Research and Application on Pore-forming Technology of Pile Foundation in Fractured Zone and Hard Rock Complex Stratum
The fracture zone-hard rock stratum has the characteristics of poor stability of rock and soil in the fracture zone and high strength of the hard rock stratum.To solve the hole-forming problem of pile foundation in complex strata of fracture zone-hard rock,this paper proposes a layered hole-forming technology of rotary drilling and down-the-hole hammer drilling,which combines the powerful crushing ability of the down-the-hole(DTH)hammer and introduces the rotary drilling follow-up casing to penetrate the broken rock strata,giving full play to the advantages of their respective processes.Taking the large-diameter foundation pile project at the southern foot of the Xishan Mountain in Beijing as an example,this paper expounds on important construction parameters such as air volume and air pressure of the air compressor,mechanical configuration of the DTH hammer,drilling procedure and drilling efficiency,summarizes and analyzes the common problems and causes in the process of DTH hammer drilling,and puts forward corresponding treatment methods.The layered hole-forming technology of the rotary drilling-DTH hammer effectively improves the drilling efficiency and hole-forming quality,and provides a certain theoretical basis and practical experience for the pile foundation hole-forming technology in complex rock strata.
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