Internal stability of gabion

The internal stability of gabion wall can be examined with the help of:

- the theory of limit states

- factor of safety

Verification of joints between individual blocks is performed in the "Dimensioning" frame. The structure above the block is loaded by active pressure and corresponding forces are determined in the same way as for the verification of the entire wall. A loose filling is used in the analysis – not hand-placed rockfill – but its effect can be simulated using a very high angle of internal friction. It can be assumed that after some time due to action of filling aggregate the stress in meshes will drop down.  Individual sections of the gabion wall are checked for the maximum normal and shear stress. With the help of these variables it is possible to modify the slope of structure face by creating terraces or by increasing the slope of face of wall α.   

Assuming loading applied to the bottom block is schematically represented as:

Loading on the bottom block

Normal stress in the center of the bottom block is given by:

where:	N	-	normal force acting on the bottom block
	B	-	width of upper block
	e	-	eccentricity
	M	-	moment acting on the bottom block
	h	-	height of bottom block
	γ	-	unit weight of the bottom block material
	α	-	gabion slope

Pressure acting on the wall of the bottom block is determined as an increased active pressure:

where:	φd	-	design angle of internal friction of the bottom block material
	cd	-	design cohesion of the bottom block material
	γ	-	unit weight of material of the bottom block
	h	-	height of bottom block
	B	-	width of upper block
	α	-	gabion slope
	T	-	average value of pressure acting on face of the bottom block
	σ	-	maximal normal stress acting on the bottom block

Widths of meshes of the bottom block per one running meter of the gabion wall are:

where:	Dhor	-	width of upper mesh between blocks loaded in tension
	Dcelk	-	overall width of meshes loaded in compression T
	v	-	spacing of vertical meshes
	h	-	height of bottom block

The program allows for analysis of gabions with both simple and double mesh placed between blocks. For double meshes the inputted tensile strength of mesh (the "Edit material" frame) should be twice as large as the value assumed for simple meshes.

Geometry of gabions