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Report (20) Co GEOPIER Northwest Inc. j pier® "The Alternative to Deep Foundations" July 12, 2010 n . JUL 16 2.010 CIs T I CARD 1)P2cD10--03110 BU TY %W � D6��CSIO OFFICE COPY �r Mr. Mitch Bramlitt 1 `� `(l tC- AutoZone Store Development 123 South Front, Dept 8320 Design Submittal (Revised) Geopier Soil Reinforcement AutoZone Store No. 3756 Tigard, Oregon Dear Mr. Bramlitt: This letter and the attached documents represent our design submittal for Geopier soil reinforcement at the site of the proposed AutoZone retail store in Tigard, Oregon. The following paragraphs document our design of the Geopier reinforcement system for support of spread footings and liquefaction mitigation at the site. Geopier Reinforcement Design Subsurface information as documented in the geotechnical report by Terracon (Project No. 82095068) has been used as a basis for our design. Subsurface conditions generally consist of three to five feet of stiff sandy silt fill, underlain by soft to stiff sandy silt and clayey silt. The silt layer is underlain by loose to very loose, silty sand. Groundwater is present at about 12 feet below grade. Geopier reinforcement has been designed to support spread footing foundations proportioned for a maximum allowable bearing pressure of 4,000 pounds per square foot. We understand that column loads range from 30 to 55 kips and wall loads range from 1.8 to 2.4 kips per lineal foot. The structural support will be provided by installing 20 -inch diameter Geopier displacement elements at the locations shown on the attached Geopier Foundation Plan. All piers will extend to a depth of 30 feet from original grade or to penetration refusal if encountered in dense sand at shallower depths. Geopier reinforcement has been designed to mitigate the potential for liquefaction within the depth of improvement, 30 feet. Our design for liquefaction mitigation addresses two seismic conditions; an earthquake magnitude of 6.8 and peak ground acceleration of 0.27g, and an earthquake magnitude of 9.0 and peak ground acceleration of 0.10g. Based on our analyses a Geopier spacing of about 8 -feet on- centers is required to mitigate site liquefaction under the design earthquake. A grid pattern of Geopier elements is placed throughout the building footprint at about an 8 -foot spacing to mitigate site liquefaction throughout the building area. In addition, a row of Geopier elements is placed outside of the building footprint to protect the perimeter foundation. The soil reinforcement will be installed using the Impact Pier approach. This is a displacement method (does not generate drill spoils) and results in about a 20 -inch diameter element. We estimate that liquefaction induced settlements would be less than 1 -inch under the design earthquakes. Geopier Northwest • 40 lake Bellevue, Suite 100 • Bellevue, WA 98005 • 425/646-2995 • Fax: 425/646 -3118 GE ®PIER Nor Inc. j aclopier "The Alternative to Deep Foundations We understand the building floor slab is designed as a slab on grade. Geopier reinforcement will provide additional settlement control for the building floor slab and support the static floor slab loads. The floor slab section has been designed by Wallace Engineering. We recommend that the slab control joints be aligned with the Geopier elements. Settlement For our analysis, static foundation settlements are first calculated for a zone extending from the bottom of the footing to the depth of pier penetration. The weighted modulus method (Bowles 1988) is used to estimate settlement in the reinforced zone. This method is described in the Geotechnical Engineering Division /ASCE publication "Control of Settlement and Uplift of Structures Using Short Aggregate Piers) by Dr. Evert C. Lawton, Dr. Nathanial Fox, and Dr. Richard L. Handy. A Geopier modulus or stiffness of 125 pounds per cubic inch (pci) was estimated for use in these calculations. The Geopier modulus will be verified by a load test. Additional settlement may occur in the "lower zone" or in the unimproved soil beneath the reinforced zone. The lower zone settlement is calculated using an elastic approach. Based on our analyses, we estimate that total static settlement will be less than 1 inch. Differential static settlement most likely will be less than Y inch. Geopier Installation The Geopier reinforcement will be installed in accordance with the attached Specification for Displacement Rammed Aggregate Pier Soil reinforcement, including a downward load test as outlined in Section 5.02 of the specification. An experienced geotechnical engineer with Geopier Northwest will supervise the installation and conduct the load test. We recommend that Terracon be retained to provide third -party special inspection /monitoring services during installation of the Geopier reinforcement. We appreciate the opportunity to work with you on this project. If you have any questions or require further informa: please call. : ' Sincerely, eopier Northwest Inc. Or ;� #_ I 4 G _ ---• -mes Joh son, P E. ' tV 0� - tom` - O Attachments: Geopier Foundation Plan, Sheet GP0.1- GP1.1 Specifications for Displacement Rammed Aggregate Pier Soil Reinforcement cc: Mr. Brian Metcalfe, Geopier Foundation Company Geopier Northwest • 40 Lake Bellevue, Suite 100 • Bellevue, WA 98005 • 425/646-2995 • Fax: 425/646 -3118 SPECIFICATIONS FOR DISPLACEMENT RAMMED AGGREGATE PIER SOIL REINFORCEMENT PART 1: GENERAL REQUIREMENTS 1.01 Description Work shall consist of designing, furnishing and installing Displacement Rammed Aggregate Pier elements to the lines and grades designated on the project foundation plan and as specified herein. The Displacement Rammed Aggregate Pier elements shall be constructed by driving a displacement mandrel to the design depth and using the rammer head to ram thin lifts of aggregate into the cavity created by the mandrel. The Displacement Rammed Aggregate Pier elements shall be in a columnar -type configuration and shall be used to reinforce soils for support for spread footing foundations. 1.02 Work Included A. Provision of all equipment, material, labor, and supervision to design and install Displacement Rammed Aggregate Pier elements. Design shall rely on subsurface information presented in the project geotechnical report. Layout of Displacement Rammed Aggregate Pier elements, footing excavation, and subgrade preparation following Displacement Rammed Aggregate Pier installation is not included. B. Drawings and General Provisions of the Contract, including General and Supplemental Conditions, and Division 1 Specifications, apply to the work in this specification. 1.03 Approved Installers A. Installers of Displacement Rammed Aggregate Pier Intermediate Foundation Systems shall have a minimum of 5 years of experience with the installation of Rammed Aggregate Pier and shall have completed at least 50 projects. B. Installers shall be licensed by Geopier Foundation Company, Inc. and shall have demonstrated experience in the construction of similar size and types of projects. The Displacement Rammed Aggregate Pier Installer shall be approved by the Owner's Engineer and must be approved two weeks prior to bid opening. The Installer shall adhere to all methods and standards described in this Specification. C. Installers currently approved for these works are: 1. Geopier Northwest, Inc. — Bellevue, WA 1.04 Related Work A. Site Preparation B. Foundations C. Geotechnical Report and Recommendations 1.05 Reference Standards A. Design 1. Lawton, E.C., Fox N.S. and Handy R.L. "Control of Settlement and Uplift of Structures Using Short Aggregate Piers." ASCE. Proceedings of In -Situ Deep Soil Improvement. ASCE National Convention, Atlanta, Georgia. October 9 -13, 1994. 2. Lawton, E.C. and Fox N.S. "Settlement of Structures Supported on Marginal or Inadequate Soils Stiffened with Short Aggregate Piers." ASCE. Geotechnical Special Publication No. 40: Vertical and Horizontal Deformations of Foundations and Embankments, ASCE 2, 962 -974. 3. Fox, N.S. and Cowell M. 1998. Geopier Reference Manual. Published by Geopier Foundation Company, Inc., Scottsdale, AZ. 4. Wissmann, K.J., Lawton E.C. and Farrell T.M. 1999. "Behavior of Geopier - Supported Foundation Systems During Seismic Events." Technical Bulletin No. 1. Geopier Foundation Company, Inc., Scottsdale, AZ. 5. Wissmann, K.J. 1999. "Bearing Capacity of Geopier - Supported Foundation Systems." Technical Bulletin No. 2. Geopier Foundation Company, Inc., Scottsdale, AZ. 6. Wissmann, K.J., Caskey J.M. and FitzPatrick B.T. 2001. "Geopier Uplift Resistance." Technical Bulletin No. 3. Geopier Foundation Company, Inc., Scottsdale, AZ. 7. Wissmann, K.J., FitzPatrick B.T., and Lawton E.C. 2001. "Geopier Lateral Resistance." Technical Bulletin No. 4. Geopier Foundation Company, Inc., Scottsdale, AZ. 8. FitzPatrick, B.T. and Wissmann K.J. 2002. "Geopier Shear Reinforcement for Global Stability and Slope Stability." Technical Bulletin No. 5. Geopier Foundation Company, Inc., Scottsdale, AZ. 9. FitzPatrick, B.T., Wissmann, K.J. and White, D.J. 2003. "Geopier Lateral Resistance" Technical Bulletin No. 6. Geopier Foundation Company, Inc., Blacksburg, VA. 10. Miller, J., FitzPatrick, B.T. and Wissmann, K.J. 2003. "Seismic Site Classification Improvement Using Geopier Soil Reinforcement" Technical Bulletin No. 7. Geopier Foundation Company, Inc., Blacksburg, VA. B. Modulus and Uplift Testing 1. ASTM D -1143 — Pile Load Test Procedures 2. ASTM D -1194 — Spread Footing Load Test C. Materials and Inspection 1. ASTM D -1241 — Aggregate Quality 2. ASTM D -422 — Gradation Soils 1.06 Conflicts in Specifications /References Where specifications and reference documents conflict, the Architect/Engineer shall make the final determination of the applicable document. 1.07 Certifications and Submittals A. The Installer shall submit construction drawings prepared by the Displacement Rammed Aggregate Pier Designer (the Designer) to the Owner or Owner's Engineer for approval at least one week(s) prior to the start of construction. All plans shall be sealed by a Professional Engineer in the State in which the project is constructed. B. The Displacement Rammed Aggregate Pier Designer shall have Errors and Omissions design insurance for the work. The insurance policy should provide a minimum coverage of $2 million per occurrence. C. Modulus test data - The Installer shall furnish the General Contractor a description of the installation equipment, installation records, complete test data, analysis of the test data and recommended design parameter values based on the modulus test results. The report shall be prepared under supervision of a registered professional engineer. D. Daily Displacement Rammed Aggregate Pier Progress Reports — The Installer shall furnish a complete and accurate record of Displacement Rammed Aggregate Pier installation to the General Contractor. The record shall indicate the pier location, length, volume of aggregate used, densification forces during installation, and final elevations or depths of the base and top of piers. The record shall also indicate the type and size of the installation equipment used, and the type of aggregate used. The Installer shall immediately report any unusual conditions encountered during installation to the General Contractor, to the Designer and to the Testing Agency. 1.08 Method of Measurement A. Measurement of the Displacement Rammed Aggregate Pier elements is on a per -pier basis. B. Payment shall cover design and installation of the Displacement Rammed Aggregate Pier Intermediate Foundation system. Excavation of unsuitable materials, drilling obstructions, delays, and remobilization as documented and approved by the Owner or Owner's Engineer shall be paid for under separate pay items. C. Quantities of piers, as shown on plans, may be increased or decreased at the direction of the Owner or Owner's Engineer, based on construction procedures and actual site conditions. PART 2: PRODUCTS 2.01 Materials A. Aggregate used for Displacement Rammed Aggregate Pier construction shall be #57 stone, or shall be other open - graded aggregate with a maximum nominal particle size of 1.5- inches and minimum nominal particle size of 0.5- inches selected by the Installer and successfully used in the modulus test. The aggregate must pass the flow rate tests described in section 4.01 below. B. The General Contractor will provide adequate and suitable marshalling areas on the project site for the use of the Installer for the storage of aggregate and equipment. PART 3: DESIGN REQUIREMENTS 3.01 Displacement Rammed Aggregate Pier Design A. The Displacement Rammed Aggregate Pier elements shall be designed for a Displacement Rammed Aggregate Pier stiffness modulus of 125 pci. The stiffness modulus value shall be verified by the results of the Displacement Rammed Aggregate Pier modulus test, described in this specification, and is based on a 20 -inch constructed diameter. B. The Displacement Rammed Aggregate Pier Intermediate Foundation system shall be designed in accordance with generally- accepted engineering practice and the methods described in Section 1 of these Specifications. The design shall meet the following criteria. Maximum Allowable Bearing Pressure for Displacement Rammed Aggregate Pier Reinforced Soils 4,000 psf C. The design submitted by the Installer shall consider the bearing capacity and settlement of all footings supported by Displacement Rammed Aggregate Piers, and shall be in accordance with acceptable engineering practice and these specifications. Total and differential settlement shall be considered. The design life of the structure shall be 50 years. D. The Displacement Rammed Aggregate Pier system shall be designed to preclude plastic bulging deformations at the top -of —pier design stress. The results of the modulus test shall be used to verify the design assumptions. PART 4: CONSTRUCTION 4.01 Installation of Demonstration Piers and Flow Test The installer shall install a minimum of two initial "demonstration piers" to provide project- specific construction procedures prior to installing production piers. The demonstration pier installation shall be used to determine driving depths, the thickness of the initial bottom lift, and procedures used to place the aggregate. The results of the demonstration program shall be used to establish the site - specific installation criteria for the installation of production piers. If the Two -Step method is used, a Flow Test shall be performed to establish mandrel extraction times. The Flow Test shall be performed as follows: - The mandrel shall be installed to the design depth. A sacrificial or removable tip shall be used at the bottom of the mandrel to facilitate penetration. - The mandrel shall be filled with aggregate. - The mandrel shall be lifted out of the ground quickly and moved so that the aggregate may form a cone - shaped pile on the ground as the aggregate exits the mandrel bottom. - The flow of aggregate through bottom of the tamper head shall be observed and timed. The aggregate flow rate shall be computed where flow rate = volume /time. - The aggregate flow rate observed during the Flow Rate test shall be used by the installer to determine the appropriate mandrel lifting rate during initial aggregate placement. - Hammer impact operations and flow enhancers (compressed air or water) within the mandrel may be used during the flow test, if necessary, to provide a constant, uniform flow of aggregate. If used, the rate of water flow or compressed air pressure shall be noted for implementation during production pier installation. The production piers shall be installed using methods that are consistent with the demonstration pier procedures. The installation of the Demonstration Piers shall be observed and the details recorded by the Installer's Control Technician. 4.02 Installation Procedures A. A sacrificial or removable tip shall be installed at the bottom of the mandrel prior to penetrating the mandrel into the ground. B. The mandrel (and sacrificial tip) shall be pushed to the design depth using crowd force and impact energy. C. Aggregate shall be placed in the cavity. If the sidewalls of the cavity remain stable when the mandrel is lifted, the aggregate may be placed by pouring into the cavity from the ground surface. If the sidewalls of the cavity cave during mandrel extraction, then the first lift of aggregate (to the design installation depth) shall be placed through an opening at the bottom of the mandrel. D. The pier shall be constructed by placing aggregate in lifts that average one foot in compacted thickness. A larger lift may be placed at the bottom of the piers in caving soils provided that this construction technique is verified by the results of the full scale modulus load test. E. Each lift shall be compacted by driving the blunt bottom edge of the mandrel downward using static crowd and vertical dynamic impact energy. F. If a hollow mandrel is used to place the aggregate, the mandrel shall be lifted at a rate no faster than determined from the flow test. G. Subsequent lifts shall be constructed following the same procedure described above until the pier is constructed to the top of pier elevation. H. Alternative lift heights and lowering depth, may be used as appropriate for the project site upon approval by the Designer. At the completion of the pier installation, the hammer shall be turned off and the mandrel pushed downward applying crowd pressure on the top of the pier to provide preloading. 4.03 Densification A. Special high- energy impact densification apparatus shall be employed to densify the Displacement Rammed Aggregate Pier elements during installation. The apparatus shall apply direct vertical impact energy to each constructed lift of aggregate. B. Densification shall be performed using a blunt -ended and beveled (tapered) tamper. The beveled tamper foot is required to adequately increase the lateral earth pressure in the matrix soil during installation. C. Downward crowd pressure shall be constantly applied to the tamper shaft during tamping. 4.04 Plan Location and Elevation of Displacement Rammed Aggregate Pier Elements The center of each pier shall be within six inches of the locations indicated on the plans. Piers installed outside of the above tolerances and deemed not acceptable shall be rebuilt at no additional expense to the Owner, unless mislocated by the General Contractor. 4.05 Rejected Displacement Rammed Aggregate Pier Elements Displacement Rammed Aggregate Pier elements improperly located or installed beyond the maximum allowable tolerances shall be abandoned or reinstalled with new piers, unless the Designer approves other remedial measures. All material and labor required to replace rejected piers shall be provided at no additional cost to the Owner, unless the cause of the rejection is due to an obstruction or mislocation. PART 5: QUALITY CONTROL 5.01 Control Technician The Installer shall have a full -time Control Technician to verify and report all installation procedures. The Installer shall immediately report any unusual conditions encountered during installation to the Design Engineer, the General Contractor, and to the Testing Agency. The quality procedures shall include the preparation of Displacement Rammed Aggregate Pier progress reports completed during each day of installation and containing the following information: A. Footing and Displacement Rammed Aggregate Pier location. B. Volume of aggregate used to form each pier (number of buckets) C. Displacement Rammed Aggregate Pier installation depth. D. Number of lifts. E. Procedure to construct each lift F. Planned and actual Displacement Rammed Aggregate Pier elevations at the top and bottom of the element (based on installation depth). G. Documentation of any unusual conditions encountered. H. Aggregate description. 5.02 Modulus Test A modulus test shall be performed to verify the parameter values selected for design. The modulus tests shall be of the type and installed in a manner specified herein. A. Prior to or after the installation of the modulus test pier, a concrete cap shall be placed over the test pier and embedded at the depth consistent with the bottoms of the footings specified for the structure. B. ASTM D -1143 general test procedures shall be used as a guide to establishing load increments, load increment duration, and load decrements. C. With the exception of the load increment representing approximately 115% of the design maximum top of Displacement Rammed Aggregate Pier stress, all load increments shall be held for a minimum of 15 minutes, a maximum of 1 hour, and until the rate of deflection reduces to 0.01 inch per hour, or less. D. The load increment that represents approximately 115% of the design maximum stress on the Displacement Rammed Aggregate Pier shall be held for a minimum of 15 minutes, a maximum of 4 hours and until the rate of deflection reduces to 0.01 inches per hour or less. E. A seating load equal to 5 percent of the total load shall be applied to the loaded steel plate prior to application of load increments and prior to measurement of deflections to compensate for surficial disturbance. F. Displacement Rammed Aggregate Pier modulus testing shall be performed in accordance with the requirements outlined in the Design Submittal. G. The location of the Displacement Rammed Aggregate Pier modulus test should be coordinated with the project Geotechnical Engineer of record. H. The Displacement Rammed Aggregate Pier shall be installed in a manner that will be consistently used throughout the project. The details of the installation procedure shall be recorded by the Quality Control representative as described above. PART 6: QUALITY ASSURANCE 6.01 Independent Engineering Testing Agency The Owner or General Contractor is responsible for retaining an independent engineering testing firm to provide Quality Assurance services. The Testing Agency should be the Geotechnical Engineer of Record, if possible. 6.02 Responsibilities of Independent Engineering Testing Agency A. The Testing Agency shall monitor the modulus when modulus tests are to be performed. The Installer shall provide and install all dial indicators and other measuring devices. B. The Testing Agency shall monitor the installation of Displacement Rammed Aggregate Pier elements to verify that the production installation practices are similar to those used during the installation of the modulus test elements. C. The Testing Agency shall report any discrepancies to the Installer and General Contractor immediately. PART 7: RESPONSIBILITIES OF GENERAL CONTRACTOR 7.01 Preparation A. The General Contractor shall locate and protect underground and aboveground utilities and other structures from damage during installation of the Displacement Rammed Aggregate Pier elements. B. The General Contractor will provide site access to the Installer, after earthwork in the area has been completed. C. Site subgrade shall be established by the General Contractor within 6 inches of final design subgrade, as approved by the Design Engineer. D. A working surface will be established and maintained by the General Contractor to provide wet weather protection of the subgrade and to provide access for efficient operation of the Displacement Rammed Aggregate Pier installation. 7.02 Layout of the Displacement Rammed Aggregate Pier Elements The General Contractor shall provide layout (construction staking) of the Displacement Rammed Aggregate Pier. The General Contractor shall provide ground elevations in sufficient detail to estimate drilling depth elevations to within 2 inches. 7.03 Displacement Rammed Aggregate Pier Excavation Should any obstruction be encountered during installation for Displacement Rammed Aggregate Pier, the General Contractor shall be responsible for removing such obstruction, or the pier shall be relocated or abandoned. Obstructions include, but are not limited to, boulders, timbers, concrete, bricks, utility lines, etc., that prevent installing the Displacement Rammed Aggregate Piers to the required depth, or cause the Displacement Rammed Aggregate Pier to drift from the required locations. Dense natural rock or weathered rock shall not be deemed obstructions, and piers may be terminated short of design lengths on such materials. If the General Contractor cannot or does not remove such obstructions within one hour from the time the Installer reports the obstruction to the General Contractor, the Installer may remove such obstructions with his own means. Should this occur, the Installer shall receive an extra to the contract to account for their additional expenses, including delay time involved to crew and equipment. 7.04 Utility Excavations The General Contractor shall coordinate all excavations made subsequent to Displacement Rammed Aggregate Pier installations so that at least five feet of horizontal distance remains between the edge of any installed Displacement Rammed Aggregate Pier and the excavation. Protection of completed Displacement Rammed Aggregate Pier elements is the responsibility of the General Contractor. In the event that utility excavations are required at horizontal distances of less than five feet from installed Displacement Rammed Aggregate Piers, the General Contractor shall contact the Displacement Rammed Aggregate Pier Designer to develop construction solutions to minimize impacts on the installed Displacement Rammed Aggregate Piers. Recommended procedures may include: A. Replacing excavated soil with compacted crushed stone in the portions of excavations where the Displacement Rammed Aggregate Pier have been • disturbed. The placement and compaction of the crushed stone shall meet the following requirements. 1. The crushed stone shall meet the gradation specified by the Designer. 2. The crushed stone shall be placed in a controlled manner using motorized impact compaction equipment. 3. The aggregate should be compacted to 95% of the maximum dry density as determined by the modified Proctor method (ASTM D- 1557). 4. The Testing Agency shall be on site to observe placement, compaction, and provide density testing. The test results shall be submitted to the Designer and the General Contractor. The General Contractor shall provide notification to the Testing Agency and the Designer when excavation, placement, and compaction will occur and arrange for construction observation and testing. 7.05 Footing Bottoms A. Structural fill placed between the top of the Displacement Rammed Aggregate Pier elements and the bottom of the footings shall be placed and compacted in accordance with the Project Specifications for structural fill. Observation and testing records by a third -party inspector should be provided to Geopier Foundation Company. B. Excavation and surface compaction of all footings shall be the responsibility of the General Contractor.