粉煤灰掺入量对煤矸石水力学性质和导气率的影响

EFFECTS OF FLY ASH INCORPORATION ON HYDRAULIC CHARACTERISTICS AND AIR PERMEABILITY OF COAL GANGUE

为研究粉煤灰掺入量对煤矸石水力学性质和导气率的影响,设计9种矸灰比的粉煤灰-煤矸石混合物,运用室内一维定水头法和压力膜仪(DIK-3423)以及一维瞬态法测试了混合物饱和含水量、饱和导水率、水分特征曲线和导气率等指标,并与土壤、粉煤灰和煤矸石进行对比分析。结果表明:1)粉煤灰的掺入可以提高煤矸石的饱和含水量,矸灰比3∶7~2∶8的混合物的饱和含水量为36.9%~41.4%,数值上最接近土壤;2)混合物的饱和导水率受粉煤灰掺入量和容重影响,相同粉煤灰掺入量下提高容重会降低饱和导水率,而饱和导水率变化的整体趋势随粉煤灰掺入量的增大而减小;3)混合物的持水性能随粉煤灰掺入量的增大而增大;4)混合物的导气率随粉煤灰掺入量的增大而减小,粉煤灰掺入量<40%的混合物导气率对含水量的敏感度呈先减小后增大的趋势,其余比例混合物导气率变化较均匀;5)矸灰比(煤矸石与粉煤灰体积比)在3∶7~2∶8混合物的植物有效水含量为17.3%~17.6%,数值上最接近土壤,选用粉煤灰-煤矸石混合物充填塌陷土地时可控制矸灰比在3∶7,此时渗透性小,且可以保证有良好的土壤有效水供给。研究结果可为塌陷区土地复垦质量的改良提供数据参考。

In order to study the effect of fly ash incorporation on the hydraulic characteristics of coal gangue,nine kinds of mixtures with different mixing ratio of fly ash and coal gangue were analyzed.The indoor one-dimensional fixed head method,a multi-fold pF Meter(DIK-3423)and a falling-pressure method was used to measure the volume of saturated water content,saturated hydraulic conductivity,the soil water characteristic curve(SWCC)and air permeability.The results indicated that:1)adding fly ash could increase the saturated water content of the mixtures,and the saturated water content of the mixture with mixing ratio of 3∶7 was 36.9%~41.4%,the closest to the soil;2)the saturated hydraulic conductivity of the mixture was affected by mixing ratio and bulk density.The saturated hydraulic conductivity decreased with the increase of bulk density,and also with the increase of fly ash’s dosage in general.3)the water retention capability of the mixture decreased with the increase of fly ash dosage.4)the air permeability of the mixture decreased with the increase of fly ash’s dosage.The air permeability of the mixture with fly ash incorporated below 40%had a changing tendency of small to large in sensitivity to water content,and mixture with other composition changed more uniformly.5)the available water content of the mixture with the mixing ratio of 3∶7~2∶8 was 17.3%~17.6%,the closest to the soil;when the mixture was used to fill the collapsed land,the mixing ratio could be controlled at 3∶7 to ensure suitable available water supply while the permeability was at a lower level.This study could provide data reference for improvement of land reclamation model in the subsidence areas.