Project of foundation design

Project of Foundation DesignInstructor: Dr Nguyen Van Chung- In there:Average value of a feature: Mean square deviation: The mean square deviation:When checking to eliminate gross errors

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HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

PROJECT OF FOUNDATION DESIGN

INSTRUCTOR: DR NGUYEN VAN CHUNG

STUDENT ID: 20149103

HKI 2023-2024

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Project of Foundation Design Instructor: Dr Nguyen Van Chung

TABLE CONTENTS

CHAPTER I: SOIL INVESTIGATION 4

1 Soil investigation formular and definition 4

2 Shallow Foundation (DCMN-DC03)

11 3 Deep Foundation (DCMC-DC05) 23

CHAPTER II: DESIGN PAD FOOTING 43

1 Calculation data 43

2 Choose the depth of the foundation 44

3 Determine size of foundation 45

4 Calculation of reinforcement 53

CHAPTER III: STRIP FOUNDATION DESIGN 57

2 Calculation strip foundation 59

3 Check size of foundation 62

4 Check stability condition 63

5 Check the anti-slip forces condition 64

6 Check condition strength 65

7 Check settlement condition 66

Nguyen Trong Nhan - 20149103

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8 Check punching shear 69

9 Internal calculation of the strip foundation 70

10.Calculate the reinforcement 73

11 Calculate the reinforcement in foundation slab 74

CHAPTER IV: PILE FOUNDATION DESIGN 78

2 Calculation pile foundation 84

3 Choose size of foundation 84

4 Determine the load capacity of the pile 86

5 Determine the number of pile and arrangement the pile 92

6 Check the bearing capacity of pile 93

7 Check the load capacity of the pile 94

8 Check the stability and settlement of the pile foundation 95

9 Check the settlement condition of the foundation 97

10 Design pile cap 99

11 Calculation reinforcement for pile cap 100

12 Check the capacity of the pile during transport and

erection

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102

103

REFERENCES

105

CHAPTER I: SOIL INVESTIGATION

1 Soil investigation formular and definition:

1.1 Statistical theory:

- Geological survey records for foundation design with a large number of boreholesand number of soil samples in a large soil layer The problem is these soil layers wehave to choose is the target to represent the background

- Initially, when drilling, sampling was based on the observation of color change, thedegree of grain that we divided each layer of soil

- According to TCVN 9362-2012, it is called a geotechnical layer when the set ofvalues having its mechanical properties must have a sufficiently small coefficient ofvariation Therefore, we must exclude the samples with data disparate with largemean values for a geological unit

- So geological statistics is a very important job in the calculation of the foundation

1.2 Division of geological units

1.2.1 Coefficient of Variation

We rely on coefficient of variation unary division:

- The coefficient of variation v is determined by the formula:

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- In there:

Average value of a feature:

Mean square deviation:

The mean square deviation:

When checking to eliminate gross errors for double criteria such as adhesion

as follows:

With:

is the eigenvalue of eigenvalues in the same soil layer

n: number of test samples of quantity A in the same soil layer

1.3 Rule for the exclusion of raw errors

- In the sample set of a soil layer with coefficient of variation [], the opposite isachieved then we have to exclude data with large or small errors

- In which []: the largest coefficient of variation, look up Table 1 depending on eachtype of feature

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following formula | - A | ≥ Vσ In which deviation is estimated:� cm

number

(V)

Number oftimesdetermine (n)

Valuestandardnumber(V)

Number oftimesdetermine(n)

Valuestandardnumber(V)

1.4 Standard value of soil characteristics

1.4.1 Standard values of single indicators

- Standard values of all single parameters (physical parameters such as humidity, bulkweight volume, plasticity index, viscosity, and mechanical parameters such as total

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strain modulus, compressive strength, …) is the average of the individual test results

Ā after, excluding gross errors

1.4.2 Standard value of dual indicators:

- The standard values of the dual criteria of unit adhesive force (c) and internalfriction angle () are made according to the method of least squares of the linearrelationship of normal stress and stress the extreme contact of the equivalent sheari i

experiments:

- The standard unit adhesive force c and the friction angle in the standard tc tc aredetermined by the following formula:

- If the above formula can be calculated c < 0, then choose c = 0 and recalculatetc tc

according to the formula:

1.5 Calculating soil characteristics

1.5.1 Calculation value of single indicators

- In order to improve the safety for the stability of the load-bearing foundation, somestability calculations of the foundation are carried out with the calculationcharacteristics

- The calculated value of single criteria is determined by the following formula:

In there:

Atc is the standard value of the features under consideration

The factor of safety on soil is determined by the formula:

- The accuracy index is determined by the formula:

In there:

tα is the coefficient that depends on the confidence probability

Dynamic coefficient is determined according to item 1.2.1

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When calculating the background by intensity (TTGH I), α = 0.95

When calculating the background according to strain (TTGH II), α = 0.85

- The minimum number of a certain criterion experiment with each engineeringgeological unit needs to be ensured is 6

- If within the scope of engineering geology unit there are less than 6 samples, thecalculated values of their criteria are calculated according to the method of minimumaverage and average maximum:

- The choice of calculation according to one of the two formulas depends on thecriteria that increase the safety of the works

1.5.2 Calculation value of double indicators

- The calculated value of the double criteria is determined according to the followingformula:

In there:

Atc is the standard value of the features under consideration

- For double criteria such as: stick force c and coefficient of friction tg

We have the formula: = t να

The coefficient of variation is determined according to the following formulas:and

The mean square deviation is determined according to the following formula: When calculating the background by intensity (TTGH I), α = 0.95

When calculating the background according to strain (TTGH II), α = 0.85Note:

To find the standard and calculated values of c and , it is necessary todetermine not less than 6 values of for each value of normal pressure

When finding the calculated value c, uses the total number of experiments to

do n

Degree of freedom

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- The computed features according to TTGH I and TTGH II have values in the range:

- Depending on the specific design case, we take the sign (+) or the sign (-) to ensuremore safety

- When calculating the background according to the intensity and stability, we takethe calculated characteristics according to TTGH I (in the larger range = 0.95)

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- When calculating the background according to the deformation, we take thecalculated characteristics according to TTGH II (in the range less than = 0.85)

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a) Determine the standard value:

Empty factor by load class

σ = 200(kN/m )2

σ = 300(kN/m )2

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The above sample set is selected

No Drillhole Modelnumbe

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(kN/m )2

σ = 200(kN/m )2

σ = 300(kN/m )2

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b) Determine the standard value:

()

No Drillhole numberModel Depth

Empty factor e corresponding to the load class

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number

τ = (kN/m2)

σ = 100(kN/m )2

σ = 200(kN/m )2

σ = 300(kN/m )2

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=> So all of the samples in layer 4 are selected

b) Determine the standard value:

()

c) Determine the value according to limit state I:

With limit state I then the confidence probability Look up the table we get

d) Determine the value according to limit state II:

With the limit state II then the confidence probability Look up the table we get

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Empty factor e corresponding to the load class

Friction angle and stick force

number

τ = (kN/m2)

σ = 100(kN/m )2

σ = 200(kN/m )2

σ = 300(kN/m )2

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- Soil properties: Heavy phase clay, yellow brown - white grey, hard and soft plasticstate

- Depth: 13.0 – 50.0(m)

- Soil properties: Mixed sand, yellow brown - pink brown white grey

3.1 Geological statistics of soil layer 1:

3.1.1 Single target statistics:

Bulk density:

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=> So the sample set is selected

No numberModel Depth Empty factor e corresponding to the load class P ((0-25) (25-50) (50-100) (100-200)

3.1.2 Empty factor by load class e:

3.1.3 Multiple target statistics:

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a) Check statistics:

= > Accepted the sample test.

b) Determine the value according to limit state:

0.01387 =>

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=> So the sample set is not selected

No numberModel Depth (25-50)Empty factor e corresponding to the load class P ((50-100) (100-200) (200-400)

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3.2.3 Mutiple target statistics:

(kN/m )2

=200(kN/m )2

= > Accepted the sample test.

b) Determine the value according to limit state:

0.212 =>

3.3 Geological statistics of soil layer 3a:

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a) Determine the value according to limit state I:

With limit state I then the confidence probability Look up the table we get

-b) Determine the value according to limit state II:

With the limit state II then the confidence probability Look up the table we get

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Linest method

=100(kN/m )2

=200(kN/m )2

3.5 Geological statistics of soil layer 4a:

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→ This is satisfied settlement condition

3.8 Check the anti-slip forces condition:

Slippage force:

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Anti-slip force:

Friction force between the soil and the bottom of the foundation

Active pressure coefficient of layer 3:

Active pressure at depth z:

Passive pressure of the layer 3:

Total active soil pressure:

Total passive soil pressure:

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→ This is satisfied slip condition

3.9 Check punching shear:

We have

The area of an approximate punching surface (rectangular):

Maximum calculation pressure at the foundation:

Minimum calculation pressure at the foundation:

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Figure 2.3: Punching shear cross-section:

4 Calculation of reinforcement:

4.1 Section 1-1:

Figure 2.4: Schematic of reinforcement according to l

The calculation diagram is console beam under trapezoidal load , we convert it toevenly distributed load :

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Moment at the foot of the column :

The area of reinforcement:

Choose with area of a steel bar:

Number of steel bar:

→ Choose 12 steel bars Distance between each bar:

4.2 Section 2-2:

Figure 2.5: Schematic of reinforcement according to b

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Moment at the foot of the column :

The area of reinforcement:

Choose with area of a steel bar:

Number of steel bar:

→ Choose 10 steel bars

Distance between each bar:

→ Choose a= 250 mm

→ Choose short-edge steel L:

Tiêu đề	Project of Foundation Design
Tác giả	Nguyen Trong Nhan
Người hướng dẫn	Dr. Nguyen Van Chung
Trường học	Ho Chi Minh City University of Technology and Education
Chuyên ngành	Foundation Design
Thể loại	Project
Năm xuất bản	2023
Thành phố	Ho Chi Minh City

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