scholarly journals Deformation Characteristics of the Surrounding Rock of a Six-Lane Multiarch Tunnel under Different Excavation Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Lina Luo ◽  
Gang Lei ◽  
Haibo Hu
Keyword(s):  
Three Dimensional ◽  
Class Ii ◽  
Surrounding Rock ◽  
Displacement Rate ◽  
Construction Technology ◽  
Deformation Characteristics ◽  
Highway Traffic ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Secondary Lining

Highway tunnel plays an increasingly prominent role in the development of high-grade highway traffic in mountainous countries or regions. Therefore, it is necessary to explore the deformation characteristics of the surrounding rock of a six-lane multiarch tunnel under different excavation conditions. Using the three-dimensional indoor model test and finite element analysis, this paper studies the dynamic mechanical behavior of a six-lane construction, reveals the whole process of the surrounding rock deformation process of class II surrounding rock under different excavation conditions, and puts forward the best construction and excavation method. The results show that the maximum displacement rate of excavation scheme III is the largest, and the maximum displacement rate of excavation scheme I is basically the same as that of excavation scheme II. Therefore, in terms of controlling the displacement rate of the surrounding rock, the effect of excavation scheme I is basically the same as that of excavation scheme II, while that of excavation scheme III is poor. In terms of construction technology, scheme II is simpler than scheme I and can ensure the integrity of the secondary lining. Therefore, in class II surrounding rock of the supporting project, it is recommended to adopt scheme II for construction.

Analysis of Plastic Strain between Substrate and Micro-Cantilever under Different Deformation Characteristics

2013 ◽  
Vol 477-478 ◽  
pp. 21-24
Author(s):  
Hui Kai Gao ◽  
Jian Meng Huang
Keyword(s):  
Plastic Strain ◽  
Rough Surface ◽  
Three Dimensional ◽  
Equivalent Plastic Strain ◽  
Adhesive Contact ◽  
Contact Model ◽  
Deformation Characteristics ◽  
Element Analysis ◽  
Flat Substrate ◽  
Micro Cantilever

The contact between substrate and micro-cantilever simplified as an ideal flat substrate contact with a micro-cantilever rough surface. A three-dimensional adhesive contact model was established on isotropic rough surfaces exhibiting fractal behavior, and the equivalent plastic strain was discussed using the finite element analysis. The maximum equivalent plastic strain and its depth were presented with the different paths of rough solid when loading. The result show that the equivalent plastic strain versus different depth which at different locations showed different laws, in the top area of the asperities versus different depth, the maximum equivalent plastic strain occurs in the subsurface range about 0.5μm from the surface or on the surface. In addition, with different deformation characteristics, the degree of the equivalent plastic strain was different.. The contact model between micro-cantilever rough surface and flat substrate will lay a foundation to further research on the substance of the process of friction and wear.

scholarly journals New Construction Technology of a Shallow Tunnel in Boulder-Cobble Mixed Grounds

2020 ◽  
Vol 2020 ◽  
pp. 1-20 ◽  
Author(s):  
Tong Liu ◽  
Yujian Zhong ◽  
Zhihua Feng ◽  
Wei Xu ◽  
Feiting Song ◽  
...  
Keyword(s):  
Surrounding Rock ◽  
Construction Technology ◽  
Construction Process ◽  
Tunnel Excavation ◽  
Supporting System ◽  
Highway Tunnel ◽  
Bulk Medium ◽  
New Construction ◽  
Secondary Lining ◽  
Design And Construction

As a typical granular bulk medium, problems are common in boulder-cobble mixed grounds, such as easy collapse and instability and difficult effective support for large-section tunnel excavation. Tunnels constructed in BCM grounds are rare still, and there is a big gap between the design and construction of tunnels. Based on the Nianggaicun highway tunnel crossing the BCM grounds, the construction technology of tunnel in BCM grounds is studied by means of literature investigation and field survey. Here are the main conclusions: the overall deformation of surrounding rock is quite small; the pressure distribution of surrounding rock is small and loose pressure is dominant, and the safety reserve of secondary lining is large. The deformation process of surrounding rock concentrates on the construction stage. During the construction process, there are many problems, such as serious overexcavation, difficulty of bolt penetration, and continuous rock fall. In this paper, a three-bench complementary cyclic excavation method is proposed, which replaces the original CD and CRD methods. Meanwhile, the supporting system is optimized. The results show that the disturbance of surrounding rock is reduced, while the safety of construction process and the reliability of structure are increased. The new excavation method and optimized supporting system are expected to fill the gap between design and construction of tunnel in BCM grounds and provide reference for construction of such tunnels in the future.

Optimum Design of Engine Test Bench Based on Finite Element Analysis

2011 ◽  
Vol 338 ◽  
pp. 255-258 ◽  
Author(s):  
Shao Bo Wen
Keyword(s):  
Test Bench ◽  
Excitation Frequency ◽  
Three Dimensional ◽  
Natural Vibration Frequency ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Vehicle Engine ◽  
Stress And Deformation ◽  
The Stability ◽  
Engine Excitation

A test bench of vehicle engine is designed and the three-dimensional solid model is established in UG software. Then the model is imported into ANSYS software to conduct static stress analysis, the stress and deformation distribution of test bench are obtained, referenced the results and the bracket are optimized to improve support ability, the maximum stress and the maximum displacement of test bench decreased 66.9% and 76.9%, respectively. Lastly modal analysis of test bench is performed, the chassis base is strengthen design according to the first-order mode shape, then the first natural vibration frequency is heightened 91.0%, it is far away from the engine excitation frequency range, the stability of test bench is enhanced.

Three-Dimensional Finite Element Analysis on the Bearing Capacity of Bucket Foundation with Different Ratios of Diameter to Height

2014 ◽  
Vol 488-489 ◽  
pp. 689-695
Author(s):  
Shuai Liu ◽  
Wen Bai Liu ◽  
Liang Yang
Keyword(s):  
Bearing Capacity ◽  
Three Dimensional ◽  
Vertical Displacement ◽  
Ultimate Bearing Capacity ◽  
Displacement Curve ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Bucket Foundation ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The ABAQUS software is used for simulating the vertical bearing capacity of bucket foundation of different ratios of diameter to height and the analysis for the stress and displacement distribution and load-displacement curve. When the bucket foundation is under pressure, the vertical stress of the soil distribution changes from the bottom to the top, and then spreads to most part of the soil in the bucket foundation. The vertical displacement of the soil develops from the top of foundation and spreads inside, then expands to the outside range, the maximum displacement occurs both at the bottom and inside. According to the analysis of the ultimate bearing capacity of the bucket foundation, it could be found that when the height of the bucket foundation remains unchanged, the ultimate bearing capacity increases with the increasing ratio of diameter to height. If the ratio of diameter to height is less than 1.2, the ultimate strength increases significantly. If the ratio of diameter to height is greater than 1.2, the increasing speed of the ultimate bearing capacity changes slowly. When the diameter of the bucket foundation is constant, the ultimate bearing capacity decreases as the ratio of diameter to height gradually increases, and it decreases at a homogeneous speed. So the ratio of diameter to height 1.2 can be used as the optimum point of the ratio of diameter to height of the bucket foundation.

Crack Mechanism, Temperature Control, and Anti-Cracking Measures of Sluice

2013 ◽  
Vol 405-408 ◽  
pp. 1217-1220
Author(s):  
Zhen Hong Wang ◽  
Guo Xin Zhang ◽  
Shu Ping Yu
Keyword(s):  
Temperature Control ◽  
Three Dimensional ◽  
Control Measures ◽  
Construction Technology ◽  
Element Analysis ◽  
Engineering Construction ◽  
Simulation Calculation ◽  
Project Construction ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

To address the problem of sluice concrete easily cracking during construction, this study introduces the crack mechanism of concrete structures. Temperature differences and constraints are the main causes of cracks. Anti-cracking measures should focus on optimizing concrete mixing ratio and improving construction technology. Using simulation calculation to model the actual construction process and temperature control measures, this study analyzes the causes of crack and selects timely and reasonable temperature control measures, which are necessary links in engineering construction. A three-dimensional finite element analysis was conducted for a huge concrete sluice structure. The causes of cracks are discussed, and timely and feasible anti-cracking measures are proposed to provide technical support for project construction.

scholarly journals Evaluation of Efficacy of Various Implants in Maxillary Arch Distalization - A Finite Element Analysis

2020 ◽  
Vol 10 (1) ◽  
pp. 44-54
Author(s):  
Sneha Sanap ◽  
Vinit Swami ◽  
Amol Patil ◽  
Shailesh Deshmukh ◽  
Veera Bhosale
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Effective Means ◽  
Three Dimensional ◽  
Element Model ◽  
Class Ii ◽  
Maximum Amount ◽  
Element Analysis ◽  
Second Molar ◽  
Maxillary Arch

Introduction: Orthodontic correction of Angle’s class II molar relation has, for long, been one of the challenges in orthodontics, with various researchers attempting to correct the class II molar relationship by diverse methods. One of the techniques that has gained popularity in recent times is maxillary arch distalization by infrazygomatic screws and miniscrews. The objective of the study is to measure and compare the amount of maxillary arch distalization and its effects, on adjacent teeth, by varying the positions of mini-implants by Finite Element Analysis. Materials & Method: A standard three-dimensional finite element model was constructed to simulate the maxillary teeth, periodontal ligament, and alveolar process. In this study, three models were prepared. Model-1: The (miniscrews) were placed between upper first and second premolar, and between second premolar and first molar bilaterally. Model-2: Infrazygomatic screws was placed between upper first and second molar bilaterally. Model-3: Infrazygomatic screws was placed on the mesio-buccal root of upper first molar bilaterally. The displacement of each tooth was calculated on x, y, and z axes when 200 gm of force was applied on each side. Result: Maximum amount of maxillary arch distalization was seen when infrazygomatic screws placed between upper first and second molar in model-2. Whereas maximum amount of maxillary arch intrusion and less distalization was observed when miniscrews placed between upper first premolar and second premolar and in between second premolar and upper first molar in model-1. The difference was statistically significant (p=0.005*). There was no bucco-palatal rotation of teeth observed among all three finite element models. Conclusion: Thus infrazygomatic screws and miniscrews are the effective means of maxillary arch distalization for the correction of Class II malocclusion.

Three Dimensional Finite Element Interference Contact Analysis about Cone Screw and Bush of Opposed Biconinal Cone Screw High-Pressure Seawater Hydraulic Pump

2012 ◽  
Vol 197 ◽  
pp. 174-178 ◽  
Author(s):  
Xin Hua Wang ◽  
Xiu Xia Cao ◽  
Shu Wen Sun ◽  
Yan Gao
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Displacement Vector ◽  
Three Dimensional ◽  
Von Mises Stress ◽  
Hydraulic Pump ◽  
Maximum Displacement ◽  
Element Analysis ◽  
Factors Affecting ◽  
Von Mises

The main components of the opposed biconinal cone screw high-pressure seawater hydraulic pump is the rubber bush and metal cone screw, and the interaction of the bush and cone screw is one of the main factors affecting the novel pump performance. The deformation and stress of the bush and cone screw under the initial interference is analyzed by the nonlinear finite element analysis. The analysis shows that: under the effect of the initial interference, large displacement is present to the radial surface of the cone screw, and the displacement of the radial surface mainly affects the displacement vector sum of the cone screw, and the deformation decreases gradually from the middle to the ends of the cone screw, while the cone screw is bending; the deformation in three direction of the bush is close to each other, but the location of the maximum displacement in each direction is different; with the shrink range increasing, the deformation of the cone screw and bush increases, but the deformation of the cone screw is much smaller than that of bush, so the deformation of the bush mainly affects the seal between the cone screw and bush, and the shrink range between the cone screw and bush decreases because of the deformation of the bush. Over the role of the interference force, the maximum von mises stress of the cone screw is an order larger than that of bush, and the maximum von mises stress both increases with the shrink range increasing; although shrink range is different, the location of the maximum von mises about the cone screw and bush is the same.

scholarly journals Small Pilot Tunnel Advance and Step Reverse Expansion in Super-Large-Section Tunnel Excavation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Bole Sun ◽  
Xiaorong Tang ◽  
Yongyi He ◽  
Mingnian Wang
Keyword(s):  
Production Efficiency ◽  
Expansion Method ◽  
Surrounding Rock ◽  
Construction Technology ◽  
Construction Time ◽  
Engineering Project ◽  
Large Section ◽  
Maximum Displacement ◽  
Tunnel Support ◽  
In Situ Conditions

Collapse of the vault and numerous other safety accidents often occur during the construction process of large-section tunnels. The utilization of a small pilot tunnel and a step reverse expansion construction methodology is proposed based on conventional construction methods to explore safe construction technology. First, a theoretical analysis combined with on-site monitoring parameters was conducted. It showed that the maximum displacement of the tunnel surrounding rock was 0.027 m during the elastic stage and increased to 0.031 m during the strength limit stage. The overall surrounding rock deformation does not have a noticeable impact on tunnel safety. A numerical simulation model of the small pilot tunnel advancement and step reverse expansion method was established. Simulation results showed that the first two excavation steps caused 89.6% of the total overlining strata subsidence, and the use of a small pilot tunnel advancement and step reverse expansion method can enhance the tunnel support. The tunnel surrounding rock was adequately stabilized after using this excavation method and provides the in-situ conditions for expanding the pilot tunnel to the large-section tunnel. The proposed method was adopted in an actual engineering project. It protected the subsequent construction of the main tunnel and decreased construction time, saving construction costs while ensuring safety, reducing construction risks, and improving production efficiency. This research can guide similar tunneling projects.

scholarly journals Influence of Sagittal Root Positions on the Stress Distribution Around Custom-made Root-analogue Implants: A Three-dimensional Finite Element Analysis

2021 ◽  
Author(s):  
Chunping Lin ◽  
Hongcheng Hu ◽  
Junxin Zhu ◽  
Yuwei Wu ◽  
Qiguo Rong ◽  
...  
Keyword(s):  
Stress Concentration ◽  
Three Dimensional ◽  
Class Ii ◽  
Class I ◽  
Von Mises Stress ◽  
Class Iii ◽  
Element Analysis ◽  
Custom Made ◽  
Root Position ◽  
Von Mises

Abstract Background: Stress concentration may cause bone resorption even lead to the failure of implantation. This study was designed to investigate whether a certain sagittal root position could cause stress concentration around maxillary anterior custom-made root-analogue implants via three-dimensional finite element analysis.Methods: Six models were constructed and divided into two groups. The smooth group included models of unthreaded custom-made implants in Class I, II or III sagittal root positions. The threaded group included models of reverse buttress-threaded implants in the three positions. Stress distributions under vertical and oblique loads of 100 N were analyzed.Results: Stress concentrations around the labial lamella area were more prominent in the Class I position than in the Class II and Class III positions under oblique loading. Under vertical loading, the most obvious stress concentration areas were the labial lamella and palatal apical areas in the Class I and Class III positions, respectively. Stress was relatively distributed in the labial and palatal lamellae in the Class II position. The maximum von Mises stress in the bone around the custom-made root-analogue implants in this study was lower than around traditional implants reported in the literature. Additionally, compared to the smooth group, the threaded group showed lower von Mises stress in the bone around the implants.Conclusions: The sagittal root position affected the von Mises stress distribution around custom-made root-analogue implants. There was no certain sagittal root position that could cause excessive stress concentration around the custom-made root-analogue implants. Among the three sagittal root positions, the Class II position would be the most appropriate site for custom-made root-analogue implants.

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