粗粒土室内表面振动压实参数及土体结构分析试验研究

发布时间：2018-06-03 23:50

本文选题：粗粒土 + 振动压实技术　；参考：《西南交通大学》2016年硕士论文

【摘要】：表面振动压实是粗粒土室内标准最大干密度的重要试验方法,公路、铁路试验规程均将其作为室内最大干密度试验的方法之一。表面振动压实来源于“更接近于现场振动压路机振动碾压的实际状况”这一思想,对于室内试验,主要是对影响试验结果的参数进行研究。采用粗粒土进行室内表面振动压实试验并测试振动参数,探讨了表面振动压实参数控制。结合试验结果及压实效能,与重型击实试验进行了对比；基于粗粒料体积填充理论,结合表面振动压实试验,对某高寒地区两种典型天然粗粒土填料的土体结构类型进行试验研究。论文主要工作和结果如下：(1)采用某高铁路基试验段碎石土填料进行表面振动压实试验,同时安装振动传感器测试振动参数,结合各行业规范要求及已有研究成果,对表面振动压实试验参数控制问题进行了探讨。振动压实效果受激振力、振动频率、振幅、振动时间等参数的影响,试验最大干密度值是这些影响参数联合作用的结果；激振力是由仪器构造决定,属于压实机械固有属性。动作用力与仪器设计参数及土体特性均有关,实测动作用力大于仪器激振力,铁路、公路规程规定“激振力”10～80kN的取值范围为钢制夯与土体表面接触时的峰值动作用力更为合理；振动压实显著作用效果时间为1min左右,合理压实振动时间可取3min；同种碎石土样,表面振动压实试验测试最大干密度值小于Z3重型击实试验,约为击实的96%左右；有效做功分析表明,相对于振动压实,击实冲击荷载作用使粗粒土挤压密实效果更好。对于室内振动压实试验的参数控制,可有两种参考思路。一是经过试验验证后,确定适用于大多数粗粒土的最优参数组合,仪器设定固定参数,形成统一参数标准;二是确定合理范围,设置为参数可调,可针对不同情况选择对应合理参数。(2)以某高寒地区两种类型天然粗粒土填料为试验土样,基于体积填充理论,从小到大逐级剔除土样上一级粒径组颗粒后进行表面振动压实试验。根据测试干密度值变化规律,分析土体结构类型,确定骨架颗粒与填充颗粒的分界粒径,为粗粒料的级配改良提供参考。逐级剔除后,悬浮密实结构土体干密度先增大后减小,且变化较大,有陡升或陡降的现象,存在明显分界粒径,土体二元结构特性显著；骨架孔隙结构土体干密度或增加或减小,变化幅度较小,分界粒径不明显；骨架密实结构土体干密度变化曲线相对平缓,剔除最小粒径后,剩余粒径颗粒也能表现出良好的互相填充关系,土体呈多元结构。粗粒含量控制在30%～70%是土体形成骨架结构必要条件,细粒(d0.075mm)含量的界限值在5%～10%较为合理；对于粗粒土,可以分界粒径为界限,分段分析土体级配组成及土体结构类型；当粗粒土不均匀系数很大时,曲率系数不是级配是否优良的严格控制条件。
[Abstract]:Surface vibration compaction is an important test method for indoor standard maximum dry density of coarse grained soil. The surface vibration compaction comes from the idea of "getting closer to the actual condition of vibration compaction in situ". For indoor tests, the parameters that affect the test results are mainly studied. The surface vibration compaction test and vibration parameter measurement were carried out with coarse grained soil, and the control of surface vibration compaction parameters was discussed. Combined with the test results and compaction efficiency, the results were compared with the heavy compaction test, and based on the volume filling theory of coarse grain, combined with the surface vibration compaction test, The soil structure types of two typical natural coarse grained soil fillers in an alpine region were studied experimentally. The main work and results of this paper are as follows: (1) the surface vibration compaction test is carried out with gravel soil filler in a test section of high speed railway subgrade, and vibration parameters are tested by installing vibration sensor, combined with the requirements of various industry specifications and existing research results. The parameter control of surface vibration compaction test is discussed. The effect of vibration compaction is affected by the parameters such as excitation force, vibration frequency, amplitude and vibration time. The maximum dry density is the result of the combined action of these parameters, and the exciting force is determined by the structure of the instrument and belongs to the inherent property of compaction machinery. The action force is related to the design parameters of the instrument and the characteristics of the soil. The measured action force is greater than the exciting force of the instrument. The highway regulations stipulate that the range of "exciting force" 10~80kN is more reasonable when the steel compaction is in contact with the soil surface, the significant effect time of vibration compaction is about 1min, and the reasonable compaction vibration time can be taken for 3 mins. The maximum dry density of surface vibration compaction test is less than that of Z3 heavy compaction test, which is about 96% of that of compaction, and the effective work analysis shows that compacted impact load makes the compaction effect of coarse grained soil better than that of vibration compaction. For the parameter control of indoor vibration compaction test, there are two kinds of reference ideas. One is to determine the optimal combination of parameters suitable for most coarse-grained soils after experimental verification, and the instrument sets fixed parameters to form a unified parameter standard; the other is to determine the reasonable range and set the parameters to be adjustable. Two types of natural coarse grained soil fillers can be selected as experimental soil samples based on volume filling theory. The surface vibration compaction test was carried out after the particle size of the soil sample was removed from small to large step by step. According to the change rule of dry density value, the structure type of soil is analyzed, and the boundary particle size of skeleton particle and filling particle is determined, which provides a reference for improving the gradation of coarse grain. After being eliminated step by step, the dry density of soil in suspended dense structure first increases and then decreases, and changes greatly, there is a phenomenon of steep rise or steep drop, there is obvious boundary particle size, and the dual structure characteristic of soil is remarkable. The dry density of skeleton pore structure soil body increases or decreases, the variation range is small, the boundary particle size is not obvious, and the dry density curve of skeleton pore structure soil mass is relatively smooth, excluding the minimum particle size, The residual particle size can also show a good mutual filling relationship, and the soil is multivariate. Controlling the coarse grain content at 30% is the necessary condition for the formation of skeleton structure of the soil, and the limit value of the fine grain content is 5% 10%, for coarse grained soil, the boundary particle size can be taken as the limit, and the soil gradation composition and soil structure type can be analyzed in sections. When the inhomogeneous coefficient of coarse grained soil is very large, the curvature coefficient is not the strict control condition of whether the gradation is good or not.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU411

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