Construction method of composite soil pressure balance tunnel shielding machine for traversing shallow-buried water-rich sand layer

Abstract

The invention discloses a construction method that a composite soil pressure balanced shield machine passes through a shallow sand layer rich in water, pertaining to the technical field of tunnel construction. When the composite soil pressure balanced shield machine passes through the shallow sand layer rich in water, an injecting system is arranged at the position of a pressure plate and a cutter head of the shield machine so as to inject a matter-a foaming agent, or bentonite, or a macromoleclar polymer, or the mixture of the three, which has the performances of rapid volume expansion and viscosity increase after absorbing water, into the front shallow sand layer rich in water; the shallow sand layer rich in water is rapidly expanded, soil entering an integral pressure cabin is caused to form plastic flow state, and the soil is caused to reach the permeability coefficient of lower than the magnitude of 10<-5>cm/s which is needed by the construction and the caving degree of 10 to 15cm. The technical proposal is scientific and reasonable, simple and easy to implement, can acquire obvious technique effect, adopts the composite soil pressure balanced shield machine for passing through the shallow sand layer rich in water successfully and acquires satisfactory construction quality as well as guarantees the construction period.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a special construction method for a composite earth pressure balance shield machine suitable for construction on a relatively solid rock layer when crossing a shallow buried water-rich sand layer. Background technique [0002] Composite earth pressure balance shield machine is mainly suitable for relatively strong composite strata, and can be constructed in earth pressure balance mode, semi earth pressure mode, and empty warehouse mode. It not only has fast construction speed, but also has low wear on the tool. During the tunnel construction of the applicant on Guangzhou Rail Transit Line 6, 86% of the total length of the tunnel is composed of strongly weathered, moderately weathered and lightly weathered rocks, and it is more reasonable to adopt the composite earth pressure balance mode shield machine. However, there is a 350m-long water-rich sand layer b...

AI Technical Summary

Problems solved by technology

[0004] (1) Due to the high permeability of the silt-fine sand stratum and medium-coarse sand stratum, and the construction section is close to the Pearl River, the groundwater is abundant and the pressure is high, and problems such as gushing are prone to occur during construction, resulting in the rapid disappearance of support pressure, resulting in surface subsidence. Seriously affect ground traffic, buildings and personnel safety;

[0005] (2) If the dregs are not improved properly, they will be compacted under high pressure, and there may be construction failures such as poor soil discharge, blocked soil bins and screw machines

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