verification of gravity wall

7/28/2019 Verification of Gravity Wall

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www.finesoftware.eu GEO5 - Engineering manual1

Engineering manuals for GEO5 programs

Verification of gravity wall

Assignment ................................................................................ 2Solution ...................................................................................... 3Basic input: Stage 1 ..................................................................... 3Analysis results: Stage 1 ............................................................. 8Basic input: Stage 2 .................................................................... 9Analysis results: Stage 2 ........................................................... 10Conclusion ............................................................................... 10


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Verification of gravity wall

In this chapter an analysis of an existing gravity wall for permanent and accidental design situations is

performed. Construction stages are also explained.

Assignment

Using EN 1997-1 (EC 7-1, DA2) standard, analyze an existing gravity wall for stability, overturning, and

slip .

Road traffic acts on the wall with magnitude of 10 kPa. Check the possibility to install the barrier on

the top of the wall. An accidental load from a car crash is considered as 50 kN/m and it acts

horizontally at 1,0 m. Dimensions and shape of the concrete wall can be seen in the picture below.

Inclination of the terrain behind the construction is 10 , the foundation soil consists of silty

sand. The friction angle between the soil and wall is 18 .

Determination of bearing capacity and dimensioning of the wall is not part of this task. In this

analysis, consider effective parameters of soil.

Scheme of the gravity wall - assignment


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In the next step, input the material of the wall and geological profile. Unit weight of wall is

324 mkN . Wall is made from concrete C 12/15 and steel B500. Then define parameters of soil

and assign them to the profile.

Table with the soil parameters

Soil

(Soil classification)

Unit weight

3mkN

Angle of

internal friction

ef

Cohesion

of soil

kPacef

Angle of friction

structure soil

MS Sandy silt,

firm consistency18,0 26,5 12,0 18,0

Dialog window Add new soils

Note: The magnitude of active pressure depends also on friction between the structure and soil in the

angle ef 32

31 . In this case we consider the influence of friction between the structure

and soil with value of ef32 (d =18), when analyzing earth pressure. (More info in HELP F1).


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In the frame Terrain select the shape of terrain behind the wal l. Define its parameters, in

terms of embankment length and slope angle as shown below.

Frame Terrain

In the next frame, define Surcharge. Input the surcharge from road traffic as Strip, with

its location on terrain, and as a type of action select Variable.

Dialog window Edit surcharge


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In the frame FF resistance choose the shape ofthe terrain in front of the wall and define

the other parameters of front face resistance.

Frame Front face resistance

Note: In this case, we do not consider resistance on the front face, so the results will be conservative.

The FF resistance depends on the quality of soil and allowable displacement of the structure. We

consider pressure at rest for the original soil or well compacted soil. It is possible to consider passive

pressure only if displacement of structure is allowed. (More info in HELP F1).

In the frame Stage settings select the type of design situation. In the first construction

stage, consider the permanentdesign situation.

Frame Stage settings


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Now open up the frame Verification, where we analyse the gravity wall for overturning

and slip.

Frame Verification stage 1

Note: The button In detail in the right section of the screen opens a dialog window with detailed

information about the results of the analysis.

Dialog window Verification (in detail)


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Note: For analyses based on EN-1997, the program determins if the force acts favorably or

unfavorably. Next each force is multiplied by the corresponding partial factor which is them on the

report.

Then, open up the frame Stability and analyze the overall stability of the wall. In our case,

we will use the method Bishop, which results in conservative results. Perform an analysis

with optimization of circular slip surface and then validate everything by clicking OK.

Results or pictures will be shown in the report of analysis in the program Gravity wall.

Program Slope stability stage 1

Analysis results: Stage 1

When analyzing bearing capacity, we are looking for values of overturning and slip of the wall

on the footing bottom. Then we need to know its overall stability. In our case, the utilization of the

wall is:

Overturning: 70,0 % 73,26391,376 klvzd MM [kNm/m] SATISFACTORY.

Slip: 90,6 % 17,13853,152 posvzd HH [kN/m] SATISFACTORY.

Overall stability: 72,3 % MethodBishop (optimization) SATISFACTORY.


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Basic input: Stage 2

Now, add construction stage 2 using tool bar in the upper left corner of the screen.

Toolbar Stage of construction

In this stage, define the load from the impact of the vehicle to the barrier, using the frame

Inputforces. The load ais accidental and considers the impact of a vehicle with a weight of 5 tons.

Dialog window Edit force construction stage 2 (accidental design situation)

Then open the frame Stage settings change the design situation on accidental.

Frame Stage settings

The data in the other frames that we entered in stage 1 has not changed, so we dont have to

open these frames again. Select the frame Verification to perform the verification on overturning

and slip again.


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verification of gravity wall

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