垃圾电厂飞灰改性水泥土三轴试验研究

Tri-Axis Test of Refuse Power Plant Fly Ash Modified Cement-Soil

为研究垃圾飞灰改性水泥土的抗剪强度,提出将垃圾飞灰作为外掺料应用到水泥土的改性研究中。将粒径≤2 mm的黏土颗粒按照不同配比与水泥、飞灰配置成不同飞灰掺量的水泥土试样,采用室内GDS三轴固结排水的试验方法,研究水泥掺量在10%、飞灰掺入比在0%~20%、水泥土在养护龄期为7 d、14 d、28 d时的三轴抗剪强度特性。试验研究发现:1)垃圾飞灰掺入比为5%~10%时,抗剪强度提高最快,且在10%时达到极大值;垃圾飞灰水泥土的应力-应变曲线呈应变软化型,由剪缩向剪胀状态过渡;2)由脆性指标I B可知,飞灰掺量在5%左右时,水泥土整体的稳定性较好;3)内聚力c和内摩擦角φ都随飞灰掺量的增加而增加,其中飞灰掺量10%时,内聚力c达到极大值,飞灰掺量15%时,内摩擦角φ达到极大值;4)采用非线性回归方程(φ=ax ^3+bx ^2+cx+d)拟合内摩擦角与飞灰掺量的关系,从结果上看,采用此回归方程的相关系数高。本研究成果可供路基路面及软基处理参考。

In order to study the shear strength of refuse fly ash modified cement soil,it is proposed to apply refuse fly ash as external admixture to the modification research of cement soil.The clay granules with particle size less than or equal to 2mm are arranged in different proportions with cement and refuse fly ash to form cement soil samples with different refuse fly ash content.The triaxial consolidation drainage test method of indoor GDS was used to study the triaxial shear strength characteristics of cement-soil at the curing age of 7,14 and 28 days when the cement content is 10%and the refuse fly ash content is 0%-20%.The experimental study found that:1)When the ratio of refuse fly ash to cement soil is from 5%to 10%,the shear strength increases the fastest and reaches the maximum at 10%.The stress-strain curve of refuse fly ash-cement soil shows strain softening,which is excessive from shear shrinkage to shear dilatancy;2)According to the brittleness index I B,the overall stability of cement-soil is better when the refuse fly ash content is about 5%;3)The cohesive force c and internal friction angle increase with the increase of refuse fly ash content.The cohesive force c reaches the maximum(when refuse fly ash content is 10%)and the internal friction angle_reaches the maximum(when refuse fly ash content is 15%);4)The non-linear regression equation(φ=ax^ 3+bx ^2+cx+d)is used to fit the relationship between internal friction angle and ash content.From the results,the correlated coefficient of the regression equation is high.The research results can provide reference for the research and analysis of roadbed,pavement and soft foundation treatment.