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Specifications and Procedures

《Technical specification for building foundation pit support》JGJ 120-2012

Internal force calculation method

Incremental method

Support structure safety level

Level 1

Supporting Structure

Importance Coefficientγ0

1.00

Foundation pit depth(m)

14.630

Embedded depth (m)

4.370

Pile top elevation (m)

-1.000

Pile Material Type

Steel sheet Pile

├Cross-sectional area per linear meter A(cm2)

236.00

├Moment of inertia per linear meter I(cm4)

39600.00

└Flexural modulus per linear meter W(cm3)

2200.00

└Bending resistance f(MPa)

215

With or without crown beam

No

waterproof curtain

No

Grading series

1

Number of overloads

1

Horizontal concentrated force on support structure

0

Slope number

Table width (m)

Slope height (m)

Slope factor

1

0.500

1.000

1.000

Overload serial number

Type

Overload value

(kPa,kN/m)

Depth of action

(m)

Action width

(m)

Distance from pit

(m)

Form

Length

(m)

1

15.000

---

---

---

---

---

Soil layers

6

Reinforced soil in pit

No

Final inner dewatering depth

15.130

outside water depth (m)

0.000

Whether the inner water level changes with the excavation process

Yes

The distance between the inner

water level and the excavation surface (m)

1.000

Elasticity calculation method specified by soil layer

ㄨ

Elastic calculation method

m

Calculation method of earth pressure outside pit during internal force

calculation

initiative

layer number

Soil name

Layer thickness

(m)

Weig ht

(kN/m

3)

Float weight

(kN/m3)

Cohesion

(kPa)

Internal friction angle (degree)

Cohesion

underwater (kPa)

Internal friction angle underwater

(degree)

1

miscellaneous fill

4.30

18.0

8.0

6.00

8.00

6.00

8.00

2

fine sand

4.50

19.0

9.0

0.00

25.00

0.00

25.00

3

clay soil

0.90

20.9

10.9

7.50

20.20

7.50

20.20

4

clay soil

4.80

21.0

11.0

12.40

25.35

12.40

25.35

5

clay soil

3.90

25.0

15.0

11.70

25.46

11.70

25.46

6

medium

weathered rock

100.00

20.0

10.0

---

---

15.00

30.00

layer number

Frictional resistance with anchor (kPa)

Soil and water

calculation method

m,c,K value

Standard value of ultimate bearing capacity (kPa)

1

60.0

combine

m method

1.08

120.00

2

60.0

separate

m method

10.00

120.00

3

60.0

combine

m method

6.89

120.00

4

120.0

combine

m method

11.56

120.00

5

120.0

combine

m method

11.59

120.00

6

120.0

combine

m method

4.00

120.00

layer number

Effective internal friction angle φ'(degree)

Estimation formula of static earth pressure coefficient

static earth pressure coefficient Ko

1

---

---

---

2

---

---

---

3

---

---

---

4

---

---

---

5

---

---

---

6

---

---

---

anchor channels

6

reaming bolt

ㄨ

Anchor

No

Anchor type

horizontal spacing (m)

vertical spacing (m)

Incidence angle

(°)

Total length

(m)

Anchoring section length (m)

1

inner support

1.000

1.500

---

---

---

2

inner support

1.000

2.700

---

---

---

3

inner support

1.000

2.950

---

---

---

4

inner support

1.000

3.300

---

---

---

5

inner support

1.000

1.000

---

---

---

6

inner support

1.000

2.480

---

---

---

Anchor No

Pre Pressure (kN)

Anchor stiffness (MN/m)

Anchor diameter (mm)

Work condition No

Fixed anchor

Adjustment coefficient

Material resistance (kN)

Material resistance

Adjustment coefficient

1

0.00

9754.71

---

2～

---

3000.00

1.00

2

0.00

9754.71

---

4～

---

3000.00

1.00

3

0.00

9754.71

---

6～

---

3000.00

1.00

4

0.00

9754.71

---

8～12

---

3000.00

1.00

5

0.00

7162.46

---

11～

---

3000.00

1.00

6

0.00

2520.00

---

10～

---

3000.00

1.00

Layer No

Soil Name

Water and water

Water pressure

Adjustment coefficient

Outside earth pressure Adjustment

coefficient 1

Outside earth pressure Adjustment

coefficient 2

Inside earth pressure

Adjustment coefficient

Inside earth pressure

value(kPa)

1

miscellane ous fill

combine

---

1.000

1.000

1.000

10000.000

2

Fine sand

separate

1.000

1.000

1.000

1.000

10000.000

3

clay soil

combine

---

1.000

1.000

1.000

10000.000

4

clay soil

combine

---

1.000

1.000

1.000

10000.000

5

clay soil

combine

---

1.000

1.000

1.000

10000.000

6

medium weathered rock

combine

---

1.000

1.000

1.000

10000.000

Working condition

No

Working condition

type

depth

(m)

Anchor

No

1

excavate

2.000

---

2

add support

---

1.inner support

3

excavate

4.700

---

4

add support

---

2. inner support

5

excavate

7.650

---

6

add support

---

3. inner support

7

excavate

10.950

---

8

add support

---

4. inner support

9

excavate

14.630

---

10

add support

---

6. inner support

11

add support

---

5. inner support

12

dismantle

---

4. inner support

Overall stability calculation method

Swedish section law

Stability calculations using stress states

total stress method

Whether to consider internal support in stability calculation

√

Soil strip width in strip method (m)

1.00

Stiffness reduction factor K

0.850

Anti-bump stability considering arc sliding mode

√

Overturning stability by taking moment to support bottom

ㄨ

Overturning stability with the lowest anchor as the axis

√

Moment reduction factor

1.00

Shear reduction factor

1.00

Load Partial Factor

1.25

Part

No

Internal force type

elastic method calculated

classical law

calculated

internal force design

value

internal force

practical value

Maximum bending moment inside the foundation pit (kN.m)

233.53

462.93

291.91

291.91

1

Maximum bending moment outside the foundation pit (kN.m)

213.27

465.51

266.59

266.59

Maximum shear force (kN)

267.85

254.29

334.81

334.81