1811.3 Driving criteria.
BC § 1811.3
The allowable compressive load on steel and concrete piles, where determined solely by the application of an approved wave equation analyses approved by the engineer, shall not exceed 40 tons (392.3 kN). The allowable compressive loads on timber piles, where determined solely by the wave equation analyses approved by the engineer, shall not exceed 30 tons (294.2 kN). For allowable loads greater than these values, the wave equation method of analysis may be used to establish initial driving criteria, but final driving criteria and the allowable load shall be verified by load tests in accordance with Section 1810.4. Minimum driving resistance and hammer energy may be determined in accordance with Tables 1811.3(a) and 1811.3(b). Table 1811.3(a)Minimum Driving Resistance and Minimum Hammer Energy for Steel H-Piles, Pipe Piles, Precast and Cast-in-Place Concrete Piles and Composite Piles (other than timber) Minimum Driving Resistance a, c, d, ePile Capacity(tons)Hammer Energy b(ft. lbs.)Friction Piles (blows/ft.)Piles Bearing on Soft Rock (Class 1d)(blows/ft.)Piles Bearing on Rock (Class 1a,1b, and 1c)Minimum Driving Resistance a, c, d, ePile Capacity(tons)Hammer Energy b(ft. lbs.)Friction Piles (blows/ft.)Piles Bearing on Soft Rock (Class 1d)(blows/ft.)Piles Bearing on Rock (Class 1a,1b, and 1c)Up to 20 15,00019485 Blows per 1/4 inch(Minimum hammer energy of 15,000 ft. lbs.) 19,000 152724,000 11 16 30 15,000307219,000234024,000 18 26 40 15,000449619,000325324,000 24 34 > 40 AS PER SECTION 1811.3 For SI: 1 foot = 304.8 mm, 1 ton = 907.18 kg. a. Final driving resistance shall be the sum of tabulated values plus resistance exerted by nonbearing materials. The driving resistance of nonbearing materials shall be taken as the resistance experienced by the pile during driving, but which will be dissipated with time and may be approximated as described in Section 1811.3. b. The hammer energy indicated is the rated energy. c. Sustained driving resistance. Where piles are to bear in soft rock, the minimum driving resistance shall be maintained for the last 6 inches, unless a higher sustained driving resistance requirement is established by load test. Where piles are to bear in soil Classes 2 through 5, the minimum driving resistance shall be maintained for the last twelve inches unless load testing demonstrates a requirement for higher sustained driving resistance. No pile needs to be driven to a resistance that penetrates in blows per inch (blows per 25.4 mm) more than twice the resistance indicated in this table, nor beyond the point at which there is no measurable net penetration under the hammer blow. d. The tabulated values assume that the ratio of total weight of pile to weight of striking part of the hammer does not exceed 3.5. If a larger ratio is to be used, or for other conditions for which no values are tabulated, the driving resistance shall be as approved by the commissioner. e. For intermediate values of pile capacity, minimum requirements for driving resistance may be determined by straight line interpolation. Table 1811.3(b)Minimum Driving Resistance and Hammer Energy for Timber Piles Pile Capacity(tons)Minimum Driving Resistance (blows/in.) to be Added to Driving Resistance Exerted by Nonbearing Materials (Notes 1, 3, 4)Hammer Energy(ft./lbs.) (Note 2)Up to 20Formula in Note 4 shall apply 7,500 - 12,000Over 20 to 25 9,000 - 12,00014,000 - 16,000Over 25 to 30 12,000 - 16,000(single-acting hammers)Greater than 30 15,000 - 20,000(double-acting hammers) For SI: 1 ton = 907.18 kg, 1 inch = 25.4 mm. Notes: 1. The driving resistance exerted by nonbearing materials is the resistance experienced by the pile during driving, but which will be dissipated with time and may be approximated as described in Section 1811.3.
2.The hammer energy indicated is the rated energy.
3.Sustained driving resistance. Where piles are to bear in soft rock, the minimum driving resistance shall be maintained for the last 6 inches (152.4 mm), unless a higher sustained driving resistance requirement is established by load test. Where piles are to bear in soil Classes 2 through 5, the minimum driving resistance measured in blows per inch (blows per 25.4 mm) shall be maintained for the last 12 inches unless load testing demonstrates a requirement for higher sustained driving resistance. No pile need be driven to a resistance that penetrates in blows per inch (blows per 25.4 mm) more than twice the resistance indicated in this table nor beyond the point at which there is no measurable net penetration under the hammer blow.
4.The minimum driving resistance shall be determined by the following formula: P=2WhHorP=2E(S + 0.1)(S + 0.1) where: P = Allowable pile load in pounds. Wp = Weight of pile in pounds. Wh = Weight of striking part of hammer in pounds. H = Actual height of fall of striking part of hammer in feet. E = Rated energy delivered by the hammer per blow in foot/lbs. S = Penetration of pile per blow, in inches, after the pile has been driven to a depth where successive blows produce approximately equal net penetration. The value Wp shall not exceed three times Wh .
