Deep foundation pit excavation is a basic and key step involved in modern building construction.In order to ensure the construction quality and safety of deep foundation pits,this paper takes a project as an example t...Deep foundation pit excavation is a basic and key step involved in modern building construction.In order to ensure the construction quality and safety of deep foundation pits,this paper takes a project as an example to analyze deep foundation pit excavation technology,including the nature of this construction project,the main technical measures in the construction of deep foundation pit,and the analysis of the safety risk prevention and control measures.The purpose of this analysis is to provide scientific reference for the construction quality and safety of deep foundation pits.展开更多
Foundation pit excavation engineering is an old subject full of decision making. Yet, it still deserves further research due to the associated high failure cost and the complexity of the geological conditions and/or t...Foundation pit excavation engineering is an old subject full of decision making. Yet, it still deserves further research due to the associated high failure cost and the complexity of the geological conditions and/or the surrounding existing infrastructure around it. This article overviews the risk control practice of foundation pit excavation projects in close proximity to <span style="font-family:Verdana;">existing</span><span style="font-family:Verdana;"> disconnected piled raft. More focus is given to geotechnical aspects. The review begins with achievements to ensure excavation performance </span><span style="font-family:Verdana;">requirements,</span><span style="font-family:Verdana;"> and follows to discuss the complex </span><span style="font-family:Verdana;">soil structure</span><span style="font-family:Verdana;"> interaction involved among the fundamental components</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">: </span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">the retaining wall, mat, piles, cushion, and the soil. After bringing consensus points to practicing engineers and </span><span style="font-family:Verdana;">decision makers</span><span style="font-family:Verdana;">, it then suggests possible future research directions.</span></span></span></span>展开更多
The excavation of a foundation pit considerably affects the adjacent structures and underground pipelines owing to the change in the stress state of the surrounding soil,resulting in deformation.The study of an actual...The excavation of a foundation pit considerably affects the adjacent structures and underground pipelines owing to the change in the stress state of the surrounding soil,resulting in deformation.The study of an actual engineering case was conducted to examine the influence of excavation on the deformation of adjacent subway tunnels.The finite element analysis software PLAXIS 3D was used to simulate the entire excavation process.The structural design of the foundation pit was optimized based on the simulation results to ensure the stability of the foundation pit and the safety of the existing subway tunnel structure.Finally,the safety evaluation of the excavation of the foundation pit that caused the deformation of the adjacent subway tunnel was performed.The influence of the excavation and unloading of the foundation pit on the subway tunnel is closely related to the distance between the subway and the foundation pit,the amount of earthwork excavated at one time,and the engineering geological conditions.The results of this paper can provide useful reference for the design optimization and safety assessment of similar projects.展开更多
Many uncertain factors in the excavation process may lead to excessive lateral displacement or overlimited internal force of the piles,as well as inordinate settlement of soil surrounding the existing bridge foundatio...Many uncertain factors in the excavation process may lead to excessive lateral displacement or overlimited internal force of the piles,as well as inordinate settlement of soil surrounding the existing bridge foundation.Safety control is pivotal to ensuring the safety of adjacent structures.In this paper,an innovative method is proposed that combines an analytic hierarchy process(AHP)with a finite element method(FEM)to reveal the potential impact risk of uncertain factors on the surrounding environment.The AHP was adopted to determine key influencing factors based on the weight of each influencing factor.The FEM was used to quantify the impact of the key influencing factors on the surrounding environment.In terms of the AHP,the index system of uncertain factors was established based on an engineering investigation.A matrix comparing the lower index layer to the upper index layer,and the weight of each influencing factor,were calculated.It was found that the excavation depth and the distance between the foundation pit and the bridge foundation were fundamental factors.For the FEM,the FE baseline model was calibrated based on the case of no bridge surrounding the foundation pit.The consistency between the monitoring data and the numerical simulation data for a ground settlement was analyzed.FE simulations were then conducted to quantitatively analyze the degree of influence of the key influencing factors on the bridge foundation.Furthermore,the lateral displacement of the bridge pile foundation,the internal force of the piles,and the settlement of the soil surrounding the pile foundation were emphatically analyzed.The most hazardous construction condition was also determined.Finally,two safety control measures for increasing the numbers of support levels and the rooted depths of the enclosure structure were suggested.A novel method for combining AHP with FEM can be used to determine the key influencing aspects among many uncertain factors during a construction,which can provide some beneficial references for engineering design and construction.展开更多
文摘Deep foundation pit excavation is a basic and key step involved in modern building construction.In order to ensure the construction quality and safety of deep foundation pits,this paper takes a project as an example to analyze deep foundation pit excavation technology,including the nature of this construction project,the main technical measures in the construction of deep foundation pit,and the analysis of the safety risk prevention and control measures.The purpose of this analysis is to provide scientific reference for the construction quality and safety of deep foundation pits.
文摘Foundation pit excavation engineering is an old subject full of decision making. Yet, it still deserves further research due to the associated high failure cost and the complexity of the geological conditions and/or the surrounding existing infrastructure around it. This article overviews the risk control practice of foundation pit excavation projects in close proximity to <span style="font-family:Verdana;">existing</span><span style="font-family:Verdana;"> disconnected piled raft. More focus is given to geotechnical aspects. The review begins with achievements to ensure excavation performance </span><span style="font-family:Verdana;">requirements,</span><span style="font-family:Verdana;"> and follows to discuss the complex </span><span style="font-family:Verdana;">soil structure</span><span style="font-family:Verdana;"> interaction involved among the fundamental components</span><span style="font-family:Verdana;"><span style="font-family:Verdana;"><span style="font-family:Verdana;">: </span></span></span><span><span><span style="font-family:;" "=""><span style="font-family:Verdana;">the retaining wall, mat, piles, cushion, and the soil. After bringing consensus points to practicing engineers and </span><span style="font-family:Verdana;">decision makers</span><span style="font-family:Verdana;">, it then suggests possible future research directions.</span></span></span></span>
基金the National Natural Science Foundation Project of China(grant number:51768040 and 51508256).
文摘The excavation of a foundation pit considerably affects the adjacent structures and underground pipelines owing to the change in the stress state of the surrounding soil,resulting in deformation.The study of an actual engineering case was conducted to examine the influence of excavation on the deformation of adjacent subway tunnels.The finite element analysis software PLAXIS 3D was used to simulate the entire excavation process.The structural design of the foundation pit was optimized based on the simulation results to ensure the stability of the foundation pit and the safety of the existing subway tunnel structure.Finally,the safety evaluation of the excavation of the foundation pit that caused the deformation of the adjacent subway tunnel was performed.The influence of the excavation and unloading of the foundation pit on the subway tunnel is closely related to the distance between the subway and the foundation pit,the amount of earthwork excavated at one time,and the engineering geological conditions.The results of this paper can provide useful reference for the design optimization and safety assessment of similar projects.
基金The authors acknowledge the National Key Research and Development Program of China(No.2017YFC0805402)the Open Project of the State Key Laboratory of Disaster Reduction in Civil Engineering(No.SLDRCE17-01)+1 种基金the Incentive Fund for Overseas Visits of Doctoral Students of Tianjin University in 2019(070-0903077101)the China Scholarship Council(CSC,201906250153)for their financial support.
文摘Many uncertain factors in the excavation process may lead to excessive lateral displacement or overlimited internal force of the piles,as well as inordinate settlement of soil surrounding the existing bridge foundation.Safety control is pivotal to ensuring the safety of adjacent structures.In this paper,an innovative method is proposed that combines an analytic hierarchy process(AHP)with a finite element method(FEM)to reveal the potential impact risk of uncertain factors on the surrounding environment.The AHP was adopted to determine key influencing factors based on the weight of each influencing factor.The FEM was used to quantify the impact of the key influencing factors on the surrounding environment.In terms of the AHP,the index system of uncertain factors was established based on an engineering investigation.A matrix comparing the lower index layer to the upper index layer,and the weight of each influencing factor,were calculated.It was found that the excavation depth and the distance between the foundation pit and the bridge foundation were fundamental factors.For the FEM,the FE baseline model was calibrated based on the case of no bridge surrounding the foundation pit.The consistency between the monitoring data and the numerical simulation data for a ground settlement was analyzed.FE simulations were then conducted to quantitatively analyze the degree of influence of the key influencing factors on the bridge foundation.Furthermore,the lateral displacement of the bridge pile foundation,the internal force of the piles,and the settlement of the soil surrounding the pile foundation were emphatically analyzed.The most hazardous construction condition was also determined.Finally,two safety control measures for increasing the numbers of support levels and the rooted depths of the enclosure structure were suggested.A novel method for combining AHP with FEM can be used to determine the key influencing aspects among many uncertain factors during a construction,which can provide some beneficial references for engineering design and construction.