现场模拟水平分布式滑坡推力的抗滑桩试验研究

Field modeling of laterally distributed landslide thrusts over anti-slide piles

为较真实地揭示全埋式抗滑桩在水平分布式滑坡推力作用下的受力和变形性状,依托福建省浦南(浦城-南平)高速公路金斗山大型滑坡治理的一根工程抗滑桩进行了现场大型推桩试验,利用抗滑桩施工现场自行设计的试验槽,通过5台液压油泵控制5排共计10个千斤顶对该桩分别近似按三角形、矩形、抛物线形施加水平分布荷载,以模拟滑坡推力的可能分布形式,实测了抗滑桩的内力和变形。试验结果表明:对于设置在滑坡体某级平台上的全埋式抗滑桩,为大截面人工挖孔桩施工安全而构筑的桩顶钢筋混凝土挡土护墙和桩身护壁可显著减小桩身最大正弯矩,有利于提高抗滑桩的实际承载力,如能在现行设计中考虑这些积极因素,将使抗滑桩的设计更为科学合理;当作用在抗滑桩上的滑坡推力较小,滑动面较浅时,因不同分布形式的合力作用点位置变化不大,使桩身锚固段弯矩的变化不大,因而在设计计算中对滑坡推力分布形式假定的不同,对结果的影响不大。

In order to truly disclose the behavior of wholly buried anti-slide piles under laterally distributed landslide thrusts,based on a practical anti-slide pile,one of the piles used to stabilize the great landslide,i.e.,Jingdou Mountain landslide at the left side of Pucheng-Nanping highway in Fujian Province,large scale field pushing pile tests are performed by using five hydraulic oil pumps and ten jacks.Using the self-designed test pit in the construction site,the laterally triangular,rectangular and parabolic distribution loads are applied on the pile respectively to simulate the probable distribution forms of landslide thrusts.The internal forces and deformation of the anti-slide pile are measured.The experiment results show that for anti-slide piles installed in a platform of landslide mass,for the sake of construction safety of artificial excavation,the reinforced concrete retaining walls above the top of the pile and protecting wall surrounding the pile hole can remarkably reduce the maximum bending moments of the pile and enhance its bearing capacity.If these positive factors are considered in the current designs,the design of anti-slide piles will be more scientific and reasonable.When the landslide thrusts are small and the slippery surfaces are shallow,the acting points of resultant forces of different load distribution forms change so little that the bending moments of anti-slide piles in archored segments have little variation.Therefore,the calculated results will be greatly affected by the hypothesis of different distribution forms of landslide thrusts.