scholarly journals Numerical Analysis on the Performance of the Underwater Excavation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Bo Li ◽  
Cangqin Jia ◽  
Guihe Wang ◽  
Jun Ren ◽  
Gaofeng Lu ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Retaining Wall ◽  
Lateral Wall ◽  
Surface Settlement ◽  
Design Parameters ◽  
Analysis Model ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Wall Deflection ◽  
Total Settlement

Based on the Yongdingmen Station of Beijing Metro, the underwater excavation method for deep foundation pit was introduced. This study constructed a numerical analysis model to analyze the performance of surface settlement and lateral wall deflection in the process of underwater excavation. Results showed that this method was better to control the surface settlement and lateral wall deflection compared with other dewatering excavations. In detail, most of the surface settlement was caused during the dry excavation stage and dewatering excavation stage while the deflection caused by underwater excavation only accounted for about 10% of the total settlement. Besides, the maximum settlement occurred 0.25∼0.5 H e behind the retaining wall and the value was 0.04% H e . Similar to the result of the surface settlement, most of the lateral wall deflection had been completed before the underwater excavation, which only caused about 7% of the total deflection. The maximum wall deflection and its location were approximately 0.06% H e and 0.5 H e , respectively. Moreover, a series of 3D numerical analyses were studied on the design parameters of the underwater excavation method. This study can be used as a reference for general performance and structural design of foundation pits with underwater excavation.

Three-Dimensional Numerical Analysis of Excavation and Support of Deep Foundation Pit

2012 ◽  
Vol 446-449 ◽  
pp. 1922-1926
Author(s):  
Chang Zhi Zhu ◽  
Xing Lian Zheng
Keyword(s):  
Numerical Analysis ◽  
Finite Difference ◽  
Three Dimensional ◽  
Horizontal Displacement ◽  
Test Results ◽  
Deep Excavation ◽  
Analysis Model ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit

Based on a project, a numerical analysis model was established by the finite difference program and the process of the deep excavation and support was simulated by computer, the distribution of the horizontal displacement and settlement of the top of slope of the slope soil were obtained. The simulation result was consistent with the test results. It shows that the method of numerical analysis can be used to the simulation of the excavation and support of Deep Foundation Pit, and it will provide the basis for the design and construction of practice project.

scholarly journals Analysis on Deformation and Stress Characteristics of a Multibraced Pit-in-Pit Excavation in a Subway Transfer Station

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Xin Shi ◽  
Chuanxin Rong ◽  
Hua Cheng ◽  
Linzhao Cui ◽  
Bin Wang ◽  
...  
Keyword(s):  
Ground Surface ◽  
Lateral Wall ◽  
Surface Settlement ◽  
Lateral Deformation ◽  
Monitoring And Control ◽  
Foundation Pit ◽  
Wall Displacement ◽  
Transfer Station ◽  
Ground Surface Settlement ◽  
Total Settlement

As an important part of subway transfer station construction, pit-in-pit (PIP) excavation has always been a key object of monitoring and control. In this study, taking the PIP excavation project of Hefei metro line 4 and line 7 transfer station as the background, combined with on-site monitoring and numerical simulation, the variation law of lateral wall displacement, ground surface settlement, and strut force during the PIP excavation were analyzed. The results showed that the maximum lateral deformation of the pile caused by the excavation of the external pit accounted for 80%–90% of the total deformation and the surface settlement accounted for 70% of the total settlement. The excavation of the inner pit only made the maximum lateral wall displacement of the outer pit and the surface settlement behind the wall increase slightly, the growth rate tended to zero, and the maximum lateral deformation depth was all above the excavation surface, which indicated that, for this project, the inner excavation had little effect on the outer pit retaining structure. In addition, the increased exposure time of the soil at the bottom of the pit and the presence of the corner effect will cause the further development of the structure displacement and the surface settlement. Based on strut force measurements, using the tributary area load distribution procedure, it was obtained that 0.3γHe was used as the upper limit index of strut force in the region, where γ is the weight of the soil and He is the excavation depth of the foundation pit. The research conclusions were helpful for the construction and sustainable development of the PIP project.

Numerical Analysis of the Construction Influence of Deep Foundation Pit on Adjacent Open Trench Tunnel

2011 ◽  
Vol 94-96 ◽  
pp. 1902-1907
Author(s):  
Cong Shi Wu ◽  
Wei Da Shen ◽  
Gong Liu
Keyword(s):  
Numerical Analysis ◽  
Analysis Model ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Building Foundation ◽  
Adjacent Building ◽  
Special Project ◽  
Open Trench ◽  
Construction Optimization

The open trench D ramp of Yingpanlu Xiangjiang tunnel in Changsha and the adjacent building foundation pit construction were excavated almost at the same time. The minimum distance between the two pits was only 8 meters, and keeping both projects safe working became difficult in engineering. Therefore a special project example of numerical analysis model was established, which can simulate the whole construction course. The construction stress was analyze by combining with the soil and retaining structures displacement, and the results were compared with the actual measured data to provide a reference to the design and construction optimization.

On Numerical Simulation of the Stepped Soil-Nail Wall

2013 ◽  
Vol 353-356 ◽  
pp. 692-695
Author(s):  
Chang Zhi Zhu ◽  
Quan Chen Gao
Keyword(s):  
Numerical Simulation ◽  
Numerical Analysis ◽  
Internal Force ◽  
Numerical Results ◽  
Analysis Model ◽  
Foundation Pit ◽  
Soil Nails ◽  
Soil Nail ◽  
Soil Nail Wall ◽  
Design And Construction

Based on an Engineering Example which was supported by the stepped soil-nail wall, a numerical analysis model was established by FLAC3D,and the process of the excavation and supporting was simulated, and the numerical results of the soil nails internal force and foundation pit deformation were obtained. The simulated result was consistent with the measured results. It shows that the method of FLAC3D numerical analysis can be used to the numerical analysis of foundation pit excavation and supporting, and it will provide the basis for the design and construction of practice project.

Research on Soil Nailing Method for Large Foundation Pit Treatment

2014 ◽  
Vol 638-640 ◽  
pp. 538-541
Author(s):  
Zi Mao Peng
Keyword(s):  
Side Wall ◽  
Design Parameters ◽  
Soil Pressure ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Building Foundation ◽  
Backfill Soil ◽  
Soil Complex ◽  
Large Building

Based on the introduction of the characteristics of the supporting project of a large building foundation pit, the paper analyzed the main reasons for side wall collapse and pile fracture, including leakage water in the backfill soil, complex geological environment and unreasonable soil pressure value, low safety factor and improper design parameters, and then respectively proposed three kinds of treatment schemes for side wall sliding and pile breaking, landslides and other dangers. Finally, tracking observation showed that the satisfactory effect can strongly verify the suitability and validity of the main control parameters for the deformation of deep foundation pit, which may provide reference for the design and construction of similar projects.

Deep Foundation Pit Monitoring Based on CX-3C Inclinometer

2014 ◽  
Vol 484-485 ◽  
pp. 404-407 ◽  
Author(s):  
Qing Guo Ren ◽  
Guang Zhang ◽  
Xiao Guang Yue ◽  
Wen Cheng Liao
Keyword(s):  
Vertical Profile ◽  
Retaining Wall ◽  
Horizontal Displacement ◽  
Displacement Monitoring ◽  
Deep Soil ◽  
Security Risks ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Main Factors

Deep soil horizontal displacement monitoring can measure the retaining wall board, row piles deformed shape, reflect the foundation on the vertical profile of horizontal displacement with depth changes in the law, predict foundation stability and security risks. Combined with Wuhan WANGJiaDun Pit Engineering, this article introduce CX-3C inclinometer work principle, put forward the calculated optimization measures of inclinometer, and analysis the main factors which should be considered to arrange the measuring points.

scholarly journals Displacement Monitoring during the Excavation and Support of Deep Foundation Pit in Complex Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Zhouqiang Li
Keyword(s):  
Axial Force ◽  
Time History ◽  
Horizontal Displacement ◽  
Underground Water ◽  
Surface Settlement ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Anchor Cable ◽  
The North

Taking a super large deep foundation pit project as an example, the horizontal displacement of crown beam and driveway, surface settlement, axial force of anchor cable, and underground water level in the construction process of the foundation pit are dynamically monitored and analyzed. The excavation deformation rule of the deep foundation pit and the influence of excavation on surrounding buildings are analyzed. The results show that, with the excavation of the foundation pit, the crown beam and driveway of the foundation pit incline towards the direction of the pit and eventually tend to be stable. The variation of axial force of the prestressed anchor cable in the first layer of the foundation pit is basically consistent with the variation of horizontal displacement time history. The variation trend of the groundwater level at each side of the foundation pit is different but tends to be stable in a short time. In the whole monitoring period, the cumulative settlement value of each area of the foundation pit is within the controllable range, but the surface settlement of the north side of the foundation pit and a surrounding building has not reached stability, so it is suggested to extend the monitoring time of settlement in the relevant area.

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