抗滑桩桩后土拱效应的作用机理及发育规律

Mechanism and development law of soil arch effect behind anti-slide piles

为揭示抗滑桩桩后土拱效应的作用机理和发育规律,采用平面应变有限元分析模型,对桩周土应力、变形等变化规律进行研究,解释土拱作用的力学机理。根据荷载-位移曲线特征,将土拱发育分为3个阶段,对不同阶段土体中的变形、应力及塑性区开展情况进行分析,研究土拱的发育规律。结果表明:土拱的形成、发展及破坏与桩后荷载p及桩土间相对位移δ大小有关。在p、δ较小时,土体发生弹性变形,土拱处于孕育形成阶段;随着p、δ增大,桩周土体局部产生塑性应变,土拱效应进一步发展并逐渐发挥作用;当p接近极限值时,土体中塑性区范围扩大,δ急剧增长,至塑性区贯通后,土拱破坏,支挡作用失效,土体发生挤出性破坏。

In order to reveal the mechanism and development law of soil arch effect behind the antislide piles,numerical simulations were carried out based on plane stain FEA models.Soil deformation and stress around piles were investigated to explain the mechanism of soil arch formation.Soil arch development can be divided into three phases according to the characteristic of load-displacement curves.Development law was studied by analysis of soil deformation,stress and plastic zone at different stages.The results shows that the formation,development and destruction of soil arch are correlated to the load（p） acted on piles and relative displacement（δ） between piles and soil.Soil arch is at the stage of gestation when both p and δ are small and soil deformation is elastic.Then local plastic strain comes into being around piles with increment of p and δ.Gradually soil arch takes its step further and brings its anti-sliding role into effect.In succession,plastic zone of soil extends and δ grows rapidly when p is close to its limit value.Finally soil arch fractured,retaining effect fails and destroy pattern of soil extrusion between piles occurs once soil plastic zone become connective.