scholarly journals Study on the Applicability of Dynamic Stability Evaluation Criteria by Comparison of Trackside Measurement Results of Different Track Structures

2020 ◽  
Vol 10 (22) ◽  
pp. 8245
Author(s):  
Kyuhwan Oh ◽  
Jaeik Lee ◽  
Junhyeok Choi ◽  
Yonggul Park
Keyword(s):  
Dynamic Stability ◽  
Evaluation Method ◽  
Evaluation Criteria ◽  
Railway Track ◽  
Stability Evaluation ◽  
Design Specification ◽  
Wheel Load ◽  
Field Instrumentation ◽  
Load Fluctuation ◽  
Concrete Type

Countries such as Korea adopt design codes, evaluation criteria and specifications from standards originating abroad; this leads to a lack of distinction of the separate applications of dynamic stability evaluation parameters between various track structures of different track moduli. This paper discusses the applicability of the dynamic stability evaluation method of railway track structures by assessing 10 different types of railway track sections of a newly constructed railway operation line (5 ballasted and 5 concrete type track structures) by field instrumentation testing. Parameters of track support stiffness (TSS), wheel load fluctuation, derailment coefficient, and rail displacement are measured. The respective results are first compared to the standard criteria (design specification) and comparisons between the different track types are presented as ratios. Findings show that while all of the tracks satisfy the design specification requirements, each track type measurement result varies by a noticeable degree, particularly when comparing between concrete and ballast type track structures. Results of the study demonstrate that using the same dynamic stability evaluation criteria can lead to an incorrect assessment of the track performance evaluation of track structure, and a separate evaluation parameter for ballasted and concrete track structures is required.

scholarly journals Track Modulus Assessment of Engineered Interspersed Concrete Sleepers in Ballasted Track

2020 ◽  
Vol 11 (1) ◽  
pp. 261
Author(s):  
Arthur de Oliveira Lima ◽  
Marcus S. Dersch ◽  
Jaeik Lee ◽  
J. Riley Edwards
Keyword(s):  
Theoretical Calculations ◽  
Single Point ◽  
Point Load ◽  
Railway Track ◽  
Optimized Design ◽  
Wheel Load ◽  
Field Instrumentation ◽  
Stiffness Properties ◽  
Materials Used ◽  
Track Modulus

Ballasted railway track is typically constructed using sleepers that are manufactured from a common material type within a given length of track. Timber and concrete are the two most common sleeper materials used internationally. Evidence from historical installations of interspersed concrete sleepers in timber sleeper track in North America has indicated inadequate performance, due largely to the heterogeneity in stiffnesses among sleepers. Theoretical calculations reveal that interspersed installation, assuming rigid concrete sleepers and supports, can result in rail seat forces more than five times as large as the force supported by the adjacent timber sleepers. Recently, engineered interspersed concrete (EIC) sleepers were developed using an optimized design and additional layers of resiliency to replace timber sleepers that have reached the end of their service lives while maintaining sleeper-to-sleeper stiffness homogeneity. To confirm that the concrete sleepers can successfully replicate the stiffness properties of the timber sleepers installed in track, field instrumentation was installed under revenue-service train operations on a North American commuter rail transit agency to measure the wheel–rail vertical loads and track displacement. The results indicated that there are minimal differences in median track displacements between timber (2.26 mm, 0.089 in.) and EIC sleepers (2.21 mm, 0.087 in). Using wheel-load data and the corresponding track displacements associated with each wheel load, track modulus values were calculated using the single-point load method based on beam on elastic foundation (BOEF) fundamentals. The calculated values for the track modulus indicated similar performances between the two sleeper types, with median values of 12.95 N/mm/mm (1878 lbs./in./in.) and 12.79 N/mm/mm (1855 lbs./in./in.) for timber sleepers and EIC sleepers, respectively. The field results confirmed the suitability of the new EIC sleeper design in maintaining a consistent track modulus for the location studied, thus evenly sharing loads between and among sleepers manufactured from both concrete and timber.

scholarly journals Evaluation and Application of Surrounding Rock Stability Based on the Improved Weighting Multidimensional Cloud Model

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Jing Long Li ◽  
Chao Yuan ◽  
Bo Zhang ◽  
Bin Sui
Keyword(s):  
Evaluation Method ◽  
Cloud Model ◽  
Evaluation Criteria ◽  
Surrounding Rock ◽  
Stability Evaluation ◽  
Weighting Method ◽  
Safety Level ◽  
Rock Stability ◽  
Construction Risk ◽  
Multidimensional Cloud Model

Aiming at the uncertainty in the existing tunnel surrounding rock stability evaluation methods and the inability to make scientific explanations in the process of determining the weights of multiple evaluation indicators, this paper combines subjective weighting based on the nonlinear characteristics of the surrounding rock stability evaluation criteria. Based on the advantages of the method AHP and the objective weighting method CRITIC, a comprehensive weighting method with multiple evaluation indicators is proposed, which is integrated with the multidimensional normal cloud model to establish a surrounding rock stability evaluation method for the improved weighted multidimensional cloud model and accurately obtain the safety level of tunnel surrounding rock construction. The multidimensional cloud model based on improved weighting not only solves the two major problems of randomness and ambiguity in surrounding rock stability evaluation but also fully considers the influence of the information contained in each evaluation factor on the results. The surrounding rock stability evaluation method in this paper is applied to the tunnel construction of the Beijing-Shanghai Expressway and Jinan Expressway connecting line construction project, and the evaluation results have a scientific guiding role for construction risk control.

scholarly journals Stability Evaluation Method of Hole Wall for Bored Pile under Blasting Impact

Symmetry ◽  
2022 ◽  
Vol 14 (1) ◽  
pp. 79
Author(s):  
Qiuwei Yang ◽  
Zhikun Ba ◽  
Zhuo Zhao ◽  
Xi Peng ◽  
Yun Sun
Keyword(s):  
Pile Foundation ◽  
Evaluation Method ◽  
Impact Load ◽  
Stability Evaluation ◽  
Foundation Construction ◽  
Concentration Problem ◽  
Hole Wall ◽  
Failure Theory ◽  
Collapse Failure ◽  
The Stability

Blasting impact load may be encountered during the construction of some pile foundation projects. Due to the effect of blasting impact, hole collapse can easily occur in the hole-forming stage of pile foundation construction. In order to prevent hole collapse, it is very necessary to evaluate the stability of a pile hole wall before pile foundation construction. The calculation of hole collapse can usually be attributed to an axisymmetric circular hole stress concentration problem. However, the existing collapse failure theory of pile hole hardly considers the effect of blasting impact load. In view of this, this paper proposes the stability evaluation method of a pile hole wall under blasting impact. Compared with the existing collapse failure theory, the proposed method fully considers the effect of blasting impact stress. Using Mohr–Coulomb strength theory and symmetry analysis, the strength condition of collapse failure is established in this work for accurate evaluation of the stability of a hole wall. The proposed stability evaluation method is demonstrated by a pile foundation construction project of a bridge. Moreover, a shaking table test on the pile hole model was performed to verify the proposed method by experimental data. The results indicate the effectiveness and usability of the proposed method. The proposed method provides a feasible way for the stability analysis of a pile hole wall under blasting impact.

scholarly journals Stability evaluation method for assessing bedrock and overburden layer slope (BOLS) under seismic load

2021 ◽  
Vol 861 (5) ◽  
pp. 052035
Author(s):  
Weizhi Chen ◽  
Weijing Min ◽  
Yuchun Yao ◽  
Anhong Li ◽  
Yong Liu ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Seismic Load ◽  
Stability Evaluation

Evaluation of the Development Level of China' s Precise Finishing Industry

2006 ◽  
Vol 315-316 ◽  
pp. 864-867
Author(s):  
Shi An ◽  
J. Wang ◽  
J.P. Qian
Keyword(s):  
Analytical Hierarchy Process ◽  
Evaluation Method ◽  
Expert Knowledge ◽  
Comprehensive Evaluation ◽  
Evaluation Criteria ◽  
Development Planning ◽  
Fuzzy Evaluation ◽  
Fuzzy Analytical Hierarchy Process ◽  
Development Level ◽  
Hierarchy Process

Recognizing and evaluating the development level of a country’s precise finishing industry, is the prerequisite to the country’s decision-making on the development planning and guiding policies in this industry. This paper presents a Fuzzy Analytical Hierarchy Process (FAHP) Model on the base of “Expert Knowledge”. This model combines the advantages of Fuzzy Evaluation Method and Analytical Hierarchy Process (AHP), and can give relatively reliable evaluation results with incomplete information of the evaluation criteria. The application of the FAHP Model provide reliable comprehensive evaluation data.

scholarly journals Evaluation Method of Relative Humidity Changes in Below-Grade Concrete Structure Space Depending on Different Waterproofing Material and Installation Method

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 742
Author(s):  
Ki-won An ◽  
Kyu-hwan Oh ◽  
Bo Jiang ◽  
Xingyang He ◽  
Sang-keun Oh
Keyword(s):  
Relative Humidity ◽  
Linear Regression ◽  
Concrete Structure ◽  
Evaluation Method ◽  
Linear Regression Analysis ◽  
Evaluation Criteria ◽  
Cumulative Probability ◽  
Control Performance ◽  
Negative Side ◽  
Positive Side

An evaluation method for assessing the difference in the relative humidity (RH) control performance of waterproofing material is proposed. For a demonstration of this evaluation method, two waterproofing materials (urethane coating and cementitious waterproofing material) installed with different methods (positive and negative side of concrete structure respectively) are exposed to temperature conditions representing three seasonal conditions: Summer (40 °C), spring/autumn (20 °C) and winter (4 °C). Condensation level changes on the inner side of the waterproofing material installed specimen is measured, and for derive criteria for comparison, three parameters based on the average RH, intercept RH (derived from a linear regression analysis of RH measurement), and maximum relative humidity are derived for each different waterproofing material installed specimen. Based on quality specification for underground concrete structures, the demonstration evaluation establishes provisional standard criteria of below 70% RH, and all three parameters are evaluated to determine whether the tested waterproofing material/method complies to the performance requirement. Additional analysis through linear regression and cumulative probability density graphs are derived to evaluate the RH consistency and range parameters. The evaluation regime demonstrates a quantitative RH analysis method and apparatus, and a newly designed evaluation criteria is used to compare the RH control performance of positive-side installed urethane waterproofing materials and negative-side installed cementitious waterproofing material.

scholarly journals Variation of Mechanical Characteristics of Polyurethane Foam: Effect of Test Method

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2672 ◽  
Author(s):  
Ki-Beom Park ◽  
Hee-Tae Kim ◽  
Nam-Yong Her ◽  
Jae-Myung Lee
Keyword(s):  
Polyurethane Foam ◽  
Evaluation Method ◽  
Mechanical Performance ◽  
Cell Structure ◽  
Extreme Environments ◽  
Evaluation Criteria ◽  
Test Method ◽  
Material Behavior ◽  
Insulation Material ◽  
Binding Effect

Polyurethane foam (PUF), a representative insulation material, not only prevents heat conduction but can also support a load. Particular interest in rigid PUF proliferated over the past several years in fields where extreme environments are applied. A closed-cell structure which forms the interior of rigid PUF serves to maximize the utilization of these polymeric foams. Rigid PUF is more sensitive to external conditions such as temperature or restraint than other structural materials such as steel. Depending on the market trends in which utilization of a cryogenic environment is expanding, the tendency of material behavior resulting from the binding effect also needs to be investigated. However, most conventional compression test method standards applicable to rigid PUF do not adequately reflect the restraints. Therefore, this study proposes a method for evaluating the mechanical performance of materials in a more reliable manner than that of conventional tests. Experimental observation and analysis validated this compression evaluation method in which constraints are considered. Consequently, the compressive strength of rigid PUF compared to the results of the conventional test showed a difference of up to 0.47 MPa (approximately 23%) at cryogenic temperatures. This result suggests that there are important factors to consider when assessing performance from a material perspective in an environment where rigid PUF insulation is utilized. It is believed that the test methods newly proposed in this study will provide an experimental framework that can be applied to the evaluation criteria of material properties and reflected in structural design.

scholarly journals A Cross-Efficiency Evaluation Method Based on Evaluation Criteria Balanced on Interval Weights

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1503 ◽  
Author(s):  
Hailiu Shi ◽  
Yingming Wang ◽  
Xiaoming Zhang
Keyword(s):  
Evaluation Method ◽  
Evaluation Criteria ◽  
Evaluation Criterion ◽  
Peer Evaluation ◽  
Data Envelopment ◽  
Efficiency Evaluation ◽  
Common Set Of Weights ◽  
The Cross ◽  
The Difference ◽  
Evaluation Approaches

Cross-efficiency evaluation approaches and common set of weights (CSW) approaches have long been suggested as two of the more important and effective methods for the ranking of decision making units (DMUs) in data envelopment analysis (DEA). The former emphasizes the flexibility of evaluation and its weights are asymmetric, while the latter focuses on the standardization of evaluation and its weights are symmetrical. As a compromise between these two approaches, this paper proposes a cross-efficiency evaluation method that is based on two types of flexible evaluation criteria balanced on interval weights. The evaluation criteria can be regarded as macro policy—or means of regulation—according to the industry’s current situation. Unlike current cross-efficiency evaluation methods, which tend to choose the set of weights for peer evaluation based on certain preferences, the cross-efficiency evaluation method based on evaluation criterion determines one set of input and output weights for each DMU. This is done by minimizing the difference between the weights of the DMU and the evaluation criteria, thus ensuring that the cross-evaluation of all DMUs for evaluating peers is as consistent as possible. This method also eliminates prejudice and arbitrariness from peer evaluations. As a result, the proposed cross-efficiency evaluation method not only looks for non-zero weights, but also ranks efficient DMUs completely. The proposed DEA model can be further extended to seek a common set of weights for all DMUs. Numerical examples are provided to illustrate the applications of the cross-efficiency evaluation method based on evaluation criterion in DEA ranking.

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