Retaining Walls Flashcards
Lateral Earth Pressure is a function of what four factors?
- The type and amount of wall movement.
- The shear strength parameters of the soil.
- The unit weight of the soil.
- The drainage conditions in the backfill.
What is active earth pressure?
The wall tilts away from the soil that is retained. With sufficient wall tilt, a triangular soil wedge behind the wall will fail.
What is passive earth pressure?
The wall may be pushed into the soil that is retained. With sufficient wall movement, a soil wedge will fail.
What is Normally Consolidated Soil?
Is soil that has undergone the same amount of consolidation in the past as it is currently experiencing. The current effective stress state of the soil is equal to or less than the maximum stress state that it has experienced in the past.
What is over-consolidated soil?
is soil that has experienced a higher effective stress state in the past than it is currently experiencing. Could be due to erosion of overlying soil layers, natural weathering, or the removal of structures that were previously present. Characterized by a higher strength and stiffness than normally consolidated soil, which means that it is more resistant to deformation.
What is the over-consolidation ratio?
is the measure of the degree to which soil is over-consolidated. Defined as the ratio of the maximum effective stress that the soil experienced in the past to its current effect stress state.
What does a high OCR indicate?
That the soil has a higher strength and stiffness, which means its more resistant to deformation.
What information can the OCR provide an engineer?
A good estimation of whether the soil bearing capacity is adequate for structures relying on soil bearing as support.
What will happen to the pressure diagram if a water table is located below the height of the retaining wall?
The hydrostatic pressure is added to the overall pressure diagram.
How do you find the total force per unit length of the wall?
From the Pressure diagram…Po=A1+A2+A3+A4..etc.
For the retaining wall shown in Figure 12.5a, determine the lateral earth force at rest per unit length of the wall. Also determine the location of the resultant force. Assume OCR=1.
Po=122.85 kN/m
Z=1.53 m
How do you find the location of the center of pressure measured from the bottom of the wall?
Z=(A1((H/2)+A2(H/3))/Po
What does angle alpha, theta, and beta represent when talking about retaining walls?
Alpha is the granular backfill angle with the horizontal. Theta is the back of the retaining wall that is inclined at an angle theta with the vertical. Beta is the angle at which the horizontal pressure will be inclined, with the plane draw at a right angle to the back face of the wall.
What are examples of surcharge loadings on a retaining wall?
Railroads, highways, sign/light structures, buildings, construction equipment, and material stockpiles.
