Research On Pore Diameter Variation Rule Of Cast-in-place Pile

Cast-in-place became the primary pile model of high-rise buildings, because it possess many merits such as can be adapted to diverse stratums, without soil compacting effect and shaking, lack of noise, can provide high bearing capacity with medium cost. The construction of cast-in-place pile, which belonging to concealed work, is carried out under ground or beneath the water table. The pile quality can be influence by many uncertain factors, so the pile quality became the most concerned issue. Pore diameter is measured after pore forming, the pore diameter contains plenty information. The effects of various factors to pile quality can be unscrambled. This dissertation mainly studied on the average pore whole changing rule, mean while the mechanism of different factors how to affect the pile quality is researched. The primary conclusions are as following.The roughness of wall of hole is a significant data, which can reflect the pore hole changing rule .Based on the theory of concave convex factor RF, the calculation method of roughness of wall whole in single stratum is bring forward, herein the pore hole changing rule in different stratums can be exactly described. In Shanghai distract ,when adopting normal-circulation drilling method, the pore diameter drilled by GPS-10 boring machine is larger than that of by GPS-15 boring machine, and is the whole easier to collapse. However GPS-15 boring machine is more stable, the pore hole looks like sawtooth, which contributes a lot to the lateral friction. The wall of hole is lubricous, when adopting reverse circulation drilling method, it's a disadvantage for the present of pile bearing capacity, because the most adopted pile model is friction pile and end-support friction pile in Shanghai. The extensive magnitude of pore diameter decreased with the increasing of drill bit diameter and the extensive magnitude of pile diameter in middle-lower stratums is smaller than that in upper stratums.The normal circulation of slurry process the following characteristics, the increment of slurry gravity and viscosity will lead to the mud slice become thicker and the decrement of average pore diameter average roughness of wall of hole. It's influence to deeper stratums is greater than that to shallow stratums. well consideration should be paide to the decrement of slurry gravity and viscosity when the pore is well cleared and wall of hole is well maintained in construction. The average pore diameter fluctuant decreased with the duration of pore forming and...