土工格栅加筋地基承载特性数值分析

Numerical Analysis of Bearing Characteristic of Geogrid Reinforced Foundation

为研究加筋地基承载性能,基于已有室内试验结果采用有限差分法建立加筋地基数值模型,分析竖向荷载下土工格栅加筋地基的力学特性及加筋层数对土体的荷载-沉降变形特性、应力分布及土工格栅位移的影响,探讨筋土结构的内部土体和土工格栅应力位移场的演变规律,引入承载力提高系数综合分析加筋层数对加筋地基的沉降及承载力的影响。研究表明:在竖向荷载作用下,地基土体呈拱状不均匀沉降,基础两侧土体隆起变形,加筋后能够改善地基的不均匀沉降及减小侧向变形,约束基础两侧土体的隆起;土工格栅具有良好的应力扩散作用,加筋地基的承载力随着加筋层数的增加而增加,但增长幅度逐渐变缓,加筋层数为4层时承载力最高,为最佳加筋层数;土工格栅的有效埋深约为1.5 B(B为基础宽度),当筋材埋深超出筋材有效深度影响范围,筋材的加筋作用不再增强。

In order to study the bearing capacity of reinforced foundation,the numerical model of reinforced foundation was established by the finite difference method based on the existing laboratory test results.It analyses the mechanical properties of reinforced foundation under vertical loads and the effects of reinforced layers on pressure-settlement deformation characteristics,stress distribution of soil and displacement of geogrid were analysed.And it explore the evolution law of stress-displacement field on reinforced structure and geogrid.It also introduces bearing capacity improvement factor and comprehensively analyse the influence of reinforcement layers on the settlement and bearing capacity of reinforced foundation.The results show that the soil has an arched uneven settlement deformation and the soil on both sides of foundation appears uplift deformation under vertical loads,however reinforced soil can improve the uneven settlement of the foundation and reduce the lateral deformation and constrain the uplift of soil on both sides of the foundation.The geogrid has good stress diffusion.The bearing capacity of the reinforced foundation increases with the increase of reinforced layers,but the growth rate gradually becomes slower.When the number of reinforced layers is 4,the bearing capacity is the highest,which is the best number of reinforced layers.The effective laying depth of geogrid is 1.5 B.When the depth of the reinforcement exceeds the effective depth,reinforced effect cannot be seen.