Laboratory Model Experimental Study On Static Bearing Capacity Of Screw Pile

Screw pile is a kind of special-shaped pile foundation with thread.The existence of thread makes it has good bearing capacity.In this paper,the effect of pitch and density of soil on the load-carrying properties of screw pile is studied through laboratory model test,and the optimal pitch of screw pile is analyzed by combining the lateral resistance of model pile and engineering material cost.(1)Through the static load test of screw pile with different pitch,the influence of pitch on the load-settlement relationship,bearing capacity composition and lateral resistance distribution characteristics of screw pile is analyzed.The results show that screw pile belongs to friction pile,and the bearing capacity and settlement control ability of screw pile are better than that of ordinary pile;The lateral resistance distribution of the screw pile is different from the ordinary pile.It is more concentrated at the upper part of the screw pile,while the lower part is sparse.In practical application,the pile length should be rationally selected.(2)Through the static load test of screw pile in soil with different compactness,the influence of soil compactness on the bearing characteristics of screw pile is analyzed.The results show that the curves of load-settlement of the screw pile in the soil with different compactness are slowly varying.By the improvement of engineering measures,the compactness of soil can improve the bearing capacity and settlement control ability of the screw pile,but it is not appropriate in the soil with higher compactness.With the increase of soil compactness,the proportion of lateral resistance of screw pile increases gradually.High compactness had caused the failure modes of screw pile is similar to brittle failure.When the pile top load exceeds the ultimate lateral resistance,will reduce the lateral resistance of piles.(3)Based on the model test results,the Analyses on the pitch optimization of screw pile were conducted.The analysis shows that both axial force method and s-lgQ curve method can be used to determine the ultimate lateral resistance.When reaches the ultimate load,the lateral resistance weakening effect of screw pile is lower than ordinary pile.Due to limiting lateral resistance,the optimal pitch diameter ratio of the model pile is 1.361.When the pitch diameter ratio is between 1.20 and 2.03,the screw pile can keep a higher lateral resistance enhancement coefficient.In order to control the materials costs,the optimal pitch diameter ratio of model pile is 2.0,and the economical efficiency of screw pile can reach 6.68 times than ordinary pile.When the pitch diameter ratio is between 1.5 and 2.5,the economical efficiency of screw pile is in optimal rangeFigure 32 Table 7 Reference 75...