A Method for Improving Flow Plasticity of Earth Pressure Shield Slag Adapted to Sand and Pebble Stratum

Abstract

The invention discloses a soil pressure shield waste soil flow plasticity improvement method suitable for a sandy cobble stratum. The soil pressure shield waste soil flow plasticity improvement methodincludes the following steps that S1, according to a geological investigation report, the content of sandy cobble stratum fine particles in the total mass of the stratum is determined as the actual fine particle content; S2, the critical fine particle content is determined by a sandy cobble fluidity model; S3, according to the actual fine particle content and the critical fine particle content, the type of an improver is determined; and S4, the mixing amount of the improver is determined according to the actual fine particle content, wherein the fine particles in the S1, the S2 and the S3 refer to particles with the particle size less than 2 mm. According to the method, the sandy cobble stratum with the characteristic of 'three highs' has the good fluidity, cutter torque of a shield tunneling machine is lowered, cutter pasting is avoided, the viscosity of waste soil is lowered, the stability of the tunnel face is maintained, earthwork overexcavation is controlled, surface collapse andstagnant discharge or flowing are prevented, and the excavation efficiency is improved.

Description

technical field [0001] The invention belongs to the technical field of improving dregs in earth pressure shield tunneling, and in particular relates to a method for improving flow plasticity of dregs in earth pressure shields suitable for sand and pebble formations. Background technique [0002] The tunnel body of the interval shield tunnel mainly passes through the Q3fgl+al high-strength pebble soil sandwiched with lens sand layer. The tunnel body is basically located in the pebble soil layer. It is grade IV. The overlying cohesive soil is mostly plastic, and the part of the sandwiched sandy soil is a liquefied soil layer with a slight liquefaction level; the pebble soil has poor sorting and uniformity, high compressive strength, poor self-stability, large permeability coefficient, and poor water permeability. Strong, good water richness. The groundwater level along the line varies greatly with the seasons, and it is mainly pore water existing in sandy soil and pebble soi...

AI Technical Summary

Problems solved by technology

For the construction of the sand and pebble formation with the characteristics of "high water-rich, high pebble content, and high pebble strength", the problems encountered in the construction of the sand and pebble stratum are: first, the frequent tool change operations caused by the serious wear of the shield cutter head and the tool; The ground subsidence caused by the half-cabin operation of the shield pressure chamber occurs frequently; the third is the spewing at the outlet of the spiral earthmover and the stagnant discharge of the muck in the pressure chamber caused by the improper improvement of the muck in the pressure chamber

[0004] Analyzing the cause of the faults in the earth pressure shield excavation of the sand and pebble formation above, the main reason is that it is difficult to improve the sand and pebble slag into flow-plastic slag. Because of the difficulty of sand and pebble improvement, the pressure chamber slag must be discharged in time during excavation, otherwise it will be easy. Accumulation of high-strength dregs forms serious stagnant discharge; and rapid discharge will inevitably lead to obvious over-excavation during shield excavation. When the over-excavation reaches a certain level, surface collapse will be inevitable.

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