Finite Element Analysis of Effects of Improvement of Soil Between Double-Row Piles

Abstract

Abstract:Double-row pile (DRP) retaining systems have been widely used in deep excavations in China. Soil between the front and back-row piles (FBP soil) is often improved to decrease the displacement of DRPs in soft soil areas, but the improvement efficiency has rarely been researched. A large and deep excavation supported by a DRP retaining system is introduced, and the effect of FBP soil improvement is discussed by comparing the finite element analysis and the monitoring results. Then, a parametric study of DRP using the finite element method considering the small strain of soil is conducted to investigate the effect of FBP soil improvement. It was shown that the pile deflection and bending moment decrease when the FBP soil is improved. Moreover, the most efficient way to minimize the pile deflection and bending moment is to improve the FBP soil around the excavation level. The FBP soil improvement 2—4 m below the pile head is not very useful for reducing the pile deflection and can be eliminated when the pile displacement limit is not very strict.

Key words:large excavation, double-row pile (DRP), soil improvement, deflection, bending moment, finite element analysis

摘要：双排桩支护系统在中国深基坑工程中得到了广泛的应用。在软土地基地区，常对前后排桩桩间土进行改良，以减小双排桩的位移，但其改良效果研究较少。以某大深基坑为例，通过有限元分析与监测结果对比，讨论了前后排桩桩间土体改良的效果。在此基础上，采用考虑土体小应变的有限元法进行了双排桩参数化研究，探讨了前后排桩桩间改良土体的效果。结果表明：改良前后排桩桩间土后，桩身挠度和弯矩减小。同时，改善开挖水平周围的前后排桩桩间土是减小桩身挠度和弯矩的最有效途径。在桩顶以下2~4 m处进行前后排桩桩间土改良对减小桩挠度作用不大，在桩位移限制不是很严格的情况下可以消除。

关键词:大基坑，双排桩，土体改良，挠度，弯矩，有限元分析

CLC Number:

TU 473

NIE Dongqing^1∗(聂东清), ZHAI Zhiyang¹(翟之阳), ZHANG Wei¹(张威), LI Zhi²(李志). Finite Element Analysis of Effects of Improvement of Soil Between Double-Row Piles[J]. J Shanghai Jiaotong Univ Sci, 2024, 29(5): 919-929.

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