黏土作为道路工程建设中常用的路基填料,其强度特性对道路的安全稳定服役至关重要.然而,在路基现场填筑过程中,重塑含水率的精准控制存在难度,导致填料的微观结构和强度特性出现变化.旨在探究不同重塑含水率下黏土路基填料的无侧限抗压强度(unconfined compression strength,UCS)的变化规律.为此,对7种不同重塑含水率(14％、16％、18％、20％、25％、28％、30％)的黏土路基填料进行了 UCS试验,并采用扫描电镜(scanning electron microscope,SEM)对典型试样的表观形貌进行了观测.结果表明:1)在不同重塑含水率下,黏土路基填料的应力-应变关系均呈现出应变软化特征,为典型的脆性破坏形式,且该脆性特性随重塑含水率的增加和加载应变速率的增大愈发明显.2)黏土路基填料的UCS随重塑含水率的增加呈现先增大后减小的"钟型"变化规律,曲线峰值点处可定义特征重塑含水率 w-cha=19％,w-cha值小于最优含水率(wopt=28％),该变化规律与黏土团粒和基质吸力的变化相关.3)当重塑含水率在w-cha=19％附近变化(±1％)时,UCS基本保持不变;当重塑含水率在较宽范围内(超出±1％)变化时,在w-cha干侧,UCS变化率随重塑含水率的减小而增大,而在w-cha湿侧,UCS变化率随重塑含水率的增加而增大.研究结果为理解黏土路基填料在不同重塑含水率条件下的工程行为提供了科学依据.
Unconfined Compression Strength of Clay Subgrade Fillings with Different Reshaped Water Contents
As the commonly used roadbed filling materials in road engineering construction,clay's strength charac-teristics are crucial for the safe and stable service of roads.However,during the on-site filling process of the roadbed,precise control of the reshaped moisture content is difficult,resulting in changes in the microstructure and strength characteristics of the filling material.The study is to explore the variation of unconfined compression strength(UCS)of clay subgrade fillers with different remolded moisture contents.UCS tests were conducted on sev-en types of clay subgrade fillers with 7 different reshaped moisture contents(14％,16％,18％,20％,25％,28％,30％).And the apparent morphology of typical samples was observed using scanning electron microscopy(SEM).The results show that:l)With different remolding moisture contents,the stress-strain relationship of clay subgrade filling materials exhibit strain softening characteristics,which is a typical brittle failure form,and becomes more pronounced with the increase of remolding moisture content and loading strain rate.2)UCS of clay subgrade filling shows a"bell shaped"variation pattern,which show firstly increasing and then decreasing with the increase of re-shaped moisture content.The characteristic reshaped moisture content w-cha=19％can be defined at the peak point of the curve,and the w-cha value is lower than the optimal moisture content(wopt=28％).This variation pattern is related to the changes in clay particles and matrix suction.3)When the reshaped moisture content changes around w-cha=19％(±1％),UCS remains basically unchanged;When the reshaped moisture content varies within a wide range(beyond±1％),the UCS change rate increases with the decrease of reshaped moisture content on the w-cha dry side.On the w-cha wet side,UCS change rate increases with the increase of reshaped moisture content.The research results provide a scientific basis for understanding the engineering behavior of clay subgrade fillers under different reshaped moisture content conditions.
unsaturated soilsclaysubgrade fillingsreshaped water contentunconfined compression strengthmicrostructure
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