Class Outline. • Retaining wall with friction. • Logarithmic spiral. • Determine the passive pressure. • Caquot and Kerisel (). • Passive force with on walls with. Lateral earth pressure is the pressure that soil exerts in the horizontal direction. The lateral .. In , Albert Caquot (–) and Jean Kerisel (– ) developed an advanced theory that modified Muller-Breslau’s equations to. Albert Irénée Caquot (1 July – 28 November ) was considered as the ” best living . Albert Caquot – Savant, soldat et bâtisseur», Jean Kérisel – August ; Bulletin of the SABIX, special number 28 about Albert Caquot.
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Lateral earth pressure is the pressure that soil exerts in the horizontal direction. The lateral earth pressure is important because it affects the consolidation behavior and strength of the soil and because it is considered in the design of geotechnical engineering structures such as retaining wallsbasementstunnelsdeep foundations and braced excavations. The effective stress is the intergranular stress calculated by subtracting the pore pressure from the total stress as described in soil mechanics.
K for a particular soil deposit is a function of the soil properties and the stress history. The minimum stable value of K is called the active earth pressure coefficient, K a ; the active earth pressure is obtained, for example,when a retaining wall moves away from the soil.
The maximum stable value of K is called the passive earth pressure coefficient, K p ; the passive earth pressure would develop, for example against a vertical plow that is pushing soil horizontally.
Lateral earth pressure
For a level ground deposit with zero lateral strain in the soil, caquor “at-rest” coefficient of lateral earth pressure, K acquot is obtained. There are many theories for predicting lateral earth pressure; some are empirically based, and some are analytically derived. At rest lateral earth pressure, represented as K 0is the in situ lateral pressure.
As these are rather expensive tests, empirical relations have been created in order to predict at rest pressure with less involved keriseel testingand relate to the angle of shearing resistance.
Two of the more commonly used are presented below. Jaky  for normally consolidated soils:. Although Jaky derived the above result using a theoretical model, the associated assumptions are not related to the physical problem. In this light, the good predictions provided by his solution are often viewed as lerisel coincidence.
The latter requires the OCR profile with depth to be determined. To estimate K 0 due to compaction pressures, refer Ingold . The active state occurs when a retained soil mass is allowed to relax or deform laterally and outward away from the soil mass to the point of mobilizing its available daquot shear resistance or engaging its shear strength in trying to resist lateral keriseel.
That is, the soil is at the point of incipient failure by shearing due to unloading in the lateral direction. It is the minimum theoretical lateral pressure that a given soil mass will exert on a retaining that will move or rotate away from the soil until the soil active state is reached not necessarily the actual in-service lateral pressure on walls that do not move when subjected to soil lateral pressures higher than the active pressure.
The vaquot state occurs when a soil mass is externally forced laterally and inward towards the soil mass to the point of mobilizing its available full shear resistance in trying to resist further lateral deformation. That is, the soil mass is at the point of incipient failure by shearing due to loading in the lateral direction.
It is the maximum lateral resistance that a given soil mass can offer to a retaining wall that is being pushed towards the soil mass. That is, the soil is at the point of incipient failure by shearing, but this time due to loading in the lateral direction.
Thus active pressure and passive resistance caqquot the minimum lateral pressure and the maximum lateral resistance possible from a given mass of soil. Rankine’s theorydeveloped in is a stress field solution that predicts active and passive earth pressure.
It assumes that the soil is cohesionless, the friction angle of the wall is equal to the inclination of the backfill i. The equations for active and passive lateral earth pressure coefficients are given below. Coulomb  first studied the problem of lateral earth pressures on retaining structures.
He used limit equilibrium theory, which considers the failing soil block as a free body in order to determine the keriseo horizontal earth pressure.
The limiting horizontal pressures at kerusel in extension or compression are used to determine the K a and K p respectively. Since the problem is indeterminate a number of potential failure surfaces must be analysed cawuot identify the critical failure surface i. Coulombs main assumption is that the failure surface is planar. Instead cawuot evaluating the above equations or using commercial software applications for this, books of tables for the most common cases can be used.
Generally instead of K athe horizontal part K ah daquot tabulated. The actual earth pressure force E a is the sum of the part E ag due to the weight of the earth, a part E ap due to extra loads such as traffic, minus a part E ac due to any cohesion present.
E ag is the integral of the pressure over the height of the wall, which equates to K a times the specific gravity of the earth, times one half the wall height squared. In the case of a uniform pressure loading on a terrace above a retaining wall, E ap equates to this pressure times K a times the height of the wall. This applies if the terrace is horizontal or the wall vertical. E ac is generally assumed to be zero unless a value of cohesion can be maintained permanently.
E ap acts at the same angle, but keriesl one half the height.
InAlbert Caquot — and Jean Kerisel — developed an advanced theory that modified Muller-Breslau’s equations to account for a non-planar rupture surface.
They used a logarithmic spiral to represent the rupture surface instead.
Lateral earth pressure – Wikipedia
This modification is extremely important for passive earth pressure where there is soil-wall friction. Mayniel and Muller-Breslau’s equations are unconservative in this situation and are dangerous to kefisel.
For the active pressure coefficient, the logarithmic spiral rupture surface provides a negligible difference compared to Muller-Breslau. These equations are too complex to use, so tables or computers are used instead. Terzaghi and Peckindeveloped empirical charts for predicting lateral pressures.
Only the soil’s classification and backfill slope angle are necessary to use the charts. For soils with cohesion, Bell developed an analytical solution that uses the square root of kkerisel pressure coefficient to predict the cohesion’s contribution to the overall resulting pressure.
These equations represent the total lateral earth pressure. The first term represents the non-cohesive contribution and the second term the cohesive contribution. The first equation is for the active earth pressure condition and the second for the passive earth pressure condition. From Wikipedia, the free encyclopedia.
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