scholarly journals Experimental Investigation on the Influence of Regional Concrete Spalling on Shield Tunnel Segments

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Shimin Wang ◽  
Chuankun Liu ◽  
Gaoyu Ma ◽  
Songyu Cao ◽  
Junbo Zhang ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Reduction Rate ◽  
Internal Force ◽  
Field Investigation ◽  
Ultimate Bearing Capacity ◽  
Shield Tunnel ◽  
Damage And Failure ◽  
Lining Structure ◽  
Critical Instability

Based on the field investigation and analysis, the mechanical characteristics of segment structure in shield tunnels are compared and analyzed under the circumstances of different concrete spalling region by the method of similarity model experiment. Through data analysis of acoustic emission, the results for displacement and internal force of shield tunnel segments are clarified on the segment lining, the influential rule of load bearing capacity is also determined, and the deformation and stress for the different concrete spalling region are described as well. The corresponding research results indicate that range for elastic bearing stage is enlarged while it is narrowed for plastic bearing stage, the convergence and deformation and the accumulated event numbers for acoustic emission on critical instability point are obviously increasing, and the process of damage and failure tends to be sudden for segment lining structure. The ultimate bearing capacity of the damaged segment lining obviously decreases due to regional concrete spalling; to be more specific, the reduction rate for ultimate bearing capacity becomes 6%, 6%, and 13%, respectively, when the range of concrete spalling reaches 45°, 60°, and 75°.

scholarly journals Study on the Formation Mechanism of Rock Burst Caused by Seam Floor Slip under an Ultrathick Conglomerate

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhiyong Ma ◽  
Wenkai Feng ◽  
Zhen Wang ◽  
Fujin Lin ◽  
Dayong Li
Keyword(s):  
Bearing Capacity ◽  
Rock Burst ◽  
Abutment Pressure ◽  
Microseismic Monitoring ◽  
Field Investigation ◽  
Ultimate Bearing Capacity ◽  
Estimation Model ◽  
Rock Bursts ◽  
High Level ◽  
And Control

A rock burst accident occurred on coalface 13230 of the Gengcun Coal Mine in Henan Province. Through a field investigation, theoretical analysis, and microseismic monitoring, we studied how the rock burst, which was caused by overall seam floor slip and instability, occurring under an ultrathick conglomerate. Because the overlying ultrathick conglomerate in the mined-out zone close to coalface 13230 had been inadequately mined, the leading section of the coalface was under a high level of stress. Combined with the tectonic stresses from the F16 faultage and the soft floor structure, these factors caused the floor of this coalface to trigger the overall slip-type rock burst. In this paper, an estimation model of the ultimate bearing capacity of a seam floor under an ultrathick conglomerate and the advancing abutment pressure on the coalface is presented. This model is used to show that the ultimate bearing capacity of the seam floor on coalface 13230 is 26.3 MPa, and the abutment pressure is far more than the floor bearing capacity. We also present pressure relief and reinforced supporting measures, which can effectively prevent floor slip-type rock bursts from occurring. The results of this study provide a reference for the prevention and control of floor slip-type rock bursts in coal mining under an ultrathick conglomerate.

Elastic Modulus Reduction Method Based Limit Analysis of Steel Lined Reinforced Concrete Penstocks Containing Flaws

2013 ◽  
Vol 671-674 ◽  
pp. 879-883
Author(s):  
Shu Lin Liu ◽  
Chuan Xiong Fu ◽  
Wei Zhang
Keyword(s):  
Elastic Modulus ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Reduction Method ◽  
Internal Force ◽  
Ultimate Bearing Capacity ◽  
Curve Beam ◽  
Beam Model ◽  
Force Calculation ◽  
Modulus Reduction

In the context of ultimate bearing capacity of steel lined reinforced concrete penstock (SLRCP) containing flaws, the use of the elastic modulus reduction method (EMRM) in conjunction with curve beam based internal force calculation is presented. The corrosion models for steel bar and lining are introduced from the literature. The SLRCP is considered bearing load together with lining and reinforced concrete, and its internal force is determined based on a simplified curve beam model. The element bearing ratio of SLRCP is given through the internal force and sectional strength, and is employed by the EMRM. The change of ultimate bearing capacity of some typical SLRCP within their operating life is then evaluated.

The Finite Element Simulation Analysis of Urban Subway Shield Tunnel

2014 ◽  
Vol 711 ◽  
pp. 514-519
Author(s):  
Feng Qi Zhu ◽  
Huan Qin Liu ◽  
Jian Zhang
Keyword(s):  
Finite Element ◽  
Simulation Analysis ◽  
Three Dimensional ◽  
Internal Force ◽  
Ground Subsidence ◽  
Shield Tunnel ◽  
Tunnel Construction ◽  
Subway Tunnel ◽  
Underground Engineering ◽  
Lining Structure

Shield tunning method has been used widely in urban underground engineering. Based on a certain range of Wuhan subway shield tunnel, the subway shield tunnel segment of the internal force and deformation were studied by the load structure method and stratum structure method. Influence of the formation parameters and the parameters of the lining structure on the segment internal force and deformation was analyzed. And the tunnel construction was modeled by three-dimensional dynamic finite element method. The influence of the construction process about ground subsidence and segment stress was discussed, in order to guide urban subway tunnel construction design.

Experiment and Theory Study on Ultimate Bearing Capacity of Reinforced Concrete Tubular Hollow Continuous Slab

2012 ◽  
Vol 204-208 ◽  
pp. 782-785
Author(s):  
Zhen Hao Zhang ◽  
Wei Jun Yang ◽  
Zhi Gang He
Keyword(s):  
Bearing Capacity ◽  
Ultimate Load ◽  
Complete Solution ◽  
Hollow Structure ◽  
High Strength ◽  
Internal Force ◽  
Ultimate Bearing Capacity ◽  
Thin Wall ◽  
Continuous Slab ◽  
Plastic Limit Analysis

The tubular hollow slab inside which GBF high-strength thin-wall pipes are placed is a new type of hollow structure. First the ultimate bearing capacity of tubular hollow continuous slab is measured by experiment. Then the ultimate bearing capacity of the tubular hollow continuous slab is studied by plastic limit analysis method. And the complete solution of structural ultimate load under condition of full internal force redistribution is solved. The study show that the measured values of ultimate load are all a little larger than the theoretical values of ultimate load, which shows that the tubular hollow slab develop full internal force redistribution. So it can be concluded that the tubular hollow slab has fine performance of plastic internal force redistribution.

scholarly journals Study on the ultimate bearing capacity of a strip footing influenced by an irregular underlying cavity in karst areas

2021 ◽  
Author(s):  
Lianheng Zhao ◽  
Shan Huang ◽  
Zhonglin Zeng ◽  
Rui Zhang ◽  
Gaopeng Tang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Strip Footing ◽  
Karst Areas

Experimental Investigation for Horizontal Ultimate Bearing Capacity and Target Ductility Factor Improvement Results of the RC Column Reinforced by AFL with Damages

2014 ◽  
Vol 488-489 ◽  
pp. 497-500
Author(s):  
You Lin Zou ◽  
Pei Yan Huang
Keyword(s):  
Bearing Capacity ◽  
Ultimate Bearing Capacity ◽  
Test Results ◽  
Rc Columns ◽  
Static Test ◽  
Rc Column ◽  
Ductility Factor ◽  
Secant Stiffness ◽  
Function Relationship ◽  
Reversed Cyclic

Deem test results from the low reversed cyclic loading quasi-static test with 2 RC columns as the basic information of secant stiffness damage of the reference column and take use of the TMS instrument in the test to artificially make the damage percentage of secant stiffness of the RC column as 33%, 50% and 66%, 6 damaged columns in total; reinforce the 6 damaged columns and 2 undamaged ones under the same conditions with AFL, through quasi-static contrast test. Test results show that it is able to effectively boost horizontal ultimate bearing capacity and ductility deformability of the RC columns with AFL for reinforcement; besides, there is a linear function relationship between horizontal ultimate bearing capacity, target ductility factor, and damage percentage of secant stiffness.

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