scholarly journals Numerical Analysis on the Behavior of Existing Tunnels Subjected to the Undercrossed Shield Tunneling at a Small Proximity

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Chunqing Fu ◽  
Yuchun Gao
Keyword(s):  
Finite Element ◽  
Friction Angle ◽  
Element Model ◽  
Shield Tunnel ◽  
Soil Parameters ◽  
External Diameter ◽  
Equivalent Stiffness ◽  
Shield Tunneling ◽  
Stiffness Model ◽  
Vertical Spacing

Shield excavation in a proximity to existing tunnels inevitably causes deformation and stress change of the adjacent tunnels. Based on the project of new metro line in Beijing where the shield tunnel was constructed under existing tunnel, a modified equivalent stiffness model for the existing tunnel is proposed. Based on this, a three-dimensional finite element is established, and subsequently the proposed modified equivalent stiffness model and the previous model are implemented into the finite element model (FEM), respectively, and then the effectiveness of it is verified through comparison with the field measurements. The results indicate that the modified equivalent stiffness model has excellent agreement with the monitoring value. The impacts of key parameters including undercrossing angle, vertical spacing, and soil parameters on the crown settlement of the existing tunnel are investigated. The maximum settlement of the existing tunnel crown decreases as the undercrossing angle increases. The decease of vertical spacing between the newly constructed tunnel and the existing tunnel leads to an increase of the peak value of crown settlement. As for the soil parameters, friction angle φ is the dominant parameter affecting crown settlement of the existing tunnel whereas the cohesion c is least influential. During the process of route selection, it is suggested to keep the vertical spacing between new tunnel and the existing tunnel greater than the external diameter of the new metro tunnel. For the situation of undercrossing an existing tunnel within an extremely small clearance, it is recommended to strengthen the soil as necessary.

3D Finite Element Simulation on During Shield Tunneling

2011 ◽  
Vol 90-93 ◽  
pp. 1950-1955
Author(s):  
Yi Liu ◽  
Ji Shun Li ◽  
Bao Lian Wang
Keyword(s):  
Finite Element ◽  
Numerical Procedure ◽  
Ground Surface ◽  
Element Model ◽  
Small Strain ◽  
Ground Movement ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Shield Tunneling ◽  
Epb Shield

Based on the comprehensive analysis on the primary components of ground movement associated with earth pressure balance (EPB) shield tunneling, a three-dimensional nonlinear finite element model for simulating EPB shield tunneling is proposed. The proposed modeling techniques are applied to simulate a tunneling project. The distributions of soil displacement on the ground surface associated with the advance-ment process of shield tunnel are analyzed. According to the comparisons of numerical results with field measurements, the proposed numerical procedure is found to be an effective approach for predicting the deformation dun to shield tunneling. The further analysis shows that the computed results of the small-strain constitutive model are more reasonable, and the small-strain mechanical behaviors of soils should be taken into account

Numerical Analysis of Metro Station Construction by Large-Diameter Shield and Pile-Beam-Arch Method

2011 ◽  
Vol 368-373 ◽  
pp. 2711-2715 ◽  
Author(s):  
De Yun Ding ◽  
Xiu Ren Yang ◽  
Wei Dong Lu ◽  
Wei Ning Liu ◽  
Mei Yan ◽  
...  
Keyword(s):  
Ground Deformation ◽  
Large Diameter ◽  
Element Model ◽  
Construction Method ◽  
Shield Tunnel ◽  
Outer Diameter ◽  
Shield Tunneling ◽  
Metro Station ◽  
Dimensional Finite Element ◽  
New Construction

In more and more complicated urban building environment, a new construction method that metro engineering is constructed by large-diameter shield and shallow mining method can be regarded as a great attempt in China. By taking the Gaojiayuan station of Beijing metro line 14 as an engineering background, the main construction steps for the platform of the metro station built by a large-size shield with an outer diameter of 10 m and the Pile-Beam-Arch (PBA) method are introduced. Based on the soil-structure interaction theory, a two-dimensional finite element model is used to simulate the shield tunneling and the platform construction by the PBA method to enlarge the shield tunnel. The ground deformation and structural stress of the platform are predicted. The numerical results can be regarded as a valuable reference for the application of the new construction method in Beijing metro line 14.

An Effective Method for Determining Finite Element Model Parameters of Rotor Elastic Support System

2011 ◽  
Vol 141 ◽  
pp. 191-197
Author(s):  
Yong Xing Wang ◽  
Jiang Yan ◽  
Sheng Ze Wang
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Support System ◽  
Structural Parameters ◽  
Element Model ◽  
Elastic Support ◽  
Asymmetric Structure ◽  
Model Parameters ◽  
Equivalent Stiffness ◽  
Rolling Ball

A finite element model of the elastic support rotor system based on the corresponding experimental model was established. According to the principle of two types of model with an equal first order critical speed, the equivalent stiffness and damping of a rolling ball bearing support system with rubber rings determined by experiment were transferred into the finite element model. Then, the dynamic behavior of rotor systems with symmetric and asymmetric structure, different support system stiffness and support span were calculated and analyzed respectively. At last, the influence of the rotor structural parameters on the equivalent stiffness of elastic bearing support system obtained by experiment was pointed out.

Stiffness Model of the Armature Assembly in a Jet Pipe Pressure Servo Valve

2020 ◽  
Author(s):  
Yaobao Yin ◽  
Chengpeng He ◽  
Jing Li
Keyword(s):  
Finite Element ◽  
Complex Structure ◽  
Small Deformation ◽  
Element Model ◽  
Continuity Condition ◽  
The Finite Element Method ◽  
Servo Valve ◽  
Linear Elastic ◽  
Stiffness Model ◽  
Static Performance

Abstract The armature assembly of the jet pipe pressure servo valve plays an important role in connecting the torque motor and the jet pipe amplifier. A stiffness model of its complex structure is very necessary for analyzing the dynamic/static performance of the jet pipe pressure servo valve. At the present work, the component parts in the armature assembly are simplified into linear elastic beams. The simplified armature assembly is a fourfold statically indeterminate structure under the premise of small deformation. The unknown forces and moments are solved by using the section continuity condition as the additional supplement equation, and the functional relationship between the electromagnetic torque produced from the torque motor and the armature rotation angle /the nozzle displacement is derived based on the Castigliano's Theorem. The finite element model of the armature assembly is also established to calculate the deformation under different loads and different spring tube lengths. The simulated displacements with the finite element method are consistent with the theoretical results. The experimental results of the recovery pressure of the jet pipe valve verified the theoretical model. The proposed stiffness calculation method can be used as a reference for designing and optimizing the armature assembly in the jet pipe pressure servo valve.

Numerical Simulation on the Surface Subsidence Effect during Shield Tunneling Construction

2011 ◽  
Vol 299-300 ◽  
pp. 110-113
Author(s):  
Hai Xia Sun ◽  
Hai Yu Wu ◽  
Si Li Chen
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Surface Deformation ◽  
Influence Factors ◽  
Surface Subsidence ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Finite Element Program ◽  
Element Program ◽  
Numerical Simulation Methods

Against the background of shenyang subway shield tunnel construction, the method of numerical simulation methods are used to analyze the factors of surface subsidence caused by shield construction comprehensively, and the universal finite element program ABAQUS is used to establish mechanical model depended on comprehensive consideration the influence factors of soil warehouses pressure, seepage and groundwater. A dynamic finite element simulation of shield advance process and conclude the surface deformation rule of soil are studied.

Numerical investigation into the effect of ballast properties on buckling of continuously welded rail (CWR)

2020 ◽  
pp. 095440972096579
Author(s):  
Fatemeh Khatibi ◽  
Morteza Esmaeili ◽  
Saeed Mohammadzadeh
Keyword(s):  
Finite Element ◽  
Discrete Element Method ◽  
Finite Element Model ◽  
Field Data ◽  
Friction Angle ◽  
Element Model ◽  
Sensitivity Analyses ◽  
Track Stiffness ◽  
Dem Analysis ◽  
Continuously Welded Rail

In this paper, the effect of ballast properties including ballast depth, shoulder width, shoulder height, inter particle friction angle and ballast porosity on track buckling capacity are investigated numerically using discrete element method (DEM) analysis. First, a Single Tie Push Test (STPT) is simulated using DEM and the results are validated with field data. Then a sensitivity analyses is carried out. To investigate the effect of ballast properties on buckling capacity, the STPT responses according to the DEM analysis are introduced as a lateral track stiffness into a finite element model of continuously welded rail track, and a thermal buckling simulation is performed. The results show a significant effect of ballast porosity on buckling temperature.

Modelling the applied vertical stress and settlement relationship of shallow foundations in saturated and unsaturated sands

2011 ◽  
Vol 48 (3) ◽  
pp. 425-438 ◽  
Author(s):  
Won Taek Oh ◽  
Sai K. Vanapalli
Keyword(s):  
Finite Element ◽  
Bearing Capacity ◽  
Characteristic Curve ◽  
Friction Angle ◽  
Vertical Stress ◽  
Shallow Foundations ◽  
Surface Settlement ◽  
Soil Parameters ◽  
Finite Element Analyses ◽  
Unsaturated Sands

The bearing capacity and settlement of foundations are determined experimentally or modelled numerically based on conventional soil mechanics for saturated soils. In both methods, bearing capacity and settlement are estimated based on the applied vertical stress versus surface settlement relationship. These methods are also conventionally used for soils that are in an unsaturated condition, ignoring the contribution of matric suction. In this study, a methodology is proposed to estimate the bearing capacity and settlement of shallow foundations in unsaturated sands by predicting the applied vertical stress versus surface settlement relationship. The proposed method requires soil parameters obtained under only saturated conditions (i.e., effective cohesion, effective internal friction angle, and modulus of subgrade reaction from model footing test) along with the soil-water characteristic curve (SWCC). In addition, finite element analyses are undertaken to simulate the applied vertical stress versus surface settlement relationship for unsaturated sands. The proposed method and finite element analyses are performed using an elastic – perfectly plastic model. The predicted bearing capacities and settlements from the proposed method and finite element analyses are compared with published model footing test results. There is good agreement between measured and predicted results.

Design and Simulation of the New Bionic Soil Extruding Head

2012 ◽  
Vol 479-481 ◽  
pp. 457-461
Author(s):  
Dong Hui Chen ◽  
Xin Lu ◽  
Xing Wang Chai ◽  
Bao Gang Wang ◽  
Hong Xia Guo ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Simulation Model ◽  
Element Model ◽  
Maximum Force ◽  
Soil Parameters ◽  
Drilling Depth ◽  
Finite Element Software ◽  
Changing Trends ◽  
The Finite Element Model

In this paper，soil parameters and the collected data were tested and processed, and the changing trends of force with drilling depth were obtained and the maximum force applying to the working components was picked up. Compared with the smooth working component, the force applying to the unsmooth working components is smaller. Some parameters needed in Drucker-Prager soil model were measured and modified according to the basic tests. The simulation model was built in the finite element software -ANSYS. The simulation result is consistent with the actual testing result, which confirms the finite element model is correct .

Finite element simulation and experimental analysis of robotic boring based on an approach of equivalent stiffness

2017 ◽  
Vol 232 (11) ◽  
pp. 2008-2018 ◽  
Author(s):  
Guifeng Wang ◽  
Huiyue Dong ◽  
Yingjie Guo ◽  
Yinglin Ke
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Element Model ◽  
Equivalent Stiffness ◽  
Element Simulation ◽  
Cutting Force Components ◽  
Mass Spring ◽  
Robotic Boring

Robotic boring is an effective way to implement finish machining of intersection holes. However, to a certain extent, its application is limited due to the low rigidity of the robot, whose stiffness brings on high vibration levels. In this study, a new approach based on an equivalent stiffness is proposed to gain a fundamental understanding for the cutting mechanism and vibration performance of a robotic boring system. In the approach, the robotic boring system in one direction is regarded as a mass–spring–damping unit according to the structure characteristics of the robot. Thus, the whole robotic boring system is equivalent to a mass–spring–damping group in three-dimensional space. The stiffness and natural frequency of the robot system were measured by stiffness identification and a modal test on an ABB IRB 6600-175/2.55 robot. An equivalent three-dimensional finite element model based on this approach was established to simulate the robotic boring process, and a verification experiment was conducted to determine the accuracy of the finite element simulation. The results show that the simulated cutting force components and the amplitude in the feed direction are in good agreement with the experiment under different cutting conditions, and this proposed approach is feasible.

Analysis of the Longitudinal Settlements of Tunnel with the Soft Layers in Substratum Soil

2012 ◽  
Vol 461 ◽  
pp. 510-512
Author(s):  
Qian Yang
Keyword(s):  
Finite Element ◽  
Soft Soil ◽  
Element Model ◽  
Linear Functions ◽  
Shield Tunnel ◽  
Soft Layer ◽  
3D Finite Element ◽  
Operation Conditions ◽  
Calculation Results ◽  
Coulomb Model

The 3D finite element model on the interactions between soil and lining was established based on the Mohr-Coulomb Model. Different operation conditions were used to analyze influence on shield tunnel settlement in soft soil, such as difference in properties of substratum soil of tunnels. The deformation discipline of tunnels was achieved. The calculation results show that: the maximal settlement is linear functions of the elastic modulus of the soft layer.

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