Engineering Presentation Soil type classification Gravel sand silt

Engineering Presentation

• Soil type classification • Gravel, sand, silt, clay • Soil strength classification • Granular soils (sand gravel) • Loose • Dense • Cohesive soils (silt and clay) • Soft - toothpaste • Hard – difficult to mark with your fingernail Basic Soil Mechanics

• Soil borings • Drill holes, take samples • Types of samples • Undisturbed – Driven Tubes • Disturbed - Bags • Logs • Soil tests • N-Values – Drive Blow Counts • Shear Strength – Direct Shear Test • Moisture/density • Compressibility – Consolidation Test • Expansion Index • Chemical Tests - Corrosion Investigations

• Standard Test Penetration Test Video Standard Penetration Test

• Bucket Auger Drill Rig Video Bucket Auger Drill Rig

• • • Fill Settlement Expansive Soil Movement Slope Creep Land Slides Liquefaction Typical Soil Problems

• Thickness • Age • Soil type Fill Settlement

• • • Shrinks when dry – summer Swells when wet – winter Plumbing leaks Timing of movement Maintenance Expansive Soil

Lift and Separation Between Sidewalk and Wall Examples of Poor Site Maintenance

Separation Between Landing and House Pavement Damage Examples of Poor Site Maintenance

Pavement Damage Examples of Poor Site Maintenance

Pavement Damage Wall Damage Examples of Poor Site Maintenance

Wall Damage Wall Tilt Examples of Poor Site Maintenance

Wall Damage Slope Between Building and Wall Examples of Poor Site Maintenance

• Upper 5 to 10 feet – 3: 1 (horizontal: vertical) or steeper slopes • Usually expansive soils • Slope maintenance Slope Creep

Slope Creep

Wall is Tilted Crack in Seam Between Ceiling and Wall Effect of Poor Slope Maintenance

Wall is Tilted Cracks in Foundation Effect of Poor Slope Maintenance

Crack in Wall Crack Radiating From Window Effect of Poor Slope Maintenance

• Deep (typically more than 5 feet) • Large, affecting more than one property • Different types • mud flows – very fast • Circular – slow – 1 inch per year or less Landslides

• Landslide Video Landslides

Signs of Movement

Slope Movement

Slope Movement

Foundation Clearances From Slope

Examples of Lateral Movement

Examples of Lateral Movement

Examples of Lateral Movement

Examples of Lateral Movement

Examples of Lateral Movement

• Loose sand below water table during earthquake. • Liquefaction Potential Maps • Definition of Water Table Liquefaction

• Pier spacing is usually 5 feet to 7 feet, depending on foundation loads. • Some buildings are heavier than others (masonry v. wood frame, multi-story vs. single-story). • Some buildings have interior and exterior spread footings that support heavy loads. • Most footings are designed to support 1500 psf – 2500 psf. • 5’ x 5’ footing could support 62, 500 lbs. • 2’ wide perimeter footing could support up to 5, 000 lbs/ft. Pier Spacing

Typical Residential Building Loads

• Line Loads – Along exterior walls • 1000 lbs/ft. /floor (typical) • Concentrated Loads – Below columns • 2000 lbs/sq. ft. (typical) • 5 ft. square footing = 50, 000 lbs Types of Building Loads

• Pier Design Capacity • 75 kips to 87 kips ultimate • 37 kips to 43 kips allowable • Helical Piers – tension or compression • 52 to 249 kips ultimate • 23 to 131 kips allowable Pier Spacing

• Foundation Strength During Lift • Depends on concrete strength • Steel placement • Dimensions • 7 ft. • Typical for single story – spacing usually dependent on concrete strength • 6 ft. • Typical for two-story – spacing usually dependent on concrete strength Pier Spacing

• Test piers provide very useful information. • Sometimes better than borings. Test Piers

Push Pier Analyses - Installation Pressure La Habra, California Installation Pressure, psi 5000 4500 4000 3500 3000 2500 2000 1500 1000 500 0 0 5 10 15 20 Depth, ft Push Pier Graph 25 30

Allowable tension capacity, pounds Helical Pier Analyses La Habra, California 30000 25000 20000 15000 10000 5000 0 0 5 10 15 Depth, ft Helical Pier Graph 20 25

Push Pier Analyses - Installation Pressure Mission Viejo, California Installation Pressure, psi 6000 5000 4000 3000 pier 13 pier 12 pier 11 2000 1000 0 0 5 10 15 20 Depth, ft Push Pier Graph 25 30

• Injecting grout into loose soils will densify the soils • Denser soils are stronger, less likely to settle • 10% - 20% increase in density is usually the goal. Compaction Grouting

• Compaction Grouting

• Similar to grouting – install material in the ground to displace and densify soils. • Works best in loose fills, with voids • Need to do DCP or other testing to estimate foam quantities. Soil Densification Using Foam

Typical Example Foam Injection

• • Electro-chemical attack on buried metal Some soils are more corrosive than others Usually not an issue if galvanized piers are used Some jurisdictions require a study Corrosion

• To resist lateral loads • Different angles –different combination of lateral and vertical loads Battered Helical Anchors

Lateral Loads

• • Buildings less than 10 years old Hillsides affecting structure More than 2 -story buildings Buildings with irregular footprints Buildings with more than 3 inches differential Buildings with a history of plumbing leaks Properties with post construction engineering reports Buildings that have been part of litigation When Should You Always Call An Engineer?

• Is the recommended scope of repair appropriate? • Are there risks that Eagle. LIFT and the owner would like to know about? • Are you “over-selling” the job? • • “We won’t cause any cracks”. “There will be no further movement”. “Our system is guaranteed”. “All the existing cracks will close up or disappear”. • All estimates should be subject to results of engineering. • An engineer can help you be more clear about potential risks with the client.

• Construction Tolerance • Human Perception • Structural Damage ¼”/20 ft. = 1/960 2”/20 ft. = 1/125 1”/20 ft. = 1/240 Industry Standards Foundation and Slab Tilt

Any Questions? Contact Helfrich-Associates at: steve@helfrich-associaties. com 909 -389 -7316