石窟岩体浅层加固微型木锚杆抗拔力影响因素试验研究

Experimental Study on the Influence of Surface Morphology of Micro-wooden Bolt on Its Pullout Resistance

石窟岩体浅层剥落掉块病害常采用微型木锚杆加固,微型木锚杆在微型钻孔中抗拉力及影响因素研究成果甚少。以松木杆为芯材,以环氧树脂粉煤灰混合浆液为灌浆锚固材料,主要研究微型木锚杆表面形态对其抗拔力影响。根据微型木锚杆直径(10 mm、12 mm)、锚固长度(100 mm、150 mm)和表面形态(表面光滑、磨砂划痕、3 cm加箍、2 cm加箍)的不同,设计了4种类型共计16组微型木锚杆拉拔试验。结果表明:磨砂划痕及2 cm加箍处理微型木锚杆其极限抗拔力为5.7~10.0 kN,破坏界面抗剪强度为1.58~1.99 MPa,较表面光滑木锚杆提高15%~31%;3 cm加箍处理微型木锚杆其极限抗拔力为5.1~9.5 kN,破坏界面抗剪强度为1.45~1.86 MPa,较表面光滑木锚杆提高9%~17%。微型木锚杆直径、锚固长度对界面抗剪强度有一定影响。研究成果可为微型木锚杆治理石窟浅层剥落病害提供设计计算依据。

The micro-wooden bolt is often used to strengthen the shallow spalling of grotto rock mass,yet few research results on the pullout resistance and influencing factors of micro-wooden bolt in micro drilling are reported.Taking pine rod as core material and epoxy resin-fly ash mixed slurry as grouting material,the effects of surface morphology of the micro-wooden bolt on its pullout resistance are studied.According to the different diameter(10 mm,12 mm),anchorage length(100 mm,150 mm)and surface morphology(smooth,scratch,3 cm hoop and 2 cm hoop)of micro-wooden bolts,16 groups of pull-out tests of four types of micro-wooden bolts are designed.The results show that the ultimate pullout force of micro-wood bolt treated with surface scratch or 2 cm hoop is about 5.7~10.0 kN,the interface shear strength is about 1.58~1.99 MPa,which is about 15%~31%higher than that of smooth wooden bolt.The ultimate tensile strength of the 3 cm hooped micro wooden anchor bolt is about 5.1~9.5 kN,and the shear strength of the failure interface is about 1.45~1.86 MPa,which is about 9%~17%higher than that of the smooth surface wooden anchor bolt.The diameter and anchorage length of micro-wooden bolt have a certain influence on the interface shear strength.The research results can provide design and calculation basis for the shallow spalling disease of grottoes strengthened with micro-wooden bolts.