PVC drainage connection approval memo, Apr 1985

CHAWER V “ DESIGN

<,4 average values of modulus of toil reaction, E' ^CONSTANT, K fABLE 26 —Initial flexible Pipe Deflection) I of Compaction of Beddmg, K f; • for Degree in pound# per square inch Moderate, High, Slight, 0.110 ■' < 85% 86%'95% 95% 0.108 Proctor, Proctor, proctot/ Illi 111 * 40%-70* >70% 0.105 <40% reSattv® retattve relative 0.102 SoiHype-pipe bedding material density density (Unified Classification Syatam*) ' . Pumped ; density 0.096 W j !3) (4) 0.090 _ -1’1_____ Fine-grainsd Soils (LL > 50)* No data available; consult a comprtenl < 0.083 , Soils with medium IO high ptetjeity - . soils engineer; < ' CH. Tk are of particular note, Soils (LL < 50) -. Soils with medium to no plasticity CL, ML, I I el test and then using the ML-CL, with less than 25% coatse-grained 200 400 1,000.L 50 s ring deflection directly, ■ particles pneigraioed Soils (LL < 30) ce-hmit. Soils with medium to no plasticity CL. ML, •asure E' without success ; ML-CL, with more than coarse-grained 400 iS» 2;t» 100 ' ' -pgrlides ,r measure of defleetioib 'Coarse-grtuoed Soils with Fines •' GM, CO SM, SO contains more than 12% fines' lown followed by back- * Coarse-grained Soils with Little or No Fines "....... 3,000/ .o determine the correct .GW.-GP.\SW, SP='contains less than 12% fines " 200 : l*®-« I- _j.(W0- xaST" 'ugr" 3.000- -. ±1 the load, bedding factoi Accuracy in Terms of Percentage Oeflection^ | a* wide range of reported *ASIM OesfgnaDofl D'29Hi, USHR DesignaUon F t

nl'ormation on values of I "% 6'Or LL any ■■ - with one'of these symbols (i.e., GM’GC.’GG-SO." limit.soitbegjnmrtg borderline - Liguid ^For *J% accuracy and predicted dcfkclion of 3%, actual deflection would be between 2S and 4%/’ ■ . ■■■ ■ ■ ■■ X. '■■■ I. ' ' % '' - ■ A " .... ■■ ■■ —- 2 ..I; I Note:Vgdues, applicable only for frlb Jess than 50 ft (15 m>. Table does not'include any safety Inited States Bureau of t -factor. For use in predicting initial deflections only, appropriate Deflection Lag Factor must fee applied id. field data from many for long-term deflections^ If bedding falls on the borderline between two compaction categories, select

ratory and field tests, A lower £' value or average the-fwo values. Percentage Proctor based on laboratory maximum dry ' - ti. 'density from"itst-standards' using'about 42,5^ ft4bZbu ft (598,l/fh’>fXSTM AASHO„ ■ various soil types and " *■ T-^,'USBR 0^igWibnJE4l). Lpsi *"0 kN/mV- " . <■ ■ ’ assuming values of E', '*«««. weACTiON FOR BVRiae pjpe" «y AMsreR k. mowaro, u. s. BURsay or r«- CUAMATION, OeHVBR, qOCORAOO. RKPRIMTKO WITH PeRMIS'SION f»RC>M AMKHICAM SOCmTY OR ■■

CIVIC KUCJRKeSfS jaoRHAA. OR OBOT!gCHNlC.,A^- CWOj|f4'ggR|NG piyi«IOiM. /AWUARV I>7?, PF. 3>-*3. lified Iowa Formula to ill} jretical deflection was ■.The only parameter remaining in the Iowa Formula now needed to" iroing the E' values of calculate deflections is the deflection lag factor D^ . Spangler recognized t n lag factor D^_ = 1.0, that-in pipe-soil system's, as with all engineering systems involving'soil,'The I irical results to within , soil consolidation' at the sides of the pipe continues with time after the . 5

maximum load reaches the top of the- pipe. His experience had shown laSBl t.. This means that if mately 5%, measured that deflections could increase by as much as 30 percent over a period of t the vast majority of -9^ 40 years. For this reason he recommended the incorporation of a deflec­ nd reinforced plastic ; tion lag factor of 1.5 as a conservative design procedure. »provide some useful y II Time lag will be discussed in much greater, detail in another section idihg PVC pipe since Deflection Formula.. • of'this chapter . 143

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