Analysis on Excavation Procedure in Large Soft Soil Foundation Pit of Shanghai Expo Axis

2011 ◽  
Vol 243-249 ◽  
pp. 2909-2914
Author(s):  
Xiang Yuan ◽  
Quan Mei Gong ◽  
Shun Hua Zhou
Keyword(s):  
Numerical Calculation ◽  
Soft Soil ◽  
Model Tests ◽  
Diaphragm Wall ◽  
Foundation Pit ◽  
Centrifuge Model ◽  
Wall Deformation ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Centrifuge Model Tests

On the basis of the large soft soil foundation pit of Shanghai Expo axis and the Section 1 of underground complex project, this paper proposes the appropriate excavation procedure according to the results obtained by using centrifuge model tests and time hardening creep model, which uses ANSYS to compute foundation pit deformation caused by different excavation timeline, sequence and longitudinal excavation width of remained berm. The results of numerical calculation were approximately close to the horizontal displacement of the underground diaphragm wall measured both on site and from centrifuge model tests, so numerical calculation could well reflect the deformation behavior of excavation. The study also showed that more than 80% of underground diaphragm wall deformation caused by soil creep occurred within 60 days after the remained berm being excavated. In order to decrease the deformation, it would be useful to conduct plate structures as soon as the remained berm started being excavated. Remained berm and middle plate had good control over underground diaphragm wall deformation. When the remained berm was excavated by jumpily digging method, it would be advisable to firstly excavate the vicinity of underground diaphragm wall where there were no required protected objects nearby. The longitudinal excavation width of remained berm was proposed to be 20 meters in the north part and 30 meters in the south part.

scholarly journals Study on Supporting Structure Performance of Deep Soft Soil Foundation Pit near Sea under Waves, Tides, Vibration, and Unbalanced Loads

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Junsheng Chen ◽  
Chen Lin ◽  
Shuzhuo Liu ◽  
Haihong Mo
Keyword(s):  
Mechanical Performance ◽  
Soft Soil ◽  
Offshore Structure ◽  
Foundation Pit ◽  
Supporting Structure ◽  
Vibration Loads ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Unbalanced Loads ◽  
Offshore Foundation

In addition to the vibration loads caused by offshore structure construction, the offshore foundation pit can also be affected by additional hydraulic loads such as waves, tides, and typhoons, hindering our understanding of the mechanical performance of the foundation pit supporting structure. In order to illuminate this mechanical performance under waves, tides, hammering, and unbalanced loads, this paper analyzed the supporting structure with theoretical and numerical simulations. The results were verified with field monitoring data. Moreover, the influences of loads, including construction vibration loads and unbalanced loads, on structure and soil were discussed. By applying these results to the engineering design, this research could provide a reference for studying mechanical properties of relevant supporting structures and the construction of offshore foundation pits.

scholarly journals Deformation Law of the Diaphragm Wall during Deep Foundation Pit Construction on Lake and Sea Soft Soil in the Yangtze River Delta

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Yuan Mei ◽  
Dongbo Zhou ◽  
Xueyan Wang ◽  
Liangjie Zhao ◽  
Jinxin Shen ◽  
...  
Keyword(s):  
Soft Soil ◽  
Yangtze River Delta ◽  
Diaphragm Wall ◽  
Lateral Deformation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Deformation Law ◽  
Wall Deformation ◽  
Subway Stations

So far, there have been a large number of diaphragm walls in the Yangtze River Delta as engineering examples of deep foundation pit maintenance structures in subway stations, but there is a lack of systematic research and summary on the deformation characteristics of ground connecting walls. This study aimed to clarify the deformation law of the diaphragm wall during the excavation of a deep foundation pit in a soft soil region. Based on the monitoring data of the diaphragm wall of the deep foundation pit of the Hangzhou metro station, the monitoring data of the deep foundation pits of 15 subway stations in Shanghai and Ningbo cities around Hangzhou were considered. Grouping and classification methods were used to analyze the similarities and differences in the deformation characteristics of the diaphragm wall in the three regions. The results indicate the following: the maximum lateral deformation of the diaphragm wall in Hangzhou increases linearly with the relative depth of the maximum lateral deformation. The maximum lateral deformation of the foundation pit in Hangzhou is 0.072% H∼0.459% H, with a mean of 0.173% H. The wall deformation in Hangzhou varies significantly with the depth of the foundation pit, but the influence of the depth of the foundation pit on the wall deformation is considerably less than that in Shanghai and Ningbo. The corresponding position of the maximum lateral deformation in the excavation depth increases linearly with the excavation depth of the foundation pit, and the corresponding position of the lateral deformation of the diaphragm wall in Shanghai is more affected by the excavation depth of the foundation pit. The lateral deformation of the diaphragm wall increases rapidly in the range of 0 H–0.5 H, and the maximum lateral deformation occurs at 0.5 H–1.1 H.

The Application of Anchor Block in Large Soft Foundation Pit Excavation

2012 ◽  
Vol 170-173 ◽  
pp. 520-524
Author(s):  
Chi Ma ◽  
Guo Nan Liu ◽  
Yue Ying Liang
Keyword(s):  
Soft Soil ◽  
Rail Transport ◽  
Foundation Engineering ◽  
Foundation Pit ◽  
Soft Foundation ◽  
New Ideas ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Improved Design ◽  
Anchor Block

Based on pit excavation of Shenzhen Airport Rail transport hub project, combined with anchorage stress characteristics, difficulties was studied and numerical calculation for the envelope structure was undertaken. The successful application of design provides new ideas, improved design methods for super soft soil foundation engineering, which can greatly promote the application and development of anchor block in soft foundation excavation.

Study on the Deformation of Retaining Structure of Pit-in-Pit Excavation

2011 ◽  
Vol 243-249 ◽  
pp. 2903-2908 ◽  
Author(s):  
Jun Shuai Huo ◽  
Juan Chen ◽  
Quan Mei Gong ◽  
Shun Hua Zhou
Keyword(s):  
Numerical Analysis ◽  
Natural History ◽  
Critical Distance ◽  
Model Tests ◽  
Diaphragm Wall ◽  
Retaining Structure ◽  
Centrifuge Model ◽  
Shanghai Museum ◽  
Diaphragm Walls ◽  
Centrifuge Model Tests

There are more and more pit-in-pit excavations in cities, which include inner pit and outer pit. Owing to the inner pit excavation, pit-in-pit problem aroused and brought about accidents. For this reason, based on the co-construction, deep, and large pit-in-pit of Shanghai Museum of Natural History and Metro Line 13, the excavation influence between inner pit and outer pit was analyzed. The deformation of underground diaphragm wall under the condition of three different distances between outer pit and inner pit were compared through centrifuge model tests. Then, the effect of excavation width of outer pit on underground diaphragm walls was researched through numerical analysis. Results show that the deformation of outer underground diaphragm wall increased with the excavation width of outer pit, for the inner pit, the opposite was true. The critical influence distance between outer pit and inner pit was within 22 meter and 24 meter. According to the critical distance, the area adverse to excavation pit stability was identified.

Selection Analysis of Enclosure Structure for Deep Foundation Pit under Complicated Geological Conditions

2012 ◽  
Vol 446-449 ◽  
pp. 1400-1403
Author(s):  
Qi Hu ◽  
Sheng Ming Luo ◽  
Zhu Jin Jiang
Keyword(s):  
Soft Soil ◽  
Structure Design ◽  
Soil Conditions ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Structure Selection ◽  
Geological Conditions ◽  
Soil Foundation ◽  
Soft Soil Foundation

By comprehensive consideration of soil conditions, geometric shape of deep foundation pit and many other kinds of factors, enclosure structure design needs to select optimal supporting and enclosure system with safety, economy and construction feasibility. On case study of enclosure structure selection about typical soft soil foundation, this paper researches effects of force- deformation of enclosure structure by brace layout, and of economy and construction feasibility. The research results may offer reference for similar projects.

A Comprehensive Analysis of Soft Soil Foundation Pit Accident

2013 ◽  
Vol 405-408 ◽  
pp. 3-9 ◽  
Author(s):  
Hui Hu ◽  
Lian Sheng Tang ◽  
Xing Li Lin ◽  
Fei Kuang
Keyword(s):  
Soft Soil ◽  
Comprehensive Analysis ◽  
Accident Investigation ◽  
Foundation Pit ◽  
Factors Affecting ◽  
Pullout Resistance ◽  
Supporting Structure ◽  
Soil Foundation ◽  
Soft Soil Foundation ◽  
Design Factors

Factors affecting the supporting structure in a soft soil foundation pit are analyzed in this paper. Based on the information obtained from accident investigation, design factors and construction factors, such as insufficient embedded depth of pile and insufficient anchor pullout resistance, are discussed in detail. The analysis and conclusions can serve as a good reference for similar projects design and construction.

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