共查询到20条相似文献，搜索用时 578 毫秒
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建筑物和构筑物地基土体的主应力方向往往发生旋转,因此研究初始主应力方向角对黄土动变形特性的影响规律具有一定的现实意义。通过对不同初始应力状态下原状与重塑黄土进行动扭剪三轴试验,研究了初始主应力方向角对黄土动变形特性的影响规律,结果表明:在不同初始主应力方向角下,原状黄土抵抗剪切变形的能力大于重塑黄土;在其他条件相同的情况下,初始主应力方向角越大,黄土抵抗剪切变形的能力越弱;随着初始主应力方向角的增大,黄土的动剪切模量随动剪应变变化的规律呈现出减小的变化趋势,而阻尼比则呈现出增大的变化趋势;初始动剪切模量与最大动剪应力随初始主应力方向角的增大而减小。建议在初始平均主应力较大的情况下,考虑初始主应力方向角对黄土动变形特性的影响,试验成果可为黄土地区工程设计提供一定的参考。 相似文献
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针对黄土地区实现工程施工材料本土化和科学利用粉煤灰问题,对不同配比条件下粉煤灰改性黄土进行重塑非饱和试件的动三轴震陷试验,研究其在动荷载作用下的震陷特性,分析粉煤灰掺入量对动变形模量和动残余应变的影响变化规律。研究结果表明:粉煤灰掺入量对黄土震陷性质的影响较大。相同固结应力水平下,动变形模量和动残余应变随粉煤灰掺入量呈现出不同的变化规律,随着粉煤灰掺入量的增加,黄土动变形模量也随之增大,残余应变则减小。动变形模量与动残余应变之间的变化趋势满足幂函数关系;黄土掺加约20%粉煤灰改性后就能够有良好的抗震陷性能。研究成果可为黄土地区地基的抗震防震设计提供借鉴依据,具有重要的工程实用价值。 相似文献
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对重塑饱和黄土进行静、动力三轴试验,探讨了饱和黄土的静、动力特性。根据静力试验结果分析了饱和黄土静强度的变化规律,建立了饱和黄土的双曲线模型,并推导出其邓肯-张模型参数供本地区工程建设及数值分析参考使用。根据饱和黄土振动三轴试验结果,给出了其在等压固结与非等压固结条件下的动强度变化规律。在对饱和黄土动强度分析的基础上对其进行归一化处理后,建立了饱和黄土静、动强度相关性的经验公式,利用该公式可以实现采用饱和黄土的静力强度参数推求其动强度,从而达到减少场地动力稳定性分析中试验工作量的目的。 相似文献
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不同地区黄土阻尼比变化特性试验研究 总被引：5，自引：0，他引：5
通过兰州、洛川、杨凌地区黄土在不同条件下的动扭剪三轴试验,研究了黄土阻尼比滞回圈形状变化的基本特性以及黄土阻尼比在不同固结压力、不同含水率条件下的变化规律。结果表明,黄土阻尼比滞回圈形状受动剪应变、含水率影响较明显;黄土阻尼比受一般的固结作用的影响并不大,但受含水率的影响较明显。根据含水率的不同,按照半对数坐标中的直线方程,分别给出了兰州、洛川、杨凌地区黄土阻尼比在不同固结压力下的拟合结果,并对拟合结果进行了对比分析;在此基础上,进一步对该三个地区黄土的阻尼比进行了汇总拟合,为西北相近地区黄土在中、大应变条件下的阻尼比取值提供了参考。 相似文献
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《地震研究》2021,44(1)
黄土的细观结构对其非线性动力参数具有重要影响。选取不同地区的典型原状黄土进行室内动三轴试验和扫描电镜(SEM)试验,利用PCAS孔隙图像识别与分析系统统计分析SEM图像,获取了黄土的孔隙细观结构参数,分析了孔隙细观结构参数与初始动弹性模量和阻尼比的关系。结果表明:初始动弹性模量随着土体平均孔隙直径、表观孔隙率、分形维数和概率熵的增大而减小,其中平均孔隙直径和分形维数对初始动弹性模量的影响较为显著,表明土体内孔隙的大小及其排列对土体的动弹性模量具有明显的影响;而阻尼比均随着土体平均孔隙直径、表观孔隙率、分形维数和概率熵的增大呈非线性增大,其与表观孔隙率和分形维数具有明显的相关性,表明孔隙数量及其排列形态对土的阻尼比影响较为明显。 相似文献
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堆石料颗粒形状较为复杂,且存在明显的颗粒破碎特征。为剔除颗粒形状对堆石料动力特性的影响,在不考虑颗粒破碎的情况下,采用玻璃球模拟堆石料进行动三轴试验,分析了试验围压对玻璃球动弹性模量的影响。基于动三轴试验成果,开展了细观数值模拟研究。研究表明：玻璃球的动弹性模量变化规律与堆石料的基本一致;三维颗粒流方程能较好地模拟该材料的动弹性模量特性;随着粗细颗粒直径跨度增大,试样级配关系增强,最大动弹性模量随之增大;细颗粒直径变小和粗颗粒直径变大都将引起最大动弹性模量的增大。试样的动弹性模量随着细观剪切模量的增大而增大,近似为幂函数关系,动应变降低。 相似文献
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1 INTRODUCTION Human activities have resulted in enhanced erosion and sedimentation. The process of erosion, sediment transport, and sedimentation in catchments and rivers commonly causes various sediment disasters. To reduce the potential sediment damage, rapid sediment disaster prediction is needed. The main force of sediment disasters is water movement, so the predictive model of sediment disasters is closely related to conventional hydrodynamic models. Because the formation of sedime… 相似文献
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等幅循环荷载作用下土的动剪模量和阻尼 总被引：3，自引：0，他引：3
本文根据我国南方8个场址81个试样的动三轴试验资料，对土在等幅循环荷载作用下，其动模量和阻尼与应变幅值的关系进行了分析研究，并与现场测试结果进行对比，分析结果，本文提出一种广义双曲线模型，能更满意地描述各类寺应力应变关系，该模型保持了形式简便，参数物理意义明确等优点，文中还分别对砂土和粘土，给出了模型中参数的统计关系式，这些表达式能明显的映粘性土和非粘性土的特性及其差别。 相似文献
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This paper is the first part of the general paper dealing with effects of constitutive modeling of cyclic stress–strain behavior of soils on site amplification. The paper concentrates on modeling of pseudo-static cyclic soil behavior in small to medium strain range. In order to fit the small strain data accurately, the chosen analytical stress–strain relationship should satisfy the specific small strain condition formulated for soils using the small strain data from the pseudo-static cyclic tests. Analysis of conventional relationships, in particular the Ramberg–Osgood (R–O) relationship, indicated that a failure to satisfy this condition lead to low accuracy of prediction of both tangent stiffness and damping ratio at small and medium strains. The logarithmic function originally proposed to describe static monotonic stress–strain behavior is applied to fit experimental cyclic backbone curves. Constructed to satisfy the formulated small strain condition for soils, this function has proven to be free from the limitations of the R–O and other relationships. When applied in combination with the Masing rules to predict damping ratios, it gives a good prediction in the small to medium strain range, where the Masing hypothesis is supported by experimental evidence. 相似文献
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Minimizing sampling disturbance using a new in situ device 总被引：1，自引：0，他引：1
Laboratory tests on soil samples usually underestimate the in situ dynamic soil stiffness. This has been primarily attributed to sampling disturbance. Studies suggest that among the various mechanisms, changes in the stress condition and the soil structure are the main two factors affecting the behavior of soil specimens obtained by conventional sampling methods. The objective of this paper is to investigate this issue, and to introduce the results of laboratory experiments to study the effect of conventional and newly developed sampling methods on dynamic soil properties. 相似文献
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动态监测方法在理论上是可行的，方法也是简便的，有着广阔的发展前景，但是，由于结构的复杂性，测量技术的局限性，单纯依赖理论计算分析诊断结构的病害状况并不总是容易实现的，本文介绍一种依据基本振型的振动反应求局刚度的方法，简单，实用，实践中如果辅以调查，考察，类比，分析．．．，可作出更切合实际的可靠诊断，文中还介绍一些实例，有助于启迪，开拓动态监测的应用领域。 相似文献
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The availability of efficient numerical techniques and high speed computation facilities for carrying out the nonlinear dynamic analysis of soil-structure interaction problems and the analysis of ground response due to earthquake loading increase the demand for proper estimation of dynamic properties of soil at small strain as well as at large strain levels. Accurate evaluation of strain dependent dynamic properties of soil such as shear modulus and damping characteristics along with the liquefaction potential are the most important criteria for the assessments of geotechnical problems involving dynamic loading. In this paper the results of resonant column tests and undrained cyclic triaxial tests are presented for Kasai River sand. A new correlation for dynamic shear damping (Ds) and maximum dynamic shear modulus (Gmax) are proposed for the sand at small strain. The proposed relationships and the observed experimental data match quite well. The proposed relationships are also compared with the published relationships for other sands. The liquefaction potential of the sand is estimated at different relative densities and the damping characteristics at large strain level is also reported. An attempt has been made to correlate the Gmax with the cyclic strength of the soil and also with the deviator stress (at 1% strain) from static triaxial tests. 相似文献