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Rock anchor’s allocation along wall surface or foundation pit side wall should be designed to bear soil pressure. So, after confirmation of soil pressure’s distribution and single rock anchor’s tension, allocation and amount of rock anchor can be designed.

When considering distance among rock anchors, large-diameter anchor bolts should not be less than 3 meters and small-diameter anchor bolts should not be less than 1 meter. If it needs over-crowded design, group effect should be considered.

Rock anchor’s length includes effective anchorage section and non-anchorage section. The length of effective anchorage section should be designed depending on the stratum’s property and ultimate load; the length of non-anchorage section should be designed according to actual distance between structure and stable stratum.

In anchor hole of integrated hard stratum, rock anchor’s stress transfers no more than 2 meters. The main factors influencing ultimate load is slurry’s bonding stress.

In stratum of soft rock and soil, the numerical value of ultimate load has influenced by several factors: stratum’s property, buried depth, underground water, method of grouting, etc. So, tensile test should be carried out before construction, then according to previous method or relative information, estimating its effective anchorage section length. Finally, anchorage length should be revised basing on ultimate pulling capacity of field pull-out test.