The Interface of Foundation Construction with the Urban Environment

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The Interface of Foundation Construction with the
Urban Environment

• Marco D. Boscardin
• 48th Annual Conference of the Northeast
• States Geotechnical Engineers
• October 23-25, 2007
• Boston, MA

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Courtesy Dr. Sauer Corp.
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Typical Considerations for Underground
Construction in an Urban Setting

• Feasible Methods for Site Conditions.
• Costs vs. Budget.
• Schedule.
• Coordination with Other Work.

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Other Key Items to Consider

• Identification of Events that Pose Risk.
• Potential for Such Events to Occurs.
• How Will Occurrences Affect the Project.
• How to Manage/Control Each Risk.
• Who Owns or Can Best Control Each Risk.

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Program Includes Methods and Techniques that are
Options to Address and Manage Risk

• Soil Nails
• Jet Grouting
• CFA Piles
• Instrumentation - Monitoring
• MSES/Geofoam Backfill

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Risk In Underground Construction
Nicholson and Architect of the Capitol
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What is Risk?
The combination of the chance of an event or
hazard and its consequence/ project vulnerability.
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Consequences of Risk
Increased Cost Delays Compromised
Safety Unsatisfactory Performance
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Some GeneralTypes of Risk

• Permitting risks
• Financing risks
• Environmental/Ecological risks
• Legal (government and third party) risks
• Market forces risks
• Labor risks
• Exploration risks
• Design risks
• Construction risks
• Operation and Maintenance risks

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Types of Underground Construction Risks
Physical Contract Design Construction
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Physical Risks
Water Obstructions Nature and Extent Environmental
Conditions Corrosion Material Properties
Magnitude and Consistency
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Contractual Risks
Procurement Type Third Party Impacts Third Party
Agreements Permits Contract Interfaces
Coordination
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Design Risks
Assumptions Third Party Input Parameter
Selection Discipline Interfaces Performance
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Construction Risks
Design vs Construction Design Labor, Materials,
Equipment Weather, Politics, Inflation Understandi
ng of Contract, Specification and Design Intent
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How Much Exploration is Enough?
For Permitting For Design For Budgeting and Cost
Estimating For Construction
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Systematic Risk Managment
Deal with Uncertainties Identify Hazards
Early Assess Vulnerability of Various Project
Approaches Involve the Client ID Client Risk
Tolerance
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Risks should be identified in detail

• Name of each risk
• Type of each risk
• Description of each risk
• Estimate of probability of each risk developing.
• Estimate of the impact/consequences/ severity of
  condition for each risk should it occur (estimate
  cost /delay days).

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• Identify response actions needed to mitigate each
  risk.
• Identify who is in the best position to
  manage/control each risk.
• Identify who will be responsible for each
  particular risk and that particular risks
  management.
• Identify what will trigger each risk and the need
  for response.
• How monitor for each risk and the mitigation of
  each risk.
• Tolerance to each risk.
• Status of each risk.

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Parties With Roles in Risk Management
Client/Owner Project Manager Designer Contractor
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The Client ( with Project Manager)
Deep Dynamic Compaction

• Sets Objectives
• Risk Tolerance?
• Plays Active Role
• Starts the Risk Management Process
• Understands Can Not Eliminate All Risk

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The Designer
Design in Response to Risk ID Hazards ID
Vulnerability Associated with Each Risk Develop
Risk Register Update Risk Register Communicate
Risk Register
Boulders From Slurry Wall
BCEI
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The Contractor

• RM Starts During Bidding
• Owns a Share of the Risk - MM
• Implements RM in Construction
• Updates RR and Feedback to Des and Owner

Soil Nailed Wall
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The Risk Register
What is it? Who is Responsible for it? How is it
Communicated? How is it Updated?
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The Risk Register

• Data Organization
• Routine Procedure
• ID Potential Risks
• ID Pot. Construction Methods
• Match Risks with Methods
• Rank Risks

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Risk Register Cont.

• Decide Action to Deal with each Risk
• ID Phase Risk Affects
• ID How and By Whom each Risk is to be Managed
• Record Actions to Manage Risk

Tiedback Soldier Pile and Lagging Wall
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Risk Register Cont.

• Reassess Each Risk after Action Taken.
• Update Register Regularly
• Communicate Register with Design Team, Owner,
  Contractor, 3rd Party?

Braced Cut for Building
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Risk Analsysis

• ID Risks
• Rank Risks on Prob. Occur/Impact on Project
• Eval. Cost of Risks
• ID how to Reduce Avoid, Manage, Share Risk
• ID Accept. Level of Risk
• ID who acts on and is resp. for each Risk

Mine Subsidence
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Example Occurrence Rating
Probability of Occurrence Rating
Description Improbable 1 Very Rare Not
Likely to Occur Even Once Remote 2 Not
Expected to Occur Even Once Probable 3 Likely
to Occur Once Likely 4 Expected to Occur
More Than Once Frequent 5 Expected to Occur
Often
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Example Vulnerability Rating
Impact Rating Description Very Slight
1 No Delay or Damage Slight
2 Delay up to 2 Days Very
Minor Damage Moderate 3 Up
to1 Week Delay Easily Repairable
Severe 4 1 to 2 Weeks
Delay Significant Repairable
Damage Catastrophic 5 Delays gt 2
Weeks Damage Not Repairable
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Example Risk Tolerance Rating
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Example Risk Register
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Example Risk Register
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Example Risk Register
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Risk Data Sheet
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• A risk register should be developed early in the
  conceptualization of a project and be a living
  document that is updated throughout the life of
  the project as better information is developed
  and risks can be better evaluated or eliminated.

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Managing Risks

• Obtain Sufficient Data
• Select Appropriate Technology
• Assess Technology Sensitivity to Uncertainty
• Monitor Performance
• Have Action Levels
• Have Pre-Planned Response Actions

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Relief Holes Along Post-Tensioned Panels

• Control of ground freeze pressures unique
  application in U.S.

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Appropriate Technology

• Geologic Conditions
• Hydraulic Conditions
• Environmental Conditions
• Site Constraints
• Condition of Adjacent Structures
• Presence of Sensitive Receptors

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10 St. James
Braced Cut for Building
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Vibratory Roller Compactor
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Vibroflotation Ground Modification
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Deep Dynamic Compaction
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Slurry Wall System
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Sensitivity to Uncertainty

• Obstructions
• Natural
• Human-Derived
• Variations in Ground Conditions
• Contamination
• Conditions at Adjacent Structures

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Soil Nailed Wall
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Monitoring Performance

• ID Appropriate Metrics/Observations
• Automated Data Acquistion and Processing
• Quantity of Data
• Correlating Site Status with Measurements
• Setting Action Levels
• Who Collects? (Owner, CM, Designer, Contractor,
  Independent)
• Who Evaluates? (Owner, CM, Designer, Contractor,
  Independent)
• Who Takes Action?

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CLASSIFICATION OF VISIBLE DAMAGE
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Pre-Planned Response

• A form of the Pecks Observational Method.
• Most Probable vs. Most Unfavorable Conditions
  Compatible with Data.
• Identify in Advance, a Course of Action or Design
  Modification for All Foreseeable Significant
  Deviation of the Observations or Measurements
  from Those Predicted on the Basis of the Working
  Hypothesis.

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Building Reinforcement
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Compaction Grouting
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Tiedback Soldier Pile and Lagging Wall
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Underpinning on New Concrete Block
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Wall Underpinning
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Ground Loss During Tunneling Beneath a Road
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QUESTIONS?