Simplified Method for Estimating the Inner Support and Internal Force through Stand Column Uplift of Foundation Pit in Soft Soil

2014 ◽  
Vol 580-583 ◽  
pp. 474-480
Author(s):  
Yan Liu ◽  
Jun Yan Liu ◽  
Tao Liu
Keyword(s):  
Soft Soil ◽  
Influence Factors ◽  
Bending Moment ◽  
Internal Force ◽  
Calculation Model ◽  
Practical Calculation ◽  
Foundation Pit ◽  
Excavation Process ◽  
Simplified Calculation ◽  
Main Influence

In the excavation process of Foundation Pit in Soft Soil area, it will cause the large uplift of stand column, and may cause the instability and failure of foundation pit in case of being serious; but the additional internal force of support system caused by the uplift and sinking of stand column currently has no practical calculation model in the foundation pit design. This article discusses the reason and mechanism for uplift of stand column in the foundation pit, proposes the simplified calculation method of estimating the additional bending moment of inner support through uplift of stand column in allusion to two main influence factors of bottom heave and vertical load caused by the excavation of foundation pit, inversely calculates the permissible additional bending moment of inner support based on this, verifies by combining the monitoring data for uplift of stand column in the actual project, and finally, further proposes the project measures corresponding to the uplift of stand column, hoping to provide beneficial reference for the similar project.

Comparative Analysis of the Influence of Different Construction Technology for Excavation on Adjacent Tunnels

2014 ◽  
Vol 638-640 ◽  
pp. 884-887
Author(s):  
Yong Gang Du ◽  
Jing Cao ◽  
Zu De Ding
Keyword(s):  
Lateral Displacement ◽  
Internal Force ◽  
Calculation Model ◽  
Construction Technology ◽  
Tunnel Structure ◽  
Lateral Deformation ◽  
Foundation Pit ◽  
Engineering Construction ◽  
Excavation Process ◽  
Calculation Results

Based on the project of a foundation pit engineering adjacent to existing tunnel of Kunming metro line 1, a 3D calculation model is established in consideration the interaction of foundation pit support structures, tunnel structure and soil. In this paper, the authors have simulated the foundation pit excavation process in three conditions, and analyzed the changing laws of the lateral displacement and internal force of the tunnel induced by adjacent excavation under different conditions. Calculation results show that the distributions and the values of the displacement and internal force of the tunnel are obviously different under three different construction technologies, and the “jump dig” is the optimum excavation scheme due to the restriction in the excavation of foundation pit, and the lateral deformation of tunnel structure is smallest in this condition. The conclusion can provide a theoretical basis for similar excavation engineering construction.

scholarly journals Internal Force on and Deformation of Steel Assembled Supporting Structure of Foundation Pit under Thermal Stress

2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Bending Moment ◽  
High Strength ◽  
Element Model ◽  
Internal Force ◽  
Foundation Pit ◽  
Dimensional Finite Element ◽  
Influence Of Temperature On ◽  
Scale Experiment ◽  
Three Dimensional Finite Element

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.

Study on Effect of Excavation Depth on Internal Force of Retaining Structure of Arc Row Piles with Arc Ring Beam on the Pile Top

2014 ◽  
Vol 919-921 ◽  
pp. 762-768
Author(s):  
Zhi Wei Zhang ◽  
Rong Gui Deng ◽  
Ze Shuo Chen
Keyword(s):  
Internal Force ◽  
Calculation Model ◽  
Structure Calculation ◽  
Foundation Pit ◽  
Engineering Research ◽  
Retaining Structure ◽  
Body Distribution ◽  
Practical Engineering ◽  
Set Up ◽  
Deformation Compatibility

In order to control deformation of foundation pit effectively and guarantee safety of building around, utilizing the stress characteristics of arch, use the new spatial retaining structure of arc row piles with arc ring beam on the pile top. The arc ring beam can provide constraint to pile top, so internal force of pile body distribution is uniform, and improve the integrity stability of piles. The ring beam with compression mainly can give use of high compression capability of concrete. According to the high order statically indeterminate characteristics of the retaining structure, calculation model of ring beam and pile respectively is established by the redundant forces between beam and pile top. By using deformation compatibility to set up flexibility equation of the retaining structure, and solve the redundant forces, then calculate the internal force and displacement of ring beam and piles. Through calculating the practical engineering, research the effect of excavation depth on internal force and displacement of piles and the arc ring beam on the pile top.

Study on the Influence of the Shield Tunnel Deformation Due to Excavation of Foundation Pit with Field Data

2012 ◽  
Vol 446-449 ◽  
pp. 1808-1812
Author(s):  
Jiang Shu Ding ◽  
Yao Qiang Xian ◽  
Tian Jun Liu
Keyword(s):  
Stress State ◽  
Field Data ◽  
Influence Factors ◽  
Shield Tunnel ◽  
Deep Excavation ◽  
Foundation Pit ◽  
Metro Tunnel ◽  
Main Influence

The deep excavation of the foundation pit adjacent to the metro tunnel will change the stress state of the neighboring soil. And the deformation of tunnel will be induced which will cause impair to daily operation and the safety of metro tunnel. According to the practice of deep excavation neighboring the metro tunnel in Guangzhou, the main influence factors of deformation and stress of tunnel will be analyzed based on exaction conditions and field data. The conclusions will be benefit to similar projects.

Internal Force and Deformation Analysis of Pile-Brace Support Structure of Foundation Pit Considering Deformation Compatibility

2011 ◽  
Vol 90-93 ◽  
pp. 446-452
Author(s):  
Chang Jie Xu ◽  
Zhi Yuan Luo
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Internal Force ◽  
Deformation Analysis ◽  
Support Structure ◽  
Foundation Pit ◽  
Simplified Calculation ◽  
Deformation Compatibility ◽  
Horizontal Displacements ◽  
Element Method

For the current simplified calculation of pile-brace support structure can not calculate the displacements of pile and brace, the authors try to start from the deflection differential equation of beam on elastic foundation, considering the deformation compatibility of pile and brace, and obtains the internal forces and displacements of pile by using Finite Difference Method. Meanwhile, Finite Element Method is used to analyze and calculate the horizontal displacements of pile. The results show that the values obtained by this article are closer to the measured values than that obtained by Finite Element Method. The method is accurate, reliable and simple. Besides, this author also analysis the different horizontal displacements of pile under different parameter conditions of support structure, which can provide some valuable suggestions for the design of foundation pit.

Analysis of Internal Force and Deformation for Pit Retaining Structure by Considering the Interaction of Pile Stiffness

2013 ◽  
Vol 838-841 ◽  
pp. 397-401
Author(s):  
Ming Li ◽  
Ren Wang Liang
Keyword(s):  
Finite Difference ◽  
Engineering Design ◽  
Axial Force ◽  
Influence Factors ◽  
Bending Moment ◽  
Internal Force ◽  
Equivalent Stiffness ◽  
Deep Excavation ◽  
Retaining Structure ◽  
Design Software

In this paper, taking one deep excavation engineering as an example, modeling by the FLAC3D finite difference software, combining with the Lizheng deep excavation supporting design software, taking the equivalent stiffness of combination pile as 2.300-4.789(10-2m3), and analyzing the pile body bending moment, anchor axial force and pit deformation by considering interaction of pile stiffness. In addition, in this paper the influence factors of pile stiffness has been discussed, and provides a reference for the engineering design.

scholarly journals Analysis for bearing performance and construction mechanical behavior of supporting structure for the large cross-section tunnel by half bench CD method

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255511
Author(s):  
Rui Zhao
Keyword(s):  
Cross Section ◽  
Mechanical Characteristics ◽  
Internal Force ◽  
Calculation Model ◽  
Large Cross Section ◽  
Support Structure ◽  
Supporting Structure ◽  
Bending Strain ◽  
Excavation Process ◽  
Deformation Distribution

Based on the engineering practice of large cross-section highway tunnel, this paper reveals the space-time coordinated evolution law of the construction mechanical characteristics and deformation distribution of the support structure in the construction by half bench CD method through field test. At the same time, the mechanical response calculation model of the supporting structure in the partial excavation is constructed, and the mechanical characteristics of the support structure in the partial excavation process are analyzed by above mechanical calculation model. Then, the mechanical and deformation distribution of the feet-reinforcement bolt in the steel frame—foot-reinforcement bolt combined support system is analyzed under different levels of surrounding rock load and different structural parameters of the feet-reinforcement bolt. The research results show that: (1) The internal force of the supporting structure changes most obviously during the excavation of Part Ⅰ, Part Ⅱ and Part Ⅲ, and the internal force of the support structure gradually tends to be stable after a slight increase in the excavation of Part Ⅳ and Part Ⅴ; (2) The horizontal deformation and vertical deformation of the support structure mainly occur in the excavation process of Part Ⅰ, Part Ⅱ and Part Ⅲ, and the excavation of Part Ⅳ and Ⅴ has little effect on the deformation response of the structure. The vertical displacement of the supporting structure is larger than the horizontal displacement, and the dynamic response of the temporary diaphragm structure during tunnel excavation is shrinkage-expansion-shrinkage-expansion; (3) The bending strain of each measuring point decreases with the increase of the distance from the loading point, and the bending strain of section 1 and section 2 is much larger than that of the other three sections; (4) With the increase of the angle, the section position with strain close to 0 gradually moves to the deeper position of the bolt, and the axial strain of each section on the bolt gradually changes from positive strain to negative strain.

Comparative Study on Calculation Model of Hydraulic Tunnel Lining Structure between Beam Element and Solid Element

2013 ◽  
Vol 405-408 ◽  
pp. 1340-1345
Author(s):  
Jing Jing Zhang ◽  
Jun Deng ◽  
Kai Zhang ◽  
Cheng Huang
Keyword(s):  
Internal Force ◽  
Beam Element ◽  
Calculation Model ◽  
Tunnel Lining ◽  
Practical Calculation ◽  
Solid Element ◽  
Beam Analysis ◽  
Lining Structure ◽  
Calculation Results ◽  
The Right

According to the standard Specification for Design of Hydraulic Tunnels (DL/T 5195-2004), the free-flow tunnel lining structure should be calculated with beam element of finite element method that based on structural mechanics. However, the practical calculation shows that when the lining structure reaches a certain thickness, the beam element calculation results are no longer accurate. Combining with the engineering example, stress and internal force of lining structure with different thickness were calculated by using beam3 beam element and the solid65 element respectively in frame beam analysis. Differences analysis shows that the solid element is better than beam element in calculation. The influence of solid elements grid size on the result accuracy was conducted, and used to amend the calculation result of the solid element, which provides a certain reference on choosing the right element in the similar projects or structure simulation.

scholarly journals Experimental and Numerical Investigation on the Effects of Foundation Pit Excavation on Adjacent Tunnels in Soft Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zi-Tian Yu ◽  
Heng-Yu Wang ◽  
Wenjun Wang ◽  
Dao-Sheng Ling ◽  
Xue-Dong Zhang ◽  
...  
Keyword(s):  
Retaining Wall ◽  
Soft Soil ◽  
Shear Bands ◽  
Earth Pressure ◽  
Bending Moment ◽  
Surface Settlement ◽  
Diaphragm Wall ◽  
Foundation Pit ◽  
Obvious Effect ◽  
Diaphragm Walls

Excavations near an existing tunnel are often encountered in underground construction. The influence of the excavation on the adjacent tunnels is not yet fully understood. This study presented a centrifugal model test about excavation next to existing tunnels in soft soil foundation. The bending moment of diaphragm wall, surface settlement, tunnel deformation, and earth pressure around the tunnel were mainly studied. The influence of tunnel location is further studied by numerical simulation. During the stabilization stage of foundation pit, the diaphragm walls present convex deformation towards foundation pit, and the surface settlement outside the diaphragm wall appears to be the concave groove type. During the overexcavation stage, the diaphragm walls are almost damaged, and the shear bands are nearly tangent to the tunnels. The displacement of the tunnels and the surface settlement rapidly increase. The deformation of the diaphragm wall and the surface settlement are limited by the existing tunnel. The numerical results indicate that the change of tunnel location has little effect on the retaining wall but an obvious effect on the tunnel itself.

Calibration of a simplified method for fire resistance assessment of partially encased composite beams

2016 ◽  
Vol 7 (3) ◽  
pp. 262-282 ◽  
Author(s):  
Iolanda Del Prete ◽  
Giuseppe Cefarelli ◽  
Emidio Nigro
Keyword(s):  
Comparative Analysis ◽  
Bending Moment ◽  
Composite Beams ◽  
Calculation Model ◽  
Simplified Models ◽  
Content Type ◽  
The Moment ◽  
Simplified Calculation ◽  
Experimental Comparisons ◽  
Calculation Models

Purpose This paper aims to deal with the evaluation of the bending moment resistance of partially encased composite beams, heated from below by the standard-time temperature curve (ISO 834). Design/methodology/approach EN 1994-1-2 provides two calculation models for evaluating the sagging and hogging moment resistance: the “general simplified rules” and the “simplified models” proposed in the Annex F. Findings In this paper, these simplified calculation models were implemented on several partially encased composite beams, by means of a parametric analysis. Then, the results were compared to those obtained through an advanced calculation model, such as the Moment–Curvature model, by means of a comparative analysis. Originality/value The aim of the “parametric-comparative” analysis is the evaluation of the reliability of the Annex F simplified models. This analysis was conducted by means of both numerical-numerical and numerical-experimental comparisons. This paper provides an alternative simplified calculation model, which is easy to implement and very reliable.

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