《BS-6906-7-1990.pdf》由会员分享，可在线阅读，更多相关《BS-6906-7-1990.pdf（14页珍藏版）》请在三一文库上搜索。
1、BRITISH STANDARD BS 6906-7: 1990 Methods of test for Geotextiles Part 7: Determination of in-plane waterflow Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 12:57:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6906-7:1990 This British Standard, having been prepared under the direction of th
2、e Textiles and Clothing Standards Policy Committee, was published under the authority of the Board of BSI and comes into effect on 31 December 1990 BSI 02-1999 The following BSI references relate to the work on this standard: Committee reference TCM/35 Draft for comment 89/39362 DC ISBN 0 580 18702
3、0 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Textiles and Clothing Standards Policy Committee (TCM/-) to Technical Committee TCM/35, upon which the following bodies were represented: Association of Consulting Engineers British Polyo
4、lefin Textiles Association British Textile Technology Group Chemical Industries Association Department of Transport Department of Transport (Transport and Road Research Laboratory) ERA Technology Ltd. Federation of Civil Engineering Contractors Institution of Civil Engineers Lambeg Industrial Resear
5、ch Association Ministry of Agriculture, Fisheries and Food Ministry of Defence Society of Engineers Incorporated Amendments issued since publication Amd. No.DateComments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 12:57:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6906-7:1990 BSI 02-1
6、999i Contents Page Committees responsibleInside front cover Forewordii 1Scope1 2Definitions1 3Principle1 4Apparatus1 5Test specimens1 6Procedure1 7Calculations2 8Test report3 Appendix A Accuracy7 Figure 1 Constant head in-plane water flow apparatus (example of typical arrangement)3 Figure 2 Water vi
7、scosity correction factor4 Figure 3 Typical plot of hydraulic transmissivity versus hydraulic gradient under several normal stresses5 Figure 4 Typical plot of hydraulic transmissivity versus normal compressive stress under several gradients5 Figure 5 Typical plot of flow rate per unit width versus n
8、ormal compressive stress under several hydraulic gradients6 Publication(s) referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 12:57:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6906-7:1990 ii BSI 02-1999 Foreword This Part of BS 6906 has been prepared under the d
9、irection of the Textiles and Clothing Standards Policy Committee. This standard describes a method for determination of water flow through the plane of the geotextile under specified normal compressive stress and hydraulic gradient and is an additional method to that described in BS 6906-3 which det
10、ermines water flow normal to the plane of the geotextile. Other Parts of BS 6906 are as follows. Part 1: Determination of the tensile properties using a wide width strip; Part 2: Determination of the apparent pore size distribution by dry sieving; Part 3: Determination of water flow normal to the pl
11、ane of the geotextile under a constant head; Part 4: Determination of the puncture resistance (CBR puncture test); Part 51): Determination of creep; Part 6: Determination of resistance to perforation (cone drop test); Part 81): Method for investigating sand-geotextile frictional behaviour by direct
12、shear. Information on the accuracy of the test is given in Appendix A. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer imm
13、unity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in th
14、e amendment table on the inside front cover. 1) In preparation. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 12:57:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6906-7:1990 BSI 02-19991 1 Scope This Part of BS 6906 describes an index test procedure for determining the constant head wate
15、r flow within the manufactured plane of geotextiles and related products under varying compressive stresses and typical hydraulic gradients. The method can be adapted to model particular field conditions, e.g. by employing other contact surfaces, stresses and hydraulic gradients. The procedure is li
16、mited to geotextiles and related materials that allow continuous flow paths to develop parallel to the longest edge of the specimen tested. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this Part of BS 6906 the
17、following definitions apply. 2.1 normal stress the stress component (in kPa) normal to a given plane 2.2 hydraulic transmissivity the volumetric flow rate of water per unit width of specimen per unit gradient in a direction parallel to the plane of the specimen 2.3 in-plane flow fluid flow confined
18、to a direction parallel to the plane of the geotextile 2.4 gravity flow flow in a direction parallel to the plane of the geotextile driven predominantly by a difference in elevation between the inlet and outlet points of a specimen 2.5 pressure flow flow in a direction parallel to the plane of the g
19、eotextile driven predominantly by a differential fluid pressure 2.6 hydraulic gradient ratio of the length of specimen in the flow direction to the total head loss across the specimen 3 Principle The in-plane water flow is determined by measuring the quantity of water that passes along the test spec
20、imen in a known time and under specified normal stress and hydraulic gradient. 4 Apparatus 4.1 Constant head in-plane water flow apparatus, (typical unit illustrated in Figure 1). The loading platen shall be a very good fit, and shall not leak. There shall be provision for maintaining a constant wat
21、er level at several different water levels to correspond to, at least, hydraulic gradients of 0.1 and 1.0. The apparatus shall be substantially leak free when the platen is seated in the unit without the test specimen. 4.2 Loading mechanism, capable of sustaining a constant normal stress on the spec
22、imen ranging from 10 kPa to at least 250 kPa. 4.3 Device such as a dial gauge, to measure changes in specimen thickness during the test (when this is specified). NOTEFor details of the source of supply of a suitable apparatus apply to Enquiries Section, BSI, Linford Wood, Milton Keynes, MK14 6LE, en
23、closing a stamped, addressed envelope for reply. 5 Test specimens 5.1 Selection of test specimens Take specimens at random from the sample. Unless otherwise agreed between the interested parties, take specimens no nearer than 100 mm from the selvedge of the geotextile. 5.2 Number and dimensions of t
24、est specimens Unless otherwise agreed between the interested parties, cut three test specimens from the sample with the length parallel to the machine direction, and three specimens with the length parallel to the cross direction. The specimens shall be clean and dry, and measure 300 mm in the lengt
25、h or flow direction and 200 mm in the width direction. NOTEIt is important that the specimen width is not undersize, i.e. a good push tight fit. Where it is necessary to determine results to within a given confidence interval of the mean, determine the number of test specimens in accordance with BS
26、2846-2. 6 Procedure 6.1 Contact surface The surfaces contacting the specimens shall be one of the following. a) the hard base of the apparatus and the lower rigid surface of the loading platen; b) other materials such as closed cell foam rubber or soil used to model field situations. Licensed Copy:
27、sheffieldun sheffieldun, na, Wed Dec 06 12:57:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6906-7:1990 2 BSI 02-1999 NOTE 1Option b) should be by agreement between the interested parties and should be reported under item c) of the test report (see clause 8). NOTE 2The nature of the material in c
28、ontact with the geotextiles in the field may be modelled using this test method. A rigid platen on one or both sides of the specimen simulates like surfaces encountered in the field (e.g. concrete walls, stiff geomembranes, etc.) where intrusion into the geotextile pore space is not anticipated. Whe
29、re pore intrusion is expected, as is the case when the geotextile is in contact with soil, a closed-cell foam rubber layer (no continuous flow paths) may be placed between the platen and the geotextile specimen. 6.2 Hydraulic gradient Perform the test using hydraulic gradients of 0.1 and 1.0. NOTEOt
30、her hydraulic gradients may be selected, by agreement between the interested parties, which are more appropriate for the end use of the material and for the specific field conditions. This should be reported under item f) of the test report (see clause 8). 6.3 Applied normal stress Apply normal stre
31、ss values of 25,100 and 250 kPa. NOTEOther stress values may be employed, by agreement between the interested parties, to simulate specific field situations. This should be reported under item f) of the test report (see clause 8). 6.4 Test method 6.4.1 Place the lower contact surface material or sub
32、stratum (if required) on the base and then place the test specimen on top of the substratum ensuring that all wrinkles, folds, etc. are removed. Place the upper contact surface material or superstratum (if required) over the specimen in a similar manner. Lower the loading platen on to the test speci
33、men (and model contact surfaces, if present). 6.4.2 Place a small seating stress of 2 kPa on the specimen and fill the reservoir with water to allow water to flow through the test specimen. Visually check for preferential flow paths along the boundaries of the test specimen. If such flows are observ
34、ed, re-seat or discard the test specimen as required. 6.4.3 Seat the specimen under the lowest normal stress to be used (usually 25 kPa). Record the change in specimen thickness (if required). NOTEThickness measurement is not applicable if model contact surfaces are employed. 6.4.4 Fill the reservoi
35、r to the level corresponding to the lowest hydraulic gradient to be used (usually 0.1). Use water from a still tank for flow values less than 0.2 L/s. NOTEFor practical reasons, water direct from the mains supply may be used for water flows greater than 0.2 L/s. 6.4.5 Allow water to flow through the
36、 specimen under these conditions for a minimum of 10 min or until steady uniform flow has been achieved. NOTEFor some materials, especially those exhibiting compression creep, the stress may tend to decay during the test if, say, a hydraulic jack is employed to apply the stress. In this case, contin
37、ual re-adjustment of the stress will be necessary to maintain a constant value during the test period. 6.4.6 Collect a sample of water flowing over the outlet weir for a known time period. The volume of this sample shall be not less than 0.5 L or for very high flow materials the period shall be not
38、less than 5 s. Record the volume collected and note the water temperature. Repeat this procedure two more times, i.e. three flow readings in all. 6.4.7 Increase the hydraulic gradient to the next highest to be used (usually 1.0) whilst maintaining the stress value. Repeat 6.4.6. 6.4.8 Repeat 6.4.7 f
39、or any and all higher hydraulic gradients. 6.4.9 Increase the normal stress to the next highest value (usually 100 kPa). Repeat 6.4.4 to 6.4.7. 6.4.10 Continue increasing the stress and repeating 6.4.4 to 6.4.7 until readings at the highest stress value to be used have been taken. 6.4.11 Repeat the
40、whole sequence of operations 6.4.1 to 6.4.10 for the remaining test specimens. 7 Calculations 7.1 Calculate the hydraulic transmissivity, if required, using the following equation: = (QL)/(WH) where NOTEIf the hydraulic transmissivity calculated in this test method is to be used to determine the coe
41、fficient of in-plane permeability of the specimen, the test should be conducted under laminar flow conditions. The constant head technique may be used as a check to determine if laminar or turbulent flow conditions exist. To determine the flow regime under specific test conditions, plot the flow rat
42、e per unit width of the specimen versus the hydraulic gradient under each of the applied normal stresses. The data points for tests performed under each normal stress form a straight line passing through the origin if the test was conducted under laminar flow conditions. A non-linear response sugges
43、ts that turbulent flow conditions exist and Darcys law (i.e. the flow rate is linearly proportional to the hydraulic gradient under laminar flow conditions) is not considered valid. is the hydraulic transmittivity (in m2/s); Qis the average quantity of fluid discharged per unit time (in m3/s); Lis t
44、he length of the specimen (in m); Wis the width of the specimen (in m); His the difference in total head across the specimen (in m). Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 12:57:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6906-7:1990 BSI 02-19993 7.2 Correct the hydraulic transm
45、issivity to that for 20 C by multiplying the hydraulic transmissivity by the ratio of the viscosity of water at test temperature to the viscosity of water at 20 C (see Figure 2). 7.3 Results can be expressed in one of the following ways: a) as a plot of hydraulic transmissivity versus hydraulic grad
46、ient (see Figure 3); b) as a plot of hydraulic transmissivity versus normal compressive stress (see Figure 4); c) as a plot of flow rate per unit width versus normal compressive stress (see Figure 5). 8 Test report The test report shall include the following particulars: a) the number and date of th
47、is British Standard, i.e. BS 6906-7:1990; b) full identification details of the sample tested; c) the contact surfaces employed; d) the flow values expressed either as flow per unit width (in m3s1m1) or as hydraulic transmissivity (in m2s1) at each hydraulic gradient and normal stress condition empl
48、oyed. Mean, standard deviation and coefficient of variation of temperature corrected flow values for the test specimens in each material direction shall be reported; e) all details of differences from the procedures, e.g. contact surfaces, hydraulic gradient and normal stress; f) the temperature of
49、the water (in C); g) the thickness measurements (if required); The test report may also include the following particulars h) graphical representation of data (if required) as shown in Figure 3, Figure 4 and Figure 5. Figure 1 Constant head in-plane water flow apparatus (example of typical arrangement) Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 12:57:47 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6906-7:1990 4 BSI 02-1999 Figure 2 Water viscosity correction factor Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 12:57: