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11/13/2019 About me Buried Concrete Structure Sammy Wong P.Eng., M.E.Sc. 20 + years in Precast Concrete Industry Design for sustainability and resiliency P.Eng., Designated Consulting Engineer Nov 13, 2019 PCI Certified Level III

  1. 11/13/2019 About me Buried Concrete Structure Sammy Wong P.Eng., M.E.Sc. ❑ 20 + years in Precast Concrete Industry Design for sustainability and resiliency ❑ P.Eng., Designated Consulting Engineer Nov 13, 2019 ❑ PCI Certified Level III ❑ PhD Candidate, Western University ❑ Design, manufacture, quality assurance, construction, inspection … LS Wong and Associates 2 1 2 About me Agenda ❑ Projects ❏ 407 East Extension Ph 1 & 2 ❑ Buried structure 101 ❏ MTO Bridges and Culverts ❑ CSA S6 Section 7 ❏ Eglinton Crosstown LRT Stations ❑ Research and Development ❑ Precast Concrete ❏ Fiber reinforced pipe ❑ Case Studies ❏ Lined concrete pipe ❏ Concrete temperature monitoring and control ❑ Design for sustainability and resiliency ❏ RCP Joint performance ❑ Industry exposure CSA A257, CSA S6, CCPPA, OCPA, CPCQA, ACI 3 4 3 4 Buried Concrete Structure 101 What is buried structure? Any structure that is buried underground that is subject to soil-structure interaction. 6 5 5 6 1

  2. 11/13/2019 You can bury any structures … “a structure that has one or more conduits and is designed by taking account of the interaction between the conduit wall and engineered soil ” CSA S6-14 7 8 7 8 Buried Structure Types Rigid Pipe Rigid Flexible Rigid pipe takes more loads loads than soil because its relative stiffness is Rigid Pipe higher. Flexible Stiff Flexible 9 https://en.wikipedia.org/wiki/Drainage#/media/File:Hd pe_pipe_installation.jpg 10 9 10 Flexible Pipe Soil Arching Prism Prism load load Surrounding Soil Flexible pipe deforms loads Settles under load so Reference line Soil settlement line surrounding soil takes Flexible Flexible Rigid Surrounding Pipe Pipe Pipe more loads than the soil settles Deform under pipe because its relative load stiffness is lower. Stiff Flexible Stiff negative arching positive arching A f < 1 A f > 1 11 12 11 12 2

  3. 11/13/2019 Earth Pressure Distribution Buried Structure ❑ Flexible Pipe ❑ Rigid Pipe Rigid Flexible Material strength Soil strength https://www.waterworld.com/municipal/drinking- water/distribution/article/16190949/choosing-the- 13 14 right-pipe-material 13 14 Geometry Buried Concrete Structure Concrete Pipe Box Culvert Three-sided structure ❑ Circular or ❑ Standard size up ❑ Flat top or curve top Design Fundamentals elliptical to 3m span ❑ Larger span up to ❑ Standard size up ❑ Span up to 8m Geometry 16m ❑ Larger cross ❑ Require footing to 3m and readily Earth Load available section area Live Load ❑ Standard Bedding installation Backfill 16 15 15 16 Earth Load on Pipe Buried Concrete Structure ❑ Trench ❑ Embankment ❑ Tunnel 0.3 – 3.0 m Concrete pipe 1.2 – 8.0 m Box culvert 3.6 – 14.4 m Semi-arch 2.4 – 16.0 m 3-sided culvert 3.7 – 25.6 m Full arch 18 17 17 18 3

  4. 11/13/2019 14 Load Coefficient, C d B d Earth Load on Pipe - Trench 12 B d ❑ Soil settlement 10 causes friction 8 ❑ Earth load, W d 𝐼 Prism H 𝐶 � Load 6 � (4 − 𝜌)𝛿 � � + 𝐸 � H 𝑋 � = 𝐷 � 𝛿 � 𝐶 � 4 8 Where, load coefficient 2 𝐷 � = 𝑔( 𝐼 , 𝐿𝜈′) � 𝛿 � 𝐶 � 𝐶 � D o 0 1 2 3 4 5 𝐷 � = 𝑔( 𝐼 , 𝐿𝜈′) 19 𝐶 � 20 19 20 14 Load Coefficient, C d B d Earth Load on Pipe 12 ❑ Trench width 10 increase, the frictions � 𝛿 � 𝐶 � 8 from the wall 𝐼 𝐶 � reduces B d 6 H 4 2 0 1 2 3 4 5 𝐷 � = 𝑔( 𝐼 , 𝐿𝜈′) 𝐶 � 21 22 21 22 Earth Load on Pipe Earth Pressure Distribution - Pipe ❑ Embankment ❑ Heger’s pressure 1.35 1.45 condition distribution ❑ Prism Load, PL ❑ Based on bedding type H H PL 𝑄𝑀 =  � 𝐼 + 𝐸 � (4 − 𝜌) 𝐸 � 8 PL  VAF ❑ Vertical Arching Factor, 0.62 Type 1 Installation VAF = 1.35 – 1.45 1.42 Type 4 Installation ❑ Earth Load, W E D o 𝑋 � = 𝑄𝑀 × 𝑊𝐵𝐺 23 24 23 24 4

  5. 11/13/2019 Bedding Preparation Bedding Preparation Embankment Trench D 0 /6 Min. D 0 D 0 Min. Springline Lower side fill Lower haunch Bedding compaction compaction CSA S6-14 Section 7.8 25 26 25 26 Box Culvert Earth Pressure Distribution - Box Trench Embankment Vertical Arching Vertical Arching Prism Load =  s H Type B2 = +35% L 0 /6 Min. Type B1 = +20% L 0 L 0 /2 Min. W e = A f  s H Horizontal Arching Horizontal Arching Type B2 = 0.25-0.5 Type B1 = 0.3-0.5 Simplified Actual Side fill Bedding Bearing Pressure compaction distribution compaction 27 28 27 28 Live Load Highway (Ontario) Truck ❑ Highway truck ❑ Airplane ❑ Railway ❑ Construction 29 30 29 30 5

  6. 11/13/2019 Highway (Ontario) Truck CL625-ONT Single Wheel Tire Footprint P = 87.5 kN 0.6m 0.25m Tire Footprint 0.6 x 0.25m 2 3.6m 1.2m 6.6m 6.6m H Distribution through soil Per wheel 25kN 62.5kN 87.5kN 87.5kN 75kN (0.6 + 1.75H) x (0.25 + 1.75H) m 2 Per axle 50kN 125kN 175kN 150kN Total 625kN 31 32 CSA S6-14 cl.6.12.6 31 32 Highway (Ontario) Truck CL625-ONT Wheel Load Distribution Tire Footprint 0.6 x 0.25m 2 P = 87.5 kN x 2 = 175 kN 3.6m 1.2m 6.6m 6.6m Tire Footprint 0.6 x 0.25m 2 0.7m<H<1.4m Spread b Per wheel 25kN 62.5kN 87.5kN 75kN (2.4+1.75H) Per axle 50kN 125kN 175kN 150kN Spread a Total 625kN (0.25 + 1.75H) 33 34 33 34 Highway (Ontario) Truck CL625-ONT Wheel Load Distribution Tire Footprint 0.6 x 0.25m 2 P = 62.5 kN x 4 = 250 kN 3.6m 1.2m 6.6m 6.6m Tire Footprint 0.6 x 0.25m 2 H>1.4m Per wheel 25kN 62.5kN 87.5kN 75kN Spread b Per axle 50kN 125kN 175kN 150kN (2.4+1.75H) Spread a Total 625kN (1.45 + 1.75H) 35 36 35 36 6

  7. 11/13/2019 Wheel Load and Axial Influence Combined Wheel and Earth Load 100 100 P=87.5kN 90 90 P=175kN P=250kN 80 80 70 70 Load (kPa) Load (kPa) 60 60 WL 50 50 WL1 40 40 WL2 30 30 WL3 20 20 10 WL 10 0 0 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 Depth (m) Depth (m) 37 38 37 38 Other Live Loads Fluid Load ❑ Hydrostatic internal load ❑ Not pressurized ❑ maximum sectional stresses: exclude fluid load ❑ Bearing pressure: consider fluid load ❑ B777, A380 39 40 39 40 Ground Water Buoyancy ❑ Earth load and hydrostatic pressure ❑ Displaced volume ❑ Submerged soil weight,  sw Earth Load ❑ F.S. = �������� �����  s (H-H w ) ❑ Hydrostatic pressure,  w (No arching) H ������ ����� ❑ F.S. > 1.2 – 2.0 H w ❑ Concrete Pipe Weight  s H Buoyancy Force vs  w H w for Pipe Friction Plastic � 𝜌(𝐸 � 2 ) � 𝛿  sw H w 41 42 41 42 7

  8. 11/13/2019 Buoyancy Can Be a Problem for Flexible Pipe Three-sided culvert ❑ Open bottom culvert ❑ Structure over existing conditions 43 44 https://ccppa.ca/flotation-of-circular-pipe/ 43 44 Precast three-sided culvert Top Slab Rise Side wall Haunch Span Footing ❑ Flat top ❑ Curve top ❑ 2.4m to 16m span ❑ Thinner slab ❑ Flexible geometry ❑ 3.66m – 14.4m span ❑ Standard geometry 45 46 45 46 Loads on Three-sided Culvert Road Surface H Engineering Fills Natural H.W.L Earth Creek 47 48 47 48 8

  9. 11/13/2019 Loads on Three-sided Culvert Wheel Loads Vertical Arching Vert. Earth H 1.2-1.35 Load Hor. Earth Pressure H.W.L 0.35-0.5 Hor. Rx Vert. Rx Pin-pin connection Earth Pressure Hydrostatic Pressure Footing 49 50 49 50 Loads on Arch Culvert Loads on Arch Culvert Wheel Loads Road Surface Vert. Earth Vertical Arching H H Load Compression Engineering Fills Hor. Earth Pressure Natural H.W.L H.W.L Earth Hor. Rx Vert. Rx Creek Pin-pin connection Earth Pressure Hydrostatic Pressure Footing 51 52 51 52 Loads on Arch Culvert (During Construction) Takeaways in this section ❑ Buried structure shall be designed to Negative Moment withstand underground condition ❑ Rigid structure generates positive soil arching attracting more earth load Hor. Earth Pressure ❑ Bedding is important which impact the Hor. Rx load taken by the structure ❑ Compaction of the side fills are important Vert. Rx Pin-pin connection 53 54 53 54 9

  10. 11/13/2019 CSA S6 CHBDC Section 7 Buried Structures CSA S6 Section 7 - 2019 48 pages 49 pages 2019 64 pages 2006 2014 56 55 55 56 2019 2014 Title 7.1 7.1 Scope Highlights 7.2 7.2 Definitions ❑ Durability and sustainability (7.5) [NEW] 7.3 7.3 Abbreviation and symbols ❑ Refined analysis (7.5.5) 7.4 7.4 Hydraulic design ❑ Geotechnical considerations are merged 7.5 7.5 Design from 7.6, 7.7, 7.8 into 7.5.7. 7.6 7.6 Soil-metal structures ❑ Buried structure in cold region 7.5.10 [NEW] 7.7 7.7 Metal box structures ❑ Three-sided structure (7.8) [NEW] 7.8 7.8 Reinforced concrete pipe, boxes, and three-sided buried ❑ Arch structure (7.9) [NEW] structures 7.9 - - Reinforced concrete buried arches 57 58 57 58 7.5.5 Refined methods of analysis 7.5.1 Sustainability and Durability for buried structures ❑ Provide guidelines ❑ Section 2 ❑ Modeling requirements Durability ► Durability and sustainability ❏ Soil-structure interaction ❏ Boundary condition ❏ Response impacted by the engineered fill envelop ❑ Material properties: structure and soil 59 60 59 60 10

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