双排桩支护结构在临近地铁基坑中的应用

Application of Retaining and Protection Structure with Double-Row-Piles Wall for an Excavation Nearby the Subway

通过对双排桩支护结构计算模型和受力机理的深入研究,探寻双排桩悬臂结构安全稳定设计的关键控制点。以某临近地铁基坑支护项目为例,分别从高压旋喷加固桩间土提高桩间土体土弹簧水平刚度、桩顶盖梁两端设置水平受力构件增加盖梁整体侧向抗弯刚度、坑底加设配筋垫层增加整体抗倾覆安全系数、控制前排桩底持力层和沉渣厚度并辅以后压浆工艺缩小前后排桩间沉降差等四方面着手采取相应处理措施,取得良好应用效果,为双排桩的应用积累了经验。

Based on the calculation model and mechanical mechanism of retaining and protection structure with double-row-piles wall,the key control points for the safety and stability design of double-row-piles were explored.An excavation project nearby subway was taking as an example,four aspects of measures were carried out to control the safety and stability of the excavation.These four measures were:the high pressure jet grouting reinforcement was used to improve level of soil spring stiffness of soil between piles,the beam of top pile on both sides of excavation were set to increase plate beam lateral bending stiffness,cushion layer with reinforcing steel bar were added in the bottom of the excavation to increase overall resistive overturning safety factor,the bottom force-hearing layer of the front row pile,the thickness of sediment were controlled.In addition,the different settlement between front and post-pile was reduced by post grouting.Good results have been obtained and experience has been accumulated for the application of double row piles.