Abstract: According to the characteristics of prestressed anchor cables in foundation pit, the principles of selecting the locking values of the tensile anchor cable, pressure anchor cable, scattered-load anchor cable and multi-row anchor cable were discussed through the methods of theoretical derivation, analytical calculation, numerical simulation and example validation. Due to the difference in the stiffness of the anchor head, the results show that according to the specification range, the small locking value is adopted for the tensile anchor cable, but the pressure anchor cable requires the large locking value. Scattered-load anchor cables should be tensioned and locked by groups, and the locking value of steel strand in each group is related to the length of the free segment, dispersion distance and displacement of anchor head. The locking value of the segment bearing body increases with the enlargement of the distance away from the orifice. Different locking values are applied for multi-row anchor cables considering the cable tension locking sequence. Based on the difference of the real anchor head displacement after each row anchor cable is locked, the smaller locking value should be adopted for the upper anchor cables, but the larger locking value is for the lower anchor cables. Therefore, the obtained relevant laws can provide useful references for the stretch locking construction of anchor cables in foundation pit.

Key words: foundation pit, prestressed anchor cable, stretch locking value, cable type, anchorage pile