深基坑土钉和预应力锚杆复合支护方式的探讨

Research on composite support pattern of soil nails and prestressed anchors in deep foundation pits

土钉与预应力锚杆的复合支护方式是当前基坑工程中经常采用的支护方式。结合工程实例,利用有限元软件PLAXIS,合理选择本构模型,对土钉和预应力锚杆复合支护方式和土钉墙两种支护方式的基坑边坡稳定系数和边坡变形进行了分析。分析结果表明,在土钉和预应力锚杆的复合支护方式中,预应力锚杆的位置比较重要,通常锚杆的位置越靠近坡顶,则锚杆发挥的作用越大,效果越理想;土钉和预应力锚杆的复合支护方式与土钉支护相比,位移有所减小,但合理选择锚杆的数量和预应力值对最终效果有一定影响;基坑边坡的局部放坡有利于控制基坑坑口的最大水平位移。

The composite support pattern of soil nails and prestressed anchors are commonly adopted in the projects of deep foundation pits. By using the FEM program of PLAXIS and choosing appropriate material models, the support pattern of soil nails and prestressed anchors and the pattern of soil nail walls are analyzed. Then the slope stability of foundation pits is studied; and it is shown that the location of prestressed anchor is vital in the composite support pattern. The closer the anchor is to the top of the slope, the more useful the anchor is and better the effect is. Compared with support pattern of soil nails, the displacement of soil nails and prestressed anchor tends to reduce. However, the number of anchors and the value of prestress have some effects on the final result; and the localized inclined ramp is beneficial to control the maximum horizontal displacement of the pithead.