抗大变形麻花锚杆力学特性试验及数值模拟研究

Experimental study on mechanical properties and numerical simulation of large deformation resistant twisted bolt

针对传统锚杆支护出现剪切断裂或无法适应围岩大变形,发明一种新型抗大变形麻花锚杆,并通过室内和数值模拟锚杆拉伸试验,研究螺旋圈数、缠绕间距等结构参数对麻花锚杆力学特性的影响。研究结果表明:相比传统的荷载集中型锚杆,麻花锚杆屈服强度随圈数的增加而出现一定程度的降低,但在屈服之前麻花锚杆产生显著的结构变形,此阶段锚杆拉伸位移较大;螺旋圈数对锚杆拉伸伸长率影响较大,螺旋圈数越多,锚杆破坏时伸长量越大,对于单根麻花锚杆,单根锚杆延伸率从8.325%增大为39.9%,双根锚杆延伸率从26%增大为51%,螺旋圈数与锚杆拉伸位移呈指数关系;锚杆位移随锚杆缠绕间距增大呈线性增加,且随着螺旋圈数的增大,双根麻花锚杆位移增大趋势越明显。工程应用中保证麻花锚杆破断载荷大于锚固力条件下,增大麻花锚杆螺旋圈数和缠绕间距,可有效提高麻花锚杆抗围岩大变形能力,确保巷道支护效果。研究成果可为麻花锚杆的应用和参数设计提供理论基础。

In view of the shear fracture of traditional bolt support or the inability to adapt to the large deformation of surrounding rock,a new type of twist bolt with large deformation resistance was invented.The tensile tests of bolt were carried out through indoor and numerical simulation,and the effects of structural parameters on the mechanical properties of twist bolt were studied such as spiral turns and winding spacing.The results show that compared with the traditional load concentrated bolt,the yield strength of twist bolt decreases to a certain extent with the increase of spiral turns,but the twist bolt has significant structural deformation before yielding,and the tensile displacement of the bolt is large;The spiral turns has a great influence on the tensile elongation of bolt.With the increase of spiral turns,the elongation is greater when the bolt is damaged.For a single twist bolt,the elongation of single bolt increases from 8.325%to 39.9%,and the elongation of double bolt increases from 26%to 51%.The spiral turns has an exponential relationship with the tensile displacement of bolt;The displacement of bolt increases linearly with the increase of bolt winding spacing,and the displacement of double twist bolt become larger with the increase of spiral turns.In engineering application,when the breaking load of twist bolt is greater than the anchoring force,increasing spiral turns and winding spacing of twist bolt can effectively improve the ability of twist bolt to resist large deformation of surrounding rock and ensure the roadway support effect.The research provides a theoretical basis for the application and parameter design of twist bolt.