Block Search in SVSLOPE® 2D

A feature of SVOFFICE™


Block Search

A block search is one of the powerful non-circular slip surface search methods available in SVLOPE® 2D. For example, it is especially useful to perform non-circular analysis along a thin weak layer. In order to define a non-circular slip surface with a block search, one or more block search objects must be defined. There are four block search objects available:

  • Block
  • Point
  • Line
  • Polyline


Block Search -- Block

A Block Search -- Block is an arbitrary four-sided convex polygon as shown in figure 1 where two Blocks are drawn. SVLOPE® 2D generates ONE slip surface vertex inside each Block Search -- Block for each slip surface. This ONE slip surface vertex can be randomly generated or specified by the user with number of increments in X direction and Y direction.

Figure 1

To add a new Block, user first click "New" button on the "Blocks" tab page, then the new Block's coordinates can be set by Draw on the canvas by click the "Draw" button. Or enter the coordinates directly in the data grid. Or can be Pasted into the data grid by press the "Paste" button as shown in Figure 2.
Each Block's line stroke can be set individually by setting the line color, line weight and line style.

Figure 2

Block Search -- Point

A Block Search -- Point is a single point, each slip surface generated by a Block Search must pass through this point. This block search object is very useful if we want to force the slip surface pass through the toe of a slope, or the bottom of a tension crack, etc. An example is shown in Figure 3, where each slip surface pass through the toe of the slope.

Figure 3

To add a new Point, user first click "New" button on the "Points" tab page, then the new Point's coordinates can be set by Draw on the canvas by click the "Draw" button. Or enter the coordinates directly in the data grid. Or can be Pasted into the data grid by press the "Paste" button as shown in Figure 4.
Each Point's stroke can be set individually by setting the point color and size.

Figure 4

Block Search --- Line

A Block Search -- Line is a line segment defined by two end points as shown in Figure 3 on top blue line. SVLOPE® 2D generates ONE slip surface vertex along each Block Search -- Line for each slip surface. This ONE slip surface vertex can be randomly generated or specified by the user with number of increments along the line.

To add a new Line, user first click "New" button on the "Lines" tab page, then the new Line's coordinates can be set by Draw on the canvas by click the "Draw" button. Or enter the coordinates directly in the data grid. Or can be Pasted into the data grid by press the "Paste" button as shown in Figure 5.
Each Line's line stroke can be set individually by setting the line color, line weight and line style.

Figure 5

Block Search -- Polyline

A Block Search -- Polyline consists of one or more line segments as shown in Figure 6. SVLOPE® 2D generates TWO slip surface vertexes along the polyline. These TWO slip surface vertexes can be randomly generated or specified by the user with number of increments along the polyline. The polyline points will be part of the slip surface points between these two generated slip surface vertexes. Block Search -- Polyline is useful to define slip surfaces that pass through complex thin weak material layer.

To add a new Polyline, user first click "New" button on the "Polylines" tab page, then the new Polyline's coordinates can be set by Draw on the canvas by click the "Draw" button. Or enter the coordinates directly in the data grid. Or can be Pasted into the data grid by press the "Paste" button as shown in Figure 7.
There are different options and combinations of specifying how the two vertexes are generated as shown in Figure 7. With these options user can have great flexibility and control on how the non-circular slip surface will be defined.

  • On Any Line Segment - generates a point anywhere along the polyline.
  • On Left/Right Line Segment - generates the Left / Right point anywhere on the leftmost / rightmost line segment of the polyline.
  • Left / Right End Point - the leftmost / rightmost point of the polyline will be used.
  • Each Polyline's line stroke can be set individually by setting the line color, line weight and line style.

    Figure 6

    Left / Right Projection Angles

    The Left and Right Projection Angles are used to project the slip surface up to the ground surface, from the left and right end points generated based on the above block search objects. The angle measurement convention is degrees counter-clockwise from the positive horizontal axis, for both the Left and Right Projection Angles, and it means that the End Angle is always greater and equal to the Start Angle. Project from the left point based on left angle to the ground surface to form the first line segment. A range of left projection angles is specified to form the left project angles, the project angles between the range can be randomly generated or user specified based on number of divisions. The left projection angle usually is greater than 90 degrees (as measured from the horizontal z-axis). Project from the right point based on right angle to the ground surface to form right end line segment. The right projection angle is usually less than 90° (from the horizontal x-axis).

    The Projection Angles are specified in the Options dialog as shown in Figure 8. The left and right angles will be displayed on the canvas. The locations of the left and right angles will be calculated automatically and are based on the leftmost and rightmost points. SVSLOPE 2D will find the leftmost and rightmost points based on currently defined Block Search objects.

    Figure 7

    Figure 8

    Block Search Objects -- Grouping

    The Grouping feature is used to group different Block Search Objects into different groups in order to analyze different slip regions of a model in one Block Search. To enable grouping, first Check the "Enable Multiple Groups" checkbox on the Options tab page as shown in Figure 8. After it is Checked, the Group ID combox on different Block Search Object tab pages will be enabled. The user then can set different groupd IDs in different Search Objects. The Block Search will be carried out independently for each group of Block Search objects. The total number of slip surfaces for each group is equal to Number of Surfaces specified on the Model Settings dialog divided by the number of groups if use random-generated points in block search objects, otherwise it is based on the number of increments user specified.

    The grouping is useful, for example, when there are two (or more) weak layers in one model, and the user wants to analyze it with one Block Search, then we can assign different group IDs to different Block Search objects defined for different weak layers.


     

    If you would like more information on this feature, feel free to contact us directly.