Study On Bearing Performance Of Carrier Pile In Medium-dense Silty Soil Bearing Layer

Carrier pile as an emerging pile type,its design and construction involves building structure,dynamics,materials science and other disciplines.Compared with ordinary pouring piles and expanded bottom-type pouring piles,carrier piles have the advantages of fast construction speed,good pile quality,high bearing capacity and good seismic performance,and have broad application prospects.At present,the research and application of this technology in the silt layer is still relatively small,so this paper mainly studies the bearing performance and application effect of carrier piles in the bearing layer of medium-dense silty soil,providing a reference for the future application of carrier piles in similar geology.Taking an engineering project in Zhengzhou city as the background,this paper studies the bearing capacity of carrier pile in the medium-dense silt soil layer by means of theoretical analysis,field test and finite element analysis.The main contents and research results are as follows:(1)By analyzing the bearing mechanism of the carrier pile,the law of load transmission and the mechanism of action of the expansion head,it is concluded that the force of the carrier pile is equivalent to the multi-level expansion foundation,and the failure mode of the single pile of the carrier pile is mainly punching and shearing failure.(2)The pile integrity of the carrier pile test pile was examined by low-strain dynamic testing method,and the pile formation quality of the carrier pile in the bearing layer of medium-dense silt soil was analyzed.The load-settlement curve obtained from the static load test is slowly variable,and the damage characteristics of the pile and soil are not obvious,which indicates that the carrier pile presents the characteristics of endbearing pile.(3)The two-dimensional models of ordinary grouted piles and expanded bottom grouted piles were established using finite element software,and the differences in stress and settlement between them and carrier piles were compared,reflecting the bearing advantages of carrier piles over ordinary grouted piles and expanded bottom grouted piles in the bearing layer of medium-dense silt soil.(4)The distribution rules of pile shaft force,pile side frictional resistance and pile end total resistance of carrier pile under vertical load were analyzed.Different models of pile diameter,pile length and carrier diameter were established to analyze the main factors affecting the vertical bearing capacity of carrier pile.The simulation results show that the vertical bearing capacity of carrier pile is mainly affected by the size of carrier and soil properties of bearing layer.(5)The change law of horizontal displacement of the pile body along the burial depth and the deformation of the soil around the pile under the action of horizontal load were analyzed.Different models of pile diameter and carrier diameter were established to analyze the main factors affecting the horizontal bearing capacity of carrier pile,and the simulation results show that the horizontal bearing capacity of carrier pile can be improved by increasing the pile diameter.