数值模拟方法在软土路基沉降因素分析中的应用

Application of Numerical Simulation Method in Analyzing of Settlement Factors of Highway Embankment in Soft Soils

软土路基工程的沉降严重影响公路的建设周期和使用寿命,产生路基沉降的主要影响因素有路基的填筑高度、填筑速率和排水效果,为研究这些因素对软土路基沉降的影响程度,采用MIDAS GTS有限元软件,建立软土-路堤二维平面模型,分析结果表明:(1)填方高度对软土路基的沉降影响作用明显,两者有较好的正相关关系,随着填方高度的增加,软土路基受到的竖向压力增加,加剧了路基的沉降;(2)填方速率对软土路基的沉降主要在软土的固结阶段,当固结完成后,路基的沉降值趋于稳定值,随着施工填筑速率的加快,路基沉降趋于稳定值的速率不同,在平均填筑速率为5 cm·d-1时,路基的填筑效果最好;(3)软土路基采用真空排水预压法处理时,塑料排水桩间距为1.2 m,真空压力为80 kPa时,排水固结效果最理想,路基最快达到沉降稳定。

The settlement in the soft soil subgrade project seriously affects the construction schedule and the service life of the roadway.The main factors that cause the settlement in the embankment include the embankment height,filling speed and the drainage characteristics of subgrade.In order to study the influence degree of these factors on the settlement in the embankment on soft soils,this paper uses the PLAXIS finite element software to establish the two-dimensional plane model of soft soil embankment,and the embankment is simulated by the Mohr Coulomb model.The creep model of soft soil is used to simulate the soft soil.The analysis results show that:(1) the embankment height has an obvious effect on the magnitude of settlement in soft soils,and there is a good correlation between the two.With the increase of embankment height,the vertical pressure in the soft soil increases,which increases the settlement of subgrade;(2)the settlement in the soft soil subgrade is mainly in the consolidation stage of soft soil,when the consolidation is completed,The settlement tends to stable.With the acceleration of construction filling rate,the settlement rate tends to stable.When the average filling rate is 5 cm/day,the filling effect of subgrade is the best;(3) when the vacuum drainage preloading method is adopted for constructing the embankment in soft soil,the distance between drainage path is one meter,and the vacuum pressure is 80 kPa,the drainage effect is the best,and the embankment reaches the stable settlement pattern quickly.