Failure Case Study of Construction at a Solid Waste Site K. Madhavan, Ph.D., P.E., Dept. of Civil & Env. Engineering Christian Brothers University Memphis, TN, 38104

Geotechnical Courses Required Courses - CE 322 Geotechnical Engineering - CE 322L Geotech Lab - CE 340 Design of Foundations Elective Course Elective Course - CE 418 Advanced Design of Foundations

Motivation Technical Issues – Brings together all principles & applications including from other required/elective courses Technical Issues – Brings together all principles & applications including from other required/elective courses Opportunities to discuss professional and ethical issues Opportunities to discuss professional and ethical issues Perhaps students understand materials better (connecting concepts with applications) Perhaps students understand materials better (connecting concepts with applications)

Project Data Site was an old sand & gravel dredging area around 1900’s Site was an old sand & gravel dredging area around 1900’s A clay cap was in place A clay cap was in place 23 acre site 23 acre site Four buildings (one & two storey- 140,000 sq. ft.) – on pile foundations Four buildings (one & two storey- 140,000 sq. ft.) – on pile foundations Buildings were on monotube piles Buildings were on monotube piles

Construction at a Landfill Site Geotechnical investigations and report were done in Geotechnical investigations and report were done in Not to build at the site and find another site - The client chose to build at the site (1979) - The cost of construction about $6M - After several years of use, buildings were not usable and were vacated were not usable and were vacated - A remedial work was done for about $10M - Litigation between parties and was settled out of court settled out of court

Construction Details A gas collection system was installed in a sand layer above the waste A gas collection system was installed in a sand layer above the waste Numerous obstructions were encountered while driving the piles Numerous obstructions were encountered while driving the piles Utilities were grade supported Utilities were grade supported Monotube piles were filled with concrete Monotube piles were filled with concrete

Structural Details All buildings had structural floor slabs All buildings had structural floor slabs Floor beams supported by piles and one-way slabs Floor beams supported by piles and one-way slabs Superstructures were of steel frames with exterior metal sheathing Superstructures were of steel frames with exterior metal sheathing

Performance of Buildings, Pavement, and other construction Cracks on floors and walls, floor sloped Cracks on floors and walls, floor sloped Methane gas inflow in buildings Methane gas inflow in buildings Buildings – Differential settlements up to 18 inches Buildings – Differential settlements up to 18 inches Parking area settled as much as 3 ft Parking area settled as much as 3 ft Buried utilities were affected Buried utilities were affected Large amount of asphalt added to pavement Large amount of asphalt added to pavement

Geotechnical Investigations About 100 boreholes About 100 boreholes Soil Layers: Soil Layers: Clay capClay cap Landfill material 30 to 60 ft (materials including car bodies, concrete slabs, etc)Landfill material 30 to 60 ft (materials including car bodies, concrete slabs, etc) Beneath landfill loose sand layer (left from previous dredging operations)Beneath landfill loose sand layer (left from previous dredging operations) Bottom strata (100 ft below)– dense sand – suitable to receive pile foundationsBottom strata (100 ft below)– dense sand – suitable to receive pile foundations

Remediation Use of minipiles to underpin and relevel the buildings Use of minipiles to underpin and relevel the buildings Use of driven piles to support the outside structures (lamp posts, access ramps) Use of driven piles to support the outside structures (lamp posts, access ramps) Use of design-build contract Use of design-build contract Use of best value concept in awarding the contract Use of best value concept in awarding the contract

Analysis of Failure Possible reasons:  Pile Foundation System - Pile installation monitoring - use of proper pile – wall thickness - depth of piles (obstructions) - Negative skin friction (excessive ) - No provision to minimize it - The negative skin friction may have added to the load applied at bearing added to the load applied at bearing

Analysis Cont’d  Gas Collection System - at a landfill site was a poor choice Construction of the gas collection system on grade - water main breaking and washing out part of the sand layer gas collection system

Geotechnical Concepts  Problems in building at landfill sites  Total and differential settlements  Negative skin friction (means of reducing)  Providing proper gas collection system  Construction control & monitoring  Design-build concept  Performance oriented specifications

References ASCE’s Journal of Performance of Constructed Facilities ASCE’s Journal of Performance of Constructed Facilities ASCE’s Journal of Professional Issues in Engineering Education and Practice ASCE’s Journal of Professional Issues in Engineering Education and Practice J. Feld & K.L. Cooper, “Construction Failure,” Second Edition, 1997, John Wiley & Sons. J. Feld & K.L. Cooper, “Construction Failure,” Second Edition, 1997, John Wiley & Sons.

Questions? Comments? Comments?

Installation of Minipiles From the floor surface, holes (7”dia) were drilled through the beams up to the desired depth From the floor surface, holes (7”dia) were drilled through the beams up to the desired depth 4” diameter pipes were inserted 4” diameter pipes were inserted The smaller pipe was twisted and pulled out for a short distance The smaller pipe was twisted and pulled out for a short distance and concrete grout was injected

Installation Cont’d The smaller pipe was withdrawn and high strength steel casing was inserted The smaller pipe was withdrawn and high strength steel casing was inserted For piles at locations other than through the existing monotube piles, 12” diameter monotube pile was driven and similar minipile was constructed For piles at locations other than through the existing monotube piles, 12” diameter monotube pile was driven and similar minipile was constructed

Installation Cont’d After the pile has reached its design strength, the floor was lifted using the pile as a reaction pile After the pile has reached its design strength, the floor was lifted using the pile as a reaction pile The piles were connected to the beams and the original monotube piles were cut off. The piles were connected to the beams and the original monotube piles were cut off.

Pile Testing Four monotube piles were load tested and the ultimate capacity was 150 Tons Four monotube piles were load tested and the ultimate capacity was 150 Tons Two other 12” diameter pipe piles were tested and the ultimate capacity was 200 Tons. Two other 12” diameter pipe piles were tested and the ultimate capacity was 200 Tons.