equivalent fluid pressure retaining wall design
Additionally the feature now allows the user to select a triangular or trapezoidal pressure distribution to model cantilevered retaining walls and restrained basement retaining walls for any height. Equivalent fluid pressure is a simplification of backfill earth pressure against retaining structures.
Geotechnical Engineering Retaining Wall Saturated Soil Hydrostatic Pressure Engineering Stack Exchange
Equivalent fluid pressure is a simplification of backfill earth pressure against retaining structures.
. 4-foot 12 m high gravity retaining wall equivalent fluid pressure of soil 30 pcf 47 kNm³ soil weight 100 pcf 157 kNm³ soil friction coefficient 055 soil bearing capacity 2000 lbft² 0096 MPa 100 solid concrete masonry units 120. The presence of water is also discussed in ASCE 7-10 321. 𝐸 𝑖 J 4 𝛾 𝑃 𝑠𝑒𝑖𝑠 à𝑖𝑐 is the seismic increment expressed as equivalent fluid pressure pcf.
For a cantilever retaining wall level drained condition subdrain the equivalent fluid pressure is simply the product of Ka Gamma where Ka is the Active earth pressure coefficient Gamma is the moist unit weight of the backfill. 614 in Soil Pressure Toe 1809 psf OK Soil Pressure Heel 118 psf OK Allowable 2800 psf. 4-foot 12 m high gravity retaining wall equivalent fluid pressure of soil 30 pcf 47 kNm³ soil weight 100 pcf 157 kNm³ soil friction coefficient 055 soil bearing capacity 2000 lbft² 0096 MPa 100 solid concrete masonry units 120.
From ASCE 7-10 Table 32-1 for some common soils and. The following guidelines shall be used when designing a situational Case 2 retaining wall with seismic pressure. Both increase linearly with depth according to the equation.
We recommend a coefficient of friction of 038 and a passive pressure equal to an equivalent fluid weighing 280 pounds per cubic foot starting. Many design codes define minimum equivalent fluid pressures as a means for establishing a simple retaining wall design criteria without site specific analysis. The more restrictive design shall govern.
DESIGN FLUID PRESSURES FOR RETAINING WALLS SUPPORTING RETAINED SOIL THAT IS OTHER THAN LEVEL. Moreover the equivalent fluid refers to a hypothetical fluid having a unit weight that produces pressure against a lateral support of which its value is presumably equal to that the actual soil produces. If the backfill behind a cantilever retaining wall or restrained basement wall is level we can use the equivalent pressure.
It is common to have a high water table. To resist an equivalent fluid pressure of 78 pounds per cubic foot pcf. Wall Stability Ratios Overturning 232 OK Sliding 195 OK Total Bearing Load 3373 lbsresultant ecc.
The seismic lateral earth pressure for walls retaining level ground can be calculated using the Equation 4 based on Seed and Whitman 19703. USED for Overturning Resistance. 36 4000 lbft² 191520kPa.
Pressure cells were used to measure the lateral earth pressure acting. 11 The objective of the study was to verify or modify existing lateral earth pressure design criteria through the use of long term field measurements of lateral earth pressures on full scale retaining walls. As mentioned in my prior posting the only reason to use the term equivalent fluid pressure is that from measurements we have found that to a first order approximation the lateral earth pressures exerted on a retaining wall without a surcharge loading will increase linearly with depth in the same manner as would occur in a fluid and hence we can specify a.
This water content will also determine the pressure against which a retaining wall must. Together we have created a new support feature that allows the user to define a retaining wall using Equivalent Fluid Pressure EFP given in pounds per cubic foot pcf. For passive pressure 2200 in Equivalent Fluid Pressure Method.
G Equivalent Fluid Density 624 pcf for water. Experienced by the vertical wall on which the pressure is acting as shown in Figure 2 Page 4. 𝛾 𝑃 𝑠𝑒𝑖𝑠𝑖𝑐 3 4 Gℎ 𝑠𝑜𝑖.
27 2500 lbft² 119700kPa. Retaining wall design of equivalent height using only active pressure from Table of Equivalent Fluid Weights ForActive And At-Rest Pressure Based on Expansive SoilConditionsee above. Water pressure can be greatly reduced by providing drainage aggregate and drain pipe directly behind the wall.
Many design codes define minimum equivalent fluid pressures as a means for establishing a simple retaining wall design criteria without site. What the pore-size does do is potentially control other aspects of design- namely whether the design should consider drained or undrained conditions. Equivalent fluid pressure EFP is a simplification of the lateral loading that the soil exerts on an earth-retaining wall.
For a cantilever retaining wall level drained condition subdrain the equivalent fluid pressure is simply the product of Ka Gamma where Ka is the. If simple cantilever walls are being considered the passive resisting pressure on the level ground at the base of slope can be taken to be 280 pcf equivalent fluid pressure from ground surface to 5 feet and 350 psf equivalent fluid pressure at depths greater than. The benefit of equivalent fluid pressure analysis is that it typically creates a easily understood design loading regardless of structure geometry and soil design properties.
If the backfill behind a cantilever retaining wall or restrained basement wall is level we can use the equivalent pressure. ASCE 7-05 32 treats both lateral soil loads and hydrostatic pressure similarly. For example a heavily battered retaining wall design 10 utilizing high assumed soil strengths ϕ 36 may result in very low calculated earth.
Use the soil classification chart above to identify the basic properties of the soil at the site. In this course we will use the word wall to mean the vertical plane on which the earth pressure is acting. 123003 7 2003KeystoneRetainingWallSystems EquivalentFluidPressure Itiscommonforstructuralandgeotechnicalengineerstodefinetheactiveearthpressureloading.
Walls which retain drained earth and come within the limits of the exception above may be designed for an assumed earth pressure equivalent to that exerted by a fluid weighing not less than shown in. These soil properties are approximate. It can be combined with the unit weight of water to determine an equivalent fluid pressure EFP.
For simple retaining wall structures in terms of equivalent fluid pressure such as 40 pcf for ease of calculation. The density of water is much less than most soils 64 pcf however its lateral pressure coeffcient is 10 so the Equivalent Fluid or Lateral pressure is 645 psfft which is higher than most soils in an active pressure case. 32 3500 lbft² 167580kPa.
The wall could be a basement wall retaining wall earth support system such as sheet piling or soldier pile and lagging etc.
