桩锚结构在复杂地质深基坑中的应用试验

海南东环铁路美兰机场隧道在厚砂层微承压水情况下的深基坑工程，因受复杂地质条件限制，将原设计围护结构中的3道钢支撑，通过试验优化为桩锚＋钢支撑围护，主要介绍了锚索试验段的试验方案、试验过程及锚索应力与桩顶位移等监控量测情况，并结合施工过程介绍了止水帷幕漏水、涌砂处理等。试验说明采用桩锚结构可行，加大了作业空间，提高了施工效率，简化了隧道施工工艺，缩短了工期。

Experimental Application of the Pile-anchoring Structure to the Deep,Complex Geological Foundation Pits

Owing to the limitation of the complex geological conditions of the deep foundation pit project of the Meilan Airport Tunnel of the East-ring Railway in Hainan, which is located in the stratum of thick sand and micro-pressure water, the originally-designed retaining structure consisting of bored piles plus water-stopping spun piles, steel supports and the dual I-steel retaining structure is optimized into a pile-anchoring-plus-steel-support retaining structure after being tested. The test schemes for the test sections of the anchoring cable, test processes, as well as the measuring of the stress of the anchoring cable and the displacement of pile tops, are dealt with in the paper, with the treatment of the water leakage of the waterstopping curtain, and sandy gush in the course of construction introduced. Test results show that the adoption of the pile-anchoring structure is feasible, which helps enlarge the construction clearance, improve the construction efficiency, simplify the tunneling processes and shorten the construction duration.