# Tag: Soil Hydrostatic and Soil Pressures

Structures used to retain water, such as dams and tanks, as well as coastal structures partially or fully submerged in water must be designed to resist hydrostatic pressure. Hydrostatic pressure acts normal to the submerged surface of the structure, with its magnitude varying linearly with height, as shown in Fig. 2.9. Thus, the pressure at a point located at a

View Article...

# Tag: Soil Effect of Soil Compressibility on Bearing Capacity of Soil

Terzaghi (1943) developed Eq. (12.6) based on the assumption that the soil is incompressible. In order to take into account the compressibility of soil, he proposed reduced strength characteristics c and 0 defined by Eq. (12.11). As per Vesic (1973) a flat reduction of 0 in the case of local and  punching shear failures is too conservative and ignores the existence of

View Article...

# Tag: Soil Types of Failure in Soil

Experimental investigations have indicated that foundations on dense sand with relative density greater than 70 percent fail suddenly with pronounced peak resistance when the settlement reaches about 7 percent of the foundation width. The failure is accompanied by the appearance of failure surfaces and by considerable bulging of a sheared mass of sand as shown in Fig. 12.4(a). This type

View Article...

# Tag: Soil Density of soil

The term density is used herein to denote the mass-to-volume ratio of a material. However, some references, particularly older ones, use the term to describe unit weight. Density is denoted by p. Because m = W/g, the unit weight terms defined above can be converted to mass densities as follows: In the SI system mass densities are commonly expressed in

View Article...

# Tag: Soil Volume Relationships of soil

Volume relationships include the void ratio, the porosity, and the degree of saturation. The void ratio, denoted e, is the ratio of the volume of voids to the volume of solids: The degree of saturation, denoted S, is the ratio of the volume of water to the volume of voids. It is commonly expressed as a percentage: S = Vw / Vv x 100%

View Article...

# Tag: Soil The AASHTO Classification System

The AASHTO system classifies soils into seven primary groups, named A-1 through A-7, based on their relative expected quality for road embankments, subgrades, subbases, and bases. Some of the groups are in turn divided into subgroups, such as A-1-a and A-1-b. Furthermore, a group index may be calculated to quantify a soil’s expected performance within a group. To determine a

View Article...

# Tag: Soil Grain-Size Characteristics of Soils

Large-grained materials such as cobbles and boulders are sometimes considered to be soil. The differentiation of cobbles and boulders depends somewhat on local practice, but boulders are generally taken to be particles larger than 200 to 300 mm or 9 to 12 in. The Unified Soil Classification System suggests that boulders be defined as particles that will not pass a

View Article...

# Tag: Soil Soil-Structure Interaction Conclusions

Concluding the chapter about soil-structure interaction (SSI), the author should like to give several recommendations to engineers. 1. At the very beginning one should estimate the importance of SSI and decide whether it should be considered at all. The answer depends on the soil data (wave velocities in the soil, first of all), base mat size/embedment and inertia of the structure. For civil structures

View Article...

# Tag: Soil Soil non-linearity – SHAKE ideology – Contact non-linearity

Soil in reality is considerably non-linear. That is why H.B.Seed [23] suggested special method to describe seismic response of horizontally-layered soil to the verticallypropagating free-field seismic waves by equivalent linear model. Parameters of this model are obtained in iterative calculations, as modules and damping in each layer are straindependent. This method is used in the famous SHAKE code [24]. Usually 7-8 iterations are enough

View Article...

# Tag: Soil Impedance approach

If we presume the rigidity of the soil-structure contact surface and place surface Q in Fig.1 right at this surface, we get six degrees of freedom for Q. Corresponding forces F in “problem A2” are condensed to six–component integral forces, loading the immovable base mat during seismic excitation. In addition, when the mat moves, Vext impacts the moving base mat by response forces set

View Article...