Stephen Buttling, Bengt H. Fellenius, Naruedol Pinijpol
This is the first of two papers on a wide pile group. In this part, the geology and a geotechnical model of the site are presented, along with the design of a single pile, analysis of a static loading test, and some dynamic tests. The response of the piled foundations comprising 399 bored piles supporting three 70-storey towers on a common mat was monitored over nine years. The records consist of results of a static loading test to 3.5 times the sustained load, dynamic tests of four piles, and monitoring the development of load in 15 piles and settlement of 40 points during construction and nine years following. At end of construction, the perimeter piles received more load from the towers than did the interior piles and the mat settled on average 90 mm. At the end of the monitoring period, due to the general subsidence, the average settlement of the mat had increased by 50 mm. Most of the settlement is considered to originate from the compression of the soil layers below the pile toe level. A subsequent paper will present the analysis and design of the wide pile group, and the numerical analysis of the static loading test on a single pile and of the wide pile group.
{"title":"A case history of monitoring a wide pile group Part I: geology, single pile analysis and testing, and monitoring data","authors":"Stephen Buttling, Bengt H. Fellenius, Naruedol Pinijpol","doi":"10.1680/jgeen.23.00001","DOIUrl":"https://doi.org/10.1680/jgeen.23.00001","url":null,"abstract":"This is the first of two papers on a wide pile group. In this part, the geology and a geotechnical model of the site are presented, along with the design of a single pile, analysis of a static loading test, and some dynamic tests. The response of the piled foundations comprising 399 bored piles supporting three 70-storey towers on a common mat was monitored over nine years. The records consist of results of a static loading test to 3.5 times the sustained load, dynamic tests of four piles, and monitoring the development of load in 15 piles and settlement of 40 points during construction and nine years following. At end of construction, the perimeter piles received more load from the towers than did the interior piles and the mat settled on average 90 mm. At the end of the monitoring period, due to the general subsidence, the average settlement of the mat had increased by 50 mm. Most of the settlement is considered to originate from the compression of the soil layers below the pile toe level. A subsequent paper will present the analysis and design of the wide pile group, and the numerical analysis of the static loading test on a single pile and of the wide pile group.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140836174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhenya Li, Xianbin He, Chiheng Zhao, Yuqian Xi, Cun Zhang
The tapered pile is usually divided into finite segments along the vertical direction due to its variable cross-section when investigating its torsional dynamic characteristics. However, an annular projection would be formed at the contact surface of the adjacent pile segments due to the difference in radius, through which the surrounding soil will apply the circumferential support on the pile segment. In this study, the Voigt model is adopted to model the circumferential support of the surrounding soil acting on the annular projection. On this basis, an amended impedance function transfer method is established combining with the circumferential stress equilibrium equations and circumferential displacement continuity conditions at the contact surface of the adjacent pile segments. The shear complex stiffness transfer method is employed to consider the construction disturbance during pile installation. Then, an improved analytical solution for the torsional vibration of the tapered pile considering the circumferential support of the surrounding soil is established by solving the equations for the soil and pile. Based on the solution, the torsional vibration of the tapered pile is investigated and the influence of the circumferential support of the surrounding soil is revealed under different pile parameters and construction disturbance conditions.
{"title":"Torsional vibration of a tapered pile considering circumferential support of surrounding soil","authors":"Zhenya Li, Xianbin He, Chiheng Zhao, Yuqian Xi, Cun Zhang","doi":"10.1680/jgeen.23.00102","DOIUrl":"https://doi.org/10.1680/jgeen.23.00102","url":null,"abstract":"The tapered pile is usually divided into finite segments along the vertical direction due to its variable cross-section when investigating its torsional dynamic characteristics. However, an annular projection would be formed at the contact surface of the adjacent pile segments due to the difference in radius, through which the surrounding soil will apply the circumferential support on the pile segment. In this study, the Voigt model is adopted to model the circumferential support of the surrounding soil acting on the annular projection. On this basis, an amended impedance function transfer method is established combining with the circumferential stress equilibrium equations and circumferential displacement continuity conditions at the contact surface of the adjacent pile segments. The shear complex stiffness transfer method is employed to consider the construction disturbance during pile installation. Then, an improved analytical solution for the torsional vibration of the tapered pile considering the circumferential support of the surrounding soil is established by solving the equations for the soil and pile. Based on the solution, the torsional vibration of the tapered pile is investigated and the influence of the circumferential support of the surrounding soil is revealed under different pile parameters and construction disturbance conditions.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140581625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hisham T. Eid, Mohammed Z. E. B. Elshafie, Barry O'Sullivan, Mohamed E. Khalil, Alhassan Mahmoud, Reiner Stollberg
Through analysing a significant number of case histories, ranges of applications of dewatering techniques for randomly fractured rock are proposed in terms of the rock mass permeability and the required drawdown. The cases analysed, which cover a wide range of construction activities and associated dewatering depths, provide one of the most comprehensive studies of dewatering techniques on randomly fractured rock to date. Comparison of the ranges suggested for dewatering in fractured rocks with those developed for excavations in soils is presented. To fit the construction dewatering systems in rock, a modification is proposed for the drawdown diagram that is widely used in practice for soils, and for the limited available general recommendations presented for chalk. Consequently, recommendations are made to improve the procedure of designing and executing these systems. In addition, a dewatering technique is proposed, which allows for construction to proceed in a wet condition, taking into account rock shear strength and the excavation geometry.
{"title":"Applicability of construction dewatering techniques for randomly fractured rock","authors":"Hisham T. Eid, Mohammed Z. E. B. Elshafie, Barry O'Sullivan, Mohamed E. Khalil, Alhassan Mahmoud, Reiner Stollberg","doi":"10.1680/jgeen.23.00005","DOIUrl":"https://doi.org/10.1680/jgeen.23.00005","url":null,"abstract":"Through analysing a significant number of case histories, ranges of applications of dewatering techniques for randomly fractured rock are proposed in terms of the rock mass permeability and the required drawdown. The cases analysed, which cover a wide range of construction activities and associated dewatering depths, provide one of the most comprehensive studies of dewatering techniques on randomly fractured rock to date. Comparison of the ranges suggested for dewatering in fractured rocks with those developed for excavations in soils is presented. To fit the construction dewatering systems in rock, a modification is proposed for the drawdown diagram that is widely used in practice for soils, and for the limited available general recommendations presented for chalk. Consequently, recommendations are made to improve the procedure of designing and executing these systems. In addition, a dewatering technique is proposed, which allows for construction to proceed in a wet condition, taking into account rock shear strength and the excavation geometry.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140316263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qiang Shen, Yujie Wang, Ruilang Cao, Yufei Zhao, Yaoru Liu
Drilling operations are extensively used for underground excavation, and their efficiency has a direct impact on project duration and expenses. Adjusting the operational parameters during the drilling process is important for improving drilling efficiency. In this study, the sensitivity of drilling efficiency to operational parameters was investigated. Full-scale drilling tests for a dolomite block were conducted using a hydraulic drifter, and the Measurement While Drilling system was used to record the drilling data. Orthogonal schemes were designed to arrange the tests, and the penetration rate, specific energy, and rate-energy ratio were regarded as evaluation indices to assess the drilling efficiency. The sensitivity of the evaluation indices to operational parameters was analysed using both range analysis and variance analysis. Results show that the optimal combination of parameters within the test range was determined to be the propelling pressure of 8.5 MPa, percussive pressure of 17.5 MPa, and rotary speed of 250 rev/min to obtain the maximum drilling efficiency. The sensitivity sequence of the rate-energy ratio was propelling pressure, percussive pressure, and rotary speed, with weights of 54.0, 38.7, and 7.3%, respectively. These findings can provide a valuable reference for adjusting the operational parameters of hydraulic drifters to optimise drilling efficiency.
{"title":"Sensitivity investigation of drilling efficiency to operational parameters of a drifter","authors":"Qiang Shen, Yujie Wang, Ruilang Cao, Yufei Zhao, Yaoru Liu","doi":"10.1680/jgeen.23.00190","DOIUrl":"https://doi.org/10.1680/jgeen.23.00190","url":null,"abstract":"Drilling operations are extensively used for underground excavation, and their efficiency has a direct impact on project duration and expenses. Adjusting the operational parameters during the drilling process is important for improving drilling efficiency. In this study, the sensitivity of drilling efficiency to operational parameters was investigated. Full-scale drilling tests for a dolomite block were conducted using a hydraulic drifter, and the Measurement While Drilling system was used to record the drilling data. Orthogonal schemes were designed to arrange the tests, and the penetration rate, specific energy, and rate-energy ratio were regarded as evaluation indices to assess the drilling efficiency. The sensitivity of the evaluation indices to operational parameters was analysed using both range analysis and variance analysis. Results show that the optimal combination of parameters within the test range was determined to be the propelling pressure of 8.5 MPa, percussive pressure of 17.5 MPa, and rotary speed of 250 rev/min to obtain the maximum drilling efficiency. The sensitivity sequence of the rate-energy ratio was propelling pressure, percussive pressure, and rotary speed, with weights of 54.0, 38.7, and 7.3%, respectively. These findings can provide a valuable reference for adjusting the operational parameters of hydraulic drifters to optimise drilling efficiency.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140200002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In recent years, there has been a focus on improving geotechnical systems by implementing and constructing new deep foundation such as helical and expanded piles. This study examined the effects of parameters such as embedment depth, pile geometry, and axial loading direction on the load-displacement behaviour of these piles. To conduct the research, a database was compiled consisting of 80 axial loading test records for different piles. The embedment depth of the piles ranged from 2.4 to 36.8 m, and the diameter of helices or expanded parts ranged from 254 to 1500 mm. The ultimate load of the piles was determined using the 2.5% and 5% displacement ratio criteria and the Brinch-Hansen 80% method. Additionally, hyperbolic functions were fitted to the load-displacement curves, allowing for consistent estimation of the limit load and the initial tangent modulus. Analysis of the results from the database revealed that the dominant factors influencing the ultimate load, limit load, maximum measured load, initial stiffness, and load-displacement behaviour were the ratio of helices or expanded part diameter to shaft diameter, shaft and toe surface area, and load direction. Correlations derived from the database were validated using measurements from eight full-scale helical and expanded piles.
{"title":"Hyperbolic load-displacement analysis of helical and expanded piles: database approach","authors":"A. Rahimi, A. Eslami, J. S. McCartney","doi":"10.1680/jgeen.23.00196","DOIUrl":"https://doi.org/10.1680/jgeen.23.00196","url":null,"abstract":"In recent years, there has been a focus on improving geotechnical systems by implementing and constructing new deep foundation such as helical and expanded piles. This study examined the effects of parameters such as embedment depth, pile geometry, and axial loading direction on the load-displacement behaviour of these piles. To conduct the research, a database was compiled consisting of 80 axial loading test records for different piles. The embedment depth of the piles ranged from 2.4 to 36.8 m, and the diameter of helices or expanded parts ranged from 254 to 1500 mm. The ultimate load of the piles was determined using the 2.5% and 5% displacement ratio criteria and the Brinch-Hansen 80% method. Additionally, hyperbolic functions were fitted to the load-displacement curves, allowing for consistent estimation of the limit load and the initial tangent modulus. Analysis of the results from the database revealed that the dominant factors influencing the ultimate load, limit load, maximum measured load, initial stiffness, and load-displacement behaviour were the ratio of helices or expanded part diameter to shaft diameter, shaft and toe surface area, and load direction. Correlations derived from the database were validated using measurements from eight full-scale helical and expanded piles.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140200355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alessio Höttges, Carlo Rabaiotti, Raphael Züger, Dominik Hauswirth
Self-drilling micropiles (SDM) are gaining popularity as bearing foundation elements, as this construction technique allows for considerable time and cost savings. However, the irregular geometry and variability in the bearing capacity present uncertainty and a significant risk that has limited SDM deployment. To date, no reliable technology has been used to measure the SDM geometry. This paper proposes a methodology that uses distributed fiber optics (DFO), heat conduction modeling, and inverse analysis to measure the pile geometry and could also be extended to assess its bearing capacity. The temperature distribution during cement hydration was measured using two DFO investigative technologies and was compared to traditional temperature measurements using point sensors. An inverse analysis of SDM geometry was subsequently carried out based on the DFO measurement of temperature a finite element (FE) heat conduction model and a calibration pile. Finally, the calculated pile geometry was compared to the geometry of excavated pile in the uppermost part. The methodology presented here is not only intended as a tool for designing SDMs but can also be deployed as a structural health monitoring system to detect and monitor crack formation.
{"title":"A novel methodology for geometry assessment of self-drilling micropiles using distributed fiber optic sensors","authors":"Alessio Höttges, Carlo Rabaiotti, Raphael Züger, Dominik Hauswirth","doi":"10.1680/jgeen.23.00113","DOIUrl":"https://doi.org/10.1680/jgeen.23.00113","url":null,"abstract":"Self-drilling micropiles (SDM) are gaining popularity as bearing foundation elements, as this construction technique allows for considerable time and cost savings. However, the irregular geometry and variability in the bearing capacity present uncertainty and a significant risk that has limited SDM deployment. To date, no reliable technology has been used to measure the SDM geometry. This paper proposes a methodology that uses distributed fiber optics (DFO), heat conduction modeling, and inverse analysis to measure the pile geometry and could also be extended to assess its bearing capacity. The temperature distribution during cement hydration was measured using two DFO investigative technologies and was compared to traditional temperature measurements using point sensors. An inverse analysis of SDM geometry was subsequently carried out based on the DFO measurement of temperature a finite element (FE) heat conduction model and a calibration pile. Finally, the calculated pile geometry was compared to the geometry of excavated pile in the uppermost part. The methodology presented here is not only intended as a tool for designing SDMs but can also be deployed as a structural health monitoring system to detect and monitor crack formation.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140205588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yingqi Bai, Junhua Xiao, Lihua Xue, Zhiyong Liu, Binglong Wang
Viable remediation of the large lateral deformation of high-speed railway (HSR) subgrades, especially in soft soil areas, is still absent. An integrated rectification scheme of high-pressure jet-grouting (HPJG) combined with stress-release techniques was conducted to rectify the large lateral deformation of an operational HSR subgrade in the soft soil area of China, but without the refined design and mechanical analysis before rectification due to the emergency. The objective of the study is to post-evaluate the rectification effects utilizing field monitoring data and numerical calculations. The monitoring data showed that the maximum lateral deviation of the subgrade was 69.1 mm, which almost met the expected correction requirements. However, the influence of the excess pore water pressure (EPWP) dissipation on the correction deviation was not considered in the scheme. Therefore, a numerical model was established to further investigate this effect and corresponding mitigation methods. The calculated results revealed that EPWP in the foundation dissipated mostly within six months after rectification, and the deformation loss accounted for 30.7% of the total deviation. Prolonging the interval of two-row pile construction can be a plausible approach to mitigate the deviation loss. The findings provide a feasible method for correcting large lateral deformation of HSR subgrades.
{"title":"Correction effect of jet-grouting on the high-speed railway subgrade lateral deformation on soft soil","authors":"Yingqi Bai, Junhua Xiao, Lihua Xue, Zhiyong Liu, Binglong Wang","doi":"10.1680/jgeen.23.00169","DOIUrl":"https://doi.org/10.1680/jgeen.23.00169","url":null,"abstract":"Viable remediation of the large lateral deformation of high-speed railway (HSR) subgrades, especially in soft soil areas, is still absent. An integrated rectification scheme of high-pressure jet-grouting (HPJG) combined with stress-release techniques was conducted to rectify the large lateral deformation of an operational HSR subgrade in the soft soil area of China, but without the refined design and mechanical analysis before rectification due to the emergency. The objective of the study is to post-evaluate the rectification effects utilizing field monitoring data and numerical calculations. The monitoring data showed that the maximum lateral deviation of the subgrade was 69.1 mm, which almost met the expected correction requirements. However, the influence of the excess pore water pressure (EPWP) dissipation on the correction deviation was not considered in the scheme. Therefore, a numerical model was established to further investigate this effect and corresponding mitigation methods. The calculated results revealed that EPWP in the foundation dissipated mostly within six months after rectification, and the deformation loss accounted for 30.7% of the total deviation. Prolonging the interval of two-row pile construction can be a plausible approach to mitigate the deviation loss. The findings provide a feasible method for correcting large lateral deformation of HSR subgrades.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140200004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study aims to evaluate the tensile performance of additively manufactured polyethylene terephthalate glycol (PETG) geogrids 3d printed using the material extrusion technique. The ‘Creality Ender-3 V-2‘ 3D printer was employed for this purpose. Subsequently, specimens were subjected to loading at a rate of 1 mm/min until failure occurred. The geometrical parameters investigated in this study included: (1) shape of the aperture (square, triangular, hexagonal), (2) aperture size, (3) rib thickness, and (4) type of junction. The results revealed that the failure of specimens was primarily brittle and independent of any specific geometrical configuration or modifications. The initiation of failure consistently originated from the junctions. Among specimens with typical junctions, the triaxial geogrids exhibited the highest tensile capacity, while among geogrids with modified junctions, the square geogrids performed the best. Additionally, the load capacity of geogrids was primarily governed by linear behaviour in terms of rib width, regardless of aperture size or shape whereas nonlinear regression model characterized the load-displacement curves. Finally, it is important to account for geometrical nonlinearity in specimens with hexagonal apertures.
{"title":"Preliminary study on tensile performance of 3D-printed geogrids- effects of various geometrical configurations","authors":"Milad Shirdel, Masood Farzam","doi":"10.1680/jgeen.23.00068","DOIUrl":"https://doi.org/10.1680/jgeen.23.00068","url":null,"abstract":"This study aims to evaluate the tensile performance of additively manufactured polyethylene terephthalate glycol (PETG) geogrids 3d printed using the material extrusion technique. The <i>‘Creality Ender-3 V-2</i>‘ 3D printer was employed for this purpose. Subsequently, specimens were subjected to loading at a rate of 1 mm/min until failure occurred. The geometrical parameters investigated in this study included: (1) shape of the aperture (square, triangular, hexagonal), (2) aperture size, (3) rib thickness, and (4) type of junction. The results revealed that the failure of specimens was primarily brittle and independent of any specific geometrical configuration or modifications. The initiation of failure consistently originated from the junctions. Among specimens with typical junctions, the triaxial geogrids exhibited the highest tensile capacity, while among geogrids with modified junctions, the square geogrids performed the best. Additionally, the load capacity of geogrids was primarily governed by linear behaviour in terms of rib width, regardless of aperture size or shape whereas nonlinear regression model characterized the load-displacement curves. Finally, it is important to account for geometrical nonlinearity in specimens with hexagonal apertures.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140200003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper seeks to promotes use of shear wave velocity (Vs) measurements in UK clays as a complement to more standard ground investigation techniques. Vs measurements seem repeatable and independent of the method of measurement used in isotropic soil conditions, e.g. soft clays. However in glacial tills, and especially in the overconsolidated clays of south-east UK, Vs measurements will differ depending on the direction of propagation and polarisation of the shear waves due to natural stress anisotropy and the fissured nature of the materials. Correlations between Vs and other in situ data and with a variety of soil properties can be very powerful and some have been proposed here for UK clays. However these correlations should ideally be local and only applied to other soils and areas with great caution. Other uses of the techniques, beyond those of classical dynamic analyses, have been described together with some future challenges. Uncertainties in the methods have been well researched and several methods have been proposed to deal with these uncertainties. Nonetheless advice from a geophysical colleague will enhance the geotechnical engineers’ use of Vs data.
本文旨在推广在英国粘土中使用剪切波速度（Vs）测量方法，作为更标准的地层勘察技术的补充。在各向同性的土壤条件下，例如在软粘土中，剪切波速度测量似乎具有可重复性，并且与所使用的测量方法无关。然而，在冰川淤积土中，尤其是在英国东南部的过固结粘土中，由于天然应力各向异性和材料的裂隙性质，Vs 测量值会因剪切波的传播方向和极化而不同。Vs 与其他现场数据以及各种土壤特性之间的相关性可能非常强大，在此针对英国粘土提出了一些相关性建议。不过，这些相关性最好是局部的，只有在非常谨慎的情况下才能应用到其他土壤和地区。除经典动态分析外，还介绍了这些技术的其他用途以及未来面临的一些挑战。对方法中的不确定性进行了深入研究，并提出了几种处理这些不确定性的方法。不过，地球物理同行的建议将有助于岩土工程师更好地使用 Vs 数据。
{"title":"Practical use of shear wave velocity measurements in UK clays (BGA Touring Lecture 2023)","authors":"Michael Long","doi":"10.1680/jgeen.23.00158","DOIUrl":"https://doi.org/10.1680/jgeen.23.00158","url":null,"abstract":"This paper seeks to promotes use of shear wave velocity (V<sub>s</sub>) measurements in UK clays as a complement to more standard ground investigation techniques. V<sub>s</sub> measurements seem repeatable and independent of the method of measurement used in isotropic soil conditions, e.g. soft clays. However in glacial tills, and especially in the overconsolidated clays of south-east UK, V<sub>s</sub> measurements will differ depending on the direction of propagation and polarisation of the shear waves due to natural stress anisotropy and the fissured nature of the materials. Correlations between V<sub>s</sub> and other in situ data and with a variety of soil properties can be very powerful and some have been proposed here for UK clays. However these correlations should ideally be local and only applied to other soils and areas with great caution. Other uses of the techniques, beyond those of classical dynamic analyses, have been described together with some future challenges. Uncertainties in the methods have been well researched and several methods have been proposed to deal with these uncertainties. Nonetheless advice from a geophysical colleague will enhance the geotechnical engineers’ use of V<sub>s</sub> data.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138688185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qi Liu, Xianfeng Liu, Jianguo Li, Shengyang Yuan, Peng He, A. Giacomini, O. Buzzi
This study investigates the dynamic behavior between a rockfall and a new anchor cable ribbed rockfall retaining walls on a rock shed, which is designed to meet project requirements due to the tremendous space occupation of the protection structure, via numerical simulations by the coupling between PFC3D (discrete element method, DEM) and FLAC3D (finite element method, FEM). In the model, the slope model was imported after the point cloud of the slope was processed. The novel structure is modeled by the finite element method (FEM) through the zone element, while the rockfall and the buffer layer are modeled by the discrete element method (DEM) through the ball element. The dynamic movement of rockfall was traced, and the impact position and velocity were obtained on the structure. The numerical results show that three stages of the rockfall movement were modeled, namely, movement, impact, and stagnation. The rockfall falls on the slope, impacting the buffer layer on the top of the rock shed, before rebounding to the anchored rockfall retaining walls (with a height lower than 2 m). Then, the stress and deflection can be unified and related to the impact velocity of rockfall to examine the stability of the structure. In addition, the rockfall radius is the dominant parameter in the three parameters (rockfall shape, rockfall radius, and impact velocity). While the study focuses on a specific case study, the results provide valuable guidelines for future applications of the proposed combined structure for railway transportation protection.
采用PFC3D (discrete element method, DEM)和FLAC3D (finite element method, FEM)耦合的数值模拟方法，研究了因保护结构占用空间大而满足工程要求而设计的岩棚新型锚索肋式落石挡土墙与岩崩之间的动力行为。在模型中，对坡度的点云进行处理后，导入坡度模型。采用有限元法(FEM)通过区域单元对结构进行建模，采用离散元法(DEM)通过球单元对岩崩和缓冲层进行建模。对岩崩的动态运动进行了跟踪，得到了岩崩对结构的冲击位置和冲击速度。数值计算结果表明，模拟了岩崩运动的三个阶段，即运动、冲击和停滞。落石落在边坡上，冲击岩棚顶部缓冲层，然后反弹到锚固的落石挡土墙(高度低于2 m)，将应力和挠度统一起来，并与落石冲击速度相关联，检验结构的稳定性。此外，落石半径是三个参数(落石形状、落石半径和冲击速度)中的主导参数。虽然该研究侧重于具体的案例研究，但结果为所提出的组合结构在铁路运输保护中的未来应用提供了有价值的指导。
{"title":"Dynamic behavior of new anchor cable ribbed rockfall retaining walls on rock shed: rockfall impact","authors":"Qi Liu, Xianfeng Liu, Jianguo Li, Shengyang Yuan, Peng He, A. Giacomini, O. Buzzi","doi":"10.1680/jgeen.23.00084","DOIUrl":"https://doi.org/10.1680/jgeen.23.00084","url":null,"abstract":"This study investigates the dynamic behavior between a rockfall and a new anchor cable ribbed rockfall retaining walls on a rock shed, which is designed to meet project requirements due to the tremendous space occupation of the protection structure, via numerical simulations by the coupling between PFC3D (discrete element method, DEM) and FLAC3D (finite element method, FEM). In the model, the slope model was imported after the point cloud of the slope was processed. The novel structure is modeled by the finite element method (FEM) through the zone element, while the rockfall and the buffer layer are modeled by the discrete element method (DEM) through the ball element. The dynamic movement of rockfall was traced, and the impact position and velocity were obtained on the structure. The numerical results show that three stages of the rockfall movement were modeled, namely, movement, impact, and stagnation. The rockfall falls on the slope, impacting the buffer layer on the top of the rock shed, before rebounding to the anchored rockfall retaining walls (with a height lower than 2 m). Then, the stress and deflection can be unified and related to the impact velocity of rockfall to examine the stability of the structure. In addition, the rockfall radius is the dominant parameter in the three parameters (rockfall shape, rockfall radius, and impact velocity). While the study focuses on a specific case study, the results provide valuable guidelines for future applications of the proposed combined structure for railway transportation protection.","PeriodicalId":54572,"journal":{"name":"Proceedings of the Institution of Civil Engineers-Geotechnical Engineering","volume":null,"pages":null},"PeriodicalIF":2.2,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138495401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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：