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DPL OPERATION PRINCIPLE1.1 Traditional DPL
A DPL apparatus operates with a 10 kg weight, dropheight 50 cm, generating the energy of 50 kJ todrive rods and cone to 12 meter depth. The cone,massive, of diameter d = 35.7 mm, tip angle 90 andcross section 10 cm, admits to capture resistance in-formation of the soil.
1.2 DPL NILSSON
The Brazilian modified DPL system, known as DPLNILSSON is an upgraded modification of the tradi-tional DPL, improved by torque measurements toregister lateral cone friction. After every meter of
penetration, before a new rod is connected, a torquetest is made. The DPL NILSSON apparatus is non-motorized, easily dissembled in smaller parts, lightand easy to transport and operates with high effi-ciency. One assembly staffed by 2 or 3 persons canadvance 50 to 60 meters per day.
1.3 Comparisons
Compared with other field tests, DPL is light andeasy to transport. The complete equipment weightsless than 100 kg and can be transported in a smallcar. It is possible to install in small and narrow lo-cals, and is environment friendly. A great vantageobtained by the design is the clearly defined geome-try and constant mass which qualifies the cone as adiscreet, measurable object. Different from a sam-
pler, the DPL cone is massive and cannot contain air,
water or soil, so objective resistant measure is possi-ble.
Figure 1. DPL NILSSON apparatus on campaign at Indaia-
tuba/SP, Brazil.
Parameter approach from DPL test
Thomas NilssonB.Sc. Civil Engineering, M.Sc., Brazil
www.nilsson.com.br
ABSTRACT: The article presents approaches and collections of geotechnical parameters from the port-able field test apparatus DPL NILSSON, manually operated by two persons. The raw parameters are ob-tained by blows and torque test. Some of the obtained geotechnic parameters for dimensioning are tip resis-tance, side friction, compacity and consistence. Significant vantages by this equipment is access to remotesites, high production, transport, low cost and positive ecological aspects..

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Figure 2. Comparison in proportional scale betweenSPT-sampler, DPL cone and CPT-cone.
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PRIMARY PARAMETERS2.1 Obtained parameters
The prime raw parameter, obtained from any DPLtest is N10= blows to advance 10 cm. The DPL
NILSSON test include torque on the assembled rodsand cone. Mmaxis the maximal obtained moment,captured instantly before soil rupture, and Mresis theaverage residual moment on the continuous rotationafter rupture.
2.2 Tip resistanceThe modified Hiley equation (Thomas Nilsson)gives:
21
22
11
2 mm
mem
ss
hgmakP
elpl
f+
+
+
= (1)
where Pf = tip force; k = correction factor to coverenergy deviation, a = hidraulic correction factor, m1
= weight of hammer; m2 = weight of rods, anviland cone; g = earth gravity; h = fall height of ham-
mer; spl= plastic soil displacement; sel = elasticdisplacement of equipment and soil; e = coefficientof impact.
fA
Pq
c
f
c = (2)
where qc= tip resistance of cone; Ac = cross sectionarea; f = lateral resistance.
2.2 Lateral resistance
The vertical aligned surface of the cone has the sameheight as diameter, the nominal contact area withsoil = 5D2/4. For DPL NILSSON, the theoretic ob-tained area of soil contact, 50cm should be in-
creased to 60cm, as the upper side of the cone hassome soil contact.
The lateral resistance is obtained by the equation.
LA
Mf
= (3)
M = Moment, L = moment lever.
A = Cone surface area in contact with soil
The lever is d / 2 for the lateral section and d / 2for the tip section. The resultant moment lever can
be approached to 16mm. Approach the product ALto 100 (cm x cm), f = 10M.moment in Nm, AL inm x m and f in kPa.
The interface friction between the cone (steel tosoil) is supposed to be less than the inner shear resis-tance of the soil so the received value of f can beused as a safe measure of soil shear resistance.
Figure 3. Raw parameters from DPL NILSSON test: Table
and graph of blows N10, graph of lateral resistance f, and graphof tip resistance qc.

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3 PROJECT PARAMETERS
3.1 Source
The parameters are acquired from necessary number
of blows to penetrate a given distance, from neces-sary moment to rotate the cone and from soil andwater print on extracted rods .
3.2 Cohesion and friction angle by DPL NILSSON
The shear resistance can be estimated by DPL sidefriction, as earlier shown. As expressed by Mohr, itis composed by cohesion and friction angle.
tan'+= cfu (4)
If the soil contains > 40 % clay, it can be consideredas a cohesive soil. If > 75 % sand, it should be con-sidered as a friction soil.
Joseph Bowles relates the interface friction angle be-tween metallic surface and soil = 14 to 22 forfine to coarse sand, and = 11 for silt. That is ap-
proximately 15 less than the ordinary interior fric-tion angle of the soil.
Suppose a torque test in clay, the shear resistance ismastered by cohesion. The cohesion of the soil
should be higher than the measured lateral frictionbetween the smooth cone surface and the surround-ing soil, so consider c > f.
DPL test in sand is governed by the friction angle.Approaching cohesion to zero, the estimated frictionangle can be expressed by the formulae:
'019.0
>
f (5)
where is the soil tension and f is the measured side
friction.
3.3 Allowable load
The resistance value derived from pile driving for-mulas by Bolomey, 1974, gives the Dutch equation:
eAMsS
HMrd
+
=
)(
2
(6)
where M = weight of the hammer; S = weight of the
extension rods; s = length of the extension rods; H =height of fall; A = cone cross section area; e = aver-age penetration/blow.
For DPL of standard dimension, this equation can beexpressed as a second degree equation, with rdgivenas a function of the penetration of the driven rods:
102 )44,006,0003,0( Nssrd += (MPa) (7)
Table 1. Obtained values, applying the Dutch equation downto 5m._________________z r
d
m MPa_________________1 0.35N102 0.29N103 0.25N104 0.22N105 0.20N10_________________
In Procedimentos de Sondeos, Jesus Puy Huarte,recommend the allowable load, for footings:
20d
adm
r
= (8)
For piles:
612d
admd rr
83 Dense___________________________
4.2 Blows vs. consistence
For classification of consistence in cohesive, unsatu-rated soils, with Plastic Index under medium value,the following table is extracted from the Germanstandard DIN 4094.

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Table 3. Consistence of finesoils evaluated from DPL___________________________Blows Consistence
N10___________________________< 3 Very soft3 - 6 Soft6 - 12 Medium13 - 22 Stiff23 - 45 Very stiff
> 45 Hard___________________________
A soil of N10< 7 blows needs a special attention inthe project, such as bypass with piles, reinforcementof the soil or other kind of geotechnical engineeringsolutions. Soils with N10over 80 blows do generallyhave medium to high resistance.. Soils with N10 from3 to 25 are normally easy to excavate.
5 CONCLUSIONS
The number of blows N10of DPL allows quick ap-proaches of some soil characteristics like resistance,consistence and compacity. From torque tests in theapparatus DPL NILSSON, parameters as frictionangle and cohesion can be roughly estimated.
In the choice between expensive and simple tech-nology, some equipments of simple technology givesa positive cost-benefit rate by low operation costs,high test velocity, easy transportation, access to dif-ficult locals and fast interpretation. The technicalquality is rather a function of project, raw materialand manufacturing than of complexity and hi-tech.
The service quality depends on compatibility withavailable labor, access, environment and control.Field campaigns are subjected to rude conditions anddepend a lot on logistics. A portable equipment likeDPL equipment fits good under such conditions.
6 REFERENCES
Bergdahl U., Ottoson E. 1988. Soil Characteristicsfrom penetration test results, Proc ISOPT-1, Or-lando, USA.
Bolomey, H 1974. Dynamic Penetration Resis-tance Formulae. Proc European Symposium on
Penetration TestingVol 2:2, Stockholm 7p.
Bolton,M 1979,A guide to soil mechanics,Macmillan Press, London, UK.
Bowles, J.1986. Engineering Properties of Soils andTheir Measurement
Cunha, R, Nilsson. T. 2004. Advantages andequations for pile design in Brazil via DPL tests,ICS
2004, Porto/ Portugal, 20-25 de Setembro de 2004,7p.
DIN Taschenbuch.1991. Erkundung und Unter-suchung des Baugrunds. Beuth
Ireland, H.O. , Moretto, O and Vargas. M. The Dy-namic Penetration Test: A Standard that is not stan-
dardized. Geotechnique, Vol 20, 7pISSMFE 1989. International reference test proce-dures for dynamic probing (DP). Report of the ISS-
MFE Technical Committee on Penetration Testingof Soils TC 16 with Reference Test Procedures.Swedish Geotechnical Society, 49p.
Jesus Puy Huarte. 1977. Procedimentos de Sondeos,teora, prctica y aplicaciones. Publicaciones cienti-
ficas de la Junta de Energia Nuclear, Madrid. 549p.
Massarsch, R. , Lindholm, P, Mrtensson, O. 1976 .Ny ltt sonderingsmetod. (New Light Penetrationtesting Method).Royal Institute of Technology, JO

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