含不同充填面倾角的胶结充填体力学特性及破坏模式试验研究

Experimental Study on Mechanical Characteristics and Failure Mode of Cemented Backfill with Different Dip Angles of Backfill Surface

在大规模的采空区充填过程中,受限于充填站的连续造浆能力,多次充填导致充填面处易出现不同的倾角。为探究含不同充填面倾角的胶结充填体(CTB)的力学特性及破坏模式演化过程,制备不同养护龄期下含不同充填面倾角的CTB试件以及完整试件,采用WDW-20电子万能实验机进行单轴压缩试验。结果表明:1)含充填面倾角试件的峰值强度、峰值应变、弹性模量均随着充填面倾角的增加呈现减小的变化趋势,而养护龄期的增加能够有效弱化充填面倾角所带来的结构效应。2)与完整试件相比,含充填面倾角的试件在孔隙压密阶段以及裂纹扩展阶段历时较短。在峰后破坏阶段,均表现出延性破坏特征,但随着养护龄期增加,延性破坏特征逐渐减弱。3)含充填面倾角试件的总能量、弹性应变能、耗散能和能量耗散率均小于完整试件。充填面倾角与总能量之间遵循线性函数关系、而与弹性应变能和耗散能之间遵循二次多项式函数关系。4)充填面倾角显著影响了CTB试件的破坏模式,随着倾角的增加,破坏模式演化过程为充填面处张拉破坏(0°、10°)→垂直充填面处张拉破坏(20°)→充填面处张拉-剪切破坏(30°),研究结论可为存在充填面倾角的充填体强度设计提供一定的理论参考。

In the process of filling a large scale extraction area,the continuous slurry making capacity of the filling station is limited,and multiple fills lead to different dips at the filling face.In order to investigate the mechanical properties and the evolution of the damage mode of the cemented filler(CTB)containing different filling surface inclination,CTB specimens containing different filling surface inclination and complete specimens under different maintenance ages were prepared and tested by uniaxial compression using WDW-20 electronic universal testing machine.The results show that:1)The peak strength,peak strain and modulus of elasticity of specimens with filling surface inclination show a decreasing trend with the increase of filling surface inclination,while the increase of maintenance age can effectively weaken the structural effect brought by filling surface inclination.2)Compared with intact specimens,specimens with filling surface inclination have a shorter duration in the pore compacting phase as well as in the crack extension phase.In the post-peak damage phase,all exhibit ductile damage characteristics,but with the increase in maintenance age,ductile damage characteristics gradually weakened.3)The total energy,elastic strain energy,dissipation energy and energy dissipation rate of specimens with filling surface inclination are smaller than those of intact specimens.The inclination of the filling surface follows a linear function with the total energy and a quadratic polynomial function with the elastic strain energy and dissipation energy.4)The tilting angle of the filling surface significantly affects the damage mode of CTB specimens,with the increase of the tilting angle,the damage mode evolves as follows:tensile damage at the filling surface(0°,10°)→tensile damage at the vertical filling surface(20°)→tensile-shear damage at the filling surface(30°),the findings of the study can provide some theoretical reference for the strength design of the filling body where the tilting angle of the filling surface exists.