PSI - Issue 70

Ashutosh Kumar et al. / Procedia Structural Integrity 70 (2025) 175–182

180

dense soil (RD = 75%), which are 149.14 and 187.29, respectively. Similar trends were observed for the “F q ” at H/B =2 and 3. The “F q ” obtained for H/B of 1,2, and 3 are presented in Table 3 to 5.

100

30

12

90

25

10

80

70

20

8

60

Single Layer, RD=75% Dense Layer over Loose Layer Loose Layer over Dense Layer Single Layer, RD=30%

Single Layer, RD=75% Loose Layer over Dense Layer Dense Layer over Loose Layer Single Layer, RD=30%

15

50

6

40

Uplift Stress, (kPa)

Uplift Stress, (kPa)

Uplift Stress, (kPa)

Single Layer, RD=75% Loose Layer over Dense Layer Dense Layer over Loose Layer Single Layer, RD=30%

10

4

30

20

5

2

10

0

0

0

0

2

4

6

8

10

0

1

2

3

4

5

6

7

8

9

10

0

2

4

6

8

10

12

14

16

18

20

Anchor Displacement, (d/B)%

Anchor Displacement, (d/B)%

Anchor Displacement, (d/B)%

Fig. 4 Uplift stress-anchor displacement response at H/B =1

Fig. 5 Uplift stress-anchor displacement response at H/B =2

Fig. 6 Uplift stress-anchor displacement response at H/B =3

Table 3 Summary of the output obtained from the numerical investigation for H/B=1

Parameters

Single layer, RD = 30% (Loose Layer)

Dense layer over Loose Layer

Loose layer over Dense layer

Single Layer, RD = 75% (Dense Layer)

Uplift Stress (kPa)

7.55

8.64

9.75

10.24

Peak Displacement, d/B (%) Uplift Capacity Factor (F q )

2

2

2

2

149.14

164.10

185.19

187.29

Table 4 Summary of the output obtained from the numerical investigation for H/B=2

Single layer, RD = 30% (Loose Layer)

Dense layer over Loose Layer

Loose layer over Dense layer

Single Layer, RD = 75% (Dense Layer)

Parameters

Uplift Stress (kPa)

19.89

21.98

25.12

27.54

Peak Displacement, d/B (%) Uplift Capacity Factor (F q )

3

3

3

3

196.44

208.74

238.56

251.85

Table 5 Summary of the output obtained from the numerical investigation for H/B=3

Parameters

Single layer, RD = 30% (Loose Layer)

Dense layer over Loose Layer

Loose layer over Dense layer

Single Layer, RD = 75% (Dense Layer)

Uplift Stress (kPa)

47.58

55.10

65.07

27.54

Peak Displacement, d/B (%) Uplift Capacity Factor (F q )

6

6

6

6

313.28

348.84

411.97

497.30

For better understanding of the soil deformation and the failure mechanism in single and two layered soil configurations, the contour displacement plots at H/B of 2, obtained from the PLAXIS 3D has been depicted in Fig. 7. It can be observed that the displacement contour shows a nearly conical failure zone with significant surface displacement, for single layered soil of RD = 30 % (Fig. 7a). In contrast, for single-layered soil with RD of 75%, the failure zone involves a larger volume of soil resisting the uplift force (Fig. 7b). In the two-layered soil configuration of dense sand (RD = 75%) over loose sand (RD = 30%), the contours reflect the dominant influence of the loose layer where the failure surface narrows in the weaker (loose) layer and widens in the upper dense) layer, resulting in reduced anchor performance (Fig. 7c). However, for loose sand over dense sand, the contours indicate the dominant influence of the dense layer (RD = 75%), as most of the soil is participating in resisting the uplift load, leading to improved anchor performance (Fig. 7d).