Location

San Diego, California

Session Start Date

3-26-2001

Session End Date

3-31-2001

Abstract

The 17 January 1994 Northridge Earthquake caused extensive damage to thousands of buildings and condominiums throughout the San Fernando Valley. Not only to the buildings’ structure, but also to the foundations and subdrain systems. This author investigated and documented hundreds of cases where condominium units experienced similar symptoms of damage resulting from collapsed backfill rock and soils from the earthquake forces. A typical condominium building investigated was of three story construction with an 8 to 10 foot high retaining wall on three sides of the 4 to 10 unit building to contain the garages and utility rooms. Some building slabs and other ancillary features, ie. patios, wing walls, decks, steps, walks were constructed directly over the backfill rock and soil. The earthquake shaking especially the vertical acceleration caused the backfill behind the retaining walls to collapse as much as eight inches resulting in failure not only to the retaining walls and surface features, but also to the underlying subdrain pipes behind the building’s retaining wall. Detailed subsurface investigations found in almost every case collapsed backfill rock and cracked, crushed or deformed perforated and solid PVC drain pipes. Other investigations suggested that the crushed pipes were caused by improper installation during original construction. This author conduced lab testing and full scale field testing to demonstrate that the resulting failures were caused by the earthquake shaking and not installation. These failures resulted in millions of dollars in insurance claims and reconstruction of retaining wall backfills and reinstallation of subdrains.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics

Meeting Name

Fourth Conference

Publisher

University of Missouri--Rolla

Publication Date

3-26-2001

Document Version

Final Version

Rights

© 2001 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Mar 26th, 12:00 AM Mar 31st, 12:00 AM

Damage from Collapsed Backfill Rock and Soils Behind Retaining Walls Caused by Earthquake Shaking

San Diego, California

The 17 January 1994 Northridge Earthquake caused extensive damage to thousands of buildings and condominiums throughout the San Fernando Valley. Not only to the buildings’ structure, but also to the foundations and subdrain systems. This author investigated and documented hundreds of cases where condominium units experienced similar symptoms of damage resulting from collapsed backfill rock and soils from the earthquake forces. A typical condominium building investigated was of three story construction with an 8 to 10 foot high retaining wall on three sides of the 4 to 10 unit building to contain the garages and utility rooms. Some building slabs and other ancillary features, ie. patios, wing walls, decks, steps, walks were constructed directly over the backfill rock and soil. The earthquake shaking especially the vertical acceleration caused the backfill behind the retaining walls to collapse as much as eight inches resulting in failure not only to the retaining walls and surface features, but also to the underlying subdrain pipes behind the building’s retaining wall. Detailed subsurface investigations found in almost every case collapsed backfill rock and cracked, crushed or deformed perforated and solid PVC drain pipes. Other investigations suggested that the crushed pipes were caused by improper installation during original construction. This author conduced lab testing and full scale field testing to demonstrate that the resulting failures were caused by the earthquake shaking and not installation. These failures resulted in millions of dollars in insurance claims and reconstruction of retaining wall backfills and reinstallation of subdrains.