煤样的尺寸、形状及锚固效应

The Size,Shape and Bolting Effects of Coal Specimens

为研究煤样的尺寸、形状及锚固效应,加工了不同高度的圆形、正方形和长方形截面试样,对完整试样单轴抗压强度与高径比关系、锚固试样的强度和变形参数变化进行了试验研究,并通过数值模拟研究了钻孔存在、载荷分布及载荷大小对煤样强度的影响。结果表明,三种截面试样强度均随高径比增大而降低,与高径比呈负指数关系。无托盘非预应力锚杆若不能对试样破裂位置形成闭锁路径,则不能明显提高试样的承载能力。钻孔的存在可明显降低试样的峰值强度及弹性模量,托盘载荷可明显提高试样的残余强度,钢带载荷可明显提高试样的强度和变形参数。相同等效面力作用下,两侧面施加全侧面载荷试样及局部施加托盘载荷试样强度随等效面力增加而增大的程度有限,甚至在等效载荷较高时有所降低。研究结果对进一步理解试样的尺寸、形状及锚固效应有一定帮助。

Different-height coal specimens with circular,square and rectangular cross section were prepared for studying its size,shape and bolting effects. Then,relationship between uniaxial compressive strength and height-diameter ratio and the change of strength and deformation parameters of bolted coal specimens were experimentally studied,and the effects of existence of borehole,the distribution and amount of load to strength of coal specimens were studied through numerical simulation. The strength of intact coal specimens with above three cross sections decreases with height-diameter ratio,and has a negative exponent relation with height-diameter ratio. Non-prestressed bolt with no tray can not improve the strength of coal specimens if they can not form a latching path for spreading position of specimens fracture. Existence of borehole can obviously lower the peak strength and elastic modulus of coal specimens,the tray-load can increase the peak strength and elastic modulus to a certain extent and the residual strength obviously of coal specimens,and the load of steel strip can obviously improve all above three parameters of the coal specimens. The increase of the strength of the coal specimens with two opposite sides free and full section load on other two opposite sides is limited and even decreases when the equivalent surface load is high enough. Above research results have certain help to further understand the size,shape and bolting effects of coal specimens.