If we have a closed curve then the line integral for work is just zero.

如果给定一条封闭曲线，那么求所做功的线积分为零。

youdao

At that time, the slope of stress-strain curve of the rock is zero.

此时岩体应力—应变曲线的斜率为零。

youdao

At that time, the slope of stress-strain curve of the rock is zero.

此时岩体应力—应变曲线的斜率为零。

youdao