scholarly journals Theoretical Study on Internal Forces of Primary Support of Tunnel by considering Time Effect

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Zhuangzhi Yang ◽  
Yuqing Wang ◽  
Lin Song ◽  
Xinyu Wang
Keyword(s):  
Analytical Solution ◽  
Rock Pressure ◽  
Internal Force ◽  
Parameter Method ◽  
Tunnel Construction ◽  
Construction Technology ◽  
Supporting Structure ◽  
Internal Forces ◽  
Primary Support ◽  
Over Time

Understanding the internal force distribution and prejudging the weak part of tunnel supporting structure under complicated construction surroundings have become one of the important measures to ensure the safety of tunnel construction. Based on the initial parameter method and field-monitoring results of surrounding rock pressure, the theory of beam on elastic foundation is employed to derive the analytical solution of primary support internal forces. By combining the monitored data of rock pressure in one tunnel, solution of primary support internal force of a section is back analyzed and weak parts of the primary support are analyzed and evaluated. The results show that, after the tunnel excavation is completed, the internal forces of the primary support of the tunnel arch grow larger over time. When θ > 1.0, the internal forces change greatly. The internal force of the primary support decreased to different extents within 2 days after the primary support was applied and then gradually increased over time. Considering the situationality and changeability of the tunnel construction process, the analytical solution for the primary support internal forces of a multicenter arch tunnel proposed in this paper has a strong feasibility in tunnel construction. The conclusions obtained here could provide theoretical support for the design of supporting structure and the optimization of tunnel construction technology.

Analysis of Mechanical Characteristics of Site Experiment on Supporting Structure in Gypsum Breccia Tunnel

2011 ◽  
Vol 261-263 ◽  
pp. 1554-1558
Author(s):  
Ming Lei Sun ◽  
Hong Jian Li ◽  
Zhi Chun Liu
Keyword(s):  
Support System ◽  
Rock Pressure ◽  
Flow Characteristics ◽  
Soft Rock ◽  
Surrounding Rock ◽  
Support Pressure ◽  
Tunnel Support ◽  
Supporting Structure ◽  
Surrounding Rock Pressure ◽  
Primary Support

Gypsum breccia is a kind of soft rock-hard soil, and its component is complex. It has poor cementation, low intensity, strong water reaction, slight expansibility and corrosion. During the tunnel construction of gypsum breccia stratum, the mechanical characteristic of supporting structure is very complex. In order to ensure the safety, reasonability and economy of tunnel support system, it is important to acquire the information on displacement and stress of surrounding rock and support system. Two test sections are selected to monitor. Based on the measured data, the distribution characteristics and the time variation law of different kinds of support in gypsum breccia stratum are studied, including surrounding rock pressure, axial force of rock bolt, support pressure and stress. Such conclusions can be got: When strengthened lining (16# I-steel) of the V-grade surrounding rock used, support system performs well; but the stiffness of primary support is not enough if grillage lining is used. Growth of surrounding pressure is for a long time, which shows that the rock mass has Flow characteristics. Especially the surrounding rock pressure increases continuously. The spatial distribution is random, and the value is large. The stiffness of support system should be strengthened. Most blots at the waist arch are compressive. Bolts at the foot arch and sidewall are under tension. The maximum is nearly 124kN. Contact pressure between primary support and secondary lining at the sidewall is higher than that at arch parts. Steel frame stress comes up to 80% of the maximum within 20 days. Excavation of invert has great influences on stress state of surrounding rock and support system.

Computing Method of Elastic Foundation Beam by MATLAB and its Application

2011 ◽  
Vol 368-373 ◽  
pp. 2760-2763
Author(s):  
Qiang Wang ◽  
Li Yuan Tong
Keyword(s):  
Elastic Foundation ◽  
Bending Moment ◽  
Internal Force ◽  
Beam Deflection ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Supporting Structure ◽  
Internal Forces ◽  
Computing Method ◽  
Elastic Foundation Beam

The elastic foundation beam method is the main method of stress analysis of the supporting structure of the foundation pit, it can easily calculate the internal forces and displacement of the structure, however, the computing method of elastic foundation beam deflection equation is more complicated. So according to the computation principle and method of elastic foundation beam, a computing program has been programmed by MATLAB mathematical software. The program has been applied to compute the internal force and deformation of deep foundation pit of Suzhou subway station. The variation law of displacement and bending moment of supporting structure during excavation has been obtained. The results of the measured and calculated agree well, and the computing results have efficiently guided and optimized supporting design.

Structural Analysis and Internal Force Calculation of Variable Cross-Section Silo

2012 ◽  
Vol 446-449 ◽  
pp. 429-434
Author(s):  
Rui Ting Ma
Keyword(s):  
Cross Section ◽  
Variable Cross Section ◽  
Internal Force ◽  
Variable Cross ◽  
Axially Symmetric ◽  
Internal Forces ◽  
Differential Element ◽  
Symmetric Load ◽  
Force Calculation ◽  
Constant Section

In this paper, the differential element of constant-section silo wall suffering from axially symmetric load is analyzed. From the results of constant-section silo, the author derives the displacements and internal forces of variable cross-section silo. Through a specific example, this paper compares the displacements , internal forces and concrete consumption of variable cross-section silo with those of constant-section silo, and discusses the merits of variable cross-section silo.

scholarly journals Modeling neutral viral mutations in the spread of SARS-CoV-2 epidemics

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0255438
Author(s):  
Vitor M. Marquioni ◽  
Marcus A. M. de Aguiar
Keyword(s):  
Population Genetics ◽  
Analytical Solution ◽  
Genetic Distance ◽  
Mean Field ◽  
Neutral Evolution ◽  
Genetic Evolution ◽  
Epidemic Spreading ◽  
Different Strains ◽  
Over Time ◽  
Good Agreement

Although traditional models of epidemic spreading focus on the number of infected, susceptible and recovered individuals, a lot of attention has been devoted to integrate epidemic models with population genetics. Here we develop an individual-based model for epidemic spreading on networks in which viruses are explicitly represented by finite chains of nucleotides that can mutate inside the host. Under the hypothesis of neutral evolution we compute analytically the average pairwise genetic distance between all infecting viruses over time. We also derive a mean-field version of this equation that can be added directly to compartmental models such as SIR or SEIR to estimate the genetic evolution. We compare our results with the inferred genetic evolution of SARS-CoV-2 at the beginning of the epidemic in China and found good agreement with the analytical solution of our model. Finally, using genetic distance as a proxy for different strains, we use numerical simulations to show that the lower the connectivity between communities, e.g., cities, the higher the probability of reinfection.

scholarly journals Wear of elastic tube with nonuniform coating by rigid bush

2020 ◽  
Vol 162 ◽  
pp. 02002 ◽  
Author(s):  
Kirill E. Kazakov
Keyword(s):  
Analytical Solution ◽  
Special Form ◽  
Special Functions ◽  
Contact Stresses ◽  
Elastic Tube ◽  
Analytical Representation ◽  
Standard Methods ◽  
In Series ◽  
Separate Factor ◽  
Over Time

This article is devoted to the statement and construction of analytical solution of the wearcontact problem for a rigid bush and elastic pipe with a coating in the case when the coating is nonuniform. The presence of nonuniformity leads us to the necessity of constructing a solution in a special form over special functions, since standard methods does not allow us to effectively take into account the complex properties of the coating. Analytical representation for contact stresses under the bush is presented in series with separate factor, which connect with complex properties of coating. This allows provide effective calculation even if these properties are described by rapidly changing or discontinuous functions. It is also shown that contact stresses will be negligible over time.

scholarly journals The Influence of the Internal Forces of the Buckling Modes on the Load-Carrying Capacity of Composite Medium-Length Beams under Bending

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 455 ◽  
Author(s):  
Monika Zaczynska ◽  
Zbigniew Kolakowski
Keyword(s):  
Carrying Capacity ◽  
Internal Force ◽  
Load Carrying Capacity ◽  
Buckling Modes ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Load Carrying ◽  
Internal Forces ◽  
The Individual ◽  
Interactive Buckling

The distribution of the internal forces corresponding to the individual buckling modes of lip-channel (LC) beams is investigated using the Semi Analytical Method (SAM) and the Finite Element Method (FEM). Channel section beams made of 8-layered GFRP (Glass Fiber Reinforced Polymer) laminate with three different layer arrangements were considered. The effect of the internal forces on the non-linear first-order coefficients corresponding to the interactive buckling was also studied. Moreover, distributions of the internal forces corresponded to the loading, leading to structure failure for which the load-carrying capacity was determined. The results indicated a high influence of the Nx internal force component on the buckling loads and load-carrying capacity of the LC-beams.

scholarly journals Effect of Voids behind Lining on the Failure Behavior of Symmetrical Double-Arch Tunnels

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1321 ◽  
Author(s):  
Zhang ◽  
Ye ◽  
Min ◽  
Xu
Keyword(s):  
Service Life ◽  
Earth Pressure ◽  
Internal Force ◽  
Failure Behavior ◽  
Large Section ◽  
Failure Patterns ◽  
Internal Forces ◽  
Tunnel Safety ◽  
Increasing Demand ◽  
The Impact

The presence of voids behind lining seriously affects the safety of the symmetrical double-arch tunnels during service life. It is essential to find out the impact of voids on tunnel safety due to the increasing demand for the construction and maintenance of symmetrical double-arch tunnels. Model tests and numerical analyses were conducted in this research. The results attained were explored including earth pressure, internal force, and lining failure. Results reveal that the presence of voids has a large influence on the internal force in the lining of symmetrical double-arch tunnels, generally in the form of asymmetrical failure patterns of the lining. The failure patterns of the lining are greatly influenced by the size and location of voids with respect to the symmetrical double-arch tunnel circumference. Significant changes in the lining internal forces were found at the areas in the close vicinity of the void whereas a few changes were found at the bottom of the sidewall, the invert, and the central wall far away from the void. The propagation laws of lining cracks of asymmetrical double-arch tunnels are more complicated than symmetrical tunnels with a void behind the central wall. The location of the initial cracking of symmetrical and asymmetrical double-arch tunnels is the same, while the lining failure of the large-section tunnel is the most complicated.

Full-Scale Test and Numerical Simulation of Guided Flexible Protection System under a Blasting Load

2020 ◽  
Vol 26 (2) ◽  
pp. 243-256
Author(s):  
Xin Qi ◽  
Hu Xu ◽  
Zhixiang Yu ◽  
Keqin Sun ◽  
Shichun Zhao
Keyword(s):  
Element Model ◽  
Internal Force ◽  
Full Scale ◽  
Protection System ◽  
Dissipated Energy ◽  
Full Scale Test ◽  
Internal Forces ◽  
Scale Test ◽  
Stage Process ◽  
Blasting Load

ABSTRACT Both active and passive flexible protection methods are effective against rockfalls, but they can result in a secondary hazard due to cumulate rocks inside the structure. To solve this problem, guided flexible protection systems are receiving increased attention in the engineering community. In this study, a full-scale test of a guided flexible protection system was carried out, where the bottom of the mesh was anchored under a blasting load, which can be considered as an extreme loading event related to rockfall hazards. The fluid-solid coupling method was employed in a finite element model to simulate the entire process from the blast to the accumulation of rocks at the bottom of the slope. Based on the experimental and numerical results, a two-stage process was revealed, the internal force and the dissipated energy of each component were compared and analyzed, and the load-transferring path within the system was obtained. The internal forces of the support ropes reached their maximum values in the intercept stage. The posts experienced two peak values, the first of which, in the guide stage, was twice that in the intercept stage. The brake rings were the main energy-dissipating components, and the energy dissipation in the intercept stage was much greater than that in the guide stage. Furthermore, the interaction in terms of collision and friction between the rocks, the slope, and the system was not insignificant, particularly in the guide stage, which can account for more than 40 percent of the consumed energy of the rockfall.

Research of Large LNG Tank Structure

2014 ◽  
Vol 1070-1072 ◽  
pp. 378-382
Author(s):  
Ting Ke Li ◽  
Jia Di Li ◽  
Li Fu Xiao ◽  
Wei Li
Keyword(s):  
Storage Tank ◽  
Material Selection ◽  
Type Material ◽  
Size Optimization ◽  
Construction Technology ◽  
Cryogenic Storage ◽  
Lng Tank ◽  
Over Time

In recent years, the demand of Large LNG storage tank increases over time, but large LNG cryogenic storage tank has not yet established a series of standards and norms, and tank construction technology is also lagging behind. Aiming at the design of the tank form a single, smaller, did not tackle the issue of, this paper mainly discusses from Large LNG tanks, such as type, material selection, structure ,size optimization and so on, which can provide reference for independent construction of storage tank.

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