级配碎石变形特性的试验

Test of deformation characteristics of graded aggregates

针对级配组成、水的质量分数及密实度等3个因素对级配碎石的影响,采用精密非粘结材料分析仪(precision unbound materials analyzer,PUMA)试验和重复荷载加州承载比(California bearing ratio,CBR)试验方法,研究了级配碎石的抗变形能力.借助累积塑性变形和弹性形变指标,对比分析2种试验异同点.试验结果表明:在荷载作用前期,级配碎石材料抗变形能力受荷载作用的影响显著,随着荷载作用次数不断增大,其影响逐渐减小;PUMA试验与重复荷载CBR试验累积塑性变形结果基本一致,而弹性应变指标存在差异;PUMA试验中弹性应变受级配碎石材料上述3个因素共同影响,重复荷载CBR试验中弹性应变受级配碎石密实度的影响;对级配碎石变形特性精度要求较低时,可选择重复荷载CBR试验研究级配碎石材料变形特性;由于PUMA设备和加载均接近实际工况,因此对级配碎石变形特性精度要求较高时,推荐选用PUMA试验测试方法.

The effects of three factors of gradation composition,water mass fraction and compactness were investigated by precision unbound materials analyzer(PUMA)test and California bearing ratio(CBR)test method with repeated loading.The deformation resistance of graded aggregates was investigated by cumulative plastic deformation and elastic deformation tests,and the similarities and differences between the two tests were compared and analyzed.The results show that the deformation resistance of the graded aggregates is significantly influenced by the load in the early stage of loading,and the influence is gradually decreased with the increasing number of loadings.The cumulative plastic deformation results of the PUMA test are basically consistent with those of the repeated loading CBR test,while the elastic strain indexes are different.The elastic strain in the PUMA test is influenced by the combination of the above three factors of the graded aggregates,while the elastic strain in the repeated loading CBR test is only influenced by the compactness of graded aggregates.If the requirements for the accuracy of deformation characteristics of graded aggregates are low,the repeated load CBR test can be chosen to study the deformation characteristics of graded aggregates.Since the PUMA equipment and loading are close to the actual working conditions,the PUMA test method is chosen when the requirements for the accuracy of deformation characteristics of graded aggregates are high.