摘要
分级加载的变形稳定标准是影响K_(30)试验准确性和效率的关键因素。对粉质黏土在最佳含水率下,开展了三组压实系数K分别为0.90、0.95和1.00的小型平板载荷试验,得到不同荷载作用下填土变形时程曲线,分析了分级加载下填土变形的时间效应程度,讨论了不同变形稳定标准对K_(30)值的准确性和试验效率的影响。研究表明:根据"最后1min变形比(1%)"和"变形速率Δs(mm/min)"两种变形稳定标准,K_(30)试验的分级加载时间随时间效应程度分别呈先增长后缩短和加速增长的变化趋势,后者更符合土变形稳定时间与时间效应程度的正相关变化规律;Δs取0.01能降低51%~58%的试验时间,试验误差在6%以内,Δs增大会使试验误差大幅提高,Δs减小则会使试验时间大幅增加;据此,提出了适用于细粒土压实质量检测的级数-时间分级加载控制法。所得成果可为提高细粒土压实质量检测效率提供试验依据。
Deformation stability criterion in stepped loading is the key factor affecting the accuracy and efficiency of K30 experiment.Small plate loading experiment was carried out for three groups of silty clay specimen which have the optimum water content but different compaction coefficients（K） of 0.90,0.95 and 1.00,respectively.The time-history curve of soil deformation under different loads was obtained;the time effect of soil deformation under stepped loading was analyzed;the effect of different deformation stability criterions on the accuracy of K30 values and the efficiency of experiment was discussed.Experimental results indicate that according to two kinds of deformation stability criterions,namely＂deformation ratio in the final 1 minute is no more than 1%＂ and ＂deformation rate（Δs（mm/min））＂,the stepped loading time in K30 experiment presents two different variation trends along with time：one is first increasing and then decreasing,and the other one is accelerated increasing;the latter is more in line with the positive correlation between stability time and time effect of soil deformation.WhenΔsis taken as 0.01 mm,the experimental time can be reduced 51%58%,and experimental error is less than 6%.Along with the increasing ofΔs,experimental error greatly increases,while along with the decreasing ofΔs,experimental time greatly increases.Based on above results,a steps-time stepped loading control method is proposed for the detection of fine grained soil compaction quality.Above-mentioned results may provide an experimental basis for improving the detection efficiency of fine grained soil compaction quality.
作者
熊勇
罗强
张良
蒋良潍
朱江江
XIONG Yong LUO Qiang ZHANG Liang JIANG Liang-wei ZHU Jiang-jiang(School of Civil Engineering in Southwest Jiaotong University, MOE Key Laboratory of High-speed Railway Engineering, Chengdu 610031, China)
出处
《实验力学》
CSCD
北大核心
2017年第3期414-422,共9页
Journal of Experimental Mechanics
基金
国家973计划课题(No.2013CB036204)
国家自然科学基金青年基金项目(51408491)
关键词
铁路路基
K30试验
变形稳定标准
分级加载控制
细粒土
railway subgrade
K30 test
deformation stability criterion
stepped loading control
fine grained soil
