The first one I managed to recreate with the zig zag (smooth) function, but as soon as there are more curves that run parallel to one another, I can't seem to make it work anymore. The curves / waves should be running like a train track, where the inner waves are adjusted to remain parallel with the outer waves. Right now they are the same size and therefore will run into one another in the corners - see my failed attempt below. Adjusting the zig zag size does not seem to work due to that it doesn't allow me to only slightly adjust it (e.g. setting 1.5 will automatically round up to 2).
There's an offset path effect that will do this correctly. Start by drawing the middle path, expand it and use the offset path effect to create the other lines, with positive or negative offset values. Expand the results so that you can edit the paths separately.