类土质高边坡开挖效应的离心模型试验及数值模拟研究

STUDY ON EXCAVATION EFFECT OF HIGH SOIL-LIKE SLOPE BY CENTRIFUGAL MODEL TEST AND NUMERICAL SIMULATION

高边坡在开挖过程中具有明显的开挖效应。采用离心模型试验及快速拉格朗日元数值模拟方法对花岗岩全～强风化而成的类土质高边坡的开挖效应进行研究。离心模型试验采用福建省漳(州)龙(岩)高速公路和溪段一边坡原状土样削制而成;数值模拟中采用程序内置的遍布裂缝模型建模。两种研究结果均显示,各级边坡的开挖会对已开挖坡面及未开挖坡面、坡脚产生明显的附加位移和附加不平衡力,有时,这种附加不平衡力会很大,达到原剩余不平衡力的1倍以上,使本已达到平衡的边坡产生新的失稳,这将影响已施工边坡支护工程的稳定性及边坡整体的稳定性。应在边坡工程设计中充分考虑这种边坡开挖效应,使支挡结构的承载能力可以满足多级边坡开挖形成的附加应力要求。

Centrifugal model tests and numerical simulation are carried out to study the excavation effect of high soil-like slope.The excavation effect is worth being noted when multistage slopes and flats are required.Undisturbed soil mass,which is taken from a completely weathered slope along Zhangzhou—Longyan Expressway in Fujian Province,is adopted in centrifugal model tests.Ubiquitous joints plasticity units are used to establish the slope model in numerical simulation with fast Lagrangian analysis of continua.The modeling processes corresponding to the centrifugal model test and numerical simulation respectively are recommended in detail.The test approaches and measuring instruments are also put forward.The conclusions drawn from above two methods show that the excavation of each slope-stage will bring additive displacement and unbalance force on other slope stages.The additive displacement and unbalance force will threaten the stability of the excavated slope stages,even the whole slope and the supporting engineering.Sometimes the additive unbalance force will be over twice of the originally residual amount.So the excavation effect should be adequately considered in the slope design.And the bearing capacity of the support engineering should fit the excavation effect of the multistage slopes.At last,the observed original data of the displacements and horizontal thrusts of the designated points in each slope-step from the centrifugal model test are listed.And the points are clearly marked in the illustration of model prescribed.From the centrifugal model test and numerical simulation,the horizontal thrust and unbalance forces curves of each designated point are drawn during excavation.