城际铁路下穿南水北调干渠设计方案研究

城际铁路下穿南水北调中线干渠工程,国内尚属首例,干渠沉降变形控制要求严,工程实施难度及风险大。基于新郑机场至郑州南站城际铁路的工程背景,从对机场与航空港区规划及机场电磁环境影响等方面,比选确定城际铁路下穿干渠的交叉方案。考虑工法对地层的适应性、干渠结构变形、风险可控性、工程投资等因素,研究确定大直径盾构下穿干渠的施工工法。提出盾构以2D埋深下穿干渠的沉降变形控制标准,即渠道坡顶、坡脚最大变形差≤1 mm/m,渠道位移(+10～-5) mm、变形速率≤2 mm/d。采用有限元软件对盾构穿越干渠过程进行数值模拟,干渠沉降可控、不影响结构安全。对盾构下穿干渠风险进行系统分析,提出切实可行的工程对策措施,以降低或规避风险,确保隧道施工及干渠运行安全。

Design Scheme for Intercity Railway Passing under the Main Channel of South-to-North Water Diversion Project

The intercity railway passing under the south-to-north water diversion middle route project is the first to be built in China. The settlement control standard for the main channel is high and its implementation is very difficult and risky. Based on the intercity railway from Zhengzhou Airport to Zhengzhou South Railway Station, this paper conducts comparison of several schemes in terms of the intercity railway's impact on airport planning, airport economy zone planning and airport electromagnetic environment, and recommends the intersecting scheme of the intercity railway undercrossing the main channel. In consideration of the construction method adaptability, the main channel settlement, risk controllability and project investment, this paper studies and adopts the construction method of large-diameter shield tunnel undercrossing the main channel. This paper puts forward settlement control standard for the main channel, and recommends that maximum deformation difference from the bottom to the top of a slope be less than 1 mm/m, channel displacement between +10 mm and-5 mm and the rate of deformation less than 2 mm/d. The finite element software is employed to simulate the process of shield tunneling and the results show that the main channel settlement is in a controllable range and would not affect the safe operation. Finally, this paper analyzes systematically the risk of the intercity railway undercrossing the main channel, proposes feasible engineering countermeasures to reduce risk and ensure safety of tunnel construction and operation for the main channel.