GFRP锚杆在锚固工程中握裹力的研究

锚杆作为岩土工程的主要支护材料,广泛应用于边坡、基坑、隧道等工程中。目前在工程中最为常见的锚固技术,是有变形钢筋与水泥砂浆经钻孔注浆而形成。在实际应用中,因钢筋易腐蚀,耐久性差的特点,成为锚固工程中的一大隐患。GFRP锚杆强度高、质量轻、耐腐蚀性强、低松弛等优点,可以替代钢筋作为锚杆应用于锚固工程中。但GFRP筋作为脆性材料,其与水泥砂浆之间的握裹力能否满足要求,将会直接影响到锚固效果。通过对不同锚固深度的GFRP锚杆与水泥砂浆室内拉拔试验,发现握裹力随锚固深度增加而增大,握裹强度随着锚固深度的增加呈现减小的趋势,同时水泥砂浆凝固时间对握裹强度有较大影响,7天初凝时握裹强度仅有28天终凝时的60%左右。通过与同等直径钢筋锚杆与水泥砂浆握裹力对比发现,GFRP锚杆与水泥砂浆握裹力能够达到钢筋锚杆的要求。

Study on the bond stress of GFRP bolt in Anchorage Engineering

As important supporting materials in the geotechnical engineering, anchors are widely used in projects of slope, tunnel and foundation pit. At present the most common anchorage technology is based on drilling grouting for deformed bar and cement mortar. While it is a significant hidden trouble due to the disadvantages such as susceptibility to corrosion and poor durability. GFRP bolt has high strength, light quality, corrosion resistance and low relaxation, hence it can replace rebar in anchorage engineering. However, whether the bond stress between GFRP and cement mortar could meet the requirements will directly influent the anchoring effect considering its brittleness. We set a series of indoor drawing tests on GFRP and cement mortar at different anchoring depth. The results show that the bond stress is larger as the anchoring depth increases and the bond strength reveals the opposite performance. The coagulation time of cement mortar also has a strong effect on the bond strength, the bond strength at initial set accounts for only 60% of that of final set. Contrast to the performance of rebar in same diameter, we find the bond stress between GFRP and cement mortar could meet the requirements.