CPT is a valuable tool for engineers working on roadway projects because it offers unmatched efficiency and accuracy for collecting in-situ data. Roadway engineers rely on CPT data to inform design of pavements and foundations for roadway structures like signs, safety railings, bridge piles and aprons, subgrade materials, and pavement. This post will provide an overview of how CPT is used to assess the sediment beneath roadway structures and improve the longevity of roadway infrastructure.
CPT involves statically advancing a sensored probe with a conical tip up to hundreds of feet below the ground subsurface to collect in-situ readings of three main measurements: tip resistance, sleeve friction, and pore pressure. These measurements can then be used to determine the sediment strength and the structure’s stability by calculating several values which can generate a soil behavior type and several other correlations. This information is vital for designing subgrades and foundations that will support the loads from large vehicles and structures.
How CPT is Used with Roadway Structures
CPT can be used with other methods like standard penetration testing, and offers the ability to conduct P-wave and S-wave seismic tests. According to ASTM D7400/D7400M-19:
“Accurate in-situ P-wave and S-wave velocity profiles are essential in geotechnical foundation designs. These parameters are used in both analyses of soil behavior under both static and dynamic loads where the elastic constants are input variables into the models defining the different states of deformations such as elastic, elasto-plastic, and failure. Another important use of estimated shear wave velocities in geotechnical design is in the liquefaction assessment of soils.”
The data provided by CPT software is used by engineers to assess subsurface conditions and help inform foundation design. With Vertek’s CPT software, you can instantly share the data you collect via email. CPT is a valuable tool for engineers working on roadway projects because it can provide information about the soil that may be unavailable from other methods. In addition, it is safer, more efficient, and less disruptive to the earth.