Some standard content:
Industry Standard of the People's Republic of China
Code for test and measurement of geosyntheticsSL/T235—1999
Nanjing Hydraulic Science Research Institute
Editor:
China Geosynthetics Engineering Association
Approving department: Ministry of Water Resources of the People's Republic of China Effective date: April 1, 1999
Ministry of Water Resources of the People's Republic of China
Notice of the competent department on approval and issuance of "Code for test and measurement of geosynthetics" SL/T 235-1999
Shuiguoke [1999782] No.
According to the Ministry's plan for the formulation and revision of technical standards for water conservancy and hydropower, the "Code for test and measurement of geosynthetics" was formulated by the International Cooperation and Science and Technology Department of the Ministry of Water Resources, with Nanjing Hydraulic Science Research Institute and China Geosynthetics Engineering Association as the main editors. It has been reviewed and approved as a water conservancy industry standard and is issued. The name and number of the standard are: "Geosynthetics Test Procedure" SL/T235--1999. This standard shall be implemented from April 1, 1999. During the implementation process, please pay attention to summarizing experience. If there are any questions, please inform the host department in writing, and it will be responsible for interpretation. The standard text is published and distributed by China Water Resources and Hydropower Press. February 24, 1999bzxZ.net
The purpose of compiling this procedure is to make the test methods of geosynthetics gradually tend to standardization and unification, and to move closer to international standards. In 1988, the former Geosynthetics Technology Cooperation Network organized the compilation of the "Geotextile Test Method Reference Standard", and in 1990, the former Ministry of Water Resources and Electric Power commissioned Nanjing Water Resources Research Institute to preside over the compilation of the "Geosynthetics Test Manual". These works have played a positive role in the increasing unification of test methods. In recent years, due to the great development of the varieties and applications of geosynthetics, the existing test items need to be further enriched and revised. The Geosynthetics Engineering Association and the Ministry of Water Resources have agreed to jointly compile this procedure. This code includes 19 test items, mainly referring to the American Standard (ASTM), International Standard (ISO) and the National Standard (GB), National Standard (DIN), and the Geotextile Engineering Manual of the US Highway Administration (FHWA). The principle of citing and formulating these methods is to combine my country's national conditions and based on the relatively mature experience of geotechnical tests for many years. A small number of methods are formulated based on the existing conditions of the laboratory, after joint research and practical verification. The unit for interpreting this code: International Cooperation and Science and Technology Department of the Ministry of Water Resources The main editor of this code: Nanjing Hydraulic Research Institute China Geosynthetics Engineering Association
The main drafters of this code: Ma Meiying Liu Zongyao Wang Yuren Wang Zhenghong Chen Huan Yang Canwen 162
1.0.1 In order to promote the application of geosynthetics in engineering construction and unify the technical requirements for material testing, this code is specially formulated. 1.0.2 This code is applicable to the testing of geosynthetics used in water conservancy, railways, highways, water transportation, construction, environment and other projects. 1.0.3 The properties of geosynthetics are affected by factors such as test methods, load properties, sample size, loading rate, and test temperature. The test should be carried out in accordance with the relevant provisions of this code.
1.0.4 In addition to complying with the provisions of this code, the test of geosynthetics should also comply with the provisions of the current relevant national standards and specifications. 2 Terms and symbols
2.1 Terms
2.1.1 Equivalent aperture (or apparent aperture) When the granular material is screened with geotextile as the sieve cloth, when the screening rate of a granular material (the ratio of the weight of the granular material passing through the fabric to the total weight of the granular material) is 5%, the particle size is defined as the equivalent aperture of the geotextile. 2.1.2 Vertical permeability
The infiltration velocity when the hydraulic gradient of the water flow perpendicular to the plane of the geotextile is equal to 1. 2.1.3 Water permeability
The infiltration velocity when the water level difference of the water flow perpendicular to the plane of the geotextile is equal to 1. 2.1.4 Horizontal permeability coefficient
The infiltration velocity when the hydraulic gradient of water flow along the plane of geotextile is equal to 1. 2.1.5 Hydraulic conductivity
The amount of water transported by water flow along the plane of geotextile within a unit width when the hydraulic gradient is equal to 1. 2.1.6 Tensile strength
The maximum tensile force that the sample can withstand when stretched, which occurs at or before breaking. 2.1.7 Elongation
The strain corresponding to the maximum tensile force when the sample is stretched. 2.1.8 Holding strength
The maximum tensile force that occurs during the stretching of the sample under the condition of being partially clamped within the width of the sample. 2.1.9 Tear strength
The maximum tearing force that occurs during the process of the sample gradually expanding the crack along the specified cut to the entire sample. 2.1.10 Bursting strength
Hydraulic pressure is applied in the vertical direction of the sample to expand the sample until it is destroyed. The hydraulic pressure at the time of destruction is called the bursting strength. 2.1.11CBR bursting strength
The maximum top pressure during the vertical penetration of a cylindrical mandrel with a diameter of 50mm into the sample. 2.1.12 Puncture strength
The maximum puncture force during the vertical penetration of a rigid mandrel with a diameter of 8mm into the sample. 2.1.13 Compression yield strength
The ability of the core of a plastic drainage belt to resist fracturing and tipping damage under external forces. 163
2.1.14 Drainage belt water flow
The longitudinal water flow capacity of the core and filter membrane complex of the drainage belt along the cross section of the drainage belt under the action of lateral pressure. 2.1.15 Flatness
The ratio of the radial deformation of a soft permeable pipe under the action of upper composite pressure to the pipe diameter. 2.1.16 Creep
2.1.17 Tensile creep failure strength
The single width strength of the material that will fail at a specified time when the creep test is carried out under specified conditions. 2.1.18 Gradient ratio
In the siltation test, the ratio of the composite hydraulic gradient of the geotextile and the adjacent 25mm soil sample above it to the hydraulic gradient of the soil sample ranging from 25mm to 75mm above it.
2.2 Symbols
A-area;
B-width;
C, coefficient of variation;
D——pipe diameter;
F total horizontal force,
f-soil-geotextile interface friction coefficient,G—.—unit area weight;
H——seepage length;
△h Water level difference,
i-—hydraulic gradient;
chi—vertical permeability coefficient;
kn—horizontal permeability coefficient;
km—geomembrane permeability coefficient,
L-—length,
O95——equivalent pore size;
Ptotal normal force;
force—normal pressure;
Pr——bursting strength;
Q——water flow,
duration,
T. CBR bursting strength;
T.-holding strength;
Tp--puncture strength;
T. tensile strength,
T, tear strength;
U-flatness,
W-water seepage;
-average value;
-thickness;
E--elongation;
9--water conductivity;
-mean square deviation;
tp--pull-out friction;
t. Shear force;
Y water permeability.
Common provisions for test methods
3.1 Purpose and scope of application
The sample preparation methods, sample humidity adjustment and test value calculation formulas specified in this chapter for geosynthetics are common provisions that should be followed in subsequent tests.
3.2 Reference standards
ISO9862-90 "Sampling and preparation of specimens for geotextiles" GB6529-86 "Atmospheres for conditioning and testing textiles" 3.3 Sample preparation method
3.3.1 Sample preparation principles:
1 The specimens for each test should be randomly cut from the length and width of the sample, and the distance from the edge of the sample should be equal to or greater than 100mm. The sample to be tested should not be less than 1 extended meter (or 2m2). 2 The specimen should not contain dust, creases, holes, damaged parts and visible points. 3 When cutting more than two specimens for the same test, they should be avoided from being located in the same longitudinal and transverse positions, that is, the trapezoidal sampling method should be used. If it is unavoidable (such as roll packaging, narrow width), the situation should be noted in the test report. 4 The accuracy requirements should be met when cutting the specimen.
5 Before cutting the specimen, there should be a cutting plan first, and then cutting. 6 All samples used in each test should be numbered. 3.3.2 The above provisions apply to all types of geotextiles, geomembranes and geocomposites, but do not include special-purpose products such as geogrids. 3.4 Sample Humidity Conditioning
3.4.1 The sample should be placed in an environment with a temperature of 20 ± 2 ° C, a relative humidity of 60 ± 10% and standard atmospheric pressure for 24 hours. 3.4.2 If it is confirmed that the sample is not affected by the environment, the humidity treatment can be omitted, but the temperature and humidity during the test should be noted in the record. 3.5 Calculation formula for arithmetic mean, standard deviation and coefficient of variation 3.5.1 Calculate the arithmetic mean according to the following formula:
Where n is the number of tests;
xi is the test value of the i-th sample;
-the arithmetic mean of the test values of n samples. 3.5.2 Calculate the standard deviation according to the following formula:
Where the symbols have the same meaning as in formula (3.5.1).
3.5.3 Calculate the coefficient of variation C according to the following formula:
Where the symbols have the same meaning as in formula (3.5.1).
×100%
Determination of unit area weight
Purpose and scope of application
4.1.1 This test is used to determine the unit area weight of geosynthetics. 4.1.2 This test is applicable to all types of geotextiles, geomembranes and geocomposites. 4.2 Reference standard
) "Method for determination of unit area mass of geotextiles". ISO 9864--90
Test equipment and tools
4.3.1 Scissors.
4.3.2 Ruler, minimum graduation value is 1mm.
4.3.3 Balance, sensitivity 0.01g.
4.4 Operating steps
4.4.1 Sample preparation:
1 Cut the sample according to the provisions of 3.3.1 of this specification. 2 The area of the sample should not be less than 100cm2, and the cutting and measurement readings of the sample length and width should be accurate to 1mm. 3 The number of samples should be not less than 10 and they should be numbered. 4.4.2 Weighing:
Weigh the cut samples one by one on the balance in the order of numbers, and the readings should be accurate to 0.01g. 166
4.5.1Calculate the unit area weight G of each sample according to the following formula: M
Where G—unit area weight of the sample·g/m\; M-sample weight, g;
A—sample area, m2.
4.5.2Calculate the average value G, standard deviation α and coefficient of variation C of the unit area weight according to the provisions of 3.4 of this regulation. 4.6 Record
4.6.1See Table A1 for the record format of the unit area weight test.
Thickness determination
Purpose and scope of application
5.1.1 This test is used to determine the thickness of geosynthetics under a certain pressure. 5.1.2 This test is applicable to all types of geotextiles, geomembranes and geocomposites. 5.2 Reference standards
ISO9863-90 "Method for determination of thickness of geotextiles". 5.3 Test equipment and instruments
5.3.1 Reference plate: The diameter should be 50 mm larger than the diameter of the pressure block, see Figure 5.3.1. Figure 5.3.1 Thickness measuring instrument
1——Digital indicator 2-pressure block 13——Test sample + 4—reference plate, 5—balance weight 16—base weight 5.3.2 Pressure block: A round pressure block with a smooth surface, a bottom area of 25 cm and a weight of 5 N. The pressure block is placed on the test sample and a pressure of 2 ± 0.01 kPa is applied to the test sample.
5.3.3 Pressure gauge: output greater than 500N.
5.3.4 Dial gauge: minimum scale value 0.01mm. 5.3.5 Stopwatch: minimum scale value 0.1s.
5.4.1 Sample preparation:
1 Cut the sample according to 3.3.1 of this regulation. 5.4 Operation steps
2 The number of samples should be no less than 10 and they should be numbered. 5.4.2 Operation method for measuring thickness under 2kPa pressure: 1 Clean the reference plate and the pressure block, place the pressure block on the reference plate, and adjust the zero point of the dial gauge. 2 Lift the pressure block, place the sample naturally flat between the reference plate and the pressure block, and gently put down the pressure block. The sample is subjected to a force of 2±0.01kPa. Start timing after contact, and record the dial gauge reading when it reaches 30s. Lift the pressure block and take out the sample. 3 Repeat the above steps to test 10 samples. 5.4.3 Method of measuring thickness under 20kPa and 200kPa pressure: 1 Place the reference plate on the pressure gauge, then place the pressure block on the reference plate, and adjust the zero point of the dial indicator. 2 Lift the pressure block, place the sample naturally flat between the reference plate and the pressure block, gently put down the pressure block, adjust the load on the pressure gauge, make the sample force reach 20±0.1kPa, start timing after the pressure is added, and record the dial indicator reading when it reaches 30s. 3 Still adjust the load on the pressure gauge according to the above steps, make the sample force reach 200±1kPa, start timing after the pressure is added, and record the dial indicator reading when it reaches 30s.
4 Repeat steps 5.4.3-2 and 5.4.3--3 of this article to test 10 samples. 5.5 Calculation and drawing
5.5.1 Calculate the arithmetic mean value, standard deviation and coefficient of variation C of the thickness of 10 samples under each pressure according to the provisions of 3.4 of this regulation.
5.5.2 Draw a thickness-pressure relationship curve, with the horizontal axis being the logarithm of pressure and the vertical axis being the average thickness, see Figure 5.5.2. 6.0m
468102040601002004006001000
Pressure (kPa)
Figure 5.5.2 Thickness-pressure relationship curve of nonwoven geotextile 5.6 Record
5.6.1 See Table A2 for the record format of thickness test. 168
6 Aperture test (dry sieving method)
6.1 Purpose and scope of application
6.1.1 This test uses the dry sieving method to determine the equivalent pore size EOS (or apparent pore size AOS) and pore size distribution curve of geotextiles. 6.1.2 This test is applicable to all types of geotextiles and geocomposites with pores. 6.2 Reference standards
ASTMD4751-87 "Determination of apparent pore size of geotextiles"; GB6003-85 "Test sieve"
GB9909-88 "Sieve shaker".
6.3 Test equipment and tools
6.3.1 Standard test sieve: 200mm in diameter. 6.3.2 Sieve shaker: The device with horizontal shaking and vertical vibration (or slapping) shall comply with the provisions of GB9909-88. 6.3.3 Balance: weighing 200g, sensitivity 0.01g. 6.3.4 Granular materials for sieve shaker. The washed and dried granular material is graded and prepared by sieving method, and the standard test sieve aperture is graded as follows: 0.063~~0.075mm, 0.075~0.090mm, 0.090~0.106mm, 0.106~0.125mm, 0.125~0.150mm, 0.150~0.180mm, 0.180~0.250mm, 0.250~0.350mm, etc. 6.3.5 Other supplies: stopwatch, soft brush. 6.4 Sample preparation
6.4.1 Cut the sample according to the provisions of 3.3.1 of this regulation, and its diameter should be larger than the sieve diameter. 6.4.2 Five samples should be taken. If the sample is a needle-punched geotextile, after vibrating the sieve, if the particles embedded in the fabric are not easy to be cleared out, the fabric sample cannot be reused. At this time, the number of samples is 5×n (n is the selected particle size grade). 6.5 Change steps
6.5.1 Place the sample on the sieve and fix it. 6.5.2 Weigh 50g of granular material and spread it evenly on the surface of the sample. 6.5.3 Clamp the sieve, receiving tray and sieve cover with the sample on the vibrating screen machine, start the machine and vibrate for 10 minutes. 6.5.4 After stopping the machine, weigh the granular material that passes through the sample, then gently vibrate the sieve frame or use a brush to gently wipe off the particles on the surface and embedded in the sample. Perform 5 average tests on the same level of particles in this way. 6.5.5 Repeat steps 6.5.2 to 6.5.4 of this section on the same sample with another level of granular material. When measuring the aperture distribution curve, the screening rate of particles of not less than 3 to 4 levels of continuous classification should be obtained, and the test points should be evenly distributed. If only the equivalent aperture O95 is measured, the screening rate of two groups of about 95% is sufficient.
6.6 Calculation and drawing
6.6.1 Calculate the screening rate Ri of a certain level of particles according to the following formula: M.-M.
Where M,—the amount of particles put in during screening, g;
M; the weight of particles in the bottom plate after screening (screened amount), g. 6.6.2 Calculate the average screening rate of 5 parallel tests according to the following formula: Where the symbols are the same as those in formula (6.6.1).
6.6.3 Use the average screening rate of particles of each level and the average particle size of the corresponding particles of each level to draw the aperture distribution curve on semi-logarithmic paper, see Figure 6.6.3.
0.,040.06 0.08 0.10
Aperture (mm)
Figure 6.6.3 Aperture distribution curve
6.7.1 See Table A3 for the format of aperture test record.
Vertical penetration test
7.1 Purpose and scope of application
7.1.1 This test is used to determine the vertical permeability coefficient and water permeability of geotextiles under constant water head of 10 cm or laminar flow conditions. 7.1.2 This test is applicable to all types of geotextiles and geocomposites with water permeability. 7.2 Reference standard
ISO/FDIS11058-98T(E) "Vertical permeability test of geotextiles and related products without pressure". 170
7.3.1 Sample holder, see Figure 7.3.1. 7.3 Test equipment and tools
1 The effective water flow area of the holder is 20 to 100 cm, and it should be able to hold single and multiple geotextile samples.
2 The sample and the surrounding wall of the holder must be well sealed and there must be no leakage. 7.3.2 Upstream and downstream water level containers:
1 The container should have an overflow device to maintain a constant water head during the test. 2 The container should be able to adjust the water level, and the water head range is 1 to 60 mm. 7.3.3 The pipes of the measuring system should be short and thick to reduce the head loss. 7.3.4 Others: stopwatch, measuring cylinder, suction ball, bucket, etc. 7.3.5 The newly installed measuring system should be calibrated in the empty state (without sample) to determine the head loss of the equipment itself and make corrections.
7.4 Test preparation
7.4.1 Prepare degassed water or distilled water for the test. 7.4.2 Sample preparation:
1 Cut the sample according to the provisions of 3.3.1 of this regulation. 2 Number of samples:
1) For single-piece samples, take 10 samples for parallel measurement; 2) For multiple-piece samples, take 5 groups for parallel measurement.
7.5 Operation steps
Figure 7.3.1 Schematic diagram of permeameter
1-sample holder, 2-sample,
3-overflow, 4-water level difference
7.5.1 Soak the sample in water in advance and drive out the bubbles. Place the saturated sample in the holder. During the installation operation, prevent air from entering the sample. If conditions permit, it is advisable to load the sample underwater. 7.5.2 Fill the permeameter with water, put the holder on, and install it as soon as possible. Prevent the loss of water in the sample. 7.5.3 Fill the downstream container with water, so that the water slowly seeps upward from the bottom of the sample and exhausts the air, and gradually overflows the sample. 7.5.4 Adjust the upstream water level to be higher than the downstream water level, so that the water flows from the upstream to the downstream and overflows. 7.5.5 After the upstream and downstream water level difference Ah is stable, measure Ah, start the stopwatch, use a metering device to measure the amount of seepage water in a certain period of time, and measure the water temperature.
7.5.6 Adjust the upstream water level, change the hydraulic gradient, and repeat steps 7.5.4 to 7.5.5 of this section. Draw a curve of the relationship between the seepage flow rate v and the hydraulic gradient, take the test results within the linear range, and calculate the average permeability coefficient. 7.5.7 Reinstall a sample and repeat steps 7.5.1 to 7.5.6 of this section to test the remaining samples. 7.6 Calculation
7.6.1 Calculate the permeability coefficient at 20℃ according to the following formula and indicate the water head condition: wa.n
kzoAht'n2o
wherein k20——permeability coefficient of the sample at 20℃, cm/s#W——permeable water volume, cm
a——thickness of the sample, cm;
A-—water flow area of the sample, cm;
Ah——water level difference between the upper and lower surfaces, cm;
t—time for the water volume W to pass through, s;
-dynamic viscosity coefficient of water at test water temperature T(C), kPa·s;20
-dynamic viscosity coefficient of water at 20℃, kPa·s. The dynamic viscosity coefficient ratio of water/120 is listed in Table 7.6.1. Table 7.6.1
Ratio of dynamic viscosity of waternz/n20
Temperature correction factor
Temperature correction factor
X=n/n20
7.6.2 Calculate the average permeability of the sample at different water heads and the average permeability of all samples. 7.7 Record
7.7.1 The record format of the vertical permeability test is shown in Table A4. Record
8 Horizontal permeability test
8.1 Purpose and scope of application
Temperature correction factor
IN/20
8.1.1 This test is used to determine the horizontal permeability and hydraulic conductivity of geotextiles under a certain normal pressure under a constant head of water flow. 8.1.2 This test is applicable to all types of geotextiles and geocomposites that have the ability to transmit water in the horizontal direction. 8.2 Reference standards
ASTMD4716-87 "Water conductivity of geotextiles and related products under constant water head (flow along the fabric plane) test"; ISO/FDIS12958-98E "Determination of water transfer capacity of geotextiles and related products along the fabric plane". 8.3 Test equipment and tools
8.3.1 Sample container: It should be sealed and watertight. There are two forms, see Figure 8.3.1. 8.3.2 Upstream and downstream water level container: The water level container should be able to adjust the water level, and the water level difference should remain unchanged during the test. The height of the water level container should meet the hydraulic gradient greater than 1.0.1 Purpose and scope of application
Temperature correction factor
L/20
8.1.1 This test is used to determine the horizontal permeability and hydraulic conductivity of geotextiles under a certain normal pressure under a constant head of water flow. 8.1.2 This test is applicable to all types of geotextiles and geocomposites that have the ability to transmit water in the horizontal direction. 8.2 Reference standards
ASTMD4716-87 "Test for hydraulic conductivity of geotextiles and related products under constant head (flow along the fabric plane)"; ISO/FDIS12958-98E "Determination of water transmission capacity of geotextiles and related products along the fabric plane". 8.3 Test equipment and tools
8.3.1 Sample container: It should be sealed and watertight. There are two types, see Figure 8.3.1. 8.3.2 Upstream and downstream water level containers: The water level container should be able to adjust the water level, and the water level difference should remain unchanged during the test. The height of the water level container should satisfy the hydraulic gradient greater than 1.0.1 Purpose and scope of application
Temperature correction factor
L/20
8.1.1 This test is used to determine the horizontal permeability and hydraulic conductivity of geotextiles under a certain normal pressure under a constant head of water flow. 8.1.2 This test is applicable to all types of geotextiles and geocomposites that have the ability to transmit water in the horizontal direction. 8.2 Reference standards
ASTMD4716-87 "Test for hydraulic conductivity of geotextiles and related products under constant head (flow along the fabric plane)"; ISO/FDIS12958-98E "Determination of water transmission capacity of geotextiles and related products along the fabric plane". 8.3 Test equipment and tools
8.3.1 Sample container: It should be sealed and watertight. There are two types, see Figure 8.3.1. 8.3.2 Upstream and downstream water level containers: The water level container should be able to adjust the water level, and the water level difference should remain unchanged during the test. The height of the water level container should satisfy the hydraulic gradient greater than 1.0.
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