University of Portsmouth

Key laboratory expertise

  • Volcano-tectonics and seismology
  • Physical properties of rocks and minerals
  • Rock-fluid coupling and permeability
  • Hydraulic fracturing
  • Earthquake mechanics
  • Rock physics and Geophysics
  • Applied rock mechanics and rock engineering
  • Engineering geology and geotechnics

 

Staff and Students

The work of the group is supported by 5 members of full time academic/technical staff:
Dr. Philip Benson
Emily Dunkason
Dr. Nick Koor
Dr. Carmen Solana
Dr. Gareth Swift

We currently host 3 PhD students directly, with an additional 2 researchers supported in other EU institutions as part of international collaborations:
Mr. Ricardo Pedreiras-Tomas
Mr. Peter Ibemesi
Mr. Smart Osarenogowu
Dr. Thomas King (Turin)
Mr. Thomas Alcock (Turin)

The laboratory typically support a further 6-8 MRes and/or MSc projects annually on a range of project topics.

Alumni from the lab can be found in academia, industry, and government posts worldwide.

Rock Mechanics Laboratory

The research of the group focuses on how rocks deform, under what conditions of pressure and temperature, and how the physics of the process generate signals such as seismicity that be used to better understand our natural world. Earthquakes, whether small or large, are a ubiquitous method for monitoring rock deformational processes across a wide scale, from deep megathrust earthquakes such as the great Tohuku earthquake of 2011 (Japan), to volcano-tectonic earthquakes that commonly precede eruptions, to small, localised, tremors associated with mining, fluid injection, and geothermal activity. By understanding the physics behind these processes, the research of the Rock Mechanics Laboratory seeks to better link seismic and elastic wave velocity data to the pressure conditions and failure characteristics of the rock mass. To achieve this, we use the latest technology in high pressure rock deformation machines, equipped with systems for controlling stress, strain, temperature and fluid flow, and instrumented with advanced Acoustic Emission recording technology – the laboratory analogue of a natural earthquake. Although our key focus is on fundamental rock deformation and tectonophyics, the laboratory also has a rich history (50+ years) in the applied geosciences, supporting teaching and research on a wide variety of engineering geology and geotechnics topics.

Equipment

Instron 60 tonne uniaxial press: The workhorse of the laboratory is a 600 kN uniaxial loading frame equipped with ancillary pressure systems to provide confining pressure via a simple Hoek-type cell. Force and strain are digitally logged, and a 2 channel Physical Acoustics PCI-2 AE setup allows fracturing to be measured.
Controls shear box: Digitally logged hydraulic shear box for the testing of rock samples up to 115 x 125 mm.
400 MPa Large Bore “Harwood” Hydrostatic pressure vessel: This hydrostatic pressure vessel is one of three rock physics vessels that were acquired from the university of Wyoming where they were previously installed and used as the laboratory of David Fountain. The largest of these can accommodate a large sample of 100mm diameter and 250mm long up to pressures of 400 MPa (approximately 16 km). The sample assembly is equipped with P-wave and S-wave transducers for measuring elastic wave velocity and is plumbed for the application of pore fluid/pressure.
600 MPa / 400C “Autoclave” Hydrostatic pressure vessel: Our mid-size hydrostatic pressure vessel is fitted with an external clamshell furnace that that heat the pressure vessel (and sample) to 400°C for measuring P-wave/S-wave velocities and AE at pressures of up to 600 MPa, approximately 24 km. This cell is used for measuring P/S ratios under conditions similar to shallow subduction and volcano-tectonics. 
100 MPa Triaxial “rock physics” cell: This new triaxial cell is the latest addition to the laboratory, and is equipped with the latest instrumentation for dynamic permeability and elastic wave velocity measurements up to 4km simulated depths and 200°C. The maximum stress (across a 40 mm diameter) of 700 MPa allows the deformation of most rock types in the shallow crust for basic research into earthquake and rock physics. Most recently we have developed a novel sample assembly to simulate hydraulic fracturing processes in the (controlled) laboratory environment.

ITASCA-Image “Milne” and “Richter” advanced Acoustic Emission system: This state-of-the art Acoustic Emission recorder (Applied Seismology Consultants) can measure 12 channels of AE data simultaneously, and locate the locations of the earthquakes in quasi-real time for display and analysis at data rate of up to 100 events/second. The instrument can also be used in a active mode, ‘pinging’ successive sensors to generate a dense P-wave raypath network for tomography. The recorder is used during triaxial deformation experiments to investigate the fracturing and cracking processes, due to applied stress and pore pressure, and with reference to fluid resonances.
High speed camera system: To investigate high speed fracture and other dynamic processes we use a HotShot 1280cc high speed camera capable of shooting 1000 frames per second into a 30 second high speed memory.

Helium pycnometer: Micrometrics AccuPycII 1340 is a helium displacement pycnometer for the high accuracy measurement of skeletal and apparent volume and density. It is used for measuring porosity of powders and solid rock samples.
Carbolite Furnace: Capable of 1200C and with a sealed tube this furnace may be used for thermally treating rock specimens to induce fracture (with AE recording) and/or monitoring gas emission.

Current Projects

- A new laboratory method for measuring hydraulic fracture permeability at reservoir conditions;
- Low-frequency volcanic events events generated by poorly consolidated volcanic rocks: implication for volcano hazard and flank collapse;
- Mapping rock friction and coupled fluid mechanics in active tectonic systems using high and low speed stick slip simulations on gypsum;
- Integrating multiscale tomography techniques for determining the physical properties of the volcano tectonic systems, from laboratory experiments to field scale ;
- Linking fracture and permeability evolution to geothermal reservoir parameters in engineered Hot Dry Rock systems;
- Flank collapse controls on Stomboli volcano: new insights from combined rock physics and remote sensing;
- Fluid viscosity and temperatire effects on tensile driven fracture;