基于级配方程的粗粒料压实特性试验研究

Experimental study of compaction characteristics of coarse-grained soil based on gradation equation

级配显著影响着堆石料的压实特性,定量表述级配对堆石料压实特性的影响至关重要。基于连续级配土的级配方程,设计了16组不同级配的试验粗粒料,进行了表面振动压实试验和侧限压缩试验,定量研究了级配对粗粒料压实特性的影响。研究表明:由表面振动压实(动应力)试验和侧限压缩(静应力)试验得到的干密度与级配曲线面积之间均呈二次函数关系,且干密度中的最大值对应的级配曲线面积均在0.9附近;无论是表面振动压实试验还是侧限压缩试验,堆石料都存在干密度最优(最大)的级配。依据试验成果,给出了所试验堆石料的最优级配区间(级配上、下包络线);同时,利用相似级配法论证了实际级配粗粒料的最优级配区间,并根据国内外多座土石坝粗粒料的设计级配验证了该最优级配区间的普遍适用性,为土石坝粗粒料的级配设计提供了理论依据。

Since gradation greatly affects its compaction characteristics,the quantitative description of the effect of gradation on compaction properties is crucial.Based on the continuous gradation equations of soil,16 groups of experimental coarse-grained soils with different gradations were designed.Surface vibration compaction test and confined compression test were carried out to study the effect of gradation on compaction properties of coarse-grained soil.The results showed that the quadratic function relationship was found between the gradation curve area and dry density obtained by surface vibration compaction(dynamic stress)and confined compression(static stress).Besides,the gradation curve areas corresponding to the maximum values of dry density were close to 0.9.Both in surface vibration compaction test or confined compression test,there was optimal dry density of coarse-grained soil under certain gradation.Based on test results,the optimal gradation interval of coarse-grained soil with better compaction was given(upper and lower envelopes of gradation),which was further demonstrated through similar grading method.Meanwhile,the universal applicability of this optimal gradation interval was verified by the design gradation of coarse-grained soil of several earth-rock dams.This paper can provide the important basis for the grading design of coarse-grained soil for earth-rock dam.