无砟轨道路基聚氨酯碎石联结层力学性质研究

以高速铁路无砟轨道基床聚氨酯胶凝级配碎石联结层为研究对象,针对致密性聚氨酯级配碎石混合料的级配、强度、回弹模量开展试验研究。结果表明:聚氨酯级配碎石的毛体积密度随聚氨酯掺量的增加先增加后减少,而其孔隙率随着聚氨酯的掺量增加逐渐减少,当聚氨酯掺量为8%时,聚氨酯胶凝级配碎石能够达到不透水孔隙率1%～3%的控制指标;另外,随着聚氨酯胶水掺量的增加,混合料的强度和回弹模量得到提高,当达到8%的胶水掺量时,混合料强度和回弹模量趋于稳定,随着温度的增加,混合料的强度和回弹模量下降,且在不同的温度区间敏感度不同,但是远大于同等温度下的沥青混凝土强度;浸水48 h后,混合料强度下降,当掺量达到8%时,强度和回弹模量基本不变,且在不同温度区间下降趋势不同,抗压强度在低温(-30～0℃)和高温(60～80℃)变化幅度较小,而回弹模量在常温下(0～60℃)变化较小。

Study on Mechanical Properties of Polyurethane Gravel Joint Layer of Ballastless Track Subgrade

This article takes the high-speed railway ballastless bed-based polyurethane gel-graded aggregates as the research object. An experimental study is conducted on the gradation,strength,and rebound modulus of dense polyurethane graded aggregates. The results show that with the increase of polyurethane content, the bulk density of polyurethane grade aggregates increases first and then decreases,but its porosity gradually decreases. The gelatinized polyurethane graded crushed stone can meet the control index of 1% ～ 3% of the impermeable porosity when the polyurethane content is 8%; and with the increase of the content of polyurethane glue,the strength and rebound modulus of the mixture are improved. When the content of glue is 8%,the strength and rebound modulus of the mixture tend to be stable. With the increase of temperature the strength and rebound modulus of the mixture decrease with different sensitivity in different temperature range,but much higher than those of the asphalt concrete at the same temperature. After 48 hours of immersion,the strength of the mixture decreases. When the content reaches 8%,the strength and rebound modulus of the mixture are basically the same,and the downtrend differs in different temperature range. The compressive strength at low temperature(-30 ～0 ℃) and high temperature(60 ～ 80 ℃) changes slightly,and the rebound modulus at room temperature(0～60 ℃) changes less.