scholarly journals Numerical Simulation Research of Construction Method for Shallow Buried Large Section Tunnel

2016 ◽  
Vol 10 (1) ◽  
pp. 578-597 ◽  
Author(s):  
Bin Zhu ◽  
Weifeng Kou ◽  
Jiami Xi ◽  
Yanjun Shen
Keyword(s):  
Mechanical Properties ◽  
Side Wall ◽  
Deformation Characteristics ◽  
Large Section ◽  
Simulation Research ◽  
Construction Methods ◽  
Cut Method ◽  
Railway Passenger ◽  
Core Soil ◽  
Stress And Deformation

The background of this paper is based on Deli tunnel of Xi’an to Chengdu Railway passenger dedicated line. In order to compare and optimize this large section tunnel project under different construction methods, General FEA software ANSYS was utilized to simulate and analyze the stress and deformation in 2-D and 3-D. According to the Deli tunnel engineering case, the preliminary comparison and discussion of mechanical properties and deformation characteristics of the construction of bench cut method and two side-wall pilot tunnel method have been carried out. From this simulation, we made the conclusion for different mechanical properties and deformation characteristics in different construction methods. It shows that the two side-wall pilot tunnel method results in less stress and deformation than the bench cut method. Therefore, it is safer to use the former method. The key step for bench cut method is the upper excavation, and the key step for two side-wall pilot tunnel method is the upper core soil excavation. Monitoring and enhanced support of these key areas is imperative to guarantee the smooth construction.

scholarly journals Study on improvement of prefolded energy absorption device to constant resistance and its mechanical properties

2021 ◽  
Vol 104 (3) ◽  
pp. 003685042110368
Author(s):  
Dong An ◽  
Jiaqi Song ◽  
Hailiang Xu ◽  
Jingzong Zhang ◽  
Yimin Song ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Energy Absorption ◽  
Compression Test ◽  
Side Wall ◽  
Concave Side ◽  
Displacement Curve ◽  
Static Compression ◽  
Constant Resistance ◽  
The Impact ◽  
Force Displacement

When the rock burst occurs, energy absorption support is an important method to solve the impact failure. To achieve constant resistance performance of energy absorption device, as an important component of the support, the mechanical properties of one kind of prefolded tube is analyzed by quasi-static compression test. The deformation process of compression test is simulated by ABAQUS and plastic strain nephogram of the numerical model are studied. It is found that the main factors affecting the fluctuation of force-displacement curve is the stiffness of concave side wall. The original tube is improved to constant resistance by changing the side wall. The friction coefficient affects the folding order and form of the energy absorbing device. Lifting the concave side wall stiffness can improve the overall stiffness of energy absorption device and slow down the falling section of force-displacement curve. It is always squeezed by adjacent convex side wall in the process of folding, with large plastic deformation. Compared with the original one, the improved prefolded tube designed in this paper can keep the maximum bearing capacity ( Pmax), increase the total energy absorption ( E), improve the specific energy absorption (SEA), and decrease the variance ( S2) of force-displacement curve.

Mechanics Research on Rock Stress and Deformation of Lancang River Canyon's Large - Scale Dumping Deformation

2013 ◽  
Vol 353-356 ◽  
pp. 318-323
Author(s):  
Song Ye ◽  
Yu Sheng Li ◽  
Qian Guo
Keyword(s):  
Large Scale ◽  
Geological Structure ◽  
Deformation Characteristics ◽  
Deep Part ◽  
Trailing Edge ◽  
Geological Surveys ◽  
Depth Analysis ◽  
Numerical Simulation Methods ◽  
Complex Geological Structure ◽  
Stress And Deformation

This article is based on geological surveys combined with finite element and discrete element numerical simulation methods. In-depth analysis of the complex geological structure, deformation characteristics and stress - deformation problems of dumping rock, we clarify different deformation characteristics of deformable landslide inside, at the bottom and the deep part of trailing edge, and demonstrate the deformation will gradually shift from dumping to shear slip. Potential deformation failure mode will be dumped into the whole sliding - tension, which is controlled by the bottom broken belt, and potential deformation is mainly subject to the bottom fault F207-3 of deformed rock and the dumping broken belt at the deep part of trailing edge.

scholarly journals Deformation Characteristics of Raising, Widening of Old Roadway on Soft Soil Foundation

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2117
Author(s):  
Keke Li ◽  
Wenyuan Xu ◽  
Liang Yang
Keyword(s):  
Lateral Displacement ◽  
Soft Soil ◽  
Ground Surface ◽  
Surface Settlement ◽  
Deformation Characteristics ◽  
Construction Methods ◽  
Ground Surface Settlement ◽  
Total Settlement ◽  
Soil Foundation ◽  
Soft Soil Foundation

The deformation characteristics of a raised and widened old Chinese roadway on a soft soil foundation are investigated in this study via finite element numerical simulation. The rules of ground surface settlement, slope foot lateral displacement, and ground surface settlement evolution of the roadbed under three modes (one-time construction of an eight-lane expressway, widened four-lane expressway, and raised/widened four-lane expressway) are compared. The ground surface settlement process of the eight-lane road foundation, which is formed by first widening and then raising the road, is highly complex. The ground surface settlement curve under the old road foundation increases and then decreases. The lateral displacement of the slope foot also interacts with the widening and raising of the eight-lane roadbed foundation. The range of lateral displacement is 70.05, 42.58, 124.81, 104.54 mm. Fifteen years after construction, the total settlement of the raised and widened roadbed is much larger than that of the one built directly. The total settlement values at the center of the two roadbeds are 297.05 and 234.85 mm, respectively. This manuscript provides data support for the reconstruction and expansion of roads on soft soil foundations, for choosing appropriate construction methods to build roads, and for avoiding major road damage, which is of great significance to the construction of road infrastructure in the future.

scholarly journals Effect of Remelting Temperature and Soaking Time on Microstructure and Mechanical Properties of the Thixoformed Part of Nano-Sized SiCp/7075 Composite

Metals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 709
Author(s):  
Jufu Jiang ◽  
Guanfei Xiao ◽  
Yingze Liu ◽  
Ying Wang ◽  
Xi Nie
Keyword(s):  
Mechanical Properties ◽  
Aluminum Matrix ◽  
Side Wall ◽  
Aluminum Matrix Composite ◽  
Transgranular Fracture ◽  
Composite Part ◽  
Soaking Time ◽  
Ultrasonic Assisted ◽  
Bottom Side ◽  
Side Walls

Semisolid billet of the 7075 aluminum matrix composite reinforced with nano-sized SiC particles was first fabricated by an ultrasonic-assisted semisolid stirring method and rheoforming technology. Then it was thixoformed into a cylinder part under different remelting temperatures and soak times. The effects of the remelting temperature and soaking time on the mechanical properties and microstructure of the thixoformed composite part were investigated. The results show that parts of good quality were thixoformed successfully. The microstructure of the top side wall of the thixoformed part consisted of near spheroidal grains. A large quantity of elongated grains occurred in the medium and bottom side walls and the bottom itself. With increasing remelting temperatures, the size of the solid grains of the thixoformed parts showed a trend of first to increase and afterwards to decrease. High density dislocations were found in the microstructure when the remelting temperatures were 590 °C and 600 °C. When the soaking time was 15 min, the severest deformation occurred in the thixoformed part. High mechanical properties of the thixoformed parts were achieved under conditions such as a remelting temperature between 590 °C and 600 °C and a soaking time between 10 min and 15 min. The fracture mode of the thixoformed part changed from transgranular fracture to intergranular fracture when the remelting temperature was elevated from 580 °C to 610 °C. After the thixoformed parts were treated by T6, the ultimate tensile strength (UTS) and elongation of the side wall were improved to 552 MPa and 7.9%, respectively. Dispersed MgZn2 precipitates created by T6 heat treatment led to an improvement of the mechanical properties.

scholarly journals The Deformation Characteristics, Fracture Behavior and Strengthening-Toughening Mechanisms of Laminated Metal Composites: A Review

Metals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 4 ◽  
Author(s):  
Kuan Gao ◽  
Xin Zhang ◽  
Baoxi Liu ◽  
Jining He ◽  
Jianhang Feng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Fracture Behavior ◽  
Tensile Fracture ◽  
Matrix Composites ◽  
Deformation Characteristics ◽  
Toughening Mechanisms ◽  
Metal Composites ◽  
Fracture Elongation

Multilayer metal composites have great application prospects in automobiles, ships, aircraft and other manufacturing industries, which reveal their superior strength, toughness, ductility, fatigue lifetime, superplasticity and formability. This paper presents the various mechanical properties, deformation characteristics and strengthening–toughening mechanisms of laminated metal matrix composites during the loading and deformation process, and that super-high mechanical properties can be obtained by adjusting the fabrication process and structure parameters. In the macroscale, the interface bonding status and layer thickness can effectively affect the fracture, impact toughness and tensile fracture elongation of laminated metal matrix composites, and the ductility and toughness cannot be fitting to the rule of mixture (ROM). However, the elastic properties, yield strength and ultimate strength basically follow the rule of mixture. In the microscale, the mechanical properties, deformation characteristics, fracture behavior and toughening mechanisms of laminated composites reveal the obvious size effect.

scholarly journals Construction of Wood-Based Lamella for Increased Load on Seating Furniture

Forests ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 525 ◽  
Author(s):  
Nadežda Langová ◽  
Roman Réh ◽  
Rastislav Igaz ◽  
Ľuboš Krišťák ◽  
Miloš Hitka ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Modulus Of Rupture ◽  
The Finite Element Method ◽  
Ultimate State ◽  
Overweight People ◽  
Number Of Layers ◽  
Fem Method ◽  
Stress And Deformation

The research on population shows that the count of overweight people has been constantly growing. Therefore, designing and modifying utility items, e.g., furniture should be brought into focus. Indeed, furniture function and safety is associated with the weight of a user. Current processes and standards dealing with the design of seating furniture do not meet the requirements of overweight users. The research is aimed at designing flexible chairs consisting of lamellae using the finite element method (FEM). Three types of glued lamellae based on wood with different number of layers and thickness were made and subsequently, their mechanical properties were tested. Values for modulus of elasticity and modulus of rupture were used to determine stress and deformation applying the FEM method for modelling flexible chairs. In this research, the methodology for evaluating the ultimate state of flexible chairs used to analyse deformation and stability was defined. The analysis confirms that several designed constructions meet the requirements of actual standards (valid for the weight of a user up to 110 kg) but fail to meet the requirements for weight gain of a population.

Fluid-Solid Coupling Analysis the Plastic Damage of the Surrounding Rock under the Influence of Confined Water Pressure and Mining Disturbance

2012 ◽  
Vol 616-618 ◽  
pp. 533-537
Author(s):  
Chun Hu Zhao
Keyword(s):  
Water Pressure ◽  
Coupling Model ◽  
Surrounding Rock ◽  
Deformation Characteristics ◽  
Concentration Zone ◽  
Confined Water ◽  
Rock Stress ◽  
Plastic Damage ◽  
Mining Disturbance ◽  
Stress And Deformation

In order to anlysis the rock deformation characteristics in influence of mining disturbances, water pressure and crustal stress, a multi-physics coupling model is created by Comsol4.2a in this paper. By debugging mining steps and water pressure, the model simulated rock stress and deformation characteristics.the results showed that: (1)the water pressure is fixed conditions, the plastic damage scope in stress concentration zone where was formed by mining disturbanceis were greater than the mining floor,and with an extension of the scope of mining, the scope of plastic failure zone in the rock surrounding which including the vertical and horizontal was increased; (2) Stope width is fixed conditions,with the water pressure increases, resulting in the surrounding rock mechanical strength decrease, and increase the scope of the plastic collapse and plastic damage within thefault zone intensified.

scholarly journals Experimental Study on the Creep Behavior of Red Sandstone under Low Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Yongjun Song ◽  
Leitao Zhang ◽  
Huimin Yang ◽  
Jianxi Ren ◽  
Yongxin Che
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Deformation Characteristics ◽  
Red Sandstone ◽  
Rock Samples ◽  
Uniaxial Creep ◽  
Deformation Properties ◽  
Accelerated Creep ◽  
Different Temperatures

In cold regions, the deformation characteristics and long-term mechanical properties of rocks under low-temperature conditions are considerably different from those in other regions. To study the deformation characteristics and long-term mechanical properties of rocks in a low-temperature environment and the effect of different temperatures, we perform a multilevel loading-unloading uniaxial creep test on red sandstone samples and obtain the creep curves at different temperatures (20°C, −10°C, and −20°C). The results demonstrate that the total strain at each temperature can be divided into instantaneous and creep strains; the instantaneous strain includes instantaneous elastic and plastic strains, and the creep strain includes viscoelastic and viscoplastic strains. Temperature has a significant effect on the deformation properties of red sandstone. A decrease in temperature reduces the instantaneous and creep deformations of the rocks at all levels of stress. In addition, a decrease in temperature exponentially attenuates the total creep and viscoplastic strains of the rocks. 0°C is a critical point for the reduction of the total creep and viscoplastic strains of the rocks. When the temperature is greater than 0°C, the total creep and viscoplastic strains of the rocks decrease rapidly and linearly with decrease in temperature; however, when the temperature is less than 0°C, the decrease in the total creep and viscoplastic strains of the rocks is slow. The steady-state creep rate of the rock samples decreases with decrease in temperature, whereas the creep duration increases with decrease in temperature, especially in the case of the accelerated creep stage. The accelerated creep durations of the rock samples S4 (20°C) and S7 (–10°C) are 0.07 h and 0.23 h, respectively.

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