孔桩施工概论（Introduction of bored pile construction）.doc

孔桩施工概论（Introduction of bored pile construction） Since 1980s, bored piles have been widely used in coastal areas such as high-rise buildings, roads, bridges and other foundations, and the applicable foundation forms are more and more widely. With the continuous expansion of the scale of the building, also continue to improve the bearing requirements of pile foundation, the traditional approach is to expand the diameter of pile, pile into the bedrock, but in some very thick sand layer, bedrock deep area according to the traditional method is no longer suitable, economic, and grouting method is an economic this paper discusses the method of using post grouting method to improve the pile into the sand of the bored pile vertical bearing capacity of the application. The main reason affecting the vertical bearing capacity of Bored Piles Due to the existing construction technology, the disturbance of bored pile in the hole in the hole wall of soil, and the pile after pile bottom sediment is thick and mudcake thickness and other factors, seriously affect the vertical bearing capacity of bored pile. Whether it is a positive cycle or reverse cycle construction of the pile, or the positive cycle or reverse circulation, clear hole pile, there are varying degrees of the above problems. Such as an office building project, with the diameter of 800 ~ 1400mm in diameter bored pile, obtained by static load test experiment of single pile vertical bearing capacity (determined by settlement) was 4250kn, the minimum is only 2500kN, the maximum value is 1.7 times the minimum value, the dynamic test of pile quality detection, found the piles are good, no broken pile, necking, segregation and other undesirable phenomena, the length of pile can meet the design requirements. The bearing capacity of pile bearing capacity and bearing capacity including the soil to the pile structure itself, so that the bearing capacity of the pile body is not obviously low structural strength caused by pile foun