The most mountainous stage Le Tour was won by another of Froome's former teammates, Cannondale-Drapac's Rigoberto Uran, with the Team Sky man finishing third, in the same time as the Colombian.
Froome retains the overall lead from Italy's Astana rider Fabio Aru by 18 seconds and Frenchman Romain Bardet (AG2R La Mondiale) by 51.
The Australian rider reportedly braked to avoid the wheel of another rider and subsequently missed a downhill left-hand bend, leaving the sealed road, cartwheeling back across the bend and bowling over Dan Martin, before hitting a grassy bank.
Martin, who was able to continue following the crash only to be involved in another one further down the road (he eventually finished the race), said that Porte was the victim of a slippery corner.
Thomas started the day 12 seconds adrift of Team Sky team-mate Froome in second spot in the GC standings, but his race was ended when he damaged his shoulder in a fall.
Quintana and Spanish veteran Alberto Contador (Trek-Segafredo) had both been dropped by the favourites on the seventh and final climb of the day following a series of attacks from Froome and Porte on the Mont du Chat - making its first appearance on the race since 1974.
The tour takes a rest day on Monday, ahead of stage 10 on Tuesday.
Geraint Thomas has spoken of his devastation at crashing out of the Tour de France, but has backed Team Sky to regroup and "do a great job for Froome". "It wasn't a swipe at Aru or anything like that".
"Richie just lost it on one corner", he said. "It is so slippery".
At that moment Aru, from well back amongst the group of leaders, put in a burst that left Froome trailing. Even though he crashed a second time on that descent, he had only lost 1 minute 15 seconds by the end of the stage. As Froome raised his right arm to signal for his team auto, Aru, on his wheel, surged ahead, literally under Froome's armpit, with Nairo Quintana attached.
Two years later, during his first season with BMC, Porte suffered a puncture on an early stage of the Tour.
"When we knew we had the problem with the rear derailleur, first we made the decision to go to the line with the bike like that", said head sport director Charly Wegelius. It's a huge surprise for me. But the dauphin Froome in the Tour in 2016 has been taken on the part of dish (13 km), leading to Chambéry, at the threshold of the final two kilometres.
Then, during a risky, technical descent on Sunday's stage nine, Richie Port had a horrific crash, suffering a broken shoulder and pelvis. "Gave everything there, rode with the other guys like it was a team time trial and tried to salvage as much as I could", explained Martin after his awesome all-out effort, which sees him go into the second week of the Tour de France in sixth overall.style="text-align: center;"