Tension crack

GEO-SLOPE Internation四年级数学故事 al Ltd, Calgary, Alb饮水机怎么清洗 erta, Canada

Tension Crack

1 Introduction

A tension crack may develop in a slope when the inclination angle of the slip surface is steep and when

the sliding mass is sitting on a weak foundation material. Considering the tension crack will eliminate the

negative normal generated at the ba of a slice, as a result, it gives more reasonable solution, and may

improve convergence in some cas. The purpo of this example is to illustrate the various options in

modeling the prence of a tension crack. Features of this simulation include:

• Analysis method: GLE

• A dry slope

• Entry and exit slip surface option

• Prence of a tension crack

2 Configuration and tup

A simple homogeneous embankment is ud. The slope is assumed to be dry, therefore no pore water

pressure is considered. A Mohr Coulomb soil model is ud. The unit weight of the material is chon to

be 20 kN /m , the cohesion and frictional angle are assumed to be 15 kPa and 30 respectively. Since all

3o

surfaces are assumed to exit at the toe of the embankment, the exit zone is modeled with a single point.

The geometry and material properties are shown in Figure 1.

24

22

20

E

l

e

v

a

t

i

o

n

(

m

)

18

16

14

12

10

8

6

4

810121416182022242628303234363840

Name: Embankment

Model: MohrCoulomb

Weight: 20 kN/m

Cohesion: 15 kPa

Phi: 30

Distance (m)

Figure 1 Geometry and material properties

SLOPE/W Example File: Tension (pdf) (gsz) Page 1 of 6

GEO-SLOPE International Ltd, Calgary, Alberta, Canada

3 Analysis 1 - No tension crack

Figure 2 shows the factor of safety and the critical slip surface when the embankment is analyzed with no

tension crack. Using the View Slice Info feature in CONTOUR, you will e that normal force of slice # 1

is pointing away (negative) from the ba of the slice (Figure 3). In other words, the ba normal force is

in tension. Although the force polygon is still clo showing the slice is in force equilibrium,

nevertheless, the negative normal is not realistic and should avoided by allowing a tension crack to

develop near the crest of the slope.

Figure 2 Critical slip surface and factor of safety with no tension crack

Figure 3 Free body diagram and force polygon of Slice # 1

SLOPE/W Example File: Tension (pdf) (gsz) Page 2 of 6

GEO-SLOPE International Ltd, Calgary, Alberta, Canada

SLOPE/W provides three options to model the prence of a tension crack. The option家常炒虾仁简单做法 s are:

• 幼儿自主游戏 modeled with a tension crack angle

• modeled with a tension crack line

• modeled automatically bad on the negative ba normal

4 Analysis 2 – Tension crack angle

Figure 4 shows the factor of safety and the critical slip surface when the embankment is analyzed with a

tension crack angle. The tension crack angle is assumed to be at 115

o

. Note that the angle is measured

from the positive x-axis.

Figure 4 Critical slip surface a考试卷子模板 nd factor of safety with a tension crack angle

As depicted in Figure 4, a tension crack has developed near the crest. The slip surface extended up

vertically when the ba angle of the slip surface reaches 115

o

. Figure 5 shows the free body diagram and

the force polygon. Note that the ba normal force is not in tension anymore (pointing towards the slice

ba).

SLOP超萌可爱图片 E/W Example File: Tension (pdf) (gsz) Page 3 of 6

GEO-SLOPE International Ltd, Calgary, Alberta, Canada

Figure 5 Free body diagram and force polygon of Slice # 1

5 Analysis 3 – Tension crack line

Figure 6 shows the factor of safety and the critical slip surface when the embankment is analyzed with a

tension crack line. A tension crack zone of about 0.8 m deep is defined using a tension crack line. With

this option, the slip surface extended up vertically when the slip surface interct the tension crack line.

Figure 7 shows the free body diagram and the force polygon. Note that the ba normal force is in

compression (pointing towards the slice ba).

Figure 6 Critical slip surface and factor of safety with a tension crack angle

SLOPE/W Example File: Tension (pdf) (gsz) Page 4 of 6

GEO-SLOPE International Ltd, Calgary,加杨 Alberta, Canada

Figure 7 Free body diagram and force polygon of Slice # 1

6 Analysis 4 – Auto tension crack

Figure 8 shows the factor of safety and the critical slip surface when the embankment is analyzed with an

auto tension crack option. With this option, you do not need to specify a tension crack angle or a tension

crack line, the slip surface extended up vertically from the ba of the slice whenever the ba of the slice

is giving a negative normal force. After the slip surface is modified, the analysis is repeated to ensure that

there is no more negative ba normal. Figure 9 shows the free body diagram and the force polygon.

Note that the ba normal force is not in tension (pointing towards the slice ba).

Figure 8 Critical slip surface and factor of safety with a tension crack angle

SLOPE/W Example File: Tension (pdf) (gsz) Page 5 of 6

GEO-SLOPE International Ltd, Calgary, Alberta, Canada

Figure 9 Free body diagram and force polygon of Slice # 1

7 Closing

It is a good practice to always examine the free body diagram and force polygon of the slices near the

crest of the slope. When the发声 ba normal force is in tension (pointing away from the slice ba), unless

you are modeling a rock in which some tension may be possible, you may want to control the negative

normal with a tension crack. The Auto tension crack option is convenient, in the n that you do not

need to specify a tension crack angle or the position of a tension crack line, however, it is much more

computationally inten due to the iterative procedure.

SLOPE/W Example File: Tension (pdf) (gsz) Page 6 of 6