Drained test, long time

The long-time drained (or ``jacketed'') test for a double-porosity system should thus correspond to the condition $\delta p_f^{(1)} = \delta p_f^{(2)} = 0$ so that the total volume obeys $\delta e = - a_{11}\delta p_c$. It follows therefore that  

$$a_{11} \equiv {{1}\over{K^*}}.$$ (19)