中文摘要：

单元双块式无砟轨道支承层假缝与道床板伸缩缝对齐设置能够有效引导支承层裂缝发展，但伸缩缝位置轨道结构竖向抗弯刚度较小，列车通过时基床应力应变幅值较大，且在多雨潮湿环境中，雨水等杂物易侵入下部基础，破坏结构稳定。针对支承层假缝与道床板伸缩缝对齐设置存在的缺点和不足，对支承层假缝设计进行优化：伸缩缝位置支承层上表层铺设一定长度的土工布，土工布中心线与伸缩缝中心线重合，土工布两侧支承层分别切割深度为支承层厚度1／3的假缝。土工布的铺设使得板端形成一定长度的分层隔离区，通过对不同长度隔离区设计方案在温度、温度梯度或列车荷栽等作用下的响应分析，并结合现场施工经验，发现隔离区长度在800～1000mm或1400—1600mm时结构性能良好。综合考虑，土工布铺设长度选为1720mm。

英文摘要：

The false joint of support layer of the unit double - block ballastless track, which alignes settings with the expansion joint of track concrete layer , can guide the crack＇ s development effectively. But the vertical ben-ding stiffness of track structure near expansion joints is small, thus the stress and strain amplitude of subgrade bed is large while train passes by, and the rain or other debris is easity intrude into the base of the bottom of track so as to the base will suffer destruction in a rain or damp environment. According to the shortcomings and deficiencies of the false joint of support layer of the unit double - block ballastless track alignment set with expan-sion joint of track concrete layer, we need to optimize design about the fale joint, i.e. to cover a certain length of geotextile on the surface of the support layer, and the centerline of geotextile should coincide with expansion joint＇ s centerline, and the support layer on both sides of geotextile cuts false joint respectively, of which the depth is 1/3 of the thickness of the support layer. The covering of geotextile makes the end of plate form a certain length of stratified isolation. Through the analysis of response of the different length of the quarantine area design scheme under the condition of temperature, temperature gradient and train load, combined with on - site con-struction experience, we know that structure performance is good in the condition of the length of stratified isola-tion zone being 800 - 1 000 mm or 1 400 - 1 600 mm. After overall consideration, we recommend that the length of the quarantine area be 1 640 mm.