CD-method construction method for improving loess tunnel with super-large cross section

Abstract

The invention relates to a CD-method construction method for improving a loess tunnel with a super-large cross section. The method comprises the following steps: (1) excavating an anterior top pilot tunnel, constructing a primary support and a temporary support, and excavating an arch center space; (2) after the excavation depth of the anterior top pilot tunnel reaches 10m, excavating a subsequent top pilot tunnel, and excavating the arch center space; (3) excavating an anterior bottom pilot tunnel, and excavating the arch center space; reserving a soil-column soil body in the temporary support, and meanwhile backfilling the finished anterior bottom pilot tunnel with the excavated soil and carrying out back pressing; (4) excavating a subsequent bottom pilot tunnel, and excavating the arch center space; reserving the soil-column soil body in the temporary support, and meanwhile backfilling the finished subsequent bottom pilot tunnel with the excavated soil and carrying out back pressing; (5) dismantling the temporary support, excavating soil columns in the temporary support, fully excavating a central ditch and an inverted arch, and enabling the inverted arch to form a ring in one time; constructing a secondary lining inverted arch and filling, and then constructing secondary lining. The method has the advantages that large machinery can simultaneously reach the working faces of the top and bottom pilot tunnels and realizes non-interference during construction, the construction progress is fast, and the cost is low.

Description

technical field [0001] The invention relates to the technical field of tunnel construction, in particular to an improved CD method construction method for super-large-section loess tunnels. Background technique [0002] Tunnel excavation is the key control process of tunnel construction. In China, Q3 loess is the main loess, with a natural moisture content of 5-12%. The traditional CD method is used for the construction of ultra-large-section loess tunnels with a buried depth greater than 20m. The excavation sequence of the traditional CD method is to excavate the pilot pit first, then excavate the pilot pit first, then excavate the pilot pit first, then proceed to the pilot pit after the third excavation, and then go down the pilot pit after the fourth excavation. The excavation method is as follows: The following disadvantages: when the lower pilot pit is excavated and supported, large machinery cannot reach the upper pilot pit, the upper pilot pit is mainly constructed by...

AI Technical Summary

Problems solved by technology

The excavation sequence of the traditional CD method is to excavate the pilot pit first, then excavate the pilot pit first, then excavate the pilot pit first, then proceed to the pilot pit after the third excavation, and then go down the pilot pit after the fourth excavation. The excavation method is as follows: The following disadvantages: when the lower pilot pit is excavated and supported, large machinery cannot reach the upper pilot pit, the upper pilot pit is mainly constructed by manual excavation, the construction efficiency is low, and the construction progress is slow; the splicing speed of the temporary support of the upper and lower pilot pits is slow , the process is complex, after the splicing is completed, the slenderness ratio of the temporary support is large, and the stability of the temporary support is poor; there are many temporary supports, a large amount of demolition, the overall progress is slow, and the construction period is long

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