全风化花岗岩改良土高速铁路路基填料的适宜性试验研究

摘要

To study appropriateness of granitic residual soil used as fillings of high-speed railways foundation bed bottom and embankment, the clay mineral composition, fluid plasticity index, CBR value, relationship between cumulative residual strain and loading time and critical dynamic stress, etc.which are for its engineering properties, are firstly studied.According to codes for design of Chinese and Japanese high-speed railway, it shall be improved that granitic residual soil is not used directly as a high-speed railway subgrade filling.Secondly, according to the experience of improved fine-grained soil in Japan and China, and characteristics of granitic residual soil, it will be identified that cement contents are added extra in granitic residual soil used as fillings of high-speed railways foundation bed bottom and embankment.Thirdly, the comparison of the field test data between finite element analysis results of performance of improved granitic residual soil subgrade under cyclic loading is analyzed; the dynamic similarity analysis of performance of improved granitic residual soil subgrade is carried out; the parameters of cyclic loading test are identified for performance of highway.Finally, The dynamic performance and physico-mechanical characteristics of improved granitic residual soil used in subgrade of Wuhan-Guangzhou high-speed railways in Qingyuan region of Guangdong Province are also studied, relying on PMS - 500 cyclic loading experimental equipment.The dynamic performance and deformation law of improved granitic residual soil subgrade are analyzed under different cyclic loading with and without soaking.It is shown that the improved granitic residual soil could meet the design requirements for all the dynamic indicators and residual settlement of high-speed railway subgrade being influenced by long-term cyclic loading with and without soaking, and could be used to fill the embankment and subgrade bed of highways.%为研究全风化花岗岩用作高速铁路基床底层及路堤本体填料的适宜性,首先,对全风化花岗岩的黏土矿物成分、液塑性指标、承载比CBR值、临界动应力、累积残余应变与加载次数的关系等工程性质进行研究,依据日本和我国高速铁路设计规范要求,得出全风化花岗岩不宜直接作为路基填料,须改良后才能使用;其次,借鉴日本和我国改良土经验,以及全风化花岗岩的工程性质特点,确定它作为高速铁路基床底层及路基本体填料的外加水泥掺量;接着,通过有限元计算与现场行车动测数据结果对比,进行动力相似性分析,获取全风化花岗岩改良土路基的疲劳加载试验参数;最后,使用PMS-500型循环加载系统对新建武广高速铁路清远段全风化花岗岩改良土路基进行现场循环加载试验研究,模拟分析不同载重列车荷载作用下浸水前后全风化花岗岩改良土路基的动态特性及沉降变形规律.试验结果表明,长期循环加载下全风化花岗岩改良土路基动态指标及工后沉降变形量等均满足设计要求,可用作高速铁路的基床底层及路堤本体填料.