Lateral earth pressures are derived from the summation of all individual pressure areas behind the retaining wall. Pdf rankines earth pressure theory for nonlinear failure. Beside the rankines theory, there are some other theoretical methods that have been developed to determine the lateral earth pressures. In the next sections, we will deal with two active and passive earth pressure theories. Lateral earth pressure is the pressure that soil exerts in the horizontal direction.
Determination of earth pressure distributions for largescale. Rankines theory of earth pressure soil mechanics youtube. Rankines theory of active earth pressure for cohesive. Rankine source method, applied to seakeeping problems perhaps for the first time by yeung 1 to oscillating ship sections, is increasingly used in practical seakeeping analysis. The method of plastic equilibrium as defined by the mohr rupture envelope of figs. Rankine classic earth pressure solution has been expanded to predict the seismic active earth pressure behind rigid walls supporting c.
Dry or moist backfill submerged backfill partly submerged backfill backfill with uniform surcharge backfill with sloping surcharge. Lateral earth pressure for at rest condition if we consider the backfill is homogeneous then v and h both increase linearly with depth z. Rankine s theory of active earth pressure for cohesionless soil part 1 duration. Rankine versus coulomb earth pressures earth retention. Rankine earth pressure theory and coulombs earth pressure theory. With the rankine method however, wall friction is ignored. It is assumed that the failure surface comprises a logarithmic spiral and a tangent surface. The following cases of active earth pressure on cohesionless backfill will now be considered. Favored by the transportation agencies aashto and fhwa. Assume that the soil has a total unit weight of 120 pcf and a friction value of 32 degrees. Rankines theory maximumnormal stress theory, developed in 1857 by william john macquorn rankine, is a stress field solution that predicts active and passive earth pressure. Soil mechanics lateral earth pressure rankine analysis. The primary difference between rankine and coulomb earth pressure theories is that coulombs considers a frictional retaining wall.
These kinds of theories propose a coefficient which is a ratio between horizontal and vertical stress behind retaining walls. Earth pressure method for retaining walls the constructor. These pressure area are triangular in shape with the base of the triangle at the base of the wall for the soil component and pore water component. This is clearly not correctka does properly increase. Lecture 12 earth pressure and sturucture rankine theory. It can be used to estimate forces on buried structures such as retaining walls, basement walls, and foundations. Coulomb and rankine proposed their theories to estimate active and passive lateral earth pressures. Cantilever reinforcement reinforcement counterfort 4. Lateral earth pressure calculation example the earth. Because a certain amount of strain must develop within the. Rankines theory is applicable for the calculation of the earth pressure on a perfectly smooth and vertical wall, but most retaining walls are far from frictionless soil structure interface. There are two commonly accepted methods for calculating simple earth pressure, coulomb. The first methods for determination of earth loads acting on retaining structures. Why would barometric pressure be important when planning to operate the rankine cycler.
A generalized logspiralrankine limit equilibrium model. Passive earth pressure against retaining wall using log. Rankine active pressure coefficient however the active earth pressure condition will be reached only if the wall is allowed to yield sufficiently. The passive earth pressure problem has been widely treated in the text books. Solutions for soil and structural systems using excel vba programs solutions for soil and structural systems using excel vba programs retainwall designing a concrete or masonry retaining wall three dimensional pive earth pressures by log spiral failure mechanisms a m1 for active b m2 surcharge earth pressure lateral on the retainingwallpres xlsretaining wall. Rankine theory does not include wall friction, for sloping backfill, the resultant is parallel to the slope. See aashto standard specifications for highway bridges. Firstly we will learn rankine earth pressure theory the most important and then coulomb earth pressure theory. The effective stress is the intergranular stress calculated by subtracting the pore pressure from the total stress as described in soil mechanics. Conditions in the case of active earth pressure fig. Rankines earth pressure coefficients for inclined ground reconsidered by slip line method. Later it was extended to include cohesive soil by bell in 1915. Wall designs using kacoulomb is an acceptable approach as with the ncma design methodology.
Neither the coulomb nor rankine method explicitly incorporated cohesion as an equation parameter in lateral earth pressure computations. Figure 2 rankine active or passive pressure with inclined backfill. Soil mechanics lateral earth pressures page 5 figure 7. The method is based on a limitequilibrium approach, and utilizes a composite logarithmic spiral failure surface along which the mohrcoulomb failure criterion is enforced. The estimation of active earth pressures acting on the retaining wall is extremely important for geotechnical design, and analytical approaches are imperative for practical use. Studies for rankines active earth pressure equation assumed11 that the direction of active earth pressure is parallel to the backfill ground ag but has not clearly specified the wall friction angle. Horizontal curve setting by rankine s method part 2 duration. Counterfort strectcher headers filled with soil face of wall 5.
Another popular method to estimate the earth pressure is the logarithmicspiral method proposed by terzaghi 1943. In other words, the interface between the soil and the retaining wall is not assumed frictionless as it is in rank. Lateral earth pressures slide 24of 26 rankine state of stress earth pressure theory. Berrak teymur retaining walls are usually built to hold back soil mass 1. For soils with cohesion, bell 1915 developed an analytical solution that uses the square root of the pressure coefficient to predict the cohesions contribution to the overall resulting pressure.
Various earth pressure theories assume that soils are homogeneous, isotropic. Rankines earth pressure coefficients for inclined ground. Rankine method automatically converts to coulomb if a surface angle or wall friction is included. Designers should be aware that the ncma method ignores the effects of the vertical force components due to coulombs inclined lateral earth pressure inclined at delta. Assume that there is a uniform surcharge of 100 psf located along the surface behind the wall. As wall batter increases, the coulomb earth pressure values decreases. Rankine earth pressures foundation engineering engtips. Conduct startup, operation, data gathering and shut down of rankine cycler steam turbine power system. This video focuses on rankine s lateral active and passive earth pressure. Moment equilibrium conditions are employed to calculate the magnitude of passive thrust. National masonry concrete association ncma and described in their design manual for seg.
Earth pressure and retaining wall basics for nongeotechnical engineers richard p. This video focuses on rankines lateral active and passive earth pressure. We focus on explaining what it is, where it comes from, and spend a bit of time explaining the formula. Rankines earth pressure coef cients for inclined ground reconsidered by slip line method. Lateral earth pressures and retaining walls assistant prof. Earth pressure failure surface loose sand active earth pressure lateral earth pressure. Determination of sulphur dioxide by rankine apsiration. In other words, the interface between the soil and the retaining wall is not assumed frictionless as it is in rankine theory. A back analysis of the slippage is another method which can be used to check the strength. Pdf rankines earth pressure coefficients for inclined ground. It assumes that the soil is cohesionless, the wall is frictionless, the soilwall interface is vertical, the failure surface on which the soil moves is planar, and the resultant force is angled parallel to the backfill.
Extended mononobeokabe method for seismic design of. Lecture 12 earth pressure and sturucture rankine theory 1 free download as powerpoint presentation. This paper presents a technique of determining active earth pressure for a nonlinear failure envelope obtained from a series of direct shear. Soil mechanics theory, and in particular coulombs retaining wall theory, has been. Estimation of the active earth pressure with inclined cohesive.
The coefficient of lateral earth pressure, k, is defined as the ratio of the horizontal effective stress. Nonetheless, the coulomb and rankine methods provide simple and reasonably accurate means for estimating earth loads. The rankine lecture is widely viewed as the most prestigious of the invited lectures in geotechnics. Due to the stress redistribution caused by soil arching phenomenon verified by many models and centrifuge tests, the classic coulomb and rankine active earth pressure. It commemorates william john macquorn rankine, professor of civil engineering at glasgow university, who was one of the first engineers in the uk to make a significant contribution to soil mechanics. Exponent corresponding to soil type for pressure p sinkage. Use the rankine method to calculate the total active lateral force and location of the forces behind a 10foot high vertical wall. It has been used in winemaking for millennia, and is effective due to its multi functional nature. In this video i have talked about the rankines theory of earth pressure to find out the earth pressure in active and passive states. Foundations and earth structures, navfac, design manual 7. Retaining and sheetpile walls, both braced and unbraced excavations, grain in silo walls and bins, and earth or rock contacting tunnel walls and other underground structures require a quantitative estimate of the lateral pressure on a structural member for either a design or stability analysis.
Calculation of passive earth pressure of cohesive soil based on. The rankine method does not take the friction between wall and soil into account. The amount of outward displacement of the wall necessary is about 0. Explore vip membership cantilever walls when designing sheet retaining walls it is normal to assume that the effective lateral stresses acting on the wall are given by simple rankine active and passive zones. Rsskl rankine solution for seismic earth pressures on lshaped retaining walls panos kloukinas 1, george mylonakis 2 abstract an exact limitstress solution is presented for the problem.
Foundation engineering lateral earth pressure lateral earth pressuretheories two theories are used to calculate lateral earth pressure active and passive. A method of slices for estimating seismic earth pressures due to earthquakeinduced pseudostatic body forces is presented herein. Pdf rankine source method for seakeeping predictions. Rankine earth pressure theory states that a soil mass must strain some finite. Lateral earth pressure model is belonging to the first group of theories in classical soil mechanics. The backfill soil is isotropic, homogeneous and is cohesionless. Coulombrankine earth pressure keystone retaining walls. The methods suggested by them are based on theory of classical earth pressure. The rankine active and passive earth pressure coefficient for the specific condition of a. On occasion one may use the finiteelement of the elastic continuum method but this has several distinct disadvantages for.
This was postulated by pauker a military engineer in 1850 and then modified by bell in 1915. Coulomb theory considers wall friction and angle of slope, both are included in the equations for earth pressure constant k, the resultant force is making an angle, equal to the friction of the wall, from the plane normal to wall. As originally proposed, rankines theory is applied to uniform cohesionless soil only. A modified logarithmic spiral method for determining. Simplified method for calculating the active earth. There are other theoretical methods to determine the lateral earth pressures when the wall is vertical, in addition to the method of rankine. When distance d is far enough, the direction of active earth pressure will be constant and is parallel to backfill ground line which is equal to the original rankines assumption. One should not use the rankine method for kp when beta 0, since an inspection of table 114 shows that it decreases with increasing beta.
The rankine method of lateral earth pressure calculation this equation, which derived by william rankine, is the development of coulomb formula. Analysis of experimental results using taguchi methods 117. What will be your reliable source for accurate barometric pressure readings. Weber course content content section 1 retaining walls are structures that support backfill and allow for a change of grade. The proposed formulation is based on rankines conjugate stress concept, without employing any additional assumptions. Rankine active lateral earth pressure this theory is based mainly on the assumption of neglecting friction between the soil and the wall, so no shear forces are developed on soil particles. In soil mechanics, what is the essential difference. For instance a retaining wall can be used to retain fill along a. Rankines lateral earth pressure active and passive. Rankines assumptions for earth pressure theory for active.
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