Advanced compaction grouting reinforcement method for loose and weak strata suitable for shallow buried tunnels

Abstract

The invention discloses a pre-compacting and grouting reinforcement method for loose and weak strata suitable for shallow-buried tunnels, which includes testing the compaction performance of the stratum when the tunnel passes through the loose and weak stratum through experiments, and determining the ability of the stratum under different grouting pressures. The degree of compaction achieved, and the mechanical properties and impermeability properties corresponding to different compaction degrees; analyze the influence of different compaction degrees of formations and the thickness of the grouting reinforcement ring on the stability of tunnel excavation, so as to determine the target grouting pressure, grouting The thickness of the grout reinforcement ring; determine the maximum expansion radius of the expansive geotextile bag and the arrangement spacing of the grouting holes on the surface; make the grouting pipe with the expansive geotextile bag; implement the grouting hole drilling operation on the surface, and drill the grouting hole after reaching the predetermined depth. Insert the grouting pipe with expansive geotextile bag; use quick-setting grouting material for grouting, and stop grouting when the grouting pressure reaches the target grouting pressure; fill the gap between the grouting pipe and the grouting hole Closed; complete grouting of all grouting holes.

Description

technical field [0001] The invention relates to the field of tunnel construction, in particular to an advanced compaction and grouting reinforcement method for weak strata suitable for shallow-buried underground excavation tunnels Background technique [0002] Urban subway tunnels are generally shallow-buried tunnels. During the construction of subway tunnels, they often pass through loose and weak strata of the Quaternary system, such as water-rich sandy soil layers and soft clay layers. In the process of tunnel excavation, it is very easy to induce engineering accidents such as tunnel collapse, which seriously threatens the safety of tunnel excavation. Grouting is an effective means of strengthening loose and weak strata. This method strengthens the loose and weak stratum in front of the tunnel face by grouting in advance to improve the mechanical properties and impermeability of the stratum, thereby ensuring the tunnel excavation process. surrounding rock stability. The...

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Problems solved by technology

However, the above methods all have the following disadvantages: ① It is difficult to control the grout diffusion. Since the grout diffuses mainly in the form of splitting in the formation, the grout diffusion radius is generally much larger than the target grouting reinforcement range, the effective retention rate of the grout is low, and the grout is seriously wasted; ② The reinforcement effect is difficult to guarantee. Due to the low resistance to grout splitting and diffusion, the grouting pressure is low (generally <1MPa), the compaction degree of the formation under the grouting pressure is low, and the mechanical properties and impermeability of the formation do not increase. significantly

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