EVALUATION OF ROCKFILL PROPERTIES BASED ON INDEX TESTS. A. Veiga Pinto (Mecasolos) M. Quinta Ferreira (University of Coimbra)

Transcription

1 EVALUATION OF ROCKFILL PROPERTIES BASED ON INDEX TESTS A. Veiga Pinto (Mecasolos) M. Quinta Ferreira (University of Coimbra)

2 Click to add title Lisbon

3 STRUCTURAL BEHAVIOUR OF ROCKFILL DAMS STATE OF STRESS STATE OF COMPACTNESS STRENGTH OF ROCH FRAGMENTS GRAIN SIZE CURVE

4 Click to add title MECHANICAL PROPERTIES OF ROCKFILLS CONTINUOUS MODEL MATERIAL LARGE EQUIPMENT

5 INDEX-PROPERTIES Click to add title DISCRETE MODEL >The strength of rockfill blocks to crushing is one of the main factors that influence stressstrain behaviour of this particulate medium. >The physical-mechanical characteristics of rockfill fragments are usually designated as index- -properties. >Those properties, which are determined in tests in a rather expedite and inexpensive way, have made it possible to estimate the mechanical characteristics of rockfill materials.

6 Click to add title INDEX-PROPERTY TESTS CHARACTERISATION OF PARAMETER SYMBOL Texture Compression strength Durability Water sensitivity Porosity Bulk density Uniaxial compressive strength Point load test n γ dg σ c PLS Crushing strength P a 50 Los Angeles LA Slake durability test Id 2 Swelling strain - Non-soluble residue -

7 INDEX-PROPERTY EQUIPMENT TESTS Click to add title Slake durability test Crushing strength Point load test

8 CHARACTERISATION Click to add OF title ROCKFILL MATERIALS Rockfill embankments Dams, roadways, embankments to extend airports. > Type of rock Granite (North of Portugal). Limestone (Centre and Algarve). Schist-greywacke (South). Basalts in Azores and Madeira Islands. > Influence of lithology of rock fragments on mechanical properties of rockfills

9 INDEX-PROPERTIES Click to OF add CARBONATE title ROCKS PARAMETER CLASS 1 CLASS 2 CLASS 3 n (%) γ dg (kn/m 3 ) σ c (MPa) PLS (MPa) P a 50 (kn) LA (%) Id 2 (%) Swelling strain ( l/l.10-4 ) Non-soluble residue (%)

10 Click to add title INDEX-PROPERTIES OF GREYWACKE ROCKS PARAMETER CLASS 1 CLASS 2 CLASS 3 n (%) γ dg (kn/m 3 ) σ c (MPa) PLS (MPa) P a 50 (kn) LA (%) Id 2 (%) Swelling strain ( l/l.10-4 )

11 Click to add title INDEX-PROPERTIES OF GRANITIC ROCKS PARAMETER CLASS 1 CLASS 2 CLASS 3 n (%) γ dg (kn/m 3 ) σ c (MPa) PLS (MPa) P a 50 (kn) LA (%) Id 2 (%) Swelling strain ( l/l.10-4 )

12 Click to add title INDEX-PROPERTY ANALYSIS >Reduced number of basalt samples were tested; this type of material was the one exhibiting the best mechanical characteristics of rockfill materials. >The same class number of each different lithologic type roughly present identical structural behaviour in rockfills. >Those limits should therefore be taken into account in the analysis of results of new tested materials of the same type of rock.

13 COLLAPSE Click to IN add ROCKFILLS title Collapse in rockfills occurs when there are volumetric deformations by compression, due to the decrease in the strength of rock fragments in contact with water; collapse is related with the crushing of particles. Limit relation of the potential collapse CARBONATE ROCKS GREYWACKE ROCKS σ c sat/σ c dry (%) GRANITIC ROCKS PLS sat/pls dry (%) Pa50 sat/pa50 dry (%) Id 2 dry/ Id 2 sat (%) A rock sample is water sensitive when the values of the relations of index- -properties in tested fragments, both in saturated and in dry states, are less than those indicated in this table.

14 Click to add title General Reporter How do the stress strength index tests affect the mechanical properties of the rockfills?

15 P = k D 2 P a = η D Click to add title λ λ=1.5 Crushing Strength Contact Force Grain Breakage (B g ) Higher Crushing < φ / e < E oed

16 Click to add title General Reporter How can the index properties be used to help in the decisions of compaction procedures?

17 XINGÓ DAM Sluicing 1989 Click to add title Granites

18 Madeira Airport 1995 Density and grain size tests Click to add title Index tests

19 Madeira Airport Density tests Test fills Click to add title Basalts Density tests

20 General Reporter The authors discussed Click collapse to add and title the correlations of index properties of different lithology. Could the authors have shown these correlations? Empirical Correlations between collapse and dam structural behaviour PM cota 45 PME PMD cota 54 cota 40 cota cota 56 m cota 56 j PJD PJE Y ESCALA: 0 ~150m - PILAR CONSIDERADO FIXO - PILAR ESTACIONÁVEL - PILARETE NÃO ESTACIONÁVEL ESCALA DOS DESLOCAMENTOS 0 1 cm X

21 CONCLUSIONS Click to add title > The type of rock affects greatly the mechanical behaviour of rockfill materials. > Index-properties tests can allow to estimate the mechanical properties of rockfills. > The rockfills with better mechanical characteristics are, by decreasing order, as follows: basalt greywacke limestone granite schist > Limestone, greywacke and schist rock fragments must be tested to analyse the effect of collapse.

22 Thankyou Click to add title for yourattention! A. Veiga Pinto M. Quinta Ferreira Remember the benefits of the index properties!