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RocSupport

RocSupport

RocSupport is an analysis tool for estimating support requirements of tunnels in weak rock. Rock-support interaction analysis allows you to quickly run parametric analyses for different support types and rock parameters

RocSupport

Applications

Getting Support
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RocSupport is an easy-to-use software tool for estimating deformation in circular or near circular excavations in weak rock and visualization of the tunnel interaction with various support systems. Given the tunnel radius, in-situ stress conditions, rock parameters and support parameters, a ground reaction curve and a support reaction curve are calculated. The intersection of these curves determines a factor of safety for the support system.

RocSupport can be used as a tool for the preliminary design of tunnels and support systems. It can provide valuable information about various tunnel support options before detailed analysis is carried out with a finite element program such as RS2.

The program is applicable to tunnels excavated in weak rock under squeezing ground conditions. It is not applicable for excavations in hard rock, where failure is controlled by structural discontinuities or brittle failure.

Software Screenshots

RocSupport Figure 1: View tunnel cross-section and ground reaction curve.
RocSupport Figure 1: View tunnel cross-section and ground reaction curve.
RocSupport Figure 1: View tunnel cross-section and ground reaction curve.
RocSupport Figure 2: Results from probabilistic analysis in RocSupport.
RocSupport Figure 2: Results from probabilistic analysis in RocSupport.
RocSupport Figure 2: Results from probabilistic analysis in RocSupport.
RocSupport Figure 3: Cross-section of tunnel with support.
RocSupport Figure 3: Cross-section of tunnel with support.
RocSupport Figure 3: Cross-section of tunnel with support.
RocSupport Figure 4: Support parameters dialog.
RocSupport Figure 4: Support parameters dialog.
RocSupport Figure 4: Support parameters dialog.
RocSupport Figure 1: View tunnel cross-section and ground reaction curve. RocSupport Figure 1: View tunnel cross-section and ground reaction curve. RocSupport Figure 2: Results from probabilistic analysis in RocSupport. RocSupport Figure 2: Results from probabilistic analysis in RocSupport. RocSupport Figure 3: Cross-section of tunnel with support. RocSupport Figure 3: Cross-section of tunnel with support. RocSupport Figure 4: Support parameters dialog. RocSupport Figure 4: Support parameters dialog.

Applications

Product Highlights

  • What’s New in RocSupport v4.0
  • Probabilistic Analysis
  • Designing Supports
  • Analysis Options
  • Ground Reaction Curve

What’s New in RocSupport v4.0

RocSupport v4.0 features three new solution methods:

  • Vrakas and Anagnostou (2014)
  • Lee and Pietruszczak (2008)
  • Barbosa (2009)

The Vrakas and Anagnostou Method (2014) is especially beneficial, as it is used for tunnels with large strain.

RocSupport v4.0 also incorporates an updated Project Settings dialog with a Sampling, Random Numbers, and Project Summary tab, for convenience in modeling.

Additionally, when using a solution that uses the Mohr-Coulomb failure criteria, the user now has the choice of specifying the rock mass strength properties in terms of either cohesion or compressive strength.

Another notable change in the new version of RocSupport can be found in the Support features. The user can now define a custom type of a support by using the “custom” checkbox in the tab of a specific support type (e.g. a custom type of rockbolt).

Additionally, a database of common reinforcement types has been added for custom steelset support, to assist with the input of reinforcement properties. The database contains over 1000 entries.

Probabilistic Analysis

A Probabilistic Analysis allows you to enter statistical properties for the tunnel and rock parameters. Using Monte Carlo or Latin Hypercube sampling, statistical samples are generated for each probabilistic input parameter. The RocSupport analysis is repeated for each set of samples, and this results in a statistical distribution of calculated safety factors for the support system. A probability of failure for the support system is then calculated

Designing Supports

RocSupport allows you to simulate the application of rockbolts, steelsets or shotcrete around the circumference of the tunnel. Within each support category, you may select from one of several predefined support types, or create a user-defined custom support.

Predefined Support Types

Each specific support type has an associated maximum support pressure and maximum average strain. You can combine more than one support type in the same model.

Custom Support

If none of the predefined support types is suitable for the project, you can to define your own custom support type. This allows you to specify any combination of Maximum Support Pressure and Maximum Average Strain, which will define the support reaction curve.

Support Installation

The final required parameter is the point at which the support is installed, relative to the advancing tunnel face. This determines the origin of the support reaction curve on the rock-support interaction plot.

There are three methods of specifying the point at which the support is installed:

  • Distance from the tunnel face
  • At a specified tunnel convergence
  • At a specified tunnel displacement

Analysis Options

Solution Method

There are five solution methods used in RocSupport to compute the Ground Reaction Curve for the tunnel. They are:

  • Duncan Fama (1993)
  • Carranza-Torres (2004)
  • Vrakas and Anagnostou (2014)
  • Lee and Pietruszczak (2008)
  • Barbosa (2009)

Long Term Ground Reaction Curve

The solution methods in RocSupport compute the Ground Reaction Curve based on initial assumed material properties and loading conditions. To account for long term tunnel behaviour (e.g. rock mass property deterioration, re-establishment of groundwater regimes, creep, etc.), a strength reduction factor can be applied to obtain a long term Ground Reaction Curve.

Deterministic / Probabilistic Analysis

RocSupport can perform Deterministic or Probabilistic analysis. For a Deterministic analysis, all input values are assumed to be exactly known, resulting in a unique ground reaction curve and factor of safety for the support system.

For a Probabilistic Analysis, you may enter statistical distributions for input parameters (e.g. Tunnel and Rock Parameters). This results in a distribution of safety factors, from which a probability of failure for the support system can be calculated. See the RocSupport Probabilistic Analysis page for more information.

Ground Reaction Curve

At the heart of the “rock support interaction” analysis method used in RocSupport is the “ground reaction curve” or “characteristic line”, which relates internal support pressure to tunnel wall convergence.

The RocSupport solution methods compute the Ground Reaction Curve based on initial assumed material properties and loading conditions. To account for long term tunnel behaviour (e.g. rock mass property deterioration, re-establishment of groundwater regimes, creep, etc.), a strength reduction factor can be applied to obtain a long-term Ground Reaction Curve.

Getting Support
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