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- Title
Study on Excavation Face Stability of Shield Tunnel in Sandy Cobble Stratum Considering Slope Angle.
- Authors
HU Ruiqing
- Abstract
With the increasing application of shield tunnels in cities, the types of strata and obstacles that shield tunnels cross are becoming more and more diverse. In order to meet the requirements of shield tunnel operation and crossing complex strata or avoiding important structures, a certain linear slope angle is often used in the linear design of shield tunnels. At present, the research theory on the influence of slope angle on the stability of excavation face of shield tunnel is not comprehensive. In order to study the influence of different slope angles on the stability of excavation face of sandy pebble shield tunnel, this paper is based on a sandy pebble stratum earth pressure shield project. Based on the limit equilibrium theory model, the discrete element numerical simulation is used to analyze the instability mechanism of excavation face of shield tunnel in sandy pebble stratum considering the slope angle of tunnel line. The upper bound solution model of limit analysis is improved by combining the line slope angle, and the existing limit equilibrium method, limit analysis method theoretical solution and numerical simulation results considering the line slope angle are selected for verification. The results show that the ultimate support pressure of excavation face is affected by soil friction, tunnel diameter and soil cohesion. With the increase of tunnel diameter from 3 m to 15 m, the support pressure of tunnel face increases gradually, with the increase of cohesion, the support pressure decreases gradually to 0. Under the same conditions, the support pressure at the pitch angle of 10° is greater than that at the pitch angle of horizontal,-5° and-10°. When considering the slope angle to calculate the limit support pressure of the excavation face, the elevation condition is more unfavorable to the stability of the excavation face than the horizontal condition and the pitch condition. Therefore, in the design stage, designers need to pay special attention to the geological conditions of the stratum through which the shield passes to comprehensively determine the line type to ensure the safety of subsequent construction; when the shield encounters the sand pebble stratum uphill, the construction personnel need to strictly control the soil chamber pressure and the single ring unearthed amount.
- Publication
Railway Standard Design, 2023, Vol 67, Issue 12, p168
- ISSN
1004-2954
- Publication type
Article
- DOI
10.13238/j.issn.1004-2954.202303210006