Generally, if the single stone has not become movable, the revetment is stable, which is composed by the reno mattress, gabion and the riprap. This movement is limitation of the revetment.
In general, if a single stone no displacement occurs, by Reno mattress or guest or spread the ripped-rock revetment is composed of a stable, and that the beginning of the move, is the stability limit of pavement.
Tb= γwyi
Effect on the shear stress on the pavement is:
When yw as the density of water, I to bed slope, at the beginning of the rocks move in the critical state of traction shear stress is:
Tc=C*(γs-γw)dm
C* for protection factor, equivalent to the coefficient of friction, γs and γw are the density of rocks and water respectively, the dm for particle size of the scattered stone used median (50% consider the weight of the dissipation). An experiment shows that: in Fort Collins
(1) The spread of riprap protection factor is about 0.047, while filling the mesh cage, (Reno mattress/gabion) protection factor is about 0.10, that is two times the riprap.
This means that at any given under the action of water pressure, Reno mattress/gabion, the stone need average was only about half of the scattered stone. In addition, in the case of the same size stones, Reno mattress/gabion allows velocity at least three to four times for the same amount of scattered stone.
(2) The riprap initial mobile "status" is a kind of limit state, the individual unit graduall washed away by running water and make the lining was damaged.
For Reno mattres of the lattice structure, because of its structure after the initial mobile grid effect still exists, the deformation of Reno mattress will produce a new state of equilibrium, make it can stand the test of the more serious, will not reduce its resistance will not further deformation.
(3) Such as in Reno mattress/gabion fill small stones, the residual current velocity of the hidden layer of soil is small, provides more security, and can reduce pavement under the filter into the amount of lying.
(4) To fill the size of the stone or filling quantity decreases, even if it's just reduce a little, will also reduce the roughness of the lining of this capacity can be improved.
(5) The riprap design rules the minimum depth of 0.3 meters, the depth is commonly 1.5-2 times the average size of the stone. For underwater engineering, the depth should be increased by 50%, embankment slope can't more than 1:2.
But unlike the ripped-rock lining is scattered, reno mattress gabion pavement can be very thin devices(0.17 meters), the curve can be seen from the graph, because by scouring pads renault's pavemet of grass-roots/penn sliding dangerous scattered the ripped-rock lining more than small.
Reno mattress or disperses the pavement of ripped-rock stability, by increasing the lining depth or extend horizontally laid area to guarantee.
Note that in and a case (figure, use the scattered stone), must achieve a lower the expected the horizontal position enables delta erosion depth △z, and when to use reno mattress, the agency has complete can achieve erosion position.
Inthe second case(chart), the height of the scattered stone should be increased, and reno mattress are does not.
Since The Bas Erosion May Lead To Foot Slip Lining
Train z=Scour Depth Train X=Riverbed protective mention extensions degrees
Since The Base Erosion May Lead To Foot Slip Lining
* Test Value