In situ testing

Plate Load Test in Rock

The aim of the test is the determination of the deformability characteristics of the rock (rock mass).

According to Client’s requirements, tests can be performed in different conditions:

  • on the surface (excavations, trenches) where generally the single-plate configuration is applied and the contrast is realized by means of an anchored loading beam or by a beam contrastrasted by a wall;
  • underground (tunnels, side niches, shafts) where generally the double-plate configuration (two loading areas with diametrically opposite plates) is used.

If site conditions allow it, the double-plate configuration is more convenient compared to the single-plate one. First of all, no external contrasting structures are needed; then the result is the same as if two single-plate tests would be performed at the same time: in effect the two loading areas, both instrumented, allow two independent tests, performed at the same time and with the same loading paths.  

Our know-how, our effective and versatile equipment, experimental/interpretation procedures make the test suitable for a large variety of situations:

  • option of using a single or a double plate;
  • load plate diameter: 0.5-1.0 m;
  • supeficial measurement of the displacements (around the loading area) by means of LVDT transducers with the simultaneous measurement of the displacements at different depth by means of a 6 bases borehole extensometer;
  • depth of the measurement bases: from 0.25 m up to 6.0 m;
  • in the case of double-plate configuration: distance between opposite loading areas from 1.50 m up to more than 4.0 m; 
  • loading pressure exceeding 12 MPa (120 bar);

According to Client’s needs, we can perform fast tests (duration of a few hour base order of magnitude, tipically 5-10 hours) or long duration tests (for the study of the viscous-elastic characteristics of the rock with tests lasting up to many days).

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