深部软岩巷道高预应力增阻大变形锚杆研究及工程应用

Research and engineering application of high pre-stressed resistance enhancement large deformation bolt in deep soft rock roadway

为解决深部软岩巷道大变形、返修率高等问题,在前人研究基础上研发了一种新型高预应力增阻大变形锚杆,该新型锚杆主要由托盘、夹片、杆体1、杆体2、连接套、锥形套、滑移套管等组成,可以施加不低于120 kN的高预应力,让压点可控为180～240 kN,变形量可在150～1 000 mm内灵活调节,锚杆的破断力可达到350 kN左右,且在变形的过程当中能保持较高的渐增支护阻力;室内静力拉伸特性试验结果表明,该新型锚杆与传统锚杆相比,具有"先抗后让再抗,防断增阻"的优良特性;为进一步研究新型锚杆的力学支护机理,在建立该锚杆杆体轴向力学特性曲线的基础上,采用Fish语言编程对FLAC3D数值模拟软件CABLE单元进行了相应二次开发,数值试验获得的试验结果与室内试验结果基本完全一致,高精度模拟了大变形锚杆的轴向拉伸力学行为;典型深部大变形软岩巷道-金阳煤矿-500 m疏水巷变形机制研究表明,围岩强度低、地应力高以及锚杆初始预应力低是导致其变形的主要因素,采用传统等强螺纹钢锚杆支护已经无法解决三者之间的突出矛盾,必须设法加强支护强度降低围岩的变形速率,同时提高支护构件适应围岩大变形的能力,才能保持巷道围岩的稳定;为验证该新型锚杆的支护效果,提出了以该新型高预应力增阻大变形锚杆为核心的新"锚网喷"支护技术,数值模拟及现场监测结果表明,该支护方案可有效提高锚杆受力状态,降低围岩变形量,与原支护方案相比,围岩最终变形量减少了近60%,取得了良好的支护效果,具有重要的推广应用价值。

In order to overcome the support problem of large deformation and the high repairing rate of deep soft rock roadway,a new type of high pre-stressed increase-resistance large deformation bolt is developed based on previous studies.It is mainly composed of pallet,metal clip,rod body 1,rod body 2,connection sleeve,cone-thimble and sliding sleeve.Initial pre-stress applied on the new bolt can reach 120 kN,the let-point-pressure can be controlled to 180-240 kN,the deformation can be adjusted flexibly within 150-1 000 mm.In the process of deformation,it can maintain a high level of increasing support resistance. Static tensile tests in laboratory show that compared with the traditional bolt,the new bolt has excellent characteristics of 'first to support,then let the pressure,the last continue to support,prevent the fracture and increase the resistance'. In order to further study the mechanical support mechanism of the new bolt,the CABLE unit of FLAC3 D numerical simulation software is secondarily developed by using Fish language programming,and the axial tensile mechanical behavior of large deformation bolt is simulated with high precision.Research on the deformation mechanism of a typical deep large deformation soft rock roadway-500 m hydrophobic roadway at Jinyang coal mine in China shows that the low strength of surrounding rock,high ground stress and low initial pre-stress of bolt are the main factors leading to its deformation.It has been unable to solve the outstanding contradiction among the three by using the traditional bolt support. In order to maintain the stability of roadway surrounding rock,it is necessary to strengthen the support strength for reducing the deformation rate of surrounding rock and improving the ability of supporting members to adapt to the large deformation of surrounding rock.To verify the support effect of new bolt,a new 'bolt-mesh-spurting'support technology with the core of new high pre-stressed increase-resistance large deformation bolt is proposed,according to the deformation characteristics and mechanism of surrounding rock in typical deep soft rock roadway of-500 m water discharging gateway in Jinyang coal mine. Numerical simulation and field monitoring results show that the new supporting scheme can effectively improve the stress state of bolt and reduce the deformation of surrounding rock,the final deformation of surrounding rock decreases by nearly 60% compared with the original support scheme.