帮写美国assignment：上海联华河畔景苑倒楼工程报告

Abstract：摘要 

基于结构的设计理念和土木工程建筑业的原则，机制和上海莲花河畔景苑七号楼的倒塌不可或缺的主要的原因进行了分析各方面，如工程地质条件，预应力桩基础开挖及水位在下降土等南部基坑压差提议地下室应扁型高层住宅建筑和正确的施工程序进行设置，应采用............新的设计Based on structural design concept and civil engineering construction principle, the mechanism and primary reasons for the integral collapse of Shanghai Lotus River Garden No．7 Building are analyzed on various aspects, such as engineering geological conditions, prestressed pile foundation excavation and water level lowering in the south foundation pit and pressure difference of soil, etc. It is proposed that basement shall be set in flat－type high－rise residential buildings and correct construction procedures shall be adopted．…………new design

CE Database subject headings: high－rise residential building; collapse of structure; soft soil; pile foundation
Key words： high－rise residential building; collapse of structure; soft soil; pile foundation
 

Introduction 介绍

6月27日2009年，一个新建的上海莲花河畔景苑7号住宅楼发生倾覆造成一人伤亡这是中国建筑行业数十年罕见的重大事故见图1.该建筑的整体倾覆是由引起的各种原因。土木工程应进一步倒塌建筑物的机理分析，从事故获得的经验教训。虽然事故调查组在上海已经放弃了计划中的大楼整体倾覆的主要原因。它被通知工程地质勘察报告，原结构设计均符合该规范的要求，在地下室中使用管桩是满足基本质量要求。通过仔细的分析和反思，并查看各种媒体的分析和评论提议的机制崩溃分析，其原因是现在推翻建设和经验教训的原因，从绘制。On June 27 of 2009, A newly built Shanghai Lotus river garden NO．7 residential building has happened overturning caused one casualty which is a rare major accident of China's construction industry for decades see in Fig 1. The building's overall overturning was caused by a variety of reasons. Civil engineering should further analysis of the mechanism of collapsed of the building and get experiences and lesson from the accident. Although the accident investigation team in Shanghai has been gave the main reason for the proposed building overall overturn. It is notified that the engineering geological investigation report and the original structure design are accord to the requirement of the specification, pipe piles used in the basement are meet basic quality requirements. By careful analysis and reflection, and review the reasons for the collapse analysis of a variety of media analysis and comment on the proposed mechanism and the reason is now overturning the building and the lessons to be drawn from.

Reasons for the collapse of the building

2.1 The site engineering geological condition
the common engineering geological conditions Shanghai area are: below the surface about 3 ~ 4 m to enter the soft sandy soil, local civil engineering profession called "iron sand" It is a blue sand, but in some places there are yellow. The capacity of the layer is strong when the soil carry little water, but when soil become saturated soil which has no bearing capacity. This layer is divided into several sub-layers which have the same geological condition, The total thickness of the layer is about 17 ~ 18 m relatively distributed throughout the urban area, It should be carefully deal with the foundation in Shanghai when structure encounter the "iron sand" layer. Once the Precipitation and seepage are not get well done, There will be a quick blasting with sand and water. The pressure of water will push water and sad from the foundation, soil erosion serious loss rate outside the foundation, and soon, a few hours after the foundation pit lateral will appear big collapse. Hazards and defects that exist in the Shanghai area of geological engineering, In this special zone Dianpu river banks may be more severe, it is a test of the builders of the wisdom and ability to handle the project.

Fig. 1. Collapse of building NO 7
2.2pipe pile foundation construction of Building 
Prestressed pipe is generally smaller in diameter,  but its length is longer in most case so the belong to slender member that easily cause instability problem, single pipe has high vertical bearing capacity, capacity of C80 high strength prestressed pile with 500mm diameter in Shanghai region can get to 2200 kPa or more. But it required the physical surrounding soil to provide good lateral restraint to its full vertical bearing capacity.&