what threetricks does rainsford use to elude Zaroff?

Aside from the initial doubling back several times to confuse the path and then hiding in a tree (an attempt that does not work because Zaroff is just playing with Rainsford), Rainsford develops three traps to escape Zaroff.  First, Rainsford rigs a trap that when Zaroff trips it, a dead tree will fall on the latter.  When that does not work, Rainsford then digs a pit with sharp sticks in the Death Swamp, and covers the opening with branches and weeds.  The second trap fails as well, killing only one of Zaroff's dogs, so Rainsford attempts a third method:  he affixes a knife to a sapling, to cut Zaroff when he follows the path.  However this fails as well, killing Ivan instead of Zaroff.  Yet, Zaroff manages to avoid all three tricks.