PLAXIS Version 8 Reference manual - IIT Bombay

1 PLAXIS Version 8 Reference manual i TABLE OF CONTENTS 1 2 General Units and sign 2-1 File 2-3 Compressing project Input 2-4 Help 2-5 3 Input The input program .. 3-1 The input 3-4 Reading an existing General 3-11 Points and Hinges and rotation Node-to-node Fixed-end Loads and boundary 3-25 Prescribed Standard Distributed Point Rotation Material 3-30 Modelling of soil Material data sets for soil and Material Parameters of the Mohr-Coulomb Parameters for interface Modelling undrained Material data sets for Material data sets for Material data sets for Assigning data sets to geometry Simulation of Soil Mesh 3-62 Reference manual ii

2 TPLAXIST Version 8 Basic element 3-62 Global 3-63 Global 3-63 Local 3-63 Local 3-64 Advised mesh generation 3-64 Initial 3-64 Water 3-65 Water weight and cavitation 3-66 Phreatic 3-66 Boundary conditions for groundwater flow 3-70 Water pressure 3-72 Steady-state Groundwater flow 3-74 Closed consolidation 3-77 Material properties for unsaturated 3-78 Initial geometry 3-78 De-activating loads and geometry 3-78 Viewing or re-assigning material data 3-79 Initial stress generation (K0 procedure).. 3-79 Starting 3-82 4 4-1 The calculations 4-1 The calculations 4-3 Defining a calculation 4-4 Inserting and deleting calculation 4-4 General calculation 4-5 Phase identification and 4-6 Calculation 4-7 Load stepping 4-9 Automatic step size 4-9 Load advancement ultimate 4-10 Load advancement number of 4-11 Automatic time stepping (consolidation).

3 4-11 Calculation control 4-12 Iterative procedure control 4-14 Loading 4-19 Staged 4-23 Changing geometry 4-23 Activating and deactivating clusters or structural 4-24 Activating or changing 4-25 Applying prescribed 4-27 Reassigning material data 4-28 Applying a volumetric strain in volume 4-29 Pre-stressing of 4-29 Applying contraction of a tunnel 4-30 iii Changing water pressure Plastic Staged construction with Mstage< Unfinished staged construction Load 4-34 Standard load Other multipliers and calculation 4-39 Sensitivity Analysis & Parameter 4-40 Parameter Sensitivity Defining parameter Defining geometric Starting the Sensitivity View Parameter variation Upper & lower Viewing upper and lower Viewing results of Sensitivity Delete Parameter variation Delete Updated mesh 4-47 Previewing a construction 4-49 Selecting points for 4-49 Execution of the calculation 4-50 Starting the calculation Multiple The calculation Aborting a Output during 4-51 Selecting calculation phases for 4-54 Reset staged construction 4-54 Adjustments to input data in between 4-55 Automatic error 4-55 5 Output data post The output 5-1 The output 5-2 Selecting output 5-4 5-5 Deformed Total.

4 Horizontal and vertical Phase Incremental Total Cartesian Incremental Reference manual iv TPLAXIST Version 8 Cartesian strain 5-7 5-8 Effective 5-8 Total 5-9 Cartesian effective 5-9 Cartesian total 5-9 overconsolidation 5-10 Plastic 5-10 Active pore 5-10 Excess pore 5-11 Groundwater 5-11 Flow 5-12 Degree of 5-12 Structures and 5-12 5-12 5-13 5-13 5-14 Viewing output 5-14 Viewing output in a 5-15 Viewing other 5-16 General project 5-16 Load 5-17 Material 5-17 Multipliers and calculation 5-17 Connectivity 5-18 5-18 Overview of plot viewing 5-18 Report 5-19 Exporting 5-20 6 Load-displacement curves and stress 6-1 The curves 6-1 The curves 6-2 Curve 6-3 Multiple curves in one 6-6 Regeneration of 6-6 Formatting 6-7 Curve 6-7 Frame 6-9 Viewing a 6-10 Viewing a 6-10 7 7-1 Index Appendix A - Generation of initial stresses Appendix B - Program and data file structure INTRODUCTION 1-1 1 INTRODUCTION PLAXIS is a special purpose two-dimensional finite element computer program used to perform deformation and stability analyses for various types of geotechnical applications.

5 Real situations may be modelled either by a plane strain or an axisymmetric model. The program uses a convenient graphical user interface that enables users to quickly generate a geometry model and finite element mesh based on a representative vertical cross-section of the situation at hand. Users need to be familiar with the Windows environment. To obtain a quick working knowledge of the main features of PLAXIS , users should work through the example problems contained in the Tutorial manual . The Reference manual is intended for users who wish to obtain more detailed information about the program features. The manual covers topics that are not covered exhaustively in the Tutorial manual .

6 It also contains practical details on how to use PLAXIS for a wide variety of problem types. The user interface consists of four sub-programs (Input, Calculations, Output and Curves). The contents of this Reference manual are arranged according to these four sub-programs and their respective options as listed in the corresponding menus. This manual does not contain detailed information about the constitutive models, the finite element formulations or the non-linear solution algorithms used in the program. For detailed information on these and other related subjects, users are referred to the various papers listed in Chapter 7, the Scientific manual and the Material Models manual .

7 Reference manual 1-2 TPLAXIST Version 8 GENERAL INFORMATION 2-1 2 GENERAL INFORMATION Before describing the specific features in the four parts of the PLAXIS user interface, this first Chapter is devoted to some general information that applies to all parts of the program. UNITS AND SIGN CONVENTIONS Units It is important in any analysis to adopt a consistent system of units. At the start of the input of a geometry, a suitable set of basic units should be selected from a list of standard units. The basic units comprise a unit for length, force and time.

8 These basic units are defined in the General settings window of the Input program. Table gives an overview of all available units, the [default] settings and conversion factors to the default units. All subsequent input data should conform to the selected system of units and the output data should be interpreted in terms of this same system. From the basic set of units the appropriate unit for the input of a particular parameter is generally listed directly behind the edit box or, when using input tables, above the input column. In this way input errors due to wrong units are reduced. In all of the examples given in the PLAXIS manuals, the default units are used.

9 Table Available units and their conversion factor to the default units Length Conversion Force Conversion Time Conversion mm = m N = kN s (sec) = 1/86400 day [m] = 1 m [kN] = 1 kN min = 1/1440 day in (inch) = m MN = 1000 kN hr = 1/24 day ft (feet) = m lb (pound) = kN [day] = 1 day klb (kilopound) = kN For convenience, the units of commonly used quantities in two different sets of units are listed below: Standard Different Basic units: Length metre [m] feet [ft] Force kilonewton [kN] kilo pound [klb] Time day [day] second [sec] Geometry: Coordinates [m] [ft] Displacements [m] [ft] Reference manual Material properties: Young's modulus [kN/m2] = [kPa] [kips] = [klb/sq ft] Cohesion [kN/m2] = [kPa] [kips] Friction angle [deg.]

10 ] [deg.] Dilatancy angle [deg.] [deg.] Unit weight [kN/m3] [klb/cu ft] Permeability [m/day] [ft/sec] Forces & stresses: Point loads [kN] [klb] Line loads [kN/m] [klb/ft] Distributed loads [kPa] [kips] Stresses [kPa] [kips] Units are generally only used as a Reference for the user but, to some extent, changing the basic units in the General settings will automatically convert existing input values to the new units. This applies to parameters in material data sets and other material properties in the Input program. It does not apply to geometry related input values like geometry data, loads, prescribed displacements or phreatic levels or to any value outside the Input program.