小孔径锚索预应力损失影响因素的试验研究  

Tests on affecting factors for pretension loss of cables with small borehole

作　　者：康红普[1,2] 吴拥政[1,2] 褚晓威[1,2] 鞠文君[1,2] 

机构地区：[1]天地科技股份有限公司开采设计事业部,北京100013 [2]煤炭科学研究总院开采设计研究分院,北京100013

出　　处：《煤炭学报》2011年第8期1245-1251,共7页Journal of China Coal Society

基　　金：国家科技支撑计划资助项目(2008BAB36B07)

摘　　要：针对煤矿小孔径树脂锚固预应力锚索的特点,及锚索预应力损失的研究现状和存在的问题,采用理论分析、实验室与井下试验相结合的方法,研究了小孔径树脂锚固锚索预应力损失机理与规律。重点分析了锚索张拉和锁定过程中的预应力损失,及围岩变形引起的预应力损失。锚固系统导致的预应力损失包括锚口摩擦损失和锁定损失;对于特定锚固体系,存在最优限位距离,22 mm锚索的最优限位距离为11～13 mm;锚索长度、张拉油压、张拉机具、锚具及与机具的匹配性对预应力损失率都有不同程度的影响:一般锚索长度越小,预应力损失越大;限位距离偏小时张拉油压在20～30 MPa范围内,预应力锁定损失率最大,限位距离较适当时预应力锁定损失率随张拉油压的增大而减小。最后,提出保证锚索预应力的技术措施,包括施工前进行试验,得出最优限位距离,并对千斤顶进行改造;在锚索预应力设计时,应考虑一定比例的超张拉;当围岩松软破碎时,应增加托板、组合构件及护网的面积、强度与刚度。In view of the features of the pretension cables anchored by resin capsules with small borehole in coal mines,and the research situation and existing questions in the filed of cable pretension loss,the mechanism and laws of pretension loss for cables with small borehole were studied by means of theoretical analysis,laboratory and underground tests.The pretension loss caused by anchor system and deformation of surrounding rock was emphatically analyzed.The pretension loss caused by anchor system includes friction loss and unloading loss;there is an optimal limit distance for one anchor system,11~13 mm is suitable for the cables with diameter of 22 mm.The cable length,tension oil pressure,tension machines,barrel and wedge anchors and their matching with tension machines have different influences on the pretension loss ratio：in general,the shorter the cables,the larger the pretension loss ratio,the cable tensioned by the jacks with smaller limit distance have the largest pretension unloading loss ratio under the pressure of 20~30 MPa,and the unloading pretension loss ratio of the cables tensioned by the jacks with appropriate limit distance is getting smaller with the higher tensioned oil pressure.Finally,several technical measures ensuring cable pretension were put forward,including tests before construction,determining the optimal limit distance,and modifying the jack;taking certain ultra tension into account in cable bolting design;applying the plates,combined beams and steel meshes with larger area,strength and stiffness in soft and broken surrounding rock.

关 键 词：锚索 预应力损失 影响因素 试验 

分 类 号：TD353.6[矿业工程—矿井建设]