微型桩侧向承载特性现场大型模型试验研究

On Site Large⁃scale Model Test Research on Lateral Bearing Characteristics of Micro Piles

微型桩具有布置灵活、高效、环保、可在狭小场地施工的特点,在边坡和滑坡应急抢险加固中得到广泛应用,但因对其侧向承载特性的认识不一致而导致其设计计算理论和方法不完善。本文采用坡顶堆载现场大型模型试验方法,研究了垂直微型桩群的侧向承载特性。结果表明:有顶横梁连接的垂直微型桩群的桩顶水平位移较小且前后桩基本一致,整体受力较好;微型桩所受山侧滑坡推力分布近似为三角形,且三角形顶点在桩顶以下,滑面以下桩前土压力分布近似为倒三角形;前后桩桩身弯矩分布均呈S形,正负弯矩的分界点在滑动面附近;由于顶横梁的连接和传力作用,前后桩最大弯矩绝对值相差2.3%,结构受力较为合理;顶横梁上梁端弯矩最大,山侧端梁底面受拉,河侧端梁顶面受拉,且最大弯矩不到桩身最大弯矩的10%。

Micro piles had the characteristics of flexible layout,high efficiency,environmental protection,and could be constructed in narrow sites,which were widely used in the emergency rescue and reinforcement of slopes and landslides.However,due to inconsistent understanding of their lateral bearing characteristics,the design theory of computation and methods were imperfect.This article adopted a large-scale model test method of slope top loading on-site to study the lateral bearing characteristics of vertical micro pile groups.The results show that the horizontal displacement of the pile top of the vertical micro pile group connected by a top crossbeam is small and the front and rear piles are basically the same,and the overall stress is good.The distribution of landslide thrust on the micro pile is approximately a triangular,and the apex of the triangle is below the pile top.The distribution of soil pressure in front of the pile below the sliding surface is approximately an inverted triangular.The bending moment distribution of the front and rear pile bodies is S-shaped,and the boundary point between positive and negative bending moments is near the sliding surface.Due to the connection and force transmission of the top crossbeam,the absolute difference in the maximum bending moment between the front and rear piles is 2.3%,and the structural force is reasonable.The bending moment of the top beam is the largest,the bottom surface of the end beam on the mountain side is strained,the top surface of the end beam on the river side is strained,and the maximum bending moment is less than 10%of the maximum bending moment of the pile body.