1. Field characterization of problematic earthfills, by DMT. A case history Nuno Cruz - MOTA-ENGIL; Universidade de Aveiro, Portugal Isabel Caspurro - Estradas de Portugal, Portugal Sofia Guimarães & Cristina Cunha Gomes - COBA, Portugal António Viana da Fonseca - Universidade do Porto, Portugal

2. General Conditions  Some weeks after its opening - signs of movement around the hydraulic cross, settlements on the platform and sidewalks and tension cracks along the slopes, showing a general instability of the earthfill  Earthfill of 150m long with 6,0m and 4,5m high on the right and left sides  Cross a water line, where a hydraulic cross ensures its drainage  Located in ring surrounding Oliveira do Bairro at the Centre- North of Portugal

3. Mechanical Caracterization 0,0 – 3,0m – Very loose (qd < 2MPa)0,0 – 3,0m – Very loose (qd < 2MPa) 3,0 – 5,5 – Loose (2 – 4MPa)3,0 – 5,5 – Loose (2 – 4MPa) 5,5 – 6,0 (foundation) – Loose to very loose (1 – 3MPa)5,5 – 6,0 (foundation) – Loose to very loose (1 – 3MPa) > 6,0 – Medium compact (> 7,5 MPa)> 6,0 – Medium compact (> 7,5 MPa)  8 DPL (homogeneity quick testing )

4. Mechanical Caracterization  5 DMT Table 1 – Results of DMT tests * - Earthfill; ** - Foundation DMT Depth (m) Type of soil IDID  (kN/m 3 ) M (MPa) 1 1.0-4.2 4.2-5.5 >5.5 Silt-Silty sand* Silt sand-Sand** 0.5-1.8 2.0-5.0 16-18 17-19 19-20 10-15 5-15 80-110 2 1.0-3.0 3.0-4.5 4.5-5.2 >5.2 Silt-Silty sand* Silty sand* Sand* Silt sand-Sand** 0.5-2.0 2.0-5.0 7.0-8.0 2.0-8.0 16-18 18-20 18-19 5-10 20-60 10-30 3 0.0-3.5 3.5-4.5 > 4.5 Silt sand-Sand** Sand** Sand** 2.0-6.0 3.5-6.5 4.0-7.0 17-19 17 19-20 15-40 18-22 60-200 5 1.0-3.0 3.0-4.5 >4.5 Silty sand* Silt-Silty sand* Silt-silt sand** 1.5-2.5 0.7-2.0 1.5-2.0 19 16-17 18-19 60-80 10-25 30-40 6 0.0-3.5 >3.5 Silty sand-Sand** Sand** 1.5-6.5 3.0-6.0 17-19 17-20 20-40 20-200

5. Background (Cruz et al. 2006) Table 1 – Results of DMT tests * - Earthfill; ** - Foundation

6. Table 1 – Results of DMT tests * - Earthfill; ** - Foundation Background (Cruz et al. 2006) Moduli

7. Table 1 – Results of DMT tests * - Earthfill; ** - Foundation Density

8. RESULTS ID – Material Index Table 1 – Results of DMT tests * - Earthfill; ** - Foundation SOME IMPORTANT TRENDS (Cruz et al., 2006): a) ID > 4 Poorly graded sandy soils b) ID=[1.8 - 4.0] Adequate soils (SM-SC), c) ID=[1.0 - 1.8] Soils with fine content higher than 20% and low plasticity d) ID < 1.0 Soils with high fine content and plasticity

9. Table 1 – Results of DMT tests * - Earthfill; ** - Foundation SOME IMPORTANT TRENDS (Cruz et al., 2006): a) Unit weight (+ 1 kN/m3) has no sensitivity to be used as a quantitative control parameter b) Can be used qualitatively to check other parameters, by its order of magnitude c) In the present situation results are within 16 and 18 kN/m3, much lower than the usually accepted for this type of works RESULTS Unit Weight

10. RESULTS Constrained Modulus Table 1 – Results of DMT tests * - Earthfill; ** - Foundation SOME IMPORTANT TRENDS (Briaud & Miran, 1992; Marchetti, 2001; Cruz et al., 2006) a)Good adaptability of M as a design modulus, since pavement engineering rely on a sub-grade deformability modulus b)Higher execution rates, comparing to the most common testing procedures (ex. plate load tests) c)Much higher sensitivity when using M and OCR than with ED and KD. d)Typically M profiles show a peak value below the top of the layer. The distance between peaks give indication of compaction thickness

11. RESULTS Table 1 – Results of DMT tests * - Earthfill; ** - Foundation Globally CBR < 5% Upper level DMT 5 – 10 < CBR < 15%

12. Stability Analysis Table 1 – Results of DMT tests * - Earthfill; ** - Foundation

13. SOLUTIONS  Rockfill cover of, at least, 3.5m width over the main slope  Indented interface of the rockfill with the main earthfill  Rockfill embedment of 1.5m into the foundation ground  Soil substitution of the first layer in one meter, by more adequate soils, followed by compaction in 0,30cm layers with tight control.

14. SOLUTIONS Table 1 – Results of DMT tests * - Earthfill; ** - Foundation

15. CONCLUSIONS  Very useful for “post-execution” control  Good alternative to control selected earthfill materials and respective mechanical behaviour  Qualitative control of compaction levels by deriving unit weight values through depth;  Definition of a rigidity modulus of the earthfill (layer by layer), very important for design considerations  Control of thickness of compaction layers

16. Thank you for your attention. I hope to have been useful