The stability of hole wall is the key factor that restricts the quality of bored pile.The factors affecting the stability of the hole wall are divided into three categories:pile hole design parameters,construction technology and soil properties.Among the pile hole design parameters,the hole diameter and hole depth are the key factors affecting the stability of the hole wall.In the construction process,the relative density of mud,the depth of pile casing and the time of forming holes are the key factors affecting the stability of hole walls.The type of soil,and the physical and mechanical properties of soil are the key factors affecting the stability of the hole wall.Corresponding control measures are proposed for each key factor.In the design parameters of pile hole,suitable drilling tools should be selected to precisely control the aperture and hole depth.In terms of construction technology,it is necessary to select appropriate mud relative density and pile casing depth based on hole wall stability and economy,rationally arrange construction organization,shorten the interval time between hole formation and filling,and strictly control drilling speed and drilling tool pressure.In terms of soil properties,we should pay special attention to the soft soil layer and sandy soil layer,adopt the measures of foundation treatment,deepen the pile casing and increase the relative density of mud,so us to ensure the stability of the hole wall,and provide reference for the design and construction of bored pile.
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