Study on Construction of Cast-in-place Pile in Soft Soil and Sandy Soil by Rotary Extrusion Drilling Method
Research purposes:The conventional rotary drilling method in the ground water-rich clay stratum and soft soil and sandy soil stratum is used to construct cast-in-place piles,and some cast-in-place piles are enlarged and shrunk because of hole collapse,which wastes concrete and makes cast-in-place piles unqualified.This paper puts forward to improve the rotary drilling method to the rotary extrusion drilling method,so as to achieve the complete qualified pile with slight enlarging diameter and no reducing diameter and no wasting of concrete.Research conclusions:(1)It is feasible to improve the slow speed heavy drilling of the rotary drilling bucket into the quick light drilling of the rotary extruding drilling bucket to reduce the vibration and squeeze the soil of the hole wall to prevent the hole wall from collapsing.(2)The long casing wall is used to protect the shallow ground from collapse,and the length of the casing is greater than the thickness of the formation from collapse,for easy-to-collapse and difficult-to-collapse formation,mud wall protection with specific gravity of 1.25 and 1.15,and mud wall protection is the combination of vertical controllable mud and centrifugal horizontal disturbed soil mixed mud,the partially disturbed soil and mud are forced to stick and swirl into the hole wall,and the hole wall is strengthened and stabilized without collapsing.(3)The filling coefficient of cast-in-place concrete is 1.02～1.03 and 1.04～1.05 in the construction of cast-in-place pile in clay stratum,soft soil stratum and sand stratum with rich groundwater by rotary extrusion drilling method,all of the piles can be slightly enlarged without reducing the diameter without wasting the whole qualified concrete pile,and the hole-forming efficiency is high,the pollution is reduced,and the cost is saved.(4)The research results can provide reference for improving the construction quality of concrete cast-in-place pile in the fields of railway and highway.
NETL
NSTL
万方数据
