Grouted rock bolts subject to axial loading in the field exhibit various failure modes,among which the most predominant one is the bolt-grout interface failure.Thus,mechanical characterization of the grout is essentia...Grouted rock bolts subject to axial loading in the field exhibit various failure modes,among which the most predominant one is the bolt-grout interface failure.Thus,mechanical characterization of the grout is essential for understanding its performance in ground support.To date,few studies have been conducted to characterize the mechanical behaviour of fiber-reinforced grout(FRG)in rock bolt reinforcement.Here we experimentally studied the mechanical behaviour of FRG under uniaxial compression,indirect tension,and direct shear loading conditions.We also conducted a series of pullout tests of rebar bolt encapsulated with different grouts including conventional cementitious grout and FRG.FRG was developed using 15%silica fume(SF)replacement of cement(by weight)and steel fiber to achieve highstrength and crack-resistance to overcome drawbacks of the conventional grout.Two types of steel fibers including straight and wavy steel fibers were further added to enhance the grout quality.The effect of fiber shape and fiber volume proportion on the grout mechanical properties were examined.Our experimental results showed that the addition of SF and steel fiber by 1.5%fiber volume proportion could lead to the highest compressive,tensile,and shear strengths of the grout.The minimum volume of fiber that could improve the mechanical properties of grout was found at 0.5%.The scanning electron microscopy(SEM)analysis demonstrated that steel fibers act as an excellent bridge to prevent the cracks from propagating at the interfacial region and hence to aid in maintaining the integrity of the cementitious grout.Our laboratory pullout tests further confirmed that FRG could prevent the cylindrical grout annulus from radial crack and hence improve the rebar’s load carrying capacity.Therefore,FRG has a potential to be utilized in civil and mining applications where high-strength and crack-resistance support is required.展开更多
冻土与构筑物基础接触面的本构模型是分析冻土区构筑物与冻土相互作用、评价工程安全稳定性的基础和关键.为了降低切向冻胀力对基础的上拔作用,防止发生冻拔失稳破坏,青海-西藏±400 k V直流联网工程基础广泛采用玻璃钢覆盖基础表面...冻土与构筑物基础接触面的本构模型是分析冻土区构筑物与冻土相互作用、评价工程安全稳定性的基础和关键.为了降低切向冻胀力对基础的上拔作用,防止发生冻拔失稳破坏,青海-西藏±400 k V直流联网工程基础广泛采用玻璃钢覆盖基础表面,以消减冻胀力.为了合理描述玻璃钢与冻土接触面力学特性,采用应变直剪仪开展了青藏冻结粉土与玻璃钢基础接触面直剪试验,获取了不同冻结温度条件下接触面剪应力-位移曲线,分析总结了接触面的强度变化规律和受力变形特性,基于试验得到的接触面本构规律建立了耦合温度效应的冻结粉土与玻璃钢基础接触面剪切应力-位移关系.模型预测结果与试验结果的比较表明,预测结果与试验结果吻合良好,该模型能够较好的描述接触面的力学特性.展开更多
文摘Grouted rock bolts subject to axial loading in the field exhibit various failure modes,among which the most predominant one is the bolt-grout interface failure.Thus,mechanical characterization of the grout is essential for understanding its performance in ground support.To date,few studies have been conducted to characterize the mechanical behaviour of fiber-reinforced grout(FRG)in rock bolt reinforcement.Here we experimentally studied the mechanical behaviour of FRG under uniaxial compression,indirect tension,and direct shear loading conditions.We also conducted a series of pullout tests of rebar bolt encapsulated with different grouts including conventional cementitious grout and FRG.FRG was developed using 15%silica fume(SF)replacement of cement(by weight)and steel fiber to achieve highstrength and crack-resistance to overcome drawbacks of the conventional grout.Two types of steel fibers including straight and wavy steel fibers were further added to enhance the grout quality.The effect of fiber shape and fiber volume proportion on the grout mechanical properties were examined.Our experimental results showed that the addition of SF and steel fiber by 1.5%fiber volume proportion could lead to the highest compressive,tensile,and shear strengths of the grout.The minimum volume of fiber that could improve the mechanical properties of grout was found at 0.5%.The scanning electron microscopy(SEM)analysis demonstrated that steel fibers act as an excellent bridge to prevent the cracks from propagating at the interfacial region and hence to aid in maintaining the integrity of the cementitious grout.Our laboratory pullout tests further confirmed that FRG could prevent the cylindrical grout annulus from radial crack and hence improve the rebar’s load carrying capacity.Therefore,FRG has a potential to be utilized in civil and mining applications where high-strength and crack-resistance support is required.
文摘冻土与构筑物基础接触面的本构模型是分析冻土区构筑物与冻土相互作用、评价工程安全稳定性的基础和关键.为了降低切向冻胀力对基础的上拔作用,防止发生冻拔失稳破坏,青海-西藏±400 k V直流联网工程基础广泛采用玻璃钢覆盖基础表面,以消减冻胀力.为了合理描述玻璃钢与冻土接触面力学特性,采用应变直剪仪开展了青藏冻结粉土与玻璃钢基础接触面直剪试验,获取了不同冻结温度条件下接触面剪应力-位移曲线,分析总结了接触面的强度变化规律和受力变形特性,基于试验得到的接触面本构规律建立了耦合温度效应的冻结粉土与玻璃钢基础接触面剪切应力-位移关系.模型预测结果与试验结果的比较表明,预测结果与试验结果吻合良好,该模型能够较好的描述接触面的力学特性.
