I was having a confusion in deciding how many layers of each material is to be used and the thickness of each layer.

Well you need the materials - whatever they are - to perform two functions:
a. Be tough to withstand colliding debris.
b. Block out harmful rays.

From the materials you have researched, select a material that can serve both the purposes, so that you can employ mass production techniques and get economies of scale.

Now, the total thickness of a particular 'glass' will depend on two things:
1. Its impedance.
2. Its absorption factor. Simple concepts see A Level Physics application booklet and read the ultrasound section. I think that the equations will work for EMR too.

Now here is what you have to do:

Step 1: Find out the magnitude of the maximum intensity UV/X-rays that you can receive. As I said in my earlier post, these will accompany Coronal Mass Ejections and Solar Flares. Google for numerical data.

Step 2: Find out the maximum intensities humans/animals/plants can tolerate for a 48 hour   exposure time -- or the time for which typical CME lasts minus the time for which your colony will not be facing the sun. Select the smallest of the three values.

Step 3: Subtract the reflected intensity using the impedance equation from the incident intensity. The value of the reflected intensity depends on the density of the material, not the thickness as this occurs at the interface of the two media.

Step 4: Secure the result from the above calculation. Now use the absorption
equation I=I(knot)e^-kx.

'I' is the output intensity that will reach the occupants of the dome. This will be the value from step 2.
'I(knot)' is the value from Step 3. This is the intensity of the wave that will travel through.
'K' is the absorption coefficient of the glass/material. Google this for your material;and finally,
'x' will be the thickness of the glass.

Solve for x, and verify the method+calculations.

Step 5: Once done, you can specify the standard thickness of a typical layer yourself after taking your construction machines' handling capacities into account. You can then calculate the number of layers by dividing X by that standard thickness.

The impedance equations that work for ultrasounds also work for electromagnetic radiation.
The density of the layer is constant i.e one type of material is being used.)