考虑黄河冲刷要求的盾构法隧道最小覆土厚度分析

发布时间：2018-11-04 12:04

【摘要】：针对兰州地铁1号线下穿黄河段盾构法隧道的最小覆土厚度问题,基于高压富水弱胶结砂卵石地层特性,分别提出由盾构掘削面稳定性与盾尾后方隧道抗浮稳定性决定的最小覆土厚度的修正算法,明确盾尾后方隧道受到的总浮力可以归纳为因浆液包裹产生的静态上浮力,以及地层应力引起的竖向不平衡力对应的动态上浮力,计算发现隧道抗浮稳定性要求的最小覆土厚度明显大于1.0 D(D为隧道直径),《地铁设计规范》(GB50517—2003)提出一般不宜小于1.0 D的最小覆土厚度有待进一步完善。在考虑隧址附近既有桥墩影响条件下,得出考虑冲刷要求的隧道最小覆土厚度方案是安全可行的,同时明确既有构筑物局部冲刷对新建构筑物的影响。研究结论可为盾构法隧道浅覆土穿越江河的稳定性控制奠定理论基础。
[Abstract]:Aiming at the problem of the minimum overlying soil thickness of shield tunneling under the Yellow River section of Lanzhou Metro Line 1, based on the characteristics of high pressure water-rich and weak cemented sand pebbles, A modified algorithm for the minimum overlying soil thickness determined by the stability of shield tunneling surface and the anti-floating stability of shield rear tunnel is proposed respectively. It is clear that the total buoyancy of shield rear tunnel can be reduced to static buoyancy caused by slurry wrapping. As well as the dynamic buoyancy corresponding to the vertical unbalance force caused by formation stress, it is found that the minimum overlying soil thickness required by the anti-floating stability of the tunnel is obviously greater than 1. 0 D (D as the tunnel diameter. The Design Code for Subway (GB50517-2003) puts forward that the minimum overlying soil thickness should not be less than 1. 0D generally, which needs to be further improved. Under the condition of considering the influence of the existing piers near the tunnel site, it is concluded that the minimum overlying soil thickness scheme considering the scour requirement is safe and feasible, and the influence of local scour of the existing structures on the new structures is clarified. The conclusion can lay a theoretical foundation for the stability control of shallow soil across rivers in shield tunneling.
【作者单位】：中铁第一勘察设计院集团有限公司;长安大学公路学院;
【基金】：长安大学中央高校基本科研业务费实验室开放基金(0009 2014G1502038) 国家自然科学基金资助项目(51209006) 长安大学中央高校基本科研业务费专项资金(0009 2014G1211008)
【分类号】：U455.43

【参考文献】