What is the coefficient of active earth pressure?

Active earth pressure coefficient (Ka): It is the ratio of horizontal and vertical principal effective stresses when a retaining wall moves away (by a small amount) from the retained soil. K a = 1 − sin ⁡ ( ϕ ) 1 + sin ⁡ ( ϕ ) = tan 2 ( 45 − ϕ 2 ) .

How do you calculate the coefficient of active earth pressure?

The principle of determination of active earth pressure is to multiply the effective vertical stress with the lateral pressure coefficient (Ka) and then add the hydrostatic pressure due to water table, if any.

What is active lateral earth pressure?

Lateral earth pressure is the pressure that soil exerts in the horizontal direction. Active Earth Pressure Active earth pressure occurs when the wall tilts away from the soil. (for example a typical free standing retaining wall) • In Active earth pressure the value of K is minimum.

What is Dynamic earth pressure?

Dynamic Earth Pressures on Retaining Walls. o Design of retaining wall under seismic condition is very important in earthquake prone areas to reduce the devastating effect of earthquake. O Evaluation of earth pressure under seismic condition is important.

What is active earth pressure in civil engineering?

NOTE:Active and passive earth pressures are the two stages of stress in soils which are of particular interest in the design or analysis of shoring systems. Active pressure is the condition in which the earth exerts a force on a retaining system and the members tend to move toward the excavation.

How do you calculate K0?

The K0 was measured using Marchetti (1980) flat dilatometer. The measured KD according to Marchetti (1980) was 8.0 and K0 derived using the empirical equation K0 = (KD/1.5)0,47 – 0.6 was K0 = 1.6.

What is difference between active and passive earth pressure?

Active pressure is less than resting pressure, while passive pressure always exceeds resting pressure. Practically, some centimeters movement is sufficient to completely realize passive pressure; as well as practically not any retaining wall undergone active pressure remains completely immobile.

What is active and passive lateral earth pressure?

Active pressure is the condition in which the earth exerts a force on a retaining system and the members tend to move toward the excavation. Passive pressure is a condition in which the retaining system exerts a force on the soil.

Is the Earth static or dynamic?

Earth is a Dynamic Planet Change is perhaps the only constant in our planet’s history. Since the Earth’s beginning about 4.5 billion years ago, natural climate and environmental conditions on our planet have been in constant flux.

What is K0 in Geotech?

The at-rest earth pressure coefficient K0, i.e. the ratio σ′h /σ′v between the horizontal and the vertical effective geostatic stresses at a point in a semi-infinite soil mass bounded by a horizontal plane, is a fundamental parameter in soil mechanics.

Which is the best method to calculate active seismic pressure?

The simplest method to approximate seismic active pressure is to use the approach of Mononobe-Okabe (M-O) which is originally based on Coulomb’s theory of static earth pressures. The method incorporates the following assumptions ( Geraili and Sitar, 2013 ):

How is the M-O seismic pressure method modified?

The M-O method was modified by Seed and Whitman (1970) for easier application in the practice. They proposed to separate the M-O seismic active pressure into two components; (i) active static component ( ).

How is cohesion related to seismic earth pressure?

However, most natural deposits have some fines content that exhibits some degree of cohesion ( Sitar et al., 2012 ). Anderson et al. (2008) found that the contribution of cohesion to a reduction in seismic earth pressure on retaining walls could be in the order of approximately 50%.

Who is the inventor of seismic earth pressure?

Pioneering works on seismic earth pressure on a rigid retaining wall have been reported by Okabe (1924) and Mononobe and Matsuo, 1929, Mononobe and Matsuo, 1932. Their analyses have provided a popular solution to the problem of cohesionless soils.