extraction and statistics of discontinuity orientation and trace length from typical fractured rock mass a case study of the xinchang underground research laboratory site china abstract the geological parameters of rock discontinuities are of great significance for the evaluation of high level radioactive waste repository and underground research laboratory url site characteristics to provide sufficient basis for the construction of the xinchang url site this paper presents a comprehensive set of methods for acquisition of discontinuity parameters in this set of methods a high precision three dimensional point cloud model of an outcrop with real geographic information is established based on close range photogrammetry technology from which not only planar discontinuities but also linear discontinuities can be identified and extracted by a semi automatic method a new fast fuzzy clustering method is proposed to cluster discontinuity sets the statistics method based on topographic window projection is improved to increase the rationality of estimating the geometric characteristics of fracture traces as a preliminary validation the results of this case study reveal that these methods have good applicability in acquiring discontinuity parameters which is also conducive to the establishment of a deterministic stochastic discrete fracture network dsdfn model to further analyze the properties of fractured rock mass in addition it is preliminarily found that some outcrops different locations have structures with similar geological features to a certain extent moreover the fractures exposed on the outcrop surface have distribution characteristics similar to those in the granite body obtained by drilling above all the presented multidisciplinary methods could provide an alternative and practical approach for low cost and accurate acquisition of discontinuity parameters and thus to study the properties of fractured rock mass effectively

surface based transport model for mixed size sediment we present a transport model for mixed sand gravel sediments fractional transport rates are referenced to the size distribution of the bed surface rather than subsurface making the model completely explicit and capable of predicting transient conditions the model is developed using a new data set of 48 coupled observations of flow transport and bed surface grain size using five different sediments the model incorporates a hiding function that resolves discrepancies observed among earlier hiding functions the model uses the full size distribution of the bed surface including sand and incorporates a nonlinear effect of sand content on gravel transport rate not included in previous models the model shares some common elements with two previous surface based transport models but differs in using the full surface size distribution and in that it is directly developed from a relatively comprehensive data set with unambiguous measurement of surface grain size over a range of flow transport rate and sediments

experimental and numerical evidence for intrinsic nonmigrating bars in alluvial channels alternate bars in straight alluvial channels are migrating or nonmigrating the currently accepted view is that they are nonmigrating if the width to depth ratio is at the value of resonance or if the bars are forced by a persistent local perturbation we carried out 2 d numerical computations and a long duration mobile bed flume experiment to investigate this view we find that nonmigrating bars can also occur in straight channels without resonant width to depth ratio or steady local perturbation they appear to be an intrinsic response of the alluvial river bed this finding bears on explanations for meandering of alluvial rivers for which nonmigrating bars are seen as a prerequisite we find however that the intrinsic tendency of a straight channel to form meanders usually has a different origin the identified intrinsic nonmigrating bars can only become the dominant mechanism for incipient meandering if the erodibility of the banks is very low

geostatistical method for inferring rmr ahead of tunnel face excavation using dynamically exposed geological information abstract rock mass rating rmr is a rock mass classification system that is often used to select appropriate excavation methods and rock support systems in tunnel projects this paper presents a geostatistical method for inferring rmr values quantitatively ahead of excavation of the tunnel face the study makes full use of geological information exposed on excavated tunnel faces to capture the spatial correlation of rock mass quality and later predicts the rmr value using the kriging method predictions are constantly updated during the tunnel construction process the advantages of the proposed method are as follows 1 the rmr prediction uncertainty is quantified by accounting for spatial variability and model uncertainty therefore the resulting prediction can consider the geological conditions of the worst scenario 2 the spatial variability of the geological condition is represented as a variogram model that is updated by observation data on the new excavated faces and as the tunnel advances the rmr prediction accuracy improves and 3 the periodicity of geological conditions can be considered in rmr prediction the proposed method is applied to a rock tunneling project the mingtang tunnel in anhui province china the method achieves approximately 80 prediction accuracy therefore it has high potential as a tool for predicting rmr information ahead of tunnel face excavation

composition of size fractioned sedimentary organic matter in coastal environments is affected by difference in physical forcing strength the diagenesis of sedimentary organic matter som in three different depositional environments in south texas and dominated by vascular plant input was investigated sediments were collected from mcguill lake a small freshwater lake and two salt marsh sites in nueces delta and copano bay and size fractioned by wet sieving physical forcing or energy indicated by tides tidal current and wind and wind fetch area is weakest in the lake intermediate strength at the nueces delta and strongest at copano bay results from total hydrolyzable amino acid thaa and n alkane analysis and 13c solid state nuclear magnetic resonance spectroscopy nmr showed that the som from all three sites became more degraded towards finer size fractions from 300 m 300 125 m 125 63 m 63 32 m to 32 m relative to the coarse fractions the fine fractions were enriched in the degradation indicator aminobutyric acid and in aliphatic and proteinaceous components as shown from nmr spectra and lower c n ratio values this degradation pattern of som with size is typical for sediments from coastal and lacustrine environments however the contents of organic carbon oc thaas and n alkanes were higher in sandy fractions than in silt and clay fractions from mcguill lake sediment suggesting that the som was relatively undegraded in coarse fractions the size distribution of om in the lake could be explained by the weak physical forcing which may not easily break down coarser plant detritus into smaller pieces the trend contrasted with degradation patterns for sediments from nueces delta and copano bay where som was concentrated in the 32 m fraction which may be due to the strong physical forcing the physical forcing effects could also explain the attachment of clay minerals to sand grains in both the lake and nueces delta because of the relatively weak physical forcing effects while no clay attachment to sand grains was found at the copano bay site because of the strong physical forcing effects physical forcing may be an important mechanism in the processing and transport of om from vascular plants and other organic sources in estuaries and bays before the som is exported to coastal oceans

numerical simulation of bar and island morphodynamics in anabranching megarivers 1 bar and island morphodynamics in the world s largest anabranching rivers are investigated using a new numerical model of hydrodynamics sediment transport bank erosion and floodplain development operating over periods of several hundred years simulated channel morphology is compared to that of natural rivers and shown to be realistic both in terms of the statistical characteristics of channel width depth and bar shape distributions and mechanisms of unit bar compound bar and island evolution results demonstrate that bar and island stability may be sensitive to hydrologic regime because greater variability in flood magnitude encourages the formation of emergent bars that can be stabilized by vegetation colonization simulations illustrate a range of mechanisms of unit bar generation that are linked to local bed or bank instabilities this link may explain the reduced frequency of unit bars observed in some large anabranching rivers that are characterized by stable vegetated islands and slow rates of channel change model results suggest that the degree to which sand sized bed material is carried in suspension likely represents an important control on bar morphodynamics and channel network evolution because of its influence on sand transport direction consequently differences in the partitioning of the total sand load between bed load and suspension may provide a partial explanation for contrasting styles of anabranching in the world s largest sand bed rivers these results highlight a need for spatially distributed flow and sediment transport data sets from large rivers in order to support improved parameterizations of sand transport mechanics in morphodynamic models

bifurcation dynamics and avulsion duration in meandering rivers by one dimensional and three dimensional models at river bifurcations water and sediment are divided over two branches the dynamics of the bifurcation determine the long term evolution centuries of the downstream branches potentially leading to avulsion but the dynamics are poorly understood the long term evolution can only be studied by one dimensional models because of computational costs for such models a relation describing the sediment division is necessary but only few relations are available and these remain poorly tested so far we study the division of sediment and the morphodynamics on a timescale of decades to centuries by idealized three dimensional modeling of bifurcations with upstream meanders and dominantly bed load transport an upstream meander favors one bifurcate with more sediment and the other with more water leading to destabilization the bifurcations commonly attain a highly asymmetrical division of discharge and sediment after a few decades to a few centuries depending on combinations of the relevant parameters although past work on avulsions focused on slope advantage we found that bifurcations can be quasibalanced by opposing factors such as a bifurcate connected to the inner bend with a downstream slope advantage nearly balanced bifurcations develop much slower than unbalanced bifurcations which explains the observed variation in avulsion duration in natural systems which branch becomes dominant and the timescale to attain model equilibrium are determined by the length of the downstream bifurcates the radius of the upstream bend a possible gradient advantage for one bifurcate and notably the width depth ratio the latter determines the character of the bars which may result in overdeepening and unstable bars the distance between the beginning of the upstream bend and the bifurcation determines the location of such bars and pools which may switch the dominant bifurcate in fact when the bifurcation is quasibalanced by opposing factors any minor disturbance or a different choice of roughness or sediment transport predictor may switch the dominant bifurcate the division of sediment is nearly the same as the division of flow discharge in most runs until the discharge division becomes very asymmetrical so that a bifurcate does not close off entirely this partly explains the sustained existence of residual channels and existence of anastomosing rivers and the potential for reoccupation of old channel courses we develop a new relation for sediment division at bifurcations in one dimensional models incorporating the effect of meandering the flow and sediment divisions predicted by two existing relations and the new relation for one dimensional models are in qualitative agreement with the three dimensional model these one dimensional relations are however of limited value for wider rivers because they lack the highly three dimensional bar dynamics that may switch the direction of bifurcation evolution the potential effects of bed sediment sorting bank erosion and levee formation on bifurcation stability and avulsion duration are discussed

predicting fractional bed load transport rates application of the wilcock crowe equations to a regulated gravel bed river 1 bed load samples from four locations in the trinity river of northern california are analyzed to evaluate the performance of the wilcock crowe bed load transport equations for predicting fractional bed load transport rates bed surface particles become smaller and the fraction of sand on the bed increases with distance downstream from lewiston dam the dimensionless reference shear stress for the mean bed particle size rm is largest near the dam but varies relatively little between the more downstream locations the relation between rm and the reference shear stresses for other size fractions is constant across all locations total bed load transport rates predicted with the wilcock crowe equations are within a factor of 2 of sampled transport rates for 68 of all samples the wilcock crowe equations nonetheless consistently under predict the transport of particles larger than 128 mm frequently by more than an order of magnitude accurate prediction of the transport rates of the largest particles is important for models in which the evolution of the surface grain size distribution determines subsequent bed load transport rates values of rm estimated from bed load samples are up to 50 larger than those predicted with the wilcock crowe equations and sampled bed load transport approximates equal mobility across a wider range of grain sizes than is implied by the equations modifications to the wilcock crowe equation for determining rm and the hiding function used to scale rm to other grain size fractions are proposed to achieve the best fit to observed bed load transport in the trinity river

effects of shoal margin collapses on the morphodynamics of a sandy estuary shoal margin collapses of several million cubic meters have occurred in the western scheldt estuary the netherlands on average five times a year over the last decades while these collapses involve significant volumes of material their effect on the channel shoal morphology is unknown we hypothesize that collapses dynamicize the channel shoal interactions which could impact the ecological functioning flood safety and navigation in the estuary the objective is to investigate how locations probability type and volume of shoal margin collapse affect the channel shoal dynamics we implemented an empirically validated parameterization for shoal margin collapses and tested its effect on simulated estuary morphological development in a delft3d schematization of the western scheldt three sets of scenarios were analyzed for near field and far field effects on flow pattern and channel shoal morphology 1 an observed shoal margin collapse of 2014 2 initial large collapses on 10 locations and 3 continuous collapses predicted by our novel probabilistic model over a time span of decades results show that a single shoal margin collapse only affects the local dynamics in the longitudinal flow direction and dampen out within a year for typical volumes whereas larger disturbances that reach the seaward or landward sill at tidal channel junctions grow the direction of the strongest tidally averaged flow determined the redistribution of the collapsed sediment we conclude that adding the process of shoal margin collapses increases the channel shoal interactions and that in intensively dredged estuaries shoal margins oversteepen amplifying the number of collapses but because of dredging the natural morphological response is interrupted

optimization of lidar scanning and processing for automated structural evaluation of discontinuities in rockmasses terrestrial light detection and ranging lidar can be used for the delineation and evaluation of geomechanically controlled hazards the united states geological survey 1 has adopted the use of lidar through numerous projects as discussed in 2 other examples of the use of lidar surveys for geological data collection include discussion of the process of acquiring digital outcrop models for stratigraphic modelling 3 mapping basalt flow units 4 structural mapping of a large landslide 5 and evaluation of rockfall source and accumulation zones 6 7 in non geologicalbased applications lidar has been used for projects ranging from volumetric analysis in open pit mines 8 to recording and cataloguing archaeological digs in ancient ruins 9 the equipment mobility accuracy and rate of data collection in comparison to conventional surveying and stereophotogrammetric methods have allowed existing surface analysis projects to proceed at unprecedented levels of detail and have promoted new applications the use of terrestrial ground based lidar as a structural analysis and measurement tool has been investigated in detail by kemeny and post 10 feng and roshoff 11 pringle et al 12 slob et al 13 and others once the data is acquired and the primary 3d model is generated as x y z data points with intensity scalars or mapped colourization via photo coupling the analytical process can proceed in a similar fashion to modern photogrammetric techniques such as those applied by haneberg et al 14 both applications can replace traditional field mapping processes including the use of a compass or inclinometer to measure orientation photos and notebooks to keep records and manual data entry further the conventional measurement of

semi automatic extraction of rock mass structural data from high resolution lidar point clouds abstract in this paper a matlab tool called diana discontinuity analysis for the 2d and 3d geo structural analysis of rock mass discontinuities on high resolution laser scanning data is presented the proposed approach is able to semi automatically retrieve some relevant rock mass parameters namely orientation number of sets spacing frequency and derived rqd persistence block size and scale dependent roughness by analyzing high resolution point clouds acquired from terrestrial or aerial laser scanners in addition with a specific diana option called filterveg we are able to remove vegetation or other disturbing objects from the point cloud which is one of the main problems in lidar data processing some examples of the proposed method have demonstrated its ability to investigate rock masses characterized by irregular block shapes and suggest applications in the field of engineering geology and emergency management when it is often advisable to minimize survey time in dangerous environments and in the same time it is necessary to gather all the required information as fast as possible

automatic characterization of rock mass discontinuities using 3d point clouds abstract direct contact measurements for rock mass discontinuities are generally difficult to perform time consuming biased and often dangerous this paper presents an automatic characterization method for rock mass discontinuities that uses 3d point clouds which can be obtained through non contact measuring techniques such as photogrammetry and light detection and ranging lidar in this method five discontinuity parameters namely the orientation trace spacing roughness and aperture are extracted automatically the overall methodology is as follows 1 orientation is determined by using an improved k means clustering method 2 trace segments are detected by using the normal tensor voting theory and four post processing techniques are employed to compute the trace length 3 spacing is calculated by plotting virtual normal scan lines on the projected traces 4 roughness is evaluated by the correlation between the joint roughness coefficient jrc and the root mean square of the discontinuity surface profile and 5 aperture is obtained by computing the average minimum width based on sub pixel edge detection the proposed method was applied to a drill and blast rock tunnel where the extracted discontinuity parameters were used to calculate the rock mass rating rmr value and geological strength index gsi of the rock mass the application results showed that photogrammetry was more objective and efficient for acquiring rock mass discontinuity information and that it could be used as a potential alternative to the traditional discontinuity mapping method

estimation of rock mass deformation modulus and strength of jointed hard rock masses using the gsi system abstract rock mass characterization is required for many applications in rock engineering practice including excavation design support design stope design amongst others for these purposes it is necessary to obtain design input parameters such as deformation moduli and strength parameters for numerical modeling although such parameters can ultimately be determined from in situ tests at the preliminary design stage where access to underground is limited the practical way to obtain these parameters is to apply a rock mass classification system to characterize the rock mass and estimate the rock mass properties over the years many classification systems such as rqd rock mass rating q and geological strength index gsi systems have been developed amongst them the q system is widely used for rock support system design and the gsi system is used for estimating design parameters the gsi system is the only rock mass classification system that is directly linked to engineering parameters such as mohr coulomb hoek brown strength parameters or rock mass modulus however the application of the existing gsi system is hindered by the facts that the use of the system is to some extent subjective and requires long term experience in the present study a quantitative approach to assist in the use of the gsi system is presented it employs the block volume and a joint condition factor as quantitative characterization factors the approach is built on the linkage between descriptive geological terms and measurable field parameters such as joint spacing and joint roughness the newly developed approach adds quantitative means to facilitate use of the system especially by inexperienced engineers the gsi system is applied to characterize the jointed rock masses at two underground powerhouse cavern sites in japan gsi values are obtained from block volume and joint condition factor which in turn are determined from site construction documents and field mapping data based on gsi values and intact rock strength properties equivalent mohr coulomb strength parameters and elastic modulus of the jointed rock mass are calculated and compared to in situ test results the point estimate method is implemented to approximate the mean and variance of the mechanical properties of the jointed rock masses it is seen that both the means and variances of strength and deformation parameters predicted from the gsi system are in good agreement with field test data

testing bedload transport formulae using morphologic transport estimates and field data lower fraser river british columbia morphologic transport estimates available for a 65 km stretch of fraser river over the period 1952 1999 provide a unique opportunity to evaluate the performance of bedload transport formulae for a large river over decadal time scales formulae tested in this paper include the original and rational versions of the bagnold formula the meyer peter and muller formula and a stream power correlation the generalized approach adopted herein does not account for spatial variability in flow bed structure and channel morphology however river managers and engineers as well as those studying rivers within the context of long term landscape change may find this approach satisfactory as it has minimal data requirements and provides a level of process specification that may be commensurable with longer time scales hydraulic geometry equations for width and depth are defined using morphologic maps based on aerial photography and bathymetric survey data comparison of transport predictions with bedload transport measurements completed at mission indicates that the original bagnold formula most closely approximates the main trends in the field data sensitivity analyses are conducted to evaluate the impact of inaccuracies in input variables width depth slope and grain size on transport predictions the formulae differ in their sensitivity to input variables and between reaches average annual bedload transport predictions for the four formulae show that they vary between each other as well as from the morphologic transport estimates the original bagnold and meyer peter and muller formulae provide the best transport predictions although the former underestimates while the latter overestimates transport rates based on our findings an error margin of up to an order of magnitude can be expected when adopting generalized approaches for the prediction of bedload transport copyright 2005 john wiley sons ltd

the use of a morphological acceleration factor in the simulation of large scale fluvial morphodynamics abstract numerical simulation of fluvial morphodynamic processes can identify important dynamics at time and space scales difficult to observe in the field however simulations involving large spatial scales and or the long timescales characteristic of morphodynamic processes are often untenable because of long computation times the morphological acceleration factor morfac applies a scalar multiplier to the sediment continuity equation and is often applied in morphodynamic simulations to reduce computational time although the use of morfac in coastal simulations is relatively common its applicability in field scale fluvial models is generally confined to steady flow simulations over reach scale spatial domains here we explore the viability of using morfac to simulate large scale long term morphodynamics in a gravel bed river we use delft3d to simulate a 60 d period with a significant discharge event in the nooksack river washington we systematically adjust morfac values ranging from 5 to 50 to compare with a baseline condition of no acceleration model results suggest that morfac based modification of the inflow hydrograph time series reduces peak flow magnitudes and flood wave celerities higher morfac values result in greater flood wave attenuation and lower celerity reducing the simulated morphological impact at locations farther downstream in general relative error compared to the model baseline increases farther downstream because of the altered flood wave propagation however error analysis also shows a positive relationship with channel slope and a negative relationship with channel width hence errors increase in the steeper confined reaches of the upper part of the domain even for the lowest morfac values absolute cumulative volume change errors are on the order of 10 indicating that the use of morfac in fluvial simulations is best restricted to short term and or smaller scale modeling efforts wider channel sections with lower gradients are shown to produce lower morfac related errors therefore morphological acceleration as examined here is potentially more appropriate for limited reaches rather than large scale domains

discontinuity spacing analysis in rock masses using 3d point clouds abstract the complete characterization of rock masses implies the acquisition of information of both the materials which compose the rock mass and the discontinuities which divide the outcrop recent advances in the use of remote sensing techniques such as light detection and ranging lidar allow the accurate and dense acquisition of 3d information that can be used for the characterization of discontinuities this work presents a novel methodology which allows the calculation of the normal spacing of persistent and non persistent discontinuity sets using 3d point cloud datasets considering the three dimensional relationships between clusters this approach requires that the 3d dataset has been previously classified this implies that discontinuity sets are previously extracted every single point is labeled with its corresponding discontinuity set and every exposed planar surface is analytically calculated then for each discontinuity set the method calculates the normal spacing between an exposed plane and its nearest one considering 3d space relationship this link between planes is obtained calculating for every point its nearest point member of the same discontinuity set which provides its nearest plane this allows calculating the normal spacing for every plane finally the normal spacing is calculated as the mean value of all the normal spacings for each discontinuity set the methodology is validated through three cases of study using synthetic data and 3d laser scanning datasets the first case illustrates the fundamentals and the performance of the proposed methodology the second and the third cases of study correspond to two rock slopes for which datasets were acquired using a 3d laser scanner the second case study has shown that results obtained from the traditional and the proposed approaches are reasonably similar nevertheless a discrepancy between both approaches has been found when the exposed planes members of a discontinuity set were hard to identify and when the planes pairing was difficult to establish during the fieldwork campaign the third case study also has evidenced that when the number of identified exposed planes is high the calculated normal spacing using the proposed approach is minor than those using the traditional approach

automated method for extracting and analysing the rock discontinuities from point clouds based on digital surface model of rock mass abstract often when rock discontinuities with complex distributions occur in steep terrain it is difficult to rapidly survey and accurately measure their spatial distribution by traditional surveying and mapping methods this paper presents a methodology for automated extraction of rock discontinuities from a point cloud and the resulting 3d digital surface model of the rock mass first feature planes of rock discontinuities are identified and classified using both their orientation and position in a double nested mean shift clustering algorithm second the points corresponding to feature planes are extracted using a region growth algorithm and seed points finally geological information is acquired by analysing the geometric features of the extracted sub set of points from the point cloud this approach can directly extract planar features associated with joints and it eliminates spurious points in a point cloud associated with objected such as vegetation a case study of a rock slope along a highway is presented using the proposed method a sensitivity analysis of relevant clustering parameters in the mean shift clustering algorithm is conducted to acquire their optimal values and to assess their robustness the proposed method produces results that agree with the traditional survey methods and greatly improves the survey efficiency