Can I tape rather than glue buried PVC conduit to make pulling wires easier?

First off, you're not allowed to assemble conduit around cable. It has to be a continuous run assembled to specs. You'd be surprised and how many bends you can pull through with stranded THHN wire when you need to replace it. If you know the cable is bad, you might want to think about replacing it now while you're doing all the rework. Just a thought.

This sounds like you don't know much about conduit, and you're proceeding anyway, which will produce a homebrew hatchet job. Don't do it. Follow Code, and skill up as needed.

PVC conduit must be buried with 18" of cover. If you don't want to dig that far, use Rigid Metal Conduit (RMC or IMC) which requires 6" of cover. Cover means dirt on top of pipe.

I don't really care if PVC is glued (Code disagrees). Water WILL get in. However, you'll want to glue it in the places where pulling forces will tend to pull it apart. The PVC needs to be stoutly anchored so pulling forces move the wire instead of move the conduit.

You must use outdoor rated wire for runs outdoors in conduit. Water WILL get in, can't be avoided; one outfit laid a conduit for a race-track in high ground (well above the water table). Sealed well, no rain, but the next day they pulled over a gallon of water out of the pipe. Condensation.

You are not allowed to use PVC water pipe for electrical, it must be PVC electrical conduit. They don't make tight bends for that, they only make broad sweeps and conduit bodies. ...That tells me the "the multiple tight bends I need to implement" refer to either plumbing elbows, or improper use of conduit bodies. I've seen somebody push a "pulling elbow" type conduit body into a corner, access panel facing the wall, because the person was unaware of the existence of either sweeps or LR conduit bodies, or the purpose of that access cover.

To repeat, conduit must be pullable! Don't build anything you can't pull wires into later!

You must assemble the entire conduit COMPLETE before pulling any wires into it. Needless to say, the cheesehead who faced the pulling elbow into the wall assembled the conduit around the wires. Had to redo all of it, and had to scrap expensive wire since it was glued. If that's your motivation for trying to avoid gluing, then reboot your thinking about how conduit works.

As far as pulling around "multiple tight bends", you are only allowed four 90 degree sweeps in between pulling points such as conduit bodies or junction boxes. You MUST make full use of pulling points; you cannot pull around their corners (that will shred the wire insulation). Further, all pulling point covers must be accessible at all times forever without removing any building finish or disassembling any part of the building. You are allowed to block them in with movable things like file cabinets, but not built-in cabinets.

If you are doing everything right and are still concerned with pulling forces being excessive, then I have several tips.

• Use individual wires, NOT cable. A very common "conduit novice" move is to believe that the only type of electrical wire is cable, and therefore, try to chicken-choke cables down conduit. This is legal, but really, really hard.. and this difficulty is likely to fail the project and force them to bring in a real electrician with a truck full of pulling tools. Pros don't pull cables, they pull individual wires. Next time you're at a home store, find a spool of #12 stranded THHN. Wouldn't you rather pull four of those? :) Yeah :) Also, these individual wires take much smaller conduit - 6/3 UF requires 2" conduit, four THHN wires fit in 3/4" conduit.
• Use stranded, not solid. All else being equal, #12 stranded THHN is much easier to pull than #12 solid THHN. Yes, it's a PitA to put on screw terminals; don't - pigtail it to solid.
• Use fewer sweeps. Code requires no more than four 90 degree sweeps between pulling points. For novices I strongly recommend 1 or at most 2. (pretty much can't avoid 2 on an underground run).
• Use bigger conduit. The same wire will pull easier in a larger conduit - i.e. don't push the limits of conduit fill. If you are forced into multiple sweeps underground, go extra bigger. Nobody ever wrote in here going "I need bigger feeder wires to my outbuilding, but my conduit has plenty of extra room. What do I do???"