scholarly journals Effect of Boundary Conditions on the Mechanical Behavior of the Geogrid–Soil Interface

2021 ◽  
Vol 11 (21) ◽  
pp. 9942
Author(s):  
Zheng Zuo ◽  
Guangqing Yang ◽  
Zhijie Wang ◽  
He Wang ◽  
Jing Jin

Geogrid-reinforced structures are extensively adopted in various engineering fields. At present, the influence of boundary conditions was not considered in design methods, bringing hidden dangers to the safety of the structure. In the current study, a series of pullout tests were carried out on high-density polyethylene (HDPE) geogrid-reinforced coarse sand. The magnitude and growth pattern of pullout resistance and the variation laws of interfacial shear strength indexes under four types of boundary conditions were analyzed. Additionally, the boundary reduction coefficient (BRC) was introduced to establish the relationship between rigid and flexible boundary for the design of the structure. The tests results showed that the boundary conditions cannot be ignored in the design of structures, especially in the front. When the normal loading was up to 120 kPa, the BRC-top and BRC-positive could be taken as 0.9 and 0.5, respectively, and verified by fitting results. The boundary conditions affected the pullout resistance, while the vertical loading corresponding to the maximum pullout resistance was not related to boundary conditions. Investigating the interaction of the geogrid–soil under different boundary conditions can help to improve the understanding of the behavior of reinforced soil structure, and to achieve a more efficient and economical design.

1993 ◽  
Vol 30 (3) ◽  
pp. 409-417 ◽  
Author(s):  
R.J. Fannin ◽  
D.M. Raju

Pullout tests are reported on geosynthetic test specimens embedded in a relatively dense, coarse sand sample. The tests are displacement controlled and are performed at different vertical effective stresses. Tests are reported for a smooth and textured geomembrane and for geogrids of a high and low junction strength. Behaviour is compared with an inextensible, rough sheet. Pullout resistance is governed by progressive tensile strain in the geosynthetic which is a result of relative displacement between it and the soil. Values of interface bond that are described by an interaction factor vary significantly and are stress dependent. Both types of geogrid and the textured geomembrane exhibit a similar response to loading at small displacement, and mobilize a much larger interaction factor than the smooth geomembrane. A rationale is suggested for selection of appropriate values in design. Key words : pullout testing, geogrid, geomembrane, interface friction, reinforced soil.


2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Zheng Zuo ◽  
Guangqing Yang ◽  
He Wang ◽  
Zhijie Wang

This paper describes a series of laboratory pullout tests that were performed to investigate the pullout behavior of high-density polyethylene (HDPE) uniaxial geogrid subjected to static and dynamic loading. Pullout tests were conducted on HDPE geogrid reinforced coarse sand under normal static loading (60–300 kPa), dynamic loading with different amplitudes (20, 40, and 60 kPa), and different frequencies (2, 4, and 6 Hz) by using the newly developed pullout apparatus. The results indicated that the pullout resistance of geogrid presented different growth patterns with the increase of normal loads under static loading. The amplitude and frequency both had significant effects on the interaction between reinforcement and soil, and the increment of the pullout resistance was 0.6 kN and 0.3 kN, respectively. The effect of dynamic loading on the soil-geogrid interface can be gradually equivalent to that of static loading corresponding to the balance position of dynamic loading with the increase of frequency compared with the static loading. The results of this study are helpful for the selection of the strength of the reinforcement in different locations and to simplify the study on the stress of reinforcement in reinforced soil structures under traffic loads.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Irem Demirkan ◽  
Ravi Srinivasan ◽  
Alka Nand

PurposeThis paper explores the role of effective resource and knowledge management capabilities on product innovation capabilities of the small and medium-sized enterprises (SMEs). Specifically, the authors research the role of the human resource investments in the form of employee training in developing firm's innovation capabilities and how SMEs manage these investments when we account for the boundary conditions such as the level of employee education, SME size and the frequency of investments in research and development (R&D).Design/methodology/approachThe authors use survey data conducted by The Centre for European Economic Research (Zentrum für Europäische Wirtschaftsforschung – ZEW). The final sample for analysis includes 983 SMEs from Germany that belong to 13 different industries. The authors use hierarchical OLS regression to test the hypotheses presented in this paper.FindingsThe authors find a positive association between increased investments in employee training and product innovation capabilities in the context of SMEs. More specifically, the authors’ findings support that (1) the relationship between employee training and innovation capabilities is weaker in industries with greater proportion of employees with university degrees, (2) the effectiveness of investments in employee training is lower among larger SMEs than smaller SMEs, and (3) continuous R&D weakens the relationship between training expenditure and innovation capabilities. While on the one hand the authors’ findings contribute to the debate of whether employee training is necessary for SMEs by affirming this notion, on the other hand the authors show that investments in employee training have differing implications for small and large SMEs within boundary conditions. Moreover, these findings have practical implications for the managers of all SMEs in terms of management of their knowledge resources.Research limitations/implicationsThe authors’ research makes important contributions to the study of innovation in SMEs. First, the authors contribute evidence to the debate whether employee training is necessary for SMEs by showing that employee training is particularly important for SMEs that are smaller in size, have lower proportion of employees with university degrees and when they invest in research and development in a targeted manner. The authors also demonstrate that investments in employee training is not a waste, rather such investments can increase the likelihood of survival for many of these firms through its positive impact on product innovation.Practical implicationsFor managers of SMEs, the authors’ findings suggest that while investments in employee training are important, the managers of particular SMEs with above-mentioned qualities should be persistent in such investments and must make deliberate efforts to reap the benefits in terms of innovative capabilities. Unlike large firms, who have the financial means to carry out investments in an abundant manner, SMEs appear to be more enterprising with their scarce resources when we also consider the role of investments in human resources.Originality/valueThe authors’ research makes important contributions to the study of innovation in SMEs. First, the authors contribute evidence to the debate whether employee training is necessary for SMEs by finding that employee training is particularly important for SMEs that are smaller in size, have lower proportion of employees with university degrees and when they do not invest in R&D continuously. The authors also demonstrate that investments in employee training is not a waste, but such investments can increase the likelihood of survival for many of these firms.


1996 ◽  
Vol 23 (4) ◽  
pp. 838-849 ◽  
Author(s):  
Hesham Mohammed ◽  
John B. Kennedy

Soil – metal structures consisting of metal conduits covered with soil have been used extensively for short-span bridges. Recently, some designers ventured into utilizing them for longer spans with shallow soil cover which has led to some failures. Long-span soil – metal structures are often designed with transverse stiffeners attached to the metal structure. Another approach is the use of a reinforced-soil system in which the surrounding soil is reinforced and the metal conduit is tied into the soil. In this paper, a three-dimensional analysis of long-span soil – metal structures is carried out using these two approaches. The analysis is verified and substantiated by results from laboratory models. The structural responses from the two designs show that the latter design approach leads to a more economical structure. A design example based on the Cheese Factory Bridge built in Ontario in 1984 is presented. Key words: bridges, design, long span, reinforced soil, soil – metal structures, structural engineering, three-dimensional analysis.


2015 ◽  
Vol 20 (1) ◽  
pp. 81-100 ◽  
Author(s):  
Eun Young Nae ◽  
Hyoung Koo Moon ◽  
Byoung Kwon Choi

Purpose – The purpose of this paper is to investigate the boundary conditions in the relationship between feedback-seeking behavior (FSB) and work performance. The authors hypothesized that the positive influence of employees’ FSB on their work performance is influenced by perceived quality of feedback. The authors also expected that employees’ trust in their supervisors moderated the interaction between their FSB and perceived feedback quality. Design/methodology/approach – Data were collected from 202 employees in South Korea. A hierarchical multiple regression analysis was performed to test the hypothesis. Findings – The results showed that while employees’ FSB was positively related to work performance, the influence was stronger for employees who perceived they were receiving high quality of feedback from supervisors. The authors also found that the moderating effect of feedback quality on the relationship between FSB and work performance was stronger when employees had high levels of trust in their supervisors. Practical implications – The findings suggest that if managers wish to encourage employees to achieve work goal and desirable performance levels by actively engaging in FSB, they should pay more attention to providing high quality of feedback and building trust with employees. Originality/value – This study contributes to expand the understanding of FSB-work performance relationship by verifying the boundary conditions, which suggests the importance of examining the moderating factors in the FSB mechanism.


2000 ◽  
Vol 122 (2) ◽  
pp. 213-218 ◽  
Author(s):  
Hung-Ming Tai ◽  
Cheng-Kuo Sung

This paper investigates the effects of belt flexural rigidity and belt tension on transmission error of a carriage-driving system. The beam model associated with both the clamped and moving boundary conditions at two ends is utilized to derive the governing equation of the belt. The belt flexural rigidity is obtained and verified by an experimental technique. In addition, a numerical method is proposed to determine the belt profile, transmission error and transmission stiffness. Results show that transmission error of a carriage-driving system increases when the carriage moves away from the driving pulley due to finite belt flexural rigidity. According to the analyses, application of appropriate tension on the belt can significantly reduce the error. Furthermore, the transmission stiffness for representing the entire rigidity between the carriage and pulley is investigated based on the proposed beam model. A three-dimensional plot that indicates the relationship among the transmission stiffness, belt tension and the position of the carriage is obtained. [S1050-0472(00)01102-8]


2019 ◽  
Vol 57 (8) ◽  
pp. 2010-2031 ◽  
Author(s):  
Kaidi Zhang ◽  
Xiao Jia ◽  
Jin Chen

PurposeThe emerging natures of big data – volume, velocity, variety, value and veracity – exert higher stress on employees and demand greater creativity from them, causing extreme difficulties in the talent management of organizations in the big data era. The purpose of this paper is to explore the effect of challenge stressors on creativity and the boundary conditions of the relationship.Design/methodology/approachMultisource data were collected including 593 followers and their 98 supervisors from organizations that are confronting a big data induced management revolution. Hierarchical regression analysis and bootstrapping analysis were used to test the mediation and moderation mechanism.FindingsThe results showed that job burnout mediated the negative relationship between challenge stressors and creativity and that this indirect effect was attenuated by an employee’s core self-evaluation (CSE) and servant leadership. In contrast, whether work engagement mediated the relationship between challenge stressors and creativity was contingent on the level of an employee’s CSE and servant leadership. Specifically, the mediating effect was significant only when an employee’s CSE or servant leadership was high.Originality/valueThe results contribute to our understanding of the relationship between challenge stressor and creativity in the big data era. Specifically, relying on the job demands–resources model, this study empirically opens the “black box” between challenge stressors and creativity by exploring two opposing intermediate mechanisms. In addition, this study reveals boundary conditions by investigating dispositional and contextual factors that can accentuate the positive effect while attenuating the negative effect of challenge stressors on employee creativity.


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