2.10 Bearing Capacity Capacity in bearing capacity indicates that it is an ultimate concept and it is not a safe or working or allowable quantity. Bearing capacity refers to the ultimate, the maximum load the soil can bear or sustain under given circumstances. Therefore, it involves the application of loads to the soil for which a medium such as a footing is needed whose role is to invoke the property latent in the soil called its bearing capacity. The bearing capacity of soil is concerned with strength of soil and not that of footing. Therefore, in all bearing capacity discussions only footings which are infinitely rigid and which can bring about the failure of soil without itself failing are considered. In other words the footing just plays the role of a medium to load the soil. SOIL TYPE BEARING CAPACITY() REMARKS Dense gravel or sand and > 600 gravel B should not be less than 1m. Medium dense gravel or sand 200 600 – and gravel Water table below foundation Loose gravel or sand and < 200 level. gravel Dense sand > 300 Medium dense sand 100 - 300 Loose sand < 100 Very stiff and hard clays 300 - 600 Long term consolidation Stiff clays 150-300 settlement Firm clays 75 - 150 Soft trial and silts < 75 Very soft clays and silt <<< 75 Table 2-2: Bearing Capacity Ranges of Soils 2.11 Soil Mechanics and Foundation Engineering Foundations pass the load from a structure to the ground by direct contact. The load from the superstructure reaches the foundation by means of a number of individual units such as columns or walls and it is the function of the foundation to distribute the load in such a manner that the ground is neither over stretched nor caused to settle more than the superstructure can conveniently accommodate. Karl Terzaghi’s writing in 1951 influence “the
2.10 Bearing Capacity Capacity in bearing capacity indicates that it is an ultimate concept and it is not a safe or working or allowable quantity. Bearing capacity refers to the ultimate, the maximum load the soil can bear or sustain under given circumstances. Therefore, it involves the application of loads to the soil for which a medium such as a footing is needed whose role is to invoke the property latent in the soil called its bearing capacity. The bearing capacity of soil is concerned with strength of soil and not that of footing. Therefore, in all bearing capacity discussions only footings which are infinitely rigid and which can bring about the failure of soil without itself failing are considered. In other words the footing just plays the role of a medium to load the soil. SOIL TYPE BEARING CAPACITY() REMARKS Dense gravel or sand and gravel > 600 B should not be less than 1m. Water table below foundation level. Medium dense gravel or sand and gravel 200 – 600 Loose gravel or sand and gravel < 200 Dense sand > 300 Medium dense sand 100 - 300 Loose sand < 100 Very stiff and hard clays 300 - 600 Long term consolidation settlement Stiff clays 150-300 Firm clays 75 - 150 Soft and silts < 75 Very soft clays and silt <<< 75 Table 2-2: Bearing Capacity Ranges of Soils 2.11 Soil Mechanics and Foundation Engineering Foundations pass the load from a structure to the ground by direct contact. The load from the superstructure reaches the foundation by means of a number of individual units such as columns or walls and it is the function of the foundation to distribute the load in such a manner that the ground is neither over stretched nor caused to settle more than the superstructure can conveniently accommodate. Karl Terzaghi’s writing in 1951 “the influence trial