Large-section loess tunnel supporting system and supporting construction method

Abstract

The invention discloses a large-section loess tunnel supporting system and a supporting construction method. The large-section loess tunnel supporting system comprises a tunnel forepoling structure, atunnel initial supporting structure and a tunnel secondary lining. The upper surface of an inverted arch secondary lining in the tunnel secondary lining is a horizontal plane, and an inverted arch backfill layer is arranged on the horizontal plane. The supporting construction method comprises the following steps of firstly digging a tunnel and conducting initial supporting; and secondly constructing the secondary lining and backfilling the inverted arch. The large-section loess tunnel supporting system is reasonable in design, easy and convenient to construct, high in construction efficiencyand good in use effect, the tunnel forepoling structure, the tunnel initial supporting structure and the tunnel secondary lining constitute a combined supporting system to stably and reliably supportthe large-section loess tunnel, the upper surface of the inverted arch of the secondary lining is adjusted to be a horizontal plane, the construction process of the inverted arch of the tunnel can beeffectively simplified, and the rigidity of the inverted arch of the tunnel is greatly improved; in this way, the construction efficiency of the tunnel secondary lining is improved, the ring sealingtime of the tunnel secondary lining is shortened, the integrity of the tunnel secondary lining is higher, and the overall force bearing effect is better.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, in particular to a large-section loess tunnel support system and a support construction method. Background technique [0002] Loess refers to wind-moved deposits of yellow silt during the Quaternary period in geological time. Loess collapsibility coefficient (also called collapsibility coefficient) is a mechanical parameter to evaluate the collapsibility of loess. Under a certain pressure, loess collapsibility coefficient refers to the ratio of the height difference before and after soaking of soil samples to the original height of soil samples. The collapsibility coefficient of loess is an important index to evaluate the collapsibility of loess, which can be directly measured by experiment. According to the different collapsibility coefficient of loess, loess can be divided into collapsible loess and non-collapsible loess. Among them, non-collapsible loess refers to loess that does...

AI Technical Summary

Problems solved by technology

Nowadays, in the construction process of deep-buried loess tunnels at home and abroad, due to the soft and porous loess soil, the development of vertical joints, and the creep effect, especially in water-rich sections, the surrounding rocks are prone to enlarged deformation after being exposed for too long after excavation. There are problems such as difficult deformation control and restricted construction progress

When using the traditional three-step method, three-step temporary inverted arch method, three-step large arch foot temporary inverted arch method, double-side wall pilot pit method, CD method and other excavation construction methods, there are three problems as follows: First, the inverted arch is not closed in time to form a ring, the deformation of the surrounding rock is large, and collapse accidents are prone to occur; second, the space section is divided, and the narrow working space is not conducive to large-scale mechanical construction, cannot meet the needs of large-scale mechanized construction, and interferes with each process Larger, the work faces cannot be operated synchronously, the efficiency is low, and the construction speed is slow; third, the temporary inverted arch is used, the project cost is high, and there is a large safety risk in the demolition process

Moreover, when using the three-step method to excavate a large-section loess tunnel, since the excavation section is divided into many sections, the section of the large-section tunnel is divided into several small sections (sections) for construction, and it needs to be erected and dismantled during the excavation construction. A large number of temporary supports, many construction procedures, high technical requirements for the connection of various small-section support structures, difficult support, and low construction efficiency

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