Determination of forces in geo-reinforcements is performed by splitting and assigning the calculated earth pressure to individual layers. Each reinforcement accommodates part of the active pressure, which acts in the corresponding layer, i.e. force developed in the reinforcement Fx = ΣTa,hor.
Forces transmitted by individual reinforcements
Shape of the slip surface depends on the selected standard of calculation.
Analysis of internal stability varies by type of geo-reinforcements:
- extensible reinforcements (Standard - straight slip surface, AASHTO - Extensible, FHWA NHI-10-024)
- inextensible reinforcements (AASHTO - Inextensible, JTGD30 - 2004 Highway China Code, TB 10025 Railway China Code, BS 8006 - Coherent Gravity Method)
Earth pressure is considered active for extensible reinforcements, or as a combination of pressures for inextensible reinforcements.
Reinforcement strength check
Long-term design strength of geo-reinforcement Rt is calculated from the input parameters of the geo-reinforcement:
long-term design strength of reinforcement
short-term characteristic strength of geo-reinforcement
reduction coefficient of long-term deformation of reinforcement (determined based on geo-reinforcement lifetime)
reduction coefficient of the durability of reinforcement (determined based on soil pH)
reduction coefficient of failure of reinforcement when inserting into the soil (determined based on the grain sizes of soil)
overall coefficient of model uncertainty
Note: The FSUNC coefficient is not taken into account when calculating the reinforcement strength in the Redi-Rock Wall program.
Reinforcement bearing capacity against pull-out
The resistance of reinforcement against pull-out from the earth body is calculated from the input parameters of the geo-reinforcement and the normal force acting in the direction normal to its area:
bearing capacity against tearing
reinforcement length (from front face to its end)
coefficient of interaction between soil and geo-reinforcement
vertical geostatic stress
angle of internal friction of soil
Note: In the Redi-Rock Wall program, the pull-out resistance calculation takes into account the scale correction factor α.
Verification of bearing capacity of reinforcement against pull-out can be carried out according to the factor of safety or the theory of limit states.