Method for advanced compaction grouting reinforcement of spongy stratum suitable for shallow-buried excavation tunnel

Abstract

The invention discloses a method for advanced compaction grouting reinforcement of a spongy stratum suitable for a shallow-buried excavation tunnel. The method comprises the following steps that: a stratum compaction performance of penetration of a tunnel into a spongy stratum is tested by the experiment and thus compaction degrees of the stratum under different grouting pressures as well as mechanical and anti-penetrability performances corresponding to different compaction degrees are determined; influences on tunnel excavation stability by the different stratum compaction degrees and grouting reinforcement ring thicknesses are analyzed, so that a target grouting pressure and a grouting reinforcement ring thickness are determined; a maximum expansion radius of an expansive soil geotextile bag and an earth surface grouting hole arrangement interval are determined; a grouting pipe with the expansive soil geotextile bag is made; grouting hole drilling work is carried out on the earth surface and the grouting pipe with the expansive soil geotextile bag is inserted after the grouting holes reache a predetermined depth; grouting is carried out by using a quick-setting grouting materialand grouting is stopped when the grouting pressure reaches the target grouting pressure; the gaps between the grouting pipe and the grouting holes are filled and sealed; and grouting work of all grouting holes is completed.

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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