基于Ls-DYNA的动力沉桩全过程分析
发布时间：2018-09-06 14:32
【摘要】：动力沉桩被广泛的应用于地基基础以及各种场地,由于其沉桩过程动力特性比较明显,桩和土的应力状态比较复杂,涉及到土力学、弹塑性力学、结构动力学等学科,研究其规律具有深远的意义,一直以来,人们运用各种方法研究动力沉桩的规律,让人们对于桩和土有了进一步本质的认识,对今后打桩施工过程以及桩在土中的各种问题具有指导意义。 本文以DYNA计算软件为工具,运用欧拉网格模拟土体以及用拉格朗日网格模拟基桩,将锤体视为刚体,模拟打桩下沉的全过程。欧拉网格适用于大变形,非常好的解决了土体变形问题,流固耦合技术实现桩土相互作用的过程,重启动技术实现了锤体多次锤击桩的过程。 得到了若干结论,(1)锤击力曲线有多次波峰波谷,并且相邻波峰的幅值都会下降,并且到达第六次波峰之后,曲线开始进入平稳阶段,桩顶位置随着锤击次数的增加匀速地下降,每次锤击下沉量相差不大,曲线类似于直线。(2)锤击过程中锤击力的最大峰值与锤击次数以及桩的入土深度无明显关系。(3)桩上任意时刻应力分布都是其应力波在桩中反射和叠加造成的结果。(4)桩中间部分的拉应力和压应力幅值明显高于两端的应力幅值,所以在打桩的过程中,桩身中间部位要引起足够的重视,可以布置更多的预应力钢筋来抵抗较高的拉应力,用高等级混凝土来抵抗较高的压应力。(5)得到了土中应力的分布特征和随着打桩下沉过程土中应力的变化特点。(6)得到了锤击中沉桩阻力随时间变化的曲线。
[Abstract]:Dynamic piling is widely used in foundation and various sites. Because of its obvious dynamic characteristics of piling process and complex stress state of pile and soil, it involves soil mechanics, elastic-plastic mechanics, structural dynamics and so on. It is of great significance to study the law of dynamic piling. All along, people have used various methods to study the law of dynamic piling, which makes people have a further understanding of the nature of pile and soil. It is of guiding significance for future piling construction process and various problems of pile in soil. In this paper, the DYNA software is used to simulate the soil mass with Euler mesh and the foundation pile is simulated with Lagrange grid. The hammer body is regarded as a rigid body and the whole process of pile sinking is simulated. Euler mesh is suitable for large deformation, which solves the problem of soil deformation very well, realizes the process of pile-soil interaction by fluid-solid coupling technology, and restarts the process of hammering pile with multiple hammers. Some conclusions are obtained: (1) there are multiple peaks and valleys in the hammer force curve, and the amplitude of the adjacent peaks will decrease. After reaching the sixth wave peak, the curve begins to enter the stationary stage, and the position of the pile top decreases uniformly with the increase of the hammering times. There is little difference in the amount of sinking per hammer, The curve is similar to a straight line. (2) the maximum peak value of the hammering force has no obvious relationship with the number of hammering and the depth of the pile. (3) the stress distribution at any time on the pile is the result of the reflection and superposition of the stress wave in the pile. The amplitude of tensile stress and compressive stress in the middle part of pile is obviously higher than that in both ends. So in the process of piling, we should pay enough attention to the middle part of the pile body so that more prestressed steel bars can be arranged to resist the higher tensile stress. High grade concrete is used to resist high compressive stress. (5) the distribution characteristics of stress in soil and the variation characteristics of stress in soil with piling sinking are obtained. (6) the curve of resistance of pile sinking with time is obtained.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU753.3
[Abstract]:Dynamic piling is widely used in foundation and various sites. Because of its obvious dynamic characteristics of piling process and complex stress state of pile and soil, it involves soil mechanics, elastic-plastic mechanics, structural dynamics and so on. It is of great significance to study the law of dynamic piling. All along, people have used various methods to study the law of dynamic piling, which makes people have a further understanding of the nature of pile and soil. It is of guiding significance for future piling construction process and various problems of pile in soil. In this paper, the DYNA software is used to simulate the soil mass with Euler mesh and the foundation pile is simulated with Lagrange grid. The hammer body is regarded as a rigid body and the whole process of pile sinking is simulated. Euler mesh is suitable for large deformation, which solves the problem of soil deformation very well, realizes the process of pile-soil interaction by fluid-solid coupling technology, and restarts the process of hammering pile with multiple hammers. Some conclusions are obtained: (1) there are multiple peaks and valleys in the hammer force curve, and the amplitude of the adjacent peaks will decrease. After reaching the sixth wave peak, the curve begins to enter the stationary stage, and the position of the pile top decreases uniformly with the increase of the hammering times. There is little difference in the amount of sinking per hammer, The curve is similar to a straight line. (2) the maximum peak value of the hammering force has no obvious relationship with the number of hammering and the depth of the pile. (3) the stress distribution at any time on the pile is the result of the reflection and superposition of the stress wave in the pile. The amplitude of tensile stress and compressive stress in the middle part of pile is obviously higher than that in both ends. So in the process of piling, we should pay enough attention to the middle part of the pile body so that more prestressed steel bars can be arranged to resist the higher tensile stress. High grade concrete is used to resist high compressive stress. (5) the distribution characteristics of stress in soil and the variation characteristics of stress in soil with piling sinking are obtained. (6) the curve of resistance of pile sinking with time is obtained.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU753.3
【参考文献】
相关期刊论文 前10条
1 施建勇,彭R，
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