考虑颗粒破碎影响的隧道宕渣循环动载累积变形特性试验

Experimental Study on Accumulative Deformation Characteristics of Tunnel Slag Under Cyclic Dynamic Loading Considering Particle Breakage Effect

为促进交通基础设施建设的绿色低碳化,隧道宕渣常作为路基填料资源化利用。通过开展大型循环动载三轴试验和颗粒单轴压缩试验,探讨了长期交通荷载下不同含水率宕渣的力学特性演化规律,并分析了宕渣的颗粒破碎及主要母岩成分颗粒的特征强度特性。循环动载三轴试验结果表明:高含水率使得宕渣材料累积塑性变形及体应变显著增加,回弹模量则明显减小;轴向应变累积速率与循环次数关系曲线具有明显的衰减和稳定阶段,且高含水率试样在加载后期累积速率明显提高。由试验前后试样级配特征曲线对比分析可知,循环加载导致宕渣颗粒破碎明显,且破碎程度随试样含水率增大而提高。宕渣中凝灰岩、砂岩及粉砂质泥岩颗粒的单轴压缩试验结果表明:饱和度提高导致单颗粒特征强度降低,且粉砂质泥岩特征强度降低最明显。基于试验结果,建立了宕渣破碎率和最终累积应变关联的表达式,合理预测了长期交通荷载下宕渣材料颗粒破碎的演化规律。

To support the green and low-carbon construction of transportation infrastructure,tunnel debris is often used as roadbed filling material for resource utilization.By conducting large-scale triaxial cyclic dynamic load tests and particle uniaxial compression tests,the mechanical characteristics evolution law of slag with different moisture content under long-term traffic loading was explored.In addition,the study investigated both the particle breakage of slag and the characteristic strength of its primary rock component particles.The cyclic triaxial test results show that high moisture content significantly increases the cumulative plastic deformation and volumetric strain of the slag material,while the rebound modulus appreciably decreases.The relationship curve between axial strain cumulative rate and cycles number exhibits a distinct attenuation and stabilization stage,with an appreciably increase in the accumulation rate during the later stages of loading for high moisture content samples.Analysis of the particle size distribution curves before and after testing reveals that cyclic loading results in significant breakage of the slag particles,with the degree of breakage increasing with higher sample moisture content.Uniaxial compression tests on particles of tuff,sandstone,and sandy mudstone particles in the slag indicate that increasing saturation leads to a decrease in the characteristic strength of individual particles,with sandy mudstone exhibiting the most significant decrease in characteristic strength.Based on the experimental results,a correlation expression between slag breakage rate and final cumulative strain was established,allowing for the reasonably prediction of the evolutionary patterns of particle breakage in slag materials under long-term traffic loading.