Red bed sand shale tunnel large deformation section construction method

Abstract

The invention discloses a red bed sand shale tunnel large deformation section construction method to effectively avoid large deformation and collapse during the construction period, lower the construction period delaying risk and improve the construction efficiency. According to the monitoring measurement condition and the deformation condition of the constructed section, the large deformation section is tested, the reserved deformation is enlarged, and the support parameter is adjusted to reinforce preliminary bracing; the rise span ratio of an excavated section is adjusted according to crownsettlement, horizontal displacement and inverted arch deformation condition, and the excavated section of the large deformation section is determined; the rise span ratio is adjusted to be about 0.5;when the horizontal displacement value is larger, the crown settlement value is smaller relative to the horizontal displacement value and inverted arch deformation is not generated, the excavated section of the large deformation section is determined to be semi-circular; and when the crown settlement value, horizontal displacement value and inverted arch deformation upheaval value are larger, theexcavated section of the large deformation section is determined to be circular.

Description

technical field [0001] The invention relates to a tunnel, in particular to a construction method for a large-deformation section of a red-bed sand-mudstone tunnel passing through the mudstone interbedded with sandstone in western Yunnan. Background technique [0002] The Hengduan Mountains in Southwest my country have complex strata and well-developed structures. Among them, the Mesozoic Jurassic Bazhulu Formation mudstone interbedded with sandstone, purplish red, light purplish red, partially gray-white quartz, gypsum, argillaceous structure, and thin-layered structure. The rock mass is extremely broken and extremely poor in stability. The rock mass is breccia-like and soil-like, and the rock layer is smooth. Because it is mainly red, it is commonly known as the "red layer", and its thickness ranges from hundreds of meters to thousands of meters. [0003] The "red layer" is mainly composed of mudstone and fine sandstone. Its special features are: the mudstone is soft, weak ...

AI Technical Summary

Problems solved by technology

[0003] The "red layer" is mainly composed of mudstone and fine sandstone. Its special features are: the mudstone is soft, weak in weathering resistance, easy to soften when exposed to water, and its strength is obviously reduced after contact with water. The bonding force between layers is weakened and the stability becomes poor.

If the "red layer" is opened for a long time, it will lose stability, fall blocks, and collapse severely. Tunnel excavation is prone to accidents such as large deformation, collapse, and even door closing accidents.

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