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A Determination of adhesion
The bond strength (the bond strength per unit bond area) is related to the surface roughness of the bonded rock. The bond strength is carried out on the device. Firstly, a hole of a certain diameter is drilled on a rock block with a certain geometrical size recovered from the site, and is poured into the mortar round pier , and a drawbar is placed in the hole, and the drawbar has a circular base with the same diameter as the hole , and the measurement is performed. When the nut is tightened with a through-type jack ( tensioning rod and the mortar column is cut out from the hole ) , the ratio of the force indicated by the jack to the surface area of ​​the mortar column and the rock block is the ratio The bond strength of the mortar bonded to the rock.
B Determination of the gripping force The gripping force is a binding force of the core material such as steel wire or steel strand wrapped by the cement mortar. The size of the grip is related to the surface condition of the steel or steel strand, the surface area and the ratio of the cement label to the cement mortar.
Grip force is an integral part of the anchoring force and is an important parameter for designing long anchor cables, which can usually be measured by indoor simulation tests. Take a steel pipe with the same diameter as the actual anchor hole, the length is not less than 0.5m or according to the convenience of the test. The steel mortar or steel strand is united in the steel pipe with the same cement mortar as the actual proportion. After 28 days, the material is in the material. The steel rope is pulled outward from the simulated anchor hole on the test machine, and the force measured at this time is the grip force.
Long anchor cable anchoring force
The anchoring force is related to the diameter of the borehole, the ratio of cement mortar and the thickness of the steel rope or steel strand. The reasonable combination of these factors can be obtained by orthogonal test design or by engineering analogy.
The cohesive force between the cement mortar column and the anchor hole wall is related to the anchor hole diameter and the length of the cement mortar in the anchor hole. The larger the diameter, the larger the perfusion length and the greater the cohesive force.