Application	PLAXIS Monopile Designer
Version	PLAXIS Monopile Designer CONNECT Edition V20 and later
Date created	03 November 2020
Date modified	03 November 2020
Original author	Vasileios Basas - Bentley Technical Support Group

Introduction

In the rule-based design approach, soil reaction is defined via mathematical functions and can be derived from previous numerical-based calibrations on other projects (Calibration mode in PLAXIS Monopile Designer), or they can be user-defined from standard publications or supplied by a consultant.

In the latter case, the mathematical function itself consists of certain fitting parameters as a function of depth. This information should be specified by the user in the imported file, which has a specific format used to define the parameterised soil reaction curves. The file also includes relevant data for the site-specific soil conditions and the design (calibration) space based on which the soil reaction curves were generated.

The file format for importing user-defined functions is *.dvf (a plain text file with the .dvf extension). Conventional p-y curves, codified in industry standards such as API RP 2A-WSD, can also be considered as a form of a rule-based model. These can also be used in PLAXIS Monopile Designer, importing a different file format (i.e., .spy for sand and .cpy for clay) for input.

General rules

The user may import any other user-defined dvf, cpy, or spy file as long as it complies with the required format. The general rules for all plain text file formats are:

• No particular units are needed for the data, assuming a consistent set of units is used throughout the tool. Information regarding units can be found in the Units and sign convention (see Monopile Designer Reference manual under the Help menu).
• Lines starting with the symbol hash (#) are regarded as comments (and skipped).
• Leading spaces and tabs are ignored.
• Tabular data columns are separated by single tabs (there is no intentional visual alignment of numbers).
• Floating point numbers are written in full-accuracy scientific notation floating point (i.e., ~ 16 digits such as 4.659996895060823E-19). The readers must not rely on this. They must check tab separators rather than field length.
• The files are written in ASCII and must neither contain any Unicode characters nor single-byte characters outside the allowed range (Char(9), Char(10), Char(13), Char(32)-Char(126)).

To ensure version compatibility of PLAXIS Monopile Designer with dvf, cpy and spy files, users must adapt the corresponding # Version number according to the following Table 1:

PLAXIS Monopile Designer	dvf	cpy	spy
PLAXIS MoDeTo V1	1	-	-
PLAXIS Monopile Designer V20	2	1	1
PLAXIS Monopile Designer V21	2	1	1
PLAXIS Monopile Designer V22	3	2	2

Table 1. Version compatibility

Template Files for Clay and Sand units

The following rule-based design models have been published to date:

• Cowden till model (Byrne et al., 2020) for stiff clays.
• Bothkennar clay model (Burd et al., 2020b) for soft clays.
• General Dunkirk Sand Model (Burd et al., 2020a) for medium to dense sands (45% ≤ RD ≤ 90%).

Rule-based models can be used in PLAXIS Monopile Designer by creating and importing .dvf files with coefficient values corresponding to those in the published models.

Steps for creating a new dvf file

1. Start by preparing a new dvf file containing the depth variation functions of the material model (Cowden till/Bothkennar clay/General Dunkirk sand). This is a regular text file with the ‘.dvf’ extension, which can be created in any plain text editor.

2. Create a new plain text file. Save it as ‘rule-based XXX.dvf’, where XXX corresponds to a name that helps you recognise your created model.

3. Add the file header. This lets PLAXIS Monopile Designer identify the contents of the file and the type of soil.

V20/V21	V22
# Depth variation functions flag PLAXIS MODETO DEPTH VARIATION FUNCTIONS # Version number 2 # Parameterisation function type conic # Material type clay # Drainage type undrained	# Depth variation functions flag PLAXIS MONOPILE DESIGNER DEPTH VARIATION FUNCTIONS # Version number 3 # Parameterisation function type conic # Material type clay # Drainage type undrained
# Depth variation functions flag PLAXIS MODETO DEPTH VARIATION FUNCTIONS # Version number 2 # Parameterisation function type conic # Material type sand # Drainage type drained	# Depth variation functions flag PLAXIS MONOPILE DESIGNER DEPTH VARIATION FUNCTIONS # Version number 3 # Parameterisation function type conic # Material type sand # Drainage type drained

Note: in V20/V21 the file header identified the software with its former name (MoDeTo) and had a version number 2, whereas, in V22, the software changed its name to Monopile Designer and now has a version number 3.

4. Specify the single soil layer and its parameters.

V20/V21	V22
# Number of soil layers 1 # SoilLayer ztop(m) zbottom(m) G0(kN/m2) sutop(kN/m2) subottom(kN/m2) gammasubmerged(kN/m3) k0 1 0.0 -50.0 8.0 150000.0 70.0 150.0 1.0	# Number of soil layers 1 # SoilLayer ztop(m) zbottom(m) gammasubmerged(kN/m3) G0(kN/m2) sutop(kN/m2) subottom(kN/m2) K0 1 0.0 -50.0 8.0 150000.0 70.0 150.0 1.0

V20/V21	V22
# Number of soil layers 1 # SoilLayer ztop(m) zbottom(m) G0(kN/m2) ceff(KN/m2) phieff(deg) psi(deg) gammasubmerged(kN/m3) k0 1 0.0 -50.0 191600.0 0.1 39.0 9.0 10.0 1.0	# Number of soil layers 1 # SoilLayer ztop(m) zbottom(m) gammasubmerged(kN/m3) G0(kN/m2) ceff(kN/m2) phieff(deg) psi(deg) K0 1 0.0 -50.0 10.0 191600.0 0.1 39.0 9.0 1.0

Note: The order of material parameters is different between V20/V21 and V22. For example, for both clays and sands, the position of γ_sub is different.

5. Add the geometries delimiting the design space. This corresponds to the calibration space defined in the PISA publications

V20/V21	V22
# Number of Geometry data sets 11 # L(m) h(m) t(m) Dout(m) E(kN/m2) 20 50 0.091 10 2.10E+08 20 150 0.091 10 2.10E+08 20 50 0.125 10 2.10E+08 60 50 0.091 10 2.10E+08 60 150 0.091 10 2.10E+08 10 25 0.045 5 2.10E+08 10 25 0.083 5 2.10E+08 30 25 0.045 5 2.10E+08 30 75 0.045 5 2.10E+08 15 37.5 0.068 7.5 2.10E+08 45 37.5 0.068 7.5 2.10E+08	# Number of Geometry data sets 11 # h(m) L(m) Dout(m) t(m) E(kN/m2) 50 20 10 0.091 2.10E+08 150 20 10 0.091 2.10E+08 50 20 10 0.125 2.10E+08 50 60 10 0.091 2.10E+08 150 60 10 0.091 2.10E+08 25 10 5 0.045 2.10E+08 25 10 5 0.083 2.10E+08 25 30 5 0.045 2.10E+08 75 30 5 0.045 2.10E+08 37.5 15 7.5 0.068 2.10E+08 37.5 45 7.5 0.068 2.10E+08

Note: There is a change of positions for the length, L and height above the seabed, h between V20/V21 and V22.

6. Add the limits of the calibration.

V20/V21/V22

# Max displacement reached at ground level (m) 1.5 # Max rotation reached at ground level (rad) 0.1

7. Add the DVF coefficients for Cowden till.

V20/V21/V22	V20/V21/V22
Cowden till and Bothkennar clay	General Dunkirk Sand Model (GDSM)
# Fitting parameters C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 C26 C27 C28	# Fitting parameters S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 S12 S13 S14 S15 S16 S17 S18 S19 S20 S21 S22 S23 S24

Cowden till	Bothkennar clay	General Dunkirk Sand Model (GDSM)	Example: General Dunkirk Sand Model (GDSM) – RD = 90%
C1: 241.4 C2: 10.6 C3: -1.65 C4: 0.939 C5: -0.03345 C6: 10.7 C7: -7.101 C8: -0.3085 C9: 0.2042 C10: 1.42 C11: -0.09643 C12: 0 C13: 0.2899 C14: -0.04775 C15: 235.7 C16: 2.717 C17: -0.3575 C18: 0.8793 C19: -0.0315 C20: 0.4038 C21: 0.04812 C22: 173.1 C23: 0.2146 C24: -0.00213 C25: 1.079 C26: -0.1087 C27: 0.8192 C28: -0.08588	C1: 173.8 C2: 12.05 C3: -1.547 C4: 0.7204 C5: -0.00268 C6: 7.743 C7: -3.945 C8: -0.08456 C9: 0.2863 C10: 1.698 C11: -0.1576 C12: 0 C13: 0.4862 C14: -0.05674 C15: 291.5 C16: 3.008 C17: -0.2701 C18: 0.3113 C19: 0.04263 C20: 0.5279 C21: 0.06864 C22: 187 C23: 0.3409 C24: -0.01995 C25: 0.699 C26: -0.1155 C27: 0.8756 C28: -0.09195	S1: 146.1-92.11*RD S2: 8.731-0.6982*RD S3: -0.9178 S4: 0.917+0.06193*RD S5: 0.3667+25.89*RD S6: 0.3375-8.900*RD S7: 0.01532 S8: 17 S9: 0 S10: 0.2605 S11: -0.1989+0.2019*RD S12: 0.5150+2.883*RD S13: 0.1695-0.7018*RD S14: 6.505-2.985*RD S15: -0.007969-0.4299*RD S16: 0.09978+0.7974*RD S17: 0.004994-0.07005*RD S18: 0.09952+0.7996*RD S19: 0.03988-0.1606*RD S20: 44.89 S21: 0.3515 S22: 0.300+0.4986*RD S23: 0.09981+0.3710*RD S24: 0.01998-0.09041*RD	S1: 63.201000 S2: 8.1026200 S3: -0.9178000 S4: 0.9727370 S5: 23.6677000 S6: -7.6725000 S7: 0.01532 S8: 17.000000 S9: 0.000000 S10: 0.2605000 S11: -0.0171900 S12: 3.1097000 S13: -0.4621200 S14: 3.8185000 S15: -0.3948790 S16: 0.8174400 S17: -0.0580510 S18: 0.8191600 S19: -0.1046600 S20: 44.89 S21: 0.3515 S22: 0.7487400 S23: 0.4337100 S24: -0.0613890