| Small-diameter pile groups in deep soft soil areas are easily inclined by lateral excavation or stacking.The model slot and the bearing device are designed to carry out the indoor model test,and the force characteristics of the inclined pile foundation under the vertical repeated loading and unloading are studied,which provides a basis for the design of the inclined pile group.The results showed that:(1)During the 5 loading process,the settlement and horizontal displacement of the inclined pile top and the cap increase with the increase of the load,and the growth rate increases with the increase of the load.During the first 3 loadings,it increases with the load.And decrease.During the 5 unloading process,the settlement and horizontal displacement of the inclined pile top and the cap of the initial stage of the unloading were not obvious,which was unrecoverable shaping deformation,and the elastic deformation began to occur at the last 1?2 level low load.When the load is unloaded to 0,the elastic deformation is maximized.(2)During the five loading or unloading process,under the same load,the settlement of each pile is related to the inclination of the pile and the spacing of the pile.Due to the constraints of the cap,the settlement difference of each pile top is relatively small.Under the same load,the inclination angle is in the range of 3°?12°,and the horizontal displacement of the pile top increases with the increase of the inclination angle.In the group pile foundation,when the inclination of the pile increases,the horizontal displacement change is more sensitive than the settlement,and the horizontal deformation resistance of the pile body is obviously weakened as the inclination becomes larger.(3)Under the same load,compared with the inclined piles,the settlement of the inclined pile foundation is centered,which is basically equal to the average value of each pile settlement;the horizontal displacement of the inclined pile foundation is centered,which is larger than the 6 degree pile and smaller than the 9 degree pile.(4)During the first loading,the deformation ratio of the inclined pile foundation increases with the increase of the load.During the first unloading,the deformation ratio tends to be stable.When the first three loads are applied to the maximum load,the deformation ratio of the inclined pile foundation is between 7.1 and 7.4.This parameter can be used to quickly predict the horizontal displacement of the inclined pile foundation and assist in analyzing the deformation characteristics of the pile foundation.(5)In the inclined pile foundation,the maximum bending moment of the pile body appears near the pile top,which increases with the increase of the load.For the inclined pile,the maximum bending moment of the pile increases with the increase of the inclination,and is sensitive to the inclination and the load increase.(6)There is a "threshold" based on the inclination of the pile body to the failure mode of the pile body(this test is 3°),which increases with the soil compactness and the bending resistance of the pile.When the inclination is not greater than the threshold,the bending moment of the pile body is small,and the bending failure is not easy to occur;When the inclination is greater than the threshold,the bending moment near the top of the pile is relatively large,and the bending failure is easy to occur,and the pile with larger inclination in the group pile is more susceptible to bending failure.At this time,the vertical bearing capacity of the pile is mainly determined by the bending strength of the pile.(7)The failure of the inclined pile foundation is a gradual process that can be monitored.In the project,the inclination of the pile body should be minimized,and it should be controlled within the threshold to strengthen the bending resistance of the area near the pile top and reduce the settlement and horizontal displacement of the inclined pile foundation and prevent the premature bending failure of the pile body. |
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