scholarly journals Risk Assessment System Based on Fuzzy Composite Evaluation and a Backpropagation Neural Network for a Shield Tunnel Crossing under a River

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xiao Liang ◽  
Taiyue Qi ◽  
Zhiyi Jin ◽  
Shaojie Qin ◽  
Pengtao Chen
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Risk Assessment ◽  
Assessment System ◽  
Chamber Pressure ◽  
Shield Tunnel ◽  
Risk Level ◽  
Backpropagation Neural Network ◽  
Grouting Pressure ◽  
Simulation Results

Constructing a shield tunnel that crosses under a river poses considerable safety risks, and risk assessment is essential for guaranteeing the safety of tunnel construction. This paper studies a risk assessment system for a shield tunnel crossing under a river. Risk identification is performed for the shield tunnel, and the risk factors and indicators are determined. The relationship between the two is determined preliminarily by numerical simulation, the numerical simulation results are verified by field measurements, and a sample set is established based on the numerical simulation results. Fuzzy comprehensive evaluation and a backpropagation neural network are then used to evaluate and analyze the risk level. Finally, the risk assessment system is used to evaluate the risk for Line 5 of the Hangzhou Metro in China. Based on the evaluation results, adjustments to the slurry strength, grouting pressure, and soil chamber pressure are proposed, and the risk is mitigated effectively.

scholarly journals Numerical Simulation of EPB Shield Tunnelling with TBM Operational Condition Control Using Coupled DEM–FDM

2021 ◽  
Vol 11 (6) ◽  
pp. 2551
Author(s):  
Hyobum Lee ◽  
Hangseok Choi ◽  
Soon-Wook Choi ◽  
Soo-Ho Chang ◽  
Tae-Ho Kang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Large Scale ◽  
Tunnel Boring Machine ◽  
Chamber Pressure ◽  
Screw Conveyor ◽  
Shield Tunnel ◽  
Pressure Balance ◽  
Operational Conditions ◽  
Shield Tunnelling ◽  
Epb Shield

This study demonstrates a three-dimensional numerical simulation of earth pressure balance (EPB) shield tunnelling using a coupled discrete element method (DEM) and a finite difference method (FDM). The analysis adopted the actual size of a spoke-type EPB shield tunnel boring machine (TBM) consisting of a cutter head with cutting tools, working chamber, screw conveyor, and shield. For the coupled model to reproduce the in situ ground condition, the ground formation was generated partially using the DEM (for the limited domain influenced by excavation), with the rest of the domain being composed of FDM grids. In the DEM domain, contact parameters of particles were calibrated via a series of large-scale triaxial test analyses. The model simulated tunnelling as the TBM operational conditions were controlled. The penetration rate and the rotational speed of the screw conveyor were automatically adjusted as the TBM advanced to prevent the generation of excessive or insufficient torque, thrust force, or chamber pressure. Accordingly, these parameters were maintained consistently around their set operational ranges during excavation. The simulation results show that the proposed numerical model based on DEM–FDM coupling could reasonably simulate EPB driving while considering the TBM operational conditions.

scholarly journals An Approach to Risk Assessment and Threat Prediction for Complex Object Security Based on a Predicative Self-Configuring Neural System

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 102
Author(s):  
Nikolai Vladimirovich Korneev ◽  
Julia Vasilievna Korneeva ◽  
Stasis Petrasovich Yurkevichyus ◽  
Gennady Ivanovich Bakhturin
Keyword(s):  
Neural Network ◽  
Risk Assessment ◽  
Fundamental Problem ◽  
Experimental Studies ◽  
Neural System ◽  
Assessment System ◽  
Classification Model ◽  
Complex Object ◽  
Assessment Problems ◽  
First Time

We identified a set of methods for solving risk assessment problems by forecasting an incident of complex object security based on incident monitoring. The solving problem approach includes the following steps: building and training a classification model using the C4.5 algorithm, a decision tree creation, risk assessment system development, and incident prediction. The last system is a predicative self-configuring neural system that includes a SCNN (self-configuring neural network), an RNN (recurrent neural network), and a predicative model that allows for determining the risk and forecasting the probability of an incident for an object. We proposed and developed: a mathematical model of a neural system; a SCNN architecture, where, for the first time, the fundamental problem of teaching a perceptron SCNN was solved without a teacher by adapting thresholds of activation functions of RNN neurons and a special learning algorithm; and a predicative model that includes a fuzzy output system with a membership function of current incidents of the considered object, which belongs to three fuzzy sets, namely “low risk”, “medium risk”, and “high risk”. For the first time, we gave the definition of the base class of an object’s prediction and SCNN, and the fundamental problem of teaching a perceptron SCNN was solved without a teacher. We propose an approach to neural system implementation for multiple incidents of complex object security. The results of experimental studies of the forecasting error at the level of 2.41% were obtained.

scholarly journals Experimental Research and Numerical Simulation on Grouting Quality of Shield Tunnel Based on Impact Echo Method

2016 ◽  
Vol 2016 ◽  
pp. 1-10
Author(s):  
Fei Yao ◽  
Guangyu Chen ◽  
Jianhong Su
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Working Conditions ◽  
Acoustic Impedance ◽  
Shield Tunnel ◽  
Test Results ◽  
Impact Echo ◽  
Simulation Results ◽  
The Impact ◽  
Impact Echo Method

To identify shield grouting quality based on impact echo method, an impact echo test of segment-grouting (SG) test piece was carried out to explore effect of acoustic impedance of grouting layers and grouting defects on impact echo law. A finite element numerical simulation on the impact echo process was implemented. Test results and simulation results were compared. Results demonstrated that, under some working conditions, finite element simulation results and test results both agree with theoretical values. The acoustic impedance ratio of SG material influenced the echo characteristics significantly. But thickness frequency could not be detected under some working conditions because the reflected energy is weak. Frequency feature under grouting defects was more complicated than that under no grouting defects.

A neural network approach for retailer risk assessment in the aftermarket industry

2019 ◽  
Vol 26 (5) ◽  
pp. 1631-1647 ◽  
Author(s):  
Shirin Rezaei ◽  
Sajjad Shokouhyar ◽  
Mostafa Zandieh
Keyword(s):  
Neural Network ◽  
Risk Assessment ◽  
Supply Chain ◽  
Mitigation Strategies ◽  
Risk Level ◽  
Self Organizing Map ◽  
Neural Network Approach ◽  
Content Type ◽  
Risk Levels ◽  
Risk Management Process

Purpose Given the competitive environment and complicated relationships in supply chains in the modern era, it is important to take into account internal and external risks. In addition, proper methods must be designed to evaluate these risks correctly. The purpose of this paper is to provide a suitable map based on the artificial neural network technique to assess and classify the risk levels of retailers who have interconnected rules in the downstream of the supply chain. Design/methodology/approach In this research, a model for risk assessment with a hexagonal grid and 2D self-organizing map was applied. Findings According to the results, the model used in the study can provide a basis for classification of retailers based on the specified risk levels defined by the experts and risk managers of the company. Also with the model’s visual output, managers can have a better understanding of the distribution of the risk level of retailers. Practical implications The proposed methodology can be adopted by managers to assess the risk of members involved in the supply chain, helping them to formulate the risk mitigation strategies based on the risk levels. Originality/value As a part of the risk management process, organizations can use this developed method to reduce the existing risks imposed by the members or customers on the company.

Analysis of Anti-Floating Measures and Construction Parameters of Shield Tunnel through River under Ultra-Shallow Covering

2013 ◽  
Vol 353-356 ◽  
pp. 628-634
Author(s):  
Xiao Long Li ◽  
Bing Long Wang ◽  
Xue Li ◽  
Chang Ji
Keyword(s):  
Construction Safety ◽  
Chamber Pressure ◽  
Shield Tunnel ◽  
Floating Plate ◽  
Surface Uplift ◽  
Grouting Pressure ◽  
Driving Speed ◽  
Jet Grouting ◽  
Uplift Pile

Shield tunnel through the river under shallow covering usually facing the phenomenon of tunnel floating due to the thickness of overburden layer inadequate,and resulting in flooding accident due to the overburden layer split.Aiming at the project of Hangzhou metro line one through the Tangjia river under ultra-shallow covering,checking the thickness of overburden layer and taking the measures of anti-floating plate,uplift pile and jet-grouting piles to resist tunnel floating;through the control of soil chamber pressure,driving speed and grouting pressure in the process of construction,tunnel axis is controlled within±30mm,the amount of surface uplift is less than 10mm,tunnel segments without breakage and leakage.The results show that using anti-floating plate,uplift pile and jet-grouting piles,and controlling the construction parameters strictly are effective measures to resist tunnel floating and ensure construction safety.

scholarly journals Subway Tunnel Construction Settlement Analysis Based on the Combination of Numerical Simulation and Neural Network

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qiangqiang Ma ◽  
Wentao Li ◽  
Yongjun Zhang
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Risk Assessment ◽  
Traffic Congestion ◽  
Urban Traffic ◽  
City Size ◽  
Tunnel Construction ◽  
Subway Tunnel ◽  
Settlement Analysis

Under the background of rapid economic development and the continuous expansion of city size, people’s travel is deeply troubled by the problem of urban traffic congestion. Subway is an effective way to relieve traffic pressure and plays an important role in its use. In the process of building the city subway, the excavation of the underground tunnel is the most critical. However, the excavation of the tunnel will inevitably disturb the nearby soil, change the stratum stress conditions, and make the stress distribution uneven. If the surface settlement is too large, it will not only affect the normal construction of the tunnel but also cause damage to the surrounding buildings (structures), roads, underground pipelines, and so on, resulting in very serious malignant consequences. In this study, Cuobuling Station is taken as a case study. First, the construction status of the subway tunnel in the station is analyzed, and then the monitoring results are analyzed. According to the cross-section settlement law, the numerical simulation and neural network are used to build a model, calculate the numerical simulation results, and carry out a risk assessment of regression model. Finally, combined with the tunnel construction situation of the station, according to the risk assessment results, the concrete measures are put forward to deal with the subway tunnel construction settlement problem.

scholarly journals An Integrated Method for Fire Risk Assessment in Residential Buildings

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Hongfu Mi ◽  
Yaling Liu ◽  
Wenhe Wang ◽  
Guoqing Xiao
Keyword(s):  
Risk Assessment ◽  
Residential Buildings ◽  
Residential Building ◽  
Fire Risk ◽  
Assessment System ◽  
Risk Level ◽  
Mathematical Framework ◽  
Building Fires ◽  
Building Fire ◽  
Fire Risk Assessment

Building fires are characterized by high uncertainty, so their fire risk assessment is a very challenging task. Many indexes and parameters related to building fires are ambiguous and uncertain; as a result, a flexible and robust method is needed to process quantitative or qualitative data and update existing information when new data are available. This paper presents a novel model to deal with the uncertainty of the residential building fire risk and systematically optimize its performance effectiveness. The model includes fuzzy theory, evidence reasoning theory, and expected utility methods. Fuzzy analysis hierarchy process is applied to analyze the residential building fire risk index system and determine the weights of the risk indexes, while the evidence reasoning operator is used to synthesize them. Three buildings were selected as a case study to illustrate the proposed fire risk model. The results show that the fire risk level of three buildings corresponds to “moderate” or below which is consistent with the previous study. These results also truly reflect the actual situation of fire safety in these residential buildings. The application of this model provides a powerful mathematical framework for cooperative modeling of the fire risk assessment system and allows data to be analyzed step by step in a systematic manner. It is expected that the proposed model could provide managers and researchers with flexible and transparent tools to effectively reduce the fire risk in the system.

Research on Deformation Influence of Shield Undercrossing the Existing Metro Double Shield Tunnel

2014 ◽  
Vol 1065-1069 ◽  
pp. 378-382 ◽  
Author(s):  
Hua Peng ◽  
Zhi Yong Dong ◽  
Yun Liang Liu
Keyword(s):  
Numerical Simulation ◽  
Model Calculation ◽  
Water Transfer ◽  
Control Measures ◽  
Shield Tunnel ◽  
Protective Measures ◽  
Deformation Law ◽  
North Water ◽  
Simulation Results ◽  
Metro Project

In the big cities, the shield undercrossing metro project has become critical to the safety of the metro, this paper takes the South-North Water Transfer Project shield under traverse Beijing certain subway project for construction background. It makes technical schemes comparison, analyses the deformation law of the existing subway structure and propoes protective measures to prevent the existing subway structure. The analysis showed the following conclusions: in shield undercrossing the metro project, in order to reduce disturbance on surrounding soils and the existing metro structure, we should take the necessary control measures such as grouting and determine the optimum shield parameters; the overall trend of the monitoring results accords well with numerical simulation results; The reason why the actual values and model calculation values has certain deviation is that it is difficult to consider shield parameters such as the pressure of shield thrust, pressures of grouting and so on in numerical simulation.

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