Research On Application Of PC Pile As Anchor Pile In Bearing Capacity Test Of Foundation Pile

PC pile has the advantages of high pile strength and adaptability to various geotechnical engineering construction conditions.Widely used in various infrastructural projects.The common testing methods are expensive,unsafe and difficult.Therefore,an anchor pile method of filling grouting material in pile and connecting thread steel bar and beam to form a reaction system is proposed.In order to make the method can be better applied to engineering practice,the bond mechanism between grouting material and the inner wall of finishing rolled thread steel bar and PC pile is studied deeply.Computational analysis based on experimental studies,analyze the influence of various factors on the compressive bearing capacity and uplift bearing capacity of PC pile,the ratio range of compressive bearing capacity and uplift bearing capacity of PC pile in engineering practice is calculated.The main contents and conclusions are as follows:(1)20 groups of 60 fine rolled thread rebar and grouting material bonding test,the influence of six factors,such as thickness of protective layer,diameter of fine rolled thread reinforcement,anchorage length,strength grade of grouting material,transverse coupling and curing age.The results show that the bond strength increases with increasing protective layer thickness,hoop edge length,grout strength grade and age of maintenance;the bond strength decreases with increasing diameter of finish-rolled rebar,anchorage length and hoop spacing;the diameter of steel bar,anchorage length and stirrup spacing increase,and the bond strength decreases;fitting bond strength formula;fitting bond-slip relation;the optimal anchorage length is 19 d.(2)Conduct bond performance test between inner wall of 15 PC piles and grouting material,the influence of PC pile inner diameter,grouting anchorage length,grouting material strength grade,eccentricity distance of internal finishing rolled steel bar and curing age on the bond property of specimens was analyzed.The results show that PC pile has large inner diameter and low bond strength;the anchorage length and the eccentricity distance of the internal fine rolled steel bar increase,and the bond strength changes little;with the increase of grouting material strength grade and curing age,the bond strength increases;fitting bond-slip relation.(3)To analyse the effects of pile strength,soil strength and deformation,mechanical properties of the layer around the pile and the connection between the pile top to the bearing effect on the vertical compressive load capacity and pull-out capacity of PC pile monopile,and to calculate the vertical compressive load capacity and pull-out capacity of the PC pile.The results show that the bearing capacity of PC pile is greatly affected by site construction conditions;the ratio of vertical compressive and pull-out bearing capacity of a single pile is in the range of 1.4 to 1.5.