%0 Journal Article %J International Journal of Rock Mechanics and Mining Sciences [1997] %D 2010 %T Comparison of three fracture sampling methods for layered rocks %A Alex K Manda %A Stephen B Mabee %K #StaffPubs %K Big Quarry %K carbonates %K case studies %K data acquisition %K data processing %K dolomite %K Door Peninsula %K fractures %K geographic information systems %K ground water %K information systems %K joints %K layered materials %K mapping %K methods %K movement %K multiple scanline method %K northeastern Wisconsin %K numerical models %K permeability %K sampling %K selection method %K simulation %K single scanline method %K statistical analysis %K Structural geology 16 %K style %K three-dimensional models %K United States %K Wisconsin %X Three methods of fracture data collection are tested against each other in layered dolomitic rocks to evaluate the effectiveness of each method in sampling fracture properties. The methods tested are the single scanline method (SSM), selection method (SM), and multiple scanline method (MSM). Finite element techniques were first used to build a base model with the exact locations, sizes and orientations of each fracture observed in the natural fracture network. Then, a second set of models were stochastically generated using statistics from each sampling technique. For each network, the overall fracture intensity was used to assess the effectiveness of each sampling technique in capturing the real fracture properties. Fracture network permeability was also calculated for each of two directions to evaluate the transmissive properties of the networks. Although all three methods produced good matches of relative intensity and permeability between natural and synthetic fractures, the results reveal that a well-placed scanline performed the best at recreating natural fractures. However, the results from one variation of the SSM were only slightly better than the results from both versions of the SM. In general, the SSM provides the best results but possibly at heavy costs in time and labor, whereas the SM gives comparable results with less expenditure of energy and time. Thus, the SM is an adequate technique and recommended for use at large outcrops or where time, access or budget constraints are a concern. %B International Journal of Rock Mechanics and Mining Sciences [1997] %I Elsevier : Oxford-New York, International %C International %V 47 %P 218 - 226 %8 2010/02/01/ %@ 13651609 %G eng %U http://www.sciencedirect.com/science/article/pii/S1365160909001804 %N 22 %! International Journal of Rock Mechanics and Mining Sciences [1997] %0 Journal Article %J Journal of Structural Geology %D 2008 %T Influence of rock fabric on fracture attribute distribution and implications for groundwater flow in the Nashoba Terrane, eastern Massachusetts %A Alex K Manda %A Stephen B Mabee %A Donald U Wise %K #StaffPubs %K foliation %K fractures %K ground water %K Hydrogeology 21 %K joints %K massachusetts %K movement %K Nashoba terrane %K preferred orientation %K statistical distribution %K structural analysis %K Structural geology %K style %K terranes %K United States %X Attributes (i.e. trace-length, spacing, termination and orientation) of joints and foliation-parallel fractures (FPFs) are used to assess the influence of lithology and fabric on fracture type and distribution in metamorphic and igneous rocks of the Nashoba terrane, Massachusetts. Orientations of NE-SW and NW-SE trending joints are consistent throughout the region, whereas FPFs are sub-parallel to the axis of the terrane. Joint spacing generally decreases to the northeast across the terrane reflecting lithologic changes from metamorphic to igneous rock types. Although trace-length and spacing frequency distributions of both joints and FPFs are best described by lognormal functions, FPFs possess narrower fracture spacing than joints. Median fracture trace-lengths of all FPFs are comparable to those of all steep joints, but the median fracture spacing is half that of all steep joints. Trace-lengths of FPFs vary as a function of the degree of development of foliation. Fracture attributes and groundwater flow models suggest that FPFs may significantly increase fracture connectivity and potential for groundwater recharge. FPFs may account for as much as 30% of flow in fracture networks suggesting that in addition to joints, FPFs play a significant role in groundwater hydraulics that may include imparting flow anisotropy on the groundwater system. %B Journal of Structural Geology %I Elsevier : Oxford, International %C International %V 30 %P 464 - 477 %8 2008/04/01/ %@ 01918141 %G eng %U http://www.sciencedirect.com/science/article/pii/S0191814107002362 %N 44 %! Journal of Structural Geology