Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.25.6.481
Hao Wu, D. Ma, A. Spearing, G. Zhao
Hazardous failure phenomena such as rock bursts and slabbing failure frequently occur in deep hardrock tunnels, thus understanding the failure phenomena and mechanisms of the stress regime on tunnels is extremely critical. In this study, the tunnel system in a rock mass was physically modelled as a number of scaled openings in rock specimens, and the mechanical behavior of specimens having one to four horseshoe-shaped openings under uniaxial compression were investigated systematically. During the tests, the digital image correlation (DIC) and acoustic emission (AE) techniques were jointly employed to monitor the fracture response of specimens. After which, the stress distributions in the specimens were numerically analyzed and the stress concentration factor on the periphery of the opening was calculated. The results show that the number of openings have a significant impact on the weakening effect of rock mechanical properties. The progressive cracking process of the specimens with openings evolves from first-tensile cracks through second-tensile cracks and spalling cracks to shear cracks, and the crack threshold stresses are measured. Two failure modes are formed: shear failure and shear-tensile failure. According to the stress distribution law around the opening, the crack initiation mechanism can be fully explained. This research provides an insight to failure mechanism of hardrock tunnel.
{"title":"Fracture response and mechanisms of brittle rock with different numbers of openings under uniaxial loading","authors":"Hao Wu, D. Ma, A. Spearing, G. Zhao","doi":"10.12989/GAE.2021.25.6.481","DOIUrl":"https://doi.org/10.12989/GAE.2021.25.6.481","url":null,"abstract":"Hazardous failure phenomena such as rock bursts and slabbing failure frequently occur in deep hardrock tunnels, thus understanding the failure phenomena and mechanisms of the stress regime on tunnels is extremely critical. In this study, the tunnel system in a rock mass was physically modelled as a number of scaled openings in rock specimens, and the mechanical behavior of specimens having one to four horseshoe-shaped openings under uniaxial compression were investigated systematically. During the tests, the digital image correlation (DIC) and acoustic emission (AE) techniques were jointly employed to monitor the fracture response of specimens. After which, the stress distributions in the specimens were numerically analyzed and the stress concentration factor on the periphery of the opening was calculated. The results show that the number of openings have a significant impact on the weakening effect of rock mechanical properties. The progressive cracking process of the specimens with openings evolves from first-tensile cracks through second-tensile cracks and spalling cracks to shear cracks, and the crack threshold stresses are measured. Two failure modes are formed: shear failure and shear-tensile failure. According to the stress distribution law around the opening, the crack initiation mechanism can be fully explained. This research provides an insight to failure mechanism of hardrock tunnel.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66477090","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.26.3.227
F. Huang, Di Wang, N. Xiao, Ruo-chen Ou
The study of failure mode for the soil in front of a shield tunnel face is a key challenge for tunnel engineering, especially when drilling under the water table. This work aims to study face stability of a shield tunnel under the water table based on an blow-out failure mechanism in the framework of the upper bound theorem of limit analysis in conjunction with variational principle. The seepage force in the seepage field is derived, and seepage force is regarded as an external force which is introduced in the upper bound calculation. Based on the failure characteristic of the blow-out failure for the soil in front of a shield tunnel face, a upper bound failure mechanism is constructed. Using this mechanism, the equation of the failure surface is obtained and the shapes of the failure surfaces for different parameters are plotted. By studying the influence of various parameters on the shape of failure surfaces, the changing laws of the shape of the failure surface for different parameters are obtained.
{"title":"Upper bound limit analysis of blow-out failure mode of excavation face of shield tunnel considering groundwater seepage","authors":"F. Huang, Di Wang, N. Xiao, Ruo-chen Ou","doi":"10.12989/GAE.2021.26.3.227","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.3.227","url":null,"abstract":"The study of failure mode for the soil in front of a shield tunnel face is a key challenge for tunnel engineering, especially when drilling under the water table. This work aims to study face stability of a shield tunnel under the water table based on an blow-out failure mechanism in the framework of the upper bound theorem of limit analysis in conjunction with variational principle. The seepage force in the seepage field is derived, and seepage force is regarded as an external force which is introduced in the upper bound calculation. Based on the failure characteristic of the blow-out failure for the soil in front of a shield tunnel face, a upper bound failure mechanism is constructed. Using this mechanism, the equation of the failure surface is obtained and the shapes of the failure surfaces for different parameters are plotted. By studying the influence of various parameters on the shape of failure surfaces, the changing laws of the shape of the failure surface for different parameters are obtained.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66478139","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}
Subgrade loess in arid and semi-arid regions subjected to high-suction conditions owing to low relative humidity and deep groundwater levels. Understanding the hydromechanical behavior of unsaturated compacted loess over a wide suction range is critical for resolving infrastructure problems in such areas. In this study, the water retention behavior of loess was investigated by imposing or measuring suction (s) using the axis translation technique, vapor equilibrium technique, and chilled mirror dew point technique. Triaxial tests were also performed to study the mechanical behavior of compacted loess under different net cell pressures (
{"title":"Hydromechanical behavior and prediction of unsaturated loess over a wide suction range","authors":"Tong Jiang, Zhao Jindi, Junran Zhang, Lijin Wang, Chenyu Song, T. Zhai","doi":"10.12989/GAE.2021.26.3.275","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.3.275","url":null,"abstract":"Subgrade loess in arid and semi-arid regions subjected to high-suction conditions owing to low relative humidity and deep groundwater levels. Understanding the hydromechanical behavior of unsaturated compacted loess over a wide suction range is critical for resolving infrastructure problems in such areas. In this study, the water retention behavior of loess was investigated by imposing or measuring suction (s) using the axis translation technique, vapor equilibrium technique, and chilled mirror dew point technique. Triaxial tests were also performed to study the mechanical behavior of compacted loess under different net cell pressures (","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66478604","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.26.5.441
Chun Zhu, M. He, T. Zhigang, Qingxiang Meng, Xiaohu Zhang
Because of a wide distribution range, sudden occurrence, and high frequency of rockfall disasters on the slope of open-pit mines, it is difficult to effectively control the rockfall disasters in open-pit mines. The slope stabilities of slopes of 13 typical sections in the Changshanhao open-pit mine were calculated using 3DEC software, and the vulnerable area of each slope section was determined. These areas were analyzed as high-incidence areas of rockfalls. Combined with the field geological conditions, the slopes of the W6 and W8 sections where rockfall disasters easily occur were selected to study the motion characteristics of rockfalls, including the trajectory, landing distribution, bouncing height, and total kinetic energy using Rocfall software. According to different distribution characteristics of high-incidence areas of rockfall disasters on a slope, the gravel cushion and protective net methods are proposed to control rockfall disasters. The effectiveness and reasonableness of prevention methods were validated using numerical simulation, proving a good basis for scientific prevention and control of rockfall disasters in open-pit mines.
{"title":"Recognition and prevention of rockfall vulnerable area in open-pit mines based on slope stability analysis","authors":"Chun Zhu, M. He, T. Zhigang, Qingxiang Meng, Xiaohu Zhang","doi":"10.12989/GAE.2021.26.5.441","DOIUrl":"https://doi.org/10.12989/GAE.2021.26.5.441","url":null,"abstract":"Because of a wide distribution range, sudden occurrence, and high frequency of rockfall disasters on the slope of open-pit mines, it is difficult to effectively control the rockfall disasters in open-pit mines. The slope stabilities of slopes of 13 typical sections in the Changshanhao open-pit mine were calculated using 3DEC software, and the vulnerable area of each slope section was determined. These areas were analyzed as high-incidence areas of rockfalls. Combined with the field geological conditions, the slopes of the W6 and W8 sections where rockfall disasters easily occur were selected to study the motion characteristics of rockfalls, including the trajectory, landing distribution, bouncing height, and total kinetic energy using Rocfall software. According to different distribution characteristics of high-incidence areas of rockfall disasters on a slope, the gravel cushion and protective net methods are proposed to control rockfall disasters. The effectiveness and reasonableness of prevention methods were validated using numerical simulation, proving a good basis for scientific prevention and control of rockfall disasters in open-pit mines.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66479322","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.27.1.001
M. Yazici, S. N. Keskin
In some construction works such as multi-basement buildings, subways, deep excavation problems are encountered. In such cases, the shoring walls are used to to prevent damage to the structures next to the excavation area and to provide a safe working environment in the excavation area. In cases where a temporary excavation support is required, sheet pile walls can be more economical comparing to the other walls in the long run due to their reusability. In the present study the analyses were carried out by changing various parametric components such as the number of anchors in vertical row, horizontal and vertical spacing amongst the anchors, anchor angle and excavation depth in LARSSEN type sheet piles constructed temporarily in medium-dense sand. In the analyses, the trapezoidal horizontal earth pressure envelope recommended by FHWA (1999) since the stress concentration occured at the anchor locations. Besides the limit values recommended by FHWA (1999) and BS (1989) was used in the analyses. In total 35488 different sheet pile wall geometry configurations were investigated. According to research results, the lowest costs occur when the horizontal spacing amongst the anchors is 3 m and the angle of the anchors with the horizontal is 150. The lowest costs were obtained when the vertical distance of the uppermost anchor to the ground surface is 3 m. Sheet pile sections with optimum cost were modeled in Plaxis 2D to run displacement analyses. Findings showed that the wall displacements were within the allowable limits commonly used in the literature.
{"title":"Optimum design of multi-anchored larssen type sheet pile wall for temporary construction works","authors":"M. Yazici, S. N. Keskin","doi":"10.12989/GAE.2021.27.1.001","DOIUrl":"https://doi.org/10.12989/GAE.2021.27.1.001","url":null,"abstract":"In some construction works such as multi-basement buildings, subways, deep excavation problems are encountered. In such cases, the shoring walls are used to to prevent damage to the structures next to the excavation area and to provide a safe working environment in the excavation area. In cases where a temporary excavation support is required, sheet pile walls can be more economical comparing to the other walls in the long run due to their reusability. In the present study the analyses were carried out by changing various parametric components such as the number of anchors in vertical row, horizontal and vertical spacing amongst the anchors, anchor angle and excavation depth in LARSSEN type sheet piles constructed temporarily in medium-dense sand. In the analyses, the trapezoidal horizontal earth pressure envelope recommended by FHWA (1999) since the stress concentration occured at the anchor locations. Besides the limit values recommended by FHWA (1999) and BS (1989) was used in the analyses. In total 35488 different sheet pile wall geometry configurations were investigated. According to research results, the lowest costs occur when the horizontal spacing amongst the anchors is 3 m and the angle of the anchors with the horizontal is 150. The lowest costs were obtained when the vertical distance of the uppermost anchor to the ground surface is 3 m. Sheet pile sections with optimum cost were modeled in Plaxis 2D to run displacement analyses. Findings showed that the wall displacements were within the allowable limits commonly used in the literature.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66480489","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.2.129
Shuangxi Feng, Huayang Lei, Xiaodong Ding, G. Zheng, Yawei Jin
The vacuum preloading method has been used in many countries for soil improvement and land reclamation. However, the treatment time is long and the improvement effect is poor for the straight-line vacuum preloading method. To alleviate such problems, a novel combined air booster and straight-line vacuum preloading method for shallow ground treatment is proposed in this study. Two types of traditional vacuum preloading and combined air booster and straight-line vacuum preloading tests were conducted and monitored in the field. In both tests, the depth of prefabricated vertical drains (PVDs) is 4.5m, the distance between PVDs is 0.8m, and the vacuum preloading time is 60 days. The prominent difference between the two methods is when the preloading time is 45 days, the injection pressure of 250 kPa is adopted for combined air booster and straight-line vacuum preloading test to inject air into the ground. Based on the monitoring data, this paper systematically studied the mechanical parameters, hydraulic conductivity, pore water pressure, settlement and subsoil bearing capacity, as determined by the vane shear strength, to demonstrate that the air-pressurizing system can improve the consolidation. The consolidation time decreased by 15 days, the pore water pressure decreased to 60.49%, and the settlement and vane shear strengths increased by 45.31% and 6.29%, respectively, at the surface. These results demonstrate the validity of the combined air booster and straight-line vacuum preloading method. Compared with the traditional vacuum preloading, the combined air booster and straight-line vacuum preloading method has better reinforcement effect. In addition, an estimation method for evaluating the average degree of consolidation and an empirical formula for evaluating the subsoil bearing capacity are proposed to assist in engineering decision making.
{"title":"Shallow ground treatment by a combined air booster and straight-line vacuum preloading method: A case study","authors":"Shuangxi Feng, Huayang Lei, Xiaodong Ding, G. Zheng, Yawei Jin","doi":"10.12989/GAE.2021.24.2.129","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.2.129","url":null,"abstract":"The vacuum preloading method has been used in many countries for soil improvement and land reclamation. However, the treatment time is long and the improvement effect is poor for the straight-line vacuum preloading method. To alleviate such problems, a novel combined air booster and straight-line vacuum preloading method for shallow ground treatment is proposed in this study. Two types of traditional vacuum preloading and combined air booster and straight-line vacuum preloading tests were conducted and monitored in the field. In both tests, the depth of prefabricated vertical drains (PVDs) is 4.5m, the distance between PVDs is 0.8m, and the vacuum preloading time is 60 days. The prominent difference between the two methods is when the preloading time is 45 days, the injection pressure of 250 kPa is adopted for combined air booster and straight-line vacuum preloading test to inject air into the ground. Based on the monitoring data, this paper systematically studied the mechanical parameters, hydraulic conductivity, pore water pressure, settlement and subsoil bearing capacity, as determined by the vane shear strength, to demonstrate that the air-pressurizing system can improve the consolidation. The consolidation time decreased by 15 days, the pore water pressure decreased to 60.49%, and the settlement and vane shear strengths increased by 45.31% and 6.29%, respectively, at the surface. These results demonstrate the validity of the combined air booster and straight-line vacuum preloading method. Compared with the traditional vacuum preloading, the combined air booster and straight-line vacuum preloading method has better reinforcement effect. In addition, an estimation method for evaluating the average degree of consolidation and an empirical formula for evaluating the subsoil bearing capacity are proposed to assist in engineering decision making.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472069","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.2.157
Qiang Zhang, Yanjing Li, Ming Min, B. Jiang
This paper aims at the temperature and slenderness ratio effects on physical and mechanical properties of Beishan granite. A series of uniaxial compression tests with various slenderness ratios and temperatures were carried out, and the acoustic emission signal was also collected. As the temperature increases, the fracture aperture of intercrystalline cracks gradually increases, and obvious transcrystalline cracks occurs when T > 600°C. The failure patterns change from tensile failure mode to ductile failure mode with the increasing temperature. The elastic modulus decreases with the temperature and increases with slenderness ratio, then tends to be a constant value when T = 1000°C. However, the peak strain has the opposite evolution as the elastic modulus under the effects of temperature and slenderness ratio. The uniaxial compression strength (UCS) changes a little for the low-temperature specimens of T < 400°C, but a significant decrease happens when T = 400°C and 800°C due to phase transitions of mineral. The evolution denotes that the critical brittle-ductile transition temperature increases with slenderness ratio, and the critical slenderness ratio corresponding to the characteristic mechanical behavior tends to be smaller with the increasing temperature. Additionally, the AE quantity also increases with temperature in an exponential function.
{"title":"Mechanical behavior of Beishan granite samples with different slenderness ratios at high temperature","authors":"Qiang Zhang, Yanjing Li, Ming Min, B. Jiang","doi":"10.12989/GAE.2021.24.2.157","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.2.157","url":null,"abstract":"This paper aims at the temperature and slenderness ratio effects on physical and mechanical properties of Beishan granite. A series of uniaxial compression tests with various slenderness ratios and temperatures were carried out, and the acoustic emission signal was also collected. As the temperature increases, the fracture aperture of intercrystalline cracks gradually increases, and obvious transcrystalline cracks occurs when T > 600°C. The failure patterns change from tensile failure mode to ductile failure mode with the increasing temperature. The elastic modulus decreases with the temperature and increases with slenderness ratio, then tends to be a constant value when T = 1000°C. However, the peak strain has the opposite evolution as the elastic modulus under the effects of temperature and slenderness ratio. The uniaxial compression strength (UCS) changes a little for the low-temperature specimens of T < 400°C, but a significant decrease happens when T = 400°C and 800°C due to phase transitions of mineral. The evolution denotes that the critical brittle-ductile transition temperature increases with slenderness ratio, and the critical slenderness ratio corresponding to the characteristic mechanical behavior tends to be smaller with the increasing temperature. Additionally, the AE quantity also increases with temperature in an exponential function.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472083","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.3.267
Xiujuan Liang, Haixu Ji
The research presented in this paper deals with dynamic stability analysis of the graphene nanoplatelets (GPLs) reinforced composite spinning disk. The presented small-scaled structure is simulated as a disk covered by viscoelastic substrate which is two-parametric. The centrifugal and Coriolis impacts due to the spinning are taken into account. The stresses and strains would be obtained using the first-order-shear-deformable-theory (FSDT). For Poisson ratio, as well as various amounts of mass densities, the mixture rule is employed, while a modified Halpin-Tsai model is inserted for achieving the elasticity module. The structure's boundary conditions (BCs) are obtained employing GPLs reinforced composite (GPLRC) spinning disk's governing equations applying principle of Hamilton which is based on minimum energy and ultimately have been solved employing numerical approach called generalized-differential quadrature-method (GDQM). Spinning disk's dynamic properties with different boundary conditions (BCs) are explained due to the curves drawn by Matlab software. Also, the simply-supported boundary conditions is applied to edges θ=π/2 and θ= 3π/2, while, cantilever, respectively, is analyzed in R=Ri, and R0. The final results reveal that the GPLs' weight fraction, viscoelastic substrate, various GPLs' pattern, and rotational velocity have a dramatic influence on the amplitude, and vibration behavior of a GPLRC rotating cantilevered disk. As an applicable result in related industries, the spinning velocity impact on the frequency is more effective in the higher radius ratio's amounts.
{"title":"Dynamic stability analysis of a rotary GPLRC disk surrounded by viscoelastic foundation","authors":"Xiujuan Liang, Haixu Ji","doi":"10.12989/GAE.2021.24.3.267","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.3.267","url":null,"abstract":"The research presented in this paper deals with dynamic stability analysis of the graphene nanoplatelets (GPLs) reinforced composite spinning disk. The presented small-scaled structure is simulated as a disk covered by viscoelastic substrate which is two-parametric. The centrifugal and Coriolis impacts due to the spinning are taken into account. The stresses and strains would be obtained using the first-order-shear-deformable-theory (FSDT). For Poisson ratio, as well as various amounts of mass densities, the mixture rule is employed, while a modified Halpin-Tsai model is inserted for achieving the elasticity module. The structure's boundary conditions (BCs) are obtained employing GPLs reinforced composite (GPLRC) spinning disk's governing equations applying principle of Hamilton which is based on minimum energy and ultimately have been solved employing numerical approach called generalized-differential quadrature-method (GDQM). Spinning disk's dynamic properties with different boundary conditions (BCs) are explained due to the curves drawn by Matlab software. Also, the simply-supported boundary conditions is applied to edges θ=π/2 and θ= 3π/2, while, cantilever, respectively, is analyzed in R=Ri, and R0. The final results reveal that the GPLs' weight fraction, viscoelastic substrate, various GPLs' pattern, and rotational velocity have a dramatic influence on the amplitude, and vibration behavior of a GPLRC rotating cantilevered disk. As an applicable result in related industries, the spinning velocity impact on the frequency is more effective in the higher radius ratio's amounts.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472167","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.4.323
Dohyun Kim, Sangseom Jeong
This paper aims to estimate the range of the excavation damaged zone (EDZ) formation caused by the tunnel boring machine (TBM) advancement through dynamic three-dimensional large deformation finite element analysis. Large deformation analysis based on Coupled Eulerian-Lagrangian (CEL) analysis is used to accurately simulate the behavior during TBM excavation. The analysis model is verified based on numerous test results reported in the literature. The range of the formed EDZ will be suggested as a boundary under various conditions – different tunnel diameter, tunnel depth, and rock type. Moreover, evaluation of the integrity of the tunnel structure during excavation has been carried out. Based on the numerical results, the apparent boundary of the EDZ is shown to within the range of 0.7D (D: tunnel diameter) around the excavation surface. Through series of numerical computation, it is clear that for the rock of with higher rock mass rating (RMR) grade (close to 1st grade), the EDZ around the tunnel tends to increase. The size of the EDZ is found to be direct proportional to the tunnel diameter, whereas the depth of the tunnel is inversely proportional to the magnitude of the EDZ. However, the relationship between the formation of the EDZ and the stability of the tunnel was not found to be consistent. In case where the TBM excavation is carried out in hard rock or rock under high confinement (excavation under greater depth), large range of the EDZ may be formed, but less strain occurs along the excavation surface during excavation and is found to be more stable.
{"title":"Estimation of the excavation damage zone in TBM tunnel using large deformation FE analysis","authors":"Dohyun Kim, Sangseom Jeong","doi":"10.12989/GAE.2021.24.4.323","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.4.323","url":null,"abstract":"This paper aims to estimate the range of the excavation damaged zone (EDZ) formation caused by the tunnel boring machine (TBM) advancement through dynamic three-dimensional large deformation finite element analysis. Large deformation analysis based on Coupled Eulerian-Lagrangian (CEL) analysis is used to accurately simulate the behavior during TBM excavation. The analysis model is verified based on numerous test results reported in the literature. The range of the formed EDZ will be suggested as a boundary under various conditions – different tunnel diameter, tunnel depth, and rock type. Moreover, evaluation of the integrity of the tunnel structure during excavation has been carried out. Based on the numerical results, the apparent boundary of the EDZ is shown to within the range of 0.7D (D: tunnel diameter) around the excavation surface. Through series of numerical computation, it is clear that for the rock of with higher rock mass rating (RMR) grade (close to 1st grade), the EDZ around the tunnel tends to increase. The size of the EDZ is found to be direct proportional to the tunnel diameter, whereas the depth of the tunnel is inversely proportional to the magnitude of the EDZ. However, the relationship between the formation of the EDZ and the stability of the tunnel was not found to be consistent. In case where the TBM excavation is carried out in hard rock or rock under high confinement (excavation under greater depth), large range of the EDZ may be formed, but less strain occurs along the excavation surface during excavation and is found to be more stable.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472780","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}
Pub Date : 2021-01-01DOI: 10.12989/GAE.2021.24.4.337
Xing Zheng, B. Shi, Hong-hu Zhu, Chengcheng Zhang, Xing Wang, Mengya Sun
Brillouin Optical Frequency Domain Analysis (BOFDA) is a distributed fiber optic sensing (DFOS) technique that has unique advantages for performance monitoring of piles. However, the complicated production process and harsh operating environment of offshore PHC pipe piles make it difficult to apply this method to pile load testing. In this study, sensing cables were successfully pre-installed into an offshore PHC pipe pile directly for the first time and the BOFDA technique was used for in-situ monitoring of the pile under axial load. High-resolution strain and internal force distributions along the pile were obtained by the BOFDA sensing system. A finite element analysis incorporating the Degradation and Hardening Hyperbolic Model (DHHM) was carried out to evaluate and predict the performance of the pile, which provides an improved insight into the offshore pile-soil interaction mechanism.
{"title":"Performance monitoring of offshore PHC pipe pile using BOFDA-based distributed fiber optic sensing system","authors":"Xing Zheng, B. Shi, Hong-hu Zhu, Chengcheng Zhang, Xing Wang, Mengya Sun","doi":"10.12989/GAE.2021.24.4.337","DOIUrl":"https://doi.org/10.12989/GAE.2021.24.4.337","url":null,"abstract":"Brillouin Optical Frequency Domain Analysis (BOFDA) is a distributed fiber optic sensing (DFOS) technique that has unique advantages for performance monitoring of piles. However, the complicated production process and harsh operating environment of offshore PHC pipe piles make it difficult to apply this method to pile load testing. In this study, sensing cables were successfully pre-installed into an offshore PHC pipe pile directly for the first time and the BOFDA technique was used for in-situ monitoring of the pile under axial load. High-resolution strain and internal force distributions along the pile were obtained by the BOFDA sensing system. A finite element analysis incorporating the Degradation and Hardening Hyperbolic Model (DHHM) was carried out to evaluate and predict the performance of the pile, which provides an improved insight into the offshore pile-soil interaction mechanism.","PeriodicalId":12602,"journal":{"name":"Geomechanics and Engineering","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"66472834","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}
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