Free-flow tunnel used more round arch straight wall form cross-section.

无压隧洞多采用圆拱直墙形断面。

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There was a revival of ancient Roman forms, including the column and round arch, the tunnel vault, and the dome.

复兴古罗马的形式，包括廊柱和圆拱，地道的拱顶以及圆屋顶。

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There was a revival of ancient Roman forms, including the column and round arch, the tunnel vault, and the dome.

复兴古罗马的形式，包括廊柱和圆拱，地道的拱顶以及圆屋顶。

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