Quarry Blasts Research Articles

The investigation of toppling slope failures in welded ash flow tuff at Glennies Creek Dam, New South Wales

The Glennies Creek Dam spillway was designed as an unlined rock cutting in welded tuff 700 m long with a bedwidth of 37 m, a maximum cut height of 40 m and right-and left-hand side slopes of 3 in 1 and 2 in 1, respectively. Toppling failures in the 3 in 1 right-hand spillway batter occurred during construction. In order to maintain rockfill production, that part of the right-hand batter affected by the failures was battered back from 3 in 1 to a slope of 1 in 1; involving 33 000 m 3 of additional excavation. Geological investigations concluded that toppling became possible due to the removal of the column toe support due to plane sliding movements on joints dipping towards the cut at 24°. These sliding movements were caused by immediately adjacent heavy quarry blasting which reduced the available joint friction angle from the peak value of 38° to the residual value of 25°. An essential step in the analysis of slope stability is the identification of slopes susceptible to toppling. The application of standard methods of toppling analysis to slopes which are not susceptible to toppling even though it may be kinematically possible will result in unnecessarily conservative slope designs.

Seismic control of mine and quarry blasting in the USSR : Fadeev, A B; Glosman, L M; Kartuzov, M I; Safonov, L V Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug–10 Sept 1987V1, P617–619. Publ Rotterdam: A A Balkema, 1987

Seismic control of mine and quarry blasting in the USSR : Fadeev, A B; Glosman, L M; Kartuzov, M I; Safonov, L V Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug–10 Sept 1987V1, P617–619. Publ Rotterdam: A A Balkema, 1987

Road Building and the Survival of Indigenous Forest in the Southern Cape

SYNOPSIS The effects of road building activities on indigenous evergreen forest were investigated to quantify the impact, to provide guide-lines for minimising damage to forests during future road projects and to gain understanding of the response of different species. The investigation centred on the new Tsitsikamma Toll Road through the Platbos indigenous forest. In relation to total forest area cleared for the road, short-term mortality in the remaining forest, resulting from ponding, sedimentation and soil compaction, was minimal. Tree mortality was caused by ponding and sedimentation owing to insufficient drainage, by soil topping from fills and topsoil addition for revegetation of road verges, by soil compaction from temporary service roads and storage of equipment and materials underneath the trees and by rock blasting in quarries. Exposure of the new forest edge by clearance had very little detrimental effect on the trees. Species differed in their response. This could be related to their ecological requirements. Potential changes in species composition are discussed. The dangers posed by invader plants are indicated. Recommendations for limitation or prevention of damage to the forest or trees are made for inclusion as conditions during future road building contracts. The guide-lines are also applicable to logging of timber and management of recreation sites in the forest.

Crustal parameters in the Iberian Peninsula

The structure of the crust in the Iberian Peninsula has been investigated for the last 15 years by Spanish and Portuguese groups in close collaboration with other European institutions. The first experiments were carried out in Portugal (Mueller et al., 1973) with the aim of investigating the crustal structure of the Hercynian belt in the southwest corner of the Iberian peninsula. Other experiments have been subsequently realized to study different aspects of the crust in various regions of Portugal. In Spain the main effort has been focused in Alpine areas, with the first experiments in the Alboran Sea and the Betic Cordilleras (Working Group for Deep Seismic Sounding in Spain, 1974–1975, 1977; Working Group for Deep Seismic Sounding in the Alboran Sea, 1974–1975, 1978). Follow-up experiments until 1981 completed the work in the Betic Cordillera. Extensive experiments were carried out in the Pyrenees in 1978. Further surveys covered the Balearic Islands in 1976, the Valencia Trough in 1976 and 1983, and the Celtiberian Chain (or Iberic system) in 1981. The Hercynian belt has only been studied in detail in the northwest corner of Spain in 1982, with smaller studies in the central Iberian Massif in 1976 and 1986. Mostaanpour (1984) has compiled some crustal parameters (crustal thickness, average crustal velocity and Pn velocity) for western Europe. Meanwhile, more complete data are available for the Iberian Peninsula. The results presented here were derived from a large number of seismic refraction experiments which have been carried out mostly along or close to coastal areas of the Iberian Peninsula. Offshore explosions of various sizes were used as the energy source in most cases, in addition to some quarry blasts. Unfortunately this leaves most of the inner part of the Iberian Peninsula unsurveyed. Our purpose is to summarize some of the crustal parameters obtained so far and to detail the appropriate literature for the interested reader.

Seismotectonics of the Newport-Inglewood fault zone in the Los Angeles basin, southern California

AbstractThe Newport-Inglewood fault zone (NIF) strikes northwest along the western margin of the Los Angeles basin in southern California. The seismicity (1973 to 1985) of ML ≧ 2.5 that occurred within a 20-km-wide rectangle centered on the NIF extending from the Santa Monica fault in the north to Newport Beach in the south is analyzed. A simultaneous full inversion scheme (VELEST) is used to invert for hypocentral parameters, two velocity models, and a set of station delays. Arrival time data from three quarry blasts are included to stabilize the inversion. The first velocity model applies to stations located along the rim and outside the Los Angeles basin and is well resolved. It is almost identical to the starting model, which is the model routinely used by the CIT/USGS southern California seismic network for locating local earthquakes. The second velocity model applies to stations located within the Los Angeles basin. It shows significantly lower velocities down to depths of 12 to 16 km, which is consistent with basement of Catalina Schist below the sediments in the western Los Angeles basin. The distribution of relocated hypocenters shows an improved correspondence to mapped surface traces of late Quaternary fault segments of the NIF. A diffuse trend of seismicity is observed along the Inglewood fault from the Dominguez Hills, across the Baldwin Hills to the Santa Monica fault in the north. The seismicity adjacent to Long Beach, however, is offset 4 to 5 km to the east, near the trace of the subsurface Los Alamitos fault. The depth distribution of earthquakes along the NIF shows clustering from 6 to 11 km depth, which is similar to average seismogenic depths in southern California. Thirty-nine single-event focal mechanisms of small earthquakes (1977 to 1985) show mostly strike-slip faulting with some reverse faulting along the north segment (north of Dominguez Hills) and some normal faulting along the south segment (south of Dominguez Hills to Newport Beach). The results of an inversion of the focal mechanism data for orientations of the principal stress axes and their relative magnitudes indicate that the minimum principal stress is vertical along the north segment while the intermediate stress is vertical along the south segment. The maximum principal stress axis is oriented 10° to 25° east of north. Reverse faulting along the north segment indicates that a transition zone of mostly compressive deformation exists between the Los Angeles block and the Central Transverse Ranges.

Effects of discontinuities on fragmentation by blasting

Abstract The blasting operation in discontinuous rock requires the investigation of the inter-relationship between joint orientation and position of blasting boreholes. The basic laws of fragmentation of rock were evaluated. Sizes and shapes of the fragmented volumes with various degrees of fissuratlon were determined. Method of simulation was used in comminution experiments for optimizing blasting in quarries. The crushibility index has been used to characterize the fragmentation. A series of experiments has been completed in a quarry. The size distribution parameters are essential to economical and efficient hauling and crushing.

Velocity structure and aftershock distribution of the 1982 Urakawa-Oki Earthquake.

Aftershock distribution of the Urakawa-oki earthquake (Ms 6.8) of 1982 is investigated. A simultaneous inverse method is applied to P-wave arrival time data from the aftershocks and quarry blasts in order to estimate a three-dimensional velocity structure in the aftershock region. Strong correlations between the obtained velocity structure, geology, and gravity anomalies are observed. Hypocentral determination of the aftershocks by using the three-dimensional velocity structure shows that the epicentral distribution is a triangle and its area is 790 km2. The detailed aftershock distribution indicates that three dipping planes with high aftershock activities appeared in the aftershock region: two of the planes are almost parallel to each other with a dip angle of 50°in a depth range of 3 km to 27 km, and these planes clearly form double aftershock planes, which have been previously supposed to be an identical plane; the other plane is located perpendicularly to the double aftershock planes in a depth range of 13 km to 27 km and seems to be a conjugate plane with the double aftershock planes. The aftershocks occur in a region with P-wave velocities higher than 5 km/s, and the conjugate plane is located along the structural boundary. It is found that the rupture of the main shock took place on the conjugate plane and also might have been caused by a tectonic force derived from a collision between the Kurile and Northern Honshu Japan Arcs.

Detailed S-wave structure in the Dublin Basin and its northern margin

Summary. The seismic structure has been measured to a depth of about 3 km along a 30 km seismic profile in east central Ireland. This profile is unusual in that it is the S-wave velocity—depth structure that has been measured to a degree of precision more normally associated with P-wave results. One reason for this is that the sources used were quarry blasts which generated strong S-waves and short-period surface waves but rather weak P-waves. The results show a layer of Carboniferous limestone with shear velocity 2.65 km−1 s overlying a layer with a velocity of 3.06 km s−1. This second layer was interpreted as Lower Palaeozoic strata (Silurian/Ordovician) since this velocity was evident in an inlier seen at the surface at the northern end of the line. A third refraction horizon, shear velocity 3.45 km s−1 and displaying a basinal structure, was also recognized. This may be Cambrian or Precambrian basement.

Microcomputer based seismic instrumentation systems

Summary Developments in microprocessor technology are having considerable influence on the way engineering seismic data is collected, processed and analysed. Case studies of two seismic instrumentation systems and their applications are described. A microcomputer enhanced engineering seismograph, Geoseis-Merlin, has been developed as a portable repackaged Apple unit with a 5 inch monitor, internal printer, bubble memory and disk drive to give on-site processing and results. The unit includes a multi-channel, 12 bit analogue to digital converter card with programmable gain amplifiers, and the system is designed to operate in the field as a self-contained, six channel, seismic processing system. Menu-driven software operations include: data capture incorporating a pre-trigger memory facility for blast monitoring, concatenation and editing of files, display of seismic time data, seismic refraction analysis of up to 24 channels, power spectral computation, display of power and attenuation spectra, spectral smoothing, and digital filtering of waveforms. The system can also be used as an interface to existing seismographs or to the radio telemetric seismic monitoring system. A 24 channel, radio telemetric, seismic monitoring system has been developed, consisting of six portable outstations which can be positioned up to 2 km from a base station located in a Land Rover or site office. Each microcomputer controlled outstation has one air overpressure and three ground vibration channels for recording up to 16 sec of pre-and post-trigger data. Communication between each outstation recorder and base is via a UHF duplex telemetry link which is used to activate and program each outstation, to maintain synchronization and to transfer data from each recorder to the microcomputer controlled base station. Here the captured seismic event can be stored on cassette, displayed on a 5 inch monitor, or transferred to an Apple II microcomputer (Geoseis-Merlin) for processing. The case studies outline the application of these systems in engineering geology to bedrock depth determination, rock mass characterization, and the monitoring of quarry blasting.

Crustal Structure Along the Ramapo Fault Zone, New York State

One- and three-dimensional models of crustal structure in the vicinity of the Ramapo fault zone are derived from P-wave arrival time data. We supplement earthquake and quarry blast arrivals recorded by regional network stations with data recorded by portable seismic instruments at former network sites. The portable array data provide a critical link between data recorded on the current and former network alignments. Station corrections derived along with the one-dimensional crustal model and the three-dimensional model both indicate significant lateral velocity variations, in the range of 10 to 15 per cent, across the Ramapo fault in southeastern New York.

Deep seismic sounding using quarry blasts as the source of seismic energy

Deep seismic sounding using quarry blasts as the source of seismic energy

Constraints on lateral variation in upper crustal structure beneath southern New England from dispersion of Rg waves

Group velocity dispersion was determined for Rayleigh waves between periods of 0.5 and 2.0 sec (Rg) recorded from quarry blasts in southern New England. The paths of these surface waves traverse various geologic structures, and distinct dispersion regions have been identified. Normal dispersion was consistently observed in the period range studied, indicating a superficial layer of relatively low velocity (4.1<Vp<5.5) at least 1 km thick in the upper crust throughout this region. Seismic velocity in this upper layer varies laterally and correlates, to some extent, with geologic features. The observed dispersion also indicates that seismic velocity at depths of 5 to 10 km beneath southern New England varies laterally.

A seismic refraction study of the crustal structure associated with the Adamawa Plateau and Garoua Rift, Cameroon, West Africa

Summary Recordings of quarry blasts along a 300 km profile across the Adamawa Plateau at the eastern end of the Cameroon Volcanic Line permitted the determination of the crustal structure of the region. To the north of the Plateau in the area of the Garoua Rift, an eastern arm of Benue Trough the crust is about 23 km thick and is underlain by upper mantle with a P-wave velocity of 7.8 kms-1. The southern part of the Plateau by comparison is associated with a more normal crustal thickness of about 33 km and underlain by upper mantle with a velocity of 8.0 kms-1. Between these two areas the seismological experiment was not able to delineate how the crust changes. However, if the topography and gravity field reflect crustal thickness then there is a rapid change in crustal thickness at the northern edge of the Adamawa Plateau. The study thus provides the first seismic evidence for major crustal thinning beneath the Garoua arm of the West African Rift System as well as providing evidence for an alternative model for the formation of the Cameroon Volcanic Line.

An investigation of the crustal structure of north-west England using quarry blasts as seismic sources

SUMMARY Seismic refraction profiles have been established between quarries at Outscar and Oddendale (on the north-eastern margin of the Lake District), Holmepark (between Lancaster and Kendal), and Arcow (Ribblesdale). The profile between Outscar and Holmepark traverses the Shap granite intrusion and outcrops of Silurian meta-sedimentary rocks. The eastern line crosses the Ingleton Coal Measures basin and continues onto the Askrigg Block, where the basement is formed of Lower Ordovician (Ingletonian) metamorphic rocks. The P wave velocity, S wave velocity, and Poisson’s ratio of the Carboniferous Limestone were estimated to be 5.250 km s −1 , 2.854 km s −1 , and 0.290 respectively. The corrresponding values for Silurian rocks were 5.635 km s −1 , 3.144 km s −1 ,0.274, and for Lower Ordovician metamorphic rocks on the Askrigg block were 5.984 km s −1 , 3.326 km s −1 , and 0.276. In addition, at the longer ranges, arrivals with a P velocity of 6.25 ± 0.15 km s −1 were detected on both the profiles. Seismic models derived by ray tracing are compatible with the view that the pre-Silurian basement between the Lake District and the Askrigg block is of Lower Ordovician age, equivalent to the Ingletonian rocks on the block, and that it extends westwards to the point at which it is intruded by the granite batholith that underlies the Lake District.

P-wave travel-time residuals in the Newfoundland Appalachians

Teleseisms and quarry blasts were recorded at 24 temporary seismograph sites along a line across the northern Dunnage Zone of Newfoundland. Azimuthally dependent functions were also determined for teleseismic P-wave travel-time residuals at the permanent St. John's (STJ) and Corner Brook (CBK) seismographs. In order to minimize the effects of reading errors and structure far from the receivers, absolute residuals at the field sites were then obtained by correlating the records with those from STJ and CBK and using the residual functions for these two stations. The P-wave residuals in north-central Newfoundland tend to be up to half a second later than at STJ and CBK, with the more positive values towards the east of the region. The direction of fastest approach for rays varies from southeast at STJ to southwest towards the western side of the Dunnage Zone. The travel-time residuals are generally similar to variations observed elsewhere in the Appalachians.The residuals and gravity data indicate that the crust is about 40 km thick over most of the Dunnage Zone, possibly increasing by several kilometres under the Gander Zone and western Avalon Platform, which could be consistent with a former subduction zone in the region. The low crustal velocity of 6.2 km s−1 may support an allochthonous model for central Newfoundland, with average crustal thickening of about 10 km compared with adjacent platform areas.

Wide Angle Reflection Study of Crustal Structure, Eastern Pennsylvania - Northern New Jersey

A 12 channel, digitally recorded wide-angle reflection profile was conducted in the northeast trending Great Valley of eastern Pennsylvania-northern New Jersey. The wide-angle reflections were inverted to determine the crustal velocity structure of the region:, Specifically, the experiment was designed to determine if the Conrad discontinuity existed in eastern PA - northern NJ and to determine its depth and the thickness of the crust. Six quarry blasts, timed by a geophone located at the quarry, were recorded at three offsets of 73.8 km, 118.3 km, and 146.7 km. The common-receiver array was located at an abandoned railroad track parallel to Paulinskill Lake, Sussex, County, New Jersey. It consisted of 11 geophone groups spaced 213 meters apart. Since the reduced data contained a low S/N ratio for which the computer was unable to pick the P-arrivals, the data were treated subjectively for the sweep of the P-wave arrival across the array at the expected time. The travel time and normal moveout were then calculated for coherent phase signals across the traces. These data were plotted on a t(p) (intercept time-ray parameter) section and best-fit by hand with two elliptical curves. A cusp in the data suggests a 2 layer structure with a velocity discontinuity at 29 km. The upper layer has a near surface compressional wave velocity of 5.8 km. The lower layer is 17 km thick with a velocity of 7.7 km. This velocity transition suggests that the Conrad discontinuity has been observed in the study area.

DEEP STRUCTURE AND ORIGIN OF THE NORTHUMBERLAND AND STAINMORE TROUGHS

SUMMARY The Lower Carboniferous trough and block structures of northern England were discovered and delineated by geological and gravity observations. New information on the depth to the underlying basement comes from seismic refraction studies using quarry blasts, and from observations of the LISPB shots of 1974 along a north-south line of temporary stations from the Northumberland Trough to the Craven Basin (the NERL line). In agreement with earlier gravity interpretations, this new seismic evidence shows that the Northumberland Trough is about 3–4 km deep beneath north-eastern England, and that the Stainmore Trough is about 2.5 km deep across the Pennines. Seismic data from NERL and from the Rookhope array station indicate a 6.5 km s −1 layer at about 12 km depth and the Moho at about 28 km depth. To within the accuracy attained, the Moho appears to be at the same depth beneath both blocks and troughs. The regional and differential subsidence are both primarily attributed to stretching of the lithosphere (including crust) in a north-south direction. The lithospheric tension was probably mainly caused by the slabpull force (or trench suction?) resulting from subduction of the attached oceanic part of the plate which formed the closing Hercynian marginal sea to the south, supplemented in the continental crust by tension related to the crustal thickness. It is suggested that the ductile lower part of the lithosphere, including the lower continental crust, was stretched to a much greater extent than the strong and brittle uppermost layer as a result of resistance to subduction at shallow depth. The regional subsidence was partly the isostatic response to thinning of the lower ductile part of the continental crust; subordinate thermal subsidence probably contributed, but this was cut short by a new thermal event at the end of the Carboniferous. Differential subsidence is attributed to faulting in the upper continental crust in response to the tension. This allowed the buoyant granites to remain relatively stable as the intervening regions subsided, with the Moho shallowing regionally but not developing strong local variations in depth.

Dynamic waveform matching

Dynamic waveform matching (DWM) is a generalization of cross correlation that is useful in waveform classification and feature extraction problems. While cross correlation matches two signals by shifting the time axis of one signal relative to the other, DWM matches signals by shifting and warping the time axis until the corresponding features of the two waveforms are properly aligned. The optimum shift and warping of the time axis is determined by dynamic programming. The dynamic programming algorithm behind DWM can be used in many matching applications. Several geophysical applications of DWM are described. These include identifying local earthquake arrival times, extracting features useful for discriminating between earthquakes and underground nuclear explosions, waveform clustering, identifying quarry blasts, interpreting full wave acoustic well logs, well to well correlation, and matching P-wave reflection profiles to S-wave reflection profiles. The similarity between DWM and error correcting regular grammars can be used to add grammarlike capabilities to the matching algorithm.

Inhomogeneous structure of the Voronezh shield lithosphere from explosion seismology data

This paper presents the results of a seismological investigation of the Voronezh shield. The use of industrial quarry blasts, as the most economic seismic energy source, and telemetric arrays of the Taiga type for deep seismic sounding observations has enabled the Geophysical Research Group of the Voronezh State University to obtain complete and valid information concerning the deep structure of the shield. Seismic records of refracted and reflected P and S phases from the intracrustal and subcrustal discontinuities allow the determination of independent and compatible velocity models V P( Z) and V S( Z). Analysis of the travel-time and amplitude curves derived from the deep seismic sounding data reveals a complex and inhomogeneous structure of the Voronezh shield lithosphere. The major discontinuities are found in the middle part of the consolidated crust. Several rather thick layers can be resolved, which are separated by first-order seismic boundaries. In the consolidated crust beneath the southeastern part of the shield at depths from 6–7 to 11–13 km, a low-velocity layer is clearly established from the compressional wave data. Within the low-velocity channel, V P appears to decrease by 5–6%. The low-velocity channel in the uppermost consolidated crust is assumed to be due to metamorphogeneous granitization. This is revealed by the Precambrian basement structure. Poisson's ratio calculated from the compatible velocity models V P( Z) and V S( Z) shows a systematic increase down to the crustal basement and becomes discontinuous only in the low-velocity channel. At the top of the mantle, Poisson's ratio decreases on all the deep seismic sounding profiles. The systematic variation of Poisson's ratio is related to changes in the composition and mineralogy of the Voronezh shield lithosphere.

砕石爆破に伴う地電位の変化

We observed self-potential variations associated with quarry blasts. The amplitude of the observed self-potential across a pair of electrodes 20 to 50m apart is about 5-20mV in the distance range of 5-100m from the blast point. The variation of the self-potential began before the elastic wave arrival to the electrodes, and seem to have begun almost simultaneously with the rock blast. Later parts of the self-potential signals are very similar to those of the transverse components of seismic signals and indicate that the electric potential variation is induced by seismic-wave propagation, probably due to the electro-kinetic phenomena proposed by MIZUTANI et al. (1976), and experimentally studied by PARKHOMENKO (1964).The cause of the earliest part of the self-potential variation is unknown. Since the present quarry blast is for shale and the site is highly wet, it is very unlikely for the piezo-electric effect to have caused such a large variation of electric potential field. The self-potential variation might be related to the phenomena such as tribo-electricity or charge separation on newly-created surfrces.If the occurrence of self-potential variation associated with the present quarry blasts is generally true for any type of rock failure, the measurement of self-potentials on ground may yield a new tool for exploring a physical mechanism of natural earthquakes, as well as for determining the origin time of the earthquakes. Further field measurement and laboratory experiments are required to reveal the nature of the self-potential variation associated with rock failure.