城市固体垃圾炉渣的三轴试验研究

Triaxial Tests on Municipal Solid Waste Incineration Bottom Ash

炉渣是城市固体垃圾焚烧后的产物,可以代替骨料作为路基垫层材料使用,实现资源的二次利用。为了研究炉渣在路基填筑过程中的强度以及变形特征,对干密度ρ_d分别为1.4, 1.5, 1.6 g/cm^3、龄期t分别为3, 7, 14, 28 d的饱和炉渣试样进行不同围压下的三轴固结排水试验,通过Lambe平面方法确定炉渣的抗剪强度参数(黏聚力、内摩擦角)。研究结果表明:在低围压下(100,200 kPa),城市固体垃圾炉渣的应力-应变曲线呈现应变软化特性;随着围压增大硬化特征明显,在高围压下(200,400 kPa)呈现应变硬化特性;炉渣的峰值强度与龄期增加呈现对数关系,即随着时间增长,强度逐渐增加,在早期阶段(14 d以前)强度增长迅速,随后增长速率减缓;黏聚力和内摩擦角随着龄期增加呈现不同的变化趋势,黏聚力随着龄期增加而不断变大,且近似呈现线性增长,而内摩擦角基本保持不变。研究成果可为炉渣的二次利用提供参考。

As the product of municipal solid waste incineration(MSWI), bottom ash can be used as subgrade cushion material by replacing aggregate to achieve the secondary utilization of resources. To investigate its shear strength and deformation properties, triaxial consolidated drained tests were performed on saturated bottom ash with different dry density(ρd=1.4, 1.5, 1.6 g?cm-3) at different curing ages(t=3, 7, 14, 28 d). Shear strength parameters(cohesion and internal friction angle) of MSWI bottom ash are determined via Lambe plane approach. Results unveil that the stress-strain curve of MSWI bottom ash under low confining pressure(100 kPa and 200 kPa) displays strain softening characteristic, and hardening feature under higher confining pressure(200 kPa and 400 kPa). Peak shear strength increases logarithmically with curing age, namely peak shear strength grows rapidly in the early stage(before the first 14 days), and in subsequence slows down. Cohesion and internal friction angle present different trends with curing age: cohesion increases with curing age, while internal friction angle remains almost unchanged.