【摘 要】
：
As important methods to guide the field soil compaction,the standard and modified Proctor tests for laboratory compaction have remained unchanged for decades,which should be improved to better understand the compaction process and the properties of soils.
【机 构】
：
Department of Civil and Environmental Engineering,University of Tennessee,Knoxville,851 Neyland Dr,K
论文部分内容阅读
As important methods to guide the field soil compaction,the standard and modified Proctor tests for laboratory compaction have remained unchanged for decades,which should be improved to better understand the compaction process and the properties of soils.In this study,an accelerometer was installed on a Marshall impact compactor to capture the dynamic response of three types of soils during compaction.The experimental test results indicated that the acceleration curve for each blow gradually evolved to a stable pattern following the progress of compaction,and the impact and gyratory locking points were linearly related with coefficient of determination R2 equal to 0.59.The impact compaction curve could be further constructed by filtering the structural resonance,which can be used to quantify the compactability of soil materials.Although each type of soil had a unique set of compaction curves,the slope and value of compaction curve altered accordingly as the moisture content changed for the same soil.In addition,the average acceleration value at the final compaction stage could serve as the target value of soil stiffness.
其他文献
为探明高地应力层状软岩隧道非对称大变形特征,收集200个高地应力层状软岩隧道大变形案例数据,统计分析非对称大变形的影响因素,采用关联规则方法分析隧道相对变形量、非对称变形部位,研究非对称大变形分级修正方法.结果表明:高地应力层状软岩隧道大变形分级非对称主要因素为岩层倾角α、岩层走向与隧道轴线夹角β、原岩应力场最大主应力与岩层面夹角γ.得到大变形分级基本因素(围岩抗压强度、最大主应力值)与相对变形量、大变形分级非对称主要因素(α,β,γ)与非对称变形部位之间的20条强关联规则,揭示了α,β,γ与非对称变形的
为弥补传统动力Winkler地基梁模型在单桩水平动力响应分析中的不足,基于Timoshenko梁理论和Pasternak地基理论,建立同时考虑土体剪切效应和桩身剪切变形的Timoshenko-Pasternak模型.首先,从土体三维波动方程出发,借助微分变换解耦土体方程,利用分离变量法结合桩土边界连续性条件求解桩周土水平阻抗;在此基础上,利用Timoshenko-Pasternak模型推导单桩水平振动控制方程,运用传递矩阵法结合桩底边界条件得到桩顶动力复阻抗频域解析解.通过与已有模型解进行对比,验证该模型
Dominant frequency attenuation is a significant concern for frequency-based criteria of blasting vibration control.It is necessary to develop a concise and practical prediction equation describing dominant fre-quency attenuation.In this paper,a prediction
It is difficult to temporally and spatially track and characterize the slurry viscosity in flowing water during grouting simulation.In this study,a sequential flow and solidification(SFS)method considering the spatial-temporal evolution of slurry viscosit
内部侵蚀是造成堤防、大坝、路基等诸多结构失稳的主要原因之一.现有对土体内部侵蚀特性的研究大多基于静态加载,且无法定量描述细颗粒迁移的相关规律.为此,采用自主研发的土体渗透试验装置,对2组不同级配的染色标定砂土开展循环荷载作用下的内部侵蚀试验,探究循环荷载下砂土内部侵蚀过程中的水力响应机制,并定量描述流失颗粒的粒径组成及成分来源.试验结果表明:循环荷载-水头作用下,在现有土体稳定性判别方法中表现为稳定土体的试样A仍发生了一定质量的颗粒流失,之后又会达到新的平衡状态;而表现为不稳定土体的试样B则会发生持续且显
The unprecedented rate of metro construction has led to a highly complex network of metro lines.Tunnels are being overlapped to an ever-increasing degree.This paper investigates the deformation response of double-track overlapped tunnels in Tianjin,China
后疫情时代,滞胀和债务危机风险并存,成为全球经济的重要挑战.本文发现,基准情形下,各国面临的滞胀压力和债务危机风险均有望缓解,但仍需警惕负向的供给冲击进一步持续、各国经济复苏分化加剧、主要经济体逆周期政策退出时点选择不当等风险事件.极端情形下,局部地区乃至更多国家或因上述风险事件陷入滞胀或爆发债务危机.中国应坚持“以我为主”的宏观经济政策框架,同时积极加强卫生和金融领域的国际合作.
本文利用2013年取消贷款利率下限的准自然实验,采用PSM-DID方法系统检验放松利率管制对企业风险承担的影响,得出以下研究结论与启示:第一,取消贷款利率管制后,民营企业的风险承担水平显著提高,相较而言,仅放松贷款利率上限对企业风险承担无显著影响.第二,基于横截面异质性的机制检验发现,在中西部地区、融资约束较严重和财务风险较低的企业中,放松利率管制对风险承担有更显著的正向影响.最后,放松利率管制通过提升企业风险承担,在降低企业投资不足问题的同时,也逐步增加企业的过度投资水平.
Existing mechanism of simulating soil movement at tunnel face is generally based on the translational or rotational velocity field,which is,to some extent,different from the real soil movement in the arching zone.Numerical simulations are carried out firs
Predicting rock cracking is important for assessing the stability of underground engineering.The effects of the intersecting angle α and the distribution orientation angle β of intersecting fissures on the uniaxial compressive strength and the failure cha