The thermo-mechanical behaviour of saturated and unsaturated soil-structure interfaces plays a key role in analysing the performance of energy piles. Previous studies focused on saturated interfaces and did not investigate the coupled effects of temperature and suction on interface behaviour. In this study, a clayey sand-structure interface with a normalised roughness of one was tested through a new temperature- and suction-controlled direct shear apparatus. A variety of temperatures (8, 20 and 42 °C), net normal stresses (25, 50, 100, 150, 225 and 300 kPa) and suctions (0, 50 and 200 kPa) were considered. The results show that temperature can have a minor impact on the friction angle, whose value at 42 °C is smaller by about 2.2° than that at 8 °C, likely because heating can reduce the shearing-induced contraction in the shear zone. More importantly, the interface strength increases nonlinearly with increasing suction, and the incremental rate is temperature-dependent. Heating the interface at a net normal stress of 50 kPa reduces this incremental rate due to surface tension reduction and thermally-induced changes in soil fabric. In contrast, this incremental rate increases at a net normal stress of 150 kPa with the same temperature increment, probably because the heated specimen has more small-size pores due to thermal contraction and more menisci water lenses, whose influence outweighs the effects of surface tension.
{"title":"Coupled effects of temperature and suction on the shear behaviour of saturated and unsaturated clayey sand-structure interfaces","authors":"She-Qiang Cui, Chao Zhou, Qingyi Mu, Hua-Fu Pei, Jian-Hua Yin","doi":"10.1680/jgeot.22.00404","DOIUrl":"https://doi.org/10.1680/jgeot.22.00404","url":null,"abstract":"The thermo-mechanical behaviour of saturated and unsaturated soil-structure interfaces plays a key role in analysing the performance of energy piles. Previous studies focused on saturated interfaces and did not investigate the coupled effects of temperature and suction on interface behaviour. In this study, a clayey sand-structure interface with a normalised roughness of one was tested through a new temperature- and suction-controlled direct shear apparatus. A variety of temperatures (8, 20 and 42 °C), net normal stresses (25, 50, 100, 150, 225 and 300 kPa) and suctions (0, 50 and 200 kPa) were considered. The results show that temperature can have a minor impact on the friction angle, whose value at 42 °C is smaller by about 2.2° than that at 8 °C, likely because heating can reduce the shearing-induced contraction in the shear zone. More importantly, the interface strength increases nonlinearly with increasing suction, and the incremental rate is temperature-dependent. Heating the interface at a net normal stress of 50 kPa reduces this incremental rate due to surface tension reduction and thermally-induced changes in soil fabric. In contrast, this incremental rate increases at a net normal stress of 150 kPa with the same temperature increment, probably because the heated specimen has more small-size pores due to thermal contraction and more menisci water lenses, whose influence outweighs the effects of surface tension.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"48 18","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139442448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A cavity expansion-based method is proposed in this paper to correlate the relevant findings with the piezocone penetration test (CPTu) data in clays. The rigorous and explicit solution for both spherical and cylindrical undrained cavity expansion is adopted based on a unified critical state constitutive model for clays and sands. The developed analogous model is comprehensively validated against two series of advanced numerical simulations and calibration chamber tests of the CPTu in fine-grained soils, along with bias analyses. The effects of the over-consolidation ratio and initial state parameter are extensively investigated for various clay types. Both theoretical and empirical correlations are then proposed for back-calculations of cone factor, undrained shear strength, over-consolidation ratio and initial state parameter of clays. Two case studies of CPTu tests are additionally conducted to examine correlations and contours of in-situ state parameter, demonstrating the applicability of the proposed theoretical approach for interpretation of the CPTu data.
{"title":"Cavity expansion-based interpretation of piezocone penetration test (CPTu) data in clays","authors":"Pin‐Qiang Mo, Guojun Cai, Kuan-Jun Wang, Abolfazl Eslami, Hai-Sui Yu","doi":"10.1680/jgeot.23.00045","DOIUrl":"https://doi.org/10.1680/jgeot.23.00045","url":null,"abstract":"A cavity expansion-based method is proposed in this paper to correlate the relevant findings with the piezocone penetration test (CPTu) data in clays. The rigorous and explicit solution for both spherical and cylindrical undrained cavity expansion is adopted based on a unified critical state constitutive model for clays and sands. The developed analogous model is comprehensively validated against two series of advanced numerical simulations and calibration chamber tests of the CPTu in fine-grained soils, along with bias analyses. The effects of the over-consolidation ratio and initial state parameter are extensively investigated for various clay types. Both theoretical and empirical correlations are then proposed for back-calculations of cone factor, undrained shear strength, over-consolidation ratio and initial state parameter of clays. Two case studies of CPTu tests are additionally conducted to examine correlations and contours of in-situ state parameter, demonstrating the applicability of the proposed theoretical approach for interpretation of the CPTu data.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"36 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139451217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Discussion on Cavity expansion in cohesive frictional soils with limited dilation by Carter and Yu (2022)","authors":"John P. Carter, Hai-Sui Yu, Hongyu Qin, Kang Fei","doi":"10.1680/jgeot.22.00069","DOIUrl":"https://doi.org/10.1680/jgeot.22.00069","url":null,"abstract":"","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"40 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138999072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Both liquefaction resistance of granular materials under complex multidirectional cyclic loadings and influence of particle form or morphology on it are poorly understood. This paper presents an experimental investigation on this topic. Round, frosted, concave, and convex glass beads as well as Hong Kong CDG sand were used to prepare samples with varying particle morphologies (i.e., roughness, sphericity, aspect ratio and convexity). Unidirectional and multidirectional cyclic simple shear tests were performed to examine the liquefaction susceptibility and highlight the specific role of various particle morphologies. Results show that the increase of shape irregularity and surface roughness both result in a considerable liquefaction resistance improvement. Moreover, overall shape has a more fundamental effect on liquefaction behaviour than surface roughness. An enhanced morphology index, providing a collective description for the particle geometry and surface texture, are proposed to optimize the correlation with liquefaction behaviour. Besides, it is discovered that multidirectional loading could exacerbate the generation of pore pressure and trigger a sharp increase in shear strain amplitude at a lower excess pore pressure ratio. Accordingly, a novel analytical procedure for estimating the liquefaction resistance independent of cyclic loading patterns and particle morphology is developed and validated by additional data in literature.
{"title":"Cyclic liquefaction of granular materials with varied forms under multidirectional loads","authors":"Shao-Heng He, Zhen-Yu Yin, Zhi Ding","doi":"10.1680/jgeot.22.00386","DOIUrl":"https://doi.org/10.1680/jgeot.22.00386","url":null,"abstract":"Both liquefaction resistance of granular materials under complex multidirectional cyclic loadings and influence of particle form or morphology on it are poorly understood. This paper presents an experimental investigation on this topic. Round, frosted, concave, and convex glass beads as well as Hong Kong CDG sand were used to prepare samples with varying particle morphologies (i.e., roughness, sphericity, aspect ratio and convexity). Unidirectional and multidirectional cyclic simple shear tests were performed to examine the liquefaction susceptibility and highlight the specific role of various particle morphologies. Results show that the increase of shape irregularity and surface roughness both result in a considerable liquefaction resistance improvement. Moreover, overall shape has a more fundamental effect on liquefaction behaviour than surface roughness. An enhanced morphology index, providing a collective description for the particle geometry and surface texture, are proposed to optimize the correlation with liquefaction behaviour. Besides, it is discovered that multidirectional loading could exacerbate the generation of pore pressure and trigger a sharp increase in shear strain amplitude at a lower excess pore pressure ratio. Accordingly, a novel analytical procedure for estimating the liquefaction resistance independent of cyclic loading patterns and particle morphology is developed and validated by additional data in literature.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138542098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The hysteresis observed in the water retention curve was experimentally studied through the use of X-ray micro-computed tomography. The CT images were acquired during the main drying and wetting processes of a water retention test for uniform sand. The porosity and degree of saturation (Sr) of pore-scale local subsets were calculated using images segmented into soil, water, and air phases. The simultaneous distribution of the local porosity and Sr was also analysed to investigate the relationship between the pore size and retained water volume. At similar suction levels, only small pore spaces retained water during wetting, while relatively large pore spaces retained water during drying, demonstrating the ink-bottle effect. At similar saturation levels, the simultaneous distribution was independent of the wetting and drying processes, indicating no significant difference in the water retention state between the two processes. Another image analysis was performed to calculate the principal curvatures of the air-water interface. At similar saturation levels, the calculated curvature of the drying process was greater than that of the wetting process, indicating contact angle hysteresis. The contact angle between the soil particles and water is different at the microscopic level, whereas the water retention states of the two processes are similar.
{"title":"A microscopic interpretation of hysteresis in the water retention curve of sand","authors":"Yosuke Higo, Ryunosuke Kido","doi":"10.1680/jgeot.23.00084","DOIUrl":"https://doi.org/10.1680/jgeot.23.00084","url":null,"abstract":"The hysteresis observed in the water retention curve was experimentally studied through the use of X-ray micro-computed tomography. The CT images were acquired during the main drying and wetting processes of a water retention test for uniform sand. The porosity and degree of saturation (Sr) of pore-scale local subsets were calculated using images segmented into soil, water, and air phases. The simultaneous distribution of the local porosity and Sr was also analysed to investigate the relationship between the pore size and retained water volume. At similar suction levels, only small pore spaces retained water during wetting, while relatively large pore spaces retained water during drying, demonstrating the ink-bottle effect. At similar saturation levels, the simultaneous distribution was independent of the wetting and drying processes, indicating no significant difference in the water retention state between the two processes. Another image analysis was performed to calculate the principal curvatures of the air-water interface. At similar saturation levels, the calculated curvature of the drying process was greater than that of the wetting process, indicating contact angle hysteresis. The contact angle between the soil particles and water is different at the microscopic level, whereas the water retention states of the two processes are similar.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Trung Ngo, Buddhima Indraratna, Matthew Coop, Yujie Qi
During the passage of trains, dynamic impact loads caused by wheel imperfections or rail abnormalities cause significant ballast degradation. In this study, the use of rubber mats manufactured from recycled tyres placed underneath a ballast layer is investigated to mitigate the adverse effects of impact loads. Based on a series of tests conducted using a high-capacity drop-weight facility to evaluate the dynamic impact responses, the experimental results show that the inclusion of a rubber mat beneath the ballast assembly significantly reduces particle breakage. This study also describes a numerical analysis following a coupled discrete-continuum modelling approach to examine the complex interaction of discrete ballast grains with the recycled rubber mat. In particular, a mathematical framework coupling the discrete and continuum domains is developed to facilitate the exchange of forces and displacements at the ballast-mat interface. Laboratory data measured from large-scale impact tests are used to calibrate and validate this coupled model. Subsequently, the model is used to predict the deformation and breakage of ballast, contact force distributions, impact forces, coordination numbers and the evolution of energy components during impact testing. The energy-absorbing properties of the rubber mat are captured in terms of reducing particle breakage from a micro-mechanical perspective.
{"title":"Influence of recycled rubber mat on the behaviour of ballast under impact loading: experimental and numerical modelling","authors":"Trung Ngo, Buddhima Indraratna, Matthew Coop, Yujie Qi","doi":"10.1680/jgeot.23.00073","DOIUrl":"https://doi.org/10.1680/jgeot.23.00073","url":null,"abstract":"During the passage of trains, dynamic impact loads caused by wheel imperfections or rail abnormalities cause significant ballast degradation. In this study, the use of rubber mats manufactured from recycled tyres placed underneath a ballast layer is investigated to mitigate the adverse effects of impact loads. Based on a series of tests conducted using a high-capacity drop-weight facility to evaluate the dynamic impact responses, the experimental results show that the inclusion of a rubber mat beneath the ballast assembly significantly reduces particle breakage. This study also describes a numerical analysis following a coupled discrete-continuum modelling approach to examine the complex interaction of discrete ballast grains with the recycled rubber mat. In particular, a mathematical framework coupling the discrete and continuum domains is developed to facilitate the exchange of forces and displacements at the ballast-mat interface. Laboratory data measured from large-scale impact tests are used to calibrate and validate this coupled model. Subsequently, the model is used to predict the deformation and breakage of ballast, contact force distributions, impact forces, coordination numbers and the evolution of energy components during impact testing. The energy-absorbing properties of the rubber mat are captured in terms of reducing particle breakage from a micro-mechanical perspective.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"57 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study presents two methods of producing an insoluble biopolymer, the microbially induced biopolymer formation (MIBF) and enzyme-induced biopolymer formation (EIBF) and explores their ability to reduce hydraulic conductivity and cause bioclogging in soil from pore to column scales. The batch experiments confirm that insoluble polysaccharidic biopolymers, dextran, are successfully produced either by the model bacteria or by the extracted cell-free enzyme. The results show that the EIBF method is more efficient in producing biopolymer and reducing hydraulic conductivity compared to the MIBF method. This study also uses microfluidic chips, which reveals the pore-filling behavior of biopolymers produced by both methods. EIBF produces larger dextran flocs than MIBF, and hence EIBF lowers the hydraulic conductivity more than MIBF for a given pore occupancy of dextran. Column experiments demonstrate that both MIBF and EIBF can significantly lower the hydraulic conductivity of coarse sands by two orders of magnitude with only 3% biopolymer pore saturation. The presented results suggest that both methods have the potential to induce well-controlled, engineered bioclogging in coarse-grained soils, and have applications in various geotechnical practices, such as sealing leakage in water-front structures, installing hydraulic barriers, and mitigating soil erosion.
{"title":"Engineered bioclogging in sands: comparison of microbially induced and enzyme-induced biopolymer formation","authors":"Yong-Min Kim, Tae-Hyuk Kwon","doi":"10.1680/jgeot.23.00039","DOIUrl":"https://doi.org/10.1680/jgeot.23.00039","url":null,"abstract":"This study presents two methods of producing an insoluble biopolymer, the microbially induced biopolymer formation (MIBF) and enzyme-induced biopolymer formation (EIBF) and explores their ability to reduce hydraulic conductivity and cause bioclogging in soil from pore to column scales. The batch experiments confirm that insoluble polysaccharidic biopolymers, dextran, are successfully produced either by the model bacteria or by the extracted cell-free enzyme. The results show that the EIBF method is more efficient in producing biopolymer and reducing hydraulic conductivity compared to the MIBF method. This study also uses microfluidic chips, which reveals the pore-filling behavior of biopolymers produced by both methods. EIBF produces larger dextran flocs than MIBF, and hence EIBF lowers the hydraulic conductivity more than MIBF for a given pore occupancy of dextran. Column experiments demonstrate that both MIBF and EIBF can significantly lower the hydraulic conductivity of coarse sands by two orders of magnitude with only 3% biopolymer pore saturation. The presented results suggest that both methods have the potential to induce well-controlled, engineered bioclogging in coarse-grained soils, and have applications in various geotechnical practices, such as sealing leakage in water-front structures, installing hydraulic barriers, and mitigating soil erosion.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"80 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Domenico Gallese, Davide Noè Gorini, Luigi Callisto
Integral abutment bridges are characterised by a monolithic connection between the deck and the abutments. Because of this connection, the seismic behaviour of the entire structure tends to be controlled by its interaction with the surrounding soil, and especially with the approach embankments. To date, methods for the seismic design of this type of bridges are still characterised by substantial uncertainties, mostly because insufficient understanding of the dynamic response of the soil-structure system. This paper provides a contribution to the interpretation of the seismic behaviour of integral abutment bridges, focusing on a single-span structural scheme that has been receiving significant attention in recent years. The dynamic interaction between the bridge and the soil is studied with global numerical models of the soil-bridge system developed in OpenSees and subjected to a variety of ground motions. The results of the dynamic simulations, interpreted also with the aid of a modal analysis of the system, are used to develop and finally validate a simplified design procedure, based on the capacity spectrum method, aimed at evaluating the maximum deformation and internal forces in the structure produced by the longitudinal component of the seismic motion, that typically dominates the design of integral bridges.
{"title":"A nonlinear static analysis for the seismic design of single-span integral abutment bridges","authors":"Domenico Gallese, Davide Noè Gorini, Luigi Callisto","doi":"10.1680/jgeot.22.00229","DOIUrl":"https://doi.org/10.1680/jgeot.22.00229","url":null,"abstract":"Integral abutment bridges are characterised by a monolithic connection between the deck and the abutments. Because of this connection, the seismic behaviour of the entire structure tends to be controlled by its interaction with the surrounding soil, and especially with the approach embankments. To date, methods for the seismic design of this type of bridges are still characterised by substantial uncertainties, mostly because insufficient understanding of the dynamic response of the soil-structure system. This paper provides a contribution to the interpretation of the seismic behaviour of integral abutment bridges, focusing on a single-span structural scheme that has been receiving significant attention in recent years. The dynamic interaction between the bridge and the soil is studied with global numerical models of the soil-bridge system developed in OpenSees and subjected to a variety of ground motions. The results of the dynamic simulations, interpreted also with the aid of a modal analysis of the system, are used to develop and finally validate a simplified design procedure, based on the capacity spectrum method, aimed at evaluating the maximum deformation and internal forces in the structure produced by the longitudinal component of the seismic motion, that typically dominates the design of integral bridges.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"85 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Underwater tunnels are often subject to groundwater infiltration, which can pose risks to both the tunnel's safety and the groundwater environment. Analytical solutions are commonly used to estimate the rate of water infiltration in tunnels. However, there is a lack of research on the analytical solution of tunnels with drainage systems. This study aimed to investigate groundwater seepage in tunnels with circumferentially arranged drainage pipes. The analytical formula for estimating the inflow rate takes into account the seepage processes in the ground, primary lining, and geotextile. The accuracy of the analytical solution is confirmed by comparing it with numerical results. The analytical solution's general form is simplified for tunnels with varying permeabilities of the surrounding strata and geotextiles, and a query chart is created to facilitate engineering applications. The research findings can serve as a theoretical basis and reference for the establishment of relevant specifications and the design of tunnel drainage systems.
{"title":"Water infiltration in drained circular tunnels: an analytical solution and its simplification","authors":"Bi Jinfeng, Jiang Hong","doi":"10.1680/jgeot.23.00040","DOIUrl":"https://doi.org/10.1680/jgeot.23.00040","url":null,"abstract":"Underwater tunnels are often subject to groundwater infiltration, which can pose risks to both the tunnel's safety and the groundwater environment. Analytical solutions are commonly used to estimate the rate of water infiltration in tunnels. However, there is a lack of research on the analytical solution of tunnels with drainage systems. This study aimed to investigate groundwater seepage in tunnels with circumferentially arranged drainage pipes. The analytical formula for estimating the inflow rate takes into account the seepage processes in the ground, primary lining, and geotextile. The accuracy of the analytical solution is confirmed by comparing it with numerical results. The analytical solution's general form is simplified for tunnels with varying permeabilities of the surrounding strata and geotextiles, and a query chart is created to facilitate engineering applications. The research findings can serve as a theoretical basis and reference for the establishment of relevant specifications and the design of tunnel drainage systems.","PeriodicalId":501472,"journal":{"name":"Géotechnique","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138535436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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：