She braved the wilderness ... but former "Survivor" contestant Semhar Tadesse was no match for the tacky carpet in her L.A. apartment ... snagging her heel and breaking her foot ... and now she's suing her landlord.

Making matters worse, sources tell TMZ the fall took place on the staircase back in August ... and we're told Semhar broke two bones in her foot.

Semhar filed a lawsuit in L.A. County Superior Court, claiming the injuries were so serious .... she couldn't work. Sources say her medical bills are already north of $20k.

Two months after the fall, Semhar was arrested for DUI -- she previously told TMZ, the only reason she bombed her field sobriety test was because of her injured foot, which prevented her from walking a straight line.

Semhar's suing for undisclosed damages. Calls to her old landlord weren't returned.

"Survivor" cast-off Semhar Tadesse just admitted in open court ... she was three sheets to the wind when police arrested her for DUI last October -- and now, she's ready to face the music.

TMZ broke the story ... cops pulled over 25-year-old Semhar after she ran a red light -- then arrested her on suspicion of drunk driving ... after she bombed a field sobriety test.

Semhar pled guilty today to misdemeanor DUI -- and was sentenced to 3 years probation. In addition, Semhar was ordered to attend an alcohol education program, and pay a $1,827 fine.

Don't drink and drive, kids.