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SLOPE is a computer program for analysing the stability of slopes. The program is also applicable to earth pressure and bearing capacity problems. Optional facilities are available for the analysis and design of reinforced soil.
Analysis Options ( Top )
The program provides a choice of methods of analysis including the following:
The various methods make different assumptions about the equilibrium distribution of forces within the slipping mass. The result of each analysis is expressed as a factor of safety. In routine slope stability problems the factor of safety is calculated with respect to the strength of the soil along the slip surface. There is an option to calculate the factor of safety with respect to surcharge loads. This option is applicable to bearing capacity problems and earth pressure calculations.
Strata Profile and Groundwater Conditions ( Top )
The ground can be described in terms of up to nine soil strata with different strength properties. In simple cases pore pressures are calculated from the position of the water table but in more complicated flow conditions (e.g. the presence of an aquifer or pore pressures due to construction), local values of pore pressure can be defined. Perched water tables and artesian pressures can be modelled by specifying additional piezometric surfaces associated with individual strata.
Where detailed information about the pore pressure distribution is lacking, the pore pressures in any individual stratum can be expressed as an Ru value. For fine grained soils which sustain negative pore pressures, the maximum suction can be specified. Submerged slopes can be analysed by specifying a water table above ground level.
Strata profiles and water tables can be imported from DXF and DWG files.
Surcharge Loads & Earthquake forces ( Top )
External forces (due to buildings or strut forces in excavations) can be applied to the ground surface. Earthquake forces can be modelled in a quasistatic manner by specifying horizontal and vertical acceleration factors.
Slip Surfaces ( Top )
Circular and noncircular slip surfaces can be analysed. A group of circular slip surfaces can be analysed by defining a rectangular grid of centres. For each centre a number of different radii can be specified. Alternatively the circles can be made to pass through a common point or touch a common tangent.
Two and three part wedges can be analysed. A group of wedges can be analysed by defining a rectangular grid of wedge nodes. For each wedge node a number of different wedges can be analysed by specifying ranges of wedge angles and toe positions.
General noncircular slip surfaces are specified individually by the user.
Reinforced Soil Options (SLOPE version 12R only) ( Top )
Horizontal layers of reinforcement can be included in the soil
profile. The program is equally applicable to reinforced Slopes
and reinforced soil Walls. There is no fundamental difference in
the treatment of Slopes and Walls. The required degree of
stability for each type of structure is achieved by the selection
of appropriate factors of safety in each case.
The program can be operated in Analysis or Design Mode and can
provide designs conforming to most codes of practice.
The program caters for a variety of types of reinforcement
Design Mode  reinforced slope or embankment on a stable foundation ( Top )
The program selects appropriate types, lengths and spacings of
reinforcement layers to achieve a required Factor of Safety for
both internal and external stability of the given slope profile.
This design option is applicable to natural slopes, walls and
manmade embankments where the foundation soil is stable i.e.
where there is no risk of a failure surface developing below or
beyond the toe of the reinforced slope.
Output from the program gives the elevations and lengths of all
the reinforcement layers and details of the critical wedge at
each reinforcement elevation.
Embankments on soft foundations can be dealt with using the
Analysis Mode.
Analysis Mode ( Top )
In the analysis mode the program analyses a slope containing a
predefined layout of reinforcement. (The layers of reinforcement
were chosen either by the user or are the result of the programs
own design procedure). A wide range of slip surfaces can be
generated automatically to explore all possible failure
mechanisms and calculate the lowest factor of safety.
The results are presented as a grid of factors of safety in the
usual way. If the calculated factors of safety are not adequate
it is up to the user to modify the slope or reinforcement to
produce a stable arrangement.
Factor of safety of reinforced soil ( Top )
The factor of safety for a reinforced soil slope is calculated
taking into account the combined restoring effect of
reinforcement and soil strength. Soil and reinforcement strengths
may be partially factored to produce balanced designs in
accordance with code requirements. Partial factors may also be
applied to surcharge loads and soil weight.
The stabilising effect of the reinforcement is calculated
according to Department of Transport Technical Memorandum BE 3/78
and BS8006.
The Factor of Safety calculation allows the user to specify a
certain amount of interslice friction which leads to safe but
more economical designs.
Types of reinforcement ( Top )
The program deals with three main types of reinforcement:
The program includes a data base of properties of some commonly available types of reinforcement.
Automatic wedge generation ( Top )
When analysing reinforced slopes it is often more appropriate to consider wedge shaped slip surfaces rather than circular slip surfaces. The choice is up to the user, but your attention is drawn to the facility for automatic generation of two part wedges with wedge nodes at equally spaced positions along the reinforcement layers, and toe exit points at the ends of the layers.
Data Input and Editing ( Top )
Data values are checked for permissible ranges. A list of
data Errors and Warnings is displayed if unacceptable or
inappropriate data combinations are detected. Data can be checked
visually at any time during data entry or editing.
Import data from drawing files
Data may be imported from .DXF and .DWG drawing files generated
by AutoCad or other software.
Units
Data may be entered in any consistent set of units e.g. (kN,m),
(lb,feet). All printout from the program is automatically annotated
in the appropriate units.
Output from the Program ( Top )
Printed output from the program consists of the following:
Graphics ( Top )
Data and results are
displayed in graphical form either on the screen or in hard copy form.
Graphical display shows:
Hot Keys ( Top )
Special Hot Keys give instant access to Help facilities, Error reporting, Data plotting (during edit) and Summary output (during analysis).
Help ( Top )
Help is provided at two levels: Press F1 at any time for context sensitive help on data entry or current activity. Press Alt+H at any time to use the Help Index. Subjects covered include advice on the selection of values of earth pressure coefficients and soil modulus.
Hardware Requirements ( Top )
SLOPE operates on all Windows systems. Program files occupy about 3Mb of disk space. Operation of the program requires about 10Mb of RAM.