Prestressed anchor cable has been widely used as a main reinforcement measure in geotechnical engineering．But the existing calculation method is difficult to reflect the actual situation

such as slip deformation among rock

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steel stranded wires. Damage softening concept is introduced by studying characteristics of interface. Damage softening constitutive detailed finite element method is presented to simulate prestressed anchor

and a field test result is compared with calculation result. The most remarkable feature of the algorithm is that it can describe stranded wire

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interfaces and other detailed structures. It also can simulate the process of damage softening for interface. The new model can exactly reflect the mechanical change process of the anchoring segment. The test and simulation results are both show that with the load continuous increasing

the interface shear stress peak value of the anchoring segment transfers from the port to inside. The peak value appears at the port when the port is in elastic stage

and the peak value transfers from the port to inside when the port is in damage softening stage. The change law of stress for the anchoring segment of calculation results is basically in accordance with test.