Table 4 The parameters in Eq. (16) for friction angle estimation.

From: Estimation of rocks’ failure parameters from drilling data by using artificial neural network

i

W11

W12

W13

W14

W15

W2

b1

b2

1

− 2.7268

3.1729

− 1.8966

1.4533

− 3.3696

3.9083

− 2.3290

0.4914

2

1.0234

− 2.7712

− 1.1594

− 1.5927

− 6.9518

2.7626

1.2426

 

3

− 2.2030

2.1522

2.7034

1.0662

2.2571

− 2.5175

− 0.9233

 

4

8.4448

1.6358

− 2.4581

1.7105

0.7717

− 4.7423

− 4.0064

 

5

1.0771

− 3.1006

− 3.4333

− 1.6010

0.5316

− 4.9676

− 3.3831

 

6

3.6045

0.0828

1.0656

− 1.0406

− 3.1155

− 4.1456

− 1.5837

 

7

− 5.4181

− 0.1021

− 0.5423

3.7557

0.5413

− 2.7456

− 2.2564

 

8

1.5684

− 1.1616

− 0.7748

− 2.0457

− 5.4494

3.6664

− 2.7260

 

9

1.5636

1.0480

− 1.6678

4.2732

− 2.0324

− 4.0835

− 2.1537

 

10

3.0395

4.6627

− 3.1102

4.1239

− 5.3634

2.2452

1.0630

 

11

2.2964

− 0.1194

− 2.2336

− 3.7195

2.9661

2.0912

0.7943

 

12

− 6.5031

4.1496

3.1487

− 2.9225

− 1.2062

− 4.2507

0.6373

 

13

4.2289

0.3285

1.0464

1.1993

3.0443

− 5.5712

0.6665

 

14

3.1476

4.5677

− 2.6159

− 0.3767

− 1.5617

− 5.5610

1.6434

 

15

− 0.1853

0.7083

− 4.8352

1.5455

1.0554

4.1587

0.6326

 

16

− 0.7986

2.9249

2.1390

3.0546

5.8311

2.4651

1.0338

 

17

5.8532

− 5.0631

3.9285

− 4.6260

3.0886

1.7535

0.8709

 

18

0.6294

− 1.4129

− 1.0115

− 3.3946

− 6.3743

− 2.3799

− 5.0854

 

19

− 1.5265

4.3705

3.5004

− 3.9963

0.0326

3.8307

− 0.2961

 

20

3.7355

− 0.2991

7.5053

− 4.3698

2.8003

1.9072

0.9474

 

21

− 0.4720

2.8605

− 3.0669

− 2.9864

2.0164

2.6845

− 4.4890

 

22

4.3245

0.2441

1.9603

0.6809

5.7271

2.3403

1.0564

 

23

1.6552

2.0243

5.1369

1.0186

− 3.4166

3.0640

− 3.1808

 

24

− 2.4345

− 4.7504

4.2931

− 2.7364

− 2.0916

3.0464

1.3291

 

25

− 1.0378

− 2.5454

− 4.5141

3.6022

0.2019

− 2.9869

3.2390

 

26

1.7275

− 2.8544

− 4.8205

− 5.3222

− 1.2669

1.6206

− 5.9244

 

27

− 0.7008

− 1.0796

2.7139

1.3403

2.5573

2.7815

1.3251

 

28

− 6.1850

2.4880

0.9860

− 1.2513

1.5460

− 5.0449

1.5920

 

29

− 5.0047

3.5075

− 0.0028

− 1.9242

− 0.4709

− 5.0888

− 4.7672

 

30

− 1.8034

− 0.2083

− 3.6769

3.5196

− 1.8058

5.8040

− 0.3378

 

31

− 0.7123

− 4.0905

0.7652

− 4.1395

3.3275

3.2667

− 1.2940

 

32

− 6.2928

− 1.2435

1.9389

− 3.3260

− 4.8744

− 2.3704

0.0551

 

33

1.2263

− 3.4571

− 1.3846

− 2.4011

− 2.1300

− 3.4178

2.8852

 

34

3.0520

6.3290

− 2.7741

3.4476

2.1349

2.2798

− 2.3840

 

35

0.9507

2.6073

6.5060

2.2539

− 2.8463

2.5637

1.8638

 
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