The Experts below are selected from a list of 5886 Experts worldwide ranked by ideXlab platform
Peiyuan Lin - One of the best experts on this subject based on the ideXlab platform.
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statistical prediction of deformations of Soil Nail walls
Computers and Geotechnics, 2019Co-Authors: Jie Yuan, Peiyuan Lin, Guoxiong MeiAbstract:Abstract Statistical characterization of model uncertainty has been exclusively focused on reliability-based design of Soil Nail walls against ultimate limit states; little has been accomplished for predictions of horizontal and vertical displacements at the top of the wall for analysis of serviceability limit states. To fill the gap, this study first develops a database containing 461 measured wall horizontal and vertical displacements from 75 fully instrumented Soil Nail walls under working conditions reported in the literature. Then, the database is used to evaluate the accuracies of simplified wall displacement models currently adopted in four national Soil Nail wall design manuals. The results show that on average the current models tend to over-predict displacements for walls in sandy Soils, but under-predict displacements for walls in clayey Soils. Predictions using the current models are moderately to highly dispersive. Simple models are developed and calibrated for prediction of displacements based on the established database. Predictions using the developed models are demonstrated to be accurate on average and significantly less dispersive. In addition, a simple model for prediction of horizontal wall displacement along depth is developed and optimized. The present work is practically valuable for reliability-based design of Soil Nail walls against serviceability limit states.
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calibration of resistance factors for load and resistance factor design of internal limit states of Soil Nail walls
Journal of Geotechnical and Geoenvironmental Engineering, 2019Co-Authors: Peiyuan Lin, Richard J BathurstAbstract:AbstractA general approach for calibration of resistance factors for load and resistance factor design (LRFD) of pullout and tensile failure internal limit states of Soil Nail walls is presented. T...
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Model Uncertainty in Predicting Facing Tensile Forces of Soil Nail Walls Using Bayesian Approach
Hindawi Limited, 2019Co-Authors: Peiyuan LinAbstract:The model uncertainty in prediction of facing tensile forces using the default Federal Highway Administration (FHWA) simplified equation is assessed in this study based on the Bayesian inference method and a large number of measured lower and upper bound facing tensile force data collected from the literature. Model uncertainty was quantified by model bias which is the ratio of measured to nominal facing tensile force. The Bayesian assessment was carried out assuming normal and lognormal distributions of model bias. Based on the collected facing tensile force data, it is shown that both the on-average accuracy and the spread in prediction accuracy of the default FHWA simplified facing tensile force equation depend largely upon the distribution assumptions. Two regression approaches were used to calibrate the default FHWA simplified facing tensile force equation for accuracy improvement. The Bayesian Information Criterion was adopted to quantitatively compare the rationality between the competing normal and lognormal statistical models that were intended for description of model bias. A case study is provided in the end to demonstrate both the importance of model uncertainty and the influence of distribution assumptions on model bias in reliability-based design of Soil Nail walls against facing flexural limit state
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accuracy assessment of default and modified fhwa simplified models for estimation of facing tensile forces of Soil Nail walls
Canadian Geotechnical Journal, 2018Co-Authors: Huifen Liu, Peiyuan Lin, Liansheng Tang, Guoxiong MeiAbstract:The accuracy of the default Federal Highway Administration (FHWA) simplified model for estimation of facing tensile forces for Soil Nail walls under in-service conditions was evaluated using a large number of measured long-term and short-term facing tensile force data collected from the literature. The estimation accuracy was quantified by the mean and coefficient of variation (COV) of the bias where bias is defined as the ratio of measured to calculated facing tensile force. Based on the available data, the default FHWA simplified model equation was found to overestimate long- and short-term facing tensile forces by about 15% and 23% on average, respectively. The corresponding spreads in estimation accuracy expressed as the bias COV were about 43% and 67%. Undesirable correlations between bias values and calculated facing tensile forces using the default FHWA simplified model equation were detected. A modified FHWA simplified model was proposed to improve the on average accuracy, reduce the spread in est...
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statistical evaluation of the fhwa simplified method and modifications for predicting Soil Nail loads
Journal of Geotechnical and Geoenvironmental Engineering, 2017Co-Authors: Peiyuan Lin, Richard J Bathurst, Jinyuan LiuAbstract:AbstractA total of 123 measured maximum Nail-load data were collected from instrumented Soil Nail walls reported in the literature. Filtered data sets corresponding to short-term and long-term measurements were used to evaluate the accuracy of the current Federal Highway Administration (FHWA) simplified method to calculate maximum Nail loads under operational conditions. The accuracy of load predictions was quantified by the mean and coefficient of variation (COV) of the ratio (bias) of measured load to predicted load. Data in short-term and long-term categories were also investigated according to frictional-cohesive and frictional Soil types. Based on the available data, the current FHWA simplified method was found to overestimate both long-term and short-term maximum Nail loads on average. The spreads in prediction accuracy measured by the COV of bias were 38 and 52% for long-term and short-term data, respectively. Large spreads in prediction accuracy were also found using data for walls with cohesive-f...
Wanhuan Zhou - One of the best experts on this subject based on the ideXlab platform.
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estimation of maximum pullout shear stress of grouted Soil Nails using bayesian probabilistic approach
International Journal of Geomechanics, 2013Co-Authors: Wanhuan Zhou, Kaveng YuenAbstract:AbstractThe pullout resistance of Soil Nail is a key parameter in Soil Nailing design. Pullout resistance is affected by many factors, such as overburden pressure, grouting pressure, Soil dilation, and degree of saturation of Soil. Because of the complexity of the pullout mechanism, some factors have not been well incorporated in the current Soil Nail design methods. In this study, Bayesian analysis is performed to investigate the relative importance of several key factors and to build a new design formula to estimate maximum pullout shear stress of grouted Soil Nails. By using a series of laboratory Soil Nail pullout test data, Bayesian analysis is performed to select a predictive formula with suitable complexity and to identify its parameters. It is found that the most important factors are the degree of saturation and the product of grouting pressure and overburden pressure. It is shown that the proposed optimal model exhibits significantly stronger correlation with measurements than the existing effec...
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analytical study on progressive pullout behavior of a Soil Nail
Journal of Geotechnical and Geoenvironmental Engineering, 2012Co-Authors: Chengyu Hong, Wanhuan Zhou, Jian-hua Yin, Huafu PeiAbstract:AbstractDuring the past few decades, Soil Nailing has been widely used for stabilizing slopes and excavations. The Nail-Soil interface shear resistance in the passive zone of a slope or excavation is a critical parameter in design. In this paper, an analytical study is proposed to investigate the progressive pullout response of a Soil Nail. Pullout process is divided into three typical phases: (1) the initial pure elastic phase during which the Nail-Soil interface follows a linear elastic stress-displacement relationship; (2) the elastic-plastic phase during which a transition point presents dividing the elastic and plastic zones; and (3) the final pure plastic phase. A comparison study between calculations and laboratory test data are presented to examine the effectiveness of the method. In addition, a comprehensive parametric study is performed to assess the effects of several key factors on the pullout resistance of a Soil Nail. These factors include the length and diameter, length of plastic zone, and...
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Finite element modelling of pullout testing on a Soil Nail in a pullout box under different overburden and grouting pressures
Canadian Geotechnical Journal, 2011Co-Authors: Wanhuan Zhou, Chengyu HongAbstract:In this paper, a three-dimensional (3D) finite element (FE) model is developed to simulate the pullout behaviour of a Soil Nail in a Soil-Nail pullout box under different overburden and grouting pressures. The FE model simulates all the procedures of a pullout test on a grouted Soil Nail in a compacted and saturated completely decomposed granite (CDG) Soil. The stress-strain behaviour of the CDG Soil is described by a modified Drucker-Prager/Cap model, while that of the Soil- Nail interface is represented by the Coulomb friction model. Triaxial experiment data are used to calibrate the Soil parame- ters in the Soil constitutive model. The interface parameters are determined from back-analysis with the laboratory Soil-Nail pullout data. The Soil stress variations surrounding the Soil Nail during drilling, grouting, saturation, and pullout are all well simulated by the FE modelling and compared with available test data. The comparisons between the modelling and experi- mental data have shown that the established FE can well simulate the pullout behaviour of a Soil Nail in a Soil mass. Based on this, the verified FE model has the potential to simulate the performance of a Soil Nail in a field Soil slope.
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influences of overburden pressure and Soil dilation on Soil Nail pull out resistance
Computers and Geotechnics, 2010Co-Authors: Lijun Su, Wanhuan ZhouAbstract:Abstract Soil Nailing is the most popular technique for stabilizing newly formed and existing sub-standard slopes in Hong Kong because of its economic and technical advantages. The Nail–Soil interface shear resistance is an important parameter in design of Soil Nailed structures. A three-dimensional finite element model was established and used for simulating Soil Nail pull-out tests. The finite element model was verified by comparing simulated results with measured data. The agreement between the experimental and simulated results in terms of both average pull-out shear stress and stress variation was very good. Using this finite element model, a parametric study was carried out to study the influences of the overburden pressure and Soil dilation angle on the Soil Nail pull-out resistance. The simulated peak pull-out resistance was not directly related to the overburden pressure, which was coincident with the observations in laboratory pull-out tests. The simulated pull-out resistance increased significantly with the increase in dilation angle of the shearing zone. This analysis indicated that the constrained dilatancy of the Nail–Soil interface and the Soil surrounding the Nail contributed a lot to the development of peak pull-out resistance.
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comparative study on the elongation measurement of a Soil Nail using optical lower coherence interferometry method and fbg method
Advances in Structural Engineering, 2010Co-Authors: Chengyu Hong, Wanhuan Zhou, Jian-hua Yin, Wei Jin, Chao Wang, Honghu ZhuAbstract:Optical fiber sensor has gained popularity for structural monitoring in recent decades. Studies on the monitoring for geotechnical structures with fully-distributed fiber sensors, however, are quite limited. In this study, the fully-distributed Lower Coherence Interferometry (LCI) sensors and quasi-distributed Fiber Bragg Grating (FBG) sensors are applied for measuring the strain distribution of a Soil Nail as a slender structure during pullout test. First, this paper introduces an innovative calibration method for the LCI system. Second, the paper describes the procedures of fiber instrumentation on Soil Nail. Third, the measured results by LCI technology and FBG technology are compared to study the strain distribution and friction resistance of Soil Nail during pullout test. Comparative study from test results indicates the characteristics of strain distribution and resistance contribution for different parts of Soil Nail. Through this study, the advantages and limitations of two sensing technologies ar...
Jinyuan Liu - One of the best experts on this subject based on the ideXlab platform.
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statistical evaluation of the fhwa simplified method and modifications for predicting Soil Nail loads
Journal of Geotechnical and Geoenvironmental Engineering, 2017Co-Authors: Peiyuan Lin, Richard J Bathurst, Jinyuan LiuAbstract:AbstractA total of 123 measured maximum Nail-load data were collected from instrumented Soil Nail walls reported in the literature. Filtered data sets corresponding to short-term and long-term measurements were used to evaluate the accuracy of the current Federal Highway Administration (FHWA) simplified method to calculate maximum Nail loads under operational conditions. The accuracy of load predictions was quantified by the mean and coefficient of variation (COV) of the ratio (bias) of measured load to predicted load. Data in short-term and long-term categories were also investigated according to frictional-cohesive and frictional Soil types. Based on the available data, the current FHWA simplified method was found to overestimate both long-term and short-term maximum Nail loads on average. The spreads in prediction accuracy measured by the COV of bias were 38 and 52% for long-term and short-term data, respectively. Large spreads in prediction accuracy were also found using data for walls with cohesive-f...
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Analysis of resistance factors for LFRD of Soil Nail walls against external stability failures
Acta Geotechnica, 2017Co-Authors: Peiyuan Lin, Jinyuan LiuAbstract:This paper presents reliability analyses of Soil Nail walls against two external ultimate limit states, global and sliding stabilities, which are related to the external stability failures of Soil Nail walls. Reliability analyses are conducted using Monte Carlo simulation technique. Soil Nailing is a popular retaining system in highway construction and slope stabilization, and its current design practice is still based on the working stress design. There remains a need to establish a more rational design framework—load and resistance factor design—based on the concept of limit state design and reliability analysis for Soil Nail walls. The development of load and resistance factor design approach must consider multiple ultimate limit states, associated with external, internal, and facing failures. The analyses of resistance factors against two external failures are conducted in this study considering various influencing factors, including statistical parameters of Soil friction angle, ultimate bond strength between Soil and Nails, Soil type, wall geometry (wall height, back slope angle, and face batter angle), and Nail configurations (Nail inclination angle, drillhole diameter, and Nail spacing). In the end, a series of resistance factors are proposed for potential application of load and resistance factor design approach against external failures for Soil Nail walls according to different design codes.
Jian-hua Yin - One of the best experts on this subject based on the ideXlab platform.
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evaluations of load deformation behavior of Soil Nail using hyperbolic pullout model
Geomechanics and Engineering, 2014Co-Authors: Chengcheng Zhang, Honghu Zhu, Bin Shi, Jian-hua YinAbstract:Soil Nailing, as an effective stabilizing method for slopes and excavations, has been widely used worldwide. However, the interaction mechanism of a Soil Nail and the surrounding Soil and its influential factors are not well understood. A pullout model using a hyperbolic shear stress-shear strain relationship is proposed to describe the load-deformation behavior of a cement grouted Soil Nail. Numerical analysis has been conducted to solve the governing equation and the distribution of tensile force along the Nail length is investigated through a parametric study. The simulation results are highly consistent with laboratory Soil Nail pullout test results in the literature, indicating that the proposed model is efficient and accurate. Furthermore, the effects of key parameters, including normal stress, degree of saturation of Soil, and surface roughness of Soil Nail, on the model parameters are studied in detail.
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analytical study on progressive pullout behavior of a Soil Nail
Journal of Geotechnical and Geoenvironmental Engineering, 2012Co-Authors: Chengyu Hong, Wanhuan Zhou, Jian-hua Yin, Huafu PeiAbstract:AbstractDuring the past few decades, Soil Nailing has been widely used for stabilizing slopes and excavations. The Nail-Soil interface shear resistance in the passive zone of a slope or excavation is a critical parameter in design. In this paper, an analytical study is proposed to investigate the progressive pullout response of a Soil Nail. Pullout process is divided into three typical phases: (1) the initial pure elastic phase during which the Nail-Soil interface follows a linear elastic stress-displacement relationship; (2) the elastic-plastic phase during which a transition point presents dividing the elastic and plastic zones; and (3) the final pure plastic phase. A comparison study between calculations and laboratory test data are presented to examine the effectiveness of the method. In addition, a comprehensive parametric study is performed to assess the effects of several key factors on the pullout resistance of a Soil Nail. These factors include the length and diameter, length of plastic zone, and...
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comparative study on the elongation measurement of a Soil Nail using optical lower coherence interferometry method and fbg method
Advances in Structural Engineering, 2010Co-Authors: Chengyu Hong, Wanhuan Zhou, Jian-hua Yin, Wei Jin, Chao Wang, Honghu ZhuAbstract:Optical fiber sensor has gained popularity for structural monitoring in recent decades. Studies on the monitoring for geotechnical structures with fully-distributed fiber sensors, however, are quite limited. In this study, the fully-distributed Lower Coherence Interferometry (LCI) sensors and quasi-distributed Fiber Bragg Grating (FBG) sensors are applied for measuring the strain distribution of a Soil Nail as a slender structure during pullout test. First, this paper introduces an innovative calibration method for the LCI system. Second, the paper describes the procedures of fiber instrumentation on Soil Nail. Third, the measured results by LCI technology and FBG technology are compared to study the strain distribution and friction resistance of Soil Nail during pullout test. Comparative study from test results indicates the characteristics of strain distribution and resistance contribution for different parts of Soil Nail. Through this study, the advantages and limitations of two sensing technologies ar...
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Influence of Overburden Pressure on Soil — Nail Pullout Resistance in a Compacted Fill
Journal of Geotechnical and Geoenvironmental Engineering, 2008Co-Authors: Terence C F Chan, Y K Shiu, Jian-hua Yin, S L ChiuAbstract:Soil Nailing has been widely used in many places in the world in the last two decades because of its technical and economical advantages. The Nail–Soil interface shear strength is an important parameter in Soil Nail design. This parameter is governed by a number of factors, among which the influence of the overburden pressure (or Soil depth) is the most controversial. There are differing views concerning the effect of overburden on the Nail–Soil interface shear strength. In order to examine the influence of the overburden pressure, a series of laboratory pullout tests on Soil Nails installed in compacted completely decomposed granite fill have been conducted using two pullout boxes. Numerical simulations have also been carried out and the results are compared with the pullout test data. The procedures of the pullout tests and new features of the pullout boxes used are briefly described. Changes of the vertical stress in Soil close to the Nail throughout the course of Soil Nail installation and pullout are...
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a simple mathematical model for Soil Nail and Soil interaction analysis
Computers and Geotechnics, 2008Co-Authors: Wanhuan Zhou, Jian-hua YinAbstract:Abstract Soil Nails have been widely used to stabilize slopes and earth retaining structures in many countries and regions, especially, in Hong Kong. The analysis of the interaction between a Soil Nail and the surrounding Soil is of great interests to both design engineers and researchers. In this paper, authors present a simple mathematical model for the interaction analysis of a Soil Nail and the surrounding Soil considering a few key factors which are Soil dilation, bending of the Soil Nail, vertical pressure, and non-linear subgrade reaction stiffness. The lateral subgrade reaction between the Soil and the Soil Nail is assumed to obey a hyperbolic relation. Reported test data in the literature are used to verify the present model. The contributions of the Soil-Nail bending on the pull-out resistance are evaluated in two case studies.
Vikas Pratap Singh - One of the best experts on this subject based on the ideXlab platform.
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Soil Nails field pullout testing: evaluation and applications
International Journal of Geotechnical Engineering, 2013Co-Authors: G. Babu, Vikas Pratap SinghAbstract:AbstractField pullout testing of Soil Nails is identified as the appropriate method for studying the Nail-Soil interaction and assessing the performance of Soil Nail walls. The primary objective of this study is to highlight the importance and practical applications of field pullout tests in the design and performance assessment of Soil Nail walls. Bond strength of Soil-Nail interface is the essential parameter in the design of Soil Nail walls. Field pullout tests provide valuable inputs for the selection of appropriate design bond strength. In this paper, a reliability based methodology for the evaluation and selection of appropriate field pullout tests is proposed for the determination of the design bond strength. The proposed methodology is illustrated with reference to the field pullout tests on Soil Nails conducted at a local site.
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2D Numerical Simulations of Soil Nail Walls
Geotechnical and Geological Engineering, 2010Co-Authors: Vikas Pratap Singh, G. L. Sivakumar BabuAbstract:In practice, numerical simulations of Soil Nail walls are often carried out to assess the performance and stability. In the present study, implications of the use of advanced Soil models, such as hardening Soil model and hardening Soil with small-strain stiffness model to simulate the behavior of in situ Soil on the overall response of simulated Soil Nail wall have been studied, and compared with respect to the analysis using conventional and most prevalently used Mohr-Coulomb Soil model. Further, influence of the consideration of bending stiffness of Soil Nails on the simulation results has been examined. Results of the simulations indicated that the use of advanced models is desirable for cases of Soil Nail walls constructed in soft Soils and when lateral wall displacements are critical to the adjoining structures. Incorporation of bending stiffness of Nails is found important from the consideration of facing failure modes of Soil Nail walls.
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Reliability analysis of Soil Nail walls
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards, 2009Co-Authors: G. L. Sivakumar Babu, Vikas Pratap SinghAbstract:In India, Soil Nail walls are being extensively used for supporting vertical excavations below ground level to accommodate construction of one-or two-storied basements. Generally, the depth of excavations for basement construction ranges from 10 m to 15 m. For such large depth of excavation, variability of in-situ Soil properties has significant influence on the stability of the Soil Nail walls. In the present study, using reliability analysis, an attempt is made to study the influence of variability of in-situ Soil properties on the stability of Soil Nail walls. For better understanding, a case of 10 m high Soil Nail wall constructed to support a vertical cut is considered for the study and its stability is evaluated for various failure modes. Additionally, the influence of correlation among Soil parameters on Soil Nail wall stability is assessed. In-situ Soil friction angle and correlation between in-situ Soil cohesion and angle of friction are found to influence Soil Nail wall stability significantly. ...
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numerical analysis of performance of Soil Nail walls in seismic conditions
2007Co-Authors: Vikas Pratap SinghAbstract:Evidences from the field and full-scale laboratory tests suggest that Soil Nail walls perform remarkably well under seismic conditions. In this study an attempt has been made to study the performance of a Soil Nail wall supporting a vertical cut of 8 m height under seismic conditions. The wall is designed in conventional manner by using the allowable stress design procedure. The response of the wall is then simulated numerically by using a finite element analysis. Seismic data from Bhuj and Uttarkashi earthquakes is used for the pseudo-static and dynamic analyses. To assess the performance of the Soil Nail wall, parameters such as maximum lateral displacements, development of Nail forces, important failure modes of Soil Nail walls, have been studied under both static and seismic conditions. Results of the numerical analyses indicate that the use of Soil Nail walls is desirable to impart stability to the retaining systems under seismic conditions.
