Influence of screw pile installation on the stress state in the soil

2020 ◽  
pp. 3-19
Author(s):  
W.F. Van Impe ◽  
H. Peiffer
Keyword(s):  
Stress State ◽  
Pile Installation ◽  
Screw Pile

scholarly journals Effects of screw pile installation on installation requirements and in-service performance using the Discrete Element Method

2020 ◽  
Author(s):  
Yaseen Umar Sharif ◽  
Michael Brown ◽  
Benjamin Cerfontaine ◽  
Craig Davidson ◽  
Matteo Oryem Ciantia ◽  
...  
Keyword(s):  
Discrete Element Method ◽  
Large Diameter ◽  
Compressive Force ◽  
Vertical Displacement ◽  
Discrete Element ◽  
Service Performance ◽  
Pile Installation ◽  
Screw Pile ◽  
Torque Capacity ◽  
Element Method

Existing guidance on the installation of screw piles suggest that they should be installed in a pitch-matched manner to avoid disturbance to the soil which may have a detrimental effect on the in-service performance of the pile. Recent insights from centrifuge modelling have shown that installing screw piles in this way requires large vertical compressive (or crowd) forces, which is inconsistent with the common assumption that screw piles pull themselves into the ground requiring minimal vertical compressive force. In this paper, through the use of the Discrete Element Method (DEM), the effects of advancement ratio, i.e. the ratio between the vertical displacement per rotation to the geometric pitch of the helix of the screw pile helix, on the installation resistance and in-service capacity of a screw pile is investigated. The findings are further used to assess the applicability of empirical torque capacity correlation factors for large diameter screw piles. The results of the investigation show that it is possible to reduce the required vertical compressive installation force by 96% by reducing the advancement ratio and that although over-flighting a screw pile can decrease the subsequent compressive capacity, it appears to increase the tensile capacity significantly.

scholarly journals Control of screw pile installation to optimise performance for offshore energy applications

Géotechnique ◽  
2021 ◽  
pp. 1-52
Author(s):  
Benjamin Cerfontaine ◽  
Michael John Brown ◽  
Jonathan Adam Knappett ◽  
Craig Davidson ◽  
Yaseen Umar Sharif ◽  
...  
Keyword(s):  
Energy Applications ◽  
Pile Installation ◽  
Screw Pile

Short Stress State Questionnaire

2015 ◽  
Vol 31 (1) ◽  
pp. 20-30 ◽  
Author(s):  
William S. Helton ◽  
Katharina Näswall
Keyword(s):  
Stress State ◽  
Factor Structure ◽  
Human Performance ◽  
Self Report ◽  
Confirmatory Factor ◽  
Stress States ◽  
Related Stress ◽  
Using Data ◽  
Task Conditions ◽  
Multiple Samples

Conscious appraisals of stress, or stress states, are an important aspect of human performance. This article presents evidence supporting the validity and measurement characteristics of a short multidimensional self-report measure of stress state, the Short Stress State Questionnaire (SSSQ; Helton, 2004 ). The SSSQ measures task engagement, distress, and worry. A confirmatory factor analysis of the SSSQ using data pooled from multiple samples suggests the SSSQ does have a three factor structure and post-task changes are not due to changes in factor structure, but to mean level changes (state changes). In addition, the SSSQ demonstrates sensitivity to task stressors in line with hypotheses. Different task conditions elicited unique patterns of stress state on the three factors of the SSSQ in line with prior predictions. The 24-item SSSQ is a valid measure of stress state which may be useful to researchers interested in conscious appraisals of task-related stress.

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