黄土边坡悬臂式与全埋式单排两桩抗滑桩原位模型试验

In-situ Model Test of a Cantilever and Full-buried Single-row Double-pile Stabilizing System on a Loess Slope

以单排两桩抗滑桩为研究对象,将室内抗滑桩缩尺模型试验方法中的重塑土条件改进为原状土条件,参照岩土体现场直剪试验方法设计了抗滑桩现场模型试验,在高速公路高陡黄土边坡上进行悬臂式、全埋式抗滑桩原位缩尺模型试验,确定2种埋设方式的模型桩与原状黄土体相互作用至极限状态过程中的受力变形规律,探究2种埋设形式的抗滑桩在原状黄土中的受力分配过程,获得2种埋设形式的模型桩各自的破坏模式。试验结果表明:各模型桩在受力过程中均经历了零位移阶段、有效变形阶段和失效阶段,并将3个阶段的分界点分别定义为临界启动荷载和临界阻滑荷载。2种埋置形式的模型桩均属于多点依次断裂破坏,两悬臂式模型桩首次破坏点位于模型桩入土深度约68 cm处,A桩为两桩中的首先破坏桩,两桩的临界启动荷载为32.5 kN,临界阻滑荷载为75.5 kN;两全埋式模型桩首次破坏点位于模型桩入土深度约51 cm处,A桩为两桩中的首先破坏桩,A桩的临界启动荷载为32.5 kN,B桩为22 kN,两桩的临界阻滑荷载为93 kN。在全埋式条件下,两桩在受力过程中均存在明显的相互协调过程,而这一过程在悬臂式条件下并未出现。试验结果为抗滑桩破坏预警及设计计算提供了数据支持。

In this study,with a single-row double-pile stabilizing system used as a test object,"remolded soil" required for an indoor reduced-scale model test of stabilizing piles was transformed into undisturbed soil.An in-situ reduced scale model test,which was designed based on a field direct shear test of rock and soil,was conducted on cantilever and full-buried stabilizing piles on high and steep loess slopes of expressways to analyze the deformation of cantilever and full-buried model piles when they reached their ultimate state due to landslide thrust and interaction of soils around piles.This study investigated the force distribution process of two types of piles in undisturbed loess and determined the failure modes of these piles.Test results indicate that each pile experiences three stages,namely,zero displacement,effective deformation,and failure,during the loading process,and their dividing points are defined as starting and critical loads.Both the cantilever and full-buried piles represent specific types of fracture damage,where the first failure point of the two cantilevered model piles is at a penetration depth of approximately 68 cm.Piles A and B have the same starting load of 32.5 kN,and pile A is the first to fail,with the critical load being 75.5 kN.The first failure point of the two full-buried model piles is at a penetration depth of approximately 51 cm.The starting load of pile A is 32.5 kN,but that of pile B is 22 kN.Pile A is the first to fail,with theoretical loads of both piles being 93 kN.In the full-buried condition,the two piles experience a unique phenomenon of mutual coordination during the loading transfer,which is different from the cantilever condition.The test results provide data to support damage early warning and design of stabilizing piles.