Line Load and Strip Load

Q. An isobar is a line which connects all points below the ground surface at which

1. The local ground elevation is same
2. The settlement is same
3. The vertical stress is the same
4. The ground elevation is varying

Q. A line load of infinite length has an intensity q per unit length. What is the vertical stress ${\sigma }_z$ at a depth z below the earth at the centre of the load?

1. ${\sigma }_z=\frac{2qz}{\pi }$
2. ${\sigma }_z=\frac{2q}{\pi z}$
3. ${\sigma }_z=\frac{2q{z}^2}{\pi }$
4. ${\sigma }_z=\frac{2q}{\pi z^2}$

Q. If vertical stress at the centre of $4m\times 6m$ rectangular strip is 80 MPa. What will be the stress below the corner of rectangular strip of (area) $2m\times 3m$

1. 40 MPa
2. 20 MPa
3. 160 MPa
4. 320 MPa