Is pore compressibility in TOUGH2 not identical to bulk compressibility(1/K)?

Hello.

Recently, I am trying to solve 1-D consolidation problem(Terzaghi's) with TOUGH-FLAC.

In order to solve it, I first run FLAC to consider pore pressure generation(Skempton's effect).

The results of Flac are used as TOUGH2 input(INCON) and then I run TOUGH and TOUGH-FLAC, respectively.

In the simulations, I don't consider indirect coupling(no porosity changes due to strain or stress)

That's why they give same results, but don't agree with analytical solution.

Pressure diffuses faster than the analytical solution.

Because diffusion of pressure depends on hydraulic diffusivity(function of(Perm, compressibility of fluid and matrix )), I handled the pore compressibility in TOUGH2.

If I used 4 times the compressibility, the results very agree with analytical solution.

it is very strange....

Surprisingly, this problem arises in TOUGH2-EGS-MP's verification example

I got TOUGH2-EGS-MP USER’S GUIDE, they also solved 1D problem to verify the model(TOUGH2-EGS-MP).

I found that they also used  4 * bulk compressibility not bulk compressibility.

So is pore compressibility in tough 4*bulk compressibity?

I attached two pictures for understanding.

Thanks

Sungho