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Highways Site Investigation

The CPT (cone penetration test) is a fast and economical means of conducting highway site investigations. It is suitable for exploring soils and soft ground for the support of embankments, retaining walls, pavement subgrades and bridge foundations. 
   
   
 Click here to download our capability statement 2.81MB    
 
   
Multiple and simultaneous readings
 
The ability of the CPT to collect multiple and simultaneous readings, with depth, is a valuable asset. Special cones can be run concurrently with the standard cone test to evaluate the natural foundation  material properties which include :

  • shear wave velocity
  • in-situ water content
  • porewater pressure,
  • shear modulus 
  • shear strength

   
Environmental cones

   
In addition, a number of environmental probes are available to measure:

  • total gamma radiation
  • pH
  • conductivity
  • resisitivity
  • temperature
  • hydrocarbon detection
 
Sampling
   
There are a number of myths relating to the CPT.  Perhaps the biggest myth is that it cannot obtain sample. This is not true, the CPT platform can be used to deploy:
  • high quality Bergemann (Delft) piston samples in soft clays >>
  • fixed piston MOSTAP stockinet samples >> 
  • thin wall Shelby samples >> 
  • “disturbed” push windowless samples

 
Soil parameter evaluations
   
The highway engineer, perhaps more than most, requires a wide range of geotechnical parameters to assist in the design of  suitable fill materials, cutting and embankment slopes, foundations and their deformation under structural loadings, and pavements.
   
Within the UK, the CPT is an under-identified tool for the rapid assessment of geotechnical parameters.
   
It should be noted that no uniform and consistent methodology currently exists to interpret all necessary soil engineering parameters within a common framework, however, the CPT platform can be used to deploy specialist modules to determine ‘analytical’ geotechnical parameters.
   
Such modules, include push pressuremeters; seismic cones; in-situ water content determination probes; shear strength vane apparatus and many more.
   
The use of these modules reduces spend on expensive laboratory tests and provides data in real time - unlike the days or weeks for laboratory test results to be determined
   
   
CPT correlations
  
Click here to see a selection of CPT correlations that can be expected to apply to consistent soil types of common minerologies such as Kaolin, quartz, feldspar and those of common geological origin (marine and alluvial).
   
Many more correlations exist.
  
 
Instrumentation
 

Lankelma has a modified CPT platform to install a variety of geotechnical and geo-environmental instruments that include:

  • Conventional standpipes and standpipe piezometers
  • Gas monitoring and small diameter water wells
  • Multi-level levels
  • Vibrating wire and BAT piezometer systems
     





 

Highways Site Investigation



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