Can someone explain me these waveforms?
I'm only going to show what happens when the load is a capacitor. There are enough clues in this answer (and previous comments) to relate to the scenario when an inductor is the load.

To answer this properly and make it useful to others you have understand what happens at the sending end when the reflected pulse returns. For the capacitor load it is useful to consider (as a reminder) what happens when the t-line load is a true short circuit: -


If we replace the shorted end termination with a 500 pF capacitor we see this: -

So the capacitor-reflected pulse initially has exactly the same form as when the line was terminated in a short (at t = 200 ns). This is because when the pulse arrives at the load, the load (a 500 pF capacitor) initially behaves like a short circuit.
However, pretty immediately the capacitor starts converting the received pulse from the sending end into the blue voltage waveform seen in the image below. This waveform is reflected back to the source but it's initial value has to be -2.5 volts and so, if I mess around with this picture using &quot;paint&quot; I can start to build up what happens at the sending end when the reflection comes back from the capacitor: -

Of course, when the initial pulse ceases (after 50 ns) the capacitor at the end of the t-line starts to discharge but there is also a reflection &quot;recoil&quot; and a sharp rise of 2.5 volts is seen in the reflected voltage. The &quot;recoil&quot; happens because the 50 ns pulse is &quot;spent&quot; and this produces a near-instant rise in the reflected voltage. From that point onwards in time, the reflected waveform follows the capacitor discharge curve.

Micro-cap simulation file available on request. Transmission-line modeled as 20 metres of loss-less line with C = 100 pF/meter and L as 250 nH/metres. Source-end driven with a 5 volt pulse of 50 ns duration via 50Ω.