Plaxis Tutorial 01

Transcript

The Program and its  Applications  Applications by Ari Cohen Background •Developed at the Technical University of Delft for Dutch DPWWM •Initially was intended to analyze the soft soil river embankments of the lowlands of olland •!oon after" the company Pla#is $% was formed" and the pro&ram was e#panded to cover a broader ran&e of &eotechnical issues The Netherlands Background •Developed at the Technical University of Delft for Dutch DPWWM •Initially was intended to analyze the soft soil river embankments of the lowlands of olland •!oon after" the company Pla#is $% was formed" and the pro&ram was e#panded to cover a broader ran&e of &eotechnical issues The Netherlands Getting Started P'()I! is comprised of four interconnected but separate interfaces •Input •*alculations •+utput •*urves Tutorial 1: The Modeling the Settlement of a Circular Footing on Sand 1. Choose new or existing ro!ect ". General Settings #. $lane Strain or %xis&mmetr& ' 1()Node or *)Node +. $lane Strain or %xis&mmetr& +. $lane Strain or %xis&mmetr& Cont. y x (. 1()Node or *)Node (. 1()Node or *)Node Cont. *. ,imensions -. Geometr& Contour . /oads 0 Boundar& Conditions • Prescribed Displacements 1. Special Conditions placed on geometry lines that control the displacement of the lines 2. Drawn over geometry lines 3. Can be altered by double clicking on the geometry line associated with it  • ,i#ities 1. Prescribed displacements eual to !ero 2. Can be of hori!ontal" vertical" or total #hori!ontal $ vertical% 3. &i'ities take priority over displacements and other loads • !tandard ,i#ities 1. Convenient and fast input option for many applications • Tractions 1. Distributed loads applied to geometry lines 2. (nput values given in the dimensions force per unit area 3. Can be altered by double clicking on the geometry line associated with it  • Point ,orces 1. )re actually line loads in the out*of*plane direction 2. Can have vertical and hori!ontal components • ,i#ed -otations Select Standard fixities utton . /oads 0 Boundar& Conditions cont. Select $rescried dislacement utton . /oads 0 Boundar& Conditions cont. 2. Material $roerties • Database with material data sets 1. Soil properties and material properties of structures are stored within the database as four types of material sets ./ !oils 0 Interfaces 1/ $eams 2/ 3eote#tiles 0   4/ (nchors • Modelin& of !oil $ehavior 1. +here e'ist three types of soil models that P,)-(S supports ./ Mohr5*oulomb model 1/ ardenin&5!oil model 0  2/ !oft5!oil5*reep model 2. /ohr*Coulomb is most often used as good soil data is not always available to the engineer or scientist  3. /odeling with the /ohr*Coulomb default reuires the following five variables to be input ./ 6oun&7s modulus" 89: 1/ Poisson7s ratio" 8n) 2/ cohesion" 8c: 4/ friction an&le" 8f : and ;/ dilatancy an&le" 8y: 2. Material $roerties cont. • (ll clusters and structural elements in a &iven model must be assi&ned a material before a mesh can be &enerated • The followin& soil parameters will be used for the footin& settlement e#ample< Click Materials utton 2. Material $roerties cont. Select 3New4 material 2. Material $roerties cont. T&e 3sand4 and lea5e the other default inuts 2. Material $roerties cont. Select 6nter gi5en 3New4 data material 6nter Select gi5en data 3New4 and material click 7k 2. Material $roerties cont. ,rag 0 ,ro the 3Sand4 material into the cluster 2. Material $roerties cont. 18. Mesh Generation • 3lobal *oarseness  Distinction is made between five level s of global coarseness 0ery coarse" Coarse" /edium" &ine" and 0ery fine. umber of mesh elements generated ranges from about  elements for the coarse setting to about 1 elements for the very fine setting • 3lobal -efinement   )utomatically generates a refined mesh4 one step per selection • 'ocal *oarseness  (n areas where it may not be necessary to have a very refined mesh" the mesh may be made more coarse by ad5usting the 6,ocal element si!e7 factor for a particular geometry point. +his can be accessed by double clicking on any geometry point  • 'ocal -efinement  (nstead of ad5usting the 6,ocal element si!e7 factor" clusters" lines" or  points can be selected and the local refinement option can be used  Select 3Generate mesh4 7nce the mesh window aears select 39date4 18. Mesh Generation cont. 11. nitial Conditions • +nce the &eometry model has been created and the mesh has been &enerated" the =Initial conditions> must be inputted/ There are two different modes within the initial conditions tab< ;ater conditions mode and the Geometr& configuration mode • Water *onditions mode ./ Water Wei&ht< (n pro5ects that involve pore pressures" the input of water weight in necessary to distinguish between effective stresses and pore pressures. P,)-(S default water weight is set to 1k8m 3 1/ Phreatic 'ines< Pore pressures and e'ternal water pressures can be generated on the basis of phreatic lines. 9ith a phreatic line it i s understood that water pressures above the line are !ero and increase linearly with depth below the line. +he phreatic line can be a general or user defined type 2/ 3roundwater ,low< (n addition to generating water pressures using a phreatic line" water pressures can also be generated using groundwater flow calculations. +his reuires the input of groundwater head boundary conditions 4/ Water Pressure 3eneration< )fter a phreatic line or groundwater boundary conditions are specified" the generate water pressures button is selected to complete the water conditions process • 3eometry *onfi&uration mode ./ Deactivatin& 3eometry *omponents< (n pro5ects where embankments and structures are to be constructed the geometry model will have some elements that are initially not active. +hese elements must be deactivated in this mode. :y default P,)-(S activates all elements of the model outlined in the previous geometry setup stage. Clicking on a particular element in this mode determines if it will be on or not  1/ Initial !tress 3eneration 8?@5Procedure:< (nitial stresses in a body are influenced by the weight of the material and the history of its formation. +he stress state is generally characteri!ed by an initial vertical stress" sn"@ which is related by the coefficient of lateral earth pressure ; . ) default value is given based on