6585844961

Australia

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FIG.3

C.R.B. Penetrometer Test Ing Vehlcle

of tha Fugro type penetrometer In sands has been undertaken by HOLOEN (1971), VEISMANIS (1974) and CHAPMAN (1974).

The thrust machlnes malnly comprlse the well-known Dutćhmachlnes (SANOLERAT, 1972, Fig. 6 and 9) of 2,500 and 10,000 kg capaclty and varlous drlll riga.

The Country Roeds Board of Victorla has developed a testlng vehlcle, shown In Figurę 3. Its features include an Army-deslgned, 8-wheel drlve truck; 20,000 kg capaclty; tlltlng loadłng unit; aut ornat ic rod screwing and unscrewlng; and a drl IIIng functlon to borę through hard layers.

5.2    Technięuea

With one exceptlon, all testera penetrate at a ratę In the rangę specified In the proposed A.S.T.M. Standard Method - vlz., 1 to 2 cm/sec.

With the exception of one tester that uses a provlng ring, all use hydraullc load cells to measure the penetration re ais tan ces of mechanical penetrometers.

The pressure gage readlngs at preselected depth lntervals (malnly 15, 20, or 30 cm) are recorded manually and later converted to penetration resistances, which are usually presented graphically as resistance versus depth.

Since 1968, the Country Roads Board of Vlctorla (BARTLETT and HOLDEN, 1988, Discusaions) have recorded the slgnals from thelr electrlcal frlction cone penetrometers with a data logger connected to a chart recorder and a punched paper tape output, The data on tape is then procesaed by a Computer that calculates cone and frlction resistances, frlction ratlo, and cumulatlve skin frlction, and plots the flrst three against depth.

5.3    Use of C.P.T. Results

Most organisatlons that possess quasl-statlc C.P.T. equlpment use the penetrometer as a design tool. It Is used eąually for design (44%) and exploratory purposes (44%) with some use (12%) for the control of malnly compaction processes.

Only four organisatlons calculate the frlction ratlo, for the prime purpose of Indlcating the materiał type.

Apart from thelr important use In extrapolating laboratory test data (obtalned on sampłes taken from a borehole) across a job site, C.P.T. results are used directly In the eslimatlon of (i) (he shear strength of clays for such uses as rough prelimlnary stablllty analyses; (li) ssttlements on sands and also multl-layered deposlts (THORNE and BURMAN, 1968); and (Ili) load capacitle8 of plles. The major references consulted for design methods are the paper by THORNE and BURMAN (1968) and the book by SANOLERAT (1972). Settlements In sands are most accurately determlned uslng the C.P.T. in conjunction with the straln influence factor method proposed by SCHMERTMANN (1970), which appears to be galnlng In favour.

6. OTHER TYPES OF PENETRATION TEST

Mo3t of the other types of penetration tests used in Australia would come Into the category of ^Mcontinuous dynamie tests*. Unforlunately, many of the replles simply stated “Dynamie Cone Test* without glving any detalls.

6.1 Contlnuous Dynamie Tests

There are at least nlne types of contlnuous dynamie test havingdifferent cone diameters, rod slzes, hammer weights and helghts of fali. In many cases, the penetrometer is used simply as a probe to determine the thickness of a soft soli layer or the depth to rock.

The most popular dynamie test for shallow foundatlon investlgatlons is the manuał teBt developed at the Country Roads Board of Vlctoria by SCALA (1958) or the modlfłed verslon descrlbed by GLICK and CLEGG (1965) - see Figurę 4. The callbratlon of the modified Scala penetrometer (ibid.) in a Perth Sand • as charts of penetration resistance (blows/ft) versus relative denslty - fonns the basis for interpreting Its test results.

A test sometimes employed in deep foundatlon inyestigatłons uses the S.P.T. equlpment with a 2 in. (50.8 mm) diam., 60° cone driven in a contlnuous manner from the surface. Applying In-house experience. the test results are often used to estimate