6585844930

119

Sweden

100 kg y

ROTATED MANOLLY OR BY HACHINE

7T

SCREW POINT'

o)WEIGHT SOUNDING

b)STATIC SOUNDING

METHOD A METHOD B (OETAILEO ISIMPLE TEST I    TEST )

re results from dlfferent borę holes and to use the results as a basis for design.

The requests of standardizatlon of exist1ng sounding method Increased during the latter part of the 1950th when the number of geotechnlcal consulting firms Increased rapldly 1n Sweden. It was therefore timely that an International commlttee on penetratlon testlng was appolnted by the 4th International Conference on Soli Kechanics and Foundation Engineering 1n London 1957, and that the main task of this commlttee was standardizatlon of dlfferent sounding methods.

In 1958 the Swedish Geotechnlcal Society (SGF) appolnted a Swedish commlttee on penetratlon testlng. The nine members 1n this national commlttee represent State and local authorities, geotechnlcal consultants and manufacturers of geotechnlcal equ1pment.The main tasks of the commlttee were standardizatlon of existing sounding methods 1n Sweden and deve1opment of new or improved methods when existing methods were not adequate. An additional task of the commlttee was mechanization of ex1sting sounding methods. Comparat1ve tests with dlfferent sounding methods and 1nvestigat1ons of the influence of dlfferent factors on the penetratlon resls-tance have been initiated by the committee. Sounding methods used abroad have also been tested and compared with Swedish methods. Parts of this research has been carrled out at the Swedish Geotechnlcal Institute and at the Geotechnlcal Department of the Royal Institute of Technology in Stockholm.

The present work of the commlttee 1s mainly con-centrated on the following problems

1)    standardlzation of static sounding and of soil-rock sounding methods

2)    calculation of settlements and bearing capacity of pile groups and of footings founded on grave1, sand or coarse-grained tlił.

In the very beginning of 1ts work the Geotechnlcal Cornnission of the Swedish State Railways de-veloped and standardized the §tf§dl§b_#ęigb$.$9yQd-iD9.(P£$bQd (Fig.5a).The modlfications in the later standard of 1970 are primarily due to the mecha-nization of the method during the last few years.

Push sounding refers to a light penetratlon testTńg’metfiod where the welght sounding rods and the screwpoint are pushed down by hand in-stead of with weights.

Dlfferent ram sounding methods were used very early in Sweden as mentioned above. About 1940 most of these were replaced by the Swedish ram sounding method, developed by the Swe3TśR’?Trm §5rr5s‘A§“[F?g7 5c). This method was standardized In 1963 and has recently been 1mproved (Bergdah! & Dahlberg, 1973). The improved procedurę, method A, is morę comprehensive in comparison with the traditional method, deslg-nated method B, in the current standard of 1971.

OT RESULTS PLOTTEO AUTOMATIC A LLY (ElECTRICALLY OR MECHANICALLY ORIYEN RECOROER )

!Cgwrar-*r*rr^l •'

Ą ^% aloc

1 ®LOC

c)RAM SOUNOING d)LIGHT MOTOR e)SOIL-ROCK

PERCUSSION SOUNDING SOUNDING

Fig. 5

Princlple of some conwon Swedish sounding methods.

When the Swedish Geotechnical Institute (SGI) was founded in 1944 a new period of expans1on was started in the geotechnical engineering field 1n Sweden. During 1944-1955 dlfferent kind of samplers, the vane borer and a static sounding machinę were deve1oped.With the SGI static sounding machinę designed in 1950 {RaTTitenTuśT iSSTrtfie point resistance is plotted automatically as a function of depth.

Since 1950 several Swedish engineering companies have developed static penetrometers with mecha-nically or electrically driven recorder units which automatically plot the penetratlon resistance as a function of depth.

About 1955 the firm Jonell & NilssonABfnow N11-con AB) developed a meęhanical_stątic_sounding deyice which is rather"TńexpeniTve7’It’wai’ tfierefore used extensively from the very be-ginnlng. The total penetratlon resistance (Q_T) is recorded continuously with this device, but the skin frlction component (Q_s) only at 1ntervals. The point resistance is taken as the difference (Q_T - Q_$) (Fig. 5b).

Borros AB has developed an electrical penetro-meter which measures the point resistance by strain gauges. Geotech AB has recently presen-ted (Jonell, 1973) an acoustical penetrometer,