GFRP锚杆加固顺层岩质边坡的机制研究

摘要

由于传统钢筋锚杆存在易腐蚀、耐久性差等缺点,GFRP(玻璃纤维增强复合材料)锚杆得到了高度重视.然而,GFRP锚杆的弹性模量小且抗剪强度低,故其加固顺层岩质边坡的机制仍需进一步研究.考虑顺层岩质边坡的顺层滑移破坏模式,基于Winkler假定和锚杆荷载传递机理对边坡岩体与锚杆的相互作用机制进行理论分析,建立剪切位移作用下锚杆的力学模型,并对其进行验证.基于此,结合GFRP锚杆的物理力学参数(如弹性模量、抗剪强度等),考虑坡体剪切位移、锚杆与潜在滑面夹角及岩体无侧限抗压强度等影响因素,分析GFRP锚杆加固顺层岩质边坡的机制.结果表明:1)当锚杆与潜在滑面夹角为45°时,硬岩中坡体较小的剪切位移导致GFRP锚杆发生剪切屈服;软岩中坡体产生较大的剪切位移时,GFRP锚杆发生受拉屈服.2)当锚杆屈服时, GFRP锚杆在加固不同抗压强度的岩体时提供的抗力差异较大,加固软岩时抗力最大;随着岩体无侧限抗压强度增大,GFRP锚杆提供的抗力逐渐变小;相比而言,钢筋锚杆在加固不同抗压强度的岩体时提供的抗力大小基本接近.3)硬岩中,锚杆与潜在滑面夹角对GFRP锚杆抗力的影响较大,夹角越小,抗力越大;软岩中,锚杆与潜在滑面夹角对GFRP锚杆抗力的影响较小;当夹角为5°~60°时,GFRP锚杆均能提供较大抗力.研究结果为岩质边坡锚固研究及工程应用提供参考.%High attention had been drawn to the new anchor bolt materials represented by glass fiber reinforced polymer (GFRP) as the traditional steel anchor bolt show certain disadvantages,including low corrosion resistance and poor durability.However,due to the shortcoming of the GFRP anchor bolt,including relatively low shear strength and elastic modulus,the mechanism of the GFRP anchor bolt to strengthen rock bedded slope need to be further studied.The interaction mechanism between rock mass and anchor bolt was analyzed based on the Winkler's assumption and the loading transfer mechanism.Then the mechanical model of anchor bolt under the action of shear displacement was established and verified.On this basis,by considering some influence factors,such as shear displacement,the angle between the anchor bolt and potential sliding surface and uncon-fined compressive strength of rock mass,the mechanisms of the GFRP anchor bolt for strengthening rock bedded slope were studied.It is con-cluded that:1) when the angle between the anchor bolt and the sliding surface was 45°,the GFRP anchor bolt generated shear yield because of a small shear displacement in hard rock,and the GFRP anchor bolt presented tensile yield in soft rock.2) when the anchor bolt yielded,the differ-ences between the resistances of the GFRP anchor bolt for reinforcing different rocks are obvious.The greater the unconfined compressive strength of rock mass is,the smaller the resistance of the GFRP anchor bolt is.In contrast,the differences between the resistances of the steel an-chor bolt for different rocks are slight.3) In hard rock,the angle between the anchor bolt and the sliding surface had a great impact on the resist-ance of anchor bolt.The smaller the angle is,the greater the resistance is.In soft rock,the angle between the anchor bolt and the sliding surface had a small impact on the resistance of GFRP anchor bolt.The GFRP bolt can provide greater resistance for the angle from 5° to 60°.These results can provide some references for anchoring of rock slope and related engineering applications.