筏板基础下碎石桩改良软土地基性能的数值研究

为解决传统碎石桩加固软土地基研究中忽视碎石桩侧向膨胀的问题，在对筏板基础下碎石桩排水荷载条件下加固软土地基的性能进行评估的基础上，利用PLAXIS 3D数值模拟方法研究了桩间距、直径和桩长等参数对筏板基础长期性能的影响，同时分析了各参数对筏板基础整体沉降、弯矩和碎石桩侧胀的影响。结果表明：1）软土中碎石桩的存在显著降低了筏板基础的沉降和弯矩；2）碎石桩的侧向胀形分布取决于其位置的深度；3）筏板基础的沉降、弯矩和侧向胀形随着间距与桩径比的减小、面积置换率和碎石桩长度的增加而增加；4）采用长厚比为0.75的碎石桩加固软土，可以达到良好的加固效果。研究结果对于全面了解筏板基础下碎石桩改良软土的侧胀性状具有重要意义，对于今后类似工程加固设计具有参考借鉴价值。

Numerical study on performance of soft soil foundation improved by gravel piles under raft foundation

In order to solve the problem that the lateral dilation of gravel piles was ignored in the traditional research of reinforcing soft soil foundation with gravel piles, the performance of reinforcing soft soil foundation with gravel piles and raft foundation under drainage load was evaluated in this paper. Based on this, the influence of pile spacing, diameter and pile length on the long-term performance, settlement of raft foundation, bending moment and lateral dilation of gravel pile was studied by using PLAXIS 3D numerical simulation method. The results show that: 1) the settlement and bending moment of raft foundation are significantly reduced due to the existence of gravel piles in soft soil; 2) the lateral dilation distribution of gravel piles depends on the depth of their location; 3) the settlement, bending moment and lateral dilation of raft foundation increase with the decrease of pile spacing and diameter ratio, and the increase of area replacement rate and gravel pile length; 4) gravel piles with length thickness ratio of 0.75 are used to reinforce soft soil, and good reinforcement effect can be achieved. The research results are of great significance to understand the lateral dilation behavior of soft soil improved by gravel piles under raft foundation, and have important reference value for the reinforcement design of similar projects in the future.