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Excav & Deep Foundations Fall 09

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  • Shallow Transfer Load @ Base of Substructure - Not Transferring @ Some Greater Depth Requires Suitable Soil Bearing @ Footing Elev. Column and Wall Footings - Individual or Combination Least Expensive - Minimal Construction Below the Habitable Space Deep Transfer Load @ Far Below the Surface - Sometimes 100’s of Feet Penetrate Unsuitable Soil to Reach Competent Soil or Rock Piles or Caissons - Drive or Drill to Reach Capacity Expensive Compared to Shallow Foundations Extending the Construction Limits to Compensate for Poor Soil @ Substructure
  • Typical Sequence Drilled - Rig and Casing - Large “Crane” with a Drill/Auger Attached (Big Post Hole Digger) Have to Accommodate Drilled Material Bell or Tip Enlargement - Typically 30-45 Degree Permits a “Wider” Distribution of Load Soil must have adequate Cohesion Inspected/Bottom Tested - On Larger - Personnel Lowered into “Hole” Inspect Bell, Test Soil @ Bearing Reinforce Spiral Cage Lowered into the Hole Pour (& Raise Casing) - Tremie- Prevent Segregation Often do Not Require “Cap” - Rather the Column Placed Directly On Top of Caisson
  • Site for caisson installation Note casings
  • Drill rigs
  • Drill rig drilling a caisson hole
  • Auger
  • Auger tip
  • Drill rig set up at a caisson locate & drilling hole
  • Auger removed from hole and excavated earth ‘shaken’ off
  • Casing being lowered
  • Casing lowered into drilled hole
  • Removing water (& mud) from the bottom of the drilled hole
  • Special ‘tip’ to clean the bottom of the drilled hole
  • Inspector getting set to be lowered into the drilled hole to inspect the bottom
  • Inspector examining the bearing surface Note the double casing
  • Reinforcing cage being installed
  • Concrete placement
  • Concrete placement continues as the casing is removed
  • End Bearing - Load Transferred to Tip - Driven till REFUSAL or adequate support - Firm Resistance @ Rock or Dense ‘soil’ Bearing Strata Must Be Reachable Friction - Pile “Side” Frictional Resistance - Bearing Capacity from Frictional Resistance Used - Bearing Strata Too Deep to Reach Driven to Predetermined Depth or Resistance Best in Silt, Clay, & Sandy Soils
  • Materials Wood - Timber - Economical - Capacity 10-35T Draw Backs - No Splices, Decay, Split w/ Driving Steel - H-Piles, Steel Pipe - H-Piles - Mostly for End Bearing, Capacity 30-120T Pro - Displace Little Soil, Convenient Lengths, Splice Con - Corrosion, Can’t Inspect After Driving - Straight? Steel Pipe - Mostly for End Bearing, Capacity 50-150T Closed or Open End Driving Typically Filled with Concrete Closed - Displaces Considerable Soil Concrete - Site Cast, Precast - 60-120T Shapes - SQ, Round, Octagonal, etc. Prestressed or Conventional Reinforcing Adv. - High Load Capacity, No Corrosion, $(Econ.) Displace considerable soil Composites & other Materials
  • Pile tips
  • Cluster of pile driven to desired depth, BUT not yet cut to the correct elevation
  • Pile cluster – driven and cut
  • Load Distribution - Pile Cap - Placed on Pile Clusters Piles Joined by Pile Cap - Reinforced Concrete Cap END OF SEQUENCE
  • Mandrel - tight fitting liner to prevent casing shell from collapsing and then withdrawn Number of Proprietary systems Primary reason to site cast - economy Some proprietary types of sitecast concrete piles. All are cast into steel casings that have been driven into the ground; the uncased piles are made by withdrawing the casing as the concrete is poured, and saving it for subsequent reuse. The numbers refer to the methods of driving that may be used with each: 1. Mandrel driven. 2. Driven from the top of the tube. 3. Driven from the bottom of the tube to avoid buckling it. 4. Jetted. Jetting is accomplished by advancing a high-pressure water nozzle ahead of the pile to wash the soil back alongside the pile to the surface. Jetting has a tendency to disrupt the soil around the pile, so it is not a favored method of driving under most circumstances.
  • Pile cluster – driven and cut
  • Strip footing poured
  • Good to Poor Structural Properties RANGE: ROCK - EXCELLENT PEAT / ORGANIC MAT’L - POOR / UNSTABLE AND UNSUITABLE TO BUILD ON Particle Size BOULDERS - UNSUITABLE / REMOVE - TO - CLAYS - EXTREMELY FINE Drainage / Water Retention COURSE SOILS - BOULDERS GRAVEL, SAND - DRAIN WELL FINE SOILS - SLITS, CLAYS, & ORGANIC - RETAIN WATER Cohesionless to Cohesive COURSE GRAINED SOILS (GRAVEL/SAND) - NO MEASURABLE SHEAR RESISTANCE CLAYS - COHESIVE - MEASURABLE SHEAR RESISTANCE W/O CONFINING FORCES
  • Rarely one type - often a Mixture and/or different “Strata” COMPLICATES THE DESIGN INCREASES THE NEED FOR SUBSURFACE INFORMATION Distribution of soil type and Particle Size Important in Predicting: Load Bearing Capacity Soil Stability RETENTION OF ENGINEERING PROPERTIES UNDER VARYING CONDITIONS; ROCK, GRAVELS, SANDS, & SSOME SILTS - STABLE CLAY (SWELLS & SHINKS W/ WATER) , ORGANIC - POOR Drainage Characteristics Ability to drain - Fdn walls, WHAT IS THE BEST SOIL FOR A CONTRACTOR /Owner TO BUILD ON? DEPENDS: ROCK - STABLE BUT DIFFICULT TO REMOVE SAND/GRAVEL - DRAINS WEEL BUT NOT COHESIVE W/ SOME CLAY - COHESIVE, BUT OFTEN DRAINS POORLY
  • Common on projects with high loadings Bearing Capacity - # Blows/Unit (ft) Soil Strata & Water Table Data NEEDED FOR DESIGN, ESTIMATION, CONSTR. Loads transmitted deep into soil Soil Samples PARTICLE SIZE LIQUID LIMIT (water content - plastic to liquid state) PLASTIC LIMIT (H2O content; plastic to solid state) WATER CONTENT SHRINKAGE SHEAR AND COMPRESSIVE STRENGTH Expected consolidation and Rate (under load) Sample Holes Strategically Located WHY? Information used to prepare Soils Report PROVIDED TO DESIGNER & CONTRACTOR SOIL INFORMATION & WATER TABLE RECOMMENDS: SUITABLE FDN TYPES DEPTHS & BEARING CAPACITIES EXPECTED SETTLEMENT RATES BENEFIT TO DESIGNERS??? PROVIDES NECESSARY DESIGN INFORMATION BENEFIT TO CONTRACTOR??? EXCAVATION & BACKFILL METHOD, SOIL RETENTION SYSTEM, FORM AGAINST SOIL?, H2O TABLE LOCATION ALSO - BASIS FOR EXTRA IF ACTUAL CONDITIONS DIFFER!
  • Unit of Measure (Estimating & Mgm’t)) Excavation & Backfill Cubic Yards (CY) Grading Sq. Ft. or Sq. Yd. Productivity Issues Type of Operation (Mass or Ltd./Confined) LARGE QUANTITY?, OPEN SPACE, ETC. Type of Material (Soil) ROCK VS CLAY SAND VS ROCK Material Transportation EXPORT / IMPORT DISTANCE DISTANCE TO MOVE AROUND ON SITE Expected Environmental Conditions Weather WINTER, SPRING, ETC.? WET, DRY, ETC.? Economy Labor availability, etc.
  • Unrestricted Site “ ROOM” ON THE SITE Restricted Site MIMIMAL ROOM NEXT TO A BUILDING OR STRUCTURE OR STREET, ETC.
  • Bench and/or Angle of Repose “ NATURAL SLOPE” Steeper for cohesive soils Must have perimeter clearance Considerations Water Diversion SITE WATER - DIVERT OR COLLECT OFTEN - TOP AND BOTTOM Bank Erosion PROTECT BANK - VISQUEEN, TARPS, ETC. Safety WORKMAN BELOW - PROTECT AGAINST BANK COLLAPSE Storage of Backfill NEEDED TO BACKFILL AGAINST STRUCTURE Most likely - least expensive
  • Soldier Beams and Lagging Sheet Piling DRIVE PRIOR TO EXCAVATION Slurry LAYOUT WALL DIG WITH CLAMSHELL, FILL W/ SLURRY BULKHEADS, REINF. & POUR
  • Sequence PRIOR TO EXCAVATION- DRIVE H-PILES (SPACED) EXCAVATE & INSTALL LAGGING BACKFILL - REMOVE LAGGING REMOVE H-PILES COMMON - EASE & COST MUST HAVE ROOM TO INSTALL FOUNDATIONS
  • Wood, Steel OR Precast DRIVE PRIOR TO EXCAVATION PULL (OR LEAVE) - (WOOD WOULD NOT LEAVE) - IF LEFT MAY BE OBSTRUCTION TO UTILITIES , IF POUR AGAINST – MAY be a PROBLEM W/ WATERPROOFING AND EXTERIOR FDN DRAINAGE DRIVING MAY CAUSE DAMAGE TO SURROUNDING STRUCTURES
  • Steps in constructing a slurry wall. (a) The concrete guide walls have been installed, and the clamshell bucket begins excavating the trench through a bentonite clay slurry. (b) The trench is dug to the desired depth, with the slurry serving to prevent collapse of the walls of the trench. (c) A welded cage of steel reinforcing bars is lowered into the slurry. (d) The trench is concreted from the bottom up with the aid of a tremie. The displaced slurry is pumped from the trench, filtered, and stored for reuse. (e) The reinforced concrete wall is fled back as excavation progresses.
  • Provide Temporary Bank Support DON’T HAVE ROOM TO LAY BACK RESTRICTED SITE - EX; DOWNTOWN SHEETING (SOME TYPE) Unbraced - Cantilevered NO BRACING REQUIRED - CANTILEVERED DRIVEN INTO GROUND Braced Crosslot Bracing Rackers and Heel Blocks Tiebacks DISCUSS ADVANTAGES / DISADVANTAGES Crosslot Bracing SIDE TO SIDE - INTERFERES WITH EXCAVATION AND “FOUNDATIONS”? Rackers and Heel Blocks LESS COSTLY, BUT STILL INTERFERES Tiebacks - EXPLAIN; DRILL, TENDONS, GROUT, CURE, STRESS
  • Pump(s) Placed in “Low” points ELECTRIC, GAS, DIESEL SUCTION HOSE AND DISCHARGE LINE Requires clearance around excavation Most Common Often - Least expensive SUMP PUMPS AS SOIL BECOMES MORE PORUS, AND WATER TABLE RELATIVELY HIGHER (HIGHER VOLUME OF WATER) LESS OF AN OPTION
  • Superstructure ABOVE GROUND Substructure BELOW GROUND - HABITABLE Foundation
  • QUAKE ZONES ALLOW THE GROUND TO MOVE LATERALLY w/o damaging the building ISOLATORS ACT AS A PARALLELOGRAM - KEEPING BUILDING LEVEL
  • Reasons It May Be Required Failure of the Existing Foundation Often Settlement Change in Building Use EX. - Install Heavy Equipment New Construction Adjacent to an Existing Blg. - COMMON
  • Enlarge Existing Foundation Increase Bearing Area Install a New Foundation - Footing, Piles, Caissons Stabilize Surrounding Soil - Grout, Chemical Stabilization, Mud Jacking Problems Can be Dangerous to Workman & Occupants - Often - Must Provide Temporary Support - Jack to Relieve Loads, Support while Constructing Existing Utilities and Other Obstructions - Invariably In the Area Limited Working Space - Slow, Expensive, Difficult, Specialized - Specialty contractors with the Required Equipment for Difficult Projects Liability - During and After Construction
  • Sheets - Plastic, asphaltic, synthetic rubber GENERALY APPIED TO THE OUTSIDE - H20 PRESSURE DISADVANTAGE - COVERED, LEAK INSPECTION? Coatings (asphaltic) GENERALY APPIED TO THE OUTSIDE - H20 PRESSURE DISADVANTAGE - COVERED, LEAK INSPECTION? SPRAYED, BRUSHED, ROLLED Cementitious Plasters APLIED INSIDE OR OUTSIDE - OFTEN INSIDE - CAN SEE DISADVANTAGE - BRITTLE / CAN CRACK Bentonite clay GENERALY APPIED TO THE OUTSIDE - H20 PRESSURE DISADVANTAGE - COVERED, LEAK INSPECTION? BEST / MOST EXPENSIVE SWELLS TO SEVERAL TIMES ITS DRY VOLUME Protection Board APPLIED TO COATING PRIOR TO COVERING FIBER, ASPHALT, ETC Waterstop PLACED AT JOINTS –Where MOVEMENT POSSIBLE SYNTHETIC RUBBER, EXPANSIVE CLAY, ASPHALTIC
  • Waterproofing w/ protection board & Stone
  • Drainage Matt
  • Spread Footing
  • Strip Footing Excavated & reinforced

Excav & Deep Foundations Fall 09 Excav & Deep Foundations Fall 09 Document Transcript

  • Foundations & Excavation Leaning Tower of Pisa Professor Richard Luxenburg, AIA
  • Foundations
    • Purpose;
      • Transfer Building Loads to the Earth
    • Basic Types
      • Shallow: Transfer Load @ Base of Substructure
      • Deep: Penetrate Unsuitable Soil to Reach Competent Soil or Rock
  • Deep Foundations - Purpose transfer building loads deep into the earth
    • Basic types
      • Drilled (& poured)
      • Driven
  • Caissons
    • Similar to a column footing - only deep
    • Drilled to required bearing capacity
    • Point bearing (exception - socketed)
  • Caisson Installation Sequence
    • Hole drilled with a large drill rig
    • Casing installed (typically)
    • Bell or Tip enlargement (optional)
    • Bottom inspected and tested
    • Reinforced
    • Concrete placement (& casing removal)
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  • casing being removed
  • Driven Piles
    • Two basic types of Piles
      • End bearing pile - point loading
      • Friction pile - load transferred by friction resistance between the pile and the earth
  • Pile material
    • Steel; H- piles, Steel pipe
    • Concrete; Site cast or Precast
    • Wood; Timber
    • Composite
  • Pile Driver
    • Massive Rig - Crane w/Leads (Guide Rails)
    • Logistics and Sequence Considerations (Level Site)
    • Noise , Vibration
    • Single Acting - Lift and Drop
    • Double Acting - Steam, Compressed Air or Hydraulics, Diesel
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  • Pile Caps
  • Site Cast Concrete Piles Cased Piles Uncased Piles
  • Deep Foundations
    • Units of Measure
      • Drilling & Driving
        • #, Lineal foot, & Size
    • Major Productivity Issues
      • Type of Material (Soil)
      • Material & Equipment Access
      • Quantity (Total & # per cap/cluster)
  • Differential Settlement
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  • shallow foundation with perimeter spread footing
  • Soils What Architects & Engineers look for:
    • Structural Properties
    • Particle Size
    • Drainage / Water Retention
    • Cohesiveness
  • Clays Porous (sandy)
  • Soil Distribution
    • Rarely one type - often a Mixture and/or Different Strata
    • Distribution of soil type and Particle Size Important in Predicting:
      • Load Bearing Capacity
      • Soil Stability
      • Drainage Characteristics
  • Loadbearing Capacity
  • Soil Borings / Penetration Tests
    • Common on projects with high loadings
    • Bearing Capacity - # Blows/Unit (ft)
    • Soil Strata & Water Table Data
    • Soil Samples & Testing
    • Sample Holes Strategically Located
    • Information used to prepare Soils Report
  • Foundation Design & Building Codes
    • Sample IBC Provisions
      • Maximum loadbearing values for soil types
      • Design criteria
      • Soil investigation & testing requirements
      • Minimum foundation dimensions
    • Purpose: to ensure an adequate building foundation system.
  • Test boring equipment
  • Rocks & Soil
    • Rocks
      • Mineral particles are firmly bonded together
      • Located beneath layer(s) of soil
    • Soil
      • Unconsolidated mineral particles or conglomerates located at the top layer of the earth’s crust
      • Most foundations are supported on soil, except when the soil strength is not adequate
  • Soil classification
    • Particle size
      • Coarse grained (gravel & sand)
      • Fine grained (silt & clay)
    • Particle shape
      • Spherical or ellipsoidal, shaped by mechanical weathering
        • Gravel, sand & silt
      • Flat, plate-like, large surface area to volume ratio
        • Behavior influenced by electrostatic forces and presence of water
    • Cohesion
      • Cohesive soils are fine grained and particles are attracted to each other in the presence of water.
      • Non-cohesive soils are course grained and are not attracted to each other
    • Organic soils consist of fully or partially decayed plant matter, compressive and unsuitable for foundations
  • Soil characteristics by particle size
  • Soil properties & Foundation design
    • Engineering properties
      • Soil bearing capacity
    • Particle size distribution
      • Stability & drainage
    • Nature of excavation
    • Depth of water table
      • Drainage and dewatering
    • Compressivity
      • Foundation settlement
  • Soil sampling and testing
    • Soil sampling
      • Test pit method
      • Test boring method
        • Also allows for standard penetration test on site
    • Laboratory testing
      • Sieve analysis
        • Determines particle size distribution
        • Soil classification
      • Moisture content
      • Dry density
      • Liquid limit, plastic limit
      • Compressive strength
      • Shear strength
  • Test boring log
  • Earthwork
    • Units of Measure
      • Excavation & Backfill Cubic Yards (CY)
      • Grading Sq. Ft. or Sq. Yd.
    • Major Productivity Issues
      • Type of Operation (Mass to Ltd./Confined))
      • Type of Material (Soil)
      • Material Transportation
      • Expected Environmental Conditions
  • Slope Support Deep Excavations
    • Types of Site Conditions
      • Unrestricted Site – area sufficiently larger that the building footprint
      • Restricted Site – area constricted / limited
  • Unrestricted Site
    • Bench and/or Angle of Repose
    • Must have perimeter clearance
    • Considerations
      • Bank Erosion
      • Water Diversion
      • Safety
      • Storage of Backfill (& cost)
    • Most likely - least expensive
  • Sloped Excavation @ the ‘Angle of Repose’
  • Benched Excavation
  • Excavation in Clay (A Cohesive Soil)
  • Restricted Site
    • Types of Sheeting
    • Soldier Beams and Lagging
    • Sheet Piling
      • Wood
      • Steel
      • Precast
    • Slurry Wall
  • Supports for deep excavations
    • Sheet piles
      • Interlocking vertical steel sheets driven into soil prior to excavation
      • Lower part of sheet remains buried, providing cantilever
      • Deep excavations braced (> 15 ft.)
    • Bracing
      • Cross-bracing
      • Diagonal bracing
      • Tieback
  • Profile of steel sheet piles
  • Sheet piles driven into soil with diesel hammer
  • Drilling for tiebacks
  • Close-up: drilling for tiebacks
  • Tieback hole
  • Tendon as tieback
  • Connection of lagging to soldier piles
  • Plan: contiguous bored piles
  • Contiguous bored piles support deep urban excavation
  • Secant piles
  • Reinforced concrete wall using bentonite slurry
  • Section: soil nailed excavation support
  • View of soil nailed excavation
  • Solder Beam & Lagging
  • with tiebacks
  • Sheet Pile Options
  • Steel Sheeting
  • Steel Sheeting Interlock
  • Slurry Wall
    • Steps
      • Layout
      • Excavate the soil
      • Interject Slurry to
      • prevent Collapse as
      • Excavation Continues
      • Install Reinforcing
      • Place Concrete
      • (replaces the slurry mix)
  • Restricted Site
    • Sheeting Support
      • Unbraced - Cantilevered
      • Braced
        • Crosslot Bracing
        • Rackers and Heel Blocks
        • Tiebacks
  • Bracing
    • Crosslot
    • Rackers
    • Tiebacks
  • Crosslot Bracing
  • Tieback Installation
    • Rotary Drill Hole
    • Insert & Grout Tendons
    • Tendons Stressed & Anchored
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  • Dewatering
    • A process of removing Water and/or lowering the Water Table within a construction site
    • Purpose: To Provide a Dry working platform - (typically required by Code and Specification)
    • If the Water Table is above the working platform;
      • Options:
        • Keep water out
        • Let water in & remove it
        • Combination
  • Sump Pumps
    • Sump Pump Considerations
      • Pump(s) Placed in Low points
      • Water collected & Pumped Out
      • Requires clearance around excavation
      • Most Common
      • Often - Least expensive
  • Well Points
    • Keeping water out of the excavation by
    • Lowering the water table
  • Suction Pumps Discharge Line Well Point Header Pipe
  • Watertight Barrier Walls
    • Keep Water Out
    • Barrier must reach an impervious strata
    • Types
      • Slurry Walls
      • Sheeting w/ pumps
    • Must resist hydrostatic pressure
  • Major Building Parts
    • Superstructure
    • Substructure
    • Foundation
  • Seismic Base Isolation
  • Underpinning
    • a process of strengthening and/or stabilizing the foundation of an existing building
    • Reasons it may be required
      • Failure of existing foundation
      • Change in building use
      • New construction adjacent to existing
  • Underpinning Methods and Problems
    • Methods
      • Enlarge existing foundation
      • Install a new foundation
      • Stabilize surrounding soil
    • Problems/Concerns
      • Dangerous
      • Temporary support and existing conditions
      • Limited work space, slow process, expensive
  • Retaining walls Design Elements to Prevent Failure
    • Relieve H2O pressure
      • Crushed stone
      • Weeps
    • Overturning
      • Cantilevered Footing
      • Reinforcing
    • Sliding
      • Key
  • Waterproofing
    • Two basic approaches to Waterproofing
      • Waterproof Membranes, or
      • Drainage
      • Generally - both used in tandem
  • Waterproofing Membranes
    • Materials
      • Liquid or Sheet (Plastic, asphaltic, synthetic rubber)
      • Coatings (asphaltic)
      • Cementitious Plasters & admixtures
      • Bentonite clay
    • Accessories
      • Protection Board
      • Waterstop
    • Unit of Measure - SF, Mils (thickness)
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  • Dampproofing Typically, a liquid asphalt applied with a roller or sprayer Not an effective barrier for water under pressure. BUT, will prevent ground ‘ moisture’ from migrating through a wall. Typically used in conjunction will drainage pipe.
  • Site preparation prior to construction
    • Fencing site
    • Locate and mark utility lines
    • Demolish unneeded structures and utility lines
    • Remove trees, brush, topsoil
  • Excavation
    • The process of removing soil or rock from its original location in preparation for construction
    • Depth of excavation depends on
      • Foundation type (deep or shallow)
      • Soil type
    • Types of excavations
      • Open. Large and sometimes deep excavations
      • Trenches. Linear excavations for utilities or footings
      • Pits. Excavations for footing of one column, elevator shaft, etc.
  • Controlling groundwater
    • Prevent surface water from entering excavation
    • Draining soil around the foundation
      • Sumps
      • Well points
  • Sumps collect and pumps discharge groundwater after it enters the excavation
  • Wellpont system prevents water from entering excavation
  • Footing types
  • Presumptive allowable bearing capacity of soils Class of Material Allowable bearing capacity Crystalline bedrock 12.0 ksf Sedimentary and foliated rock 4.0 ksf Soil types GW and GP 3.0 ksf Soil types SW, SP, SM, SC, GM, & GC 2.0 ksf Soil types CL, ML, MH, and CH 1.5 ksf
  • Commonly used deep foundations
  • Grade beam and drilled piers
  • Formwork: Grade beam and drilled piers
  • Grade beam and drilled piers
  • Wood light frame on grade beam and drilled piers
  • Structural slab on drilled pier, note void boxes below slab
  • Grade beams and under slab utilities in place
  • Void boxes being placed prior to constructing structural slab
  • Interior of structural slab on ground supported on pier caps
  • Below grade waterproofing
    • Prevent water from reaching foundation
      • Direct surface run-off away from building
    • Waterproof below grade structure
      • Apply waterproof layer
      • Incorporate a foundation drainage system
  • Waterproofing layer
    • Applied to outside surface of
      • basement wall
      • basement floor
    • Cold systems most commonly used today
      • Rubberized asphalt or thermoplastic sheets
        • 60 mil thick, self-adhering rolls
      • Liquid applied elastomeric compounds
        • Sprayed on or rolled
  • Drainage system
    • Purpose of system is to collect, drain and discharge subsoil water away from building
    • System includes
      • Drainage mats
        • Placed against the waterproofing or insulation layer
        • Open structure allows water to drain downward
        • Reduce or eliminate water pressure on below grade wall
        • Protect waterproofing
      • Foundation drain pipe sloped to carry water away from foundation to storm drain or sump pit
        • 4 in to 6 in perforated pipe at base of foundation
        • Laid in bed of crushed rock
        • Protected by filter fabric that prevents clogging from soil
  • Typical foundation waterproofing and drainage system for subgrade wall
  • Positive-side, negative-side and blind-side waterproofing
    • Positive-side added to exterior wall
      • Most effective and commonly used
      • Protects wall against water seepage, mold growth, corrosion
      • Backfilled after completion
    • Negative-side applied to interior side of wall
      • Used in remedial applications, not as effective as other options
    • Blind-side is applied to the outside of a wall that becomes inaccessible after construction
      • Structural wall placed directly against excavation support system that acts as formwork.
      • Applied directly to excavation support system
  • Blind-side waterproofing
  • Constructing a basement foundation using blind-side waterproofing
  • Reinforcement placed in preparation for interior formwork.
  • Symbols used is USCS
    • G Gravel
    • S Sand
    • M Silt
    • C Clay
    • Pt Peat
    • O Organic
    • W Well-graded
    • P Poorly-graded
    • L Low plasticity
    • H High plasticity
  • Increasing moisture content in fine-grained soil
  • Definitions
    • Plastic limit (PL)- moisture content at which soil becomes plastic (putty-like)
    • Liquid limit (LL)- moisture content at which soil becomes liquid (slurry)
    • Plasticity index (PI) - difference between Liquid limit and Plastic limit
      • LL - PL = PI
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  • Combination Spread & Strip Footing