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GOST – System (Geotechnical Offshore Seabad Tool)

GOST is an innovative geotechnical tool to characterize the subsoil by means of ‘push-in tools’, i.e. cone penetration testing along with pore pressure measurements, known was CPTu.
The primary focus of GOST is offshore site investigation but due to its modular layout, the system also works onshore, for instance mounted on a truck.
GOST is mainly designed to operate from the seafloor. It is powered and controlled via a standard single wire coaxial cable. During continuous offshore surveys, the tool is only slightly lifted from the seafloor and hanging within the water column during site-transit – called “dangling operation”. GOST stays under water without the need of full recovery until all sites are penetrated. This leads to a large number of tests in considerable less valuable vessel time than any other top-pressed CPT tool would be capable of.
GOST can handle rod setups of many diameters. So far, we use a ‘digital subtraction cone’ of 5 cm2 in conjunction with a differential pore pressure system on a rod of 2 cm in diameter.

Components

  • load frame
  • weight setup
  • hydraulic power unit
  • hydraulic feed motion (push/pull)
  • hydraulic rod clamp
  • valve block
  • telemetry (energy & data)
  • underwater transformer unit
  • underwater controll unit
  • CPT cone
  • penetration measruement
  • inclinometer
  • absolute pressure measurement
  • coiled rod (optional)
  • hydraulic leveling (optional)

Characteristics

  • operation on-& offshore (4000 m depth of water)
  • up to now penetration 38 m
  • push power up to know 8000 kg
  • high- resolution of all data
  • short mobilisation time
  • own winches
  • low operation volume (1x20" Container)
  • additional sensors are possible
  • CPTU data DIN 4094 compatible
  • diverse in-situ soil tests possible
  • live monitoring
  • continuous push with different speed
  • VIBRO-Mode - feet motion with overlain frequency

Measuring Parameter

Standard

  • tip resistance
  • sleeve friction
  • differential pore pressure
  • inclination ( X & Y - axis)
  • acceleration (Z - axis)

Optional

  • heat conductivity
  • magnetic susceptibility
  • activ gamma probe
  • passiv gamma probe
  • seismics probe
  • electrical conductivity
  • magnetometer
  • gas & water probes

Technical Details

CPT Sonde

  • tip cross section of 5 cm²
  • A cone body of hardened stainless steel1.4112
  • max. resolution of 30 N or 0.06 MPa
  • max. range of 60 kN or 120 MPa
  • sleeve friction mode in subtraction-mode
  • force detection with two linear DMS load cell
  • A/D Converter with 24bit resolution – 250Hz sampling
  • processing with averaging about 10 values
  • industry digital interface (RS485 BUS), 28Hz Data rate

Differential & Absolut Pore pressure

  • sensor location directly within the tip
  • first port at the tip, u2 position
  • second port at the rod end as reference
  • range +/- 14bar
  • resolution digital of 0.01 bar

Inclination Sensors

  • Spatial Directions of X & Y-Axes
  • Range of ± 35° Inclin. Angle
  • Resolution Digital of 0.1°
  • Acceleration on the Z-Axis

Interface

  • Digital Interface about industrial RS485 BUS
  • overvoltage and reverse protection
  • direct A/D converting of measured variable
  • no scallingt with amplifieres
  • 250Hz sampling
  • Averaging inside the probe
  • Datarate of 38Hz

Hydraulic

  • 8.000kg hydraulic push power
  • infinitely variable hydraulic pressure 0 – 200bar
  • pressure compensation hydraulic system
  • Powerful MOOG servovalve
  • continued feed motion
  • VIBRO-Mode – frequency overlay feed motion
  • hydraulic leveling (optional)

Telemetry

  • data comunication with long range modem
  • max range 10 km and data rate 330 kbit/s
  • max. 3500 W Electrical power at the seafloor unit
  • 1500 V at the coaxial cable

Lifting appliance

  • three point suspension
  • high turning protection
  • mobil 10000 kg winch
  • mobil 1500 kg Tension winch
  • load bolt inside the bloc
  • electronic regulator for tension winch
  • mobile hydraulic power unit

Truck

  • off-road 6x6 drive
  • full winch assembly
  • mobile A-Frame
  • cross beam with bloc
  • 10000 t winch
  • 1500 kg tension winch (elektronic regulated)
  • fully configurated lifting appliance
  • short mobilization time
  • on board hydraulic power
offshore

Application

  • cable lines exploration
  • foundation on & offshore
  • sewer conduit construction
  • pipeline construction
  • foundation exploration on & offshore
  • groundwater exploration
  • environmental monitoring and measuring technologies
with additional sensors, we can expand for any cases
Fino2

Data sample

Datenbeispiel

Details on GOST - Operations

 

Operation/usage:
Scientific projects: MARUM/University Bremen, working group Marine Engineering Geology
Commercial projects: Uni Bremen Campus GmbH and Geo-Engineering.org GmbH

Property of:
Device: University Bremen, periphery: Geo-Engineering.org GmbH