS2, and the maximum infiltration distance was found to linearly increase with the applied pressure. A comparison between the measurement and a simple prediction model derived from Darcy’s law revealed an overestimation of the infiltration distance during slurry invasion. Furthermore, based on the modified fluid-loss test, higher pressure was found to densify the filter cake and result in lower hydraulic conductivity.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"222 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79937481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A framework for thaw consolidation of fine-grained soils is proposed. The development of the framework is based on the general definition of large-strain consolidation and on the general behaviour of soils upon thawing. The residual stress and the residual stress curve are used in the framework to define the initial thawed state. The concept of the residual stress is generalized to ice-rich soils by specifying that the residual stress is the effective stress within the soil elements upon thawing rather than the effective stress in the bulk soil. The framework is formulated in terms of σ'_v - e - k_v relationships. The volume change behaviour of ice-poor soils is described by a semi-logarithmic linear relationship. The slope of the relationship is given by the compression index of the thawed soil. For ice-rich soils, a bilinear relationship is adopted. First, drainage of the excess water occurs with no compression of the soil skeleton. Then, water is drained out of the soil upon compression of the soil skeleton in an ice-poor equivalent manner. The hydraulic conductivity relationship of thawed fine-grained soils is defined by a semi-logarithmic linear curve with a slope defined by the hydraulic conductivity change index of the thawed soil.
提出了细粒土解冻固结的框架。框架的发展是基于大应变固结的一般定义和土壤在融化时的一般行为。在框架中使用残余应力和残余应力曲线来定义初始解冻状态。将残余应力的概念推广到富冰土壤中，指出残余应力是融化时土体单元内的有效应力，而不是土体中的有效应力。该框架是用σ'_v - e - k_v关系表示的。贫冰土壤的体积变化行为用半对数线性关系来描述。关系的斜率由解冻土壤的压缩指数给出。对于富冰土壤，采用双线性关系。首先，在不压缩土壤骨架的情况下排水多余的水。然后，在压缩土壤骨架时，水以一种贫冰等效的方式从土壤中排出。细粒土融化后的导电性关系由一条半对数线性曲线定义，其斜率由融化后土壤的导电性变化指数定义。
{"title":"Framework for Thaw Consolidation of Fine-Grained Soils","authors":"S. Dumais, J. Konrad","doi":"10.1139/cgj-2022-0502","DOIUrl":"https://doi.org/10.1139/cgj-2022-0502","url":null,"abstract":"A framework for thaw consolidation of fine-grained soils is proposed. The development of the framework is based on the general definition of large-strain consolidation and on the general behaviour of soils upon thawing. The residual stress and the residual stress curve are used in the framework to define the initial thawed state. The concept of the residual stress is generalized to ice-rich soils by specifying that the residual stress is the effective stress within the soil elements upon thawing rather than the effective stress in the bulk soil. The framework is formulated in terms of σ'_v - e - k_v relationships. The volume change behaviour of ice-poor soils is described by a semi-logarithmic linear relationship. The slope of the relationship is given by the compression index of the thawed soil. For ice-rich soils, a bilinear relationship is adopted. First, drainage of the excess water occurs with no compression of the soil skeleton. Then, water is drained out of the soil upon compression of the soil skeleton in an ice-poor equivalent manner. The hydraulic conductivity relationship of thawed fine-grained soils is defined by a semi-logarithmic linear curve with a slope defined by the hydraulic conductivity change index of the thawed soil.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"33 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75455780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The traditional method for analysis of laterally loaded piles with noncircular cross sections such as rectangular, H-shaped, and X-shaped piles involves the simplification of converting the noncircular pile to equivalent circular pile. A robust and rigorous semi-analytical method is developed for calculating the response for laterally loaded piles with arbitrary noncircular cross sections in multi-layered elastic soil without using any simplification regarding the shape of the pile cross section. The governing differential equations for the pile-soil system are obtained using the principle of virtual work. The soil displacements around the pile are described as products of separable functions that are compatible with horizontal pile movement. As a result, the three-dimensional (3D) boundary value problem (BVP) is described by a fourth-order linear ordinary differential equation (ODE) governing horizontal pile displacement and second-order partial differential equations (PDEs) governing soil displacements. New solution techniques for the ODE and PDEs are proposed, and the accuracy of the present method is verified by comparing the predicted pile and soil responses with the corresponding results of equivalent 3D finite element method (FEM). The effects of pile cross-section shape and lateral loading direction on the pile and soil responses are highlighted through a series of parametric analyses.
{"title":"A Semi-Analytical Solution for Laterally Loaded Noncircular Piles in Elastic Soil","authors":"Hang Zhou, Zengliang Wang, D. Basu, Han Liu","doi":"10.1139/cgj-2022-0354","DOIUrl":"https://doi.org/10.1139/cgj-2022-0354","url":null,"abstract":"The traditional method for analysis of laterally loaded piles with noncircular cross sections such as rectangular, H-shaped, and X-shaped piles involves the simplification of converting the noncircular pile to equivalent circular pile. A robust and rigorous semi-analytical method is developed for calculating the response for laterally loaded piles with arbitrary noncircular cross sections in multi-layered elastic soil without using any simplification regarding the shape of the pile cross section. The governing differential equations for the pile-soil system are obtained using the principle of virtual work. The soil displacements around the pile are described as products of separable functions that are compatible with horizontal pile movement. As a result, the three-dimensional (3D) boundary value problem (BVP) is described by a fourth-order linear ordinary differential equation (ODE) governing horizontal pile displacement and second-order partial differential equations (PDEs) governing soil displacements. New solution techniques for the ODE and PDEs are proposed, and the accuracy of the present method is verified by comparing the predicted pile and soil responses with the corresponding results of equivalent 3D finite element method (FEM). The effects of pile cross-section shape and lateral loading direction on the pile and soil responses are highlighted through a series of parametric analyses.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"1967 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91389111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microbial induced calcium carbonate precipitation (MICP) offers a sustainable technique to improve geologic properties of soils in engineering structures. The applications encompass improved soil strength, scour mitigation, fracture sealing, and in situ contaminant immobilization. Previous studies have presented fundamental processes and implementation in lab- and field-scale. Most of these studies were examined in saturated conditions despite many MICP applications including those in coastal and riverside areas which will likely take place under unsaturated conditions. The study herein investigated the effect of soil water retention curve (SWRC) parameters and attachment coefficient (Kat) on CaCO3 precipitation in sand. Using numerical analyses, a continuum model was developed in which unsaturated flow and transport were coupled with biological and chemical reactions in variably saturated conditions. Predictive modeling results compare mass percentage of calcium carbonate resulting from MICP at degrees of soil water saturations of 20%, 40%, 80%, and 100% in sandy soil media. The results indicate the bacteria attachment coefficient increases by a factor of 3 as the degree of saturation is decreased from 100% to 20%, as the higher suctions at lower saturation levels improve bacteria fixation. The drying branch of SWRC versus wetting front yields higher CaCO3 for identical MICP treatment. Numerical results show the trend in hydraulic conductivity with increasing cementation level.
{"title":"Development of a Reactive Transport Model for Microbial Induced Calcium Carbonate Precipitation in Unsaturated Conditions","authors":"Z. Faeli, B. Montoya, M. Gabr","doi":"10.1139/cgj-2022-0677","DOIUrl":"https://doi.org/10.1139/cgj-2022-0677","url":null,"abstract":"Microbial induced calcium carbonate precipitation (MICP) offers a sustainable technique to improve geologic properties of soils in engineering structures. The applications encompass improved soil strength, scour mitigation, fracture sealing, and in situ contaminant immobilization. Previous studies have presented fundamental processes and implementation in lab- and field-scale. Most of these studies were examined in saturated conditions despite many MICP applications including those in coastal and riverside areas which will likely take place under unsaturated conditions. The study herein investigated the effect of soil water retention curve (SWRC) parameters and attachment coefficient (Kat) on CaCO3 precipitation in sand. Using numerical analyses, a continuum model was developed in which unsaturated flow and transport were coupled with biological and chemical reactions in variably saturated conditions. Predictive modeling results compare mass percentage of calcium carbonate resulting from MICP at degrees of soil water saturations of 20%, 40%, 80%, and 100% in sandy soil media. The results indicate the bacteria attachment coefficient increases by a factor of 3 as the degree of saturation is decreased from 100% to 20%, as the higher suctions at lower saturation levels improve bacteria fixation. The drying branch of SWRC versus wetting front yields higher CaCO3 for identical MICP treatment. Numerical results show the trend in hydraulic conductivity with increasing cementation level.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"88 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82343475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xu Li, Lei-jie Wu, Y. J. Wang, Huan Liu, Zu-yu Chen, Liu-jie Jing, Yu Wang
In Tunnel boring Machine (TBM) construction, the presence of collapsible rock mass (CRM) can lead to accidents such as collapse and jamming. This study presents a novel CRM early warning strategy based on real-time TBM rock fragmentation data to improve safety and efficiency in CRM conditions. The strategy includes a qualitative classification model and a quantitative probability model for CRM identification. The results indicate that the distribution dissimilarity index β effectively reflect the significance of variables across CRM and non-CRM datasets. Various parameters, including TPI, FPI, WR, and AF, show discriminatory ability between CRM and non-CRM samples. In particular, the CRM-weighted index, which combines the strengths of the individual indices, achieves a distributional dissimilarity index of 1.05, significantly higher than any of the individual indices. The qualitative classification model proves effective in identifying samples from collapse areas, demonstrating ability to identify samples located in adverse geological condition. The quantitative model shows that the probability of CRM is generally higher in adverse geological area samples, particularly in zones where collapse has occurred, with a CRM probability is approaching 1. The proposed strategy provides accurate early warnings to prevent collapse accidents and represents a practical approach to improving the safety and efficiency.
{"title":"A data driven real-time perception method of rock condition in TBM construction","authors":"Xu Li, Lei-jie Wu, Y. J. Wang, Huan Liu, Zu-yu Chen, Liu-jie Jing, Yu Wang","doi":"10.1139/cgj-2023-0168","DOIUrl":"https://doi.org/10.1139/cgj-2023-0168","url":null,"abstract":"In Tunnel boring Machine (TBM) construction, the presence of collapsible rock mass (CRM) can lead to accidents such as collapse and jamming. This study presents a novel CRM early warning strategy based on real-time TBM rock fragmentation data to improve safety and efficiency in CRM conditions. The strategy includes a qualitative classification model and a quantitative probability model for CRM identification. The results indicate that the distribution dissimilarity index β effectively reflect the significance of variables across CRM and non-CRM datasets. Various parameters, including TPI, FPI, WR, and AF, show discriminatory ability between CRM and non-CRM samples. In particular, the CRM-weighted index, which combines the strengths of the individual indices, achieves a distributional dissimilarity index of 1.05, significantly higher than any of the individual indices. The qualitative classification model proves effective in identifying samples from collapse areas, demonstrating ability to identify samples located in adverse geological condition. The quantitative model shows that the probability of CRM is generally higher in adverse geological area samples, particularly in zones where collapse has occurred, with a CRM probability is approaching 1. The proposed strategy provides accurate early warnings to prevent collapse accidents and represents a practical approach to improving the safety and efficiency.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"56 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87036452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Cone Penetration Test (CPT) is a widely used site investigation tool due to its accuracy and wealth of data at a relatively low cost. Virtually all CPT interpretations explicitly or implicitly depend on how the in-situ state parameter is correlated to the tip resistance. Accurate interpretation of the state parameter from CPT is the basis for evaluating strength and liquefaction susceptibility of granular soils. The handful of interpretation methods used in the industry range between empirical and semi-empirical. As is the case for all empirical methods, extrapolating these methods outside of the original database, especially to significantly different soils such as silt-rich tailings, brings about significant risk. This paper presents a new method of interpreting the state parameter from a fully validated model of the cone penetration in sand. The method has no empirical elements and produces soil-specific correlations between the tip resistance and the state parameter. It can be easily implemented in a spreadsheet and does not require complicated analyses. The method differentiates among soils through calibration of a critical state based constitutive model, Norsand, through triaxial compression tests. The potential errors induced by not measuring soil properties are quantified.
{"title":"Material-specific interpretation of the state parameter from drained cone penetration test","authors":"M. Mozaffari, M. Ghafghazi","doi":"10.1139/cgj-2022-0490","DOIUrl":"https://doi.org/10.1139/cgj-2022-0490","url":null,"abstract":"The Cone Penetration Test (CPT) is a widely used site investigation tool due to its accuracy and wealth of data at a relatively low cost. Virtually all CPT interpretations explicitly or implicitly depend on how the in-situ state parameter is correlated to the tip resistance. Accurate interpretation of the state parameter from CPT is the basis for evaluating strength and liquefaction susceptibility of granular soils. The handful of interpretation methods used in the industry range between empirical and semi-empirical. As is the case for all empirical methods, extrapolating these methods outside of the original database, especially to significantly different soils such as silt-rich tailings, brings about significant risk. This paper presents a new method of interpreting the state parameter from a fully validated model of the cone penetration in sand. The method has no empirical elements and produces soil-specific correlations between the tip resistance and the state parameter. It can be easily implemented in a spreadsheet and does not require complicated analyses. The method differentiates among soils through calibration of a critical state based constitutive model, Norsand, through triaxial compression tests. The potential errors induced by not measuring soil properties are quantified.","PeriodicalId":9382,"journal":{"name":"Canadian Geotechnical Journal","volume":"10 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86507288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：