不同桩长对无持力层刺入工况下刚性网格-桩加固路基的影响

INFLUENCE OF DIFFERENT PILE LENGTHS ON RIGID GRID-PILE REINFORCED SUBGRADE WITHOUT BEARING STRATUM PENETRATION

根据刚性桩复合地基和桩承式路堤在有持力层刺入工况下的薄弱部位,分析刚性网格–桩复合地基中张拉网、刚性网格和附加桩对薄弱处的加固作用,研究有、无持力层刺入2种工况下刚性网格–桩复合地基受力和变形在不同桩长影响下的变化特征,对刚性网格–桩复合地基是否适用于无持力层工况进行可行性探讨。研究结果表明:在无持力层刺入工况下,刚性网格–桩复合地基大部分边桩弯矩和剪力较大,当桩长缩小,其分布区域向路堤中心方向扩散;当桩长增加,大部分桩桩体荷载比增大,边桩弯矩及剪力、路堤沉降和路堤外侧竖向变形减小;可通过增加桩长,利用PTC管桩放宽中桩截面,减小附加桩桩径,使刚性网格–桩复合地基实现优化并适用于无持力层刺入工况。

According to weak regions of rigid pile composite foundation and piled embankments with bearing stratum penetration, the reinforcement of weak regions by using stretching net, rigid grid and additional pile of rigid gird-pile composite foundation was analyzed. The changing characteristics of force and deformation of rigid grid-pile composite foundation with and without bearing stratum penetration were investigated under different pile lengths; and the feasibility whether the rigid grid-pile composite foundation is applicable to the case without bearing stratum penetration was evaluated. The results show that, without bearing stratum penetration, the bending moment and shear force of most side piles are large, and their distribution regions would increase along the direction of embankment center when the pile length decreases. When the pile length increases, the load ratio of most piles increases, and the bending moment and shear force of side pile, embankment settlement and vertical deformation outside the embankment decrease. By increasing the pile length, applying PTC pile to enlarging the cross-section of central pile, and decreasing the additional pile＇s diameter, the rigid grid-pile composite foundation can be optimized and be applicable to the case of bearing stratum penetration.