- #HOW TO APPLY BACK PRESSURE PLAXIS 2D MANUAL#
- #HOW TO APPLY BACK PRESSURE PLAXIS 2D PRO#
- #HOW TO APPLY BACK PRESSURE PLAXIS 2D FREE#
This paper summarises the fundamental concepts relating to performance of piles in rock and provides a basis for displacement focused design of piles in rock. Ground investigations should measure rock mass stiffness and defect properties, as well as intact rock strength. Standards, codes of practices, reference books and other sources of design information should focus foundation design in rock on displacement rather than strength performance.
#HOW TO APPLY BACK PRESSURE PLAXIS 2D FREE#
Exceptions occur for footings that are undermined, or where unfavourable structure in the rock allows movement towards a free surface to occur. In addition, poor pile performance is much more likely to result from poor construction practices than excessive displacement of the rock mass. Unsatisfactory performance of a pile in rock is usually a displacement issue and is a function of rock mass stiffness rather than rock mass strength. The load carrying capacity of even low strength rock (in most situations) is far in excess of the strength of the structure (for example, a building column) transmitting the load. Even if it can be reasonably quantified, it has little, if any, significance to the performance of a pile in rock. However, for many of the rock conditions encountered, the bearing capacity of piles is a nebulous concept and a figment of the designer's imagination. This is not the behaviour displayed in PLAXIS 2D 2016.00.Despite significant advancements in in situ test techniques, construction practices, understanding of rock joint and rock mass behaviours, and numerical analysis methods, the design of bored concrete cast-in-situ piles in rock is still largely based on the assessment of bearing capacity. Similarly, in Figure 2 the axial force should be the lowest at the top and gradually increase downwards due to the self weight of the concrete of the side drift. The correct behaviour should display a bending moment at the top and bottom of the line. In Figure 1 the bending moment line generated from the automatic centerline shows no bending moment at the top and bottom of the side drift, which is incorrect as all connections are rigid in this tunnel case.
#HOW TO APPLY BACK PRESSURE PLAXIS 2D MANUAL#
Incorrect normal force values calculated with automatic centerline (left) and correct values with manual centerline (right) Incorrect bending moments calculated with automatic centerline (left) and correct values with manual centerline (right)įigure 2. In 2016.00, the automatic centerline might not detect the structural forces correctly for an internal tunnel lining connected to concrete elements at the end points.įor example, the axial forces and the bending moments might be incorrect, as shown Figure 1 and Figure 2.įigure 1. Pro tip: Temperature vs time shows latent heat plateau For this tutorial, when pre-selecting a node in the middle of the model, the temperature versus time plot shows the phase change plateau displayed below: Due to the latent heat kicking in, we should see the temperature plateau characteristic of ground freezing. When performing a ground freezing analysis, it is good practice to check that the phase transition from liquid water to ice has been properly triggered.
#HOW TO APPLY BACK PRESSURE PLAXIS 2D PRO#
Updated Figure 16.8 for PLAXIS 2D 2016.01 Pro tip Updated Figure 16.7 for PLAXIS 2D 2016.01 Updated Figure 16.6 for PLAXIS 2D 2016.01 They are shown below, and as you can see, they are hardly noticeable. They however bring some slight changes in the results of tutorial 16. Many improvements have been made to the convection-diffusion implementation, in particular in terms of calculation stability and performance. Updated Figure 15.18 for PLAXIS 2D 2016.01 Tutorial 16: Freeze pipes in tunnel construction Updated Figure 15.17 for PLAXIS 2D 2016.01 See section 2.3 of our document on thermal and coupled THM analysis for more details. The thermal expansion of liquid water plays a role in excess pore pressures and groundwater flow, but not directly in the displacements. In 2016.00, the thermal expansion of water was contributing to the thermal strain of the soil body, which is incorrect: the displacements are only governed by the thermal expansion of the soil skeleton. Tutorial 15: Thermal expansion of a navigable lock
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