Publications

@article{Hutchinson2008,

title = {Geomechanics stability assessment of WWI military excavations at the Canadian National Vimy Site},

author = {DJ Hutchinson and MS Diederichs and P Pehme and P Sawyer and P Robinson and P Puxley and H Robichaud},

url = {https://www.sciencedirect.com/science/article/pii/S1365160907000755},

doi = {HTTPS://DOI.ORG/10.1016/j.ijrmms.2007.04.014},

issn = {1365-1609},

year  = {2008},

date = {2008-01-01},

journal = {International Journal of Rock Mechanics & Mining Science},

volume = {45},

number = {1},

pages = {59-77},

abstract = {The Canadian National Memorial Site, Vimy Ridge, France, commemorates the efforts and loss of life of Canadian troops in the First World War (WWI). The site comprises the monument, a Visitors Centre, the Grange Tunnels and restored trenches and several cemeteries. A substantial portion of the battlefield terrain remaining from WWI is preserved at this site, including trenches, shell holes and military mining craters. The ground surface is further disturbed by subsidence of the ground surface into underground excavations left from the war. A significant number of subsidence events have been recorded within the last decade. There is concern that ground surface subsidence could compromise the safety of visitors or workers at the site. 

 

The excavations of concern include dugouts, headquarters and hospitals, and were excavated in chalk. Possible excavation types, dimensions and support were investigated in the historical literature. To assess the potential for ground subsidence, the geological setting was investigated and the chalk was mapped and sampled, to determine the geomechanical characteristics of the material. The chalk was accessed in quarry excavations and in tunnels and declines that have been discovered and re-opened in recent years. Finally, the influence of excavation geometry and depth, chalk condition and effects of weathering on the excavation stability were assessed using numerical simulation, using a finite element program, and considering voussoir beam stability. Interpretation of the results of this analysis allow development of general relationships between span, depth and possible failure to isolate excavation classes that pose a long-term hazard, and to reduce the priority for those that are unlikely to fail to surface as well as those that are likely to have failed soon after construction.},

keywords = {Historical, Risk assessment, Stability, Subsidence, tunnelling, WW1},

pubstate = {published},

tppubtype = {article}

}

@article{Diederichs2007,

title = {The 2003 Canadian Geotechnical Colloquium: Mechanistic interpretation and practical application of damage and spalling prediction criteria for deep tunnelling},

author = {MS Diederichs},

doi = {10.1139/T07-033},

year  = {2007},

date = {2007-11-08},

journal = {Canadian Geotechnical Journal},

volume = {44},

number = {9},

pages = {1082-1116},

abstract = {Spalling and strain bursting has long been recognized as a mechanism of failure in deep underground mines in hard rock and in deep infrastructure tunnels. The latter is a significant growth industry, particularly in Europe where subalpine base tunnels in excess of 10 m wide and dozens of kilometres long are being driven by tunnel boring machine (TBM) through alpine terrain at depths greater than 2 km. In more massive granitoid or gneissic ground, these tunnels have experienced significant spalling damage. En route to a practical predictive technique for this condition, the author utilizes a number of analytical and micromechanical tools to validate a simple empirical predictive model for tunnel spall initiation. The true nature of damage and of yield, as the result of extensile damage accumulation, in hard rocks is examined using these tools. Based on the resultant conceptual model, the author expands on the empirical damage threshold, using a spalling limit to differentiate stress paths that lead to crack propagation and spalling from those that incur stable microdamage prior to conventional shear failure at higher relative confinements. Finally, the composite and robust in situ yield model is applied to nonlinear modelling for support design.},

keywords = {Crack initiation, Numerical modelling, Rock fracture, spalling, tunnelling, Yield},

pubstate = {published},

tppubtype = {article}

}

@article{Hutchinson2007,

title = {Integrated geomechanics/geomatics approach to understanding the movement of a large, complex slowly moving landslide},

author = {DJ Hutchinson and MS Diederichs and R Harrap and C Carranza-Torres and KS Kalenchuk},

year  = {2007},

date = {2007-01-01},

journal = {Journal of Geophysical Research Abstracts},

number = {9-05871},

keywords = {landslide},

pubstate = {published},

tppubtype = {article}

}

@article{Lato2006,

title = {Evaluating block shape and block volume distributions of rock faces},

author = {MJ Lato and DJ Hutchinson and MS Diederichs and KS Kalenchuk},

issn = {1607-7962},

year  = {2007},

date = {2007-01-01},

journal = {Journal of Geophysical Research Abstracts},

volume = {9},

number = {01171},

abstract = {The use of Light Detection And Ranging (LiDAR) has expanded rapidly since 1994, when it became commercially available. The equipment mobility, as well as accuracy and rate of data collection, in comparison to conventional surveying and stereophotogrammetric methods, have enabled the application of LiDAR to traditionally unrelated fields of study. For instance, LiDAR is currently employed in applications from precise volumetric analysis in open pit mines to archaeology projects in ancient ruins. This abstract discusses a geotechnical engineering application of LiDAR which has relevance to rock cuts along infrastructure corridors and in open pit mines. The focus of this work is to determine the distribution of block size and block shape for a given rock cut, since each of these factors has crucial implications to the potential hazard at a specific location, should a failure occur. This work will provide geological input into hazard rating for Canadian National railroad tracks. 

 

The process of resolving block shape and block volume distributions, is a four-step procedure. The process can be applied to any rock face that is controlled by visible and distinct discontinuities. 

 

The first step is the collection of data. LiDAR data can be collected via aerial methods (fixed wing aircraft and helicopters), mobile terrestrial scanners (mounted in the bed of a pickup truck), and stationary terrestrial scanners (mounted on a tripod)4. The scanner must be properly aligned with respect to the discontinuities in the rock face to accurately estimate their orientation and spacing. A high resolution scan from a distance of roughly 10m has an accuracy of 12-15mm and takes between 18-25 minutes and will scan ∼30m^2. Optimal results are achieved when the scans are taken from mutually oblique alignments to the rockface. For the purpose of the exercise reported here, an Optech ILRIS stationary terrestrial scanner was used to collect the data. The data was collected 25km north of Kingston, Ontario, Canada. 

 

The second step is the manipulation and “cleaning” of the raw point cloud data. Redundant data points and noise are selected and filtered to increase the visibility of zones of significance. This removal of noise allows the features of importance, such as joint surfaces to be readily recognized, identified and plotted. 

 

The third step is the delineation of discontinuities and/or joint surfaces. Split-FX (Split Engineering) is a point cloud analysis program that enables the user to define surfaces based on mathematically derived variables. Surface orientation data are output to a stereonet plot. Joints are grouped into sets and the statistical average orientation is reported for each set. Joint spacing can also be statistically estimated; however, this process requires more intense user input. 

 

The fourth and most demanding step is the numerical simulation of the rock face. Itasca’s 3DEC code is used to generate a statistical representation of the scanned rock face based on the data delineated in Split-FX. The model will assume a flat faced outcrop with fully persistent joints. As the model is run, all failed blocks are documented and characterized using block shape and volume distribution graphs based on the approach developed by Kalenchuk et al (2006). This process quantifies the geometric distribution of discrete blocks within a failed mass. 

 

The results of this work enable a more refined rock fall hazard assessment, wherein block shape and size are independent inputs. This will allow for more effective inclusion of rock mass parameters into rock fall hazard rating system developed by BGC6 and employed by CN6 . This process enables advanced geotechnical structural mapping of areas that were previously inaccessible or too hazardous to approach.},

keywords = {Block size distribution, Corridor analysis, LiDAR, Rock block shape, rock cuts},

pubstate = {published},

tppubtype = {article}

}

@article{Kalenchuk2006,

title = {Characterizing block geometry in jointed rockmasses},

author = {KS Kalenchuk and MS Diederichs and S McKinnon},

url = {https://www.sciencedirect.com/science/article/pii/S1365160906000566},

doi = {https://doi.org/10.1016/j.ijrmms.2006.04.004},

issn = {1365-1609},

year  = {2006},

date = {2006-12-01},

journal = {International Journal of Rock Mechanics and Mining Sciencesv},

volume = {43},

number = {8},

pages = {1212-1225},

abstract = {The intersection of discontinuities in a jointed rockmass creates in situ blocks of variable three-dimensional (3D) geometry. The size and shape of rock blocks in a rockmass assembly have a dominant influence on the engineering properties of a rockmass, and control, for example the failure geometry of a rock face and the optimum associated support and surface restraint strategy. The distribution of block volumes within a rockmass can be effectively analyzed and communicated using a cumulative volume distribution curve. Integrated with this analysis, a methodology has been developed to characterize the shape and volumetric shape distribution of rock blocks in 3D models of jointed rockmasses. The proposed Block Shape Characterization Method takes into account two factors: the first, α, describes the shortening of the minor principal axis of the block while β describes the elongation of the major axis. When merged with the block volume distribution, the Block Shape Characterization Method can effectively describe and classify both the size and shape distributions of any jointed rockmass and is not limited to orthogonal blocks or hexahedra. This methodology can classify any polyhedra and has been developed and calibrated based on synthetic joint data and simulated block assemblies. A demonstration is given of its effectiveness in characterizing block geometries in the field using mapped fracture data.},

keywords = {Block size distribution, Rock block shape},

pubstate = {published},

tppubtype = {article}

}

@article{Hoek2006,

title = {Reply to the Discussion by H. Sonmez and C. Gokceoglu on “Empirical estimation of rock mass modulus”},

author = {E Hoek and MS Diederichs},

url = {https://www.sciencedirect.com/science/article/pii/S1365160905001528},

doi = {HTTPS://DOI.ORG/10.1016/j.ijrmms.2005.10.003},

year  = {2006},

date = {2006-06-01},

journal = {International Journal of Rock Mechanics & Mining Science},

volume = {43},

number = {4},

pages = {667-678},

keywords = {Disturbance factor, Geological Strength Index, Uniaxial compressive strength of intact rock},

pubstate = {published},

tppubtype = {article}

}

@article{Hoek2006203,

title = {Empirical estimation of rock mass modulus},

author = {E Hoek and MS Diederichs},

doi = {10.1016/j.ijrmms.2005.06.005},

issn = {1365-1609},

year  = {2006},

date = {2006-02-01},

journal = {International Journal of Rock Mechanics and Mining Sciences},

volume = {43},

number = {2},

pages = {203-215},

abstract = {The deformation modulus of a rock mass is an important input parameter in any analysis of rock mass behaviour that includes deformations. Field tests to determine this parameter directly are time consuming, expensive and the reliability of the results of these tests is sometimes questionable. Consequently, several authors have proposed empirical relationships for estimating the value of rock mass deformation modulus on the basis of classification schemes. These relationships are reviewed and their limitations are discussed. Based on data from a large number of in situ measurements from China and Taiwan a new relationship, based upon a sigmoid function, is proposed. The properties of the intact rock as well as the effects of disturbance due to blast damage and/or stress relaxation are also included in this new relationship.},

keywords = {Empirical relationships, In situ measurements, Rock mass modulus},

pubstate = {published},

tppubtype = {article}

}

@article{Hutchinson2006,

title = {Landslide Hazard Management},

author = {DJ Hutchinson and MS Diederichs and C Carranza-Torres and C Sheriff and N Kjelland and R Harrap},

year  = {2006},

date = {2006-01-01},

journal = {Felsbau},

volume = {24},

number = {3},

pages = {24-29},

keywords = {hazard assessment, landslide, risk management},

pubstate = {published},

tppubtype = {article}

}

@article{Diederichs2004,

title = {Damage initiation and propagation in hard rock during tunnelling and the influence of near-face stress rotation},

author = {MS Diederichs and PK Kaiser and E Eberhardt},

doi = {10.1016/j.ijrmms.2004.02.003},

year  = {2004},

date = {2004-07-01},

journal = {International Journal of Rock Mechanics and Mining Sciences},

volume = {41},

number = {5},

pages = {785-812},

abstract = {One of the critical design problems involved in deep tunnelling in brittle rock with continuous excavation techniques, such as those utilizing tunnel boring machines or raise-bore equipment, is the creation of surface spall damage and breakouts. The mechanisms involved in this process are described in this paper. The onset and depth of damage associated with this phenomenon can be predicted, as a worst case estimate, using a factored in situ strength value based on the standard uniaxial compressive strength (UCS), of intact test samples. The factor applied to the UCS to obtain the lower bound in situ strength has been shown repeatedly to be in the range of 0.35–0.45 for granitic rocks. This factor varies, however, across different rock classes and must be determined or estimated for each class. Empirical guidance is given for estimating the in situ strength factor based on the UCS for different rock types and for different descriptive parameters. Laboratory testing procedures are outlined for determining both this lower bound strength factor and the upper bound in situ strength. This latter threshold is based on the definition of yield based on crack interaction. These techniques are based, in part, on theoretical principles derived from discrete element micromechanical experimentation and laboratory test results. The mechanisms that lead to in situ strength drop, from the upper bound defined by crack interaction and the lower bound limited by crack initiation, are described. These factors include the influence of tunnel-induced stress rotation on crack propagation, interaction and ultimately coalescence and failure. A case study illustrating the profound impact of near-face stress rotation is presented.},

keywords = {Brittle damage, Brittle damage initiation, Brittle Damage propagation, Near-face stress rotation, spalling, tunnelling},

pubstate = {published},

tppubtype = {article}

}

@article{Diederichs2003,

title = {Rock fracture and collapse under low confinement conditions},

author = {MS Diederichs},

doi = {10.1007/s00603-003-0015-y},

year  = {2003},

date = {2003-12-01},

journal = {Rock Mechanics and Rock Engineering},

volume = {36},

number = {5},

pages = {339-381},

abstract = {The primary objective of this work was an examination of the complimentary roles of tensile damage and confinement reduction (or stress relaxation) on excavation response of ‘‘hard’’ rockmasses. Tensile damage and relaxation are examined with respect to structurally controlled or gravity driven failure modes as well as to strength controlled or stress driven rockmass damage and yield. In conventional analysis of both structurally controlled and stress driven failure, the effects of tensile damage and tensile resistance as well as the elevated sensitivity to low confinement are typically neglected, leading to erroneous predictions of groundfall potential or rock yield. The important role of these two elements in underground excavation stability in hard rock environments is examined in detail through a review of testing data, case study examination and a number of analytical and numerical analogues including discrete element simulation, statistical theory and fracture mechanics. This rigorous theoretical treatment updates, validates and constrains the current use of semi-empirical design guidelines based on these mechanisms.},

keywords = {discrete elements, Rock fracture, strength, underground stability},

pubstate = {published},

tppubtype = {article}

}

@article{Hutchinson2003,

title = {Geotechnical In-Situ Technology (GIST) Network – Development of real-time GIS tools for interpreting slope instability from geo-databases},

author = {DJ Hutchinson and MS Diederichs and R Harrap and D Ball},

url = {https://www.researchgate.net/publication/241201947_Geotechnical_In-Situ_Technology_GIST_Network_Development_of_real-time_GIS_tools_for_interpreting_slope_instability_from_geo-databases},

year  = {2003},

date = {2003-04-01},

journal = {Journal of Geophysical Research Abstracts},

number = {7397},

abstract = {Slope stability hazard assessment is generally based on an understanding of the expected slope failure mechanism, and the strength of the soil and rock materials under different moisture conditions. Slope stability may be reduced by factors external to the slope, including earthquake loading and modifications to the slope geometry, either by human activities or natural erosion processes. Stability analysis may be based on regional or more localized approaches, both of which may be based in development and analysis of a geo-database. On a regional scale, assessment is based on analysis of surface data, including geomorphological evidence of pre-existing or ongoing slope failures, slope angle, distribution of surficial geology, vegetative cover and precipitation. Assessment of the relative importance of these factors is based on understanding the slope failure mechanisms. Geospatial analysis tools have been implemented in GIS programs to assess the relative likelihood of slope instability and to create slope hazard maps. On a local scale, assessment of slope instability may be based on the results of geotechnical instrumentation of the surface and sub-surface materials. For complex, heavily instrumented slopes, compilation of the relevant information, including slope movement, piezometric pressure, precipitation and temperature, into a geo-database is required. Analysis of the information collected, coupled with parametric analyses of slope instability using numerical simulation tools, is required to assess the potential for slope instability. These analyses generally result in a quantitative assessment of instability in the form of factor of safety or probability of failure. Case history examples of the application of GIS tools written for analysis of slope instability at both the regional and local scale will be provided in this paper. At the regional scale, analysis of the potential for instability of sensitive clay slopes along river valleys resulting in slope hazard maps will be presented. At the local scale, the development of a GIS platform for analysis of geotechnical data and provision of early warning based on analysis of multiple geotechnical sensors will be discussed. The application of this approach to analysis of a heavily instrumented, potentially unstable slope located on the banks of a hydropower reservoir, just upstream of the dam, will be discussed.},

keywords = {Geographic information system (GIS), hazard assessment, Risk assessment, Slope stability},

pubstate = {published},

tppubtype = {article}

}