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Abstract Engineering projects of risk control in construction of Hangzhou Qingchun road cross-river tunnel are introduced. Contents include：causes of water leakage at the tunnel portal and soil collapse at the reinforced area when the shield setting out are put forward，moreover，avoidance and treatment measures are described. Reasons leading to the differences of settlements of the levee when two shields traversing it respectively are analyzed，and some construction measures for slurry shield to cross the levee are proposed. Reasons to the invalidation of the tail seal are studied，and techniques to shut off the groundwater using liquid nitrogen freezing method and repair the tail seal brushes in the artesian aquifer are presented. Engineering practices show that good tightness of the tunnel portal can avoid water leakage and soil collapse at the reinforced area，and optimization of parameters of shield driving can reduce disturbance to the levee while shield tunneling. On the contrary，sustainable rainfall and severe fluctuation of the chamber pressure lead to larger settlements. It is also shown that liquid nitrogen freezing method can seal off the groundwater safely and the repair of the tail seal brushes eliminates the risk of mud leakage of the shield tail successfully. These results would provide a scientific reference for risk control in similar shield tunnelling in practice.
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Received: 29 January 2010
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2011, Vol. 30 
