幼儿园晨会内容顶管论文：大直径砼顶管工程中土与结构的相互作用分析
【中文摘要】随着新技术和设备的不断开发和采用，顶管逐渐向直径大型化的趋势发展。大直径顶管施工对土体的影响与小口径的顶管必然有所不同，因此传统的管道设计方法已不再适用，并且对提供顶力的工作井也提出了更高的要求。本文结合上海市污水治理南线工程，采用数值模拟方法，对顶管施工中管土相互作用、沉井工作井与土的相互作用进行研究。主要工作和研究成果如下:(1)考虑上海软粘土的弹塑性特性，对内径4m的大直径钢筋混凝土顶管管道的受力特性进行了分析。研究了施工过程中管土接触压力的变化及土体参数对管道外土压力的影响，并与现有的计算方法对比，总结管土界面土压力的变化规律。计算结果表明：在上海软土地基中，钢筋混凝土顶管属于刚性管，施工过程中的土拱效应使管道上方和下方土体应力减小，而左右两侧应力增大；土拱效应随覆土厚度的增加逐渐增强，管土接触压力分布比较平均；规范中对侧向土压力采用主动土压力计算偏于保守，将主动土压力系数改为静止土压力系数计算较为合理。(2)对顶力作用下的矩形和圆形沉井的受力特性进行了分析，指出现有计算方法的不足，并研究不同受力状态下的土压力分布规律。计算结果表明：矩形沉井后座墙在顶进力反力作用下的变形表现为抛物线形，墙后土体全部受压，对后背土体采用考虑位移的土压力计算方法来计算土体反力；在极限状态时，沉井后背土体产生整体位移，全部达到被动状态，土体反力按朗肯被动土压力计算。矩形沉井后背滑动体呈圆弧状楔形
体，平面形状为椭圆；圆形沉井后背和前壁的滑动破坏体形状也为楔
形体，平面形状为半圆。(3)对比各种国内外设计方法的不同之处及其设计依据，并结合有限元分析结果，对直线顶管施工过程中管道和沉
井的土压力计算方法进行优化。在中国顶管设计规范的基础上，分别对垂直土压力、侧向土压力和地基反力的取值和土压力分布模式进行调整，提出了两种新的管道设计模式。两者都更符合管道受力的实际性状，并使管道的计算弯矩大为减小，配筋也能相应减小。提出在极限状态时，矩形和圆形沉井水平方向上的土压力分布为：矩形沉井在偏
保护环境的演讲稿
心受力时后背反力呈梯形分布，圆形沉井后背反力增量呈向心余弦分布。
【英文摘要】With the development and adoption of new technique and equipment, the diameter of jacking pipe grow up to be large scale gradually. It’s inevitable that the influence of construction of large diameter jacking pipe was different with narrow pipe. So the traditional design methods of pipe was not suitable, and the working well which provided jacking force asked for higher requirement. Bad on the South Line project of wage treatment, the interaction between soil and pipe, between soil and caisson working well, were investigated respectively by numerical simulation in this disrtation. The major works and results of this disrtation were as follows:(1) Considering the characteristic of elastoplasticity of Shanghai
人工智能就业soft clay, the performance of DN4000 jacking pipe was studied firstly. The variation of contact pressure between pipe and soil during construction was analyzed, and then the influence of soil parameters were discusd. At the same time, the existing computing methods were compared with results of numerical simulation, and the variation laws of earth pressure of the interface were summarized. The computed results were as follows: Reinforced concrete jacking pipe was belong to rigid pipe in Shanghai soft clay. Soil arch effect in the construction would decrea soil stress above and below pipe, while incread soil stress of two sides. Soil arch effect was strengthened with increasing of cover depth, and the distribution of contact pressure was very uniform. Active earth pressure was conrvative to calculate lateral pressure in Chine standard, so it’s more reasonable to change the active earth pressure coefficient to be at rest.(2) Then the performance of rectangular and circular caisson under impellent were studied. The shortages of existing computing methods were pointed out, and the regularities of earth pressure distribution under different stress state were analyzed. The computed results were as follows: Under the counterforce on the rectangular caisson working well during精英计划
pipe jacking, the displacement curve of back wall showed as parabolic while the soil was compresd all behind the back wall. The relation between displacement and earth pressure was us
ed to calculate the earth counterforce. The soil behind back wall deformed entirely and reached to passive state at limiting state, and the vertical earth counterforce was calculated according to Rankine’s passive earth pressure theory. The slide mass behind back wall of rectangular caisson was like a cambered sphenoid, and its flat shape was elliptic. While the slide mass behind back wall of circular caisson was like a sphenoid, and its flat shape was mi-circle.(3) The differences and reasons of various design methods was compared at home and abroad finally. Combined with results of finite element, the computing methods of earth pressure of pipe and caisson are optimized in rectilinear pipe line construction. Bad on Chine jacking pipe standard, the value and load model of vertical and lateral earth pressure, and subgrade counterforce were adjusted, which induced two new design models of jacking pipe. Both of the two models were more corresponding with field practice of pipe, and they could minish computed bending moment of pipe. Accordingly, the ratio of reinforcement could be reduced. At the limiting state, horizontal distribution of earth pressure was propod
残疾人补助申请书>熊妈妈请客for rectangular and circular caisson: The counterforce distribution of back wall was ladder-shaped for rectangular caisson, while the increment distribution of counterforce of back wall was centripetal cosine-shaped for circular caisson.
整天英语
【关键词】顶管沉井大直径受力模式数值模拟
【英文关键词】jacking pipe caisson large diameter load model numerical simulation 【目录】大直径砼顶管工程中土与结构的相互作用分析摘要3-5ABSTRACT5-6第一章绪论9-22 1.1 研究背景与意义9-11 1.2 国内外研究现状11-21 1.2.1 管土相互作用11-14 1.2.2 管道土压力计算14-19 1.2.3 工作井与土体相互作用19-21 1.3 本文的主要研究内容及技术路线21-22第二章钢筋混凝土顶管与土的相互作用分析
22-44 2.1 引言22 2.2 管道受力的数值模拟
22-26 2.2.1 模型简化及计算假定23-24 2.2.2 计算参数的选取24-25 2.2.3 施工过程模拟25-26 2.3 数值模拟结果分析26-33 2.3.1 顶管触变泥浆层的影响分析哺乳期能不能喝茶
26-27 2.3.2 施工过程对管道周围土体的影响
27-30 2.3.3 单管顶进过程的参数分析30-33 2.4 管道土压力的对比改进33-42 2.4.1 管顶垂直土压力的对比
34-37 2.4.2 侧向土压力的对比37-39 2.4.3 地基反力的对比39-40 2.4.4 关于侧向土压力取值的机理分析
