The foundations of some ocean engineering structures are built to withstand not only the vertical gravity load V, but also the horizontal load H induced by sea waves and current. The horizontal load includes the conce...The foundations of some ocean engineering structures are built to withstand not only the vertical gravity load V, but also the horizontal load H induced by sea waves and current. The horizontal load includes the concentrated force load, the moment load M, and the torque load T termed also as combined loading. It is of academic and engineering significance to study the deformation law of submarine seabed due to combined loading. On the basis of the three-dimensional elastic mechanics solution of circular foundation, numerical methods are used to analyze the deformation law of submarine soil under circular foundation with six degrees of freedom. The finite element analysis results give the elastic deformation law of soil in three dimensional spaces, modify the theoretical elasticity solution, and presents nonlinear soil deformation mechanism under the circular foundation with six degrees of freedom.展开更多
The main objective of this study is to investigate the buckling analysis of CCSs reinforced by CNTs subjected to combined loading of hydrostatic pressure and axial compression resting on the twoparameter elastic found...The main objective of this study is to investigate the buckling analysis of CCSs reinforced by CNTs subjected to combined loading of hydrostatic pressure and axial compression resting on the twoparameter elastic foundation(T-P-EF).It is one of the first attempts to derive the governing equations of the CCSs reinforced with CNTs,based on a generalized first-order shear deformation shell theory(FSDST)which includes shell-foundation interaction.By adopting the extended mixing rule,the effective material properties of CCSs reinforced by CNTs with linear distributions are approximated by introducing some efficiency parameters.Three carbon nanotube distribution in the matrix,i.e.uniform distribution(U)and V and X-types linear distribution are taken into account.The stability equations are solved by using the Galerkin procedure to determine the combined buckling loads(CBLs)of the structure selected here.The numerical illustrations cover CBLs characteristics of CCSs reinforced by CNTs in the presence of the T-P-EF.Finally,a parametric study is carried out to study the influences of the foundation parameters,the volume fraction of carbon nanotubes and the types of reinforcement on the CBLs.展开更多
Different criteria and factors are used in different methods of soft soil foundation settlement calculation and engineering geological zoning.The methods used are not universally suitable for complex geological enviro...Different criteria and factors are used in different methods of soft soil foundation settlement calculation and engineering geological zoning.The methods used are not universally suitable for complex geological environments.The post-construction settlement of soft soil foundations are especially large and difficult to calculate.In addition,there are many deficiencies in the current methods used for engineering geological zoning.Focusing on the need of establishing engineering geological zoning for areas with soft soil foundations in the Tianjin Marine Economic Area,combination weighting and extension methods were introduced.An evaluation model for the settlement of soft soil foundations was established using multiple factors and large amounts of data.This evaluation model is accurate and objective for delineating engineering geological zoning.These methods eliminate deficiencies by considering both objective and subjective factors,and help obtain an objective and accurate result.展开更多
The lateral response of combined pile-raft foundations(CPRFs)adjacent to tunnel excavation is a challenging problem owing to the complexity of the pile-raft connections.In current engineering practices,the impact of t...The lateral response of combined pile-raft foundations(CPRFs)adjacent to tunnel excavation is a challenging problem owing to the complexity of the pile-raft connections.In current engineering practices,the impact of these connections on the lateral performance of CPRFs is frequently overlooked,despite their importance.To address this issue,this study conducted three-dimensional finite element analyses to evaluate the contribution of pile-raft connections to the tunnelling-induced lateral performance of CPRFs in saturated clay.In the analysis,both passive and active loading at the pile head could be considered by varying the tunnel depth.Several parameter studies,such as relative pile-raft modulus,pile embedded modulus,pile embedded depths,and pile shaft skin friction,were conducted to determine the optimal design parameters for CPRFs.The results indicate that pile-raft connections significantly affect the tunnellinginduced deflections and bending moments of pile groups.Inspired by the results,a simplified design method,the pile-raft connection coefficient Kc was proposed.Additionally,the pile-head restraint percentage was established to make a relationship with the pile-raft connection coefficient in order to assess the pile-raft connection and guide the pile-raft design.In this paper,the recommended range value of Kc is 10–200 and the range value of pile-head restraint percentage is 24%–42%.展开更多
Pile foundation bearing-retaining wall combination structure is a new type of support structure developed in recent years.This article focuses on the characteristics,advantages,and application scope of the support str...Pile foundation bearing-retaining wall combination structure is a new type of support structure developed in recent years.This article focuses on the characteristics,advantages,and application scope of the support structure,while combining a variety of algorithms,according to different geological conditions and slope stability,as well as summarizes the pile foundation bearing-retaining wall combination structure force analysis and design methods,taking a high-fill road project in Chongqing as an example.The application of this support structure under special conditions,such as thicker soil layer,steeper sliding surface,weak foundation,and limited slope release conditions,is presented,which illustrates the technical advantages of this support structure and proving that it has several other advantages,including clear force mechanism as well as economic and reasonable structure,thus providing reference for similar projects.展开更多
Based on the idea of optimization design of pile type, the two kinds of the typical pile type are selected, which containing flexibility pile (e.g. rammed cement-soil pile is for short RCSP), and rigid pile (e.g. ceme...Based on the idea of optimization design of pile type, the two kinds of the typical pile type are selected, which containing flexibility pile (e.g. rammed cement-soil pile is for short RCSP), and rigid pile (e.g. cement-flyash-gravel pile is for short CFGP). The three kinds of the composite foundation are designed, which are CFGP, CFG long pile and CFG short pile (for short CFGLP-CFGSP), CFG long-short pile and rammed cement-soil short pile (for short CFGLP-RCSSP). Natural earthquake is simulated by using the engineering blasting;the dynamic characteristics and dynamic response of the composite foundation are studied through field test. CFGLP-RCSSP is closed to linear relation. The bearing capacity of the four composite foundation of the CFGP, CFGLP-CFGSP, and CFGLP-RCSSP in the site are 225 kPa, 179 kPa, and 197 kPa, separately increases 150%, 98.8% and 119% compared to the natural foundation. The vibration main frequency is mainly depended on properties of foundation soil and piles between vibration source and measuring point, pilling load value. Horizontal vibration main frequency greater than the vertical vibration main frequency and the vertical vibration main frequency close to the first-order natural frequency of composite foundation. With the pilling load increasing, the CFGLP-RCSSP pile composite foundation combined frequency decreased. Under the same blast energy, the acceleration peak on the CFG pile composite foundation is less than CFGLP-CFGSP the corresponding values, as the load increases, the peak acceleration gently. CFG pile composite foundation is favorable on seismic. The distribution of peak acceleration is consistent within 4 m from pile top in the CFGLP_RCSSP composite foundation. The maximum of the horizontal acceleration peak along the pile body occurs at a distance of pile top 4 m or the pile top, and that of vertical acceleration peak occurred at a pile top.展开更多
基金The financial support for this study is through the grants 50909050 from the National Natural Science Foundation of ChinaZR2009FQ004 from the Natural Science Foundation of Shandong Province
文摘The foundations of some ocean engineering structures are built to withstand not only the vertical gravity load V, but also the horizontal load H induced by sea waves and current. The horizontal load includes the concentrated force load, the moment load M, and the torque load T termed also as combined loading. It is of academic and engineering significance to study the deformation law of submarine seabed due to combined loading. On the basis of the three-dimensional elastic mechanics solution of circular foundation, numerical methods are used to analyze the deformation law of submarine soil under circular foundation with six degrees of freedom. The finite element analysis results give the elastic deformation law of soil in three dimensional spaces, modify the theoretical elasticity solution, and presents nonlinear soil deformation mechanism under the circular foundation with six degrees of freedom.
文摘The main objective of this study is to investigate the buckling analysis of CCSs reinforced by CNTs subjected to combined loading of hydrostatic pressure and axial compression resting on the twoparameter elastic foundation(T-P-EF).It is one of the first attempts to derive the governing equations of the CCSs reinforced with CNTs,based on a generalized first-order shear deformation shell theory(FSDST)which includes shell-foundation interaction.By adopting the extended mixing rule,the effective material properties of CCSs reinforced by CNTs with linear distributions are approximated by introducing some efficiency parameters.Three carbon nanotube distribution in the matrix,i.e.uniform distribution(U)and V and X-types linear distribution are taken into account.The stability equations are solved by using the Galerkin procedure to determine the combined buckling loads(CBLs)of the structure selected here.The numerical illustrations cover CBLs characteristics of CCSs reinforced by CNTs in the presence of the T-P-EF.Finally,a parametric study is carried out to study the influences of the foundation parameters,the volume fraction of carbon nanotubes and the types of reinforcement on the CBLs.
基金National Natural Science Foundations of China(Nos.41172236,41402243)
文摘Different criteria and factors are used in different methods of soft soil foundation settlement calculation and engineering geological zoning.The methods used are not universally suitable for complex geological environments.The post-construction settlement of soft soil foundations are especially large and difficult to calculate.In addition,there are many deficiencies in the current methods used for engineering geological zoning.Focusing on the need of establishing engineering geological zoning for areas with soft soil foundations in the Tianjin Marine Economic Area,combination weighting and extension methods were introduced.An evaluation model for the settlement of soft soil foundations was established using multiple factors and large amounts of data.This evaluation model is accurate and objective for delineating engineering geological zoning.These methods eliminate deficiencies by considering both objective and subjective factors,and help obtain an objective and accurate result.
基金funded by the National Natural Science Foundation of China(Grant No.51878157,52308341)the Natural Science Foundation of Jiangsu Province(Grant No.BK20181282)the China Scholarship Council(CSC202106090083).
文摘The lateral response of combined pile-raft foundations(CPRFs)adjacent to tunnel excavation is a challenging problem owing to the complexity of the pile-raft connections.In current engineering practices,the impact of these connections on the lateral performance of CPRFs is frequently overlooked,despite their importance.To address this issue,this study conducted three-dimensional finite element analyses to evaluate the contribution of pile-raft connections to the tunnelling-induced lateral performance of CPRFs in saturated clay.In the analysis,both passive and active loading at the pile head could be considered by varying the tunnel depth.Several parameter studies,such as relative pile-raft modulus,pile embedded modulus,pile embedded depths,and pile shaft skin friction,were conducted to determine the optimal design parameters for CPRFs.The results indicate that pile-raft connections significantly affect the tunnellinginduced deflections and bending moments of pile groups.Inspired by the results,a simplified design method,the pile-raft connection coefficient Kc was proposed.Additionally,the pile-head restraint percentage was established to make a relationship with the pile-raft connection coefficient in order to assess the pile-raft connection and guide the pile-raft design.In this paper,the recommended range value of Kc is 10–200 and the range value of pile-head restraint percentage is 24%–42%.
基金Youth Project of Science and Technology Research of Chongqing Municipal Education Commission“Research on the Promotion of Pile Foundation Bearing-Retaining Wall Combined Structure Technology”(Project Number:KJQN201905601)Youth Project of Science and Technology Research of Chongqing Education Commission“Research on Construction Monitoring and Risk Warning of Deep Foundation Pit Project Based on BIM+Internet of Things”(Project Number:KJQN201904306)。
文摘Pile foundation bearing-retaining wall combination structure is a new type of support structure developed in recent years.This article focuses on the characteristics,advantages,and application scope of the support structure,while combining a variety of algorithms,according to different geological conditions and slope stability,as well as summarizes the pile foundation bearing-retaining wall combination structure force analysis and design methods,taking a high-fill road project in Chongqing as an example.The application of this support structure under special conditions,such as thicker soil layer,steeper sliding surface,weak foundation,and limited slope release conditions,is presented,which illustrates the technical advantages of this support structure and proving that it has several other advantages,including clear force mechanism as well as economic and reasonable structure,thus providing reference for similar projects.
文摘Based on the idea of optimization design of pile type, the two kinds of the typical pile type are selected, which containing flexibility pile (e.g. rammed cement-soil pile is for short RCSP), and rigid pile (e.g. cement-flyash-gravel pile is for short CFGP). The three kinds of the composite foundation are designed, which are CFGP, CFG long pile and CFG short pile (for short CFGLP-CFGSP), CFG long-short pile and rammed cement-soil short pile (for short CFGLP-RCSSP). Natural earthquake is simulated by using the engineering blasting;the dynamic characteristics and dynamic response of the composite foundation are studied through field test. CFGLP-RCSSP is closed to linear relation. The bearing capacity of the four composite foundation of the CFGP, CFGLP-CFGSP, and CFGLP-RCSSP in the site are 225 kPa, 179 kPa, and 197 kPa, separately increases 150%, 98.8% and 119% compared to the natural foundation. The vibration main frequency is mainly depended on properties of foundation soil and piles between vibration source and measuring point, pilling load value. Horizontal vibration main frequency greater than the vertical vibration main frequency and the vertical vibration main frequency close to the first-order natural frequency of composite foundation. With the pilling load increasing, the CFGLP-RCSSP pile composite foundation combined frequency decreased. Under the same blast energy, the acceleration peak on the CFG pile composite foundation is less than CFGLP-CFGSP the corresponding values, as the load increases, the peak acceleration gently. CFG pile composite foundation is favorable on seismic. The distribution of peak acceleration is consistent within 4 m from pile top in the CFGLP_RCSSP composite foundation. The maximum of the horizontal acceleration peak along the pile body occurs at a distance of pile top 4 m or the pile top, and that of vertical acceleration peak occurred at a pile top.
