Computation of the primary consolidation settlement 360 days after application of the surcharge load requires knowledge of the local degree of consolidation at point P. The first step in this process is the computation of the time factor; i.e., (9.6.16) At a depth of 4.0 m in the clay, z / Hdr = 4.0/8.0 = 0.50.
Full Answer
What is the surcharge for pavements adjacent to basements?
In association with the axle loads or line loads, it is suggested that a surcharge of 5 kN/m 2 is applied as an imposed load to pavements adjacent to basements.
What is the magnitude of surcharge pressure for retaining walls?
The magnitude of the surcharge pressure ( ps) will be given by; Where retaining walls give support to highways it was traditional to check for the effects of HA loading at ground level. HA surcharge load is usually taken to be 10 kN/m 2. According to BD37/01, the surcharge load for 45 units of HB load should be 20 kN/m 2.
What is a soil surcharge?
We will consider a case where a soil mass, which consists of two soil deposits of bulk unit weight γ 1 and γ 2, of thickness H 1 and H 2 respectively, is subjected to a surcharge. Surcharge is the additional load on the soil which may be created due to any overlying structure or any moving object.
What is a surcharge load on a construction site?
This surcharge load, together with the platform fill, exerts pressures on the underlying soft soil and creates development of excess pore water pressures that are slow to dissipate due to the low permeability of these soft soils. Vertical drainage elements, typically in the form of PVDs, to accelerate the rate of consolidation.
How is surcharge load calculated?
A surface load that is started from the edge of the excavation will be considered. In this case α = β/2 H = 0.0 L1 = 0.0 β = Arctan (L2/H) = 90o βr = π/2 Therefore from eq. (1), the pressure at top of the excavation would be equal to the surcharge pressure.
How are settlements calculated?
13:2451:58Mod-01 Lec-11 Shallow Foundation - Settlement Calculation - I - YouTubeYouTubeStart of suggested clipEnd of suggested clipSoil layer NCC is equal to compression. Index. So either we can use this expression to calculate theMoreSoil layer NCC is equal to compression. Index. So either we can use this expression to calculate the consolidation settlement.
How do you calculate immediate settlement?
Determine the point where the settlement is to be computed and divide the base so the point is at the corner or common corner of one or up to 4 contributing rectangles. The zone of influence is either of the following: Depth z = 5B where B is the least total lateral dimension of base.
How can I reduce my consolidation settlement?
Note: the consolidation settlement can be reduced by conducting any of the following: 1. Increase the length of piles (when the length of piles are increased, “H” value in the preceding equation would reduce. “H” is the thickness of the compressible portion of the clay layer).
What is full and final settlement amount?
The full and final settlement consist of clearance of dues towards an employee upon their exit from the company. It includes the salary drawn, leave encashment, reimbursements, variables etc.
What is settlement analysis?
Soils consolidate under the application of loads from buildings. All foundations settle as the soil around and beneath the foundation adjust to the loading. Buildings with light loads or built on rock may experience negligible settlement.
What is allowable settlement?
The allowable settlement is defined as the acceptable amount of settlement of the structure and it usually includes a factor of safety.
How are secondary settlements calculated?
t2 = t100 (f) + Δt = time for which secondary settlement is to be calculated.
How do you calculate elastic settlement?
Elastic settlement calculation using displacement influence factors has the general form (Poulos and Davis, 1974):(1) ρ = q B E s I where ρ is the foundation settlement; q is the applied stress; B means the foundation width; Es stands for the equivalent elastic soil modulus; and I is the displacement influence factor.
How is consolidation settlement calculated?
Degree of Consolidation = Amount of consolidation at a given time with a soil mass / Total amount of Consolidation obtainable under the given stress condition. This also can be written as follows for a clay layer.
How can you avoid foundation settlement?
2:213:46Differential Settlement. - Its Causes and How to Prevent it - YouTubeYouTubeStart of suggested clipEnd of suggested clip1 do proper geotechnical investigation of the soil. To study the surrounding environment 3 the soilMore1 do proper geotechnical investigation of the soil. To study the surrounding environment 3 the soil over which the building is constructed must not be expansive in nature.
How do you calculate the rate of consolidation?
1:593:29Time rate of consolidation: average degree of consolidation explained.YouTubeStart of suggested clipEnd of suggested clipThe amount or the distance that the layer squeezes. At a given time divided by the ultimateMoreThe amount or the distance that the layer squeezes. At a given time divided by the ultimate settlement so what is the proportionality between these two parameters.
How is settlement money divided?
The percentage of the settlement or judgment that attorneys charge does vary slightly, usually between 25% to 50%, depending on the type of case being handled.
How much can I ask for in a settlement agreement?
The rough 'rule of thumb' that we generally use to determine the value of a reasonable settlement agreement (in respect of compensation for termination of employment) is two to three months' gross salary (in addition to your notice pay, holiday pay etc., as outlined above).
How do you ask for more money in a settlement?
Send a Detailed Demand Letter to the Insurance Company Because the insurance company will likely reply with an offer for an amount lower than what you've asked for in the demand letter, you should ask for between 25 and 100 percent more than what you would be willing to settle for.
Should I take a lump sum or structured settlement?
You should take a lump sum settlement for all small settlements and most medium-sized settlements (less than $150,000 or so). But if you are settling a larger case, there are two good reasons for doing a structured settlement. First, the structure guarantees that you won't spend the money too fast.
How much settlement is acceptable for a road embankment?
A fixed-end arch would suffer greatly if the abutments settle or rotate. For road embankments, storage silos and tanks a settlement of 300mm - 600mm may be acceptable, but for machine foundations the settlement may be limited to 5mm 30mm. Different types of construction materials can withstand different degrees of distortion. For example, sheet metal wall panels do not show distress as readily as brick masonry.
What is the value of m in a settlement?
m = number of corners contributing to settlement ΔHi. At the footing center m= 4; and at a corner m = 1, at a side m = 2.
Why is the leaning tower of Pisa undergoing consolidation settlement?
The lean is caused by consolidation settlement being greater on one side. This, however, is an extreme case. The principal settlements for most projects occur in 3 to 10 years.
What is the difference between total settlement and differential settlement?
Total settlement is the magnitude of downward movement. Differential settlement is non-uniform settlement. It is "the difference of settlement between various locations of the structure. Angular distortion between two points under a structure is equal, to the differential settlement between the points divided by the distance between them.
What happens if soil shears fail?
A soil shear failure can result in excessive building distortion and even collapse. Excessive settlements can result in structural damage to a building frame nuisances such as sticking doors and windows, cracks in tile and plaster, and excessive wear or equipment failure from misalignment resulting from foundation settlements.
What happens after primary consolidation?
After primary consolidation the soil structure continues to adjust to the load for some additional time. This settlement is termed secondary consolidation/secondary compression. At the end of secondary consolidation the soil has reached a new K o -state (at-rest state).
What is the final settlement of a foundation?
Generally, the final settlement of a foundation is of interest and U is considered equal to 1 (i.e. 100% consolidation) 1. Immediate Settlement. Immediate settlement takes place as the load is applied or within a time period of about 7 days. Predominates in cohesion less soils and unsaturated clay.
What is the minimum surcharge load for retaining walls?
According to BS 8002, the minimum surcharge load that should be applied to retaining walls is 10 kN/m 2. For shallower retaining walls, the surcharge may be reduced if the designer is confident that a surcharge of 10 kN/m 2 will not occur during the life of the structure.
When to use additional surcharge?
Additional surcharge loading should be used in the design to take account of incidental loading arising from the construction plant, stacking of materials, and movement of traffic both during construction and subsequently unless the nature or layout of the site precludes the need for such additional surcharge. However, as practicable as possible, stockpiling materials close to retaining walls should be avoided.
What are the loads on Earth retaining walls?
Earth retaining structures are subjected to a myriad of loads such as earth pressure, water pressure, and earthquake loads (in seismic zones). However, when loads are applied on the earth retained at the back of the retaining wall, surcharge loads are induced on the retaining structure. The magnitude of lateral pressure transferred to the wall depends on the spatial distribution of the load, its magnitude, and location (distance away from the wall). The aim of this article is to evaluate the common sources of surcharge loads on earth retaining structures.
Can you double the pressure of a rigid wall?
It is recommended that horizontal earth pressures against ‘rigid’ walls determined using Boussinesq’s theory of stresses in an elastic half-space should be doubled for design purposes. Boussinesq’s theory for horizontal pressures assumes horizontal movement. However, with truly rigid walls there is actually no movement. So an identical balancing surcharge on the other side of the wall, i.e. a mirror image surcharge, is required and this in effect doubles the pressure. Doubling pressure is in line with field data by Terzarghi and with French practice.
Abstract
Preloading with surcharge is the most common technique of ground improvement used in highway engineering. An equation describing the relationship between the settlement rate during preloading with surcharge and the post-construction settlement under the conditions of equal loads was derived.
References (0)
Based on hyperbolic fitting method, two equations about the relation between the settlement rate and the residual settlement and relation between the residual settlement and the post-construction settlement were deduced under constant load.
What is a surcharge load on a retaining wall?
Surcharge loads acting on retaining walls are additional vertical loads that used to the backfill soil above the top of the wall. It can be either dead loads, for example, sloping backfill above the wall height or live load, which could result from the highway or parking lot, paving, or adjacent footing.
What is live load surcharge?
Live load surcharge is considered when vehicular actions act on the surface of backfill soil at a distance, which equal or less than the wall height from the wall back face. Active pressure from uniform surcharge is explained in Figure 2.
What is the Rankine method of calculating the pressure of a wall?
The Rankine method of Lateral Earth Pressure Calculation. This equation, which derived by William Rankine, is the development of the coulomb formula. The Rankine method does not take the friction between the wall and soil into account. This makes it a conservative way of designing retaining walls.
What are the loads and forces acting on retaining walls?
There are various types of loads and forces acting on retaining wall, which are: Retaining wall design could include any or all of loads and forces which are explained in the following sections: 1. Lateral Earth Pressure Acting on Retaining Wall.
Which equation is used to calculate lateral earth pressure?
Coulomb and Rankine e quations are two major formulas which are used to compute lateral earth pressure:
What forces are covered in seismic design of retaining wall?
Forces related to earthquake is covered in seismic design of retaining wall.
What is vertical point load?
Point vertical loads on walls are considered to be spread downward in a slope of two vertical to one horizontal. Consequently, there will be rather low compressive stresses at the base of the wall; girder reactions on walls is an example of vertical point load.
Why can we notice in all our calculations for effective stress at different depths?
We can notice in all our calculations for effective stress at different depths because of the surcharge load effective stress increased by the surcharge load q at all the depths.
How to write stress under any material?
So we can directly write the stress under any material as unit weight of the material multiplied by the height of the material above that point.
What is the effect of buoyancy force on soil mass?
But if we put this soil mass in water then because of buoyancy force the net total downward force is reduced consequently the stress on particles is reduced. This reduced stress is called effective stress.
How is stress given as force?
We know that stress at any point or plane under the soil can be given as force on that plane divided by the area of the plane.
Is surcharge given as pressure?
Notice that surcharge load is given as force per unit area, which is equivalent to pressure or stress. So it can be directly used in the equations to provide stress at any depth.
Soil Settlement and Soil Shear
Components of Settlement
- The components of settlement of a foundation are: 1. Immediate settlement 2. Consolidation Settlement, and 3. Secondary compression (creep) ΔH = ΔHi + U ΔHc + ΔHs ΔH = total settlement, ΔHc = consolidation settlement, ΔH = secondary compression, U = average degree of consolidation. Generally, the final settlement of a foundation is of interest and ...
Immediate Settlement Calculations
- Where q0 = intensity of contact pressure in units of Es (Undrained Modulus of Elasticity) B’ = least lateral dimension of contributing base area in units of ΔHi Es, μ = Elastic Soil Parameters. A major problem is of course to obtain correct stress-strain modulus Es. Es can be found from laboratory tests like unconfined compression tests, Triaxial compression tests, and in-situ tests like SPT, C…
Consolidation Settlement Calculations
- After primary consolidation the soil structure continues to adjust to the load for some additional time. This settlement is termed secondary consolidation/secondary compression. At the end of secondary consolidation the soil has reached a new Ko-state (at-rest state). Secondary consolidation may be the larger component if settlement in some soils, particularly in soils with …
Settlement Limits
- Total settlement is the magnitude of downward movement. Differential settlement is non-uniform settlement. It is "the difference of settlement between various locations of the structure. Angular distortion between two points under a structure is equal, to the differential settlement between the points divided by the distance between them. Theoretically, no damage will be done to a structur…