黄土地层浅埋小净距非对称断面隧道施工方案优化

(1.西安建筑科技大学 土木工程学院,陕西 西安 710055; 2.陕西省岩土与地下空间工程重点实验室(西安建筑科技大学),陕西 西安 710055; 3.中国铁建大桥工程局集团有限公司 天津 300300; 4.中铁北京工程局集团第一工程有限公司,陕西 西安 710100)

隧道工程; 非对称断面; 小净距隧道; 数值模拟; 施工方案

Optimization of construction scheme for shallow buried tunnel with small spacing asymmetric section in loess stratum
SONG Zhanping1, 2,WANG Shuangyuan1,SU Chunsheng2, 3,PAN Hongwei4,WEI Shoufeng3

(1.School of Civil Engineering, Xi'an Univ. of Arch.& Tech., Xi'an 710055, China; 2.Shaanxi Key Laboratory of Geotechnical and Underground Space Engineering(XAUAT), Xi'an 710055, China; 3.China Railway Construction Bridge Engineering Bureau Group Co.,Ltd.,Tianjin 300300, China; 4.China Railway Beijing Engineering Bureau Group First Engineering Co.,Ltd.,Xi'an 710100, China)

tunnel engineering; asymmetrical section; small spacing tunnel; numerical simulation; construction plan

DOI: 10.15986/j.1006-7930.2022.05.002

备注

在黄土地层中进行浅埋非对称小净距地铁隧道施工时极易引起围岩变形和沉降过大等工程问题.为优化该特殊地质条件下隧道的施工方法,本文以西安地铁四号线雁南四路站——大唐芙蓉园站存车区间小净距隧道为工程背景,对右隧先行和左隧先行两种开挖方式进行了数值分析.结果显示两种开挖方式完成后地表沉降稳定值为23.5 mm、23.9 mm,右隧拱顶沉降稳定值为31.5 mm、31.7 mm,左隧拱顶沉降稳定值为22.0 mm、22.3 mm,几乎没有差别.右隧先行时1#导洞至4#导洞最大水平收敛值是左隧先行的0.80倍、0.86倍、0.79倍、0.90倍; 左隧最大水平收敛值是左隧先行的0.54倍,这表明右隧先行能够有效的减小围岩水平收敛值.两种开挖方式下右隧围岩最大主应力为0.22 MPa、0.25 MPa,左隧围岩最大主应力为0.19 MPa、0.16 MPa,差别很小,两种开挖方式开挖完成后塑性区分布相似.最后对比模拟结果与监测数据发现数值差异较小且具有相同的规律性.该工法已成功应用于西安地铁4号线存车区间隧道,可为后续非对称小净距隧道施工提供参考和借鉴.
It is easy to cause the deformation and settlement of surrounding rock during the construction of shallow underground tunnel with asymmetric small spacing in loess stratum. In order to optimize the tunnel construction method under the special geological condition, this paper takes the small spacing tunnel between Yannan Fourth Road Station and Datang Furongyuan Station of Xi'an Metro Line 4 as the engineering background, and carries out numerical analysis on the two excavation methods of right tunnel first and left tunnel first. The results show that the stable settlement values of the ground surface after the completion of the two excavation methods are 23.5 mm and 23.9 mm respectively, the stable settlement values of the right tunnel vault are 31.5 mm and 31.7 mm, and the stable settlement values of the left tunnel vault are 22.0 mm and 22.3 mm, with almost no difference. The horizontal convergence values of 1# hole to 4# hole are 0.80 times, 0.86 times, 0.79 times and 0.90 times higher than that of the left tunnel first. The maximum horizontal convergence value of the right tunnel is 0.54 times that of the left tunnel first, which indicates that the right tunnel first can effectively reduce the horizontal convergence value. Under the two excavation methods, the maximum principal stress of the surrounding rock of the right tunnel is 0.22 MPa, 0.25 MPa, and the maximum principal stress of the surrounding rock of the left tunnel is 0.19 MPa, 0.16 MPa. The difference is very small, and the plastic zone distribution after the excavation according to the two excavation methods is similar. Finally, comparing the simulation results with the monitoring data, it is found that the numerical difference is small and has the same regularity. This method has been successfully applied to the car-storage interval tunnel of Xi'an Metro Line 4, which can provide reference for the subsequent construction of asymmetric small spacing tunnel.