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DMPe Borehole Dilatometer



The DMPe Borehole – or Flexible – Dilatometer equipment is designed for the in situ determination of the deformation modulus of rock masses in 96 mm or 101 mm boreholes


The DMPe Dilatometer consists of a probe with a metal central body. The probe includes:


  • An inflatable membrane (rubber sleeve) equipped with three pairs of metallic inserts spaced at 120° intervals
  • A split spring-ring and double cone membrane retaining system
  • Three pairs of inductive displacement sensors with two measurement points each.
  • A pressure sensor allowing to measure pressure in the probe
  • A sediment collector


The probe is read with the D/P BOX Readout which is operated with an Android tablet (see datasheet D/P BOX for more details). A dedicated application, allows configuring the tests and calibrations, displaying and plotting the test results in real-time, logging the data.


The dilatometer probe is designed to be lowered down into the borehole using a string of rods. Nitrogen compressed dry gas is used for pressurizing the probe.


The borehole dilatometer test consists in loading the rock in progressive pressure steps and measuring the diametrical deformation resulting from this loading.


The test is used for generating the following parameters:

  • A modulus of global deformation
  • Elastic modulus measured on cyclic loadings
  • Creep parameters
  • Anisotropy of the rock mass
DMPe Probe
Weight45 kg
Diameter90 mm (96-mm borehole)

95 mm (101-mm borehole)

Probe / Membrane  Length1.8 m / 1 m
‘HR’ Membrane (standard)For soft to hard rock
3 Inductives Displacement Sensors
Calibrated Range20 mm
Resolution (D/P BOX)1  μm
Pressure Sensor
Max Working Presssure20 000 kPa
Resolution (D/P BOX)1 0  kPa
D/P BOX Readout
User InterfaceBluetooth communication with an Android tablet
Power Supply2 x 12 V, 2.3 A, rechargeable batteries
Data Output FormatCSV, spreadsheet compatible
Dimensions25 x 28 x 12 cm (l x w x h)
HousingSplashproof, resistant ABS case
Autonomy> 8 hours typically
Power supply interfaceUniversal AC wall plug with US/Euro adapter + adapter cable for car (lighter) & for external battery
Ordering Info

Please Specify:

  • DMPe design, 90 or 95
  • Tubing & Cable Length (Special configuration required over 150 m)
  • Accessories


  • Flexible High Pressure Pneumatic Tubing with Connector
  • Electrical Cable
  • CRAELIUS 50 & 60 Type Connectors
  • Cable Reel
  • Pressure Regulator, Manometers & Valves
  • DP Box Readout Unit
  • Spare Membrane 90 or 95

Optional Accessories

  • Spare Set of Displacement Sensors
  • Tools Kit for Assembling and Disassembling the Membrane
  • Carrying Box for the Dilatometer Probe
  • Kit to transform DMPe 90 into DMPe 95
  • Kit to transform DMPe 95 into DMPe 90
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