Grouting Pressure Distribution Model for the Simultaneous Grouting of Shield Tunneling While Considering the Diffusion of Slurry

2020 ◽  
pp. 793-809
Author(s):  
Zhong Zhou ◽  
Zhuangzhuang Liu ◽  
Binran Zhang ◽  
Wenyuan Gao ◽  
Chengcheng Zhang
Keyword(s):  
Pressure Distribution ◽  
Distribution Model ◽  
Shield Tunneling ◽  
Grouting Pressure

The Research of Backfill Grouting Pressure in Shield Tunneling

2012 ◽  
Vol 446-449 ◽  
pp. 2240-2245
Author(s):  
Jin Li Qiao ◽  
Yong Li Fan ◽  
Bo Liu ◽  
Yan Ping Zhang ◽  
Yan Yan Li
Keyword(s):  
Shield Tunneling ◽  
Grouting Pressure

Torque Modelling and Experiment in Pelleting Process of Rotated Roll Forming

2012 ◽  
Vol 184-185 ◽  
pp. 609-613
Author(s):  
Kai Wu ◽  
Yu Sun ◽  
Bin Bin Peng
Keyword(s):  
Pressure Distribution ◽  
Powder Material ◽  
Structural Design ◽  
Experimental Results ◽  
Distribution Model ◽  
Roll Forming ◽  
Testing System ◽  
Force Model ◽  
Optimal Structural Design

First the extruding force model of isotropic powder material passing through the die hole in pelleting process was founded, then the pressure distribution model in the extruding areas was built. Based on the two models, the torque model in pelleting process of rotated roll forming was developed. The experiments were carried out on the special designed pellet mill and the wireless torque testing system was used to analysis the torque datum. It is shown the computing datum is very close to the experimental results. The researches are helpful to the optimal structural design, energy consume reduction and proper use of the pellet mill in practice.

scholarly journals Squeeze Film Dampers Executing Small Amplitude Circular-Centered Orbits in High-Speed Turbomachinery

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Pressure Distribution ◽  
Small Amplitude ◽  
High Speed ◽  
Fluid Film ◽  
Distribution Model ◽  
Squeeze Film ◽  
Fluid Inertia ◽  
Inertia Effects ◽  
Squeeze Film Dampers ◽  
Reaction Forces

This work represents a pressure distribution model for finite length squeeze film dampers (SFDs) executing small amplitude circular-centered orbits (CCOs) with application in high-speed turbomachinery design. The proposed pressure distribution model only accounts for unsteady (temporal) inertia terms, since based on order of magnitude analysis, for small amplitude motions of the journal center, the effect of convective inertia is negligible relative to unsteady (temporal) inertia. In this work, the continuity equation and the momentum transport equations for incompressible lubricants are reduced by assuming that the shapes of the fluid velocity profiles are not strongly influenced by the inertia forces, obtaining an extended form of Reynolds equation for the hydrodynamic pressure distribution that accounts for fluid inertia effects. Furthermore, a numerical procedure is represented to discretize the model equations by applying finite difference approximation (FDA) and to numerically determine the pressure distribution and fluid film reaction forces in SFDs with significant accuracy. Finally, the proposed model is incorporated into a simulation model and the results are compared against existing SFD models. Based on the simulation results, the pressure distribution and fluid film reaction forces are significantly influenced by fluid inertia effects even at small and moderate Reynolds numbers.

Analysis on Segment Floating in the Construction of Large-Diameter Crossing-River Shield Tunnel

2015 ◽  
Vol 724 ◽  
pp. 17-21
Author(s):  
Run Lai Zhang ◽  
Li Ming Tang ◽  
Kun Tang
Keyword(s):  
Frictional Force ◽  
Large Diameter ◽  
Shield Tunnel ◽  
Shield Tunneling ◽  
Factors Affecting ◽  
Grouting Pressure ◽  
Rapid Setting ◽  
Grouting Material ◽  
Longitudinal Stiffness ◽  
Initial Solidification

Segment floating is a common problem met in the construction of large-diameter crossing-river shield tunnel. The factors affecting segment floating are discussed first and analyzed by numerical simulation, including the properties of grouting material, the speed of shield tunneling, grouting pressure difference, the tunnel longitudinal stiffness, frictional force between segment rings and weight of the supporting system. The simulation results indicate that segment floating will reduce by shortening slurry’s initial solidification time, slowing shielding speed, improving the tunnel longitudinal stiffness as well as increasing the frictional force between segment rings. And some measures are given such as applying new rapid-setting slurries, shear pins, rubber mats with high friction coefficient and pre-stressed bolts

scholarly journals Investigation on the Influence Caused by Shield Tunneling: WSN Monitoring and Numerical Simulation

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hao Liu ◽  
Jinjiang Shi ◽  
Jiasen Li ◽  
Chao Liu
Keyword(s):  
Signal Transmission ◽  
Monitoring Data ◽  
Shield Tunnel ◽  
Support Pressure ◽  
Shield Tunneling ◽  
Tunnel Face ◽  
Wireless Monitoring ◽  
Mems Sensor ◽  
Grouting Pressure ◽  
Transmission Test

Traditional monitoring techniques are faced with the problems of low acquisition frequency and easy to be affected by the construction environment during the shield tunneling, which cannot meet the actual needs of timeliness monitoring of surrounding environmental impact on shield tunnel construction. Based on this actual demand, a wireless sensor network (WSN) system was used to monitor the response of shield tunnel segments and surrounding buildings during the shield tunneling in this study. According to the result of the signal transmission test, an optimization scheme of microelectromechanical system (MEMS) sensor layout is designed to improve the monitoring efficiency of the WSN system. Through the comparative analysis of WSN system monitoring data and traditional monitoring data, it is found that, with the increasing distance between the monitoring section and the tunnel face, the convergence value of tunnel lining clearance gradually tends to be stable, and the wireless monitoring results of transverse clearance convergence of the tunnel in this section are consistent with the overall deformation trend of the convergence gauge monitoring results. This study also simulated the shield tunneling adjacent buildings using a nonlinear finite element method. A parameter sensitivity analysis of the support pressure of the excavation face and the grouting pressure at the tail of the shield is carried out. The results show that the surface settlement can be reduced by properly increasing the grouting pressure and the support pressure of the excavation face. Moreover, increasing the support pressure of the excavation face has a better inhibition effect on the settlement of the surface soil than increasing the grouting pressure.

scholarly journals Development of Pressure Distribution Model in Ventilation Ducts of the Brake Disc with Forced Cooling

2021 ◽  
Vol 24 (1) ◽  
pp. 19
Author(s):  
A. E. Litvinov ◽  
P. A. Polyakov ◽  
R. S. Tagiev ◽  
N. A. Zadayanchuk ◽  
A. A. Golikov ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Distribution Model ◽  
Brake Disc ◽  
Ansys Fluent ◽  
Ventilation Ducts ◽  
Forced Cooling

В процессе вращения тормозного диска в вентиляционные каналы попадает воздушный поток, который охлаждает нерабочие поверхности тормозного диска. Для увеличения интенсивности теплообмена от нагретых поверхностей нередко используются системы принудительного охлаждения. Основной задачей систем принудительного охлаждения фрикционных узлов является снижение тепловой нагруженности. Теплоотдача от нагретых поверхностей тормозного диска зависит от количества смен охлаждающего воздуха, т. е. от пропускной способности вентиляционного аппарата. Параметрами, которые влияют на пропускную способность вентиляционного аппарата, могут быть как геометрические размеры, так и аэродинамические показатели (входное давление, координаты источника подачи охлаждаемого воздуха и угол его атаки).В статье приводятся теоретические исследования в виде модели распределения давления внутри вентиляционных каналов. Согласно разработанной модели внутри вентиляционных каналов в процессе вращения тормозного диска наблюдается инверсия давления. Это оказывает влияние на наполняемость вентиляционных каналов тормозного диска воздухом, а в дальнейшем – на тепловую нагруженность всего фрикционного узла. Ребро вентиляционных каналов в разрабатываемой модели распределения давления представляется как пластина, помещенная в воздушный поток под некоторым углом атаки. С помощью расчетного метода обосновано заключение о перепаде давления по всей длине ребра перегородки вентиляционного канала. Полученное распределение давления внутри вентиляционного аппарата возможно заменить результирующей силой. В зависимости от направления действия она может быть как вспомогательной силой при торможении, так и силой сопротивления. Направление действия результирующей силы зависит от сектора установки источника принудительной подачи охлаждающего воздуха. Для подтверждения теоретического изыскания о расположении источника подачи охлаждаемого воздуха было проведено компьютерное моделирование в программном модуле ANSYS Fluent. В рамках компьютерного моделирования исследовалось влияние расположения источника потока воздуха на распределение давление внутри вентиляционных каналов тормозного диска. Полученные результаты позволяют говорить о влиянии расположения источника охлаждающего воздуха на распределение давления внутри вентиляционного аппарата тормозного диска. Это подтверждает гипотезу о том, что координаты источника воздуха и угол атаки могут являться параметрами для оптимизации при создании систем принудительного охлаждения. Помимо этого результата компьютерное моделирование в модуле ANSYS Fluent на основании CFD-модели позволило предложить точки приложения результирующих сил относительно длины вентиляционного канала в зависимости от координат расположения источника принудительной подачи воздуха.Теоретические выкладки подтверждаются как расчетным методом с подстановкой исходных данных в модель распределения, так и методом компьютерного моделирования вентилируемого тормозного диска. Результаты исследований могут дать оценку эффективности оптимизации систем принудительного охлаждения с точки зрения установки источника подачи воздуха и распределения давления в радиальных вентиляционных каналах тормозного диска.

Two-Dimensional Pore Pressure Distribution Model to Evaluate Effects of Shale Semipermeable Membrane Characteristics

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Jia Wei ◽  
Yuanfang Cheng ◽  
Chuanliang Yan
Keyword(s):  
Diffusion Coefficient ◽  
Pressure Distribution ◽  
Pore Pressure ◽  
Effective Diffusion Coefficient ◽  
Early Stage ◽  
Drilling Fluid ◽  
Effective Diffusion ◽  
Solute Diffusion ◽  
Sensitivity Analyses ◽  
Distribution Model

During the drilling of shale formations, drilling fluids can intrude into the wellbore, raise the pore pressure, and lead to wellbore instability. Based on the thermodynamic theory, a new model was established to calculate pore pressure. The model considers the effects of solute diffusion and solution convection and conducts sensitivity analyses. The results show that the drilling fluid activity significantly affects the pore pressure distribution. The pore pressure under high drilling fluid activity will increase rapidly in the early stage. Low drilling fluid activity can effectively suppress the growth of pore pressure. And a low effective diffusion coefficient of solute and a high membrane efficiency also help to reduce pore pressure. Therefore, reducing drilling fluid activity should be conducted in priority in drilling fluid design. Lowering its solute effective diffusion coefficient and increasing its viscosity can also be considered as auxiliary methods.

The Establishment of Ninety Degree Gas Elbow Pipes Internal Pressure Distribution Model

2014 ◽  
Vol 670-671 ◽  
pp. 696-699 ◽  
Author(s):  
Xiao Yang Lu ◽  
Yong Zhou ◽  
Shi Ying Chen ◽  
Xin Guang Li ◽  
Hong Liang Zhu
Keyword(s):  
Numerical Simulation ◽  
High Pressure ◽  
Internal Pressure ◽  
Pressure Distribution ◽  
High Velocity ◽  
Three Dimensional ◽  
Distribution Model ◽  
Geometrical Parameters ◽  
Maximum Relative Error ◽  
Nonlinear Fitting

According to the principle of harmonious dimensions, the qualitative distribution model of the internal pressure on elbow pipes were determined; Through FLUENT numerical simulation, the internal pressure were given under 96 kinds of gas fluid conditions; By analyzing the variation of the internal pressure with flow and geometrical parameters, the variation of the internal pressure distribution within the elbow pipes has been studied; By means of 1stOpt nonlinear fitting package, the formula of three-dimensional internal pressure distribution was determined; Compared with the numerical results, the maximum relative error is 0.012%. The formula provides theoretical bases for strength check, the transport pipeline and wall thickness design of the high pressure, high velocity elbow.

Theoretical Analysis of the Sole Plate of Semi-Rigid Light Steel Column Footings on the Basis of Winkler Model of Elastic Foundation Beam

2013 ◽  
Vol 660 ◽  
pp. 105-110 ◽  
Author(s):  
Xiao Li ◽  
Min Ding ◽  
Xiu Gen Jiang
Keyword(s):  
Pressure Distribution ◽  
Elastic Foundation ◽  
Theoretical Solution ◽  
Distribution Model ◽  
Eccentric Load ◽  
Concentrated Load ◽  
Winkler Model ◽  
Steel Column ◽  
Elastic Foundation Beam ◽  
Linear Pressure Distribution

To obtain the pressure distribution model on the sole plate of semi-rigid light steel column footing, the deflection formulas of beams with free ends on elastic foundation subjected to arbitrarily concentrated load and arbitrarily trapezoidal load were developed by applying the Winkler model of elastic foundation beam and initiate-parameter expressions of deformation and internal force by presetting boundary condition and calculating with Maple software. The sole plate of semi-rigid square steel tube column footing was converted into elastic foundation beam which is supported by concrete foundation, the mechanical model of the sole plate subjected to eccentric load was obtained, and the theoretical solution of pressure distribution on the sole plate was presented. Then the theoretical solution was compared with the numerical solution via an example. The results show that the two solutions meet well with each other, and there is much great difference between the pressure distribution on sole plate of semi-rigid light steel column footing and the linear pressure distribution model in common use. As a result, the semi-rigid column footing stiffness would be overestimated by using linear pressure distribution model. The fruits presented in this paper are useful and convenient to the design of semi-rigid light steel column footing.

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