Difference between types of embedded beam row

Question

Hi 
 
 I have reviewed the reference manual trying to identify the differences between the 3 types of embedded beam row provided in plaxis (rock bolt, pile and grout body). From a software behaviour point of view, what is the difference between these types? Can I use them interchangeably? I am asking this to explore using an anchor and grout body to simulate pretensioning a rock bolt (for which i couldn't find an easy way to do in plaxis). 
 
 Thank you for your help!

Faseel Khan · Accepted Answer

Embedded beams can be used to model different types of slender structures that interact with the surrounding soil/rocks such as piles, ground anchors or rock bolts. A data set for embedded beams generally represents a certain type of embedded beam, including the pile/rock bolt material and geometric properties, as well as the interaction properties with the surrounding soil or rock (bearing capacity). 
 
 For rock bolts, the bearing capacity may be defined in a similar way to piles, although rock bolts generally do not have an end bearing. 
 Depending on the Embedded beam behaviour for Pile and Rock bolts, the connection point may be indicated as: Top/Bottom in case of piles or First/Second in case of rock bolts. 
 
 You can use these interchangeably if you know how to properly define the connection point and what their definitions are.

Faseel Khan · Answer

An embedded beam is a structural object (such as a pile, rock bolt or grout body) composed of beam elements that can be placed in arbitrary direction in the sub-soil and that interacts with the sub-soil by means of special interface elements. The interaction may involve a skin resistance as well as a foot resistance. The skin friction and the tip force are determined by the relative displacement between the soil and the pile. Although an embedded beam does not occupy volume, a particular volume around the pile (elastic zone) is assumed in which plastic soil behaviour is excluded. The size of this zone is based on the (equivalent) pile diameter according to the corresponding embedded beam material data set. This makes the pile behave almost like a volume pile. However, installation effects of piles are not taken into account and the pile-soil interaction is modelled at the centre rather than at the circumference. Note: The embedded beams are suitable for pile types that cause a limited disturbance of the surrounding soil during installation. This may include some types of bored piles (e.g. displacement screw piles), but not most of the technologies for replacement piles or displacement piles. The installation effect has a significant influence on the soil stress ratio (K0 ) and the pile skin resistance (Tskin). In such a case, it's necessary to properly evaluate these factors in order to simulate the pile installation effect. 
 Special feature of this structural element is that it is not directly coupled to the mesh. It is indirectly coupled via a line to line interface (consisting of spring elements and sliders). The principle is shown in the figure below. Note that as a result of this implementation the mesh is continuous so soil can &ldquo;flow through&rdquo; the embedded pile row. 
 Note that the axial springs also have sliders to be able to represent a maximum shaft and base force (which is a user input). 
 The embedded piles in 2D basically behave in the same manner as the 3D embedded piles: a structural line element coupled via springs and sliders to the mesh. The biggest difference, which also accounts for the 2D vs. 3D behaviour, is the stiffness of the line to line interface. The stiffness of the springs in the 3D line to line interface is set to a high value such that elastic deformations are negligible but not so stiff that numerical problems arise. As a result of this 3 choice all deformations of the pile are a result of elastic/plastic deformations of the soil itself and/or from plastic deformations in the line to line interface. 
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Difference between types of embedded beam row

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