| There are many mountains,rivers and lakes in China,the geological situation is complex and changeable,and the soft soil geology is widely distributed.With the development of national economy,infrastructure such as roads,railways,bridges and so on are being built continuously,and the accidents of subgrade instability are frequent,while the uneven settlement and damage of subgrade in deep soft soil area often take the lead in the toe of embankment slope.In this paper,the engineering characteristics of inclined straight pile in homogeneous sand at the foot of embankment slope are studied by model test in laboratory.The experimental results show that:(1)In the process of three times of loading,the horizontal displacement of inclined vertical pile increases with the increase of load,and the growth rate increases first and then decreases.Under the same load condition,the horizontal displacement of the inclined and straight pile decreases with the increase of the combined spacing,and there is the maximum horizontal displacement at the top of the pile,and the difference between the horizontal displacement of the top and the bottom of the pile decreases with the increase of the spacing,thus forming the failure mode that the small-spacing inclined and straight pile is prone to"translation+rotation around the bottom of the pile".In the process of loading,the horizontal displacement increases with the increase of load.Under the same load condition,The horizontal displacement of the coupling beam decreases with the increase of the row spacing,and the most obvious decrease is between 2.5D and 4D.(2)In the process of three times of loading,the lateral earth pressure of each pile body increases with the increase of load,and there is a peak earth pressure at one place of the pile body of the straight pile,while the peak earth pressure of the inclined pile appears at the bottom of the pile.Under the same load condition,The lateral earth pressure of inclined straight pile is affected by row spacing.Within 1D～5.5d,the earth pressure of straight pile and inclined pile increases with row spacing.(3)During the loading process,the bending moment of the inclined-straight pile increases with the increase of load,and the peak bending moment appears at 1/2L of the pile body,while the peak bending moment of the inclined pile body appears at the pile head.In the unloading process,the bending moment of straight pile and inclined pile decreases with the decrease of load value,but it will eventually maintain a certain value.Under the same load conditions,Within 1D～5.5d,the bending moment of straight pile increases with the increase of row spacing,and the peak bending moment of inclined pile increases with the increase of row spacing.(4)In the inclined-straight composite pile,the axial force at each point of the straight pile and the inclined pile increases with the increase of load.The peak axial force at 1/2L of the pile body exists in the straight pile,and the inclined street pile changes from negative axial force to positive axial force under the action of load.Under the same load conditions,the abrupt change of the axial force of each straight pile is related to the spacing,and the larger the spacing is,the easier the abrupt change;the boundary load corresponding to the axial force of inclined pile decreases with the increase of the spacing.By analyzing the law of horizontal displacement of pile body and the characteristics of internal force of pile body,comprehensively considering the lateral displacement resistance and bending resistance of inclined-straight piles,the inclined straight pile at the foot of embankment slope should reduce the row distance as much as possible,but the horizontal displacement should be controlled. |
