The Anchorage Design in the Hydropower Station—Indirect Analogy of Self Drilling Anchor Bolt


The indirect analogy was applied widely in the three underground chambers in Hydropower Station. Though it can not explained clearly in theory that how the self drilling anchor bolt and the shotcrete work to support the underground structure, it is not argued the success was achieved in practice.

Sinorock self drilling anchor bolt is a reliable and convenient anchoring system which is applied in complicated geological conditions for rock support work. It is particularly applied in the following geological conditions, such as weathered rock, gravel layer, backfill, hard conglomerate, etc. The self drilling anchor bolt is unique anchoring system and fulfills current and increasing demands of the tunneling industry and ground engineering for safer and faster production. The self drilling anchor bolt system provides advantages for all areas of its applications, where boreholes would require the time consuming drilling with casing systems in unconsolidated or cohesive soil.

The supporting parameters designed for indirect analogy of self drilling anchor bolt are as follows:

Specification name Surrounding rocks category Span (m) Shotcrete thickness (cm) Self Drilling Rock Bolt
Dia. (mm) Length (m)
The technical specification of anchor bolt and shotcrete >Ⅱ 15~20 12~15 2.5~3.5
>Ⅱ 20~25 15~20 3.0~4.0
The design specification of workshop >Ⅱ 16~20 12~15 18~22 2.5~3.5
>Ⅱ 21~25 15~20 15~20 3.5~5.0

In the construction process applying the indirect analogy of self drilling anchor bolt, the following requirements should be met:

1) The self drilling anchor bolts should be arranged radially and evenly on the cross-section diagram. The arrangement will look like rectangle or rhombus on the engineering plan.

2) Relating to the direction of the self drilling anchor bolts, they should be perpendicular to the outlines of the tunnel in the whole rock strata while perpendicular to the surface of the rock in the bedded rock so as to the self drilling anchor bolt can function well.

3) The depth of the self drilling anchor bolt eyelet should be consistent with the construction requirement and the anchor bolt used in the project.
4) The rock grains, broken pieces and water should be blown out of the self drilling anchor bolt eyelet to ensure the anchorage quality.

To ensure that reliable anchorage effect of the self drilling anchor bolt. Generally speaking, the anchorage length is only about 200m which has good resistance capacity. The self drilling anchor bolt will has practical anchorage power when the plate is clung to the the rock surface and the nut is tightened

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