USERS MANUAL NOVA Acoustic CPT SOUNDING
Contents
1. 25 e Tilt e Temperature e Seismic e Electric conductivity 10 cm probes Cone factor a 0 82 Sleeve factor b 0 0 Digital From probe to surface RW 17 Acoustic 17 bit or by cable 17 bit resolution e with RW and acoustic data transmission 10 cm probes 4 alkaline type C batteries 8 hours e with cable data transmission via the cable e Back up memory of CPT data in cone 18 bit resolution e Alarm and emergency stop of push triggered by a preset maximum point resistance or tilt increment e Mud lubrication of rods to reduce mantle friction e CPT CPT LOG Windows software running on PC notebook e SCPT SCPT DAA Windows XP Vista software on PC notebook e CPT CPT PRO by Geosoft Geotech agent in Poland Demo version at the Geotech site e CPT CONRAD by the Swedish Geotechnical Institute e SCPT SCPT DAA as for the acquisition GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO H TECH 1 2 Detailed part list P N Description 5 27 13595 10755 10757 12451 08875 10662 10660 06975 41540 08871 08527 10785 12425 12428 10513 41380 10702 07629 09485 13595 13596 13598 13599 I Cordless CPT System Minimum Kit Equipment CPT Probe and depth synchronisation Probe 3 channels qc fs u 10 sq cm 50 MPa temperature compensated tilt Depth synchronisation wire Cable depth synchr to interface box Acoustic data transm2. the initial load of the cone resistance and local friction sensor is removed Therefore two zero readings should be taken after the CPT test One with the tip mounted on the probe and one with the tip taken off from the probe 8 SPECIAL APPLICATIONS 8 1 CPT Soundings with cable mode data transmission In CPT soundings where it is preferred to use a cable the same probes depth encoder and interface box are used Needed in addition are e a cable adapter on the probe e cable of sufficient length e an adapter between the end of the cable and the interface box The sound transmitter and microphone are not used The cable is threaded through the extension rods prior to the sounding The two leads of the cable are then connected to the signal conditioning box lead I to socket 1 and lead 2 to socket 2 GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO TECH ve Seismic CPT tests SCPT done with the Geotech seismic CPT adapter can only is run with a cable due to the density of incoming data The data from the other CPTU channels then also transmitted by cable The seismic CPT cable is a shielded cable different from the normal one P N 08870 8 2 Mud lubrication to reduce skin friction along the extension rods Skin friction can be reduced by using a ring of larger diameter on top of the probe so called friction reducer or by pumping approximately lliter of bentonite per push meter By running CPT without a cable the
3. 10 Cable connections Depth encoder wire 2007 6 2 Cables For maintenance purpose or if you need to lengthen the cables in your application the cable connections in the CPT system are as seen here GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH a 6 3 Overload control card The Geotech Overload Control Function is used for CPT soundings with the Geotech cordless Cone Penetration Test CPT system The CPT operator can pre set a maximum point resistance Qc and or tilt increment at which the cone penetration will automatically be halted in order to avoid damaging the probe This can occur when the probe hits a stone or gravel or slants on its side In particular bending of probes can occur within a few centimetres slanted pushing 6 3 1 Mounting Instructions 1 Connections to the penetrometer The overload function is a single pole switch type SPCO which can be used to either close or open an electrical circuit such as an electrically controlled hydraulic valve I e the penetrometer has to have an electrically controlled hydraulic valve to activate the pushdown of the yoke 2 Add extra 2 wire cable to the female contact of the power cable we can supply you with this 3 If the hydraulic flow is stopped by disconnecting the electric circuit i e disconnecting the electrical power to the valve use the pins A and F on the female connector 4 If the hydraulic flow is stopped by closing the ele
4. a support ring washer The support ring has three major tasks 1 To prevent the filter ring to press on the friction sleeve 2 To hold the X ring 3 To prevent the friction sleeve to be pressed downwards and cause damage to the lower X ring during the pull back after each test At this lower end of the probe the point with the filter ring is mounted The pore pressure sensor is located inside the cone resistance sensor The cavity between the pore pressure sensor and filter ring pore pressure chamber and the filter ring should be saturated with liquid to have the necessary response All sensors are arranged on the probe in order to minimise the influence between the sensors To obtain repeatable results it is very important that the O rings seal for water and the X rings for soil Therefore all sealing in the probe are set under initial stress If not they will not seal In addition O ring sealing will always leak if damaged or dirty When replacing O rings lubricate with Vaseline and mount the friction sleeve carefully Because of tolerances in the manufacturing procedure of the CPT probe the friction response should always be checked when the friction sleeve is replaced GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH aen 7 3 Zero readings After each test in the field and after the probe has been pulled out from the ground the zero values of the sensors should be compared with the zero values taken before
5. inner diameter of the extension rods can be used for pumping down bentonite Total push force tonnes o 5 10 Oo T Bentonite is prepared in the reservoir of a mud pump which is connected with a hose to the mud adapter of the CPT microphone The pump is activated as the test is started The resulting reduction in skin friction is illustrated in Fig 11 where a reaction force of 8 tons is reduced by 50 at 18 n depths N Oo Refusal at18m Depth below surface m 8 T gt Oo Stop push 45m No refusal Figure 11 Reduction of reaction force in CPT sounding by using mud lubrication Geotech probe used in the Canadian Beaufort Sea in Lunne et al 1997 50 8 3 CPT Tests in very soft grounds Running CPT in very soft grounds such as in tailings dams it is highly recommended to run CPT test with casing tubes to avoid bending and breaking of rods as the probe would meet more consolidated layers at depth In the absence of skin friction the rods buckle with a load of 5 tons and a rod length of only 1 7 m This is the Euler second formula for rods with both ends able to rotate where Fk w EI and Fi Applied axial force N E Elasticity modulus 22 10 N m I Surface moment of inertia m OD ID 64 m 1 Breaking length m Running CPT with acoustic transmission of data and no cable simplifies the use of casing during testing Casing tubes should be ID 39 mm GE
6. probe characteristics calibration or scaling factors in cpt files abbreviated KQ for point resistance KF for local friction KU for pore pressure O for temperature A for electric conductivity and B for inversion factor for the electric conductivity and checked the zero readings GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO H TECH aan 3 2 Explanations 3 2 1 Deairing Glycerine is recommended rather than water If water is used nonetheless in winter time when temperatures are below zero centigrade it could be necessary to add e g glycol to avoid the water from freezing Control that the filter ring and point are easily mounted on the cone before deairing This will make the mounting easier Boiling The glycerine should be deairated by boiling at least 15 minutes This can be done together with the points and filter rings Take at least as many points and filters that will be used during one day Keep the filters and points in the liquid until they will be used Vacuum treatment Put the points and filter rings in the tank of the vacuum pump Fill the tank with glycerine so that the content is covered Connect the pump and deair for about one hour Be observant so no glycerine is sucked into the pump This could damage the pump If too little glycerine is used it could boil away Keep the filters and tips in the liquid until they will be used Deairing on the site If you have forgotten to deair the tips and fil
7. the motor the hydraulic system and contacts between rod and kelly are not generating undue noise at a sound frequency similar to the sound transmission of the probe This can have detrimental effect on the data transmission during the CPT test At the test site prior to anchoring auger a hole if the top soil consists of a dry crust or if CPTU will be carried out CPT with pore pressure measurement If required anchor the pushing unit and make certain that the pushing will be vertical Mount the depth synchronisation and microphone on the pushing unit Connect power cable microphone cable serial cable and depth synchronisation cable to CPT interface box and notebook Introduce the probe in the funnel and water tight with tape Deair the pore pressure chamber and mount X ring X ring support filter ring and point 10 cm probes 10 cm probes Pre stress the friction sleeve by tightening the cone tip by hand Pull a condom on the probe in particular if water is used in the pore pressure chamber Put fresh C alkaline batteries in the the transmitter Observe that the batteries are installed in the right way with the positive pole facing the probe Mount the probe on the sound transmitter Tighten by hand and not too hard Fill the hole with water Mount the first drill rod on the sound transmitter and start the software Follow the instructions from users manual of the software and start the CPT test after having punched the
8. the test was started If the difference is small for the cone resistance and local friction the conclusion is that it has not been any damage to the sensors and the sealing had worked correctly during the test If there is a difference between the zero readings before and after the test for the cone resistance and local friction it could be caused by the following reasons 1 Overload of the sensors due to high loads or strong bending of the probe 2 The sealing has been leaking Soil between the x rings and the friction sleeve causing higher loads on the ends than the initial load 3 Different temperatures in the probe before and after the test in combination with significant temperature drift in the sensors 4 If the tip for some reason is taken off or just unscrewed a little the initial load on the sensors will also be removed or reduced The zero readings from the pore pressure sensor suffer from a different problem During the pull back after each test sometimes very low pressure can be generated If so the filter ring will drain from liquid and replaced with soil The soil will seal off the pore pressure gauge from the surrounding pressure The result of this is that when the zero readings after test is taken with the tip still on the probe the pressure on the sensor will not be atmospheric To read the correct unloaded pore pressure value zero reading the tip must be removed from the probe However if the tip is removed
9. OTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH In order to reduce the risk of bending and breaking of rods a tilt increment alarm is available in the acquisition software CPT LOG and is defined as degrees per meter A normal triggering value should be approximately 60 degrees meter This function when activated will set the alarm several times each time a new sounding is started before the probe has penetrated the ground For most soils it is recommended to use a friction holder at the foot of the pushing equipment to hold the rods from sinking by their own weight and to fall back in the hole when pulling them up 8 4 Offshore CPT The standard CPT probes and sound transmitters can be used for offshore use The normal water pressure range of the probe is 2 5 MPa i e a 250 m water column The other standard equipment items microphone depth encoder and interface box cannot be placed under water 1 Soundings from boat decks or platforms The standard equipment can be used in a normal way using casing tubes from deck to sea bottom to avoid the bending of rods like in very soft soils 2 Soundings from sub sea platforms In CPT soundings from sub sea platforms generally all rods are assembled prior to the start of the sounding The use of a cordless system does not in such case simplify the operation The microphone and sound transmitter are replaced by a cable connection as under Cable CPT here above The dept
10. Sleeve friction kPa Pore pressure kPa Pore pressure kPa q tr u and uo uand u 0 4 8 12 160 1 2 300 100 0 100 200 300 400 100 0 100 200 300 400 Conventional filter UU Slot filter Figure 7 Example of CPTU sounding run with us filter and grease filled slot filter vacuum is generated at 4 5 m with a conventional filter whereupon is ceases to function The slot filter registers overall larger amplitude variations including lower negative pore pressures Larsson 1995 The slot filter is equipped with a support ring for the X ring and is mounted on the CPT tip The pore pressure chamber is filled with grease as follows 1 Fill the chamber and the inside of the tip with grease Mount the tip and slot filter with an X ring on the cone 3 The chamber and filter become automatically saturated with excess grease squeezed out in the slot GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH 4 No protection has to be taken with the cone as the stiffness of the grease will prevent it from flowing out The choice of grease must be made carefully e With a firm grease zones and layers of unsaturated soil or where negative pore pressures are generated can often be passed without loss of saturation The disadvantage is an evening out of pressure variations e With a softer grease this advantage is lost and the same problems with saturation as with normal fluid saturated filter will oc
11. USERS MANUAL NOVA Acoustic CPT SOUNDING Cone Penetration Testing GEO TECH Ingenjorsfirman Geotech AB E mail support geotech se Datavagen 53 Web site http www geotech se S 436 32 ASKIM Goteborg Sweden Ph 46 31 28 99 20 Fax 46 31 68 16 39 GEOTECH NOVA CPT Acoustic manual 2009 doc 2009 2 27 GEO H TECH TABLE OF CONTENT PAGE 1 1 Probes and Equipment available 4 1 2 Detailed part list 5 Description 5 Description 5 1 3 The Geotech cordless CPT System 6 1 4 Technical data 7 2 EQUIPMENT NEEDED 8 2 1 Checklist 8 2 2 CPT Probe 9 2 2 1 Geotech Probes 9 Description 9 2 3 Sound Transmitter 9 2 3 1 Sound Transmitter for 10 cm probes 9 3 1 Step by step 10 3 2 Explanations 11 3 2 1 Deairing 11 3 2 2 Pre augering 11 3 3 4 Depth Synchronisation Unit DSU 12 3 3 5 Microphone 12 3 3 6 Batteries 13 3 3 7 Saturating the pore pressure chamber and mounting point and filter ring 13 3 3 8 Use of slot type filters 14 3 3 9 Pre stressing the friction sleeve 10 cm probes 15 3 3 10 Other Channels Tilt Temperature and Electric Conductivity 16 3 3 11 Zero Readings 16 3 3 12CPT SOUNDING 16 GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO H TECH 4 USE OF CONES WITH A BACK UP MEMORY 4 1 CPT soundings with cones with a back up memory Data retrieval 5 AFTER THE CPT SOUNDING 5 1 Cleaning the probe 6 INSTALLATION DESCRIPTION 6 1 6 2 6 3 Depth Synchronisation Uni
12. ally 36 x 1000 mm tapered thread Pushing unit penetrometer or geotechnical site investigation rig If required anchoring equipment Logging software CPT LOG GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 9 27 GEO H TECH 2 2 CPT Probe 2 2 1 Geotech Probes Figure 2 CPT Probe 10 cm Item Description P N Item Description P N 1 Point 10 cm 12425 7 O ring 13573 2 O ring 13578 8 O ring 13573 3 Filter ring 41310 9 Friction sleeve 12428 4 X ring 41380 10 Cone body 12427 5 Support ring 12429 11 O ring 13579 6 O ring 13576 2 3 Transmitter 2 3 1 Transmitter for 10 cm probes Figure 5 Sound Transmitter P N 12451 for 10cm probes 11 Serial number of the sound transmitter 12 Batteries 4 pcs C alkaline GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH H 3 3 1 1 10 11 12 PREPARATION FOR CPT SOUNDINGS Step by step Deair points filter rings and grease with vaseline O rings and X rings at the office before CPT tests Keep the probe stored at a temperature as close to the ground temperature 5 C The probes are equipped with a temperature sensor and a microprocessor to compensate for temperature variations Nonetheless the temperature drift is of lt 0 05 FS in the range of 0 40 C for Qc fs and u For a 100 MPa probe Qc range this implies in summer say 45 C a temperature difference of 40 C and a drift 200 kPa Make certain that
13. between the sealing Turn the friction sleeve the right way Wrong way will loosen the cone tip e Ifthe cone tip needs to be dismounted to load the friction sleeve the upper x ring must also be taken off e When loading the pore pressure sensor the other sensors should also be set under the same pressure The reason for this is that crosstalk can be measured so net area factors for local friction and cone resistance can be determined GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH e When loading local friction and cone resistance it is important that the load is applied straight in line to the probe to avoid bending This is for safety reasons and to avoid the influence of bending to the sensors during the calibration procedure The adapters provided by Geotech AB or similar should be used when loading the sensors on the probe 7 2 Sensors and sealing The sensors on the CPT probe are operating in a difficult environment and therefore special demand is required General description of the sensors The friction sleeve is mounted at the lower end of the probe Between the sleeve and the probe is a double O ring sealing to prevent water to leak in under the friction sleeve At both ends of the friction sleeve an X ring is mounted They prevent the soil to act on the ends of the friction sleeve but they are not intended to seal for neither for water nor air The lower X ring close to the filter ring is attached to
14. ctric circuit i e connecting the electric power to the valve use the pins A and B on the female connector When uncertain please send us the electrical circuit diagram of the rig and we will give you a more detailed answer 6 3 2 Use of the overload control card with the CPT logging software The maximum point resistance and tilt increment values are set in the logging software CPT LOG Windows XP Vista When the recorded point resistance or tilt increment value exceeds the pre set values the software goes into PAUSE This gives the operator the choice to stop the sounding or continue at his risk 6 3 3 Recommendations e Maximum point resistance value The cones have a safety factor of 50 Therefore never exceed 25 of the point resistance range e Tilt increment For space reasons the tilt sensor is placed in the electronic part of the probe i e 20 cm from the porous filter Once the probe is introduced in the ground use therefore small tilt increment values in the range of 0 5 cm or 50 m GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOQDTECH 7 Calibration Sensors and Sealing 7 1 Calibration codes Each channel has a calibration code which is a scaling factor amplifying factor for the measured value The calibration code can adopt values from approx 400 up to 9999 and doesn t affect the zero value offset of the gauge The sensitivity of the sensor can be changed by changing the ca
15. cur The following are a few tested greases Elmgren 1995 giving 1 kPa hysteresis between on and offloading curves e Statoil LK 62 e BPLT2 e Ariens moly No I The corrected tip resistance qr and sleeve friction fr are essentially unaffected by the types of filter and fluid used Elmgren Kjell 1995 Slot type pore pressure CPT u filters Behavious of different filling media CPT 95 International Symposium on Cone Penetration Testing Link ping 4 5 10 1995 Vol 2 p 9 12 Larsson Rolf 1995 Use of a thin slot as filter in piezocone tests CPT 95 International Symposium on Cone Penetration Testing Link ping 4 5 10 1995 Vol 2 p 35 40 3 3 9 Pre stressing the friction sleeve 10 cm probes Remove the funnel and tighten the cone firmly but only by hand This will provide a pre stress on the friction sleeve with approximately 5 kPa When later on the probe is pushed into the ground the tip will be tightened harder The tip will not loosen unless the probe is turned anticlockwise in ground When the tip is tighten the filter ring will pressing on the lower X ring close to the point which will then press on the friction sleeve The sleeve in turn is pressing on both the upper X ring towards the sound transmitter and the local friction sensor inside the probe This initial pressure will remove any slip between sleeve and the local friction sensor and is paramount in order to measure small frictions and to a
16. d transmission Mud adapter for microphone First extension rod w mud outlets VIII Data Acquisition and Software CPT LOG Win 95 min Pentium min English version Interpretation program CPT PRO by Geosoft CPT pro Interpr Mod ver 5 31 CPT pro Formula Editor CPT pro Cross section module CPT PRO Data editor Map LT GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 6 27 GEO H TECH The Geotech CPT probes are equipped in their standard version with the following channels e 10cm probes point resistance local friction pore pressure channels and tilt sensor Seismic adapter and electric conductivity adapter are options that can be mounted on Geotech CPT probes The above channels are described in the separate manuals for each adapter Please refer to the given manual All items are described in the Geotech catalogue or on the Geotech web site http www geotech se 1 3 The Geotech cordless CPT System Unless for special applications such as offshore or SCPT most of Geotech clients choose to run CPT using the unique Geotech cordless data transmission system This cordless system applies to all channels except seismic i e point resistance local friction pore pressure tilt temperature and electric conductivity GEOTECH started the development of cordless CPT system in the late seventies and the equipment was made operational in extensive offshore CPT surveys in the Canadian Arctic in the early eighti
17. er to guarantee the sound transmission Geotech can provide a device for those who wish to use a rotary unit and chuck to tighten and loosen rods GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO DTECH seen 3 3 6 Batteries The 10sq cm probe is powered by 4 pieces of alkaline C batteries The lifetime of this power pack is normally around 12 hours The lifetime is shorter if the probe is operating at lower temperatures than the normal soil temperature e g if the probe is operating for long time in the air when it is freezing The voltage should always be checked and for is for fresh batteries 6 Vdc Check prior to all soundings the voltage as the probe stops functioning at a voltage lower than 4 5 Vdc Use only hand power to tighten the cone to the sound transmitter In spite of this it could be necessary to use tools to dismantle the probe after the sounding High point resistance could tighten the probe quite hard 3 3 7 Saturating the pore pressure chamber and mounting point and filter ring Introduce the probe in the funnel or a cut plastic soft drink bottle and water tight with tape Fill with glycerine and place a deaired a point an X ring an X ring suppor and a filter ring Carefully remove all air bubbles in the pore pressure chamber with a syringe or a needle This will take at least 10 minutes if the probe is new Mount the X ring on the support ring and place them on top of the probe then the deaired filter rin
18. es Jefferies M G and Funegard E 1983 Cone penetration testing in the Beaufort Sea Proc ASCE Conf Geotechnical Practice in Offshore Eng Austin Tx The present equipment is a fourth generation and is still today unique on the market The system does not require a cable to transmit measured data from probe to soil surface This is done acoustically i e the digitised coded data string is converted into a high frequency acoustic signal by a piezoelectric element in the probe The signal is then transmitted up through the steel of the rods to a microphone on the rig or penetrometer No cable is therefore used for transmitting the data from probe to the recorder at the surface The absence of a cable makes the system very easy and time efficient to use From the microphone the signals are transmitted to a computer interface box which also receives depth information from a depth encoder The data is then sent to a PC notebook The data are presented simultaneously on the PC screen as curves and digits GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO H TECH 7 27 A 4 GEO TECH A CPT COMPUTERINTERFACE Vv Figure 1 Description of the Geotech cordless CPT system 1 CPT probe 2 Microphone 3 Depth synchroniser or depth encoder 4 Computer interface box 5 PC Notebook 6 Printer 7 Res
19. g and the point S E S fo fl 7 F x gt lt Figure 6 Deairing the pore pressure chamber and mounting the X ring filter ring and point GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO H TECH ane 3 3 8 Use of slot type filters In unsaturated soils and soils where negative pore pressures are generated during penetration conventional filters may loose their saturation and not respond to pressure changes see Fig 7 below While this loss of saturation is permanent when penetrating unsaturated soils it returns to normal in the second case provided the pores of the filter have not been clogged with soil particles For shallow layers the loss of saturation can be avoided by pre drilling and filling the hole with water The alternatives to porous filters are slot type filters with the pore pressure chamber filled with grease The cause of loss of saturation when negative pore pressures are generated is the formation of gas due to the lowering of the evaporation temperature of glycerine and even more of water when the pressure is reduced under the atmospheric pressure With a pressure reduction of 70 80 kPa below atmospheric pressure water or glycerine starts boiling Larsson 1995 This will not occur when filling the pore pressure chamber with grease using a slot type filter unless air bubbles remain trapped in the grease Tip resistance MPa
20. g box It is preferable to keep the signal conditioning box and interface box above sea level The observation of the diodes of the interface box is a good monitoring of the CPT test If not possible the two boxes can be paced in a watertight caisson on the sub sea rig GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009
21. h encoder is replaced by a watertight version with a wheel rotating against the rods Fig 12 The unit consists of e An outer part with the rotating wheel which is loosened regularly for greasing of the bearings e An inner part which should under no circumstances be opened It consists of a two couple of magnets which transmit the rotation of the wheel through the watertight separation the electronic unit with cable connections The inner part does not require any maintenance Mounting of the depth encoder Depth increments are only registered in one rotation direction In order to establish the proper direction of rotation connect the depth encoder and the CPT probe with the interface box and PC start the acquisition program CPT LOG and a simulated CPT test In case no depths are recorded turn the depth encoder upside down in order to change the direction of rotation Once the orientation of the encoder is established mount the unit with a spring load with a load of 4 kg on the rotary wheel against the CPT extension rods GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO DTECH on Measuring wheel rota ting against the CPT rods 2 pair of magnets al NAL A PA sy Fe JET FIA St yu N ZA Bolts to loosen outer Electronic unit ZASS Measuring wheel axis Figure 12 Depth encoder for sub sea use The depth range of the depth encoder is 40 m Interface box and signal conditionin
22. ission from probe Sound transmitter for 36 mm tapered thread rod price per probe Microphone top mounted 20 ton Cable microphone to interface box Data acquisition and software CPT interface box for PC logging with CPT LOG software Cable serial interface box to PC Cable power interface 12V Acquisition and Display Software for PC Windows 95 or better CPT LOG Logging software for PC Transportation case for CPT probe Minimum set of spares Point hardened steel Friction sleeve hardened steel Filter ring brass X ring O ring friction sleeve set of 10 Extension rods Tapered thread rods 36 x 1 000 mm Transport case for extension rods 115 x 23 x 17 cm II CPT Probes Probe 3 channels qc fs u 10 sq cm 50 MPa temp comp tilt Probe 3 channels qc fs u 10 sq cm 50 MPa temp comp tilt memory Probe 3 channels qc fs u 10 sq cm 100 MPa temp comp tilt Probe 3 channels qc fs u 10 sq cm 100 MPa temp comp tilt memory P N 12425 12428 41310 12429 41380 10702 13579 08969 10661 00000 00000 08871 08882 08876 08883 10779 10604 Description III 10 sq cm Probe Spares Point hardened steel Friction sleeve hardened steel Filter ring brass Support ring to X ring X ring O ring friction sleeve set of 10 O ring battery pack IV Back up Memory Extra back up memory module for probe 8 hours capacity Memory read out unit NOVA V Soun
23. k up memory of minimum 36 hours capacity and 18 bits resolution The purpose of this back up memory is to SY Nicer guarantee a data logging in case of losses of data step 2 5 with the cordless data transmission due to high Press Next button to start dumping using cone conected on COM11 ambient noise levels when penetrating dense sands acoustic interferences on the pusher or Select dump range due to too large penetration depths Failures in Read all memory l the data transmission can be observed as straight oa ome lines on all channels in the recorded profiles IV Save dump in specified file C Users GEOTECH Desktop dump dr txt Bl Erase PITTI T TITTLE lt Back Cancel 4 1 CPT soundings with cones with a back up memory They differ only slightly from the procedure with a standard cone Only the differences are therefore described here 1 After starting the CPT acquisition software CPT LOG make certain that the cone is defined as a Back up type in the Cone Database module 2 Connect the memory read out cable in the probe and lap top 3 Start the Penetration module press Fl New Sounding 4 Go to Options gt Cone synchronization and wait for the synchronization to finish 5 Continue the sounding as normal This procedure is not necessary to be done before each test unless lap top is exchanged but it is recommended to be done first test of the day Once
24. libration code If the calibration code is increased the sensitivity of the sensor will be decreased lower gain To check that the measured value from the CPT probe is correct the CPT probe should be loaded in a loading frame and the read out from the CPT probe should be compared with the read out from an accrue load cell If the value differs a new calibration code can be determined from the following formula Cn Co Pr P1 Where Co is the old calibration code Cn is the new calibration code Pr is the read out value from the CPT probe Pl is the loaded value on the load cell The relation between the read out value from the CPT probe and the load cell is not a linear function for the pore pressure and the friction sleeve sensors Therefore the calibration code is only valid for a certain load When determine a new calibration code the corresponding load on the CPT probe should be in the area where the highest accuracy is needed Sometimes it can be necessary to use different calibration codes for different soundings depending on soil conditions When loading the sensors of the CPT probe it is important to point out following details e The probe should be loaded with friction sleeve filter ring and cone tip and all X and O rings mounted on the probe The probe and its parts should be well cleaned and all sealing lubricated with Vaseline The cone tip should be tightened by hand and the friction sleeve turned half a turn to centre
25. or different types of soils If the soil surface consists of clay or mainly clay anchoring augers with large diameters are preferable Suitable diameters are between 100 mm and 200 mm If the soil surface consists of non cohesive soils augers with a smaller diameter are sufficient but may have be driven down to a layer with sufficient reaction force If the torque needed to drive the augers is very high it could help to lubricate the augers e g with bentonite 3 3 4 Depth Synchronisation Unit DSU The Depth Synchronisation Unit comes as a spring loaded string pot or as a wheel rolling on the rods For the spring loaded string pot weld or screw the mounting plate in a suitable position on your pushing unit and arrange for a hook e g screw The Depth Synchronisation Unit and the hook should be mounted n a moving respectively fixed item or inversely Make however sure that the wire runs in a straight and vertical line all the way to ensure correct depth registration It is preferable to protect the wire from grease dirt and water The rolling wheel model has a wheel rotating against the extension rods The unit is mounted so that a firm and constant contact between rods and wheel is ensured 3 3 5 Microphone The contact surface at the end of the rod string where the pushing action is transmitted is the microphone The microphone should therefore be mounted under the pushing It is essential that good mechanical contact is achieved in ord
26. ructions in the manual and on the screen displays Check the zeroes by holding the probe by hand against the microphone The probe should not be subject to any load Do not therefore e Let the probe rest on the ground loading the point e Introduce the probe in water loading the pore pressure sensor e Hold the probe by the sleeve friction It is important that the zeros are read with the probe holding a temperature close to the soil temperature as the temperature drift is largest source of measurement error Non linearity for the point resistance lt 0 1 FS with temperature stability lt 0 05 FS 10 C It is recommended that the probe and transmitter have been connected at least a minute before zero readings is made More background information is found at the end of the manual 3 3 12 CPT SOUNDING Start the CPT sounding At the end of each stroke pull the yoke or drill head back up and add a new rod without going into PAUSE mode Both CPT LOG and CPTGL can monitor dissipation tests At the end of a sounding never stop the logging software All soundings must be terminated with a second zero reading once the probe is retrieved from the ground This is to check any sensor drift The data cannot be displayed with the software without zero checks before and after testing GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO TECH men 4 USE OF CONES WITH A BACK UP MEMORY The Geotech CPTU probes can be equipped with a bac
27. t Cables Overload control card 6 3 1 Mounting Instructions 6 3 2 Use of the overload control card with the CPT logging software 7 1 17 2 1 3 Calibration codes Sensors and sealing Zero readings 8 SPECIAL APPLICATIONS 8 1 8 2 8 3 8 4 CPT Soundings with cable mode data transmission Mud lubrication to reduce skin friction along the extension rods CPT Tests in very soft grounds Offshore CPT GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 3 27 17 17 18 18 18 19 19 19 20 20 20 21 22 23 23 23 24 24 25 GEO H TECH 4 27 1 THE GEOTECH CPT EQUIPMENT 1 1 Probes and Equipment available The Geotech CPT equipment consists of the following main items Rigs or penetrometers Geotech Probes Available channels Area factors see calibration report Data Transmission Power supply Extra features Data Logging Data Interpretation e Multipurpose Penetrometer with 20 ton push force model 220 e Continuous Penetrometer 20 ton e Multipurpose Site Investigation Rigs with 4 to 7 ton push force models 504D 604D 605D 607D 707D e 10 sq cm with 20 50 or 100 MPa Point resistance Qc range Most probes come with three Qc fs u or four channels tilt in addition e Point resistance Qc 20 50 or 100 MPa range Overload capacity 25 e Local friction fs 0 5 or 1 MPa range Overload capacity 50 e Pore pressure u 2 MPa range Overload capacity
28. ters or if you want to use already used tips it can be done in the field This is not a recommendable method but it works tolerably Put a deairing funnel over the cone and fill it with water Mount and dismount the tip at least 20 times Refill with water all the time Have washing up liquid added 3 2 2 Pre augering In order to obtain good quality pore pressure measurements pre drilling must be carried out all the way down to the ground water table If the first meters consist of dry crust with clay or silt pre augering down to 0 5 1 0 m could be enough If the first meters consist of fillings pre augering is recommendable through the whole filling If the soil seems to collapse into the hole it must be stabilised with a casing or e g bentonite If a casing is installed it must than be filled up with water During winter time when ground frost is present pre augering must always be carried out If the probe is pressed through soil frost there will be an under pressure which can suck the water out of the filter This will cause a generated pore pressure curve that is very inaccurate GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO DTECH vee 3 3 3 Anchoring The pushing unit e g penetrometer or site investigation rig has to anchored to the ground if its weight is lower than the available feeding force and lower than the expected reaction force it could be advisable to anchor the unit Different augers are used f
29. the memory is filled it will overwright the first sounding and continue in a loop By request it is possible to set an overwright protection on the back up memory GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH Data retrieval At the end of the test or of the day you can if necessary transfer the data saved in the back up memory to your lap top 1 Connect the memory read out cable to your probe and lap top and start the Back up Memory module of the CPT LOG software 3 Follow the instructions in the Memory window that shows Since no depth and time is recorded in the back up memory the file needs to be synchronized with the original file saved on your lap top The new CPT files are labelled as the original ones but with a _m cpt More information in the CPT log manual The memory is emptied when all data are transferred or when Erase is pressed All data are always stored in a dump txt file 5 AFTER THE CPT SOUNDING 5 1 Cleaning the probe After sounding it is very important to clean the probe Dismount the point and filter ring from the cone and put them in a tank with water so they don t get dry Dry soil is very hard to get rid of from inside the filter Dismount the friction sleeve by careful rotation and pull it off Clean the O rings and the X rings both under the sleeve and on the cone Wipe the moisture away If it is wet under the friction sleeve water has penetrated
30. ults 1 4 Technical data CPT probe See special documentation Sound Transmitter or Cable See special documentation Microphone Weight 3 5 kg Mud adapter 0 5 kg Computer Interface Dimension 170x210x55 mm Weight 1 2 kg Power 9 36 Vdc Connection RS 232C 600 2400 Baud Depth Synchronising Unit Electrical optical Dimension 160x160 mm GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 Software requirement CPT LOG Win PC notebook with minimum 486 processor 8 MB RAM Windows XP Vista GEOQTECH 2 1 8 27 EQUIPMENT NEEDED Checklist PC Notebook IBM or IBM compatible Pentium minimum for CPT LOG 286 processor for CPTGL Notebook excluded in sale Geotech CPT Interface box for PC logging Cable power interface 12 Vdc Cable serial interface box to PC Depth synchronisation unit also called Depth encoder Cable depth synchronisation to interface box Microphone with mounting plate Cable microphone to interface box CPT U Probe 10 sq cm with Sound Transmitter Batteries 4 pcs alkaline C Calibration certificate for the probe and user manual Can with deaired points and deaired filter rings Bring at least as many filter rings as the planned number of sounding during the day Container and funnel with glycerine If a funnel with a 10 sq cm bottom opening is not available cut bottom and top at approx 10 sq cm or 36 mm diameter of a large soft drink plastic bottle Drill rods gener
31. under the O rings They are damaged and must be replaced Lubricate the X rings and the O rings slightly with Vaseline and mount the friction sleeve The sleeve is now easily turned If the X rings and O rings are not clean this may affect the local friction readings When the probe is pulled back from the ground soil could penetrate above the upper X ring which will force the friction sleeve downwards During the next sounding the friction from the soil must first press the soil out from the X ring before the measuring is started GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEO H TECH 6 INSTALLATION DESCRIPTION 6 1 Depth Synchroni sation Unit 19 27 The DSU is initially made to give increasing depth when the wire is going inwards If you desire the reverse e g increasing depth when the wire is pulled out you swap the wires on pin B and pin C in the cable connector that is connected to the interface The DSU should be mounted so that the wire runs downwards to avoid water entering the box Depth sync cable INTERFACE DSU A ONC N C OA Bc green yellow OB black1 Oc D ON C N C OD EO black 2 OE F o black 3 SF Microphone cable MIC A O NC N C OA B O N C Nc OB C O N C N C OC A Blue er DOC COD EO Brown OE F O NC N C OF Serial cable 9 pin D sub 25 pin D sub Ac 3 2 BO 2 3 CONG DC 5 7 Power cable ie BATTERY Bo co p o blue GND g eo O 1245V DC Fo Figure
32. void non linearity at small loads This initial pressure on the local friction and cone resistance sensors is static and will not change during the penetration of the soil unless the sealing leaks Finally this pressure is tarred when the zero values of the sensors are read before the start of the test and it will therefore not affect the readings It is important that there is an initial load of approx 5kPa on the local friction sensor before the zero reading of the sensor If not the friction sleeve may not be in contact with the sensor resulting in a gape which will give the friction reading GEOTECH AB NOVA CPT Acoustic manual 2009 doc 2009 GEOWDTECH nee 3 3 10 Other Channels Tilt Temperature and Electric Conductivity The tilt channel does not require any special care nor is it recalibrated It is mounted in the electronic part of the probe above the friction sleeve approximately 7 cm from the upper end of the probe The temperature sensor independent from the sensor for temperature correction in the probe of all CPT measurements is mounted in the electronic part of the probe as well 2 5 cm above the friction sleeve Temperatures are recorded in degrees centigrade The sensor is recalibrated together with the other CPT sensors For the seismic adapter please refer to the given manual 3 3 11 Zero Readings Start the computer and input the probe characteristics calibration values and start a CPT test by following the inst
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