Lateral Earth Pressure John Sturman Rutgers University 180
- Slides: 25
Lateral Earth Pressure John Sturman Rutgers University 180: 473
Lateral Earth Pressure. Introduction We calculate vertical effective stress using the effective stress equations and principles we have previously discussed In many cases we need to consider the horizontal (or lateral) pressures that a soil mass places on a wall, a pile, a braced cut or other structure
Coefficient of lateral earth pressure, k We use the term k to refer to the ratio of lateral to vertical earth pressure. K = σhorizontal / σvertical (Do not confuse this k with the term for hydraulic conductivity)
K is a function of several factors, primarily l The ability of the structural member to move toward or away from the soil mass, and l The shear strength properties of the soil
We refer to the three different cases as l Ko for the at-rest condition, where there is no or insufficient movement l Ka for the active case where the structure can move or flex away from the soil mass l Kp for the passive case where the soil moves toward the structure (or vise versa)
At-rest pressure
At-rest lateral earth pressure σv = γz + q σh = ko σv + u where σv = the vertical overburden q = the surcharge pressure ko = the at-rest earth pressure coefficient, and u = the pore water pressure
At-rest lateral earth pressure For most normally consolidated soils: ko = ~ 1 - sinØ For normally consolidated clays: ko = ~ 0. 95 - sinØ For overconsolidated clays: ko (overconsonsol) = ko(norm consol) (OCR) -2
Active Earth Pressure - Rankine
Active Earth Pressure - Rankine Use ka equations in Das Sec. 7. 3 Note that ka is only a function of the friction angle but the lateral earth pressure includes the effect of cohesion on the structure
Passive Earth Pressure - Rankine l Use Relationships in Das 7. 7
Lateral Earth Pressure - Coloumb l Coloumb developed a set of theories for lateral earth pressure that presume a failure surface to then consider wedges l Coloumb also assumed no friction force between the wall and the soil mass behind it
Rankine and Coloumb’s theories are remarkably similar l They result in similar resultant pressures l They have the ability to include inclined backfill l Rankine is simpler and is probably more commonly used for that reason l The same deflections to mobilize the earth forces are used
Stability Analyses on Retaining Walls l Overtuning l Sliding l Bearing Capacity Failure l Deep Shear Failure l Settlement
Check For Overturning
Check For Sliding
If the FS against sliding is too low
Check Against BC Failure
- Rett sturman
- Rett sturman
- Lateral earth pressure formula
- Lateral earth pressure formula
- Soil pressure calculation
- Solve surface area
- Throchlea
- Pressure support vs pressure control
- Continuous bedside pressure mapping
- Intrapulmonary pressure vs intrapleural pressure
- Starling forces
- How to find partial pressure from total pressure
- Tripod position breathing
- How are metamorphic rocks classified
- Sore throat after surgery
- Bernoulli rule of integration
- Oncotic pressure vs hydrostatic
- Hydrostatic pressure vs colloid osmotic pressure
- Oncotic vs osmotic
- Oncotic pressure vs hydrostatic pressure
- Metamorphism
- Adrenaline
- How to find partial pressure
- Pressure support vs pressure control
- Bevel of et tube
- Low atmospheric pressure