锚杆间距对岩石群锚基础抗拔力影响的试验研究

EXPERIMENTAL RESEARCH ON EFFECT OF BOLT SPACING ON UPLIFT RESISTANCE FOR GROUP ANCHOR FOUNDATION IN ROCKS

锚杆间距是山区输电线路岩石群锚基础设计的关键参数,甚至直接决定了山区斜坡地形岩石锚杆基础应用的可行性。通过在4种典型岩石地基中对4种不同材质锚杆群锚和单锚基础抗拔对比试验,得到了不同岩石条件、锚筋材质、锚筋直径和钻孔直径下岩石单锚和群锚基础抗拔荷载-位移曲线。通过引入群锚效应系数,量化分析了锚杆间距对岩石群锚基础抗拔承载性能的影响规律,并给出了设计取值建议。结果表明：岩石群锚基础抗拔承载性能既取决于单锚承载性能,也受岩石地基性质影响。工程设计中岩石群锚基础的锚杆间距宜为3~4倍的钻孔直径,相应的群锚效应系数可根据岩石性质不同取0.8~1.0。

Anchor bolt space is the key parameter to the design for anchor foundations in rocks. To some extent,anchor bolt space determines the feasibility of rock anchor foundations on sloping ground in mountainous area. A comparative test for group anchor foundations and single auchor foundation in rocks was carried out in four typical rock subgrade with four kinds of anchor bolt material. The uplift load-displacement behaviours for group anchor foundations and single anchor foundation were analyzed according to different rock conditions,bolt materials,bolt diameters and borehole diameters. The group anchor effect coefficient was used to estimate the bearing capacity for group anchor foundations in rocks. The value of anchor bolt spacing was suggested. It indicated that the bearing capacity of a group anchor foundation was determined not only by bearing capacity of single bolt but also the properties of rock. The anchor bolt spacing of a group anchor should be 3 to 4 times the diameter of borehole and the corresponding group anchor effect coefficients could be recommended within a range from 0. 8 to 1. 0.