Engineering Geology& Seismology Review

for Public Schools & Hospitals in California

Engineering Geology& Seismology Review

for Public Schools & Hospitals in Californiafor Public Schools & Hospitals in California

Centennial of the Quake ’06Centennial of the Quake ’06April 18, 2006 April 18, 2006 —— San FranciscoSan Francisco

Robert H. Sydnor, Robert H. Sydnor, PG 3267, CHG 6, CEG 968PG 3267, CHG 6, CEG 968Member, SSA, EERI, AEG, ASCE, GSA, ASTMMember, SSA, EERI, AEG, ASCE, GSA, ASTM

Senior Engineering GeologistSenior Engineering GeologistCalifornia Geological SurveyCalifornia Geological Survey

California Geological SurveyCalifornia Geological Survey

Geology & Seismology Review for Schools & Hospitals

StateReviewfor CCRTitle 24,

CaliforniaBuilding

Code

California Geological SurveyCalifornia Geological Survey

The Renaissance Building801 “K” Street, 12th Floor

Sacramentowww.conservation.ca.gov/cgs

3 Types of Ground Failure3 Types of Ground Failure

Liquefaction &Seismic Compression

Landslides

Fault Rupture

1906 Damage to Schools1906 Damage to Schools

Four-Story High School in San Jose

CCR Title 24 Reviewsfor Hospitals & Public Schools

are performed by theCalifornia Geological Survey

CCR Title 24 Reviewsfor Hospitals & Public Schools

are performed by theCalifornia Geological Survey

by Certified Engineering Geologistswith support from Senior Seismologists.

C.G.S. works under contract to OSHPD and DSA

California Codes & RegulationsCalifornia Codes & RegulationsCalifornia Codes & RegulationsAlquist-Priolo Earthquake Fault Zoning Act

Public Resources Code §2621 et seq. --- for active faults

California Seismic Hazard Mapping ActPublic Resources Code §2690 et seq. --- for liquefaction & landslides

California Building Standards Administrative CodeCCR Title 24, Part 1 --- specific rules for California agencies

California Building Code, especially Chapters 16, 18, 33CCR Title 24, Part 2 --- derived from IBC and upgraded for California

California Education CodeCCR Title 5, Campuses for Public Schools & Community Colleges

Specific Licensure for Engineering Geologists,Geotechnical Engineers, Structural Engineers, Architects

Business & Professions Code; applies to 3 separate Registration Boards

Calif. Code of Regulations, Title 24Calif. Code of Regulations, Title 24Calif. Code of Regulations, Title 24California Building Standards Administrative Code

CCR Title 24, Part 1 --- specific rules for California agencies

California Building Code, especially Chapters 16, 18, 33CCR Title 24, Part 2 --- derived from IBC and upgraded for California

EERI Monograph SeriesEERI Monograph SeriesEERI Monograph SeriesTwo examples of ten EERI monographs.

Engineering Geology ReferencesAEG volumes – Northern & Southern California

Engineering Geology Engineering Geology ReferencesReferencesAEG volumes AEG volumes –– Northern & Southern Northern & Southern CaliforniaCalifornia

ASCE Standard 7-05ASCE Standard 7ASCE Standard 7--0505

Minimum Design Loads for Buildings &Other Structureswww.asce.org

2006 IBC and2007 CBC will be cross-linked to sections ofASCE Standard 7-05

New Sources of Geologic Information

New Sources of New Sources of Geologic InformationGeologic Information

Latitude & Longitude = easily looked-upAlquist-Priolo Fault Zone Maps = pdfLiquefaction and Landslide Zone Maps = pdfEarthquake Ground Motion attenuation formulasderived from robust new CSMIP datasetCGS Statewide Fault Model – on-line 2002GeoRef & GeoScience World=find geology refsTraining Sessions by EERI & SSA= like this one!

Important PublicationsImportant Publicationsfrom CGS & SCECfrom CGS & SCEC

SP 118SP 118

SP 117SP 117

SCECSCEC

SCECSCEC

GuidelinesGuidelines

ProceduresProcedures

Note 48 ChecklistNote 48 ChecklistNote 48 ChecklistUsed by consulting geotechnical firms to ascertain completenesscompleteness of their engineering geology reports.UniformlyUniformly used by the Engineering Geologistswithin the California Geological Survey.All consulting geotechnical firms are judged to thesame statewide level of scrutinysame statewide level of scrutiny at4 DSA regional offices & two OSHPD offices.Concise 2-page checklist format provides comprehensive overviewcomprehensive overview for the entire process ---- insights for owners/architects for scoping of contract.Citations to specific Code sectionsspecific Code sectionsof CCR Title 24, CBC.

Note 48 ChecklistNote 48 ChecklistNote 48 Checklist

Outline of Note 48Outline of Note 48Outline of Note 48Location of the Campus – latitude & longitude

Engineering Geology–geologic maps, boreholes, cross-sections, active fault trenching, geotech tests, expansive soils, flooding & erosion

Earthquake Ground-Motion, UBE & DBE

Liquefaction & Seismic SettlementLandslidesExceptional & Unusual Geologic HazardsConsultant Review of Grading PlansReport Documentation &Signatures of CEG and RGE

Engineering GeologyNote 48 Checklist

Engineering GeologyEngineering GeologyNote 48 ChecklistNote 48 Checklist

Regional Geology & Regional Fault MapsDetailed Geologic Map of Site, 1 inch ≈100 feetSubsurface Geology & Adequate BoreholesGeologic Cross-Sections, 1 inch ≈20 feetActive Faulting Evaluation; fault trenchingGeologic Hazards Zones – Official SHMA MapsGeotechnical Testing – full suite of lab testsExpansive SoilsType II or Type V portland cementFlooding & Severe Erosion

Geologic Site Investigation —Regional to Site-Specific Mapping

Geologic Site Investigation —Regional to Site-Specific Mapping

Regional Geologic & Fault Maps - 1:250,000Earthquake Epicenter Map - 1:500,000

Geologic Quadrangle Maps, 1:24,000Alquist-Priolo Fault Zone Quads, 1:24,000

Liquefaction & Landslide Zone Maps, 1:24,000Geologic Map of Site, 1 inch ~100 feet

Geologic Cross-Sections 1 inch ~20feetBorehole Logs & Fault Trench Logs

1 inch ~ 5 feet

Grading Plans, 1 inch ~40feet

Public Schools and Hospitals must beSet-Back ≥ 50 feetfrom Active Faults.

CBSAC §4–317e

Fault TrenchingMust be Performedby a CertifiedEngineering Geologist

Holocene-Active FaultsHolocene-Active Faults

AlquistAlquist--Priolo Earthquake Priolo Earthquake Fault Zoning Act of 1972Fault Zoning Act of 1972

References for Active Faults& Fault Trenching Methods

Alquist-PrioloEarthquake Fault Zoning Actlast amended and renamed in 1994

AlquistAlquist--PrioloPrioloEarthquake Fault Zoning ActEarthquake Fault Zoning Actlast amended and renamed in 1994last amended and renamed in 1994

CaliforniaGeological Survey, Special Publication 42,Hart & Bryant,1999 edition,38 pages.SP-42 is posted as.pdf on CGS website.547 quads are zonedfor active faulting.

Hayward Fault ZoneHayward Fault Zone

BART

Hospital

H

Tyson’sLagoon

= school

Hayw

ard

Fault

547 Fault Zone Maps Issued547 Fault Zone Maps Issued

Alquist-PrioloAlquist-PrioloEarthquake Fault Zone MapEarthquake Fault Zone Map

200

Kilometers

1000

5000+5000+Miles of Miles of ActiveActiveFaultsFaultsOfficially Officially ZonedZoned

SeismologyNote 48 Checklist

SeismologySeismologyNote 48 ChecklistNote 48 Checklist

Historic Seismicity - simple EQ map, Map Sheet 49Characterize & Classify the Geologic SubgradeCalifornia Seismic Zone 3 or 4Near-Source Coefficients – if applicable, cap @ Ca=0.66g

Probabilistic Seismic Hazard Analysis, UBE & DBENormalized Spectral AccelerationDeaggregated Seismic Source Parameters

– modal magnitude & fault distanceSeismic Retrofit--Senate Bill 1953 & Division VI-RScaled Time-Histories of EQ Ground-Motion

Classify the Geologic Subgrade

Table 16A-J of Code

Classify the Geologic Classify the Geologic SubgradeSubgrade

Table 16ATable 16A--J of CodeJ of CodeNecessary Step to Choose the Appropriate Attenuation Formula

Type B = RockVs = 760-1500 m/sec

Type C = Soft Rock or Very Dense SoilVs = 360-760 m/secSPT N>50 blow-counts

Type D = Stiff Soil (≈ typical alluvium)Vs = 180-360 m/secSPT N= 15-50 blow-counts

Probabilistic SeismicProbabilistic SeismicHazard MappingHazard Mapping

CGS Map Sheet 48

LiquefactionNote 48 Checklist

LiquefactionLiquefactionNote 48 ChecklistNote 48 Checklist

Geologic Setting for LiquefactionLiquefaction Methodology: Cite & Use:

Youd, Idriss, & 19 others (2001)Seed & 10 others (2003)Martin & Lew (1999) SCEC publication

Liquefaction Calculations, MSF, SF>1.3Seismic Settlement - Entire Soil Column – wet & dryLateral Spreading -- if near cut-slope or riverbankRemedial Options for Liquefaction - list severalAcceptance Criteria for Liquefaction Remediation

California Seismic Hazards California Seismic Hazards Mapping Act of 1990Mapping Act of 1990

California Geological SurveySeismic Zonation MapsLiquefaction & Seismic Settlement

California Geological SurveySeismic Zonation MapsLiquefaction & Seismic Settlement

Evaluate and mitigateliquefaction hazardsat construction sites by:

Avoidance (if possible)during site selection

Liquefaction Analysiswith Calculated Settlements(total and differential, d/L)

Foundation Design orRemediate the Subgrade

Liquefaction Zoning ProcessLiquefaction Zoning Process

Zone

Edg

e

Liquefaction

OFFICIAL ZONE

Holoce

ne Al

luvial

Fan –

soft s

and

“top of t

he Plei

stoce

ne”

Pleisto

cene A

lluvia

l Fan

-

indura

ted

water

50-foot water table

A

A’

LandslidesNote 48 Checklist

LandslidesLandslidesNote 48 ChecklistNote 48 Checklist

Landslide Mapping --- detailedGeologic Subsurface Mapping usingLarge-Diameter BoreholesGeologic Cross-SectionsGeotechnical Strength ParametersLandslide Stability AnalysesLandslide Repair Options

Landslide Books & ManualsLandslide Books & ManualsLandslide Books & ManualsTwo examples of Landslide

monographs

SR-247 Nat. Res. Council SCEC & ASCE book

SLOPE STABILITY ANALYSIS

Static Conditions:FS = R/D = Wcos α tan φ / Wsin α = tan φ / tan α

Dynamic Conditions:ay = (FS - 1)g sin a (Newmark’s Equation)

Wkh(t)W WW

Rs Rd

Ns = W cos α Nd

αDynamicModel

INFINITE SLOPE MODELINFINITE SLOPE MODEL

α

StaticModel

Grading Plan ReviewNote 48 Checklist

Grading Plan ReviewGrading Plan ReviewNote 48 ChecklistNote 48 Checklist

Consulting Geotech Review of PenultimateGrading Plans & Foundation PlansCalled-Inspections for CEG & RGESubdrain Plans & Surface-WaterCut-Fill Prisms & Seismic Compression of FillsDeep Foundations -- piles & caissonsRetaining Walls, Fill Buttresses, Geosynthetics

Report DocumentationNote 48 Checklist

Report DocumentationReport DocumentationNote 48 ChecklistNote 48 Checklist

Geology, Seismology, & Geotechnical References --- concise & pertinent to site

Engineering Geology Reportsigned by Certified Engineering GeologistGeotechnical Engineering Reportsigned by Registered Geotechnical Engineer

Begin with the End in Mind= Subsurface Strategy

Begin with the End in MindBegin with the End in Mind== Subsurface StrategySubsurface Strategy

Work backwards through these Parameters:Ultimate Question: Ultimate Question: What will be the Seismic Settlement?What will be the Seismic Settlement?

Differential Settlement? Total Settlement?Differential Settlement? Total Settlement?Multiple Settlement Calculations — formula of: Tokimatsu & Seed, 1987

Multiple Geologic Cross-Sections — through foundationsAdequate geotechnical lab testing — consolidation tests & void ratiosAdequate subsurface data — frequent sampling in sandsAdequate depth of boreholes �� 50 feet deepAdequate number of boreholes within building footprintVisualize geologic subgrade & anticipate complex

stratigraphy= planning of the drilling program.

Four Modes of SettlementFour Modes of SettlementFour Modes of SettlementUnsaturated Seismic Settlementabove historic-highest water surfaceSaturated Seismic Settlementdue to liquefaction below water tableConsolidation Settlementunder static load of buildingHydrocollapsesoils with high void-ratio,plus anthropic water (lawn watering, etc.)

Basement Excavations

An increasing number of urban Hospitals are using Basements

Sufficiently deep boreholes, >50 ft

Emphasis on lateral stability,seismic settlement, hydrogeology (dewatering), and pile depthsUnderpinning of existing buildingsand city streets (gas, water, sewer)

SB-1953 Seismic Upgrades & Replacement Hospitals

1994 Northridge EarthquakeParking Structure Collapse1994 Northridge EarthquakeParking Structure Collapse

Parking Structures

Sufficiently deep boreholes, ≥50 ft

Emphasis on seismic settlement, particularly differential, ∂ ÷ LDetermine optimum depth tostratigraphic horizon for Pile Tips

3 & 4-Story Reinforced Concrete with Heavy Column Loads

An increasing number ofurban Community Colleges & Hospitalsare planning Parking Structures

Useful Hints to Expedite Your Project

Useful Hints to Expedite Useful Hints to Expedite Your ProjectYour Project

Retain an Engineering Geologist to select a campuswith minimal geologic hazards.minimal geologic hazards.Use longUse long--range planning for adroit site acquisition.range planning for adroit site acquisition.Schools: Do not accept inferior properties from tract Schools: Do not accept inferior properties from tract developers (with: active faults, landslides, developers (with: active faults, landslides, liquefaction).liquefaction).Select aSelect a qualified CEG & RGEqualified CEG & RGE for the design team.Begin geologic field-work in a timely mannertimely manner

(avoid winter drilling & earthwork during rains).(avoid winter drilling & earthwork during rains).Provide preliminary ground-motionto the Structural Engineer in a timely manner.Avoid costly re-design --- one year later.Plan the layout & depth of boreholes commensurate with the subsurface geologic conditions, andcolumn loads and basements.

Practical Hints forEngineering Geology Report Writing

Practical Hints forPractical Hints forEngineering Geology Report WritingEngineering Geology Report Writing

Use Use digital field photographsdigital field photographs to showcase theto showcase thesite geologic conditions and adjacent property.site geologic conditions and adjacent property.Keep abreast of Keep abreast of new publicationsnew publications in seismology, engineering in seismology, engineering geology, & geotech engineering geology, & geotech engineering (SSA, EERI, AEG, ASCE, AGU)(SSA, EERI, AEG, ASCE, AGU)Write Succinctly & Focus on Write Succinctly & Focus on Subsurface Conditions.Subsurface Conditions.Rely on Deep Boreholes & Frequent Samples.Prepare Detailed Geologic Cross-Sections.Always Calculate the Differential Settlement

----- when in alluvial terrain ----- (no estimates)Offer Multiple Strategies for site remediationand seek cost-effective geotechnical solutions.Let the Structural Engineer “solve” the Foundation Design.Use an Executive Summary with Concise FindingsStep-Out Ahead of Code Minimums;Seek to write a Standard-of-Practice report.

Bright Forecast for CaliforniaPublic Schools& Hospitals

Bright Forecast for CaliforniaPublic Schools& Hospitals

Geotechnical Consultants have better access tonew Seismic Hazard Zone Maps, new Metadata & Digital Mappingfor Earthquake Ground-Motion & Geologic HazardsAction Begins with Knowing: Where the Problems AreCCR Title 24, Calif. Bldg. Code = custom code for California hazardsStatewide Uniformity of Reviews usingNote 48 Checklist by the California Geological SurveyResult: Improved Earthquake–Resilient ConstructionWhere it is Needed Most in California