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1、1AS 1289.6.5.11999 Australian Standard Methods of testing soils for engineering purposes Method 6.5.1: Soil strength and consolidation testsDetermination of the static cone penetration resistance of a soilField test using a mechanical and electrical cone or friction-cone penetrometer 1SCOPEThis meth
2、od applies to the determination of the static cone penetration resistance of a soil in the field, using a cone penetrometer, and additionally the sleeve skin friction and friction ratio of a soil in the field, using a friction-cone penetrometer (see Note 1). 2APPARATUSThe following apparatus shall b
3、e used: (a)PenetrometerA penetrometer, similar in general features to the type illustrated in Figures 1 or 2. The penetrometer point shall be a cone of 60 2 degrees point angle, and a base diameter of 35.7, +0, 0.4 mm, resulting in a projected area of 1000 mm2. The cone shall be made from steel of a
4、 type and hardness to resist wear due to abrasion by soil, and shall have a surface finish equivalent to a ground-machined surface. Periodically check the dimensions of the cone and replace it when the dimensions no longer meet the specifications above. As the method permits a variety of penetromete
5、rs to be used, the main features of each type are as follows: (i)Simplified cone penetrometermechanicalFigure 1 shows the design of a typical simplified static cone penetrometer. The push rod is connected directly to the cone with the diameter of the push rod being about 8 mm less than that of the c
6、one. (ii)Cone penetrometermechanicalFigure 2 shows the design and action of a typical static cone penetrometer. A mantle of reduced diameter is attached above the cone, to minimize soil contamination of the sliding mechanism. This mechanism shall permit a downward movement of the cone, in relation t
7、o the outer sleeve, of a least 40 mm. (iii)Friction-cone penetrometermechanicalFigure 3 shows the design and action of a typical mechanical friction-cone penetrometer. The lower part of the tip, including a mantle attached to the cone point, advancesfirstuntilthefrictionsleeveandthenbothadvance.This
8、 mechanism shall permit a downward movement of the cone in relation to the outer sleeve of at least 40 mm in each phase. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 AS 1289.6.5.119992 The friction sleeve shall have the same outside diameter as the base diameter of the cone, viz 3
9、5.7 +0.5 0 mm. No other part of the penetrometer shall project outside this diameter. The surface area of the sleeve shall be either 10,000 mm2or 15,000 mm21 percent. The sleeve shall be made from steel with a smoothness equivalent to a ground machined surface. Periodically check the dimensions of t
10、he sleeve and replace it when it no longer meets specification. (iv)Cone penetrometerelectricalFigure 4 shows a typical design for an electrical cone penetrometer tip. The cone resistance is measured by a force transducer fitted to the cone. (v)Friction-cone penetrometerelectricalFigure 5 shows a ty
11、pical design for an electrical friction-cone penetrometer tip. The friction force on the friction sleeve is measured separately from the cone resistance. An electric cable transmits the transducer signals to the surface data acquisition system. (b)Rod assemblyThe rods shall be of material and sectio
12、n adequate to sustain the maximum load from the thrust machine or to advance the cone, as applicable, without buckling in an unsupported length of 1.5 m. (see Note 2). The rod assembly for the penetrometers shall be as follows: (i)Simplified cone penetrometermechanicalPush rod(s) connected directly
13、to the cone and of sufficient length to penetrate the depth required. The diameter of the rods shall be about 8 mm less than the diameter of the cone. (ii)Coneandfriction-conepenetrometersmechanicalTherodassembly consists of two parts as shown in Figures 2 and 3. The first part consists of a solid i
14、nner rod, which transmits the load from the thrust machine to the cone-plus-friction sleeve. The second part consists of a tubular outer rod with screwed flush joints, which transmits the thrust to advance the complete penetrometer tip. The outer rod, which also provides support for the inner rod, s
15、hall have a constant internal diameter and the rod assembly shall be free of any distortion, so that the clean lightly oiled inner rod is able to move freely inside the outer rod. For a length of at least 1 m above the penetrometer, the external diameter of the outer rod shall not be greater than th
16、e diameter of the base of the cone. The rods shall form a rigid-jointed string and shall have (A)a smooth surface; (B)a constant external diameter; (C)screwed flush joints; (D)a continuous straight axis; and (E)a length the same as the outer rods 0.1 mm. The radial clearance between the inner and ou
17、ter rods shall be between 0.5 and 1.0 mm. (iii)Cone and friction-cone penetrometerselectricalElectrical penetrometers require only tubular push rods with an internal diameter sufficient for passage of the electrical measuring cable, where this is used. The rods shall be of material and section adequ
18、ate to sustain the maximum thrust of the machine, without buckling in an unsupported length of 1.5 m. The external diameter of the rods shall be no greater than the diameter of the base of the cone for a length of 1 m above the base. The rods shall have screwed flush joints and form a rigid-jointed
19、string with a continuous straight axis (see Figures 4 and 5). COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 3AS 1289.6.5.11999 (c)Measuring equipmentThe applied thrusts may be measured by any suitable device (e.g. a load ring, an hydraulic or electric load cell). The equipment shal
20、l measure the thrust to an accuracy of 2 percent of the mechanical thrust or 200 N, whichever is the greater. The outputs from the electrical force transducers may be read and recorded by suitable devices. The equipment shall have an accuracy of 2% of the maximum force or 200 N, whichever is the gre
21、ater. It has been found convenient to obtain continuous penetration records on a strip chart recorder. (d)Thrust machineThe thrust machine shall be capable of forcing the penetrometer and rod assembly into the soil at a constant rate and with a continuous stroke over a distance greater than one rod
22、length. Deep penetrometer soundings usually require a thrust of at least 45 kN, and some machines have capacities in the range of 100 to 200 kN.Acapacityof100 kNshouldbeadequateforallbutexceptional circumstances. The machine shall be fitted with a suitable rod guide at its base, to prevent significa
23、nt bending of the rods between the machine and the ground surface (see Note 3). The machine shall also be provided with some means of measuring depth of penetration, such as a graduated metre rule mounted adjacent to the rod assembly. (e)Reaction equipmentAdditional reaction in excess of that provid
24、ed by the mass of the thrust machine is usually required (see Note 4). (f)Friction reducer (optional)The most common form of friction reducer is a rod with an enlarged diameter, fitted into the string of rods near the penetrometer tip (see Note 5). (g)SpacersIf the test is carried out inside a cased
25、 borehole, suitable spacers shall be provided to prevent buckling of the rods (see Note 3). FIGURE 1TYPICAL SIMPLIFIED CONE PENETROMETER COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 AS 1289.6.5.119994 DIMENSIONS IN MILLIMETRES FIGURE 2TYPICAL MECHANICAL-TYPE CONE PENETROMETER DIME
26、NSIONS IN MILLIMETRES FIGURE 3TYPICAL MECHANICAL FRICTION-CONE PENETROMETER COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 5AS 1289.6.5.11999 FIGURE 4 TYPICAL ELECTRICAL CONE PENETROMETER COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 AS 1289.6.5.119996 FIGURE 5TYPI
27、CAL ELECTRICAL FRICTION-CONE PENETROMETER COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 7AS 1289.6.5.11999 3PROCEDURE 3.1GeneralPenetrometer tests require careful attention to detail, if reliable results are to be obtained. The most important precautions are outlined in Note 6. The
28、 general assembly details for the penetrometers are as follows: (a)Set up the thrust machine for a thrust direction as near vertical as practicable. (b)Connect the penetrometer and the first length of rod assembly, and place them in the thrust machine, inserting the penetrometer in the rod guide at
29、the base of the machine. (c)Where the test is being carried out in a cased borehole, connect sufficient lengths of rod assembly for the penetrometer to reach the soil surface. Add spacers at 1.5 m intervals for lateral support. (d)Advance the penetrometer to the required level by applying sufficient
30、 thrust to the outer rods. The rate of penetration is not critical for this operation. Record the test level or depth. For electrical devices, allow the tip of the cone to remain in this position until it has reached ground temperature. A period of 5 to 10 min should normally be sufficient. Withdraw
31、 the penetrometer and take initial readings of the electrical transducers, with the penetrometer hanging freely in air and protected from sunlight. Advance the penetrometer to the recorded test level or depth. 3.2Simplified cone penetrometerForce the cone into the soil to the full extent of its trav
32、el at a constant rate of 10-20 mm/s, by applying thrust to the rod. Record the load reading at specific points in the travel and the depth of the point of the cone (See Note 7). 3.3Cone penetrometerThe procedure shall be as follows: (a)Force the cone into the soil to the full extent of its travel at
33、 a constant rate of 10 to 20 mm/s, by applying thrust to the inner rod. Record the load reading at specific points in the travel and the depth of the point (see Notes 7 and 8). (b)Force the outer rod down behind the cone and take a second reading of force (see Note 9). (c)Continue thrusting on the o
34、uter rods and take a third reading of force as the collapsed penetrometer tip is advanced to the next test level (see Note 9). Record the new test level or depth. (d)Repeat steps (a) to (c) as penetration proceeds (see Note 7). Once the thrusting mechanism has reached the end of its travel, disconne
35、ct it from the rod assembly, raise the mechanism and insert an additional length of rod assembly. (e)On completion of the test to the required depth, fit the withdrawal mechanism to the rod assembly and withdraw the rods in stages. 3.4Friction-cone penetrometerThe procedure shall be as follows: (a)F
36、orce the cone alone into the soil to the full extent of its independent travel at a constant rate of 10 to 20 mm/s by applying thrust to the inner rods. Record the force reading at a specific point in the travel (see Notes 9 and 10). (b)Continue thrusting on the inner rods, to engage the friction sl
37、eeve and force the cone and friction sleeve into the soil to the full extent of their travel (see Note 9), to give the total cone-plus-sleeve resistance. (c)Force the outer rods down behind the sleeve and cone, to collapse the penetrometer tip and advance it to the next test level. (d)Repeat steps (
38、a) to (c) as penetration proceeds (see Note 7). COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 AS 1289.6.5.119998 (e)Once the thrust mechanism has reached the end of its travel, disconnect it from the rod assembly, raise the mechanism and insert an additional length of rod assembly.
39、 (f)On completion of the test to the required depth, fit the withdrawal attachment to the rod assembly and withdraw the rods in stages until the penetrometer tip is hanging in air. 3.5Final readings for electrical cone penetrometersTake a final set of readings of theelectricaltransducersandcheckthem
40、againsttheinitialreadingstakenin Clause 3.1(d). If this check is not satisfactory for the accuracy required for the test, discard the results and repair or replace the penetrometer tip. 4CALCULATIONSCalculate at any depth the following as applicable to the tests performed: (a)The cone resistance (qc
41、) from the following formula: . . . 4(1)qc= 1000 Fc+ 9.8m where qc= cone resistance, in kilopascals Fc= force on cone alone, in kilonewtons m= mass of inner rods at the test depths, in kilograms (b)Unit sleeve friction resistance (fs) from the following formula: . . . 4(2)fs= (Ft Fc) As 106 where fs
42、= unit sleeve friction resistance, in kilopascals Ft= total force on cone and sleeve, in kilonewtons Fc= force on cone alone, in kilonewtons As= surface area of the friction sleeve, in square millimetres (c)Friction ratio (FR) percent from the following formula: . . . 4(3)FR= fs qc 100 where FR= fri
43、ction ratio, in percent fs= unit sleeve friction resistance, in kilopascals qc= cone resistance, in kilopascals 5TEST REPORTThe following shall be reported as appropriate: (a)Plot or tabulate cone resistance (qc) in kilopascals, vs depth, in metres. Adjacent points may be joined by straight lines (s
44、ee Note 11). (b)Plot or tabulate sleeve friction resistance (fs) in kilopascals, vs depth, in metres, using the same depth scale as in Step (a) (see Note 11). (c)Plot or tabulate friction ratio (FR) in percent, vs depth, in metres, using the same depth scale as in Step (a) (see Note 11). (d)Date of
45、test. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 04 Dec 2007 9AS 1289.6.5.11999 (e)Location of test and identifying number. (f)Reduced level of ground surface. (g)Type of penetrometer used. (h)Type of friction reducer, if used. (i)The number of this Australian Standard, i.e. AS 1289.6.5.1.
46、NOTES ON TEST: 1Static penetrationThe term static is not strictly correct, as measurements are made with the penetrometer moving at a slow, steady rate. However, it is used here to differentiate between slow or quasistatic tests and dynamic penetration tests, where penetration is caused by impact fr
47、om a falling mass. 2Length of rodStandard lengths of XRT drill rods are often used. 3Support of rodsSpecial situations, such as when working over water will require a system of casing support to restrict adequately the buckling of the rods. 4Reaction loadThe following techniques, separately or in co
48、mbination, have all proved successful: (a)Deadload reaction (kentledge). (b)Holding-down frame attached to earth anchors. (c)Mounting the thrust machine on heavy vehicles. The type of reaction provided may affect the penetrometer readings, particularly in the surface or near surface layers. 5Frictio
49、n reducerA special outer rod with an enlarged diameter or projections, called a friction reducer, may be introduced into the string of rods, to increase the maximum depth of penetration for a given total thrust capacity. The location of the friction reducer is governed by the requirements of Clause 2(b). 6Procedural precautions Drift of tipExperience has shown that drift from the vertical alignment can occur where testing is carried out at depths greater than 10 to 15 m. Drift is accentuated by passing through or alongside obstructions and inclined dense
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