Test of Solidification Characteristics of Grouting and the Effect on Strata Deformation in Shield Tunnelling

2012 ◽  
Vol 568 ◽  
pp. 80-84
Author(s):  
Xiao Chun Zhong ◽  
Wei Ke Qin ◽  
Hai Wang
Keyword(s):  
Numerical Model ◽  
Rigid Body ◽  
Active Control ◽  
Calculation Method ◽  
Civil Engineering ◽  
Test Results ◽  
Shield Tunneling ◽  
Shield Tunnelling ◽  
Strata Deformation ◽  
Over Time

Back-fill Grouting is a key procedure for the active control of strata settlement during shield tunnelling in civil engineering. The paper studies the stress - strain characteristics of grouting and the state of grout, which changes from liquid to solid over time and is simulated by variable rigid body. The model of flowing state are divided in four phases from liquid-plastic to rigid state. The paper establish a numerical model of shield tunnelling in civil engineering with the consideration of characteristics of grout deformation, and has analyzed law of strata settlement. The test results show that the calculation method can well accord with the four stages of strata deformation, and can more accurately reflect the process of strata deformation caused by shield tunneling.

Prestressed Time-Limited Aging Analyses of Concrete Containment Structure

2017 ◽  
Author(s):  
Dahua Cai ◽  
Yonghuan Wang ◽  
Jiangtao Zhang ◽  
Lin Yang ◽  
Hua Rong ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Finite Element Model ◽  
Prestressed Concrete ◽  
Element Model ◽  
Test Results ◽  
Prestress Loss ◽  
Pressure Test ◽  
Key Factor ◽  
Over Time

For prestressed concrete containment structure, prestress loss is a key factor that affects the performance of containment structure. Therefore, prestressed time-limited aging analysis (TLAA) is essential for containment structures. The main objective of prestressed TLAA is to assess the safety of containment structures after prestress loss occurred over time. This paper takes the in-service containment structure as an example to investigate the method of TLAA for grounted prestressed containment structure. Firstly, it introduces methods for prestressed TLAA. Secondly, a finite element model of containment structure is established to calculate the minimum required value (MRV) of prestress. The numerical model is verified by the pressure test results. Thirdly, prestress loss of tendons is calculated. Finally, the residual prestress of tendons are compared with the MRV of prestress to confirm whether the containment can service in a certain period. This study can provide guidance for goouted prestressed TLAA of containment structures.

Active Control of Elastic and Rigid Body Response of a Three Dimensional Underwater Structure

1995 ◽  
Vol 117 (1) ◽  
pp. 30-37 ◽  
Author(s):  
H. Suzuki ◽  
K. Yoshida ◽  
K. Watanabe
Keyword(s):  
Numerical Model ◽  
Rigid Body ◽  
Active Control ◽  
Structural Model ◽  
Scale Up ◽  
Three Dimensional ◽  
Basic Research ◽  
Weather Conditions ◽  
Body Motion ◽  
Elastic Response

One key technology for the offshore development of the increasing water depth will be remotely operated installation and construction of flexible structure in the deep water or on the seabed. The flexibility comes from scale-up or weight reduction of the structure. Conventional operation from the sea surface is affected by the weather conditions, and, therefore, not so efficient. This paper presents basic research on active control of elastic response and rigid body motion of an underwater elastic structure toward the remotely operated installation technique. The numerical model of the dynamics of the structural model is formulated, and based on the numerical model the control is formulated. The formulated control is tested by computer simulations and model experiments. The structural model is propelled by thrusters and taken from initial position to another position, while the elastic responses are controlled by variable buoyancy-type actuators.

Text Analysis on Punishment Clauses in Korean Law: Changes in the Number, Level, and Balance of Punishment Clauses Over 30 Years

2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Jaeyoon Kim
Keyword(s):  
Text Analysis ◽  
Civil Engineering ◽  
Sex Offenses ◽  
Web Crawler ◽  
Comprehensive Review ◽  
Low Level ◽  
Legal Code ◽  
Changes Over Time ◽  
Over Time

Abstract For this study, I completed a comprehensive review of punishment clauses in the Korean Legal Code from 1985 to 2016. Using a web crawler and text analysis, I gathered data on the laws and then identified the content of the penal sentence in each clause. By investigating the data, I was able to quantify and assess changes over time in: (1) the number of punishment clauses; (2) the severity of sentences; and (3) the balance between imprisonment and fines. In order to examine the causes of these changes, I separated the data into different sentence levels and sectors. I found that low-level punishment clauses had grown quickly, and some of the sectors responsible for the change included civil engineering and sex offenses. This comprehensive review of the penal sentences revealed issues of concern related to overcriminalization, overpenalization, and an imbalance of punishment level in the Korean Legal Code.

scholarly journals Influence of Hydrogeochemistry on Tunnel Drainage in Evaporitic Formations: El Regajal Tunnel Case Study (Aranjuez, Spain)

2021 ◽  
Vol 13 (3) ◽  
pp. 1505
Author(s):  
Ignacio Menéndez Pidal ◽  
Jose Antonio Mancebo Piqueras ◽  
Eugenio Sanz Pérez ◽  
Clemente Sáenz Sanz
Keyword(s):  
High Speed ◽  
Civil Engineering ◽  
Saturation Index ◽  
The Subject ◽  
Under Construction ◽  
Underground Flow ◽  
Very High ◽  
Over Time

Many of the large number of underground works constructed or under construction in recent years are in unfavorable terrains facing unusual situations and construction conditions. This is the case of the subject under study in this paper: a tunnel excavated in evaporitic rocks that experienced significant karstification problems very quickly over time. As a result of this situation, the causes that may underlie this rapid karstification are investigated and a novel methodology is presented in civil engineering where the use of saturation indices for the different mineral specimens present has been crucial. The drainage of the rock massif of El Regajal (Madrid-Toledo, Spain, in the Madrid-Valencia high-speed train line) was studied and permitted the in-situ study of the hydrogeochemical evolution of water flow in the Miocene evaporitic materials of the Tajo Basin as a full-scale testing laboratory, that are conforms as a whole, a single aquifer. The work provides a novel methodology based on the calculation of activities through the hydrogeochemical study of water samples in different piezometers, estimating the saturation index of different saline materials and the dissolution capacity of the brine, which is surprisingly very high despite the high electrical conductivity. The circulating brine appears unsaturated with respect to thenardite, mirabilite, epsomite, glauberite, and halite. The alteration of the underground flow and the consequent renewal of the water of the aquifer by the infiltration water of rain and irrigation is the cause of the hydrogeochemical imbalance and the modification of the characteristics of the massif. These modifications include very important loss of material by dissolution, altering the resistance of the terrain and the increase of the porosity. Simultaneously, different expansive and recrystallization processes that decrease the porosity of the massif were identified in the present work. The hydrogeochemical study allows the evolution of these phenomena to be followed over time, and this, in turn, may facilitate the implementation of preventive works in civil engineering.

Experimental Research on the Engineering Properties of Foam-Improved Red Clay Soil

2011 ◽  
Vol 261-263 ◽  
pp. 1831-1835
Author(s):  
Guo Gang Qiao ◽  
Da Jun Yuan ◽  
Bo Liu
Keyword(s):  
Experimental Research ◽  
Clay Soil ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Screw Conveyor ◽  
Test Results ◽  
X Ray Diffraction ◽  
Shield Tunneling ◽  
Red Clay ◽  
Improvement Measures

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.

The New Measurement and Calculation Method for Dynamic Parameters of DC Motor Based on dSPACE System

2012 ◽  
Vol 562-564 ◽  
pp. 1496-1500
Author(s):  
Qiang Li ◽  
Wei Chen ◽  
Ren He
Keyword(s):  
Mathematical Model ◽  
Duty Cycle ◽  
Calculation Method ◽  
Dc Motor ◽  
Control Algorithms ◽  
Dynamic Parameters ◽  
Hardware In The Loop ◽  
Test Results ◽  
Complex Control ◽  
Measurement And Calculation Method

To investigate the accuracy of modeling DC motor, the platform for measurement and calculation dynamic parameters is built by the Hardware-In-the-Loop(HIL) method based on dSPACE system. The running state of DC motor has to be changed with adjustment of PWM duty-cycle using ControlDesk software. Having got measurement and calculation parameters value of DC motor, we compare the test results with simulation value using the model of DC motor with cascade control in Matlab/Simulink software according to the classical mathematical model. It confirms the established model of DC motor accurately and reliability using new parameters, which provides the basis of more complex control algorithms and also indicates that the feasibility and generalization application value of measurement and calculation method for DC motor.

Methodology Development for Simulating Full Frontal and Offset Frontal Impacts Using Full Vehicle MADYMO Models

1999 ◽  
Author(s):  
Bala Deshpande ◽  
Gunasekar TJ ◽  
Russell Morris ◽  
Sudhanshu Parida ◽  
Mostafa Rashidy ◽  
...  
Keyword(s):  
Rigid Body ◽  
Joint Stiffness ◽  
Side Impact ◽  
Computational Time ◽  
Test Results ◽  
Vehicle Interior ◽  
Significant Saving ◽  
Methodology Development ◽  
Full Vehicle ◽  
Frontal Impacts

Abstract MADYMO articulated full vehicle models of the 1992 Ford Taurus, 1995 Chevrolet Lumina and the 1994 Dodge Intrepid for frontal and side impact modes have been developed and validated against test data. MADYMO (Mathematical Dynamic Model) is typically used to model occupants in the environment of the vehicle interior and thus finds application mainly in assessing occupant injuries. In this study however, MADYMO has been employed not only to model the occupants but also to represent the major load bearing structures in the vehicles. Input for the MADYMO models consisting of rigid body joint stiffness was obtained from corresponding full vehicle Finite Element (FE) models. Model validation was done by comparing the vehicle and dummy numbers with the New Car Assessment Program (NCAP) test results. Models correlated very well with both test and FE data. This modeling approach demonstrates the utility of rigid body based full car models for crashworthiness analysis. Such models result in significant saving in computational time and resources. In this paper, we describe the simulation of two different crash modes: full frontal and offset frontal impacts using the full vehicle MADYMO models. These simulations were validated with the corresponding test results in full frontal mode and IIHS offset mode. The models are useful for simulating a variety of impact situations, for example, with different occupant sizes, occupant positions, impact velocities, and in car to car impacts for performing compatibility studies.

Compliant Pantographs via the Pseudo-Rigid-Body Model

1998 ◽  
Author(s):  
Andrew J. Nielson ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Test Results ◽  
Rigid Link ◽  
Body Model ◽  
Design Flexibility ◽  
Model Predictions ◽  
Rigid Body Model ◽  
Classical Mechanism

Abstract This paper uses a familiar classical mechanism, the pantograph, to demonstrate the utility of the pseudo-rigid-body model in the design of compliant mechanisms to replace rigid-link mechanisms, and to illustrate the advantages and limitations of the resulting compliant mechanisms. To demonstrate the increase in design flexibility, three different compliant mechanism configurations were developed for a single corresponding rigid-link mechanism. The rigid-link pantograph consisted of six links and seven joints, while the corresponding compliant mechanisms had no more than two links and three joints (a reduction of at least four links and four joints). A fourth compliant pantograph, corresponding to a rhomboid pantograph, was also designed and tested. The test results showed that the pseudo-rigid-body model predictions were accurate over a large range, and the mechanisms had displacement characteristics of rigid-link mechanisms in that range. The limitations of the compliant mechanisms included reduced range compared to their rigid-link counterparts. Also, the force-deflection characteristics were predicted by the pseudo-rigid-body model, but they did not resemble those for a rigid-link pantograph because of the energy storage in the flexible segments.

Numerical calculation of crack width in prestressed concrete beams with bond-slip effect

2019 ◽  
Vol 15 (2) ◽  
pp. 523-536
Author(s):  
Jinliang Liu ◽  
Yanmin Jia ◽  
Guanhua Zhang ◽  
Jiawei Wang
Keyword(s):  
Numerical Calculation ◽  
Numerical Model ◽  
Prestressed Concrete ◽  
Calculation Method ◽  
Crack Width ◽  
Calculation Model ◽  
Content Type ◽  
Bond Slip ◽  
Stress Calculation ◽  
Bonding Performance

Purpose The calculation of the crack width is necessary for the design of prestressed concrete (PC) members. The purpose of this paper is to develop a numerical model based on the bond-slip theory to calculate the crack width in PC beams. Design/methodology/approach Stress calculation method for common reinforcement after beam crack has occurred depends on the difference in the bonding performance between prestressed reinforcement and common reinforcement. A numerical calculation model for determining the crack width in PC beams is developed based on the bond-slip theory, and verified using experimental data. The calculation values obtained by the proposed numerical model and code formulas are compared, and the applicability of the numerical model is evaluated. Findings The theoretical analysis and experimental results verified that the crack width of PC members calculated based on the bond-slip theory in this study is reasonable. Furthermore, the stress calculation method for the common reinforcement is verified. Compared with the model calculation results obtained in this study, the results obtained from code formulas are more conservative. Originality/value The numerical calculation model for crack width proposed in this study can be used by engineers as a reference for calculating the crack width in PC beams to ensure the durability of the PC member.

scholarly journals No Sustained Attention Differences in a Longitudinal Randomized Trial Comparing Mindfulness Based Stress Reduction versus Active Control

2019 ◽  
Author(s):  
Donal G. MacCoon ◽  
Katherine A. MacLean ◽  
Richard J Davidson ◽  
Clifford Saron ◽  
Antoine Lutz
Keyword(s):  
Active Control ◽  
Sustained Attention ◽  
Stress Reduction ◽  
Visual Discrimination ◽  
Longitudinal Design ◽  
Mindfulness Practice ◽  
Clinical Population ◽  
Future Research ◽  
Mindfulness Based Stress Reduction ◽  
Over Time

Background: Mindfulness Based Stress Reduction (MBSR) is a secular form of meditation training. The vast majority of the extant literature investigating the health effects of mindfulness interventions relies on wait-list control comparisons. Previous studies have found that meditation training over several months is associated with improvements in cognitive control and attention.Methodology/Principal Findings: We used a visual continuous performance task (CPT) to test the effects of eight weeks of mindfulness training on sustained attention by comparing MBSR to the Health Enhancement Program (HEP), a structurally equivalent, active control condition in a randomized, longitudinal design (ClinicalTrials.gov, NCT01301105) focusing on a non-clinical population typical of MBSR participants. Researchers were blind to group assignment. 63 community participants were randomized to either MBSR (n = 31) or HEP (n = 32). CPT analyses were conducted on 29 MBSR participants and 25 HEP participants. We predicted that MBSR would improve visual discrimination ability and sustained attention over time on the CPT compared to HEP, with more home practice associated with greater improvements. Our hypotheses were not confirmed but we did find some evidence for improved visual discrimination similar to effects in partial replication of other research. Our study had sufficient power to demonstrate that intervention groups do not differ in their improvement over time in sustained attention performance. One of our primary predictions concerning the effects of intervention on attentional fatigue was significant but not interpretable.Conclusions: Attentional sensitivity is not affected by mindfulness practice as taught in MBSR, but it is unclear whether mindfulness might positively affect another aspect of attention, vigilance. These results also highlight the relevant procedural modifications required by future research to correctly investigate the role of sustained attention in similar samples.

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