高速铁路要为列车的高速行驶提供一个高平顺性和稳定性的轨下基础，这
无疑是对高速铁路的沉降稳定提出了很高的要求。桩基在现代工程中被广泛使用，它们的基础承受的荷载也越来越大，正确计算这类建筑物的沉降是设计过程中的一个重要环节,单桩的竖向承载力特性方面尚有许多问题需要进行深入研究。
在竖向荷载作用下的桩基础，其沉降的变形性是桩、承台、地基土之间相互影响的结果，由于地基土的复杂多变性以及成桩工艺、桩型及布桩方式的多样性，桩基沉降计算历来是桩基础设计中的一个难题，尽管目前已经提出了很多有关桩基础沉降计算的方法，但都有各自的适用范围和特点，在最终沉降计算方面，首先介绍了群桩最终沉降计算方法及现状。其次，采用GLGPCS程序计算了工点群桩基础的最终沉降，并将其结果与现行规范方法和实测值进行了比较分析。最后，通过该程序的计算，总结了荷载水平、土性、承台底土的刚度、桩长、桩间距等影响因素对群桩最终沉降、群桩桩顶荷载分布、各基桩桩侧阻的发挥、各基桩总的端阻力、承台土反力和承台分担荷载、桩顶面的平均桩土应力比等承载特性的影响规律。
通过上述研究，全面了解了影响群桩沉降的主要因素和变形特性，为高速铁路的设计和施工提供了较为充分的数据参考和技术支持，对我国同类铁路桥梁桩基的设计具有参考价值和一定的实际意义。

The high speed running of train needs smooth and stable foundation of track undersurface.lt means that a high quality of stability for the settlement is needed for high-speed railway.Pile foundations are widely used in civil engineering,and building become higher and higher,their foundation support bigger and bigger structural loads,so settlement evaluation come to be an important step in design of these kind of engineering.there are several problems on the mechanics of vertical beaning capacity for a single pile.
But settlement behavior of pile foundation under axial load is the results of pile-raft-soil interaction,settlement evaluation is always a problem in design of pile doundation because of the complexity of piles.At presents,many settlement evaluation methods of pile foundation have been put forward by engineers and researchers,but these methods have their own characteristics and epplicability.There are several main works of the ultimate settlement.Firstly,thethesis presents the development of calculatingsettlement of pile groupfoundation at present.Secondly,ultimate settlement of pile group foundation is calculated with the GLGPCS software package foundation. The result is compared with current as well.Thirdly,the working rules of the ultimate settlement,the axial pressure,side friction and tip resistance of the pile,load ratio by cap and pile,load ratio by cap and pier-subsoil average stress of soil,load-level,spacing and length of piles,compressibility modulus of soil are analyzed and summarized.
With the listed above analysis the main characteristics of settlement behavior and the main factors of group-pile foundation displacement can be fully understood. for the design and construction of high-speed railway and references to the similarity.lt is definite value in practice.