基坑开挖事故隐患分析与安全工程设计(2)
A foundation pit excavation accident hidden danger analysis and safety engineering design
Design Description: The design targeted at certain Foundation pit excavation. Our urban high-rise buildings and underground space development and utilization of rapid development, more and more number of foundation engineering, foundation engineering accidents in recent years is frequently, construction has become a dangerous part of the project. So the Foundation pit excavation of accident analysis and safety engineering hidden significance.
The design for a subway station pit, located in Yangpu District Planning Changyang Patriotic Road and Road intersection east, east-west layout, the station length 164.4m. Standard segment the main pit depth of approximately 17.5m, width 21.5m, end depth 19.4m, width 24.6m, pit protection class two; 4 subsidiary pit depth of approximately 11m, number 4 partially due to set the cable subsidiary Pit mezzanine depth of about 12.5 m, pit protection are two. Site stations which strata are mainly plastic-like stream silt clay pit deeper, poor geological conditions, and how with the location of underground pipelines, the construction process is sensitive to disturbance and sedimentation. High water table, on the foundation of higher permeability. The design first analyzes the characteristics of the excavation engineering, excavation engineering of excavation engineering overview of the excavation engineering development in our country and our foundation excavation safety status of the status quo, but also analyzes the sources of risk and accident factors, as well as the common pit potential accidents prevention methods.
First, The design has analyzes the characteristics of foundation engineering, the foundation engineering overview of our country, the foundation pit excavation development of our country and our foundation pit excavation engineering construction status of the security situation, but also analyzes the source of excavation engineering and accident risk factors as well as common the pit accidents prevention methods.
Secondly, analysis the causes of accidents of a foundation pit excavation from the three aspects, unsafe behavior, dangerous state of object defects, management defects. Select the most significant effect on the safety of foundation pit excavation from the results of the analysis of the three potential causes of accidents, foundation pit supporting to conduct security engineering. The foundation pit support technology in our country is relatively young, whether design calculations, construction, monitoring or other aspects are in the progress and development process. The excavation engineering characteristics in our country can be summarized as "deep, dense, low five words, that our country pit dig deeper and deeper, engineering geological condition is getting worse, surrounded by built or under construction building material-intensive or close to the municipal road, foundation pit support, but support the low success rate.
Finally, the rationale for deep excavation software for the design, simulation and verification. Rationale for deep excavation supporting software is based on the deep foundation pit supporting technical regulations JGJ120-2012 "and 7 places in Beijing, Shanghai, Tianjin, Guangdong, Shenzhen, Guangzhou, Wuhan specifications as well as the Ministry of Metallurgical industry norms of 10 basis pit for specification. Classic method and Flexibility Act (including the full amount of method and incremental method) were used to complete the cantilever or branched anchored single row of piles, double-row piles, diaphragm walls, steel sheet pile, cement walls (SWM), soil nails walls, natural grading and other forms of support calculation. The calculation includes the earth pressure calculation, support building internal force calculation and reinforcement, anchor and support within the calculation of stability in design, anti-overturning checking, anti-bulge checking, anti-piping checking, checking confined water output illustrated detailed calculations. According to the actual shape of the pit and the last support bolt arrangement of three-dimensional overall.
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