高填土路堤粉喷桩和土工格栅联合加固性状的数值分析

Numerical analysis of characters after reinforcement of powder spurting pile combined with geogrid in high embankment

应用FLAC-3D程序对某大桥28号桥台试验区17 m高的粉喷桩与土工格栅联合加固填土路堤进行了数值分析,计算结果和实测结果的对比表明:联合加固后,路基中心沉降明显减小,但坡角处沉降影响较小,因此,可以采取优化布桩的原则,减少工程成本;联合加固可以限制侧向位移,使得路堤的整体稳定性提高,有利于快速施工,同时加固区内桩身出现应力集中现象;加固区沉降量有明显减小,但下卧层沉降量不降低反而有一定程度增大,因此建议粉喷桩宜穿透软弱层,坐落在持力层上;联合加固后下卧层顶面附加应力有向路基中心集中的趋势;使用粉喷桩处理表层软弱而下层坚实的地基土效果将更为理想。

The reinforcement mode of powder spurting pile combined with geogfid in 17 meter high embankment at one No. 28 bridge abutment test zone is analysed numerically by FLAC-3D. Accordingly ,by a comparison between eomputation and actual measurement, some conclusions are as follows. Firstly, there is obvious reduction in settlement of embankment center but little at toe of side slope after combined reinforcement, so the optimized pile disposal should be applied to eeonomization;Secondly, eombinod reinforcement can limit lateral displacement and enhance the stability to be convenient for construction while some stress concentration appears in piles; Thirdly,there is obvious reduction in settlement of reinforcement region but some increase in underlying soil layer instead, so it is advised that Powder Spurting Pile should penetrate soft soil to rest on bearing stratum; Fourthly, there is a trend of additional stress converge on embankment center in underlying soil layer. Finally, it is more appropriate to apply eombined reinforcement to foundation soil which is soft in surface layers but firm in deep layers.