**Teng’s method** – Teng (1962) based on the work of Terzaghi and Peck gave a relationship for allowable bearing capacity for a given permissible settlement.

The equation is:

q_{ns} = 35(N-3){(B+0.3)/2B}^{2}R_{W}R_{d} ———- (1)

Where, q_{ns} = Net safe bearing pressure, kN/m^{2}

N = SPT value corrected for overburden pressure

R_{W} = Water table correction factor

R_{d} = Depth correction factor = 1 + 0.2D_{f}/B â‰¤1.2

The above equation can also written in general form as:

q_{ns} = 1.4(N-3){(B+0.3)/2B}R_{w}R_{d}S ———- (2)

Where, S = Permissible settlement in mm.

**Meyerhof’s method** – Meyerhof (1965) suggested the following procedure to obtain allowable bearing pressure to give a settlement of 25 mm.

**Procedure:**

- N value should not be corrected with respect to overburden.
- q
_{a}is obtained from the chart shown in fig.4.11. - q
_{a}should not be corrected against ground water table. - Multiply q
_{a}by 150 %.

The equation proposed by Meyerhof (1974) is slightly different from Tongs equation. The equation proposed is:

q_{ns} = 12NR_{w}R_{d} for B â‰¤1.2m ———- (3)

q_{ns} = 8N{(B+0.3)/B}^{2}R_{w}R_{d} for B>1.3 m ———- (4)

Where, q_{ns} = Net safe bearing pressure, kN/m^{2}

N = SPT value corrected for overburden pressure

R_{w} = Water table corrected factor

R_{d} = Depth correction factor = 1 + 0.33D_{f}/B â‰¤1.33

**Bowles method** – The equation proposed by Meyerhof and Tong were found to be very conservative and Bowles (1982) modified these equations. The equations proposed are:

Teng’s modified equation,

q_{ns} 53(N-3){(B+0.3)/2B}^{2}R_{w}R_{d} ———- (5)

Meyerhof’s modified equation,

q_{ns} = 20NR_{W}R_{d} for â‰¤1.2 m and ———- (6)

q_{ns} = 12.5N{(B+0.3)/B}^{2}R_{W}R_{d} for B>1.3 m ———- (7)

Where, q_{ns} = Net safe bearing pressure, kN/m^{2}

N = SPT value corrected for overburden pressure

R_{W} = Water table correction factor

R_{d} = Depth correction factor = 1+ 0.33 D_{f}/B â‰¤ 1.33.

The value of bearing capacity factors are found out from the graph as shown in Fig.2 above. It is for mix shear condition. The values of N_{Î³} and N_{q} are used to bearing capacity of granular soil on the basis of shear failure criteria.