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1、1AS 1289.6.1.31998 Australian Standard Methods of testing soils for engineering purposes Method 6.1.3: Soil strength and consolidation testsDetermination of the California Bearing Ratio of a soilStandard field-in-place method 1SCOPEThis Standard sets out the procedure for the field-in-place or in si
2、tu determination of the California Bearing Ratio (CBR) of a soil. The method is applicable to both fine-grained and medium-grained soils as defined in AS 1289.0. 2REFERENCED DOCUMENTSThe following documents are referred to in this Standard: AS 1152Specification for test sieves 1289Methods of testing
3、 soils for engineering purposes 1289.0Method 0: General requirements and list of methods 1289.2.1.1Method 2.1.1: Soil moisture content testsDetermination of the moisture content of a soilOven drying method (standard method) 1289.5.3.1Method 5.3.1: Soil compaction and density testsDetermination of fi
4、eld density of a soilSand replacement method using a sand-cone pouring apparatus 1289.5.3.2Method 5.3.2: Soil compaction and density testsDetermination of field dry density of a soilSand replacement method using a sand pouring can, with or without a volume displacer 1289.5.8.1Method 5.8.1: Soil comp
5、action and density testsDetermination of field density and field moisture content of a soil using a nuclear surface moisture-density gaugeDirect transmission mode 1289.6.1.1Method 6.1.1: Soil strength and consolidation testsDetermination of the California Bearing RatioStandard laboratory method for
6、a remoulded specimen 2103Dial gauges and dial test indicators 2193Methods for calibration and grading of force-measuring systems of testing machines 3APPARATUSThe following apparatus is satisfactory but alternative designs may be employed provided that the essential requirements of the apparatus are
7、 met and the test procedure is followed: (a)Steelpenetrationpiston ofa49.6 0.1 mmdiameteroverthelengthofthe penetration and at least 150 mm long. The length of the piston will depend upon the number of surcharges and the depth of penetration required. Suitable extensions may be required. COPYRIGHT A
8、ccessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.6.1.319982 (b)Force-measuring device capable of (i)meeting the accuracy and repeatability requirements of AS 2193 Grade C testing machines for the range of forces used in the test; and (ii)indicating seating loads of approximately 50 N and
9、 approximately 250 N (see Note 1). (c)Displacement measuring device (e.g. dial gauges) capable of (i)measuring the expected range of travel, graduated to 0.01 mm and meeting the accuracy and repeatability requirements of AS 2103; and (ii)being equipped with an adjustable extension clamp. (d)One annu
10、lar metal surcharge and several slotted metal surcharges of 250 mm in diameter,eachhavingamassof4.50.04 kgandwithacentreholeof approximately 55 mm in diameter. (e)Mechanical screw-jack equipped with a special swivel for applying load to the piston at a controlled rate of 1 0.2 mm/min (see Note 2). (
11、f)Suitable reaction, e.g. ballasted truck with a reaction beam fitted either front or rear, approximately 0.5 m above the ground to provide a reaction of about 50 kN at the beam, and two truck jacks. The lower flange of the reaction beam shall be nearly horizontal when the ballasted truck is raised
12、to take the load off the springs. (g)Reference beam and supports consisting of 50 mm 50 mm 8 mm low carbon steel angle or other section of equivalent stiffness with supports to give a length between supports of not less than 2.5 m. (h)Watch or stop clock readable in seconds. (i)19 mm sieve complying
13、 with AS 1152. (j)Other apparatus such as straight edge and excavating tools. 4PREPARATION OF THE TEST AREALevel the surface of the soil to be tested over an area of approximately 0.5 m diameter and clear all loose material (see Note 3). Commence the test as described in Clause 6 as soon as practica
14、ble after preparation of the test area, ensuring that moisture is not lost from the surface (see Note 4). 5ASSEMBLY OF APPARATUSAssemble the apparatus as follows: (a)Where a ballasted truck is used, position the truck with the centre of the reaction beam directly over the surface to be tested. Place
15、 the truck jacks beneath the ends of the reaction beam and take the load of the truck off the springs. (b)Clamp the mechanical screw-jack to the underside of the reaction beam immediately above the surface to be tested. Connect the force-measuring device to the end of the jack and connect the penetr
16、ation piston to the bottom of the force-measuring device, using extensions as necessary, so that the piston is 20 mm to 50 mm from the surface to be tested. (c)Loosen the swivel head on the jack and bring the piston to a vertical position. Lock the apparatus into position. (d)Place the circular surc
17、harge plate centrally beneath the penetration piston. (e)Position the reference beam so that it is centrally located to the surface being tested adjacent to but not touching the penetration piston (see Figure 1) and firmly seated on the ground. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19
18、Dec 2007 3AS 1289.6.1.31998 6PROCEDUREThe procedure shall be as follows: (a)Seat the penetration piston with the smallest possible load (see Note 5), not exceeding 50 N for expected CBR values equal to or less than 30 and 250 N for expected CBR values greater than 30. Apply surcharges as required (s
19、ee Note 6). (b)Clamp the penetration gauge extension bracket to the piston with the gauge stem resting upon the reference beam. (c)Read, or set to zero, the force-measuring device and the displacement measuring device used to measure penetration. (d)Apply the load with a constant rate of penetration
20、 of 1 0.2 mm/min. Record load readings at penetrations of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 7.5, 10.0 and 12.5 mm (see Notes 7 and 8). (e)Determine the moisture content of the top 30 mm layer (w30) from immediately under the piston in accordance with AS 1289.2.1.1. (f)Determine the percentage
21、by mass of material retained on the 19 mm sieve for the material immediately below the penetration piston from the sample used to determine moisture content. (g)At a site adjacent to the penetration site, determine the field density of the soil in accordance with AS 1289.5.3.1, AS 1289.5.3.2, or AS
22、1289.5.8.1 and the field moisture content in accordance with AS 1289.2.1.1 or AS 1289.5.8.1. 7CALCULATIONS (a)Plot the load-penetration curve (see Figure 6 of AS 1289.6.1.11998). When the load-penetration curve is concave upward initially (because of surface irregularities orothercauses)adjustthezer
23、opointasshowninFigure 6,curve3of AS 1289.6.1.11998. If the correction is greater than 2 mm, the load-penetration curve shall be presented in the test report. (b)Read from the load-penetration curve, corrected if required, the force value in kN at penetrations of 2.5 mm and 5.0 mm and calculate the b
24、earing ratio for each by dividing by 13.2 kN and 19.8 kN, respectively and multiplying by 100. Record the greater value of the calculated values as the CBR of the material. 8TEST REPORTReport the following test results and general information. (a)CBR of the soil to the nearest value, in percent as f
25、ollows: CBR percent Report value to the nearest 50 0.5 1 5 10 (b)The penetration at which the CBR was determined, in millimetres. (c)The moisture content of the top 30 mm (w30) of the soil after penetration, in percent. (d)The field dry density of the soil adjacent to the penetration site, in t/m3.
26、(e)The field moisture content of the soil adjacent to the penetration site, in percent. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.6.1.319984 (f)The percentage by mass of the material retained on the 19 mm sieve, of the top 30 mm layer. (g)The mass of surcharges applied
27、during penetration testing. (h)When available, the soil description. (i)The location of the field test and date of test. (j)The load penetration curve, if the correction to the test curve is greater than 2 mm. (k)The number of this Australian Standard, i.e. AS 1289.6.1.3. NOTES: 1Essential dimension
28、s are toleranced. 2All dimensions are in millimetres. FIGURE 1APPARATUS FOR CBR FIELD-IN-PLACE METHOD COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 5AS 1289.6.1.31998 NOTES ON TEST: 1Force-measuring deviceThe indicator points of the force-measuring device at the seating loads of ap
29、proximately, but not greater than, 50 N and 250 N need not necessarily meet the Grade C requirements of AS 2193 but should be displayed as definite numbers or marks. 2Loading jackPower-operated hydraulic jacks may be used. The use of a manually operated hydraulic jack is not recommended owing to the
30、 tendency for the load to be applied in a series of pulses. 3Surface preparationWith coarse-grained soils, the surface may be levelled with a thin cover of sand. 4Moisture lossTo limit loss of moisture from the prepared soil surface during the assembly of the apparatus, it is desirable to cover the
31、surface with waterproof canvas or similar material. 5Seating loadThis initial load is required to ensure satisfactory seating of the piston and it is considered as the zero load when plotting the load-penetration curve. 6SurchargesSurcharges may be applied to simulate the confining effects of the ov
32、erlying material layers (see Figure 2). 7Rate of penetrationIt may be necessary to take load readings at closer intervals to control the rate of penetration. 8Termination of testThe test may be terminated after 7.5 mm penetration if the penetration proceeds without any increase, or decrease in the l
33、oad. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.6.1.319986 FIGURE 2SELECTION OF SURCHARGE COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 7AS 1289.6.1.31998 NOTES Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.6.1.319988 This Australian Sta
34、ndard was prepared by Committee CE/9, Testing of Soils for Engineering Purposes. It was approved on behalf of the Council of Standards Australia on 10 July 1998 and published on 5 August 1998. The following interests are represented on Committee CE/9: Australian Geomechanics Society AUSTROADS Crushe
35、d Stone Association of Australia Department of Industry, Sport and Tourism, Scientific Services Laboratory, AGAL Institution of Engineers Australia National Association of Testing Authorities, Australia University of Sydney Review of Australian Standards.To keep abreast of progress in industry, Aust
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39、iate action taken. Originated as part of AS A891966. Previous edition AS 1289.F1.31977. Revised and redesignated AS 1289.6.1.31998. This Standard was issued in draft form for comment as DR 96557. CopyrightSTANDARDS AUSTRALIA Users of Standards are reminded that copyright subsists in all Standards Au
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44、. The use of material in print form or in computer software programs to be used commercially, with or without payment, or in commercial contracts is subject to the payment of a royalty. This policy may be varied by Standards Australia at any time. ISBN 0 7337 2144 3Printed in Australia Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 Thi s page has been l ef t i nt ent i onal l y bl ank. Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007