高铁路基填料振动压实试验参数标准化方法与应用研究

Study on standardization method and application of vibration compaction test parameters of high-speed railway subgrade filler

振动压实试验作为确定高铁路基粗粒土填料最大干密度方法,缺乏试验参数的标准化研究。为了建立高铁粗粒土填料的振动压实标准与试验方法,通过自行研制大型智能振动压实仪,开展振动压实试验,深入分析试验参数(含水率、尺寸以及振动参数)对干密度的影响规律,揭示振动压实试验参数标准化机制,进一步提出共振下振动压实试验参数的确定方法,最后根据现场碾压试验验证该方法的合理性。研究结果表明:(1)振动压实试验中干密度随着含水率的增大呈现出先减小后增大的规律,但含水率过高,振动压实试验中出现“冒泥”现象,采用烘干后的临界含水率,压实中没有出现“冒泥”现象,且干密度满足现场碾压标准;(2)取3.9作为振动压实试验中径径比(压实筒内径R_(d)与填料最大粒径d_(max)的比值),取3.5作为厚径比(摊铺厚度h_(0)与填料最大粒径d_(max)的比值),可消除压实筒边界尺寸效应对干密度的影响;(3)建立填料级配–固有频率数学模型,试验中将振动频率f设为填料固有频率,参振质量M_(p)设为600 kg,通过调节偏心距控制激振力F与参振质量M_(p)的比值为1.8,填料的最大干密度满足高铁路基压实标准。研究成果可用于振动压实的推广应用,也有助于加深对振动压实机制的理解。

As a method to determine the maximum dry density of coarse-grained soil filler on high-speed railway subgrade,vibration compaction test lacked the standardized research on test parameters.In order to put forward the vibration compaction standard and test method of high-speed railway coarse-grained soil filler,the vibration compaction test was carried out by self-developed large intelligent vibration compaction instrument.The influence of test parameters(water content,size and vibration parameters)on dry density was further analyzed,the standardization mechanism of vibration compaction test parameters was revealed,and the determination method of vibration compaction test parameters under resonance was further proposed.Finally,the rationality of the method was verified according to the field rolling compaction test.The research results show that:(1)With the increase of water content,the dry density of vibration compaction method decreases first and then increases.However,when the water content is too high,the phenomenon of"mud pumping"appears in the vibration compaction test.With the critical water content after drying,there is no phenomenon of"mud pumping"in the compaction,and the dry density meets the on-site rolling compaction standards.(2)Taking 3.9 as the diameter-diameter ratio(the ratio of the inner diameter of the compaction cylinder d R to the maximum particle size of the filler max d)and 3.5 as the thickness-diameter ratio(the ratio of the paving thickness 0 h to the maximum particle size of the filler max d)of the vibration compaction test can eliminate the influence of the boundary size effect of the compaction cylinder on the dry density.(3)The mathematical model of the relationship between filler gradation and natural frequency is established.In the test,the vibration frequency is set as the natural frequency of filler,and the vibratory quality is set as 600 kg.Moreover,when the ratio of excitation force to vibratory quality is controlled to 1.8 by adjusting the eccentricity,the maximum dry density of filler can meet the compaction standard of high-speed railway subgrade.The research results can be used to popularize the vibration compaction method,and also help to deepen the understanding of the mechanism of vibration compaction.