411 PILE LOAD TEST

From SHA MediaWiki
Jump to navigation Jump to search
This is not a legal document. Please see disclaimer for more information.
411.01 DESCRIPTION
When a Load Test item is included in the Contract Documents, conduct and record load tests.
411.02 MATERIALS
Not applicable.
411.03 CONSTRUCTION
Ensure that the load test setup, the measuring system, the loading device, the loading procedure, the frequency of measuring the movement of piles, and the record keeping meet D1143, unless otherwise specified.
At each load test location, the Engineer will provide driving criteria for the test pile. Then drive and load test the pile to the test load specified. If the pile fails to achieve this capacity, perform an additional load test on a second test pile. Locate this pile adjacent to the initial test pile and drive it in accordance with the revised driving criteria provided by the Engineer. When directed, redrive piles not meeting the required penetration resistance.
Use the same equipment and methodology for driving the load test piles that will be used for driving the permanent piles.
At each load test location, construct a test enclosure to protect all of the equipment including dial gauges, load cells, loading apparatus, and the personnel taking readings. When necessary, maintain a temperature of at least 50 F within the enclosure. Illuminate the test enclosure to allow taking readings at all times of the day. Ventilate the enclosure to prevent fogging or frosting of gauges.
At least seven days prior to the start of the first pile load test, submit drawings showing all details of the proposed load test setup. Include the method of applying the load, the reaction frame and reaction pile configuration (if used), and the placement and support of measuring devices. Revise the load test setup if directed.
Obtain the services of a professional engineer experienced in structural design and registered in the State of Maryland to design the reaction frame.
Ensure that the load test setup is capable of supporting the test load for the duration of the test.
Maintain a clear distance from reaction piles to the test pile of at least 10 times the distance from the midpoint of web to end of flange for H piles, and at least 10 times the pile top radius for pipe piles and timber piles.
Where necessary or if directed, brace the unsupported length of load test piles to prevent buckling and without influencing the test results.
Use dial gauges having an accuracy of 0.001 in. and a minimum travel of 2 in. as the primary instrument for measuring movement. Place three dial gauges spaced 120 degrees apart as the primary system to measure movement of the top of the pile. Use a scale, mirror, and piano wire as a secondary system.
Ensure that the load apparatus has a capacity of 150 percent of the test load and meets D1143. Ensure that no jack is loaded in excess of 85 percent of the total capacity of the jack. If more than one hydraulic jack is used, provide jacks that are of the same piston diameter, connected to a common manifold and pressure gauge, and operated by a single hydraulic pump.
Apply loads uniformly without impact. If hydraulic jacks are used, equip them with automatic regulators so that constant pressure can be maintained for the duration of the test without frequent manual adjustment.
Unless weights of known magnitude are used to load the test piles, use a load cell having an accuracy tolerance within plus or minus 2 percent of the applied load as the primary method of measuring the test load. Calibrate the load cell prior to the test and submit a copy of the calibration report. Provide a pressure gauge as a secondary system. Calibrate the pressure gauge, hydraulic ram, and hydraulic pump as a unit to an accuracy within 5 percent of the applied load (a single high capacity jack is preferred over multiple jacks). When a multiple jacking system is used, fit each jack with a pressure gauge in addition to the master gauge in order to detect malfunctions.
Recalibrate load measuring devices if required by observed performance.
Cut off the load test pile perpendicular to the longitudinal axis to allow for full bearing. Place a steel plate at least 1 in. thick over the cutoff surface in a manner that facilitates axial loading and even bearing on the test pile.
For all test piles driven to the embedded depths specified, use the standard loading procedure according to D1143 or as directed. Continue loading to the specified test load or to failure, whichever occurs first.
Provide a scale attached to the reaction piles that can be monitored with a transit to determine if the piles are moving.
If at any stage during the test, the Engineer detects malfunctioning of any furnished apparatus, or the load is being eccentrically applied, or the anchor piles are yielding, abandon the test and replace it with another test at no additional cost to the Administration. Ensure that all necessary personnel are present at the site at all times during the performance of the test to maintain the required load.
After the pile test program is complete, remove or cut off reaction piles as specified in 410.03.10.
Perform load tests on steel pipe piles prior to filling.
411.04 MEASUREMENT AND PAYMENT
Load tests will be measured and paid for at the Contract unit price per each for the pertinent Load Test item. The payment will be full compensation for furnishing and installing all equipment, drawings, monitoring, recording, removal of all devices at the completion of the tests, and for all material, labor, equipment, tools, and incidentals necessary to complete the work. In the event that a properly conducted load test fails to achieve the designated capacity, the additional tests will be measured and paid for at the Contract unit price per each under the Load Test item.