PVC drainage connection approval memo, Apr 1985

NYC 9/11 Public Portal Document

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■ HANDBOOK OF I’VC PIPE

TABLE^ 2S - VALUES OF BEDPING CONSTANT; K 26 - AYl BEDDING ANGLE (DEGREES) K

0 0.110 30 0.108 45 0.105 ■ 60 0.102 Soil type“pl| 90 0.096 ■{Unified Cla® 120 -0.090 180 0.083 Finc*grain€'d Soils (t-l," Seih with-medium w Two other observations from Watkins’ work are of particular note: Fine-grained Soils (LL (1) There is little point in evaluating E' by a model testand then using the I / Soils with medium to ■■ ML’CU with fess ■■ modulus to predict ring deflection. The model gives ring deflection directly. ■ particles - .. (2) Ring deflection may not be the only performance limit. -<.. f Fine-grained Soils {LI. , ' Soils vMth medium i< ■ Many research efforts have attempteddo measure E'without success, ML-CL. with moh //The mostuseful method has involved :The measure. of " deflections ” particles y/ ” - Cmrse-grained Soils w I for a" pipe under which other conditions, were known followed by back- ...GM, GC|SM,SC5 c

11 calculation through the modified Iowa Formula to determine the correct Coarse-gained Soils w ' -...-GW, GF. .SW. SF^ fi value of E'. ■'This requires assumptions regarding the load, bedding factor -■ - "Crushed Rock ' ■ / /and deflection 'lag factor to be used and has led to a wide range of reported Accuracy in Terms of »ASTM Oesignalion values of E'.’ " ' • ALL - Liquid limit. One. of the most recent attempts to acquire information on values of - ' ®Or any borderline s '’For xFM accuracy ; .E* was conducted by y^mster K,-Howard, of the United States Bureau ot_ 4U ■Reclamation,. - How.ard reviewed both laboratory, and field data from many : Y f Note: Vai ties ap|B» factor. For use in prec sources. Using information from over 100 laboratory and field tests, forteng-term’defleciM - Howard compiled a table of average E' values’ for various soiT types and lower F’ vjue or density from test sta densities (See Table 26). He was able to do this by assuming values of-E ? T-W. USBR I>signat K and W^, and then back-calculating through the Modified .Iowa Formula to ®®uhck: "soil, reactioi CCAMATIQN, O«

/calculate a theoretical value of deflection. This theoretical deflection'was GIVIIU BH<S|N««1

'then'compared with actual measurements. , By assuming the E* values ot The only p; Table 26, a bedding constant K = 0.1, and deflection-lag factor D|_ " L®' calculate deflectio Howard was able to correlate the theoretical and empirical results to- within that in pipe-soil sy ± 2"percent deflection if he used the prism soil load, .This means that it consolidation' I theoretical deflections, using Table'26, were approximately 5%, measured Maximum load re deflection would range between 3 and 7%, Although the vast, majority of ihat deflections c< data from this study was taken from tests on steel and reinforced plastw •to years. For tU mortar pipe with diameters greater than 24 in., it does provide some usefid ’ion lag factor of 1 information to guide designers of all flexible pipe including PVC pipe since • Time lag wi it helps to give an understanding of the Modified Iowa Deflection Formhl^' ®f this chapter.

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