The Cause of Instability and Reinforcement of the Complicated High Slope Drawing near a Deep-Founding Pit

2011 ◽  
Vol 368-373 ◽  
pp. 2022-2026
Author(s):  
Qi Yun Wang ◽  
Jia Sheng Zhang ◽  
Jin Xu
Keyword(s):  
Retaining Wall ◽  
Horizontal Displacement ◽  
Deformation Monitoring ◽  
Deep Soil ◽  
Support Structure ◽  
Foundation Pit ◽  
Technical Data ◽  
Factors Affecting ◽  
Retaining Structure ◽  
Bracing System

The combination of a single row of artificially-dug-up piles and pre-stressed anchor rope was adopted to the foundation pit as the retaining structure,and anchor-plate retaining structure and rubble retaining wall were used as the bracing system for the complicated building slope. In the process of excavation, monitoring has been done to see if any horizontal displacement, deformation of deep soil and crack width take place or any technical data and code dispatch from the demand. Monitoring results show that deformation in some parts of the tops of support structure is larger than the designed warning value some times and the deformation continue to increase in the process of the excavation, and this result in twice dangerous situations in the support structure of the slope. In this paper, the geologic construction of the slope and the situations of the designed support structure and monitoring condition were depicted. The mechanism of the instability of the slope was explained on the basis of comprehensive analysis of deformation monitoring datas. It is concluded that the over-excavation, explosive excavation, rainfall and so on were the factors affecting the stability of the slope. Corresponding emergency measures and reinforcement measures,such as unloading and pre-stress rope, were proposed, which were proved to be highly effective.

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.

Effect of Staged Excavation on Retaining Structure in Soft Soil Area

2012 ◽  
Vol 170-173 ◽  
pp. 633-636 ◽  
Author(s):  
Jie Liu ◽  
Xin Guang Xu
Keyword(s):  
Soft Soil ◽  
Horizontal Displacement ◽  
Structure Type ◽  
Operating Conditions ◽  
Deep Soil ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Retaining Structure ◽  
Geological Conditions

Based on a deep foundation pit in Tianjin, the authors introduced the retaining structure type, surrounding conditions, and the geological conditions of proposed field. According to the engineering characteristics, the excavation was divided into three typical operating conditions. Based on the monitoring of staged excavation of deep foundation pit, analysis on horizontal displacement, deep soil displacement, column settlement and bracing axial force was carried out. The general rules of the deformation and internal force of retaining structures induced by staged excavation were given, which will provide the references for similar engineering.

Application of Mc Composite Retaining Structure in the Silt Soil Foundation

2013 ◽  
Vol 353-356 ◽  
pp. 341-346
Author(s):  
Ying Cheng ◽  
Ai Zhao Zhou
Keyword(s):  
Retaining Wall ◽  
Ground Surface ◽  
Bending Moment ◽  
Horizontal Displacement ◽  
Foundation Pit ◽  
Wall Width ◽  
Obvious Effect ◽  
Retaining Structure ◽  
Supporting Structure ◽  
Soil Foundation

This pape combined with the engineering example of a supporting muddy soil foundation pit,used the finite element numerical analysis method, discussed on mechanical deformation characteristics of the cement-soil pile and concrete pile composite retaining structure (MC pile for short ) , Including the effect of section parameters of MC pile on the horizontal displacement of supporting structure, settlement of ground surface and bottom heave. The results show that, MC pile composite retaining structure are beneficial to control the deformation of foundation pit, and increase the stability of foundation pit; M pile retaining wall width to reduce the deformation of the retaining structure has obvious effect, which increase the width of wall can decrease the bending moment ,inclination deformation of supporting structure and lowe bottom heave and surface settlement. Moreover, in the same wall width, there is no C pile to control the deformation of the retaining structure and deformation of the foundation also has a great role.

Monitoring and Analysis for the Deformation of SMW Retaining Structures in Subway Station

2014 ◽  
Vol 580-583 ◽  
pp. 1249-1253
Author(s):  
Jiang Tao Xia ◽  
Shao Fei Zhang ◽  
Hua Rong Shen ◽  
Ze Jun Liu ◽  
Shi Qing Huang
Keyword(s):  
Early Stage ◽  
Horizontal Displacement ◽  
Ground Subsidence ◽  
Subway Station ◽  
Deep Soil ◽  
Foundation Pit ◽  
Retaining Structures ◽  
Soil Mixing ◽  
Wall Structures ◽  
Soil Excavation

The monitoring is carried out for deformation of the soil-mixing-wall structures used in Baijihu subway station. The horizontal displacement of deep soil is obtained, as well as the ground subsidence around the edges of the foundation pit. Their variation rules under the influence of some factors, such as soil excavation and support settings etc, is analyzed. The results show that during the process of SMW construction, it is necessary to monitor the horizontal displacement of deep soil and the ground subsidence around the edges of the foundation pit, especially during the early stage of excavation.

scholarly journals Full-Scale Field Test On Retaining Structure Enhanced With Soil Nails And Prestressed Anchors

2021 ◽  
Author(s):  
Hui Wang ◽  
Jian-hua Cheng ◽  
Yuan-cheng Guo
Keyword(s):  
Rational Design ◽  
Horizontal Displacement ◽  
In Situ Tests ◽  
Foundation Pit ◽  
Soil Nails ◽  
Soil Nail ◽  
Retaining Structure ◽  
Prestressing Force ◽  
Materials Used ◽  
Unbonded Length

Abstract Retaining structure enhanced with soil nails and prestressed anchors is found good at constraining the horizontal displacement and therefore ensuring the stability of the foundation pit during excavation. Based on these advantages, such retaining structure is widely used in foundation excavation practice. This paper presents results of a series of in-situ tests conducted to investigate the mechanical behaviors of retaining structure enhanced with soil nails and prestressed anchors. Behaviors of three different retaining structures enhanced with i) soil-nails; ii) soil-nails and prestressed anchors without unbonded part; iii) soil-nails and prestressed anchors with a 2.5m unbonded length, were monitored during staged excavation to investigate the influences of i) the prestressing force and ii) unbonded length of the prestressed anchors on the performance of the entire retaining system. It was found that the affecting the stress and deformation of composite retaining system, which is in agreement with the other published results in the literature. The variation of the magnitude and distribution of soil nail force responding to the anchor prestressing force however showed no systematic trend. The unbonded length of anchors, which is suggested to be the main factor affecting the structural stability in dense materials in the literature, is found to have little influence in loose fill materials used in this study. Studies presented in this paper are useful for the rational design and serviceability analysis of the composite soil-nailed retaining structure enhanced with prestressed anchors.

scholarly journals Impact Analysis of Support Structure of Unsymmetrical Loading Deep Foundation Pit Adjoining Highway

2015 ◽  
Vol 9 (1) ◽  
pp. 463-470
Author(s):  
Donglin Wang ◽  
Lei Wang
Keyword(s):  
Impact Analysis ◽  
Simulation Analysis ◽  
Great Influence ◽  
Horizontal Displacement ◽  
Friction Angle ◽  
Deep Foundation ◽  
Support Structure ◽  
Foundation Pit ◽  
Load Effect ◽  
Deep Foundation Pit

The air shaft deep foundation pit 6 is influenced by subgrade unbalance loading of highway 312, specifically its deep horizontal displacement of supporting piles and subgrade settlement of expressway 312 under unsymmetrical load effect. This paper carries out construction monitoring and numerical simulation analysis and gives a detailed study on the influenced factors of support structure deformation. Calculation results show that subgrade unsymmetrical load has a great influence on deep horizontal deformation of supporting piles. The maximum horizontal displacement at the bias side is about three times more than non-bias side’s; when the distance of subgrade to foundation pit is the same as the depth of excavation, the influence of subgrade on pit can be ignored; as the cohesion and internal friction angle increases, the horizontal displacement of fender piles decreases. However, enlarging the embedded depth of supporting piles has no significant influence on the stability of foundation pit.

scholarly journals Numerical Simulation of Deep Foundation Pit Construction under Complex Site Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Huifen Liu ◽  
Kezeng Li ◽  
Jianqiang Wang ◽  
Chunxiang Cheng
Keyword(s):  
Numerical Simulation ◽  
Ground Surface ◽  
Reference Value ◽  
Horizontal Displacement ◽  
Deformation Monitoring ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Ground Surface Settlement ◽  
Stress And Deformation

Based on the deep foundation pit project of Laoguancun station of Wuhan rail transit line 16 and according to the engineering characteristics of the construction conditions and the site surrounding the environment, the method of combining field monitoring and finite element numerical simulation is adopted to analyze the law of stress and deformation of the deep foundation pit during excavation and support construction; it includes the horizontal displacement of the underground diaphragm wall, supporting axial force, and the ground surface settlement, which can be compared with measured data. Finally, some suggestions for monitoring and construction of the deep foundation pit in the subway station have been put forward and have certain reference value and practical guiding significance for the design and construction of similar engineering projects. The deformation monitoring of the retaining structure at the middle of the long side of the foundation pit should be strengthened during the construction process.

scholarly journals Study on the earth pressure of a foundation pit adjacent to a composite foundation with rigid-flexible and long-short piles

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251985
Author(s):  
Yuancheng Guo ◽  
Shaochuang Gu ◽  
Junwei Jin ◽  
Mingyu Li
Keyword(s):  
Three Dimensional ◽  
Earth Pressure ◽  
Friction Angle ◽  
Element Model ◽  
Composite Foundation ◽  
Deep Soil ◽  
Foundation Pit ◽  
Testing Procedures ◽  
Retaining Structure ◽  
Lateral Earth Pressure

Model tests were performed to investigate the lateral earth pressure acting on the retaining structure adjacent to both natural ground (NG) and composite foundation (CFRLP), which were supported with rigid-flexible and long-short piles. Two testing procedures, namely, applying a load to the foundation and rotating the retaining structure along its toe, were considered. The results indicate that the additional lateral earth pressure acting on the retaining structure adjacent to the CFRLP is less than that of the NG in the depth of the reinforcement area strengthened by flexible piles. Compared with NG, the CFRLP yielded a smaller normalized height of application of the lateral earth pressure, suggesting that the CFRLP blocked the horizontal diffusion of the load and had a strong ability to transfer the surcharge load to the deep soil. When rotating the retaining structure, the lateral earth pressure acting on the upper part of the retaining structure experienced limited reduction once the displacement at the top of the retaining structure was greater than 8 mm, whereas the pressure acting on the lower part of the retaining structure continued to decrease with increasing displacement. In addition, a three-dimensional finite element model (FEM) was used to investigate the influence of the pile parameter and the wall-soil friction angle on the additional lateral earth pressure.

The Study of Deformation Law of a Super Deep Foundation Pit in the Process of Dismantling the Inner Support

2014 ◽  
Vol 638-640 ◽  
pp. 614-619
Author(s):  
Bo Liu ◽  
Qing Nan Liu ◽  
Yi Yan Zhao ◽  
Bing Hui Chen
Keyword(s):  
Horizontal Displacement ◽  
Deformation Monitoring ◽  
Maximum Point ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Supporting Structure ◽  
The Earth ◽  
Earth Pressures ◽  
Deformation Law

Dismantling the inner support of deep foundation pit is a risk point.It is of great importance to guarantee the safety of foundation pit when removing the inner support, and the deformation monitoring and analysis in the process of dismantling inner support is crucial. In this paper, a super deep foundation pit engineering as the research background.Through monitoring and analyzing the law of a deep horizontal displacement of the supporting structure,ground settlement, vertical settlement and axial force of support in the process of support demolition,which can be obtained that: the settlement of surface ground around the foundation shows spatial and temporal clearly and the distribution of deep horizontal displacement of supporting structure is similar to the parabolic which the maximum point constant upward shift with supporting continuous removed.Soil pressure of supporting shared with support removing process is changing, and the earth pressures support sharing is increasing. From the monitoring results, the demolition scheme is reasonable and effective and meets the requirements of design and environment.

The Relationship between Retaining Wall Deformation and Earth Pressure in Deep Excavation

2012 ◽  
Vol 446-449 ◽  
pp. 1690-1695
Author(s):  
She Qin Peng ◽  
Qi Hua Zhao ◽  
Zi Yang Chen
Keyword(s):  
Retaining Wall ◽  
Earth Pressure ◽  
Suspension Bridge ◽  
Deep Excavation ◽  
Foundation Pit ◽  
Retaining Structure ◽  
Pressure Calculation ◽  
Wall Deformation ◽  
Pit Depth ◽  
The Relationship

Earth pressure may change with retaining wall deformation in the process of deep excavating. But how? The answer can be very important to the safety of retaining system. Using monitoring data of north anchor foundation pit of Runyang suspension bridge, this paper studied retaining structure and soil interaction. Find the relationship between retaining wall deformation and earth pressure in deep excavation. In this case, earth pressure increased with wall deformation upward the depth of 18m and decreased with wall deformation down below. A regression equation about foundation pit depth and ratio of earth pressure and wall deformation was established. Then give a simplified earth pressure calculation method considering retaining wall deformation.

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