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Outline
To investigate the dynamic impact of straddle-type viaduct construction on existing metro tunnels, this study takes the Wangsheren Station to Wangsheren North Station section of Jinan Metro Line 6 as the engineering background. Field tests and numerical simulations were conducted to systematically analyze the deformation patterns of tunnels under the multi-stage coupled effects of "pile foundation excavation, foundation pit unloading, and bridge superstructure loading." The findings reveal that: (1) Foundation pit excavation induces significant tunnel uplift (maximum 4.62 mm), accompanied by horizontal contraction (maximum 1.74 mm) and vertical expansion (maximum 3.25 mm). After bridge loading, the tunnel subsides, with horizontal expansion and vertical convergence observed. (2) The clearance between the tunnel and foundation pit significantly influences uplift deformation: as the clearance increases from 6.7 m to 20 m, the uplift decreases from 5.74 mm to 0.90 mm (approaching zero at ≥15 m), while subsidence remains stable at approximately 5.2 mm. A clearance of ≥12 m is recommended for risk mitigation. (3) Stratigraphic characteristics dominate deformation responses: silty clay layers exhibit greater uplift during excavation (+1.2 mm), whereas gravelly sand layers experience more pronounced subsidence during bridge operation (–1.5 mm). Deformations in moderately and slightly weathered rock strata are negligible. (4) Interval construction of multiple pile caps reduces subsequent excavation-induced uplift (with a 12% reduction for the second pile cap), supporting a "alternate excavation" construction strategy. Innovatively, this study proposes a deformation prediction model based on stratigraphic heterogeneity, which overcomes the limitations of traditional homogeneous assumptions and provides a theoretical foundation for optimizing the design and risk assessment of straddle-type viaduct projects.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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