Open Cut Tunnel
Such tunnels often appear on mountain roads beside cliffs. One side is a mountain wall, while one side is supported by dozens of reinforced concrete columns, which are light-transmissive and not all enclosed by concrete walls. Therefore, the site where the Ming tunnel is built is usually a large collapsed side slope, which cannot be repaired. Most of the time, this method can only be used to deal with the soil and rock that may collapse from the mountain slope at any time. To prevent the falling rocks above these cliffs from hitting the road surface, causing damage to the roadbed, and interrupting traffic, similar to the principle of a canopy, let the rocks on the top of the cliff or the slope fall to the bottom of the cliff or through the slope of the canopy. River valley. Simply put, if a road close to the cliff wall is directly excavated, and the slope may slide and collapse, then the section of the road needs to be made into an open tunnel.
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About Ming Tunnel Reference Materials:https://zh.wikipedia.org/wiki/%E6%98%8E%E9%9A%A7%E9%81%93
