Helical Piles, Tiebacks and Soil Nails · Helical Piles, (12) FSI HA150 Helical Tiebacks and (70)...
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IBSMN-COM-001 ©2014 Foundaon Supportworks®, Inc. All Rights Reserved. Project: Locaon: Date: Challenge: CASE STUDY Commercial Cass Lake Clinic Expansion Cass Lake, MN September 2014 The Cass Lake Clinic expansion consisted of an approximate 25,400 square foot addion to the exisng hospital/clinic building. The project required demolion of an eastern poron of the exisng building and construcon of the addion adjacent to a combinaon of exisng interior and exterior wall lines. Aſter demolion acvies, a 156-foot long wall secon required underpinning to facilitate excavaon below the exisng foongs for construcon of the basement level of the addion. Porons of the exisng foongs required new construcon piles embedded into concrete grade beams and dowelled into the exisng foongs to support new column loading from the addion. An earth retenon system was required along the enre underpinned wall with retained soil heights varying from about 5.7 to 6.5 feet. The retrofit and new construcon piles would resist service loads of 25 and 40 kips, respecvely. The geotechnical invesgaon included four borings advanced to a depth of 20.5 feet and one boring advanced to a depth of 41 feet. The borings indicated a general soil profile consisng of about six to 11 feet of very loose to loose sand fill, medium dense sand to a depth of about 25 feet, dense sand to a depth of about 35 feet, and medium dense sand to the terminaon of the deepest boring at 41 feet. Groundwater was observed at a depth of 34 feet. Soluon: The underpinning was accomplished with a combinaon of retrofit and new construcon helical piles. The 28 retrofit piles consisted of the HP288 (2.875-inch OD by 0.276-inch wall) round shaſt with an 8”-10”-12” helix plate configuraon and a FS288B retrofit bracket with 30-inch external sleeve. The HP288 helical pile capacity was verified with a field compression load test which showed less than 0.16 inch of net pile head movement at the 25 kip service load. The results of the load tesng easily met the failure criteria established for the project which allowed no more than of 0.5 inch of net pile head movement at the service load. The installaon of the test pile/reacon anchors and performance of the compression load test were completed in one day. The eight new construcon helical piles consisted of the HP350 (3.50-inch OD by 0.313-inch wall) round shaſt with a 10”-12”-14” helix plate configuraon. The HP288 and HP350 helical piles were installed to lengths ranging from 14 to 21 feet and to minimum torque correlated ulmate capacies of at least two mes the required service loading (FOS ≥ 2). The 28 retrofit helical piles (HP288) and eight new construcon helical piles (HP350) were installed over a period of three days. Following installaon of the underpinning system, helical ebacks were installed for lateral wall support and helical soil nail/shotcrete walls were constructed for earth retenon below the underpinned wall secons. The installaon of 12 HA150 (1.5-inch solid square bar) helical ebacks and 70 HS150 helical soil nails, and construcon of the shotcrete earth retenon system, were completed in four days. Helical Piles, Tiebacks and Soil Nails Project Summary Structural Engineer: Geotechnical Engineer: General Contractor: Cerfied Installer: Products Installed: EAPC Engineers and Architects Braun Intertec Nor-Son, Inc. Innovative Foundation Supportworks® (8) FSI HP350 Helical Piles, (28) FSI HP288 Helical Piles, (12) FSI HA150 Helical Tiebacks and (70) FSI HS150 Helical Soil Nails Compression load test on HP288 helical pile Installaon of HP288 helical pile Concrete coring for helical eback locaons above new construcon/retrofit helical piles New construcon/retrofit helical piles and ebacks aſter excavaon Completed shotcrete wall secon
Transcript of Helical Piles, Tiebacks and Soil Nails · Helical Piles, (12) FSI HA150 Helical Tiebacks and (70)...
IBSMN-COM-001©2014 Foundation Supportworks®, Inc. All Rights Reserved.
Project: Location:
Date:
Challenge:
CASE STUDY Commercial
Cass Lake Clinic ExpansionCass Lake, MNSeptember 2014
The Cass Lake Clinic expansion consisted of an approximate 25,400 square foot addition to the existing hospital/clinic building. The project required demolition of an eastern portion of the existing building and construction of the addition adjacent to a combination of existing interior and exterior wall lines. After demolition activities, a 156-foot long wall section required underpinning to facilitate excavation below the existing footings for construction of the basement level of the addition. Portions of the existing footings required new construction piles embedded into concrete grade beams and dowelled into the existing footings to support new column loading from the addition. An earth retention system was required along the entire underpinned wall with retained soil heights varying from about 5.7 to 6.5 feet. The retrofit and new construction piles would resist service loads of 25 and 40 kips, respectively. The geotechnical investigation included four borings advanced to a depth of 20.5 feet and one boring advanced to a depth of 41 feet. The borings indicated a general soil profile consisting of about six to 11 feet of very loose to loose sand fill, medium dense sand to a depth of about 25 feet, dense sand to a depth of about 35 feet, and medium dense sand to the termination of the deepest boring at 41 feet. Groundwater was observed at a depth of 34 feet.
Solution:The underpinning was accomplished with a combination of retrofit and new construction helical piles. The 28 retrofit piles consisted of the HP288 (2.875-inch OD by 0.276-inch wall) round shaft with an 8”-10”-12” helix plate configuration and a FS288B retrofit bracket with 30-inch external sleeve. The HP288 helical pile capacity was verified with a field compression load test which showed less than 0.16 inch of net pile head movement at the 25 kip service load. The results of the load testing easily met the failure criteria established for the project which allowed no more than of 0.5 inch of net pile head movement at the service load. The installation of the test pile/reaction anchors and performance of the compression load test were completed in one day. The eight new construction helical piles consisted of the HP350 (3.50-inch OD by 0.313-inch wall) round shaft with a 10”-12”-14” helix plate configuration. The HP288 and HP350 helical piles were installed to lengths ranging from 14 to 21 feet and to minimum torque correlated ultimate capacities of at least two times the required service loading (FOS ≥ 2). The 28 retrofit helical piles (HP288) and eight new construction helical piles (HP350) were installed over a period of three days. Following installation of the underpinning system, helical tiebacks were installed for lateral wall support and helical soil nail/shotcrete walls were constructed for earth retention below the underpinned wall sections. The installation of 12 HA150 (1.5-inch solid square bar) helical tiebacks and 70 HS150 helical soil nails, and construction of the shotcrete earth retention system, were completed in four days.
Helical Piles, Tiebacks and Soil Nails
Project SummaryStructural Engineer:
Geotechnical Engineer: General Contractor:
Certified Installer: Products Installed:
EAPC Engineers and ArchitectsBraun IntertecNor-Son, Inc.Innovative Foundation Supportworks®(8) FSI HP350 Helical Piles, (28) FSI HP288 Helical Piles, (12) FSI HA150 Helical Tiebacks and (70) FSI HS150 Helical Soil Nails
Compression load test on HP288 helical pile
Installation of HP288 helical pile
Concrete coring for helical tieback locations above new construction/retrofit helical piles
New construction/retrofit helical piles and tiebacks after excavation
Completed shotcrete wall section
