Category: Civil Projects

The computation of the bearing capacity from field plate load test has already been discussed in the chapter of site investigation. Here, the discussion will be limited to the estimation of bearing capacity from the results of standard penetration test. Cohesionless soil – In cohesionless soils, the bearing capacity is extremely high with respect to shear failure criteria. In sands, the shear failure criteria govern the capacity only in the case of very narrow footing located in loose sand below water table. In most of the cases the bearing capacity…

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Skempton 1951 suggested a bearing capacity theory for saturated clay for which ɸ = 0. Skempton gives Nc, the bearing capacity factor on the basis of theory, laboratory tests and field observations. It was found that the value of Nc increased with the increase in Df/B ratio. The expression for Nc proposed by Skempton is given below. For Strip footings, Nc = 5(1+0.2Df/B), with a maximum limiting value of 7.5   ———- (1) For square and circular footings, Nc = 6(1+0.2Df/B), with a maximum limiting value of 9.0   ———-…

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Terzaghi has developed the bearing capacity equation on the assumption that water table is at great depths. If water table is present close to the foundation, some modification is necessary. This is done as per the followings. Case 1 Water table above footing base The weight of soil below water table is reduced due to buoyancy. The influence of water table on bearing capacity is incorporated in the general bearing capacity equation with the help of Fig.1. Let, Zw1 = Depth of water table below ground level a = Height…

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Terzaghi in 1943 gave a general bearing capacity theory for a strip foundation, called “Terzaghi’s Theory on Bearing Capacity Analysis“. For the first time, he developed his theory by incorporating the weight of the failure wedge in the analysis. Terzagi considered a continuous footing of width B placed at a depth of D below the ground surface as shown in fig.1. In the derivation of the equation, the following assumptions were made. The soil is homogeneous, isotropic and Columb’s law of shear strength is valid. The footing is continuous and…

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How to Development of equation of Bearing Capacity by Prandtl? equation of Bearing Capacity by Prandtl: As failure surfaces are symmetrical only forces acting on the right side of the wedges are considered. According to Prandtl, the bearing pressure Qult acting at the base ab of the footing is transmitted through the soil wedge abc on to the face bc, according to the Pascal’s law, pressure is undiminished and same in all direction. The state of stress within the wedge on the line bc may be explained with respect to…

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Prandtl and Bell Theory on Bearing Capacity Analysis: Prandtl 1920 developed an equation based on his study of penetration of long hard metal puncher into softer materials for computing the ultimate bearing capacity. Assumptions made by Prandtl and Bell Theory on Bearing Capacity Analysis The material is softer, homogeneous and isotropic. The material is weightless and possesses only friction and cohesion. The problem is two dimensional The base of the puncher is smooth. The material behaves as a rigid body. The volume change will be Zero. The resulting deformation will…

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Bearing Capacity Analysis | Pauker – Rankine Method The methods suggested by Pauker Rankine Method are based on theory of classical earth pressure. This was postulated by Pauker a military engineer in 1850 and then modified by Bell in 1915. Pauker’s theory is only applicable to sands. Bell extended this theory for cohesive soils. Both the theories have not taken into account the width of the foundation. Since the equation has been developed based on Rankine’s earth pressure theory, the theory is called as Rankine’s theory for the determination of…

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