马蹄形盾构的工程应用解析

相较于圆形断面,马蹄形隧道有空间利用率高的优势,浩吉铁路白城隧道在国内首次采用马蹄形土压平衡盾构施工,具有安全、快速、环保的特点。通过梳理盾构施工的统计数据,发现其月平均施工效率达203 m,且每环拼装效率为38～43min,但突遇姜石地质给施工带来很大的困难。本文阐述了盾构4个施工阶段的应用效果,解析了开挖盲区对多刀盘开挖和推进系统的影响、渣土改良和双螺旋输送机对陕北黄土地质施工的应对措施、马蹄形管片拼装机在应用中的优势与不足。为拓宽马蹄形盾构适用地质领域和提高施工效率,建议盾构今后的技术突破方向：全断面仿形刀盘的开发和管片拼装系统的智能化,前者可实现盾构无盲区开挖、提升出渣系统效果和降低总推力的需求,后者有利于减少人员操作难度,提高拼装工艺的精准度。

Analysis of Engineering Application of HorseshoeshapedShield

Compared with circular tunnel, the horseshoeshapedtunnel has the advantage of high space utilization rate. Hence, the horseshoe shaped EPB shield has been applied to Baicheng Tunnel on HaolebaojiJi′an Railway in China for the first time,which realized safe, rapid and environmentally friendly construction. Based onthe shield tunneling data statistic, it is found that the average constructionefficiency reached 203 m per month, the segment assembly efficiency reached38~43 min, and great challenges were encountered when tunneling in Gingerolitegeology. In this paper, the application effect of shield in 4 constructionstages are introduced, and the influence of excavation blind area on compositecutterhead and thrust system, the countermeasures of the soil conditioning andthe double screw conveyor system under loess geological condition in northernShaanxi, and the advantages and disadvantages of horseshoe shaped segment erector in application are analyzed. In order topromote the widely application of horseshoe shapedshield in more and more geological fields and improve the constructionefficiency, some suggestion for the future developing direction of shield thatdeveloping full cross section profiling cutterhead andthe intellectualization of segment assembly system, which can realize full areaexcavation, improve the efficiency of mucking system, reduce the total thrust,reduce the difficulty of personnel operation and improve the accuracy of theassembly process, is provided.