Issue 8

A. Namdar, Frattura ed Integrità Strutturale, 8 (2009) 21-29 ; DOI: 10.3221/IGF-ESIS.08.02 23 Figure 4 : Transducer position Three different types of models have been developed. The first model is loose sandy embankment and loose sandy saturated subsoil. It consists of dense wall made up from composite material (60 % sand and 40 % gravel) confined in geo textile installed outside toe of embankment . The second model is loose sandy embankment and loose sandy saturated subsoil consists of dense wall made up from composite material (60 % sand and 40 % gravel) confined in geo textile installed inside toe of embankment . The third model is loose sandy embankment and loose sandy saturated subsoil made up from composite material (60 % sand and 40 % gravel) confined in geo textile centrally installed on the toe of embankment. (Figs. 1-3 ). Fig. 4 shows the cross section of ground and water level with positions of acceleration transducers in the model. The horizontal shear strain γ is obtained from the differential displacement between two adjacent accelerometers, as illustrated in Fig. 5. It is given by γ = h d ∆∆ / where d ∆ = differential horizontal displacement between two adjacent points h ∆ = Distance between the two acceleration points max τ Figure 5 : Key sketch for the computation of shear stress and shear strain in the embankment (a = Acceleration, d = Corresponding displacement). Displacement can be obtained by double integration of the acceleration records. In a sand deposit, let’s consider a column of soil of height ‘h’ and unit area of cross section subjected to maximum ground acceleration a max . Assuming a soil column to behave as a rigid body, the maximum shear stress max τ at a depth ‘ h ’ is given by: { } τ γ = ∑ max max / s h g a where g = Acceleration due to gravity γ s = Unit weight of soil