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1、1AS 1289.6.1.11998 Australian Standard Methods of testing soils for engineering purposes Method 6.1.1: Soil strength and consolidation testsDetermination of the California Bearing Ratio of a soilStandard laboratory method for a remoulded specimen 1SCOPEThis Standard sets out the procedure for the de
2、termination of the California Bearing Ratio (CBR) of a soil when compacted and tested in the laboratory. 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
3、 for test sieves 1289Methods of testing soils for engineering purposes 1289.0Method 0: General requirements and list of methods 1289.1Method 1: Preparation of disturbed soil samples for testing 1289.2.1.1Method 2.1.1: Soil moisture content testsDetermination of the moisture content of a soilOven dry
4、ing method (standard method) 1289.5.1.1Method 5.1.1: Soil compaction and density testsDetermination of the dry density/moisture content relation of a soil using standard compactive effort 1289.5.2.1Method 5.2.1: Soil compaction and density testsDetermination of the dry density/moisture content relat
5、ion of a soil using modified compactive effort 1289.5.4.2Method5.4.2: SoilcompactionanddensitytestsCompactioncontrol testsAssignment of maximum dry density and optimum moisture content values 2103Dial gauges and dial test indicators 2193Methods for calibration and grading of force-measuring systems
6、of testing machines 3DEFINITIONSFor the purpose of this Standard, the definitions below apply. 3.1Laboratory moisture ratiothe ratio of the moisture content of the specimen to the optimum moisture content of the material as determined on material prepared in accordance with Clause 5(a), as applicabl
7、e, expressed as a percentage. 3.2Laboratory density ratiothe ratio of the dry density of the specimen to the maximum dry density of the material as determined on material prepared in accordance with Clause 5(a), as applicable, expressed as a percentage. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUT
8、ES on 19 Dec 2007 AS 1289.6.1.119982 4APPARATUSThe following apparatus shall be used: (a)Steelpenetrationpistonwitha49.60.1 mmdiameteroverthelengthof 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. (b)Loa
9、ding machine equipped with (i)a moveable head or base capable of travelling at a uniform (not pulsating) rate of 1 0.2 mm/min for use in forcing the penetration piston into the specimen; and (ii)a force-measuring device meeting the accuracy and repeatability requirements of AS 2193 Grade C testing m
10、achines for the range of forces used in the test. The force-measuring device shall be capable also of indicating seating loads of approximately 50 N and approximately 250 N (see Note 1). (c)Cylindrical metal mould (see Figure 1) of known volume with an internal diameter 152 1 mm, height 178 1 mm and
11、 wall thickness of at least 5 mm, provided with a metal extension collar and a perforated metal baseplate. (d)Steel spacer disc (see Figure 2) of 150 0.5 mm diameter and 61 0.25 mm high, fitted with a removable handle for lifting the disc from the mould. (e)Compactionapparatuscomplyingwiththerequire
12、mentsofAS 1289.5.1.1or AS 1289.5.2.1, as applicable (see Note 2). (f)Metal stem and perforated plate with a mass of 1.00 0.025 kg (see Figure 3). (g)Metal surcharges, with each surcharge having a mass of 2.25 0.025 kg, a diameter of 150 0.5 mm and with a centre hole of 55 1.0 mm diameter (see Figure
13、 4 and Note 3). (h)Two displacement measuring devices e.g. dial gauges capable of measuring the expected range of travel, graduated to 0.01 mm and meeting the accuracy and repeatability requirements of AS 2103. (i)Sieve, 19 mm and, if required, a 4.75 mm sieve, complying with AS 1152. (j)Balance of
14、sufficient capacity and limit of performance not exceeding 5 g. (k)Jack, lever, frame or other suitable device which shall be used for extruding specimens from the cylinder (optional). (l)Metal tripod, if swell is to be measured to support the dial gauge or displacement measuring device for measurin
15、g the amount of swell during soaking (see Figure 5). (m)Setting piece, if swell is to be measured and the tripod or displacement measuring device is removed from the mould during the test, to set the reading on the dial gauge or measuring device attached to the metal tripod prior to each reading in
16、the swell test. (n)Water tank or container capable of maintaining water at a level above the moulds, during soaking. (o)Other apparatus such as a mixing bowl, straightedge, filter paper and dishes. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 3AS 1289.6.1.11998 NOTES: 1Essential d
17、imensions are toleranced 2All dimensions are in millimetres FIGURE 1MOULD NOTES: 1Essential dimensions are toleranced 2All dimensions are in millimetres FIGURE 2SPACER DISC AND HANDLE COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.6.1.119984 NOTES: 1Essential dimensions are
18、toleranced 2All dimensions are in millimetres FIGURE 3STEM AND PLATE NOTES: 1 Essential dimensions are toleranced 2 All dimensions are in millimetres FIGURE 4SURCHARGES 5PREPARATION OF THE TEST PORTIONPrepare the test portion as follows: (a)Using the 19 mm sieve, sieve a representative sample of the
19、 soil prepared in accordance with the procedure prescribed in AS 1289.1. Determine the percentage of material retained on the sieve (see Notes 4 and 5). The material passing the 19 mm sieve is to be used for the test. (b)Obtain by riffling or quartering the sieved material, representative test porti
20、ons for determining maximum dry density, optimum moisture content and CBR. (c)Determine the maximum dry density and optimum moisture content in accordance with AS 1289.5.1.1 or AS 1289.5.2.1, as applicable, on one test portion. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 5AS 1289
21、.6.1.11998 If these values are assigned in accordance with AS 1289.5.4.2, take care to ensure that the values are applicable to the material prepared in Clause 5(b), i.e. if material larger than 19 mm has been replaced as detailed in Note 4, the assigned values are not applicable. (d)Thoroughly mix
22、another test portion with the required amount of water to dampen it to achieve the required laboratory moisture ratio. (e)Allow the soil test portion to cure for an appropriate time for the soil type (see Note 6). Record the duration of curing. NOTES: 1 Essential dimensions are toleranced 2 All dime
23、nsions are in millimetres FIGURE 5TYPICAL TRIPOD FOR MEASURING TEST SPECIMEN SWELL 6PREPARATION OF THE TEST SPECIMENPrepare the test specimen as follows: (a)Determine the mass of the mould (m1). (b)Insert the spacer disc, clamp the mould (with the extension collar attached) to the baseplate and plac
24、e a filter paper on top of the spacer disc. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.6.1.119986 (c)Immediately prior to compaction, thoroughly mix the cured soil and determine the moisture content (w1) of a representative fraction of the test portion in accordance with
25、 AS 1289.2.1.1. (d)Compact the specimen uniformly in the mould to the specified laboratory density ratio as follows, (see Note 7): (i)Standard compactive effortin three layers so that the compacted height of the soil is 39 mm to 44 mm in the first layer, 78 mm to 83 mm in the second layer and 117 to
26、 122 mm in the third layer. (ii)Modified compactive effortin five layers so that the compacted height of the soil in the mould is 21 mm to 26 mm in the first layer, 45 mm to 50 mm in the second layer, 67 mm to 72 mm in the third layer, 92 mm to 97 mm in the fourth layer and 117 mm to 122 mm in the f
27、ifth layer. Discard specimens that do not meet these requirements. (e)Free the material from around the inside of the collar and carefully remove the collar. (f)While the baseplate is still attached, trim the surface of the compacted specimen level with the top of the mould by means of a straightedg
28、e. Use smaller size material to patch any holes developed in the surface from removal of coarse material during trimming (see also AS 1289.5.1.1 or AS 1289.5.2.1). (g)Remove the perforated baseplate, spacer disc and filter paper, and determine the mass of the mould plus compacted soil (m2). (h)Place
29、 a filter paper on the perforated baseplate, invert the mould plus the compacted soil and place it on the baseplate. Clamp the baseplate to the mould with the compacted soil in contact with the filter paper. (i)If soaking is not required, perform the penetration test (see Clause 8). 7SOAKING THE TES
30、T SPECIMENSoak the test specimen as follows: (a)Determine the mass of the baseplate plus mould plus specimen (m3). (b)Place the stem and perforated plate on the compacted soil specimen in the mould and apply surcharges of 4.5 kg. Apply any additional surcharges, if specified (see Note 8). (c)If meas
31、urement of swell is required proceed as follows: (i)If the tripod and or measuring gauge is to be removed from the mould during soaking, set the reading on the measuring device against the setting piece. (ii)Record the initial reading before soaking (h1) using the metal tripod and displacement measu
32、ring device. Mark the points of contact of the tripod with the mould. (d)Immerse the surcharged specimen in water, allowing free access of water to the top and the bottom of the specimen. Allow the specimen to soak for 4 days, or for the specified soaking period (see Note 9). Maintain the water leve
33、l above the mould during this period. (e)After soaking is completed, if the measurement of swell is required proceed as follows: (i)If the tripod or measuring device has been removed from the mould during soaking, set the reading on the measuring device against the setting piece so that it is the sa
34、me as that used in Step (c); COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 7AS 1289.6.1.11998 (ii)Place the tripod on the points of contact marked in Step (c) and record the reading after soaking (h2). (f)Tilt the specimen to remove the surface water. Return the mould to the vertic
35、al position and allow the specimen to drain downward for 15 min. Do not disturb the surface of the specimen during the removal of water. (g)Remove the surcharges, stem and perforated plate and determine the mass of the baseplate plus mould plus specimen (m4). (h)Perform the penetration test (see Cla
36、use 8) as soon as practicable ensuring the specimen does not dry out. 8PROCEDUREThe penetration test shall be performed on the end of the compacted specimen which was in contact with the spacer disc during compaction. The procedure shall be as follows: (a)Place the 2.25 kg annular surcharge on the s
37、oil surface and then place the mould plus specimen plus baseplate in the loading machine. Seat the penetration piston with the smallest possible load (see Note 10), 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
38、 as required (see Note 8). Unless otherwise specified the surcharge mass shall be 4.5 kg. If the specimen was soaked, apply surcharges equivalent in mass to those applied during soaking. (b)Read, or set to zero, the force-measuring device and the displacement measuring device used to measure penetra
39、tion. The penetration measured shall be that of the piston relative to the mould (see Note 11). (c)Apply the load with a constant rate of penetration 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 12 and 13). (d)Remov
40、e the soil from the mould and determine the moisture content of the top 30 mm layer (w30) and, if required, that of the remaining specimen (wr) in accordance with AS 1289.2.1.1. 9CALCULATIONSThe calculations shall be as follows: (a)Plot the load-penetration curve (see Figure 6). When the load-penetr
41、ation curve is concave upward initially (because of surface irregularities or other causes) adjust the zero point as shown in Figure 6, curve 3. 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
42、 if required, the force value in kN at penetrations of 2.5 mm and 5.0 mm and calculate the bearing 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. (c)Calculate the dry density of th
43、e specimen before soaking ( d) from the following equation: . . . 9(1) where d = dry density of the specimen, in grams per cubic centimetre m2= mass of the mould plus compacted soil, in grams COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.6.1.119988 m1= mass of the mould, in
44、 grams V1= volume of the specimen before soaking, in cubic centimetres (volume of the mould less the volume occupied by the disc) w1= moisture content of the material immediately prior to compaction (d)If the specimen is compacted to a density ratio other than 100 per cent, calculate the laboratory
45、density ratio (LDR) of the specimen from the following equation: . . . 9(2) where LDR= laboratory density ratio, in percent d = dry density of the specimen, in grams per cubic centimetre MDD = maximum dry density of the soil, in grams per cubic centimetre (e)If the specimen is compacted with a moist
46、ure ratio other than 100 percent, calculate the laboratory moisture ratio (LMR) of the specimen from the following equation: . . . 9(3) where LMR = laboratory moisture ratio, in percent w1= moisture content of the soil immediately prior to compaction, in percent OMC = optimum moisture content of the
47、 soil, in percent (f)If the swell is to be measured, calculate the swell (S) from the following equation: . . . 9(4) where S= the swell of the specimen, in percent h2= the reading after soaking, in millimetres h1= the reading before soaking, in millimetres (g)If the specimen has been soaked and if r
48、equired, calculate the mass of dry soil in the specimen (m5) from the following equation: . . . 9(5) where m5= mass of dry soil in the specimen, in grams m2= mass of mould plus compacted soil, in grams m1= mass of mould, in grams w1= moisture content of the soil immediately prior to compaction, in p
49、ercent COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 9AS 1289.6.1.11998 (h)If the specimen has been soaked and if required, calculate the moisture contentof the specimen after soaking (ww) from the following equation: . . . 9(6) where ww= moisture content of the specimen after soaking, in percent w1= moisture content of the soil immediately prior to compaction, in percent m4= mass of mould baseplate plus mould plus specimen after soaking, in grams m3= mass of mould baseplate plus mould plus specimen before soaking, in grams m5= mass of dry s
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