High-geostress dam foundation excavation construction technology

Abstract

The invention discloses a high-geostress dam foundation excavation construction technology. According to the high-geostress dam foundation excavation construction technology, before the excavation of a dam foundation, a dam foundation protecting layer with slope being smaller than or equal to that of the dam foundation and thickness being 25-40 times diameter of bottom charge of a bench blast hole is reserved; and anchor bars running through the dam foundation protecting layer and the dam foundation are pre-anchored before the dam foundation protecting layer is excavated to form a foundation building surface of a designed dam foundation. By adoption of the high-geostress dam foundation excavation construction technology, uploading relaxation and backfilling deformation, even the phenomena of'crack slip', plate fracturing and local rock bursting caused by high geostress in the excavation of the dam foundation are avoided, therefore secondary excavation resulting from the uploading relaxation and the backfilling deformation of the foundation building surface of the dam foundation can be effectively avoided; and by consolidation grouting and repeated anchoring construction, the construction period and the construction cost are greatly saved and a remarkable economic benefit is obtained.

Description

technical field [0001] The invention belongs to the technical field of water conservancy and hydropower building construction, in particular to the technical field of civil construction in water conservancy and hydropower construction, and particularly relates to a high ground stress dam foundation excavation construction technology. Background technique [0002] In the construction of hydropower stations, the quality of dam foundation excavation is directly related to the stability and safety of the entire project. However, when the dam foundation is excavated in an alpine gorge, the height difference between the two sides is extremely large, and a natural high geostress area is formed at the bottom of the gorge. The foundation surface after excavation has been exposed for a long time. Under the combined factors of stress release and gravity unloading, it is prone to unloading springback and relaxation damage, so that the rock mass cannot meet the requirements of the arch d...

AI Technical Summary

Problems solved by technology

However, when the dam foundation is excavated in an alpine gorge, the height difference between the two sides is extremely large, and a natural high geostress area is formed at the bottom of the gorge. The foundation surface after excavation has been exposed for a long time. Under the action of comprehensive factors such as stress release and gravity unloading, unloading springback and relaxation damage are prone to occur, making the rock mass unable to meet the requirements of the arch dam foundation surface

The traditional construction technology of excavating the dam foundation first and then carrying out anchor bolts, hanging nets, shotcrete and other supports due to the long time interval from excavation to the completion of support, the rock mass of the dam foundation is difficult to function before unloading, resulting in the dam foundation in high ground stress areas. The rock mass rebounded loose and sheared, and rockburst occurred, so large-scale secondary excavation, consolidation grouting and repeated anchor reinforcement construction were necessary, resulting in a delay in the construction period and a substantial increase in construction costs

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