摘要
The cemented-gangue-fly-ash backfill(CGFB)prepared from coal-based solid waste materials commonly exhibits high brittleness,leading to an increased susceptibility to cracking.Uniaxial compressive strength(UCS),acoustic emission(AE),and scanning electron microscopy tests were conducted on CGFB samples with recycled steel fiber(RSF)contents of 0,0.5%,1.0%and 1.5%to assess the mechanical properties and damage evolution law of the CGFB.The research findings indicate that:1)When RSF contents were 0.5%,1%,and 1.5%,respectively,compared to samples without RSF,the UCS decreased by 3.86%,6.76%,and 15.59%,while toughness increased by 69%,98%,and 123%;2)The addition of RSFs reduced the post-peak stress energy activity and increased the fluctuations in the b-value;3)As the RSF dosage increased from 0 to 1.5%,the per unit dissipated strain energy increased from 5.84 to 21.51,and the post-peak released energy increased from 15.07 to 33.76,indicating that the external energy required for the CGFB sample to fail increased;4)The hydration products,such as C-S-H gel,ettringite,and micro-particle materials,were embedded in the damaged areas of the RSFs,increasing the frictional force at the interface between the RSF and CGFB matrix.The shape variability of the RSFs caused interlocking between the RSFs and the matrix.Both mechanisms strengthened the bridging effect of the RSFs in the CGFB,thereby improving the damage resistance capability of CGFB.The excellent damage resistance occurred at an RSF content of 0.5%;thus,this content is recommended for engineering applications.
采用煤基固废材料制备的胶结矸石-粉煤灰充填体(CGFB)普遍存在脆性高、易开裂的问题。为揭示不同掺量再生钢纤维(RSF)改性CGFB的力学性能和损伤演化规律,对RSF掺量为0、0.5%、1.0%、1.5%的CGFB试样进行了单轴抗压强度、声发射和扫描电镜试验。研究结果表明:1)RSF掺量为0.5%、1.0%和1.5%时,与未掺RSF的试样相比,单轴抗压强度分别降低了3.86%、6.76%和15.59%,但是韧性分别增加了69%、98%和123%;2)RSF的掺入降低了峰值应力后的能量活跃性,增加了b值变化频率;3)随着RSF掺量从0增加至1.5%,单元耗散应变能从5.84逐渐增加至21.51,峰后释放能从15.07逐渐增加至33.76,表明CGFB试样发生破坏失稳需要的外界能量逐渐增加;4)C-S-H凝胶、钙矾石等水化产物和微颗粒材料嵌入RSF的结构损伤处,提高了RSF与CGFB基体界面的摩擦力;RSF的形状变异性,使得RSF与基体之间形成机械咬合力;二者均增强了RSF在CGFB内部的桥接效应,因此CGFB的抗损伤能力得以提高。当RSF掺量为0.5%时,改性CGFB便具有较好的抗损伤能力,可作为工程应用时的充填材料配比。
基金
Projects(52274143,51874284)supported by the National Natural Science Foundation of China。
作者简介
Corresponding author:CAO Sheng-gen,PhD,Professor,E-mail:caoshenggencumt@163.com,ORCID:https://orcid.org/0000-0002-6861-2316。
