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Design Safety
Published in Zohrab A. Samani, Hydraulic and Hydrologic Engineering, 2022
SDR = standard dimension ratio SDR=ODthOD = average outside diameterth = wall thickness
Buckling of HDPE liners under external uniform pressure
Published in Mark Knight, Neil Thomson, Underground Infrastructure Research, 2020
R.M. Bakeer, S.E. Pechon, J.E. Taylor, S. Chunduru, M.E. Barber
where Pcr = critical buckling pressure, or equivalent water head pressure; E = time-dependent modulus of elasticity; C = reduction factor to account for liner ovality; α = lining factor; β = stress concentration factor; v= Poisson’s ratio; SDR = Standard Dimension Ratio; and FS = factor of safety. The Standard Dimension Ratio (SDR) is an industry standard that defines the required minimum thickness of a pipe wall (t) as a function of its nominal diameter (D).
Local Buckling of Buried HDPE Pipelines Subjected to Earthquake Faulting: Case Study Via Numerical Simulations and Experimental Testing
Published in Journal of Earthquake Engineering, 2020
Xiaojian Xie, Michael D. Symans, Michael J. O’Rourke, Tarek H. Abdoun, Da Ha, Thomas D. O’Rourke, Michael C. Palmer, Jeremiah Jezerski, Harold E. Stewart
The experimental investigation involved testing of small-scale HDPE pipe specimens within the centrifuge split-box containers. The pipe had an outer diameter D = 33.4 mm, a wall thickness t = 1.96 mm, and a Standard Dimension Ratio (SDR) = D/t = 17. The centrifuge tests were carried out at a gravity level of 12.2 g. Hence, the model geometry simulates a prototype pipe with D = 407.5 mm and t = 24.0 mm. The length of the prototype pipe is 15.6 m and the soil dry unit weight is 14.7 kN/m3 with a moisture content w = 4.5% and peak friction angle = 40°. To capture the behavior of the pipe during the offset, two types of measurement sensors were used. In some tests, the HDPE pipe was instrumented with strain gages that were attached along the pipe spring-line and hence measured the strain distribution along the length of the pipe. In other tests, tactile pressure sensors were wrapped around the pipe circumference near the fault and hence measured the circumferential and longitudinal pressure distribution. The tests were specifically designed to determine the influence of fault crossing angle (positive angles only) on pipe response. Figure 1 shows the set-up of the RPI centrifuge split-box tests along with the shape of the model pipes before and after offset for an initial fault crossing angle of 60° and a prototype offset of approximately one meter [2 x 0.04 x 12.2]. The ends of the pipe were clamped to an aluminum alloy connector which was connected to the split-box through a spherical bearing that provided freedom to rotate (thus, the pipe ends were effectively pinned). Additional details on the centrifuge test set-up can be found in Ha et al. [2010].