Study On Surface Consolidation Settlement Of Shield Tunnel

The long term post-load settlement before tunnel operation was researched. It contains construction settlement and post-load consolidation settlement. From analytical method and numerical method et al, the characteristics and shortcomings of the research contents were pointed out, and current key research topics together with some new research ideas were also proposed.Based on the statistical analysis of current excess pore water pressure material caused by shield tunnel construction, the law of dissipation of excess pore water pressure law was obtained, and the current monitoring method defects was also put forward. Meanwhile, some current problems such as the time of measured pore pressure dissipated time is short, when excess pore water pressure reached its peak time, when the consolidated time starts and the distribution model of excess pore water pressure within the distributed range were all discussed.The formula was deduced by stress relief theory, and its value within the region of its distribution at any point was subsequently deduced by stress transfer theory. The research result showed that:With the increase of distance from shield tunnel central axis, the initial excess pore water pressure decreased in a concave curve shape. When reducing the diameter of the shield or increasing tunnel depth, the differences between the initial soil pore water pressure at the bottom of tunnel and the initial soil pore water pressure at the tunnel center level would be larger.The post-load consolidation settlement is caused by consolidation settlement the dissipation of pore pressure and tunnel leaks. The consolidation settlement above shield tunnel axis was not only considered the soil consolidation settlement above the top of the tunnel, but also was considered the consolidation settlement at the bottom of shield. Using hydrodynamic theory, the consolidation settlement caused by cracks constant free flow in cracks was deduced. The long term post-load settlement can be calculated when the leakage is uniform. It is verified by an example, so it can be better used to predict long-term post-load settlement.