scholarly journals Study on Time-Space effect and earth berm of foundation pit

2021 ◽  
Vol 787 (1) ◽  
pp. 012122
Author(s):  
Wang Ruifang ◽  
Luolan ◽  
Pi Juhua
Keyword(s):  
Foundation Pit ◽  
Time Space ◽  
Space Effect

Research on Deformation Mechanism of Surrounding Rock during Excavation of Large-Span Shallow-Buried Double-Arch Tunnel

2013 ◽  
Vol 392 ◽  
pp. 890-894
Author(s):  
Shao Rui Sun ◽  
Ye Xu Lu ◽  
Shao Hua Zhang ◽  
Ji Min Wu
Keyword(s):  
Deformation Mechanism ◽  
Back Analysis ◽  
Ground Surface ◽  
Surrounding Rock ◽  
Tunnel Excavation ◽  
Large Span ◽  
Main Work ◽  
Time Space ◽  
Space Effect ◽  
Force Mechanism

The deformation mechanism of surrounding rock during excavation is difficult to stability evaluation for large-span shallow-buried double-arch tunnel. Take Fenghuang mountain tunnel in Suzhou city as an example, the main work and funding are as follow: The measured data in the middle of the tunnel, including settlement on the top of the tunnel and deformation between two lateral walls, were used to calculate mechanical parameters by back analysis method. The obtained parameters were used to calculate the deformation and stress of the main tunnel excavation in the different steps. The rules includes time-space effect during main tunnel excavation, force mechanism of the middle wall and settlement on the ground surface for the surrounding rock in the main tunnel. Finally, the calculated settlement and deformation were compared to the monitoring results. The safety coefficient of surrounding rock for double-arch tunnel was obtained by strength reduction theory.

Analysis of the Effects on Optimization Design about Double-Row Piles Retaining Structure

2012 ◽  
Vol 204-208 ◽  
pp. 72-78
Author(s):  
Yu Wang ◽  
Yan Ting Yang ◽  
Feng Yu ◽  
Guang Lei Hu
Keyword(s):  
Optimization Design ◽  
Internal Force ◽  
Composite Foundation ◽  
Foundation Pit ◽  
Double Row ◽  
Retaining Structure ◽  
Supporting Structure ◽  
Arch Effect ◽  
Space Effect ◽  
Foundation Pile

Double-row piles retaining structure has been widely used in the project now, but the stress mechanism of double-row pile is more complex; Its internal force and deformation are affected by many factors. Understanding and mastering its effects has an important significance for the design and the optimization of double-row pile supporting structure. According to the comparison of the measured data and theoretical calculation about original support scheme and optimized support plan and combined with the soil test data, this paper takes the Jinan Cultural Arts Center(Theatre) stage bin foundation pit as an example to analyse the main effects of optimization design about double-pile supporting structure. The results show that soil shear strength, soil arch effect, influence of CFG composite foundation, pile-beam synergy effect and space effect of foundation pit play an important role for optimization design about double-pile supporting structure.

Analytical Solution of Stress and Displacement Fields of Frozen Wall in Deep Alluvium According for Time-Space Effect

2012 ◽  
Vol 170-173 ◽  
pp. 1820-1826
Author(s):  
Mao Yan Ma ◽  
Hua Cheng ◽  
Chuan Xin Rong
Keyword(s):  
Analytical Solution ◽  
Radial Stress ◽  
Displacement Fields ◽  
Time Space ◽  
Stress And Displacement Fields ◽  
Calculation Results ◽  
Space Effect ◽  
Frozen Wall ◽  
Theory Of Viscoelasticity ◽  
Shaft Wall

Based on the theory of viscoelasticity and the principle of interaction between surrounding rock and structure in unload state, analytical solution of the stress field and displacement field of the frozen wall is obtained. Calculation results of the stress and displacement fields suggest that radial stress and displacement in the sidewall are very large within 15 days after pouring concrete of the outer shaft wall, which is proved by the fact that engineering incidents such as shaft wall rupture happen exactly at this time. The results also indicate that radial stress at different points in frozen wall all tend to the imposed loads on outer frozen wall finally, and that means the frozen wall is fluidized. This calculation theory can be used in the design of frozen wall in deep alluvium.

scholarly journals Structural Dynamic Response of a Shield Tunnel under Aircraft Taxiing Load

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhanyou Luo ◽  
Kuangqin Xie ◽  
Baoping Zou ◽  
Mingyao Jiang ◽  
Wei Zheng
Keyword(s):  
Dynamic Response ◽  
Three Dimensional ◽  
Shield Tunnel ◽  
Transverse Displacement ◽  
Tunnel Structure ◽  
Subway Tunnel ◽  
Structural Dynamic ◽  
Sliding Speed ◽  
Time Space ◽  
Space Effect

Dynamic load is an important factor affecting the safety and stability of subway tunnel structures. To obtain the variation law of shield tunnel structure dynamic response under aircraft taxiing load, a three-dimensional numerical simulation of such tunnel under the action of aircraft taxiing load is performed on the basis of a project involving a shield tunnel orthogonal underpass taxiway. The effects of sliding speed and tunnel depth on the structure of the shield tunnel are also analyzed. The results show that the transverse displacement and acceleration response of tunnel segment exhibit evident time-space effect under the action of aircraft taxiing load. The transverse displacement and arch waist acceleration of the shield segment increase first and then decrease. The transverse displacement of the arch waist reaches its maximum when the aircraft taxis directly above the tunnel. The sliding speed exhibits an evident influence on the dynamic response of shield tunnel structure. The vertical and convergence displacements of tunnel segments increase with the increase in sliding speed. The dynamic response of tunnel structure is significantly affected by the factors of tunnel buried depth. The vertical and convergence displacements of tunnel segments decrease with the increase in tunnel buried depth. Therefore, the safety of the shield tunnel structure can be ensured by controlling the taxiing speed when the aircraft taxis directly above the tunnel. The measures of increasing the buried depth of the tunnel or strengthening the tunnel structure need to be considered when the taxiing speed is large.

An Approximate Prediction of Metro Pit’s Sub-Step Excavation

2011 ◽  
Vol 90-93 ◽  
pp. 1926-1930
Author(s):  
Wen Wang ◽  
Hong Shan Liu
Keyword(s):  
Exposure Time ◽  
Prediction Method ◽  
Effective Modulus ◽  
Time And Space ◽  
Time Space ◽  
Space Effect

To combine the characters of metro pits and time-space effect, an approximate prediction method is studied. Sub-step excavation width, depth, unsupported exposure time and space effect are the main reasons for the displacement of excavation. To calculate the comparative displacement ratios of different parameters variational conditions and standard excavation condition, the displacement effective modulus of every parameter are obtained, and the differences of every layer excavation are also considered. The displacement of excavation can be predicted when the excavation parameters changed based on this method, and the displacement can be controlled by modulating the excavation parameters.

Simulating and Testing Study on Construction Temporal-Spatial Effect of Six Lanes Multi-Arch Tunnel

2012 ◽  
Vol 446-449 ◽  
pp. 2149-2155 ◽  
Author(s):  
Xiao Guang Jin ◽  
Bing Wei Cui ◽  
Meng Jun Wu
Keyword(s):  
Simulation Method ◽  
Wall Rock ◽  
Spatial Effect ◽  
Surrounding Rock ◽  
Construction Process ◽  
Similar Model ◽  
Time Space ◽  
Space Effect ◽  
Finite Element Numerical Simulation ◽  
Construction Practice

Abstract: Owing to several construction procedures of bidirectional 6 lane multi-arch tunnel, with the characteristics of large dig span and flat cross section, the wall rock and support structure of which will be repeatedly disturbed by multiple excavations, so their mechanical and deformational features are remarkably complicated. Combined with the design and construction practice of Sha Tangkeng bidirectional 6 lane multi-arch tunnel of Guang-He highway, taking the V grade surrounding rock for case, with the help of 3-dimension finite element numerical simulation method and 3-dimension physical similar model test, the paper studied the entire dynamic construction process of bidirectional 6 lane multi-arch tunnel, analyzed the chang characteristics of displacement and stress of wall rock and stress of supporting structure, and revealed the time-space effect laws of construction of bidirectional 6 lane multi-arch tunnel.

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