路基砾类填料土动力特性影响因素试验分析

Experimental Analysis on Influencing Factors of Dynamic Characteristics of Subgrade Gravel Packing Soil

动应力-动应变关系作为反映路基填料土动力特性的重要参数,对其进行影响因素试验研究可为路基填料土的工程特性研究提供参考依据。本文借助动三轴试验手段进行砾类土动应力-动应变关系影响因素研究,采用应力控制的加载方式进行加载,分析了试验压力、土样含水率、土样压实度、荷载作用频率和初始静偏应力等5种条件和砾类土动力特性的作用规律,并总结砾类土动应力-动应变关系变化规律。研究结果表明:当动三轴试验的围压为30 kPa、土样压实度为96%、含水率为最佳含水率7.5%时,其动应力-动应变关系曲线接近应力轴,砾类土的动强度大;荷载作用频率为1、2 Hz变化时以及小于10 kPa的初始静偏应力对砾类土的动应力-应变关系影响较小;针对各影响因素下的动应力-动应变关系曲线,对其采用的双曲线模型拟合相关系数均大于0.96,说明该模型能够有效拟合其关系曲线;根据试验模型可知,试验中压力越大,参数a、b值越小,同理,土样的压实度越大,a、b值也越小。

The dynamic stress-dynamic strain relationship is an important parameter reflecting the dynamic characteristics of subgrade filling soil, and the experimental study of its influencing factors can provide a reference for the engineering characteristics of subgrade filling soil. In this paper, the authors use the dynamic triaxial test method to study the influence factors of gravel-like soil, adopt the stress-controlled loading method to load, analyze five conditions such as test pressure, soil sample moisture content, soil sample compressibility, load frequency, and initial static deviatoric stresses of gravel-like soil, and also summarize the dynamic stress-strain relationship change law of gravel-like soil. The research results show that: 1) When the pressure of the dynamic triaxial test is 30 kPa, the compaction of the soil sample is 96%, and the optimal moisture content is 7.5%. The dynamic stress-dynamic strain relationship curve is closer to the stress axis, and the dynamic strength of gravel-like soil is great;2) When the load frequency changes between 1 and 2 Hz, the initial static deviator stress(less than 10 kPa) has little effect on the dynamic stress-strain relationship of gravel-like soil;3)The fitting correlation coefficients of the dynamic stress-dynamic strain relationship curve to the hyperbolic model used are all greater than 0.96, indicating that the model can effectively fit the relationship curve;4) Based on the test model, the greater the pressure in the test, the smaller the values of the parameters a and b;similarly, the greater the compression of the soil sample, the smaller the values of a and b.