北京地区基坑支护技术的发展与工程实践

北京地区土体具有非饱和土特点，基坑失稳多与水的影响有关。基坑支护方法多采用不同支护形式的组合，新技术进展主要集中在锚固技术方面，土钉支护计算一般为内部稳定控制。土钉端部与面板的连接构造极为重要，与预应力锚杆结合形成的复合土钉是一种可靠有效的支护形式，对于多支锚体系，应通过实测数据的积累，建立符合当地实际的土压力修正模型；荷载分散型锚杆可大幅度提高锚杆的锚固效率，荷载分散型锚杆的张拉宜采取等荷载同步张拉方法，可拆芯式锚杆技术是避免地权法律纠纷的有力手段。

Pit support technology development and engineering practice in Beijing

The soils in Beijing usually have characteristics of unsaturated soil; pit instability is more related with impact of water. The excavation supports have more different portfolio forms. The new technology developments are in anchoring technology. Calculation of soil nailing is generally for internal stability control. The node structure in the connecting of face and soil nailing is extremely important; the soil nailing combining with prestressed anchors is a reliable and effective form of support. For multi-anchorage system, by the accumulation of measured data, establishing soil pressure correction model of local conditions is meaningful. By load-dispersive anchor, the anchorage efficiency can be increased substantially. The identical load and synchronous tension method should be adopted to tension test of load-dispersive anchor. The removable anchor is a powerful tool to avoid legal disputes.