After 7-8 days of grouting and curing of anchor cable in soil layer, when the strength of anchor solid is greater than 15MPa and not less than 75% of the design strength, the surrounding purlin is installed on the supporting structure for prestressed tension after the bearing capacity is confirmed. The tensioning equipment is the same as the prestressed structure, and the prestressed value is 75% - 80% of the designed anchoring force.

Attention should be paid to the following items during tensioning:

Before the formal tensioning of the anchor cable, 10% ～ 20% of the design tensile force should be taken, and the anchor cable should be pre tensioned for 1 ～ 2 times; the formal tensioning of the anchor cable should be loaded in stages, and after each stage of loading, the load should be stable for 3 minutes, and the elongation value should be recorded; the load should be loaded step by step until 80% of the design anchoring force, and the last stage load should be stable for 5 minutes, and the elongation value should be recorded; When there is no obvious attenuation of the prestress of the pull rod, the pull rod can be locked; after the completion of the design tensioning for a period of time, depending on the attenuation of the prestress of the pull rod, individual anchor cables can be appropriately over tensioned.