Subgrade
Use this function to remove soil layers that are not strong enough to to carry a road by defining areas of vegetation, topsoil or soft spot soiltypes. This is an extended excavation based on design criterias and inputs, where the cross-section in a normal situation without using the function would otherwise not be in contact with the layers.
In the areas where a removal of these layers have been done the model will fill back with either quality fill or side fill in respective areas. For the quality fill it will separate the quantity that represent the fill layer above the existing terrainsurface, from those that are below.
Topsoil and Vegetation Removal
Use this function to:
Remove topsoil or vegetation layers in desired sections
Decide the slopes for how to cut through the material of topsoil and vegetation
Prerequisites
It is necessary to first define the topsoil and vegetation material in the Quadri model via the Sub Surface tool and to include the sub surface(s) as part of the calculation basis of the road task.
Vegetation layers are represented by using material type 21, 22, 23, 24, 25
Topsoil layers are represented by using material type 16, 17, 18, 19, 20
Good to know
This function can be accessed via the tab Topsoil and Vegetation Removal in the Subgrade dialog.
Vegetation and topsoil are most often used to remove loose materials with little load-bearing capacity. The material is often of a quality that you would reuse it in parts of the backfill of material along your model.
In section where both vegetation removal and topsoil is present, the topsoil needs to be located below the vegetation layer. The reasoning for this is that you do not have vegetation below any other layers.
Computation for removal of these two material types will stop at the topsoil material type.
Removal of topsoil and vegetation has one input dialog and will computationally be treated as one item in the profile calculation.
The quantities consider the actual soil types that is defined in the Quadri model and will split the solids accordingly.
The left and right side of the road will handle cut and fill situations independently.
You will see roadsurfaces with number 8.xx when removal is in use.
The topsoil and vegetation material types will be excavated down to firm soil (material type 1-5) or rock (material type 6-10).
If soft spot is present the topsoil and vegetation removal will excavate down to these layers also, but we recommend that the soft spot layers are also treated with the appropriate function also found in the Subgrade dialog.
In combination with soft spot removal the resulting excavation will be a combination of both methods, but for each respective layers (soft spot + topsoil/vegetation removal).
In the dialog it is possible to insert a new row or to delete an existing row via the 'Insert' and 'Delete' buttons.
When the cursor points to the corner of the cell, plus symbol will pop up, hold the symbol, and drag to copy the contents of the cell. This can be done for multiple cells in a row at one time.
Dialog inputs
First and Last: Define the First and Last sections for where a removal condition and slopes is to be applied to the topsoil and vegetation layers.
Fill: The side(s) of the road which in a normal situation will need a fill slope to reach the bottom of the removal layers, has different methods for how to handle the removal of topsoil and vegetation layers.
Fill - Cut: When removing the materials the fill surface (7.xx) will extend with the assigned fill slope to the bottom of the materials that is to be removed. To make the cut back up to the terrain it will use the same slope gradient as what is found on the cut surface (6.xx) of the road. The results of the excavation will be a V shape.
Fill - Vertical: When removing the materials the fill surface (7.xx) will extend with the assigned fill slope to the bottom of the materials that is to be removed. To make the cut back up to the terrain it will use a vertical surface. The results of the excavation will be a "half V" shape.
Vertical: When removing the materials it will go vertically down from where the 7.xx surface meets the terrain, until it reaches the bottom of the layers to be removed. To make the cut back up to the terrain it will use a vertical surface. The results will of the excavation will be a vertical excavation.
Cut: The side(s) of the road which in a normal situation will add a ditch or cut slope to reach the bottom of the removal layers, has different methods for how to handle the removal of topsoil and vegetation layers.
Cut: When removing the material from the bottom of the layers and up to terrain the slope of the excavation will be the same as the cut slope found in the road surface description.
Vertical: When removing the material from the bottom of the layers and up to terrain the slope of the excavation will be a vertical wall.
Criteria, Fill Height and Slope: When the criterias are met the function for removal of topsoil and vegetation will be activated.
Design standard: If either of these sub-criterias for height or slope are met;
The height of a fill is less than the assigned Fill Height. The default value is set to 3.000m.
The terrain slope gradient is steeper then the set value for Slope. The default value is set to 1:6 (0.167).
The slope gradient is considered based on the left/right extent of the road if it had been built without excavation.
Always: Will always remove the topsoil and vegetation layers where they exist.
As specified: Is identical to the Design Standard method in how it works, but allows the user to set a specified value for fill height and slope.
Soft Spot Removal
Use this function to:
Remove soft spot layers in desired sections
Decide the slopes for how to cut through the material of topsoil and vegetation
Prerequisites
It is necessary to first define the soft spot material in the Quadri model via the Sub Surface tool and to include the sub surface(s) as part of the calculation basis of the road task.
Soft spot layers are represented by using material types 11, 12, 13, 14, 15
Good to know
Use this function to remove loose soil, peat, fine soils with high humus content, wet clay, etc., to consider the soil bearing capacity underneath the road construction.
This function can be accessed via the tab Soft Spot Removal in the Subgrade dialog.
Loose fill with poor load-bearing characteristics underneath road constructions should, in individual cases, be replaced by for example rock fill.
Soil excavation should be carried out where the ground consists of peat, fine soils with a high humus content, or wet clay.
The material is often not of a quality that you would reuse it in parts of the backfill of material along your model.
The soft spot material type will be excavated down to firm soil (material type 1-5) or rock (material type 6-10).
The left and right side of the road will handle cut and fill situations independently.
You will see roadsurfaces with number 8.xx when removal is in use.
In combination with topsoil and vegetation removal the resulting excavation will be a combination of both methods, but for each respective layers (soft spot + topsoil/vegetation removal).
In the dialog it is possible to insert a new row or to delete an existing row via the 'Insert' and 'Delete' buttons.
When the cursor points to the corner of the cell, plus symbol will pop up, hold the symbol, and drag to copy the contents of the cell. This can be done for multiple cells in a row at one time.
NOTE: Soft spot removal has two methods for the computation
You have to decide if you want to use either a simple method or an advanced method for removing the soft spot layer. Switch method by pressing the button for Simple/Advanced. It is not possible to combine the simple and advanced method in one model, but you have to choose either one or the other to be used for the whole model. If you want to use different methods you need to have more then one road model.
When switching between the two methods it will ask you if it is OK to delete the content from the method you are currently in, before switching. Either accept and switch to the other method, or decline and stay in the method you are currently in.
Simple Method dialog
This method can be activated by pressing the Simple button on the lower left in the subgrade dialog.
First and Last: Define the First and Last sections for where a removal condition and slopes is to be applied to the soft spot layers.
Limit and Form: Decide on what type of excavation to perform on the soft spot layer
Type 1 - Extension of fill slope and normal cut slope: When removing the materials the fill surface (7.xx) will extend with the assigned fill slope to the bottom of the materials that is to be removed. To make the cut back up to the terrain it will use the same slope gradient as what is found on the cut surface (6.xx) of the road. The results of the excavation will be a V shape.
Type 2 - Extension of fill slope and vertical cut slope: When removing the materials the fill surface (7.xx) will extend with the assigned fill slope to the bottom of the materials that is to be removed. To make the cut back up to the terrain it will use a vertical surface. The results of the excavation will be a "half V" shape.
Type 3 - Vertical fill slope and vertical cut slope: When removing the materials it will go vertically down from where the 7.xx surface meets the terrain, until it reaches the bottom of the layers to be removed. To make the cut back up to the terrain it will use a vertical surface. The results will of the excavation will be a vertical excavation.
The principals for Limit and Form is much the same as found in the description of Cut/Fill for Topsoil and Vegetation removal.
Advanced Method dialog
This method can be activated by pressing the Advanced button on the lower left in the subgrade dialog.
The strength of this method is its ability to perform soft spot removal independently of fill slope gradients.
This is especially a key factor when fill slopes are designed with little steepness for run-off facilities or landscaping purposes.
In such cases, using the simple method will involve extensive excavation of soft spot material beyond what is necessary for road construction.
First and Last: Define the First and Last sections for where a removal condition and slopes is to be applied to the soft spot layers.
Depth: Specify the depth of the excavation
When not specifying any value it will say 'Complete', meaning that it will excavate the full depth of the soft spot layer.
When specifying a value (positive value) the depth is measured from the mode defined in the 'Depth from' column. The depth will be represented as a horizontal line.
Depth from: Only available if Depth is a value and not when using 'Complete'
1 - Terrain at centerline: The depth for the maximum excavation is measured down from the terrain surface at the centerline.
2 - Centerline elevation: The depth for the maximum excavation is measured down from the centerline elevation.
3 - Road surface at centerline: The depth for the maximum excavation is measured down from the road surface elevation at the centerline.
Ray: Defines the gradient of the soft spot excavation that will extend outwards and downwards from the left/right startpoints to the set depth of the excavation. The value of the ray is used for both left and right sides and must be set as a negative value.
The ray is only used as input for the computations and will not show on the cross-section profiles. By measuring backwards from the excavation endpoint and back up the startpoint on the road surface the user will be able to check the results.
Cut: Defines the gradient of the soft spot excavation that extends outwards and upwards from the bottom of the excavation to meet with the terrain surface. The value of the ray is used for both left and right sides and must be set as a positive value.
The ray is only used for quantity calculations and will not show on the cross-section profiles. However, the excavation will be visible and represent this cut value.
Left/Right side - Startpoint: Defines the starting point of the ray on the left/right side.
Select a road surface from the pull-down menu.
The outermost point of the surface, as seen from the centerline, will be the start point.
Left/Right side - Correction: Defines a horizontal displacement of the startpoint in meter, along the road surface, from the selected start point.
The offset value can be a positive (moving the point outwards from the centerline) or negative value (moving the point inwards towards the centerline).