Passive thrust coefficient
Introduction
Lateral ground pressure is the pressure that the ground exerts in the horizontal plane. The most common applications of the theory of lateral pressures in soils are the design of foundation structures such as earth walls, footings, tunnels and to determine the ground friction on the surface of deep foundations.
To describe the pressure that a soil can exert, a lateral pressure coefficient "Coefficient (mathematics)") is used, K. K is the ratio between the lateral or horizontal pressure with respect to the vertical pressure (K = σ'/σ'). This formula is assumed to be directly proportional and is true at any point on the ground. K may depend on the mechanical properties of the soil and the stress history of the soil. Lateral pressure coefficients can vary within three categories: resting pressure, active pressure, and passive pressure.
Pressure coefficients are used in geotechnical engineering analysis depending on the characteristics of their application. There are many theories to predict lateral pressure, some empirical and others analytical.
Resting pressure
The pressure at rest, represented by K, is the horizontal pressure of the ground. This can be measured directly by the dilatometric test (DMT) or by a borehole pressuremeter test (PMT). These tests are expensive, which is why empirical relationships are used to predict the rest of the pressures that are more difficult to obtain and generally depend on the angle of internal friction. Some formulas are:
Jaky (1948)[1] for normally consolidated soils:.
Mayne & Kulhawy (1982)[2] for overconsolidated soils:.
The latter requires a deep OCR profile to determine.
Active and passive pressure
Contenido
El estado activo ocurre cuando existe una relajación en la masa de suelo que lo permite moverse hacia fuera del espacio que limitaba la tensión del suelo (por ejemplo un muro de tierra que se rompe); esto es que el suelo está fallando por extenderse. Esta es la presión mínima a la que el suelo puede ser sometida para que no se rompa. Al contrario el estado ocurre cuando la masa de suelo está sometida a una fuerza externa que lleva al suelo a la tensión límite de confinamiento. Esta es la máxima presión a la que puede ser sometida un suelo en el plano horizontal.