Leslie Sour Gertsch

Use of TBM muck as construction material

Abstract Tunnel boring machines (TBMis) are widely used in tunnel construction in rock. The rock chips (muck) produced are rarely used for construction applications, however, because the suitability of the material is not well understood. Yet the cuttings appear to be of approximately the correct average size for some applications. If they are suitable in other respects, cost savings can be realized in tunnel construction, where aggregate is a common requirement. A review of standard construction aggregate specifications indicates that hardrock TBM much would be suitable for several construction applications with a minimum of processing: road pavement and structural concrete. Processing options also are discussed for cases where the raw TBM muck is nearly, but not quite, suitable. A 0.65 metric ton (1420 lb) cutting sample generated by a laboratory tunnel boring machine operating in a welded tuff is analyzed for suitability for different construction applications. In addition, numerous tunneling projects that use or have studied TBM waste for construction purposes are described.

Near-earth Resources

ABSTRACT: The technologies required to detect, track, categorize, and intercept objects in Earth‐impacting orbits can also provide access to their rich storehouse of materials. Mitigation of a clear and present near‐Earth object (NEO) threat to the Earth must provide the greatest assurance of success with the least risk to the planet. In some cases, mining a threatening NEO may become a viable alternative or supplement to a deflection or interception scenario. This converts the NEO threat to a near‐Earth resource. NEOs can supply materials for a wide range of operations both in space and on Earth, as they are thought to contain large amounts of water, carbon, structural metals, industrial feedstocks of many types, and precious metals. This wealth has low overhead for utilization in space; some known NEOs would require lower transportation energy expenditure than lunar resources. Mining a NEO inherently requires, among other things, altering the mass distribution of the body during exposure, removal, and processing of the ore. These processes can be tailored to facilitate deflection of the body from Earth impact by altering its orbital characteristics. The advantage of NEO mining is that it can mitigate the threat — the primary effort — while converting it into resources for space exploration. This additional effort, within an appropriate time scale, allows sequential mitigation of the NEO in a controlled manner while providing the resources contained within the NEO for use either in space or on Earth. Both goals, to be successful, will require maximum utilization of all sources of knowledge. The two most important are an extensive reconnaissance of the target NEO and the long history of terrestrial mining practice. This paper discusses how current mining technology might be adapted to mine NEOs, whether threatening or not. It summarizes our knowledge of NEO composition, physical properties, and mining and processing methods, and points out areas where further research, especially physical testing in space, is vital. The great potential of NEO resources and the successful mitigation of NEO threats will be best realized if their utilization is considered from the earliest planning of Earth‐NEO mitigations.

Excavation of Lunar Regolith with Large Grains by Rippers for Improved Excavation Efficiency

AbstractAs human activities expand to the Moon, Mars, and other extraterrestrial bodies, it will be necessary to use local resources rather than bringing everything from Earth. In situ resource utilization (ISRU), or planetary surface engineering, starts with excavation and dirt-moving. The current study focuses on excavation of lunar regolith simulant by blading with and without preripping (mechanical raking) and points out the need for considering the relative proportion of coarse grains in regolith when dealing with excavation force and energy. The coarse-grain content of the lunar regolith, estimated from 11 Apollo cores, can reach 30% by mass. Prior ripping of vibrationally compacted beds of a standard fine regolith simulant can decrease total excavation resistance (when subsequent blading is included) by up to 20% for relative regolith densities greater than 60%. The effect of coarse grains on the response of compacted regolith to excavation was more significant than would be expected in most terres...

Mining Near‐Earth Resources

ABSTRACT: Mining the potentially vast storehouse of natural resources contained within near‐Earth objects (NEOs) could assist mitigation of the danger that a threatening object presents to life on Earth. Properly planned, NEO mining could provide a substantial basis for the exploration and development of space, in addition to providing important tools and opportunities for mitigating impact hazards.

Effect of Regolith Compaction on Ripping Efficiency

Lunar regolith is known to be surprisingly stiff compared to terrestrial soils because of its angular grain shape, very small grain size, and high relative density. One of the ways to reduce the excavation force and energy is to loosen the soil prior to excavation. In experiments using JSC-1A lunar regolith simulant at three different compaction levels, ripping of the simulant was followed by pushing a wide blade though it. The energy required to move the ripper and the wide blade was measured and analyzed to determine how the excavation energy is affected by the density of simulant, as well as the number and position of tines on the ripper. It was found that ripping increases the efficiency of excavation of lunar regolith denser than 60% relative density. The optimal spacing of tines in this simulant is about 25mm (1.0inch), which agrees with the condition that the failure zones formed by neighboring tines just touch each other.

A Phased Array Approach to Rock Blasting

A series of laboratory-scale simultaneous two-hole shots was performed in a rock simulant (mortar) to record the shock wave interference patterns produced in the material. The purpose of the project as a whole was to evaluate the usefulness of phased array techniques of blast design, using new high-precision delay technology. Despite high-speed photography, however, we were unable to detect the passage of the shock waves through the samples to determine how well they matched the expected interaction geometry. The follow-up mine-scale tests were therefore not conducted. Nevertheless, pattern analysis of the vectors that would be formed by positive interference of the shockwaves from multiple charges in an ideal continuous, homogeneous, isotropic medium indicate the potential for powerful control of blast design, given precise characterization of the target rock mass.

Total Ore Processing Integration and Management

A new dataset to illustrate ordinary, non-segregated operation of the mine and mill has been collected. Beginning in mid-November, it ended on 31 December, 2004. Drill monitoring data for several blast patterns is being analyzed. Figures 1 through 6 represent one of the patterns. Sample preparation for laboratory rock strength tests is underway, for comparison with the density and point-load test results measured last summer. The relationships among data mined from the databases and the ore segregation tests of both mines are being examined, mainly through use of multiple regression analysis. The study is ongoing.