Excavation method of large-diameter cylindrical tailrace surge chamber

Abstract

The invention relates to an excavation method of a large-diameter cylindrical tailrace surge chamber and belongs to the technical field of water conservancy and hydropower underground engineering construction. The excavation method adopts the technical scheme that firstly, middle drift penetrating and reserved protection layer stage excavation are performed, partitioning penetrating is conducted from inside to outside, and thin-layer excavation and layer-by-layer supporting are adopted; stage adjustment and releasing of surrounding rock stress are achieved, and stress drastic adjustment aftersurrounding rock excavation decompression caused by deep-hole-bench large-charge blasting is avoided; fork segment tailwater pipes adopt pre-stressed anchor cable reinforced supporting and first-stageside wall and vault concrete pouring which are are combined, and the two adjacent tailwater pipes adopt the comprehensive excavation construction scheme of drift vertical excavation and layer-by-layer supporting, and the carrying capacity of a bottom fork reserved rock partition wall is remarkably improved. Since the two adjacent tailwater pipes adopt the comprehensive excavation construction scheme of drift vertical excavation and layer-by-layer supporting, the problems that the surrounding rock stress state after practical engineering construction excavation is implemented is complex, driftintersection positions have stress concentration and large plastic zones, and the construction technical difficulty is high are solved.

Description

technical field [0001] The invention belongs to the technical field of water conservancy and hydropower underground engineering construction, and in particular relates to an excavation method for a large-diameter cylindrical tailwater surge chamber. Background technique [0002] In order to improve the operating conditions and power supply quality of hydroelectric generating units when the load changes, the underground water diversion power generation system project is usually equipped with a tailwater surge chamber. The bottom of the tailwater surge chamber is connected to the upstream draft pipe and the downstream tailwater tunnel respectively. connected. The excavation construction of water conservancy and hydropower underground projects adopts the construction plan of full-section excavation or layered and partitioned excavation according to the design section excavation size, surrounding rock geological conditions and construction conditions. [0003] At present, in pr...

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Problems solved by technology

[0004] In order to overcome the problems existing in the background technology, the present invention proposes an excavation method for a large-diameter cylindrical tailwater surge chamber, which adopts a pilot tunnel to penetrate first, and reserves a protective layer for excavation in stages, and penetrates in sections from the inside to the outside , the excavation plan of thin-layer excavation and layer-by-layer support; the draft tube of the fork section adopts prestressed anchor cables to strengthen the support and pour the first-stage "capped" concrete, and the two adjacent draft tubes are excavated by skipping holes and followed by The comprehensive excavation construction plan of layer support is used to solve the problems of complex stress state of surrounding rock after excavation in actual engineering construction, stress concentration and large plastic zone at the junction of caverns, and high technical difficulty in construction

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