N -values in an adjacent soil boring clearly shows the dense-values in an adjacent soil boring clearly shows the dense ground conditions. Nevertheless, the piezocone sounding was ground conditions. Nevertheless, the piezocone sounding was successfully advanced into these hard residual soils. Note the successfully advanced into these hard residual soils. Note the characteristic negative porewater pressures in the Piedmont characteristic negative porewater pressures in the Piedmont upon reaching the groundwater table.
upon reaching the groundwater table.
When cemented layers, caprock, or hard concretions are When cemented layers, caprock, or hard concretions are encountered in the profile, the CPT sounding can be halted encountered in the profile, the CPT sounding can be halted and the penetrometer can be withdrawn. Then, a rotary drill and the penetrometer can be withdrawn. Then, a rotary drill rig can be set up and used to bore through the cemented zone.
rig can be set up and used to bore through the cemented zone.
The prebored hole can be filled with a backfilled sand or pea The prebored hole can be filled with a backfilled sand or pea gravel and the CPT sounding can be resumed. The backfill gravel and the CPT sounding can be resumed. The backfill helps to stabilize the cone rods and prevent buckling. On helps to stabilize the cone rods and prevent buckling. On completion, the results of part A of the sounding can be completion, the results of part A of the sounding can be
CHA
CHAPTERPTERTWETWELVELVE
CONE
CONE PENETRA PENETRA TION TESTING MODIFIC TION TESTING MODIFICA A TIONS TIONS FOR FOR DIFFICUL DIFFICUL T T GROUND CONDITIONS
GROUND CONDITIONS
FIGURE
FIGURE 9696 SpeciaSpecial Cl CPT dPT deployeployment ment systemssystems::((left left ) single per) single personnesonnel track vehicll track vehiclee(Swede(Sweden),n),((center center ) cherry-picker for urban) cherry-picker for urban access
access(New (New ZealaZealand), nd), andand((right right ) portable ) portable unit for unit for arctic workarctic work(Canada).(Canada).
FIG
FIGURE 97URE 97 SpeSpeciacial CPT del CPT deploploymeyment bynt by((left left ) air) airboaboat,t,((center center ) bar) barge, ange, andd((right right ) New Orleans marsh buggy.) New Orleans marsh buggy.
FIGURE
FIGURE 9898 CompoComponents onents of portaf portable reble remotely motely operaoperated drted drillill(PROD)(PROD)::((left left ) 3000-m-lon) 3000-m-long umbilical g umbilical cable,cable,((center center ) remote control) remote control panel and data acq
panel and data acquisitiuisition,on,((right right ) CPT and rotary drill platform.) CPT and rotary drill platform.
78 78
FIGURE 99
FIGURE 99 QuestiQuestionnaionnaire responsre responses concernes concerning major obsting major obstacles to use of CPT.acles to use of CPT.
s Heavy 20-Ton Deadweigghtht
C
CPPT TrT Truucks and Track Ricks and Track Riggss
Mayne
Mayne et et al. al. (1995) (1995) Increased Increased weiweigght reaction overht reaction over standard drill ri
standard drill rigg Friction Red
Friction Reduucer cer van van de de Graaf Graaf and and Schenk Schenk (1988) (1988) Effective Effective in in frictiofrictional nal soilsoils, s, bbuutt not so
not so in very dense sandsin very dense sands Cyclin
Cyclinggof Rods (of Rods (uup p and and down) down) Shinn Shinn (1995, (1995, personalpersonal comm
commuunication)nication)
Local enco
Local encouunter in thin nter in thin hard zoneshard zones of soil
of soil Lar
Largge diameter penetrometere diameter penetrometer (i.e., 44-mm cone; 36-mm
Suupported Inside Larpported Inside Largger 44-er 44-mm Rods;
mm Rods;PPrevents Brevents Buucklincklingg P
Peeuuchen chen (1988) (1988) Works Works well well in in sitsituuationsations involvin
involvinggsoft soils with densesoft soils with dense soils at depth
bentonitic sluurryrry Earth Anchors
Earth Anchors PPaaggani Geotechnical Eqani Geotechnical Equuipmentipment Geoprobe Systems Very Heavy 30- and 40-Ton Ri
Very Heavy 30- and 40-Ton Riggs s Bratton Bratton (2000) (2000) After After larlargge 20-ton rie 20-ton riggarrives atarrives at site, added mass for reaction site, added mass for reaction ROTA
ROTAPP—O—Ouuter Corinter CoringgBit Bit Sterkx Sterkx and and Van Van Calster Calster (1995) (1995) Special Special drillindrillinggcapabilitiescapabilities thro
througugh cemented zonesh cemented zones e
penetration througughhggravels andravels and hard zones Haas (2004); Farringgton andton and Shinn (2006)
Shinn (2006)
Wireline systems
Wireline systems for enhancedfor enhanced access penetrometer system access penetrometer system Adapted and modified after
Adapted and modified afterPPeeuuchen 1998.chen 1998.
NNI
NNI = Nede= Nederlands Normalisatirlands Normalisatie Instie Instittuute; Cte; CPPTWD = cone penetration test while drillinTWD = cone penetration test while drillingg; EA; EAPPS = enhanced accessS = enhanced access penetrometer system.
penetrometer system.
TABLE 14 TABLE 14
SPECIAL TECHNIQUES FOR INCREASED SUCCESS OF CONE PENETRATION SPECIAL TECHNIQUES FOR INCREASED SUCCESS OF CONE PENETRATION IN HARD GEOMATERIALS
IN HARD GEOMATERIALS
added to part B of the sounding to produce a complete depth added to part B of the sounding to produce a complete depth profile. Although this is somewhat unattractive to routine profile. Although this is somewhat unattractive to routine production type CPTs, it
production type CPTs, it does help obtain the desired results,does help obtain the desired results, which include electronic readings of tip stress, sleeve which include electronic readings of tip stress, sleeve fric-tion, porewater pressures, and shear wave velocities. If the tion, porewater pressures, and shear wave velocities. If the geologic conditions of the region normally encounter an geologic conditions of the region normally encounter an embedded hard cemented layer, perhaps the CPT user would embedded hard cemented layer, perhaps the CPT user would
wish to obtain a combine rig (as shown in Figure 102) that wish to obtain a combine rig (as shown in Figure 102) that has capabilities of both static CPT push and rotary drilling has capabilities of both static CPT push and rotary drilling operations.
operations.
The ROTAP tool is specially designed to advance CPTs The ROTAP tool is specially designed to advance CPTs through hard cemented zones (Sterckx and Van Calster through hard cemented zones (Sterckx and Van Calster 1995). Initially, the CPT is advanced in a normal procedure 1995). Initially, the CPT is advanced in a normal procedure
until the hard caprock or concretion is
until the hard caprock or concretion is encountered. Then theencountered. Then the penetrometer is removed and the ROTating AParatus (i.e., penetrometer is removed and the ROTating AParatus (i.e., ROTAP) is installed and used to drill through the hard zone.
ROTAP) is installed and used to drill through the hard zone.
Once through the desired hard layer, the
Once through the desired hard layer, the penetrometer is rein-penetrometer is rein-stalled to continue the sounding.
stalled to continue the sounding.
A special series of Ateliers Mobiles d’Ausultation par A special series of Ateliers Mobiles d’Ausultation par Pénétration des Sols (Mobile Soil Testing Unit by Pénétration des Sols (Mobile Soil Testing Unit by Penetra-tion) static–dynamic penetrometer systems has been tion) static–dynamic penetrometer systems has been devel-oped for testing a range of soft soils to very hard and dense oped for testing a range of soft soils to very hard and dense geomaterials with reported
geomaterials with reported qqccup to 140 MPa (1400 tsf) andup to 140 MPa (1400 tsf) and depths up to 100 m (Sanglerat et al. 1995). A heavy-duty van depths up to 100 m (Sanglerat et al. 1995). A heavy-duty van den Berg track truck is used for the hydraulic pushing. The den Berg track truck is used for the hydraulic pushing. The sounding has three distinct phases: (1) static electric CPT sounding has three distinct phases: (1) static electric CPT push, (2) static mechanical CPT push, and (3) dynamic push, (2) static mechanical CPT push, and (3) dynamic mechanical CPT. The test begins as a standard CPT with mechanical CPT. The test begins as a standard CPT with
either a 44- or 50-cm
either a 44- or 50-cm22 electrical penetrometer (electrical penetrometer (qqcc andand f f ss)) pushed at 20 mm/s until hard static refusal is met at 30 MPa pushed at 20 mm/s until hard static refusal is met at 30 MPa (300 tsf). The sounding is resumed using a 12-cm
(300 tsf). The sounding is resumed using a 12-cm22mechani- mechani-cal cone in static push mode until 120 MPa (1200 tsf) is cal cone in static push mode until 120 MPa (1200 tsf) is reached. To penetrate very dense sands, gravels, rocks, and reached. To penetrate very dense sands, gravels, rocks, and other obstacles, a special dynamic fast-action hydraulic other obstacles, a special dynamic fast-action hydraulic ham-mer is used to advance the cone and, if conditions permit, mer is used to advance the cone and, if conditions permit, resume again with the static push phase. Example results of resume again with the static push phase. Example results of static–dynamic penetrati
static–dynamic penetration in dense sandstone are on in dense sandstone are shown inshown in Figure 103
Figure 103with all three with all three phases of testiphases of testing shown.ng shown.
A sonic CPT system is detailed by Bratton (2000), A sonic CPT system is detailed by Bratton (2000), whereby a vibrator can be intervened when the soil whereby a vibrator can be intervened when the soil resis-tance becomes too great for normal static CPT pushing. The tance becomes too great for normal static CPT pushing. The sonic vibrator is installed in the CPT truck and uses two twin sonic vibrator is installed in the CPT truck and uses two twin 25-hp hydraulic motors with eccentric masses at the top of 25-hp hydraulic motors with eccentric masses at the top of FIGURE
FIGURE 100100 CPT vehCPT vehicles icles for harfor hard groud ground incnd includinluding:g:((left left ) 40-) 40-ton trton truck,uck,((right right ) anchored track rig.) anchored track rig.
FIGURE 101
FIGURE 101 PiezocPiezocone advanceone advanced into very hard partially weathd into very hard partially weathered gneissered gneiss..
80 80
memocone penetrometer is used to store the CPTu data memocone penetrometer is used to store the CPTu data downhole in a memory chip. The system also employs MWD downhole in a memory chip. The system also employs MWD (measurements while drilling) during simultaneous (measurements while drilling) during simultaneous opera-tion of the CPT; therefore, two sets of penetraopera-tion readings tion of the CPT; therefore, two sets of penetration readings are obtained, including piezocone measurements (
are obtained, including piezocone measurements (qqt t ,, f f ss, and, and u
u22), as well as ), as well as the MWD readings of penetration rate, torque,the MWD readings of penetration rate, torque, and fluid pressure. When hard impenetrable layers are and fluid pressure. When hard impenetrable layers are encountered (too hard for CPT), then
encountered (too hard for CPT), then the sounding advancesthe sounding advances strictly on the basis of wireline coring techniques with MWD strictly on the basis of wireline coring techniques with MWD data sti
data still obtaill obtained. Figurned. Figure 105e 105 shows the basshows the basic CPTWDic CPTWD scheme, equipment, and a full set of results of six scheme, equipment, and a full set of results of six measure-ments from a site near Parma,
ments from a site near Parma, Italy.Italy.
An enhanced access penetrometer system (EAPS) is An enhanced access penetrometer system (EAPS) is pre-sented by Shinn and Haas (2004) and Farrington and Shinn sented by Shinn and Haas (2004) and Farrington and Shinn (2006). This is based on
(2006). This is based on a wireline system (Farrington 2000)a wireline system (Farrington 2000) and offers a means to interrupt the CPT steady-state rate of and offers a means to interrupt the CPT steady-state rate of penetration and utilize downhole wireline coring penetration and utilize downhole wireline coring intermit-tently and advance soundings through very dense or tently and advance soundings through very dense or cemented zones or dense or hard geomaterials. The EAPS cemented zones or dense or hard geomaterials. The EAPS also has the ability to take soil samples as needed. Some also has the ability to take soil samples as needed. Some aspects are
aspects are illustrated illustrated ininFigure 106.Figure 106.
Comparative studies of the EAPS deployment and
Comparative studies of the EAPS deployment and normalnormal direct-push technology for CPTs have been made by Applied direct-push technology for CPTs have been made by Applied Research Associates.
Research Associates. Figure 107Figure 107shows four sets shows four sets of super-of super-imposed piezocone soundings at a test site with two
imposed piezocone soundings at a test site with two CPTUsCPTUs produced by the EAPS downhole wireline method (Nos. 2A produced by the EAPS downhole wireline method (Nos. 2A and 2B) and two CPTUs
and 2B) and two CPTUs per normal push methods (Nos. 2Cper normal push methods (Nos. 2C and 2D), with very good agreement seen for all cases.
and 2D), with very good agreement seen for all cases.
FIGURE 10
FIGURE 1022 CombinCombine rig with boe rig with both CPT hydrth CPT hydraulic raaulic rams andms and drilling capabilities.
drilling capabilities.
FIGURE 103
FIGURE 103 AMAP staticAMAP static–dynam–dynamic penetraic penetration system in dense santion system in dense sandstonedstone(after San(after Sangleragleratt et al. 1999).
et al. 1999).
the rods. The vibrations are in the range of 2
the rods. The vibrations are in the range of 25 to 125 Hz and5 to 125 Hz and used to facilitate CPT penetration through dense sands and used to facilitate CPT penetration through dense sands and gravels. Fi
gravels. Figure 104gure 104 shows the sshows the sonic CPT unit onic CPT unit within anwithin an ARA truck.
ARA truck.
A special wireline-based system that combines CPT A special wireline-based system that combines CPT withwith drilling capabilities has been termed CPTWD
drilling capabilities has been termed CPTWD (cone penetra-(cone penetra-tion test while drilling) and is detailed by Sacchetto et al.
tion test while drilling) and is detailed by Sacchetto et al.
(2004). A special modified wireline-type core barrel has been (2004). A special modified wireline-type core barrel has been developed to house the cone penetrometer. An Envi-type developed to house the cone penetrometer. An Envi-type
FIG
FIGURE 1URE 10404 SonSonic Cic CPT syPT system stem witwithh((left left ) deadwe) deadweight truight truck, andck, and((right right ) sonic vibrator unit.) sonic vibrator unit.
FIGURE 10
FIGURE 1055 CPTWD wirCPTWD wirelineeline-based s-based systemystem(Sacch(Sacchetto et al. 20etto et al. 2004).04).
82 82
FIGURE 106
FIGURE 106 EnhanEnhanced access peneced access penetratiotration systemn system(EAPS(EAPS) for penetrati) for penetration of hard geomateon of hard geomaterialsrials(after Farr(after Farrington 200ington 2000).0).
FIGURE 107
FIGURE 107 ComparComparison of CPTUs from standaison of CPTUs from standard push and EAPS wirerd push and EAPS wireline deplline deployed systemsoyed systems(Farr(Farringtonington 2000).
2000).
FIGURE
FIGURE 108108 Jackup Jackup rigs forigs for nearr nearshore shore CPT deCPT deploymeployment:nt:((left left ) SeaC) SeaCore, aore, andnd((right right ) The Explorer.) The Explorer.
FIG
FIGURE 10URE 1099 VesVesselsels for offs for offshoshore CPTre CPTs:s:((left left ) Markab) Markab, Austral, Australia;ia;((right right ) Bucentaur, ) Bucentaur, BrasilBrasil(Courtesy: Fugro (Courtesy: Fugro Geosciences).Geosciences).
NEARSHORE AND OFFSHORE DEPLOYMENT NEARSHORE AND OFFSHORE DEPLOYMENT
On some highway projects, the highway alignment crosses On some highway projects, the highway alignment crosses over a body of water, particularly bridges over rivers or over a body of water, particularly bridges over rivers or streams or waterway canals. The CPTs can be mobilized to streams or waterway canals. The CPTs can be mobilized to conduct soundings from floating barges. In swampy coastal conduct soundings from floating barges. In swampy coastal areas with shallow water, movable pontoons are used that are areas with shallow water, movable pontoons are used that are floated empty to their location, then filled with water to floated empty to their location, then filled with water to
pre-pare a working platform for the CPT truck or rig. In pare a working platform for the CPT truck or rig. In nearshore environments, highways may follow the coastal nearshore environments, highways may follow the coastal shoreline or connect small islands and land masses. In these shoreline or connect small islands and land masses. In these cases, the use of a jackup rig may be warranted. Figure 108 cases, the use of a jackup rig may be warranted. Figure 108 shows two jackup-type platforms in use for drilling, shows two jackup-type platforms in use for drilling, sam-pling, and CPT works. If water depths are
pling, and CPT works. If water depths are greater than 15 m,greater than 15 m, then a special CPT ship can be
then a special CPT ship can be deployed to conduct offshoredeployed to conduct offshore site investigations (Figure 109).
site investigations (Figure 109).
Cone penetration technology can assist the geotechnical Cone penetration technology can assist the geotechnical highway engineer in the collection of site-specific soils highway engineer in the collection of site-specific soils infor-mation in a cost-effective, quick, and reliable manner. From mation in a cost-effective, quick, and reliable manner. From a practical standpoint, the cone penetration test (CPT) a practical standpoint, the cone penetration test (CPT) sound-ings obtain continuous logging of the soil layers and ings obtain continuous logging of the soil layers and stratig-raphy. In many cases, the CPT outperforms the normal and raphy. In many cases, the CPT outperforms the normal and conventional rotary drilling and sampling operations in the conventional rotary drilling and sampling operations in the field and the associated laboratory testing that can take weeks field and the associated laboratory testing that can take weeks to produce results. However, the two methods can be to produce results. However, the two methods can be com-plementary, with the CPT providing immediate profiling of plementary, with the CPT providing immediate profiling of the subsurface conditions and follow-up confirmation and the subsurface conditions and follow-up confirmation and select verification by the boring, sampling, and lab testing Canadian departments of transportation (DOTs) to survey Canadian departments of transportation (DOTs) to survey the
thestate of the practice in highway site invesstate of the practice in highway site investigations relevanttigations relevant to use of the CPT. With a total of 56 DOTs responding, to use of the CPT. With a total of 56 DOTs responding, 63%
63%indicated that they weindicated that they were using the CPT on their re using the CPT on their projectsprojects to some degree; the remaining 37% of the respondents to some degree; the remaining 37% of the respondents indicated no use of the CPT whatsoever in their state or indicated no use of the CPT whatsoever in their state or province. Therefore, the CPT appears to be underutilized at province. Therefore, the CPT appears to be underutilized at present for highway projects in the United States and Canada.
present for highway projects in the United States and Canada.
On a positive note,
On a positive note, 64% of the respondent DOTs did foresee64% of the respondent DOTs did foresee an increase in the probable use of this technology on future an increase in the probable use of this technology on future highway projects.
highway projects.
CPT capabilities include the direct assessments on the CPT capabilities include the direct assessments on the geostratigraphy, with detailed demarcation on the numbers, geostratigraphy, with detailed demarcation on the numbers, depths, and thicknesses of soil layers; presence of depths, and thicknesses of soil layers; presence of interbed-ded lenses; groundwater table(s); and relative hardness of the ded lenses; groundwater table(s); and relative hardness of the various strata in the subsurface environment. These various strata in the subsurface environment. These sound-ings are recorded and stored digitally and
ings are recorded and stored digitally and thus can be quicklythus can be quickly
ings are recorded and stored digitally and thus can be quicklythus can be quickly