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Tunnel-before-wall-type crossed tunnel portal excavation supporting construction method

A construction method and intersection technology, which are used in earth-moving drilling, wellbore lining, tunnel lining, etc., can solve the problem of the stability of the surrounding rock at the intersection without a systematic solution, avoid backfilling concrete, reduce over-excavation, save construction time and The effect of engineering costs

Active Publication Date: 2019-08-09
POWERCHINA HUADONG ENG COPORATION LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The first excavation method is more commonly used, and there is no systematic solution for the second excavation method to solve the problems of intersection excavation formation and surrounding rock stability

Method used

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  • Tunnel-before-wall-type crossed tunnel portal excavation supporting construction method
  • Tunnel-before-wall-type crossed tunnel portal excavation supporting construction method
  • Tunnel-before-wall-type crossed tunnel portal excavation supporting construction method

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Embodiment Construction

[0015] like figure 1 As shown, the excavation and support construction method of a hole-first and wall-type intersection of the present invention is used for excavation and support of large-scale underground caverns and tunnel intersections. During the excavation of the upper part of the cavern, simultaneously Excavation and support of the lower tunnel 11. exist figure 1 Among them, the reference numeral 21 represents the excavated section of the cavern, and the reference numeral 22 represents the unexcavated section of the cavern.

[0016] After the permanent section 11 of the tunnel is excavated to the designed structural surface of the side wall of the cavern, the reinforced concrete spraying layer 6 and the system anchor rod 53 shall be constructed on the side arch of the tunnel in time to complete the system spraying, anchoring and netting support, and then according to the size of the tunnel section Continue to excavate into the cavern to form a tunnel extension sectio...

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Abstract

The invention provides a tunnel-before-wall-type crossed tunnel portal excavation supporting construction method. A tunnel is excavated before cavern side walls, after system supporting is completed,the tunnel extends into a cavern, temporary supporting is conducted to ensure site construction safety, locked anchor bars and countersunk anchor bars are implemented to protect intersections, pre-splitting holes are formed in the circumferential direction along the cavern side walls for blasting, rock mass, nearby the intersections, inside and outside the cavern side walls is separated, during later excavation of the cavern, the rock mass within the pre-splitting range is mechanically excavated, secondary blasting damage is avoided, and system supporting follows till the intersections are excavated. A scheme for solving the problem of excavation supporting of the large underground cavern intersections is provided for a tunnel-before-wall-type excavation mode, excavation forming of the intersections can be ensured to a great extent, stability of surrounding rock of the tunnel intersections and the cavern high side walls is facilitated, overexcavation is reduced, later backfilling of alarge amount of concrete is avoided, the construction period is shortened, and the engineering cost is saved.

Description

technical field [0001] The invention relates to a construction method for excavating and supporting a cross opening with a hole first and a wall behind, which is suitable for underground engineering fields such as hydropower and water conservancy. Background technique [0002] In modern hydropower and water conservancy projects, the caverns in the underground powerhouse area are huge, and the height of the main powerhouse and tailwater surge chamber is often hundreds of meters. The diversion tunnel, busbar tunnel, and tailwater tunnel intersect with it, and the height generally exceeds 15-20m. And the number is very large, forming a large number of tunnel entrance and exit intersections. These large intersections are subjected to complex forces, coupled with unfavorable factors such as large differences in geological conditions and high ground stress. After excavation, problems such as relaxation and collapse of surrounding rocks are more serious. The excavation is serious a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21D13/02E21D20/00E21D11/10
CPCE21D11/10E21D13/00E21D20/00
Inventor 王鹏石安池李孙权唐鸣发周光辉王敬勇
Owner POWERCHINA HUADONG ENG COPORATION LTD
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