深基坑双排桩支护排距室内模型试验研究

为了研究深基坑双排桩支护结构最佳排距及支护结构内力,分别对2D、3D、4D和5D(D为桩径)4种排距的双排桩支护结构进行室内模型试验,通过千斤顶在基坑顶加压模拟荷载,不同开挖深度下,测量模型桩身内力大小及桩顶位移的变化.分析排距和开挖深度对双排桩支护结构的影响,包括前后桩正负弯矩大小、差值、桩顶位移等,得出双排桩支护结构的最佳排距.研究表明:双排桩支护排距变化,对桩弯矩及桩顶位移影响均较大,且双排桩排距的变化对后排桩的内力影响明显大于前排桩,对正弯矩的影响小于对负弯矩的影响;开挖深度对桩顶位移影响较大,对正弯矩的影响大于负弯矩,深度位移曲线近似为过原点的二次曲线,基坑底以上为正弯矩,坑底下为负弯矩,3D排距时桩顶位移最小,4D排距时正弯矩最大.

Indoor Model Test Study on Row Spacing of Double-row Piles Supporting Deep Excavation Pit

In order to study the optimal row spacing and supporting structure internal forces of the double-row piles supporting structure of deep foundation pit, indoor model tests were carried out for double-row piles supporting structure with row spacing of 2D, 3D, 4D and 5D (D is the diameter of the pile), respectively. Jacking forces were applied to simulate the load of different excavation depths, and the stress in the pile and the displacements at the top of the piles were measured. The effects of row spacing and excavation depth on bending moment and the displacement of these two rows of piles in the double-row piles supporting system were analyzed, and the optimal row spacing was obtained. This research shows that the change of row spacing causes large influences on both the bending moment of the pile and the displacements at the top of the pile. The change of row spacing affects the internal stress of the back pile much more than that of the front pile. It affects the positive bending moment more than the negative bending moment. The curve of depth-displacement is approximately a quadratic function curve passing the origin. It is positive bending moment in the pile above the foundation pit, and it is negative bending moment in the pile below the foundation pit. The displacement at the top of the pile reaches the smallest value when the row spacing is 3D, and the positive bending moment reaches the maximum value when the row spacing is 4D.