I have 3 torts, an adult male, an adult female and a 9 year old I suspect is female.
When I put the female and the youngster together, the female seems fascinated by the little one. She smells it intently for several minutes, then will begin shoving it around just like a bulldozer. Eventually she will get the smaller one shoved into a corner and keep plowing into it over and over.. The little one does not return the attention or agression, she just kind of "takes it".
What's going on here? I have heard that males will fight, but I have never heard of that behavior from females....
Its just a "top dog" thing. Your older female is telling the youngster that this is her territory and if she knows what's good for her she'd better high-tail it out of here. Do you have lots of sight barriers in their pen? You need to provide different places for the youngster to get out of the older female's sight. They will eventually settle down and live peacefully together, but in the meantime you don't want the youngster to be injured.
I bought a hatchling Manouria emys phayreii about 11 years ago and it was kept separate from the larger group. Last summer I figured the baby was big enough to be integrated into the "flock," but my dominant female had other ideas about that. She did just what you described, only it lasted all day long. I finally had to remove the younger female. The way I got around the grumpy female was to add the 6 young males from another pen into the grumpy female's pen. She was so busy chasing all six of those young males that she forgot about the young female, who is now a happy part of the herd!
Yvonne
I have 3 torts, an adult male, an adult female and a 9 year old I suspect is female.
When I put the female and the youngster together, the female seems fascinated by the little one. She smells it intently for several minutes, then will begin shoving it around just like a bulldozer. Eventually she will get the smaller one shoved into a corner and keep plowing into it over and over.. The little one does not return the attention or agression, she just kind of "takes it".
What's going on here? I have heard that males will fight, but I have never heard of that behavior from females....
I had to laugh when I read your post, I'm new to the site and I came across your post and I have a adult female that did the same things this spring to a new arrival from my Dad's group. Wilbur (female) did not like the new female and I thought it to be funny that two females would act that way, I only knew of males acting this way. In the end I had to take back the new female back to her old home and bring a male back. Needless to say Wilbur is digging and getting ready to lay eggs. Her first clutch. I have had her since she was a hatchling when I was a kid. Wilbur is twenty five years old now. 
I have also had the same experience but it was with my adult female Dolly and a juvenile that is her offspring and much smaller. When I adopted them I thought it would be fine to house them together but my female Dolly did not want Peanut in the enclosure and I felt so bad because I came out to check on them and Dolly had bit Peanuts front legs so bad she took off the top layer of scales and they were bleeding. Poor Peanut was just closed up in her shell with her legs covering her face to protect herself.