Samson's superhuman strength transforms a carefully laid Philistine trap into an unprecedented display of power. The Philistines assume that their massive city gate, a heavy structure built to withstand a military siege, will serve as an impassable barrier [ביאור שטיינזלץ].
Waking at midnight, Samson finds the gates securely locked [מצודת דוד]. Instead of merely breaking the lock to escape, he chooses to confront the massive obstacle in its entirety. Grabbing the doors and uprooting them whole requires far more strength than simply shattering the bar that holds them shut [מלבי"ם]. He takes hold of the doorposts as well, pulling the large pillars from both sides of the entrance [מצודת ציון].
The primary approach among commentators is that he forcefully tears the entire gate system from its foundation [רש"י, מצודת דוד, מצודת ציון]. Others, however, emphasize the sheer ease of the action: Samson simply begins to walk, and his forward movement effortlessly uproots the gates, carrying them along with him [רד"ק, מלבי"ם]. The entire structure is pulled from the ground with its bar still intact, leaving the heavy doors locked firmly together [מצודת דוד, ביאור שטיינזלץ].
To complete this feat, Samson lifts the enormous load onto his shoulders. He carries it for a vast distance, walking a full day's journey from Gaza all the way to the mountain facing Hebron [מלבי"ם]. There, he leaves the heavy gates on public display [ביאור שטיינזלץ]. From the initial uprooting to the long journey with such a massive weight, the entire sequence highlights his unique and immense physical power [רלב"ג].