内锚头预制长度对锚索锚固效果的影响规律OA

To investigate the influence laws of precast inner anchorage head length in mountain-area railway slop anchoring cables on the anchoring performance,laboratory tests and numerical simulation are adopted to analyze the effects of precast inner anchorage head length on the axial stress distribution of anchor cable grout,the stress distribution at the interface between grout and borehole wall,and the ultimate bearing capacity of precast anchorage heads.The results indicate that under identical stratum conditions,extending the precast length of the inner anchorage head can enhance the bearing capacity of the anchor cable with limited overall improvement.The optimal improvement in bearing capacity is achieved when the precast length of the inner anchorage head reaches 50 cm.Precasting the inner anchorage head with high-strength cement grout can effectively optimize the load-bearing mechanism of anchor cables.It transforms the concentrated load borne by conventional bearing plates into a combined resistance provided by the bond strength between the precast anchorage head and borehole wall and the normal stress of grout at the anchorage head tail,thus improving the ultimate bearing capacity of anchor cables.As the precast length of the inner anchorage head increases,the maximum compressive strain at the contact surface between the tail of the precast inner anchorage head and surrounding grout gradually decreases.The precast inner anchorage head can significantly reduce the maximum compressive strain,and the reduction is the greatest as the precast inner anchorage head length increases from 25 cm to 50 cm.With an increase in precast inner anchorage head length,the displacement of the anchorage head decreases,the shear slip zone at the interface between grout and borehole wall shortens,the peak values of shear stress and normal stress drop while their distribution range expands.Meanwhile,the yielding range of grout in front of the precast inner anchorage head shrinks,the internal shear yielding area expands with a lower yielding degree,and stress concentration is mitigated,which optimizes the stress state of the anchoring system with precast inner anchorage heads.The research findings can provide technical support for the design of anchor cables with precast inner anchorage heads.