This paper is titled as " analysis of the stress field of deep foundation pit engineering in loess area by finite element method " , and it aims at simulating the process of excavating and retaining of the deep foundation pit engineering , calculating and analyzing the pressure and deformation of the surrounding soil , and the deformation of retaining structure in the course of excavating in loess area . thus , this paper provides a the ory base for foundation - retaining - structure design , which aims at deflection - control 本论文题目拟为“黄土深基坑应力场的有限元分析” ，目的在于对黄土地区深基坑开挖与支护过程进行模拟，对深基坑周围土体的压力、变形及支护结构的变形随基坑开挖过程所发生的变化进行计算与分析，从而为以变形控制为目的的深基坑支护设计提供理论基础。
Considering the difference of geological condition and construction condition , the thesis select the best form to save the money and make the work in security . a ) the pile support : according cantilever supporting pile , one - anchored supporting pile , the thesis compile a series of program with the method of criterion 本文针对黄土地区悬臂支护桩、单层锚杆支护桩、土钉支护等不同的支护方案，优选了支护方法和结构形式，考虑了不同的地质条件和施工条件情况下，采用相应较合理的支护方案以达到安全可靠和经济的目的。
Lime - soil compaction pile is one of the most normal and effective soil improvement methods in loess area , especially in collapsible loess ones . there is few analysis and study about the compaction characteristic of soil between piles when making holes . the evaluation methods about the compacted effect between piles are different in the various standards on soil improvement 灰土挤密桩作为黄土地区，特别是湿陷性黄土地区最常用、最有效的地基处理方法之一，但对桩间土在成孔过程中挤密性状的分析和研究不是很多，在历次规范中，对桩间土挤密效果的评价方法各不相同，也就是对桩间土中最具有代表平均挤密效果的点的选取存在差异。
So , the following questions such as : how to simulate the process of excavating and retaining of the deep foundation pit engineering , how to calculate and analyze the pressure and deformation of the surrounding soil , how to calculate and analyze the deformation of retaining structure in the course of excavating , how to predict the earth subsidence and the swelling of pit bottom , and how to predict the deflection of surrounding pipes in loess area , are all worth researching 黄土地区深基坑工程技术与理论研究尚处于起步阶段，因此如何对黄土地区深基坑开挖与支护过程进行模拟，对深基坑周围土体的压力、变形及支护结构的变形随基坑开挖过程所发生的变化进行计算与分析，对地表面的沉降和坑底的隆起、周围管线的变位进行预报则成为一个值得研究的课题。
The collapsible loess is often met during the construction of the high - grade highway in the loess area , and the main failure is the uneven subsidence of the roadbed and the culvert , which affects the safe usage of the roadbed and the culvert , etc . directed against this , based on the chankou - lanzhou freeway construction , the paper analyzes the application of the composite ground formed by lime - soil pile under the bridge and designs the project , discusses the rules of the contact pressure , the stress ratio of the pile and the soil , compares the p - s curves of one pile , the composite ground formed by one pile and the composite ground formed by two piles based on the in - situ plate loading test , evaluates the bearing capacity of the composite ground of the project 黄土地区的高等级公路建设中经常遇到湿陷性黄土问题，其病害类型主要是地基土受水浸湿后引起路基、桥台、涵洞等的不均匀沉降，直接影响路基、构造物等的正常使用。针对此问题，本文依托甘肃谗口至兰州柳沟河高速公路建设工程，对桥基灰土桩复合地基应用的可行性进行了深入分析，根据具体工程进行了合理的设计与计算，并配合现场静载荷试验及压力盒实测数据，探讨了基底应力分布规律，桩土应力比，变形模量的变化关系，对比分析了单桩、单桩复合和双桩复合的p ? s关系，对桥基灰土桩复合地基承载力进行了整体评价。
On the basis of the loess distribution , engineering geology and specific properties of road use in gansu province , this paper divides traffic volume grade according to the conditions of transportation of all high - grade highways which are being built and have already finished . besides , it analyses the relativity of three different test methods , establishes the related relations , and divides their strength grade after measuring rebound module of subgrade of the representative high - grade highways in gansu loess area . furthermore , it recommends the common semi - rigid and asphalt concrete design parameters by comparing the experiment in doors to outdoors , and draws up the optimized design program aga - lq based on advanced genetic algorithm and solves the non - liner optimization design model of asphalt pavement construction by computer 本文基于甘肃黄土分布、工程地质及路用特性研究，对该黄土地区在建和已建的全部高等级公路交通状况进行了详细调查和分析，划分了交通量等级；对甘肃黄土地区代表性的高等级公路，利用三种不同方法实测了土基回弹模量，分析了各测试方法的相关性，建立了相关关系，对土基回弹模量进行了强度等级划分；通过室内外试验比较，推荐了常用的半刚性材料和沥青混凝土设计参数值；利用计算机编制了基于改进遗传算法的优化设计程序aga ? lq ，并成功求解了沥青路面结构非线性优化设计模型；最后经计算提出了甘肃黄土地区高等级公路沥青路面典型结构，并编制了查询图库软件cx ? lq ，供设计单位直接选用，科学简便地解决了甘肃黄土地区的路面设计问题。
