scholarly journals Performance Investigation of Tunnel Lining with Cavities around Surrounding Rocks

2020 ◽  
Vol 2020 ◽  
pp. 1-5 ◽  
Author(s):  
Jiajia Li ◽  
Yong Fang ◽  
Cheng Liu ◽  
Yongxing Zhang ◽  
Weihua Lu
Keyword(s):  
Stress State ◽  
Numerical Investigation ◽  
Tunnel Lining ◽  
Cavity Size ◽  
Cavity Depth ◽  
Tunnel Stability ◽  
Severe Effect ◽  
Single Cavity ◽  
Cavity Width

This paper presents a systematical numerical investigation into the lining performance of a tunnel with cavities around surrounding rocks, focusing on the influences of cavity size and multicavity distribution. The study demonstrates that the cavities around surrounding rocks have much influence on tunnel stability and may induce damages in tunnel structures, in which cavity width has a more severe effect on the stress state of tunnel structures than cavity depth. Moreover, the numerical investigation also illustrates that the nonadjacent distribution of multicavities has more serious influence on tunnel structures than that from adjacent distribution of multicavities as well as that from a single cavity.

scholarly journals Analysis of Structural Response of Subway Shield Tunnel Lining under the Influence of Cavities

2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Yufeng Shi ◽  
Zhaoyang Chen ◽  
Duqiang Wei ◽  
Tao Zhang ◽  
Xuming Zhou ◽  
...  
Keyword(s):  
Structural Response ◽  
Bending Moment ◽  
Tunnel Lining ◽  
Structural Safety ◽  
Shield Tunnel ◽  
Cavity Depth ◽  
Stiffness Reduction ◽  
Lining Structure ◽  
Reduction Effect ◽  
Single Cavity

The existence of cavities behind the shield tunnel lining can cause cracking, broken pieces, water leakage, and other problems, which reduces the durability and safety of the shield tunnel segment structure. In order to clarify the mechanism of cavity damage, a more systematic study of the effects of cavities on the shield tunnel lining structure from the angle, depth, and the number of cavities is carried out using model tests and numerical simulations without considering the effects of the stiffness reduction effect at the tunnel segment joints and groundwater seepage in this paper. The findings show that the bending moment value and the cavity angle value are approximately linear with the increase of single cavity angle, and the bending moment at the vault arch is reversed when the angle of the cavity behind the arch is greater than 30°. With the increase of single cavity depth, the axial force and bending moment at the cavity increase, and the distribution of bending moment remains unchanged, and the bending moment tends to be stable and unchanged beyond a certain depth. With the increase of single cavity angle and depth, the structural safety coefficient of the segment decreases, and the degree of influence is angle value > depth value. The existence of multiple cavities intensifies the influence of each cavity on the segment, especially when there are cavities behind the top and bottom of the vault; the bending moment value of the top of the vault increases by 22.53% compared with that of the single cavity condition.

Numerical Investigation of a Square Back Vehicle Equipped With a Single Cavity and Multi-Cavity

2020 ◽  
Author(s):  
Naveen Koppa Shivanna ◽  
Pritanshu Ranjan ◽  
Shibu Clement
Keyword(s):  
Drag Reduction ◽  
Numerical Investigation ◽  
Bluff Body ◽  
Body Height ◽  
The Body ◽  
Vehicle Model ◽  
Cavity Depth ◽  
Passive Flow ◽  
The Mean ◽  
Single Cavity

Abstract This work aims to investigate the comparative effect of two passive flow controls in modifying the mean wake topology around a simplified square back vehicle model. The two passive flow controls are (i) Single cavity and (ii) Multi-cavity. A straight cavity with an optimum depth at the rear base of a vehicle is a well-known technique used to alter the mean wake topology and achieve drag reduction[1]. For two dimensional bluff bodies, a multi-cavity is known to deliver better drag reduction at shorter cavity depths in comparison to a single cavity[2]. With this viewpoint, a numerical investigation is carried out to examine the performance of a multi-cavity over a single cavity in drag reduction for a three-dimensional bluff body vehicle model. The numerical simulations are performed at Reynolds Number (Re) = 1 × 105 using the k-ω SSTSAS turbulence model in a Finite volume open-source code OpenFOAM. The investigations revealed, for any cavity depth, a single cavity always performed better than multi-cavity in reducing drag. However, at optimum cavity depth equal to 33% of the body height, the drag reduction magnitude was identical for both the flow controls. The plausible mechanisms responsible for their relative difference in performance will be explored by analyzing the base pressure distribution, wake mean topology, and the temporal behavior of the wake.

Stress state analysis of two-way tunnel lining at different stages of soil defrostation

2019 ◽  
Vol 10 ◽  
pp. 160-171
Author(s):  
M.S. Pleshko ◽  
◽  
M.V. Pleshko ◽  
I.V. Voynov ◽  
A.V. Kostyukhov ◽  
...  
Keyword(s):  
Stress State ◽  
Tunnel Lining ◽  
State Analysis

2D numerical investigation of segmental tunnel lining behavior

2013 ◽  
Vol 37 ◽  
pp. 115-127 ◽  
Author(s):  
Ngoc-Anh Do ◽  
Daniel Dias ◽  
Pierpaolo Oreste ◽  
Irini Djeran-Maigre
Keyword(s):  
Numerical Investigation ◽  
Tunnel Lining

scholarly journals Numerical Investigation on the Effects of Structural Parameters of Labyrinth Cavity on Sealing Performance

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Jianmei Feng ◽  
Lingzi Wang ◽  
Hang Yang ◽  
Xueyuan Peng
Keyword(s):  
Structural Parameters ◽  
Piston Compressor ◽  
Labyrinth Seal ◽  
Dynamics Model ◽  
Cavity Depth ◽  
Sealing Performance ◽  
Leakage Characteristics ◽  
Experimental Rig ◽  
Cavity Width ◽  
Good Agreement

This paper presents a study on the leakage characteristics of a labyrinth piston compressor. A computational fluid dynamics model was applied to predict the effects of different structural parameters of the labyrinth seal on the sealing performance. The velocity field through the sealing clearance and labyrinth cavity was demonstrated and analyzed. An experimental rig was built to validate the simulation model, and the results of the simulation and experimental data showed a good agreement. The effects of the cavity width, cavity depth, tooth thickness, and clearance of the seal on the leakage characteristics were discussed in detail. The results showed that, except for the significant influence of the labyrinth clearance, d/δ (the ratio of cavity depth to labyrinth clearance) should be bigger than 2.7 to achieve the minimum leakage flow, and the effect of the varied cavity width can be ignored. Moreover, when the piston length and cavity width remain constant, the thinner the tooth thickness, the greater the number of labyrinth cavities that can be arranged, and the higher the sealing performance achieved.

Numerical investigation of the WC re-precipitation impact on the residual stress state in WC20 wt.-%Co hardmetal

2019 ◽  
Vol 84 ◽  
pp. 105003
Author(s):  
Wolfgang Kayser ◽  
Stanley van Kempen ◽  
Alexander Bezold ◽  
Mirko Boin ◽  
Robert Wimpory ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Numerical Investigation ◽  
Residual Stress State

scholarly journals Investigation of the influence of the railroad track on the stress state of the tunnel lining

2018 ◽  
Vol 239 ◽  
pp. 01020
Author(s):  
Mikhail Pleshko ◽  
Alexei Revyakin ◽  
Natalia Malishevskaya
Keyword(s):  
Stress State ◽  
Numerical Model ◽  
Stress Distribution ◽  
Elastic Layer ◽  
Tunnel Lining ◽  
Railway Track ◽  
Deformation Characteristics ◽  
Railroad Track ◽  
Circular Tunnel ◽  
Moving Vehicles

Tunnel lining takes significant loads from moving vehicles. The consequences of their impact depend on the design of the railway track and the deformation characteristics of its elements. For their study, a numerical model of a circular tunnel has been developed. As a result of the model calculation, the values of the main vertical stresses in the main tunnel structures were obtained. It is established that with increasing loads from the wheel to the rail from 100 to 200 kN, the voltage on average increases by 50%. The stress distribution is affected by the rigidity of the elastic layer. When it increases, the vertical stresses in the sub-rail support decrease nonlinearly, while in traveling concrete they increase nonlinearly.

Flow Regimes in Two-Dimensional Ribbed Diffusers

1975 ◽  
Vol 97 (1) ◽  
pp. 87-96 ◽  
Author(s):  
F. D. Stull ◽  
H. R. Velkoff
Keyword(s):  
Motion Pictures ◽  
Width Ratio ◽  
Cavity Depth ◽  
Velocity Fluctuations ◽  
Wide Range ◽  
Straight Wall ◽  
Throat Width ◽  
Total Divergence ◽  
Hot Film ◽  
Cavity Width

Water table flow visualization tests of a straight wall diffuser and corresponding ribbed diffuser were conducted over a wide range of total divergence angles and diffuser length to throat width ratios. Rib parameters such as inter-rib cavity depth to width ratio, inter-rib cavity width, rib thickness, and number of ribs were varied, as well as rib contour. Motion pictures were obtained of the secondary flow patterns occurring within the inter-rib cavities, and hot film measurements were made to determine the extent of velocity fluctuations induced by the cavities. In general, the addition of ribs increased the no-appreciable stall regime.

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