基于管桩动力沉桩效应对饱和粉土特性的试验研究
发布时间：2018-07-29 10:23
【摘要】：随着高层、超高层建筑物、深水港口及大跨度桥梁等工程的发展,预应力管桩在工程中的应用范围越来越广,因此,对预应力管桩沉桩的质量要求将会更高。本文主要对预应力管桩沉桩过程中荷载传递方法及沉桩阻力进行分析,为确定沉桩的外在动力和选择振动锤奠定了基础。沉桩过程中,桩周围土体的性状受到循环振动荷载的作用将会发生变化。对于饱和粉土层,在循环振动荷载作用下土体的结构性能将被破坏,将会发生液化现象,使得桩更容易贯入土体中。在振动沉桩过程中,对粉土动强度进行研究是很有必要的。 经过对沉桩过程中相关理论分析的基础上,明确了沉桩过程中粉土动强度破坏标准以后,本文选取饱和粉土,进行动三轴试验,并对试验数据进行分析。研究分析不同干密度和不同固结比对饱和粉土动强度的影响。控制固结比不同,对不同干密度(1.40g/cm3和1.50g/cm3)的粉土,在不同围压(50kPa、100kPa和150kPa)下的动剪切应力与破坏振次的关系曲线进分析得到：在干密度相同和固结比相同的情况下,如破坏振次相同时,随着固结压力(围压)的增大,饱和粉土的动剪切应力也是增大的；或者说破坏时动剪切应力相同时,随着固结压力的增大,破坏所需的振动次数越多；在围压一定时,同一干密度的粉土破坏振次相同的情况下,动剪应力随着固结比的增大而增大,即在围压不变的情况下,粉土在振动循环荷载作用下发生破坏(液化)所需的剪切应力(动应力)随着固结比的增加逐渐提高,在相同的破坏振次下,固结比越大,破坏所需的剪切应力越大。同样可得：在相同的动应力水平下,固结比越大,破坏所需的振次越多。并对所得结论进行了理论上的分析说明。选择试验所得饱和粉土的参数,利用有限差分软件FLAC3D模拟沉桩过程中土体的变化。
[Abstract]:With the development of high-rise building, deep water port and long-span bridge, the application of prestressed pipe pile in engineering is more and more extensive. Therefore, the quality requirement of prestressed pipe pile will be higher. This paper mainly analyzes the load transfer method and pile driving resistance in the process of piling with prestressed pipe pile, which lays a foundation for determining the external dynamic force of pile driving and selecting vibration hammer. In the process of piling, the behavior of soil around the pile is affected by cyclic vibration load. For saturated silt soil, the structure performance of soil will be destroyed under cyclic vibration load, and liquefaction will occur, which makes it easier for the pile to penetrate into the soil. It is necessary to study the dynamic strength of silt during vibration piling. On the basis of the analysis of the relevant theory in the process of piling, the failure criterion of dynamic strength of silt in the course of piling is clarified, the saturated silt is selected in this paper, the dynamic triaxial test is carried out, and the test data are analyzed. The effect of different dry density and consolidation ratio on the dynamic strength of saturated silt was studied. For silty soil with different dry density (1.40g/cm3 and 1.50g/cm3), the relationship between dynamic shear stress and failure vibration times under different confining pressures (50kPa100kPa and 150kPa) is obtained by curve analysis under the same dry density and the same consolidation ratio. If the failure vibration times are the same, the dynamic shear stress of saturated silt increases with the increase of consolidation pressure (confining pressure), or when the dynamic shear stress is the same, the more vibration times are needed with the increase of consolidation pressure. When the confining pressure is constant, the dynamic shear stress increases with the increase of the consolidation ratio, that is, when the confining pressure is constant, the failure vibration of silt of the same dry density is the same. The shear stress (dynamic stress) required for failure (liquefaction) of silty soil under vibration cyclic loading increases gradually with the increase of consolidation ratio. The greater the consolidation ratio is, the greater the shear stress is required for failure. At the same dynamic stress level, the larger the consolidation ratio, the more vibration is needed to destroy. The conclusions are analyzed and explained theoretically. The parameters of saturated silt are selected and the change of soil mass during piling is simulated by finite difference software FLAC3D.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.1;TU41
本文编号：2152378
[Abstract]:With the development of high-rise building, deep water port and long-span bridge, the application of prestressed pipe pile in engineering is more and more extensive. Therefore, the quality requirement of prestressed pipe pile will be higher. This paper mainly analyzes the load transfer method and pile driving resistance in the process of piling with prestressed pipe pile, which lays a foundation for determining the external dynamic force of pile driving and selecting vibration hammer. In the process of piling, the behavior of soil around the pile is affected by cyclic vibration load. For saturated silt soil, the structure performance of soil will be destroyed under cyclic vibration load, and liquefaction will occur, which makes it easier for the pile to penetrate into the soil. It is necessary to study the dynamic strength of silt during vibration piling. On the basis of the analysis of the relevant theory in the process of piling, the failure criterion of dynamic strength of silt in the course of piling is clarified, the saturated silt is selected in this paper, the dynamic triaxial test is carried out, and the test data are analyzed. The effect of different dry density and consolidation ratio on the dynamic strength of saturated silt was studied. For silty soil with different dry density (1.40g/cm3 and 1.50g/cm3), the relationship between dynamic shear stress and failure vibration times under different confining pressures (50kPa100kPa and 150kPa) is obtained by curve analysis under the same dry density and the same consolidation ratio. If the failure vibration times are the same, the dynamic shear stress of saturated silt increases with the increase of consolidation pressure (confining pressure), or when the dynamic shear stress is the same, the more vibration times are needed with the increase of consolidation pressure. When the confining pressure is constant, the dynamic shear stress increases with the increase of the consolidation ratio, that is, when the confining pressure is constant, the failure vibration of silt of the same dry density is the same. The shear stress (dynamic stress) required for failure (liquefaction) of silty soil under vibration cyclic loading increases gradually with the increase of consolidation ratio. The greater the consolidation ratio is, the greater the shear stress is required for failure. At the same dynamic stress level, the larger the consolidation ratio, the more vibration is needed to destroy. The conclusions are analyzed and explained theoretically. The parameters of saturated silt are selected and the change of soil mass during piling is simulated by finite difference software FLAC3D.
【学位授予单位】：扬州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU473.1;TU41
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