Construction method for preventing instability of shield tunnel under high-sensitivity stratum conditions

Abstract

The invention discloses a construction method for preventing instability of a shield tunnel under high-sensitivity stratum conditions. The construction method comprises the steps of 1, arranging surface monitoring points, 2, installing grouting anchoring guide pipes, 3, determining grouting pressure and grouting amount, 4, grouting under pressure, 5, judging whether the surface is uplifted or not,6, judging whether the grouting pressure and the grouting amount reach design value or not, 7, troubleshooting, 8, stopping grouting under pressure and plugging a lifting hole and 9, one by one reinforcing tunnel segments of same rings which form a working surface in a tunnel section to be monitored. The deficiencies of synchronous grouting during shield tunneling under the high-sensitivity stratum conditions are effectively overcome, secondary filling is carried out at the backs of walls, the scope of grouting, filling and reinforcing of the backs of the walls of the tunnel segments is increased, the ability of the segments to withstand external forces is improved, and tunnel settlement deformation is resisted; and meanwhile, the grouting anchoring guide pipes can provide effective support force to lining segments, the overall stability of the shield tunnel is improved, and the risks of deformation and instability of the shield tunnel during construction and operation are effectivelyavoided.

Description

Technical field [0001] The invention belongs to the technical field of preventing tunnel instability, and particularly relates to a construction method for preventing instability of a shield tunnel under high-sensitivity ground conditions. Background technique [0002] If the formation contains a large amount of saturated fine sand and silt to form a weak formation with strong water permeability and high compressibility, this type of formation is called a high-sensitivity formation. The high-sensitivity formation has thixotropic characteristics and is extremely easy to move under dynamic action. The soil is damaged and deformed, the excavation surface is unstable, and the ground subsides. With China's vigorous development of underground space and three-dimensional transportation network, the shield industry has made great progress, but the project risks and hidden quality problems are still large, which affects the smooth construction and safe operation of the project. When shie...

AI Technical Summary

Problems solved by technology

With China's vigorous development of underground space and three-dimensional traffic network, the shield tunneling industry has made great progress, but the project risks and quality hidden dangers are still relatively large, which affects the smooth construction and safe operation of the project

When shield tunnels are excavated in high-sensitivity strata and shield tunnels are received, due to sudden water gushing and water penetration, segments are deformed and unstable, and tunnel damage occurs frequently. The settlement and deformation of operating tunnels exceeding the standard and affecting operational safety have become prominent, seriously affecting The surrounding environment and the safety of people's life and property

At present, most domestic shield construction tunnel structures are prefabricated assembled segments, and grouting is filled behind the wall. Generally, shield construction tunnels have not formulated targeted measures for high-sensitivity water-rich strata, either in design or construction specifications. It is still processed according to conventional measures, that is, grouting behind the wall within about 150mm outside the segment, and the filling coefficient should be 1.3-2.5 according to the specification. The overall stability of this structure is slightly insufficient under high-sensitivity and complex geological conditions. In the construction and operation stages, tunnel surges and deformations are prone to accidents that lead to the instability and collapse of formed tunnel segments.

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