泡沫轻质土的疲劳性能及工程应用研究

Fatigue Performance of Foamed Lightweight Soil and Its Application

为研究泡沫轻质土的疲劳性能,预测泡沫轻质土路基在行车荷载作用下的疲劳寿命,在前期实验基础上,依托广佛江快速通道江门段一标段工程,采用UTM-100伺服液压多功能材料实验系统对泡沫轻质土进行四点弯曲小梁疲劳实验;基于疲劳实验结果,运用威布尔分布和对数正态分布建立S-N疲劳方程。研究结果表明:泡沫轻质土的疲劳寿命受应力比的影响较为显著,随应力比的增大呈逐渐减少趋势;尽管泡沫轻质土的疲劳寿命离散性较大,但其对数值与应力比或应力比对数值均呈现出良好的线性关系;泡沫轻质土的疲劳寿命虽然具有较大的离散性,但其对数疲劳寿命与应力比或对数应力比均呈现出良好的线性关系;验证了泡沫轻质土的疲劳寿命既服从威布尔分布又服从对数正态分布,但更宜采用威布尔分布进行分析;通过工程实例的论证,提出了泡沫轻质土路基在行车荷载作用下实际疲劳寿命的预测方法,预测结果说明泡沫轻质土用作公路路基填料具有良好的抗疲劳性能,该项研究不仅为行车荷载作用下泡沫轻质土路基疲劳性能评估提供理论依据,而且为其他类似工程应用提供技术支撑。

In order to study fatigue performance of foamed lightweight soil and forecast its fatigue life under vehicle load in the supporting project named the first segment of Guangzhou-Foshan-Jiangmen Freeway in Jiangmen city, on the base of preliminary tests, four-point flexure beam fatigue tests on foamed lightweight soil was conducted by using UTM-100 test system. Based on the fatigue test results, using Weibull distribution and lognormal distribution, S-N fatigue equations of foamed lightweight soil were obtained. The results show that the stress ratio has a prominent effect on fatigue life of foamed lightweight soil, its fatigue life will decrease gradually with the increase in stress ratio. Besides, the fatigue life also has large discreteness, but the linear relation between logarithmic fatigue life and stress ratio appears good. In addition, it has been proved that the fatigue life not only obeys Weibull distribution but also obeys lognormal distribution, and Weibull distribution can analyze its fatigue life better. Through an engineering case, a method is proposed for predicting the actual fatigue life of foamed lightweight soil subgrade under the traffic load, the results show that foamed lightweight soil as subgrade filler has good anti-fatigue performance, which can provide the theoretical basis for the assessment of fatigue performance of foamed lightweight soil under vehicle load, and references to other similar projects.