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161.
162.
三相介质饱和土自由场中爆炸波的传播规律 总被引:5,自引:0,他引:5
饱和土是由固体上颗粒、水和少量封闭的空气组成的三相介质。介绍了爆炸波作用下三相介质饱和土有限元基本方程的建立过程,推导了引进人工粘性项的动力有限元方程,得到在饱和土自由场中爆炸波的传播规律;不同空气含量饱和土中爆炸波随深度的衰减规律。文中还给出了有限元与有限差分间断分解结果的比较,以说明本文理论方法的有效性。 相似文献
163.
The stress vector-based constitutive model for cohesionless soil, proposed by SHI Hong-yan et al., was applied to analyze
the deformation behaviors of materials subjected to various stress paths. The result of analysis shows that the constitutive
model can capture well the main deformation behavior of cohesionless soil, such as stress-strain nonlinearity, hardening property,
dilatancy, stress path dependency, non-coaxiality between the principal stress and the principal strain increment directions,
and the coupling of mean effective and deviatoric stress with deformation. In addition, the model can also take into account
the rotation of principal stress axes and the influence of intermediate principal stress on deformation and strength of soil
simultaneously. The excellent agreement between the predicted and measured behavior indicates the comprehensive applicability
of the model.
Biography: SHI Hong-yan (1962-), Associate Professor, Doctor 相似文献
164.
土-桩-结构相互作用体系随机地震反应分析 总被引:2,自引:0,他引:2
本文采用随机振动理论与有限元技术相结合的方法,以基岩随机地震作为输入,对群桩基础和土-桩-结构相互作用体系进行了三维随机地震反应分析。文中首先以一3X3群桩基础作为分析模型,探讨了桩-土-桩动力相互作用对承台随机地震反应的影响;然后,用单自由度体系模拟上部结构,分析了上部结构惯性对桩基承台随机地震反应的影响。在此基础上,以某桥桥墩为背景,用多自由度体系模拟上部结构,建立了土-桩-结构相互作用体系的三维分析模型,获得了桩基承台的功率谱响应、以及桩顶处的主应力标准差和主应力速率标准差等结果,探讨了群桩顶部各桩主应力标准差的分布规律,得到了一些有应用价值的结果。 相似文献
165.
粗粒土与结构接触面受载过程中的损伤 总被引:8,自引:0,他引:8
进行了粗粒上与结构接触面单调和循环加载试验,基于宏细观测量结果,扩展了损伤概念以描述该类接触面在受载过程中的物态演化,及由于物态演化导致的力学特性从初始状态到最终稳定状态的连续变化过程.揭示了接触面损伤的细观物理基础主要是接触面内土的颗牲破碎和剪切压密这两种物态演化;指出接触面的剪胀体应变可以划分为可逆性和不可逆性剪胀体应变两部分,其中不可逆性剪胀体应变可作为接触面损伤发展的宏观量度,因此其归一化形式可作为一种损伤因子的定义;提出了建立粗粒土与结构接触面一种损伤本构关系的基本思路. 相似文献
166.
Hyung-gyu Jun Thomas R. Way Bjrn Lfgren Mats Landstrm Alvin C. Bailey Eddie C. Burt Timothy P. McDonald 《Journal of Terramechanics》2004,41(4):209-222
A Trelleborg Twin 421 Mark II 600/55-26.5 steel-reinforced bias-ply forwarder drive tire at inflation pressures of 100 and 240 kPa and dynamic loads of 23.9 and 40 kN was used at 5% travel reduction on a firm clay soil. Effects of dynamic load and inflation pressure on soil–tire contact pressures were determined using six pressure transducers mounted on the tire tread. Three were mounted on the face of a lug and three at corresponding locations on the undertread. Contact angles increased with decreases in inflation pressure and increases in dynamic load. Contact pressures on a lug at the edge of the tire increased as dynamic load increased. Mean and peak pressures on the undertread generally were less than those on a lug. The peak pressures on a lug occurred forward of the axle in nearly all combinations of dynamic load, inflation pressure, and pressure sensor location, and peak pressures on the undertread occurred to the rear of the axle in most of the combinations. Ratios of the peak contact pressure to the inflation pressure ranged from 0 at the edge of the undertread for three combinations of dynamic load and inflation pressure to 8.39 for the pressure sensor on a lug, near the tire centerline, when the tire was underinflated. At constant dynamic load, net traction and tractive efficiency decreased as inflation pressure increased. 相似文献
167.
Various versions of representations of the percolation Reynolds number for porous media with isotropic and anisotropic flow properties are considered. The formulas are derived and the variants are analyzed with reference to model porous media with a periodic microstructure formed by systems of capillaries and packings consisting of spheres of constant diameter (ideal and fictitious porous media, respectively). A generalization of the Kozeny formula is given for determining the capillary diameter in an ideal porous medium equivalent to a fictitious medium with respect to permeability and porosity and it is shown that the capillary diameter is nonuniquely determined. Relations for recalculating values of the Reynolds number determined by means of formulas proposed earlier are given and it is shown that taking the microstructure of porous media into account, as proposed in [1, 2], makes it possible to explain the large scatter of the numerical values of the Reynolds number in processing the experimental data. 相似文献
168.
STRUCTURAL DAMAGE MODEL OF UNSATURATED EXPANSIVE SOIL AND ITS APPLICATION IN MULTI-FIELD COUPLE ANALYSIS ON EXPANSIVE SOIL SLOPE 总被引:1,自引:0,他引:1
Focused on the sensitivity to climate change and the special mechanical characteristics of undisturbed expansive soil, an elastc-plastic damage constitutive model was proposed based on the mechanics of unsaturated soil and the mechanics of damage. Undisturbed expansive soil was considered as a compound of non-damaged part and damaged part. The behavior of the non-damaged part was described using non-linear constitutive model of unsaturated soil. The property of the damaged part was described using a damage evolution equation and two yield surfaces, i.e., loading yield (LY) and shear yield (SY). Furthermore, a consolidation model for unsaturated undisturbed expansive soil was established and a FEM program named UESEPDC was designed. Numerical analysis on solid-liquid-gas tri-phases and multi-field couple problem was conducted for four stages and fields of stress, displacement, pore water pressure, pore air pressure, water content, suction, and the damage region as well as plastic region in an expansive soil slope were obtained. 相似文献
169.
170.
力学可以为农业现代化作贡献 总被引:10,自引:0,他引:10
农业现代化提出了许多与力学各个分支都有密切关系的问题.从农田耕作、农业物料性质、农产品烘干、水果和蔬菜生产、农业生物环境、节水灌溉、农业水土资源合理利用和作物生长等方面,介绍了有关的力学问题和目前的研究进展. 相似文献