Single-hole double-layer overlapping tunnel structure and construction method thereof

The invention provides a single hole double layer overlapping tunnel structure including the single hole tunnel which the high side wall with the high/stride ratio is bigger than 2, the composite lining structure in the single wall and the upper/lower overlapping tunnel set in the middle of the high side wall. The invention also provides the constructing method. The invention can build the two-line tunnels in the limit room under ground and decrease the environment influence, the underpinning number of the pile foundation and the cost.