CRITICAL NONDIMENSIONAL PARAMETERS FOR FOUNDATIONS ON GEOGRID-REINFORCED CLAY (Φ = 0 CONDITION).

Large-scale field and small-scale laboratory model tests results relating to the determination of bearing capacity of foundations supported by saturated clay are relatively scarce. Shin et al. [10] reported some laboratory model test results which were intended to determine the nondimensional parameters as defined later.  These tests were conducted with a continuous surface foundation (Df  = 0; B/L = 0) supported by a saturated clay having a liquid limit of 44% and a plasticity index of 20%. TENSAR BX1100 geogrid was used for reinforcement. Based on this study, the following conclusions were drawn:

1. For all cases

2. (u/B)cr = 0.4. This fact is illustrated in Fig. 7.23. Note that, for all b/B values, the magnitude of BCR increases from u/B = 0.25 to u/B = 0.4 and decreases thereafter.

3. (u/B)max = 0.9 to 1.0.

4. Critical-width ratio:  (b/B)cr = 4.0 to 4.5.  This can clearly be seen from Fig. 7.23.

5. Critical reinforcement-depth ratio:  (d/B)cr = 1.8.  This is illustrated in Fig. 7.24. Note that (d/B)cr
 is independent of the undrained cohesion of the clay, cu.

FIGURE 7.23  Variation  of  BCR  with  B/B  (after  Shin  et  al.  [4])     
( Note:  h/B = 1/3 and N  = 4)


FIGURE 7.24  Variation  of  BCR  with  N   (that  is  d/B) (after  Shin
et al. [4]) ( Note:  b/B = 4, u/B = 0.4, h/B = 1/3)

REFERENCES.


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