scholarly journals Mechanical Behavior of Supporting Structure of Rectangular Deep Ventilation Shaft in Rail Transit

2019 ◽  
Vol 136 ◽  
pp. 02021
Author(s):  
Jinke Gu ◽  
Lin Huang ◽  
Feng Qiu ◽  
Xiaoguang Jin
Keyword(s):  
Mechanical Behavior ◽  
Axial Force ◽  
Three Dimensional ◽  
Bending Moment ◽  
Internal Force ◽  
Surrounding Rock ◽  
Rail Transit ◽  
Support Design ◽  
Supporting Structure ◽  
Ventilation Shaft

In order to analyze the mechanical behavior of surrounding rock and initial support during shaft excavation and support process, reveal the law of stratum displacement, the stress characteristics of surrounding rock and the internal force of supporting structure during construction, this paper establishes a three-dimensional finite element numerical model relying on the construction process of a ventilation shaft in Chongqing Rail Transit. The results show that the stress of shotcrete, the bending moment of supporting structure, the axial force of bolt and the axial force of I-beam are all within the allowable range. The "S" shape bending occurs in the range of 60m~70m for the axial force of bolt and cross brace I-beam. According to the results of model test, there is inflection point in the pressure distribution of rectangular deep ventilation shaft in rail transit, which provides a basis for the support design of deep ventilation shaft.

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.

The Bench Method Numerical Simulation of Soft Rock Tunnel

2013 ◽  
Vol 438-439 ◽  
pp. 949-953
Author(s):  
Hao Bo Fan ◽  
Jin Xing Lai ◽  
Dan Dan Hou
Keyword(s):  
Numerical Simulation ◽  
Measurement Data ◽  
Soft Rock ◽  
Simulation Method ◽  
Internal Force ◽  
Surrounding Rock ◽  
Supporting Structure ◽  
Highway Tunnel ◽  
Tunnel Design ◽  
Rock Tunnel

This paper based on Chaoyang tunnel by bench method excavation, using the finite element numerical simulation method, simulates the surrounding rock displacement of soft rock tunnel and the stress characteristics of supporting structure to get the various stages of tunnel surrounding rock stress, strain and the internal force changes of tunnel supporting structure. After the analyses of the numerical simulation results and field monitoring measurement data, the safety and rationality of the method are determined. The research provides certain reference for highway tunnel design and construction.

Geo-Stress Measurement and its Application in the Yangchangwan Coal Mine

2013 ◽  
Vol 353-356 ◽  
pp. 398-402
Author(s):  
Xiao Yu Zhang ◽  
Feng Ming Liu ◽  
Gang Chen
Keyword(s):  
Stability Analysis ◽  
Coal Mine ◽  
Basic Parameter ◽  
Stress Measurement ◽  
Three Dimensional ◽  
Stress Relief ◽  
Tectonic Stress ◽  
Surrounding Rock ◽  
Support Design ◽  
Rock Stability

The initial stress of rock is a basic parameter, which can be used for surrounding rock stability analysis, exploitation and support design. By utilizing stress relief method of hollow inclusion with its characters of high precision and obtaining three dimensional stress at one time, we have measured three dimensional stress magnitude and direction in north wing roadway (-850m) and 710 open-off cut (-1000m), respectively. The results show that the horizontal tectonic stress is obvious in this coal area.

Composite Lining Aseismic Design for Fault-Crossing Tunnel Structures

2014 ◽  
Vol 971-973 ◽  
pp. 30-34
Author(s):  
Chun Lei Xin ◽  
Bo Gao
Keyword(s):  
Active Faults ◽  
Three Dimensional ◽  
Bending Moment ◽  
Simulation Method ◽  
Internal Force ◽  
Great Earthquake ◽  
Underground Structures ◽  
Lining Structure ◽  
Internal Forces ◽  
Composite Lining

Although underground structures have stronger aseismic performance than ground structures, seismic disasters of mountain tunnels were fairly conspicuous in Wenchuan Great Earthquake. On the basis of seismic disaster analysis, a composite lining designfor tunnel structures across active fault was put forward. Three-dimensional numerical simulation method was used to analyze aseismic and damping effect of this structure. The results show that: (1)After setting aseismic and damping structure, the maximum internal forces value in lining the pattern of internal forces will not change. (2)Aseismic and damping structure setting can directly reduce the bending moment value and increase the axial force and stress force value in lining structure. (3) Relative to aseismic and damping structure, grouting region around damping layer can ameliorate internal force condition in lining structure and improve the effect of aseismic and damping structure. The above research results contribute to provide reference for seismic fortification of tunnel structures across active faults.

Influence of Side-Pressure Coefficient on Deformation of Tunnel Surrounding Rock and Bolt Axial Force

2015 ◽  
Vol 741 ◽  
pp. 138-142 ◽  
Author(s):  
Feng Hai Ma ◽  
Yan Wang ◽  
Zhi Bin Wang
Keyword(s):  
Axial Force ◽  
Lateral Pressure ◽  
Pressure Coefficient ◽  
Side Wall ◽  
Horizontal Displacement ◽  
Internal Force ◽  
Surrounding Rock ◽  
Lateral Pressure Coefficient ◽  
Finite Element Software ◽  
Side Pressure

Internal force and deformation of surrounding rock and supporting structure of the nonlinear research is the use of finite element software ADINA by ideal elastic-plastic constitutive model.Results show that the lateral pressure coefficient increased from 0 to 1, and even decrease sharply arch sedimentation of surrounding rock, side wall horizontal displacement towards the hole along the radial direction development gradually reduced to 0 and reverse to the hole, when the lateral pressure coefficient is less than 0.5, bolt axial force biggest change is not obvious, when lambda increases gradually, the largest bolt axial force significantly increased.

Mechanical Behavior of Segmented Lining Structure of Tunnel under Acting Ground Fractures in Xi’an Zone

2011 ◽  
Vol 261-263 ◽  
pp. 1778-1783
Author(s):  
Sheng Jun Shao ◽  
Fang Tao She ◽  
Juan Fang
Keyword(s):  
Tensile Stress ◽  
Mechanical Behavior ◽  
Compressive Stress ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Maximum Tensile Stress ◽  
Internal Force ◽  
Subway Tunnel ◽  
Lining Structure ◽  
Pass Through

Xi’an ground fracture, caused by the extraction of groundwater and the movement of fault under soil strata, is a geo-hazard. The movement of ground fracture originates the uneven settlement of upward block and downward block. In Xi’an ground fracture region, the segmented lining structure was adopted in subway tunnel to pass through the ground fracture, so as to adapt for the uneven settlement. Three-dimensional elastic-plastic finite difference method was applied to simulate the initial lining structure, second segmented lining structure, surrounding soils and ground fracture. The horizontal and vertical displacement of segmented lining structure, surrounding soils pressure and internal force of segmented lining structure in subway tunnel were analyzed by the calculation results. The knowledge on mechanical behavior of segmented lining structure passing through an active ground fracture and surrounding soils was shown as following. The relative vertical displacement between segmented lining structure sects beside the ground fracture increases remarkably with the movement of ground fracture, and the segmented lining structure located in upward displaceent block near ground fracture originates notable rotary. Tension or compression deformation occured in the deformation joint between adjacent segmented lining structures near the ground fracture.There was a significant change in the contact pressure of the first sect of lining structure in the upward displace block. Under the same uniform settlement at the bottom of upward diaplacement block, the relativly vertical displacemtn on the surfaceof ground fracture strata without tunnel equals 50cm, but the relativly vertical displacement between adjacent segmented lining structure at ground fracture is 18.2cm on the design level of arch top of lining strcutre. the maximum tensile stress of segmented lining structure is 2.02MPa, the maximum compressive stress of segmented lining is 3.49MPa. In conclusion, segmented lining structure can adapts to the uneven settlement caused by the movement of ground fracture. Though maximum tensile and compressive stress of sengmented lining structure passing through the active ground fracture is bigger than the general lining structure located in soils strata without the ground fracture, the segmented lining structure constructed by the steel fibre concrete can bear with the maximum tensile stress.

scholarly journals Numerical analysis of symmetrical and asymmetrical reinforced concrete flat slabs - an integrated slab/ column analysis

2016 ◽  
Vol 9 (3) ◽  
pp. 306-356
Author(s):  
A. Puel ◽  
D. D. Loriggio
Keyword(s):  
Numerical Analysis ◽  
Axial Force ◽  
Three Dimensional ◽  
Bending Moment ◽  
Bending Moments ◽  
Flat Slabs ◽  
Distributed Load ◽  
Significant Difference ◽  
Local Support ◽  
Internal Forces

ABSTRACT This paper studies the modeling of symmetric and asymmetric flat slabs, presenting alternatives to the problem of singularity encountered when the slab is modeled considering columns as local support. A model that includes the integrated slab x column analysis was proposed, distributing the column reactions under the slab. The procedure used transforms the bending moment and column axial force in a distributed load, which will be applied to the slab in the opposite direction of gravitational loads. Thus, the bending moment diagram gets smooth in the punching region with a considerable reduction of values, being very little sensible to the variation of used mesh. About the column, it was not seen any significant difference in the axial force, although the same haven't occurred with the bending moments results. The final part of the work uses geoprocessing programs for a three-dimensional view of bending moments, allowing a new comprehension the behavior of these internal forces in the entire slab.

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 Internal Force Analysis of Parabolic Arch Considering Shear Effect under Gradient Temperature

2021 ◽  
Vol 631 (1) ◽  
pp. 012053
Author(s):  
Fulin Shen ◽  
Xiaochun Song
Keyword(s):  
Temperature Gradient ◽  
Axial Force ◽  
Slenderness Ratio ◽  
Bending Moment ◽  
Internal Force ◽  
Gradient Field ◽  
Parameter Study ◽  
Linear Temperature ◽  
Linear Temperature Gradient ◽  
Parabolic Arch

Abstract This paper theoretical analysis the internal force of the fixed parabolic arches under radient temperature gradient field incorporating shear deformations. The effective centroid of the arch-section under linear temperature gradient is derived. Based on force method and energy method, the analytical solutions of the internal force of fixed parabolic arches at pre-buckling under linear temperature gradient field are derived. A parameter study was carried out to study the influence of linear temperature gradient on the internal force of the fixed parabolic arches with different rise-span ratio and varying slenderness ratio. It is found that the temperature gradient and the rise-span ratio has a significant influence on the internal force of the parabolic arches, the influence of shear deformation causes the bending moment increase while the axial force decreases, and the axial force of parabolic arches decreases as the rise-span ratio increases.

scholarly journals Comparative study on bearing mechanism and design parameters of confined concrete arch joints in deep soft rock roadway

2019 ◽  
Vol 6 (4) ◽  
pp. 493-504
Author(s):  
Wei Lu ◽  
Qi Wang ◽  
Bei Jiang ◽  
Shuo Xu ◽  
Bohong Liu ◽  
...  
Keyword(s):  
Failure Modes ◽  
Soft Rock ◽  
Bending Moment ◽  
High Strength ◽  
Internal Force ◽  
Confined Concrete ◽  
Design Parameters ◽  
Support Design ◽  
Soft Rock Roadway ◽  
Rock Roadway

Abstract Square confined concrete arch is increasingly used in deep soft rock roadway support because of its advantages of high strength and construction convenience. However, the design of confined concrete arch in underground engineering still remains in experience-based method and lacks quantitative analysis. As a connecting component between arch sections, the connection joints have an important influence on the internal force distribution and failure mechanism of support arch. Therefore, a reasonable design of arch joints is the premise of rational support design. Taking Liangjia Coal Mine, a typical deep soft rock mine in China, as research background, this paper fully compared the most widely used joint types of confined concrete arch as analytical objects: flange joints and casing joints. The main failure modes of these two kinds of joints under bending moment are defined. Laboratory and numerical tests are carried out to study the mechanical characteristics of joints. Based on the M–θ curve, the influence law of different design parameters is analyzed, and the design principles of joints are proposed. The research results could provide a theoretical basis for the design and application of confined concrete arch in related projects.

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