differences than noted would occur if bubbles were a problem. ) 

 The second important observation, from the e-log a data, 

 is that the curve does not become a straight line at higher pressures 

 as is usually the case (Reference 33, p. 217). Other researchers 

 have found similar behavior in calcareous material [11, 12], while 

 a third paper indicates no continuing curvature [10]. It has been 

 suggested [34] that the effect could be due to the extrusion of 

 material past the porous stone at higher pressures; this possibility 

 is being examined. Volume change versus pressure data are by convention 

 quantified in terms of the slopes of straight line approximations 

 to the e-log 'a curve. The slope of the straight line approximation 

 to the latter part of the curve during loading is called the compression 

 index, C^, ; and the slope of the curve during unloading is called 



the swelling index C . (See Figure 12.) 



s 



The compression index for the two tests on natural calcareous 

 ooze was about 0.80 and the swelling indices were 0.036 and 0.056. 



Predictive Capability. Various relationships have been used 

 to estimate the compression index, C , for clays. Terzaghi and 

 Peck suggest the relationship 



C =0.009 (w, - 10) (Reference 35) 

 c L 



which, assuming an average liquid limit, w^, of 68 for the calcareous 

 ooze, would indicate a C^, of 0.52 (65% of that measured). A relation- 

 ship suggested by Herrmann, et al., 



C =0.011 (w - 12) (Reference 36) 



C L 



yields a calculated C^. of 0.62(77% of that measured). These calculated 

 values of Cc compared to the measured value of 0.80, suggest that 

 the ^calcareous ooze tested is more compressible than a typical 

 clay-type soil having the same liquid limit. On the other hand, 

 other recommended empirical relationships for C , based on initial 

 void ratio or on water content, were tested for this calcareous 

 ooze with opposite results. Reference 37 (p. 7-3-12) recommends: 



C = 0.54 (e - 0.35) 

 c o 



which for a void ratio, e = 2.71 yields C = 1.27 and 



o c 



C = 0.0054 (2.6 w - 35) 

 c 



which for a water content, w =97.7%, yields C^ = 1.18. These calculated 



