Walter E. Vanderpool Walter E. Vanderpool Terracon EngineeringTerracon Engineering

A Unique Opportunity to AnalyzeA Unique Opportunity to AnalyzeMicropile Long-Term PerformanceMicropile Long-Term Performance

on a Large Scaleon a Large Scale

PurposesPurposes

•Expand knowledge baseExpand knowledge base•Confirm presumptive theories of micropile Confirm presumptive theories of micropile

performanceperformance• Identify fundamental characteristics of Identify fundamental characteristics of

micropile performancemicropile performance•Correlate soil properties to constructability Correlate soil properties to constructability

and long-term performanceand long-term performance• Identify construction details both beneficial Identify construction details both beneficial

and detrimental to long-term performanceand detrimental to long-term performance• Isolate seismic impactIsolate seismic impact

Available RecordsAvailable Records

•Geotechnical Site ExplorationGeotechnical Site Exploration– Ten 200- to 310-foot boringsTen 200- to 310-foot borings– SPT test dataSPT test data– Index test dataIndex test data– Consolidation test dataConsolidation test data– CPT test dataCPT test data– Pressure meter test dataPressure meter test data

Available Records (continued)Available Records (continued)

•Construction records (eleven 3-ring binders)Construction records (eleven 3-ring binders)– Drill rate by the minute and even secondDrill rate by the minute and even second– Steel mill certificatesSteel mill certificates– Grout materialsGrout materials– Fluid grout propertiesFluid grout properties– Placement records (volume and pressure)Placement records (volume and pressure)– StrengthStrength– Load tests (over 600)Load tests (over 600)

Available Records (continued)Available Records (continued)

• InstrumentationInstrumentation– Over 1200 VW transducers & strain Over 1200 VW transducers & strain

gagesgages– Record length (over 5 years)Record length (over 5 years)– CalibrationsCalibrations– Pre-installationPre-installation– Grout curingGrout curing– Load testingLoad testing

Available Records (continued)Available Records (continued)

•MonitoringMonitoring– Hourly record for over 4 yearsHourly record for over 4 years– Response to earthquakeResponse to earthquake– Load migration to steady stateLoad migration to steady state– Incremental soil-pile load-Incremental soil-pile load-

deformation with depth and timedeformation with depth and time– Incremental soil profile consolidation Incremental soil profile consolidation

by SONDEXby SONDEX

NotesNotes

•System still healthy and operating, but System still healthy and operating, but about to be abandonedabout to be abandoned

•Needs sponsor and funding to sustain Needs sponsor and funding to sustain system beyond original Life-Safety system beyond original Life-Safety purposepurpose

• In-depth analyses needed to understand In-depth analyses needed to understand long-term micropile performancelong-term micropile performance

Specific Research GoalsSpecific Research Goals

1.1. Analyze all load and Analyze all load and movement data so farmovement data so far

2.2. Collect and monitor future load Collect and monitor future load and strain gage dataand strain gage data

3.3. Collect and monitor future Collect and monitor future structural movement datastructural movement data

CommitmentsCommitments

•OwnerOwner •Local AuthorityLocal Authority •ResearcherResearcher •Co-Principal InvestigatorsCo-Principal Investigators •Funds Funds XX