砂土地层悬臂倾斜长短桩支护性能模型试验研究

倾斜桩能够提高排桩水平承载力，而长短桩依据桩身弯矩分布减小部分支护桩的桩长，以充分利用支护桩承载力，将两者结合可形成倾斜长短桩。为研究倾斜长短桩作为基坑围护结构时的变形受力特性，通过常规室内砂土模型试验，分析倾斜长桩倾斜角度和长短桩配比的影响。试验结果显示： 1）对比等长长桩，倾斜长短桩能够在减小总桩长时，更有效地控制支护结构变形和桩身弯矩； 2）对于倾斜长短桩而言，在倾斜桩倾斜角度为0°～20°时，其支护效果随着倾斜角度增大而提高； 3）倾斜长短桩的桩身弯矩会随着倾斜角度增大而减小，且开挖面以下弯矩减小幅度更大； 4）倾斜长短桩中，长桩与短桩在开挖面以上弯矩相近，开挖面以下长桩弯矩显著大于短桩弯矩； 5）短桩占比越大，支护效果越弱，桩身弯矩越大。

Cantilevered Inclined Long Short Piles Support PerformanceModel for Sandy Soil Strata

Inclined piles can improve the horizontal bearing capacity of row piles. The long short piles can reduce the pile length of part of the supporting pile according to the pile moment distribution and to completely use the supporting pile bearing capacity. The combination of these two forms the inclined long short piles. To study the deformation force characteristics of inclined long short combined piles as foundation pit retaining structures, the influence of inclined long pile inclination angle and long and short piles ratio are analyzed using conventional indoor sand model test. The test results show the following: (1) Compared with long piles with equivalent lengths, the inclined long short piles can effectively control the deformation and pile moment when the total pile length is reduced. (2) When the inclined pile inclination angle ranges from 0° to 20°, the support effect increases with an increase in inclination angle. (3) The pile moment of the inclined long short piles decreases with an increase in inclination angle, and the decrease of moment below the excavation surface is much greater. (4) The bending moment of long short piles above the excavation surface is similar, and that below the excavation surface of long piles is considerably larger than that of short piles. (5) The higher the proportion of short piles, the weaker is the support effect and the larger is the bending moment of piles.