Matrix transfer method of the curved-wall type tunnel lining structure calculation

2014 ◽  
pp. 707-712
Keyword(s):  
Structure Calculation ◽  
Tunnel Lining ◽  
Lining Structure ◽  
Transfer Method ◽  
Matrix Transfer Method

A Rapid Approach for Calculating the Damped Eigenvalues of a Gas Turbine on a Minicomputer: Theory

1984 ◽  
Vol 106 (2) ◽  
pp. 239-249 ◽  
Author(s):  
E. J. Gunter ◽  
R. R. Humphris ◽  
H. Springer
Keyword(s):  
Gas Turbine ◽  
Characteristic Polynomial ◽  
Normal Modes ◽  
Complex Matrix ◽  
Large Computer ◽  
Mainframe Computer ◽  
The Matrix ◽  
Rigid Body Modes ◽  
Transfer Method ◽  
Matrix Transfer Method

The calculation of the damped eigenvalues of a large multistation gas turbine by the complex matrix transfer procedure may encounter numerical difficulties, even on a large computer due to numerical round-off errors. In this paper, a procedure is presented in which the damped eigenvalues may be rapidly and accurately calculated on a minicomputer with accuracy which rivals that of a mainframe computer using the matrix transfer method. The method presented in this paper is based upon the use of constrained normal modes plus the rigid body modes in order to generate the characteristic polynomial of the system. The constrained undamped modes, using the matrix transfer process with scaling, may be very accurately calculated for a multistation turbine on a minicomputer. In this paper, a five station rotor is evaluated to demonstrate the procedure. A method is presented in which the characteristic polynomial may be automatically generated by Leverrier’s algorithm. The characteristic polynomial may be directly solved or the coefficients of the polynomial may be examined by the Routh criteria to determine stability. The method is accurate and easy to implement on a 16 bit minicomputer.

scholarly journals Analytical analyses of the effect of filled karst cavern on tunnel lining structure under complex geological conditions

AIP Advances ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 035148
Author(s):  
Jianbing Lv ◽  
Xulong Li ◽  
Yiwu He ◽  
Helin Fu ◽  
Yingmei Yin
Keyword(s):  
Tunnel Lining ◽  
Geological Conditions ◽  
Lining Structure ◽  
Karst Cavern

scholarly journals Synthesis of numerical methods for the design of segmental tunnel lining

2019 ◽  
Vol 295 ◽  
pp. 03008
Author(s):  
Rim Trad ◽  
Hussein Mroueh ◽  
Hanbing Bian ◽  
Fabrice Cormery
Keyword(s):  
Numerical Study ◽  
Direct Method ◽  
Bending Moment ◽  
Experimental Methods ◽  
Tunnel Lining ◽  
Practical Case ◽  
Lining Structure ◽  
Water Conveyance ◽  
Internal Forces ◽  
Water Conveyance Tunnel

This paper presents a numerical study that aims to compare the behavior of the segmental tunnel lining using the direct, indirect and experimental methods. This model is based on a practical case applied in university of Tongji: a project of water conveyance tunnel. A reduction in the bending moment and increasing of the displacement in the tunnel lining is showed in numerical results, when taking into account the effect of the joints. It has been shown that the number of joints in the tunnel-lining structure highly affects the results in terms internal forces and displacements. Furthermore, the internal forces obtained by the continuous method are high compared to the other methods when the effects on segmental joints on tunnel lining behaviour are usually considered. Additionally, the bending moment of the direct method with behaviour of rotation spring linear and experimental method is comparable.

scholarly journals Intelligent Classification Method for Tunnel Lining Cracks Based on PFC-BP Neural Network

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hao Ding ◽  
Xinghong Jiang ◽  
Ke Li ◽  
Hongyan Guo ◽  
Wenfeng Li
Keyword(s):  
Neural Network ◽  
Bp Neural Network ◽  
Structural Parameters ◽  
Crack Depth ◽  
Tunnel Lining ◽  
Parameter Analysis ◽  
Training Data ◽  
Concrete Lining ◽  
Common Disease ◽  
Lining Structure

Tunnel lining crack is the most common disease and also the manifestation of other diseases, which widely exists in plain concrete lining structure. Proper evaluation and classification of engineering conditions directly relate to operation safety. Particle flow code (PFC) calculation software is applied in this study, and the simulation reliability is verified by using the laboratory axial compression test and 1 : 10 model experiment to calibrate the calculation parameters. Parameter analysis is carried out focusing on the load parameters, structural parameters, dimension, and direction which affect the crack diseases. Based on that, an evaluation index system represented by tunnel buried depth (H), crack position (P), crack length (L), crack width (W), crack depth (D), and crack direction (A) is put forward. The training data of the back propagation (BP) neural network which takes load-bearing safety and crack stability as the evaluation criteria are obtained. An expert system is introduced into the BP neural network for correction of prediction results, realizing classified dynamic optimization of complex engineering conditions. The results of this study can be used to judge the safety state of cracked lining structure and provide guidance to the prevention and control of crack diseases, which is significant to ensure the safety of tunnel operation.

scholarly journals Impact Pseudostatic Load Equivalent Model and the Maximum Internal Force Solution for Underground Structure of Tunnel Lining

2016 ◽  
Vol 2016 ◽  
pp. 1-16
Author(s):  
Xuan Guo ◽  
Xiao Xin Zhang
Keyword(s):  
Model Test ◽  
Internal Force ◽  
Measured Data ◽  
Tunnel Lining ◽  
Theoretical Solution ◽  
Equivalent Model ◽  
Theoretical Formula ◽  
Circular Tunnel ◽  
Lining Structure ◽  
Force Calculation

The theoretical formula of the maximum internal forces for circular tunnel lining structure under impact loads of the underground is deduced in this paper. The internal force calculation formula under different equivalent forms of impact pseudostatic loads is obtained. Furthermore, by comparing the theoretical solution with the measured data of the top blasting model test of circular formula under different equivalent forms of impact pseudostatic loads are obtained. Furthermore, by comparing the theoretical solution with the measured data of the top blasting model test of circular tunnel, it is found that the proposed theoretical results accord with the experimental values well. The corresponding equivalent impact pseudostatic triangular load is the most realistic pattern of all test equivalent forms. The equivalent impact pseudostatic load model and maximum solution of the internal force for tunnel lining structure are partially verified.

Effect of Time-Varying on Shield Tunnel Lining Structure

2014 ◽  
Vol 580-583 ◽  
pp. 987-990
Author(s):  
Feng Jun Liu ◽  
Jun Fang Chen
Keyword(s):  
Design Theory ◽  
Aging Effect ◽  
Tunnel Lining ◽  
Shield Tunnel ◽  
Time Varying ◽  
Bending Rigidity ◽  
Concrete Shrinkage ◽  
Lining Structure ◽  
Long Time ◽  
Internal Forces

In order to survey the time-varying effect on shield tunnel lining structure, rigidity reduce in the Homogeneous Ring Design Theory is introduced. There are three methods to evaluate the rigidity reduction caused by the aging effect. The first is the bending rigidity analysis method, which considers that the bending rigidity changes with the time-dependent stress and strain. The second is the method named the equivalent moment of inertia; the last is aging coefficient method. With the Homogeneous Ring Design Theory, the internal forces and displacement of the shield tunnel segment lining can be calculated. Based on the preliminary results, using the 1st method, the reduced rigidity and the long-time displacement at different instants of time can be calculated. It is found that the concrete shrinkage and creep effect can’t be ignored in the segment design. The survey is beneficial to monitor the deformation of tunnel lining, and the maintenance of the segments. It will make the tunnel work steadily and safely during the using period.

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