Research On Quality Of Drilled Holes For Cast-in-Place Piles In Shanghai District

Analyzing many civil engineering accidents and some useful experience, based on initial site recordings, this dissertation describes main factors which significantly affect construction quality of cast-in-place piles in Shanghai district.The differences of drilled holes' character, brought up by using different construction equipments are very obvious, a proper choice can improve the bearing capacity of piles.Summarizing diameter changing rules of drilled holes in different ground, as well as that at different time after the holes being drilled. Estimating the changing range of diameter.Analyzing some attentions while using mud to maintain the stability of drilled holes. With physics and mechanics method to compare and contrast, mud film is deeply studied, as a consequence, the material components and characters are detailed recounted.Introducing the measure of coarseness, and the computation formula. Pointing out some details, which should be paid special attention. The relations between coarseness and pile quality are also concluded.The stability of drilled holes is analyzed with elastic theory, compared the differences between method of considering cohesion and that not considering cohesion. Pointed out some rules of stability and the affecting range of drilling holes in ideal conditions.At last, some advice of this research project is given by the author.