煤渣改良土路基的动弹性模量及临界动应力试验研究

Experimental Study on Dynamic Elastic Modulus and Critical Dynamic Stress of Cinder Improved Soil Subgrade

为研究煤渣改良土作为路基填料在中低围压下的动力特性,以煤渣改良土作为研究对象,利用GDS动态三轴试验系统对不同围压及不同频率下煤渣改良土的动弹性模量以及临界动应力进行了室内试验研究。分析了不同围压及不同加载频率对煤渣改良土动弹性模量的影响,并据此建立了动弹性模量的衰减模型。根据临界动应力的不确定性,利用结构元方法,建立了煤渣改良土临界动应力的模糊线性回归模型。试验结果表明,煤渣改良土的动弹性模量随着加载次数的增加呈负指数关系下降;动弹性模量随围压的增加而逐渐增加,二者大致呈线性关系;动弹性模量随频率的增大而逐渐减小,当加载频率大于3 Hz后动弹性模量的下降速率有所减缓。所建立的衰减模型能够较好地反映出频率及围压对动弹性模量带来的影响。煤渣改良土的临界动应力与加载的频率呈负相关关系,低频的荷载对临界动应力的影响较大;临界动应力与围压之间表现出正相关关系。利用结构元方法所构建的模糊线性回归模型能够较好地反映临界动应力与频率及围压之间的关系,模型精度较高,可以为道路工程中的建设及其临界动应力的确定提供参考。

In order to study the dynamic characteristics of cinder improved soil as subgrade filler under medium and low confining pressure,taking cinder improved soil as the research object,the dynamic elasticity modulus and critical dynamic stress of improved soil under different confining pressures and frequencies are studied by laboratory experiment using GDS dynamic triaxial test system. The attenuation model of dynamic elastic modulus is established based on the analysis of the influence of different confining pressures and loading frequencies on the dynamic modulus. According to the uncertainty of the critical dynamic stress,a fuzzy linear regression model of critical dynamic stress of cinder improved soil is established by structural element method. The experiment result shows that（ 1） the dynamic elastic modulus of cinder improved soil decreases exponentially with the increase of loading times;（ 2） the dynamic modulus increases gradually with the increase of confining pressure,showing roughly linear relationship;（ 3） the dynamic modulus decreases gradually with the increase of frequency,the decline rate of dynamic modulus decreases when the loading frequency is more than 3 Hz,and the attenuation model can better reflect the influence of frequency andconfining pressure on the dynamic elasticity modulus;（ 4） the critical dynamic stress of cinder improved soil is negatively correlated with loading frequency,the low-frequency loads have a great influence on the critical dynamic stress;（ 5） there is a positive correlation between the critical dynamic stress and the confining pressure. The established fuzzy linear regression model based on the structural element method can better reflect the relationship among critical dynamic stress,frequency and confining pressure. It has higher accuracy and can provide a reference for the construction of road engineering and determination of critical dynamic stress.