设同步碎石下封层的基面间剪切强度影响因素分析

Analysis of Factors Affecting the Shear Strength Between Surfaces Which is Put up Synchronous Under-seal

旨在考察设同步碎石下封层的基面间剪切强度的影响因素及影响规律，变化沥青种类和用量、碎石粒径和撒布率成型复合试件，采用直剪仪测试不同温度及试验荷载下的剪切强度。研究结果表明：层间剪切强度随沥青用量呈先增加后减小的变化趋势，峰值处为最佳沥青用量；在碎石粒径与撒布率相同的情况下，不同种类沥青的最佳沥青用量及最大抗剪强度有差异，抗剪强度最大的为SBS改性沥青，抗剪强度最小的为基质沥青；碎石撒布率对层间剪切强度有明显的影响，5～10mm、10-15mm碎石的最佳撒布率为60％和30％；碎石粒径对剪切强度和沥青用量有重大影响，推荐5～10mm粒径的碎石作为同步碎石下封层的最佳粒径；随着试验温度升高，层间剪切强度降低；随着试验试件上正压力的加大，层间剪切强度增强，试验结果偏离实际情况，因此推荐合理试验温度为60℃、试验时试件上正压力为0MPa。

To investigate the factors and rule influencing the surface shear strength which is put up synchronous under-seal, changing the type and the amount of asphalt, grain size and spreading rate of composite specimens, we used the direct shear strength test at different temperatures and different test loads. The results show that interlayer shearing strength increases first and then decreases with the increasing asphalt content, and peak is the optimum asphalt content. With the same grain size and spreading rate, optimum asphalt content and the maximum shear strength are different for different types of asphalt, the maxi- mum is the SBS modified asphalt,and the smallest is the matrix asphalt. Gallet spreading rate has obvious effect on the interlayer shearing strength,the optimum spreading rates of grain size 5-10 mm,10-15 mm are 60% and 30%; gallet grain size has a significant impact on shear strength and asphalt content,and we recommended grain size 5-10 mm of synchronous under-seal as the best particle size. The shearing strength decreases with the increase of the test temperature;with the increase of the positive pressure of piece, the shearing strength enhances,and the results deviate from the actual situation. Thus we recommend a reasona- ble test temperature is 60 ℃, and test positive pressure is 0 MPa.