The pile working load depends on the imperfections which may be taken place in pile-soil system, during pile construction, among many other factors. This subject attracted the researcher＇s attention world wide in the...The pile working load depends on the imperfections which may be taken place in pile-soil system, during pile construction, among many other factors. This subject attracted the researcher＇s attention world wide in the last decades. Types of imperfections either geotechnical or structural are documented in literature and well explained. Nevertheless, the influence of these imperfections in pile load calculations is still ambiguous. The work presented herein is devoted to study soil disturbance during construction of piles using continuous flight auger, CFA. The study of soil disturbance due to drilling needs some evidence. The source of this evidence is field observations collected from four different construction sites, which are documented in this paper. The study concluded that the disturbed zone of soil by CFA has a conical shape and extending laterally to a distance equivalent to ten times of the pile diameter around the auger at the cutting bits and has an inclined surface of4：1 （vertical ： horizontal）. Furthermore excess pore water pressure was induced in soil in the vicinity of pile drilling. Due to this excess pore water pressure, 3.5% to 6.5% of piles constructed by CFA showed percolation of water from the top of the piles through fresh concrete. Also, subsidence of fresh concrete in pile hole was recorded in few of the constructed piles. Pile loading tests showed that the percolation of water and/or subsidence of fresh concrete have not appreciable influence on the load-displacement characteristics of the piles. Moreover, percolation of water at pile heads.展开更多
文摘The pile working load depends on the imperfections which may be taken place in pile-soil system, during pile construction, among many other factors. This subject attracted the researcher＇s attention world wide in the last decades. Types of imperfections either geotechnical or structural are documented in literature and well explained. Nevertheless, the influence of these imperfections in pile load calculations is still ambiguous. The work presented herein is devoted to study soil disturbance during construction of piles using continuous flight auger, CFA. The study of soil disturbance due to drilling needs some evidence. The source of this evidence is field observations collected from four different construction sites, which are documented in this paper. The study concluded that the disturbed zone of soil by CFA has a conical shape and extending laterally to a distance equivalent to ten times of the pile diameter around the auger at the cutting bits and has an inclined surface of4：1 （vertical ： horizontal）. Furthermore excess pore water pressure was induced in soil in the vicinity of pile drilling. Due to this excess pore water pressure, 3.5% to 6.5% of piles constructed by CFA showed percolation of water from the top of the piles through fresh concrete. Also, subsidence of fresh concrete in pile hole was recorded in few of the constructed piles. Pile loading tests showed that the percolation of water and/or subsidence of fresh concrete have not appreciable influence on the load-displacement characteristics of the piles. Moreover, percolation of water at pile heads.
