Test method for earth pressure balance shield muck workability and improvement optimization evaluation

Abstract

The invention provides an earth pressure balance shield muck workability and improvement optimization evaluation test system and method. The test system comprises a horizontally-arranged test cylinder, an axial loading device for simulating a pushing mechanism of the shield tunneling machine, a radial extrusion ring bag for simulating a dumping mechanism of the spiral conveyer, a water supply system for applying different water pressures, a shearing rod for collecting soil sample strength, a test bin pressure sensor for collecting pore water pressure and the like. The test method comprises thestep of comprehensively testing the workability of the soil sample under the simulated working condition of controlling any one of the soil discharge speed and the pushing pressure under different water pressure conditions or controlling the synchronous change of the soil discharge speed and the pushing pressure. The workability test of the soil sample comprises any one or more of permeability, strength and deformation characteristics. Data measured by the test system and the test method are more scientific and objective, certain automatic control intellectualization is achieved, and the testsystem and the test method are particularly suitable for simulating soil pressure balance shield muck workability related test research under special working conditions such as rich water.

Description

technical field [0001] The invention relates to shield tunnel working condition simulation experiment equipment, in particular to an earth pressure balance shield tunnel muck workability and an improvement and optimization evaluation test method. Background technique [0002] In the construction of earth pressure balance shield, the workability of the test chamber dregs has an important influence on the safe and rapid excavation of the shield. In order to achieve the ideal workability, it is usually necessary to improve and optimize different dregs. The workability of slag (including slag before improvement and slag after improvement) mainly includes three aspects: strength, deformation and permeability: specifically, low strength, moderate compression deformation characteristics and low permeability Reduce cutter wear, control mud cake formation, meet the pressure balance of the test chamber and achieve ideal flow plasticity. However, the above three aspects usually cannot...

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Problems solved by technology

[0003] Existing test equipment and test methods for the workability of dregs and improved bodies have some defects in varying degrees: ① The main methods used for strength and deformation characteristics testing are direct shear instrument, triaxial instrument and confining compression instrument, but for For dregs, when a certain amount of improver is added, the flow plasticity is enhanced, and it is difficult to form a plastic sample for the above-mentioned equipment test; The test research on the coarse-grained and wide-graded muck soil samples that frequently appear in structural engineering; ③The existing soil permeability test equipment mainly tests the permeability of dregs under constant or variable head, but for such things as underpassing rivers, seabeds, etc. For water-rich formations such as strata, they usually face high water-rich pressures of hundreds of kilopascals; at the same time, in water-rich formations, there is mutual coupling between the water pressure and soil pressure in the shield machine test chamber, which affects the workability of muck. However, the existing penetration equipment generally cannot exert earth pressure on the muck during the penetration test. The coupling effect between the two is ignored in the test method, and the workability of the obtained muck will also lose certain objectivity; ④Shield tunneling The muck in the soil bin is affected by the multi-field coupling of the cutterhead mechanism, the axial push mechanism, the soil discharge mechanism and the groundwater environment, etc., and its workability is in a dynamic process of random changes. Simplified methods are used to test the workability of slag, and the results obtained have certain limitations in practical engineering applications

Furthermore, the existing tests on the workability of muck soil are mainly based on three separate tests, and it is difficult to obtain the three indicators of strength, deformation and permeability through simultaneous testing, resulting in a sharp increase in the workload of the test experiment and due to the Some experimental errors are caused by the instability of sample preparation

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