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1、深基坑工程存在的问题和展望 1 Overview In recent years, with the development of economy and the progress of society, high-rise buildings and underground buildings have been found in big cities, And tunnel projects increased greatly, but at the same time in order to save the land, make full use of underground spac
2、e, the deep excavation engineering is increasing. The deep foundation pit engineering is a comprehensive ancient and epoch-making characteristics of geotechnical engineering, because it involves not only the soil mechanical strength and deformation of typical problems it relates to the soil and supp
3、orting structure interaction problems. After the analysis is not difficult to see that the development of foundation pit engineering is a new type of support led to the emergence of new analysis methods, and follow the practice, understanding, practice, understanding the law and gradually matured. I
4、n 1930s, the first in the study the foundation pit engineering Terzaghi and Peake, 60s in Oslo and other places of excavation began to implement the construction monitoring, from 70s onwards, many countries have formulated the guiding and supporting design of foundation pit excavation Design and con
5、struction of the regulations in China. In the early 1980s began to appear a lot of excavation. Before 80s, the domestic high-rise building is one of the few in the basement is a layer of deep foundation pit, but 4 m, often used in slope excavation can solve the problem. By 80s, with a large number o
6、f high-rise building construction two, began to appear in basement excavation depth is generally around 8 m, a few more than 10 m. in 90s, Chinasrapid development of high-rise buildings, but also around the construction of large underground municipal facilities, underground shopping malls, subway st
7、ations, leading to the basement layer gradually increased, the excavation depth of more than 10 m meet the eye everywhere the excavation. 2 deep foundation pit engineering problems Design and construction of foundation pit engineering, both to ensure the whole support structure in the process of con
8、struction safety, control structure and surrounding soil deformation but also to ensure the surrounding environment (adjacent buildings and underground public facilities) safety. Therefore, how to ensure the excavation safety and economical and practical is feasible a very important and urgent issue
9、s in the construction of the modern city. Especially in twentieth Century, with the increasingly high requirements of foundation pit engineering, along with more and more problems. Some problems of deep foundation pit are discussed below:1. problems existing in construction stage The quantity, scale
10、 and distribution of deep foundation pit increase rapidly, and the construction technology of deep foundation pit and monitoring technology in construction field should be improved as soon as possible. Moreover, the construction management is poor and the construction qualification is not strictly l
11、imited. Therefore, many problems should be paid attention to during construction. It is necessary for construction, owners, design and monitoring to cooperate with and cooperate with each other in the excavation of the foundation pit. 1) improper treatment of ground water in foundation pit construct
12、ion In the construction of foundation pit groundwater treatment is a difficult problem, due to differences in soil and groundwater, the excavation construction method is different, especially in the coastal areas with high water level or surface water rich area, medium treatment of groundwater in de
13、ep foundation pit engineering construction is the key to the success of the project. The survey shows that over the past few years, our country deep foundation pit retaining support system failure or safety and environmental problems resulted from the failure of the part about the total project 10%
14、15%, the soft soil with high water table areas up to 20%, in some areas a higher failure rate. These accidents, some very serious consequences, not only to the country caused great the economic losses, but also caused unnecessary casualties, delay and affect the normal life of the residents around t
15、he negative effects, damage the image of construction enterprises. The cause of these accidents a The main reason is the improper treatment of groundwater. So, in the deep foundation pit engineering many failed, because a lot of groundwater in foundation pit construction drainage not dealt with drai
16、nage of the upper soil layer mainly solves the backwater and rain water drainage, including the precipitation of light well point, spray well point and deep well point precipitation. Land subsidence may lower the underground water level that will cause adverse effects on the environment, especially in the deep well dewatering effect. 2) the degree of information construction is not high Due to the geological conditions of deep excavation engineering is complicated, and t
