基坑支护形成与边坡位移的相关性分析

通过一超深基坑工程案例，根据现场监测数据探讨了复合土钉、灌注桩-锚杆等支护形式与基坑边坡位移的相关性．分析表明，对于复合土钉支护，加强对开挖浅层土时基坑边坡位移的控制(如在基坑浅部加大土钉长度、减小间距或较早设置预应力锚杆并加大其长度)，对于有效控制基坑开挖过程中的边坡位移及其发展态势具有重要意义．工程实践表明，在严格的保证施工质量条件下复合土钉支护结构可以应用于挖深超过18m的深基坑工程中。

Correlativity between slope displacement and form of braced structure for deep foundation pit

According to the excavation depth, the soil properties and the adjacent engineering environment, 6 different forms of retaining structure, such as composite soil nail and anchored pile of concrete cast-in-place, etc., were employed for deep excavation in the same project. Based on the in-situ monitoring data, the correlativity between slope displacement and the forms of retaining structure is analyzed. For composite soil nailing, the analysis shows that, the very effective way to strictly control the slope displacement is to emphasize on carefully designing the bracing forms in early excavating phase which could be achieved by such ways as lengthening the soil nail or prestressed anchor in upper part of the retaining wall, etc.. The engineering practice also shows that the composite soil nailing could be applied in foundation pit with excavating depth greater than 18m which is forbidden by the Code (YB9258-97).