Influence of Symmetric and Asymmetric Voids on Mechanical Behaviors of Tunnel Linings: Model Tests and Numerical Simulations

The presence of symmetric and asymmetric voids directly affects the mechanical behaviors of tunnel linings and further induces tunnel diseases among influence factors. In this paper, 1:5-scale model tests were carried out to study the mechanical behaviors of reinforced concrete (RC) linings considering the voids located at the crown and at the spandrel. Based on the experimental results and concrete plastic damage (CDP) model, the effects of void (i.e., location and size), subgrade stiffness, and lining size on bearing capacity of RC lining were investigated using numerical simulation. The results of model test and parametric analysis showed that the existence of voids significantly affected the mechanical behavior of the lining during inelastic deformation period. The lining with a larger void size corresponded to low bearing capacity and larger deformation around the void, thus increasing the damage possibility of linings. The influence of voids on the bearing capacity of linings varied with the void location, load direction (especially under horizontal symmetrical loads), and subgrade stiffness. High soil stiffness corresponded to a great influence of the void size on the lining bearing capacity. In addition, the lining strength increased inconsistently with the increase of model size. On the basis of parameter sensitivity analysis, the Levenberg–Marquardt (L-M) optimization algorithm and Logistic model were used to establish the equation of lining bearing capacity loss rate considering the void effect.

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Numerical Simulation on the Regular Pattern of the Lateral Friction Transmission of the Pile in the Incline under the Pulling Force

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.501-504.248 ◽

2014 ◽

Vol 501-504 ◽

pp. 248-253

Author(s):

Liu Yong Cheng ◽

Shan Xiong Chen ◽

Xi Chang Xu ◽

Xiao Jie Chu ◽

Tong Bing Lei

Keyword(s):

Numerical Simulation ◽

Bearing Capacity ◽

Pile Foundation ◽

Influence Factors ◽

Great Influence ◽

Regular Pattern ◽

Slope Gradient ◽

Pulling Force ◽

Lateral Friction

The regular pattern of the lateral friction transmission is one of the most critical influences on the ultimate uplift bearing capacity. The pile foundation in the incline under the pulling force has a wide variety of characteristics which is different with the normal pile. Numerical simulation is done by the use of FLAC3D in this paper. The regular pattern of the lateral friction transmission of the pile in the incline under the pulling force is studied. And the influence factors on the lateral friction transmission such as the slope gradient, the length and location of piles are discussed. The results show that the incline has a great influence on the lateral friction transmission. The lateral friction which is away from the incline-side is about 30% to 50% bigger than the incline-side. The slope gradient and the location of piles all have a great influence on the lateral friction transmission.

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Bearing Capacity Analysis on Slotted End Plate Connection Joints of Different Types

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.166-169.764 ◽

2012 ◽

Vol 166-169 ◽

pp. 764-769

Author(s):

Ruo Hui Qiang ◽

Ming Zhou Su ◽

Junfen Yang ◽

Jinbo Cui

Keyword(s):

Bearing Capacity ◽

Failure Modes ◽

Great Influence ◽

Mechanical Behaviors ◽

End Plate ◽

Different Types ◽

Plastic Stage ◽

Plate Connection ◽

Force Displacement ◽

Main Factor

Four different types of full-scale slotted end plate (SEP) connection joints are tested to determine their failure modes and damage mechanisms under ultimate loading. Researches on mechanical behaviors of I-type, T-type, U-type and Groove SEP connection joints bearing compression are studied, which also analyze their force-displacement behaviors and developing processes of deformation and strain. The results show that the bearing capacities of I, grooved, T and U types SEP connections are increased gradually, which indicate the SEP’s type has great influence on the ultimate strength of joints. The instability of SEP is the main factor to cause the loss of bearing capacity of the connection, which is shown through the development of strain, that SEP enters into plastic stage and the other regions still are elastic.

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Pile Model Tests Using Strain Gauge Technology

Studia Geotechnica et Mechanica ◽

10.1515/sgem-2015-0032 ◽

2015 ◽

Vol 37 (3) ◽

pp. 49-52 ◽

Cited By ~ 1

Author(s):

Adam Krasiński ◽

Tomasz Kusio

Keyword(s):

Bearing Capacity ◽

Axial Force ◽

Strain Gauge ◽

Force Measurement ◽

Ground Level ◽

Model Tests ◽

Scale Model ◽

Small Scale ◽

Pile Head ◽

Pile Model

Abstract Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

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Design and Performance of Concrete Pile Strengthened with Lengthened Steel-Tube Core: Model Tests and Numerical Simulations

Mathematical Problems in Engineering ◽

10.1155/2021/5592296 ◽

2021 ◽

Vol 2021 ◽

pp. 1-18

Author(s):

Shangyu Han ◽

Lei Yun

Keyword(s):

Bearing Capacity ◽

Axial Force ◽

Mechanical Performance ◽

Load Capacity ◽

Steel Tube ◽

Model Tests ◽

Scale Model ◽

Conventional Concrete ◽

Concrete Piles ◽

Concrete Pile

In order to solve the problem of insufficient bearing capacity of existing concrete piles, a type of concrete pile with an additional lengthened strengthening core is designed, by inserting the steel tube through guiding hole and pouring core concrete. To reveal the mechanical performance of the reinforced piles, scale model tests and finite element simulations were performed. The results showed that both the vertical and horizontal bearing capacity increase with the length of the stiffening core. The axial force of the enhanced core is also smaller than conventional concrete piles, and the extended core can share the axial force of the foundation pile to improve the stress distribution of the pile body. These findings point toward a useful and general method for increasing the load capacity of existing concrete piles.

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EXTREME WAVE PRESSURES AND LOADS ON A PILE-SUPPORTED WHARF DECK - INFLUENCES OF AIR GAP AND WAVE DIRECTION

Coastal Engineering Proceedings ◽

10.9753/icce.v36.waves.5 ◽

2018 ◽

pp. 5

Author(s):

Andrew Cornett

Keyword(s):

Offshore Structures ◽

Model Tests ◽

Scale Model ◽

Extreme Waves ◽

Wave Direction ◽

Coastal Structures ◽

Extreme Wave ◽

Wave Impact ◽

The Past ◽

Water Depths

Many deck-on-pile structures are located in shallow water depths at elevations low enough to be inundated by large waves during intense storms or tsunami. Many researchers have studied wave-in-deck loads over the past decade using a variety of theoretical, experimental, and numerical methods. Wave-in-deck loads on various pile supported coastal structures such as jetties, piers, wharves and bridges have been studied by Tirindelli et al. (2003), Cuomo et al. (2007, 2009), Murali et al. (2009), and Meng et al. (2010). All these authors analyzed data from scale model tests to investigate the pressures and loads on beam and deck elements subject to wave impact under various conditions. Wavein- deck loads on fixed offshore structures have been studied by Murray et al. (1997), Finnigan et al. (1997), Bea et al. (1999, 2001), Baarholm et al. (2004, 2009), and Raaij et al. (2007). These authors have studied both simplified and realistic deck structures using a mixture of theoretical analysis and model tests. Other researchers, including Kendon et al. (2010), Schellin et al. (2009), Lande et al. (2011) and Wemmenhove et al. (2011) have demonstrated that various CFD methods can be used to simulate the interaction of extreme waves with both simple and more realistic deck structures, and predict wave-in-deck pressures and loads.

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Large scale model tests on Royal Schelde SES

10.2514/6.1989-1441 ◽

1989 ◽

Author(s):

R. DE GAAIJ ◽

E. VAN RIETBERGEN ◽

M. SLEGERS

Keyword(s):

Large Scale ◽

Model Tests ◽

Scale Model ◽

Large Scale Model

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Analysis of Electromagnetic Inverse Model of Resistance Spot Welding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.160-162.974 ◽

2010 ◽

Vol 160-162 ◽

pp. 974-979

Author(s):

Nai Feng Fan ◽

Zhen Luo ◽

Yang Li ◽

Wen Bo Xuan

Keyword(s):

Resistance Spot Welding ◽

Regularization Method ◽

Spot Welding ◽

Influence Factors ◽

Great Influence ◽

Welding Process ◽

Inverse Model ◽

Resistance Spot ◽

Inversion Theory

Resistance spot welding (RSW) is an important welding process in modern industrial production, and the quality of welding nugget determines the strength of products to a large extent. Limited by the level of RSW quality monitor, however, RSW has rarely been applied to the fields with high welding quality requirements. Associated with the inversion theory, in this paper, an electromagnetic inverse model of RSW was established, and the analysis of influence factors, such as the layout of the probes, the discrete program and the regularization method, was implemented as well. The result shows that the layout of the probe and the regularization method has great influence on the model. When the probe is located at the y direction of x-axis or the x direction of y-axis and Conjugate Gradient method is selected, a much better outcome can be achieved.

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