A Construction Method for Preventing Instability of Shield Tunneling in Highly Sensitive Stratum Conditions

Abstract

The invention discloses a construction method for preventing the instability of a shield tunnel under high-sensitivity formation conditions, comprising the steps of: 1. arranging surface monitoring points; 2. installing grouting anchoring conduits; 3. determining grouting pressure and grouting amount 4. Grouting under pressure; 5. Judging whether the surface is uplifted; 6. Judging whether the grouting pressure and grouting amount reach the design value; 7. Troubleshooting; 8. Stop grouting under pressure and block the hoisting holes; 9. The tunnel segments of the same ring forming the working face are reinforced ring by ring in the tunnel section to be monitored. The invention effectively supplements the shortage of synchronous grouting in shield tunneling under the condition of high-sensitivity strata, performs secondary filling behind the wall, increases the range of post-grouting filling and reinforcement of the tunnel segment wall, improves the ability of the segment to withstand external forces, and resists tunnel settlement. At the same time, the grouting anchor conduit can provide effective support for the lining segment, improve the overall stability of the shield tunnel, and effectively curb the risk of deformation and instability of the shield tunnel during construction and operation.

Description

technical field [0001] The invention belongs to the technical field of preventing tunnel instability, and in particular relates to a construction method for preventing the instability of a shield tunnel under high-sensitivity stratum conditions. Background technique [0002] If the formation contains a large amount of saturated fine sand and silt, forming 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 very easy to 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 quality hidden dangers are still relatively large, which affects the smooth construction and safe operation of the project. When shield tunnels...

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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