摘要
及时对锚杆施加较大的预紧力是提高锚杆支护系统刚度的有效途径,为明确预紧力对层状顶板锚杆支护效用的影响及机理,利用FLAC3D的interface单元建立了层状顶板巷道模型,使用pile单元构建仿真锚杆,可模拟锚杆拉、剪、弯、破断、脱锚等力学行为,并实现了预紧力施加。以锚杆预紧力为单一变量,进行了原岩应力作用下不同预紧力锚杆支护效果及机理对比分析。研究表明:随着锚杆预紧力的提高,支护系统的刚度大幅提升,高预紧力锚杆提供的主动约束力不仅可限制结构弱面的张开,还能增大结构面的抗剪强度,抑制结构面活动。主要表征为:一是围岩浅部离层随着预紧力的提高逐步得到控制;二是锚杆最终轴向力与预紧力相比上升幅度逐渐下降;三是锚杆剪切载荷随着预紧力上升逐渐下降。锚杆预紧力较低时,巷道浅部围岩出现大面积拉应力区,失去自承能力;随着锚杆预紧力的提高,围岩拉应力区逐渐减小,浅部围岩处于0~0.5 MPa压应力作用下,支护应力场范围内围岩的不连续变形得到有效控制,浅部围岩实现自稳,同时能有效支撑深部岩体。
It is an effective way to improve the stiffness of bolts support by imposing high pretensioned stress.To clarify the impact of pretensioned stress on bolts support effectiveness for a stratified roof,the roadway model with a stratified roof is established by using the interface element of FLAC3D,and the simulated bolts are constructed with the pile element,which can simulate the mechanical behaviors of bolts such as tension,shear,bending,breaking and anchorage lose.The pretension imposing method was also put forward for the pile element.Taking the pretensioned stress as a single variable,the effectiveness of bolts support with different pretensioned stress under the condition of in-situ stress were evaluated.The research shows that with the increase of pretensioned stress,the stiffness of the rock bolt support system increases greatly.High pretensioned stress can not only limit the opening of weak discontinuities,but also increase the shear strength of the discontinuities and inhibit their movement.The main characteristics are as follows:First,the shallow separation of surrounding rock is gradually controlled with the increase of pretensioned stress;The second is that the rising range of the final axial force of rock bolt gradually decreases compared with the pretensioned stress;Third,the shear load of bolts decreases gradually with the increase of pretensioned stress.With low pretensioned stress,a large area of tensile stress zone appears in the shallow surrounding rock,which loses its self-supporting capacity.With the increase of pretensioned stress,the tensile stress area of surrounding rock gradually decreases,the discontinuous deformation of surrounding rock within the support stress field is effectively controlled.The shallow surrounding rock achieves self-stability,and can effectively support the deep rock mass.
作者
王子越
姜鹏飞
孟宪志
张占涛
WANG Ziyue;JIANG Pengfei;MENG Xianzhi;ZHANG Zhantao(CCTEG Coal Minging Research Institute Co.,Ltd.,Beijing 100013,China;Coal Mining and Designing Department,Tiandi Science and Technology Co.,Ltd.,Beijing 100013,China;Coal Mining Branch,China Coal Research Institute,Beijing 100013,China;State Key Laboratory of Coal Mining and Clean Utilization,China Coal Research Institute,Beijing 100013,China)
出处
《采矿与岩层控制工程学报》
北大核心
2022年第4期52-62,共11页
Journal of Mining and Strata Control Engineering
基金
国家自然科学基金面上资助项目(51774186)。
关键词
预紧力
支护刚度
围岩变形
锚杆受力
锚杆变形
数值模拟
pretensioned stress
support stiffness
surrounding rock deformation
force of bolts
bolt deformation
numerical simulation
