BS_9295-2020.pdf

BS9295:2020BSI Standards PublicationGuide to the structural design ofburied pipesbsi.BRITISH STANDARDBS9295:20208.1General70Figure 28-Flowchart for design of semi-rigid pipes of ductile iron8.2Installation conditions70Table 24-Semi-rigid pipe embedments71Table 25-Semi-rigid and flexible pipe embedment properties728.3Design pressures for semi-rigid pipes72Table 26-Load coefficients for incomplete projection condition73Figure 29-Deflection lag factor74Table 27-Guide values of Spangler modulus for native soils,E758.4 Semi-rigid pipe embedment properties758.5 Design data for semi-rigid pipes768.6Bedding for ductile iron pipes76Table 28-Embedment classes778.7Simplified bedding table for ductile iron pipes77Table 29-Safe depths of cover(m)for ductile iron water pipe with field surcharge79Table 30-Safe depths of cover(m)for ductile iron water pipe with main road surcharge81Table 31-Safe depths of cover(m)for ductile iron sewer pipe with field surcharge83Table 32-Safe depths of cover(m)for ductile iron sewer pipe with main road surcharge85Annex A(informative)Other design considerations87Figure A.1-Soil loads and stresses produced by surface loads(after Fadum 13)88Figure A.2-Uniform surcharge U/unit area of limited extent in fixed position89Figure A.3-Pipe in tunnel,heading or jacked into place90Figure A.4-Multiple pipe trenches92Figure A.5-Uneven loading of multiple pipes laid in parallel93Figure A.6-Circumstances which can result in large lateral loads:Embankment94Figure A.7-Schematic of groundwater flotation forces96Figure A.8-Pipelines in poor ground98Figure A.9-Use of geotextile around pipe embedment99Figure A.10-Pipeline on piles100Table A.1-Recommended maximum length of rocker pipes101Figure A.11-Protection of a shallow pipeline using concrete surround104Figure A.12-Protection of shallow pipeline with a slab105Figure A.13-Plain and reinforced beddings and surrounds107Figure A.14-Pipework under a floor slab108Figure A.15-Pipework built in to the wall109Figure A.16-Pipework passing through the wall109Table A.2-Overview of limit state conditions to be checked for longitudinal effects111Table A.3-Compaction fractions for bedding materials115Table A.4-Gradings116Table A.5-Maximum recommended level of impurity(by mass)116Table A.6-Equation errors(percent)118Bibliography135Summary of pagesThis document comprises a front cover,and inside front cover,pages i to vi,pages 1 to 137,an inside back coverand a back cover.THE BRITISH STANDARDS INSTITUTION 2020-ALL RIGHTS RESERVED III