Rapid-construction method for rapid change of small-section into large-section tunnel

Abstract

The invention relates to a quick construction method that small section is changed to big section in tunnel construction abruptly, characterized in that first of all, small heading on the one side of small section is transited to side heading on the relative side of big section; then by the portrait space formed in side heading of the big section transverse heading is dug on the big section; permanent early support for the big section is constructed in the transverse heading so as to form permanent early closed ring for all section; the whole early support for big section is in the transverse heading; digging and support for big section tunnel is constructed on the front and back ends of the big section in the working plane formed by the transverse heading. The invention is provided with low cost, good safety and simple construction technology so on.

Description

Technical field: [0001] The invention relates to a construction method for tunnels with abrupt cross sections from small to large. Background technique: [0002] As shown in Figure 1, in the construction of subway tunnels, the transition from a standard section with an excavation size of 5.8×6.23m to a large section with a maximum excavation size of 13.950×9.354m is the boundary between the standard section and the crossover tunnel. Use a small pilot pit to construct first, and then reverse expansion after reaching the turnout section. The specific method is to operate according to the following steps: [0003] 1. From the double-arch middle hole (mileage YK15+159), start the temporary small pilot pit construction. [0004] 2. When the small pilot pit is constructed to the B-shaped section (mileage YK15+200), the small pilot pit begins to climb and expand. [0005] 3. After passing through the 14m-long climbing section, the small pilot pit was expanded into a B-shaped sect...

AI Technical Summary

Problems solved by technology

[0008] 1. The climbing of the small pilot pit is long, and the cost of temporary support is high;

[0009] 2. The working surface of the small pilot pit is narrow, which is not conducive to the discharge and feeding of materials, the ventilation is difficult, the construction period is long, and the construction period is difficult to guarantee;

[0010] 3. After the small pilot pit is formed, the reverse expansion construction must break the temporary support, and carry out secondary disturbance to the surrounding rock of the tunnel. The construction risk is high and the safety hazard is relatively large.

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