Designation: d 2434 – 68 (Reapproved 2006) Standard Test Method for Permeability of Granular Soils
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- 4. Apparatus
| 3. Fundamental Test Conditions
3.1 The following ideal test conditions are prerequisites for the laminar flow of water through granular soils under constant-head conditions: 3.1.1 Continuity of flow with no soil volume change during a test, 3.1.2 Flow with the soil voids saturated with water and no air bubbles in the soil voids, 3.1.3 Flow in the steady state with no changes in hydraulic gradient, and 3.1.4 Direct proportionality of velocity of flow with hydrau- lic gradients below certain values, at which turbulent flow starts. 3.2 All other types of flow involving partial saturation of soil voids, turbulent flow, and unsteady state of flow are transient in character and yield variable and time-dependent coefficients of permeability; therefore, they require special test conditions and procedures. 4. Apparatus 4.1 Permeameters, as shown in Fig. 1 , shall have specimen cylinders with minimum diameters approximately 8 or 12 times the maximum particle size in accordance with Table 1 . The permeameter should be fitted with: ( 1) a porous disk or suitable reinforced screen at the bottom with a permeability greater than that of the soil specimen, but with openings suffıciently small (not larger than 10 % finer size) to prevent movement of particles; (2) manometer outlets for measuring the loss of head, h, over a length, l, equivalent to at least the diameter of the cylinder; (3) a porous disk or suitable reinforced screen with a spring attached to the top, or any other device, for applying a light spring pressure of 22 to 45-N (5 to 10-lbf) total load, when the top plate is attached in place. This will hold the placement density and volume of soil without significant change during the saturation of the specimen and the permeability testing to satisfy the requirement prescribed in 3.1.1 . 4.2 Constant-Head Filter Tank, as shown in Fig. 1 , to supply water and to remove most of the air from tap water, fitted with suitable control valves to maintain conditions described in 3.1.2 . N OTE 1—De-aired water may be used if preferred. 1 This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.04 on Hydrologic Properties and Hydraulic Barriers. Current edition approved Feb. 1, 2006. Published March 2006. Originally approved in 1965. Last previous edition approved in 2000 as D 2434–68(2000). 2 For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. 1 Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States. http://qstandard.org/ 4.3 Large Funnels, fitted with special cylindrical spouts 25 mm (1 in.) in diameter for 9.5-mm ( 3 ⁄ 8 -in.) maximum size tải về 126.61 Kb. Chia sẻ với bạn bè của bạn:
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