基于Ls-DYNA的動力沉樁全過程分析
發(fā)布時間：2018-09-06 14:32
【摘要】：動力沉樁被廣泛的應用于地基基礎以及各種場地,由于其沉樁過程動力特性比較明顯,樁和土的應力狀態(tài)比較復雜,涉及到土力學、彈塑性力學、結構動力學等學科,研究其規(guī)律具有深遠的意義,一直以來,人們運用各種方法研究動力沉樁的規(guī)律,讓人們對于樁和土有了進一步本質(zhì)的認識,對今后打樁施工過程以及樁在土中的各種問題具有指導意義。 本文以DYNA計算軟件為工具,運用歐拉網(wǎng)格模擬土體以及用拉格朗日網(wǎng)格模擬基樁,將錘體視為剛體,模擬打樁下沉的全過程。歐拉網(wǎng)格適用于大變形,非常好的解決了土體變形問題,流固耦合技術實現(xiàn)樁土相互作用的過程,重啟動技術實現(xiàn)了錘體多次錘擊樁的過程。 得到了若干結論,(1)錘擊力曲線有多次波峰波谷,并且相鄰波峰的幅值都會下降,并且到達第六次波峰之后,曲線開始進入平穩(wěn)階段,樁頂位置隨著錘擊次數(shù)的增加勻速地下降,每次錘擊下沉量相差不大,曲線類似于直線。(2)錘擊過程中錘擊力的最大峰值與錘擊次數(shù)以及樁的入土深度無明顯關系。(3)樁上任意時刻應力分布都是其應力波在樁中反射和疊加造成的結果。(4)樁中間部分的拉應力和壓應力幅值明顯高于兩端的應力幅值,所以在打樁的過程中,樁身中間部位要引起足夠的重視,可以布置更多的預應力鋼筋來抵抗較高的拉應力,用高等級混凝土來抵抗較高的壓應力。(5)得到了土中應力的分布特征和隨著打樁下沉過程土中應力的變化特點。(6)得到了錘擊中沉樁阻力隨時間變化的曲線。
[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.
【學位授予單位】：武漢理工大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：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.
【學位授予單位】：武漢理工大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU753.3
【參考文獻】
相關期刊論文 前10條
1 施建勇,彭R，
本文編號：2226648
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