1、Standard Method of Test for Permeability of Granular Soils (Constant Head) AASHTO Designation: T 215-14 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1a T 215-1 AASHTO Standard Method of Test for Permeability of
2、Granular Soils (Constant Head) AASHTO Designation: T 215-14 1. SCOPE 1.1. This method describes a procedure for the determination of the permeability of water through granular (cohesionless) soils in a steady-state condition. 1.2. The determination of the coefficient of permeability, k, as defined i
3、n this method, was developed under the assumptions of the validity of Darcys Law, which states that the coefficient of permeability is the ratio of the flow rate to the hydraulic gradient. 1.3. This test procedure is intended for use with disturbed granular soils containing less than 10 percent by m
4、ass of the material passing the 75-m (No. 200) sieve. Soil materials with significant amounts of material smaller than the 75-m (No. 200) sieve are subject to consolidation effects that may influence the outcome of the test results. Permeability of fine-grained and cohesive soils should be performed
5、 by use of a flexible wall permeameter test procedure, such as ASTM D5084. 1.4. Two methods of test, Method A and Method B, are provided. The method used is dependent on the permeameter used to complete testing. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: R 18, Establishing and Implementing a Qua
6、lity Management System for Construction Materials Testing Laboratories R 61, Establishing Requirements for Equipment Calibrations, Standardizations, and Checks T 88, Particle Size Analysis of Soils T 99, Moisture-Density Relations of Soils Using a 2.5-kg (5.5-lb) Rammer and a 305-mm (12-in.) Drop T
7、180, Moisture-Density Relations of Soils Using a 4.54-kg (10-lb) Rammer and a 457-mm (18-in.) Drop T 265, Laboratory Determination of Moisture Content of Soils 2.2. ASTM Standards: D5084, Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible W
8、all Permeameter E1, Standard Specification for ASTM Liquid-in-Glass Thermometers E77, Standard Test Method for Inspection and Verification of Thermometers E563, Standard Practice for Preparation and Use of an Ice-Point Bath as a Reference Temperature 2015 by the American Association of State Highway
9、 and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 215-2 AASHTO E1137, Standard Specification for Industrial Platinum Resistance Thermometers E2251, Standard Specification for Liquid-in-Glass ASTM Thermometers with Low-Hazard Precision Liquids 3.
10、SIGNIFICANCE AND USE 3.1. Soil foundations with inadequate drainage capabilities can result in excess pore water pressures that may ultimately lead to pumping distress. Pumping distress, which is the forceful ejection of waterborne soil subgrade, can occur when freestanding water accumulates between
11、 a pavement surface and the subgrade of concrete pavement. Pumping distress is particularly common on high-volume roadways sustaining heavy axle loads. 4. SUMMARY OF TEST METHOD 4.1. Loose soil material is compacted into a rigid-wall permeameter. A vacuum is applied to the test sample to evacuate ai
12、r from the sample. While remaining under vacuum, the specimen is slowly saturated with water from the bottom upward. Finally, the flow of water is induced through the sample. Once a stable head condition is reached, time, head, and flow measurements are taken and recorded. These measurements are use
13、d to calculate the coefficient of permeability of the soil. It is recommended that measurements be repeated at increasing heads in order to determine the region of laminar flow. 5. APPARATUS 5.1. Apparatus Required for Method A: 5.1.1. PermeameterAs shown in Figure 1 and equipped with the following:
14、 5.1.1.1. Specimen CylinderA rigid glass, plastic, or metal. The diameter of the cylinder required is dependent upon the maximum particle size of the sample to be tested, and shall conform to the minimum requirements described in Table 1. Table 1Minimum Cylinder Diameter Based on Maximum Particle Si
15、ze Minimum Cylinder Diameter Maximum Particle Size Lies Between Sieve Openings Less than 35% of Total Soil Retained on Sieve Opening More than 35% of Total Soil Retained on Sieve Opening 2.00-mm (No. 10) 9.5-mm (3/8in.) 2.00-mm (No. 10) 9.5-mm (3/8in.) 2.00-mm (No. 10) and 9.5-mm (3/8in.) 76 mm (3 i
16、n.) Methods A and B 114 mm (4.5 in.) Methods A and B 9.5-mm (3/8in.) and 19.0-mm (3/4in.) 152 mm (6 in.) Methods A and B 229 mm (9 in.) Methods A and B 5.1.1.2. Porous DisksThe bottom and top of the specimen shall be covered with a porous disk constructed of silicon carbide, aluminum oxide, or simil
17、ar noncorrosive material. The porosity of the disks shall be fine enough to prevent intrusion of soil particles into the pores. The permeability of the disks must be at least one order of magnitude higher than that of the soil to be tested. The disks shall be of sufficient thickness and construction
18、 so that they do not bend, compress, or otherwise deform during regular use. The top porous disk shall be supplied with a suitable spring 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 215-3 AAS
19、HTO or similar device for applying a light pressure of 22 to 45 N (5 to 10 lbf) when the top plate of the permeameter is in place as shown in Figure 1. Note 1The spring, or other suitable device, is used to maintain the density and volume of the soil without significant effects on the saturation and
20、 permeability of the specimen. 5.1.1.3. Manometer TubesWith metric scales, for measuring loss of head across the specimen during testing. The minimum length of the tubes is equivalent to the diameter of the permeameter cylinder. 5.1.1.4. Constant-Head Filter TankSupplied with metric scale on its sid
21、e, for measuring loss of head across the specimen during testing. The minimum length of the tubes is equivalent to the diameter of the permeameter cylinder. 5.1.1.5. Graduated CylinderWith a capacity of 250 mL. Figure 1Constant-Head Permeameter for Use with Method A 5.2. Apparatus Required for Metho
22、d B: 5.2.1. PermeameterAs shown in Figure 2 and equipped with the following: 252015105Manometer OutletsLManometerValveManometer TubesHead,hDPorous Diskor ScreenScreenedManometerGroovePorous Diskor ScreenSoilSpecimenSpecimen CylinderOutlet ValveHeight of SpecimenH2H1SpringOverflowTapWaterValve Top Pl
23、ateInlet ValveFilter Tank ValveConstant-Head Filter Tank (to similar scale)GraduatedCylinderPorousDisk 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 215-4 AASHTO 5.2.1.1. Tailwater ReceptacleA
24、receptacle that is used to maintain a constant tailwater level. The permeameter shall be placed in the tailwater receptacle during testing. When in use, water shall flow from the reservoir tube, through the specimen, out of the bottom drain holes, and into the tailwater receptacle. The rim of the ta
25、ilwater receptacle shall be located above the top of the test specimen by a minimum of 2 in. The receptacle shall have a volume of no less than 5 gal. Note 2A 5-gal bucket, commonly found at hardware supply stores, has been found to be satisfactory for use as a tailwater receptacle. 5.2.1.2. Bubble
26、TubeA rigid glass or plastic tube used to maintain a constant head on the test specimen. The tube shall have an outer diameter of 19 mm. The tube shall be attached to the top of the reservoir with a lock nut and shall have the ability to be adjusted vertically to be able to adjust the gradient used
27、during the test. 5.2.1.3. Reservoir TubeA rigid glass or plastic tube that stores the water used for the test. The reservoir tube shall be 76 mm, 101.6 mm, or 152 mm in diameter depending on the material size as indicated in Table 1 and shall have a graduated scale on its side that indicates the cha
28、nge in water level during test. The top of the reservoir tube shall be supplied with a vacuum line that is used when saturating the specimen and filling the reservoir. 5.2.1.4. Specimen CylinderA rigid plastic or metal tube to contain the test specimen. The specimen tube shall be 76 mm, 101.6 mm, or
29、 152 mm in diameter and 116 mm tall. Refer to Table 1 for minimum cylinder sizes. Note 36-in. metal proctor molds, such as those described in T 99 and T 180, have been found to be satisfactory for use as a specimen cylinder. 5.2.1.5. Filter Papers, Screens, and Perforated Metal PlatesThe bottom and
30、top of the specimen shall be fitted with filter paper, followed by a No. 100 screen, and then a perforated metal plate. The metal plate shall confine the specimen to maintain density and volume of the specimen. The apparatus used shall prevent the movement of soil particles while allowing water to m
31、igrate freely. The filter papers, screens, and metal plates shall have a minimum diameter equal to the diameter of the specimen cylinder being used. The disks and screens shall be of sufficient thickness and construction so that they do not bend, compress, or otherwise deform during regular use. 201
32、5 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 215-5 AASHTO Figure 2Trautwein Permeameter for Use with Method B 5.3. Apparatus Required for Method A and Method B: 5.3.1. Funnel (required only for p
33、reparing samples with a maximum size of 9.5 mm ( 3/8in.) or less)For filling the specimen cylinder. The funnel shall be fitted with a cylindrical spout 13 mm (1/2in.) in diameter for soils with a maximum particle size of 2.00-mm (No. 10 sieve). The funnel shall be fitted with a cylindrical spout 25
34、mm (1 in.) in diameter for soils with a maximum particle size of 9.5-mm (3/8-in. sieve). The spout shall have a length greater than the full length of the specimen cylinder, or a minimum of 150 mm (6 in.), whichever is greater. 5.3.2. Compaction EquipmentShall consist of one of the following, as dee
35、med necessary: 5.3.2.1. Vibrating TamperA vibrating tamper fitted with a tamping foot 51 mm (2 in.) in diameter. 5.3.2.2. Sliding TamperA sliding tamper with a tamping foot 51 mm (2 in.) in diameter and a rod for sliding weight of 0.1 to 1 kg (0.25 to 2.25 lb). A smaller sliding weight shall be used
36、 for sands and a larger sliding weight shall be used for soils with high gravel content. The drop height of the device shall range from 102 to 203 mm (4 to 8 in.). A lower drop height shall be used for sands and a higher drop height shall be used for soils with high gravel content. 5.3.2.3. Other Co
37、mpaction DevicesOther compaction devices may be used to achieve the desired compaction level, provided that they do not cause individual soil particles to break, crumble, or otherwise distort. 5.3.3. ThermometerFor determination of the temperature of the water at the conclusion of the test. The ther
38、mometer shall be one of the following: Bubble TubeWater InletHLSpecimenDrain HolesTailwater ReceptacleFilter Paper,Screen, andMetal PlateFilter Paper,Screen, andMetal PlateSpecimen CylinderReservoir TubeVacuum Line 2015 by the American Association of State Highway and Transportation Officials.All ri
39、ghts reserved. Duplication is a violation of applicable law.TS-1a T 215-6 AASHTO 5.3.3.1. A liquid-in-glass partial immersion thermometer of suitable range with subdivisions and maximum scale error of 0.5C (1.0F) that conforms to the requirements of ASTM E1. Calibrate the thermometer in accordance w
40、ith one of the methods in ASTM E77 or verify its original calibration at the ice point. Note 4ASTM E563 provides instructions on the preparation and use of an ice-point bath as a reference temperature. Note 5If the thermometer does not read 0.0 0.5C (32.0 1.0F) at the ice point, then the thermometer
41、 should be recalibrated. 5.3.3.2. A liquid-in-glass partial immersion thermometer of suitable range with subdivisions and maximum scale error of 0.5C (1.0F) that conforms to the requirements of ASTM E2251. Calibrate the thermometer in accordance with one of the methods in ASTM E77 or verify its orig
42、inal calibration at the ice point (see Notes 4 and 5). 5.3.3.3. A platinum resistance thermometer (PRT) with a probe that conforms to the requirements of ASTM E1137. The PRT shall have a 3- or 4-wire connection configuration and the overall sheath length shall be at least 50 mm (2 in.) greater than
43、the immersion depth. Calibrate the PRT system (probe and readout) in accordance with E644 or verify its original calibration at the ice point (see Notes 4 and 5). Corrections shall be applied to ensure accurate measurements within 0.5C (1.0F). 5.3.3.4. A metal-sheathed thermistor with a sensor subst
44、antially similar in construction to the PRT probe described in Section 5.3.3.3. Calibrate the thermistor system (sensor and readout) in accordance with ASTM E644 or verify its original calibration at the ice point (see Notes 4 and 5). Corrections shall be applied to ensure accurate measurements with
45、in 0.5C (1.0F). 5.3.4. BalanceClass G5 balance meeting the accuracy requirements of M 231. 5.3.5. ScoopWith sufficient capacity to contain approximately 100 g (0.25 lb) of soil. 5.3.6. Timer or ClockReadable to the nearest second. 5.3.7. Length Measuring DeviceSteel rule, calipers, or micrometer for
46、 measuring the dimensions of the specimen cylinder. The length-measuring device must be readable to the nearest 0.1 mm (0.05 in.). 5.3.8. Containers and Mixing PansFor preparation of test specimens. 5.3.9. Vacuum Pump or Water-Faucet AspiratorAttached to the reservoir tube for evacuating air and sat
47、urating testing specimens. 5.3.10. StraightedgeA hardened steel straightedge. 6. CALIBRATIONS, STANDARDIZATIONS, AND CHECKS 6.1. Unless otherwise specified, follow the requirements and intervals for equipment calibrations, standardizations, and checks in R 18. 6.2. Follow the procedures for performi
48、ng equipment calibrations, standardizations, and checks found in R 61. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 215-7 AASHTO 7. SAMPLE PREPARATION 7.1. Select an air-dried, granular, cohes
49、ionless soil having less than 10 percent of its particles finer than the 75-m (No. 200) sieve. The sample shall be obtained by splitting or quartering. 7.2. Perform a particle size analysis in accordance with T 88 prior to permeability testing. Remove any particles larger than 19 mm (3/4in.) from the sample. Determine the mass of these particles and record it as the mass of oversize material. Discard any particles larger than 19 mm (3/4in.) after determining the mass. 7.3. Select a small portion
