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Goodman, R. E.

Publications and source records attributed to Goodman, R. E..

17 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1971

Borehole probes: Summary of previous work

Previous research explored the applicability of some devices to lunar borehold testing and, in particular, examined the use of such instruments to assess the strength of soils and rocks. Special attention was given to borehole jacks, which essentially conduct a plate bearing test across opposing wall areas. Analytical work employed finite element analysis, the theory of plasticity, and the theory of elasticity using the complex variable method. A number of solutions were reached for tractable subproblems in the set of problems posed when a jack is used to expand sectors of a borehole. In addition, an investigation with physical models was made to explore the modes of behavior for varying boundary conditions and materials, including both elastic and plastic media.

Goodman, R. E.↗
NASA NTRS1971

An experimental study of the mechanism of failure of rocks under borehole jack loading

Laboratory and field tests with an experimental jack and an NX-borehole jack are reported. The following conclusions were made: Under borehole jack loading, a circular opening in a brittle solid fails by tensile fracturing when the bearing plate width is not too small. Two proposed contact stress distributions can explain the mechanism of tensile fracturing. The contact stress distribution factor is a material property which can be determined experimentally. The borehole tensile strength is larger than the rupture flexural strength. Knowing the magnitude and orientation of the in situ stress field, borehole jack test results can be used to determine the borehole tensile strength. Knowing the orientation of the in situ stress field and the flexural strength of the rock substance, the magnitude of the in situ stress components can be calculated. The detection of very small cracks is essential for the accurate determination of the failure loads which are used in the calculation of strengths and stress components.

Van, T. K.↗
NASA NTRS1971

A borehole jack for deformability, strength, and stress measurements in a 2-inch borehole

A borehole jack devised for lunar exploration is described and results of its use in simulated lunar solids are presented. A hydraulic cylinder mounted between two stiff plates acts to spread the plates apart against the borehole walls when pressured. The spreading is measured by a displacement transducer and the load is measured hydraulically. The main improvement over previous instruments is the increased stroke, which allows large deformations of the borehole. Twenty-eight pistons are used to obtain a high hydraulic efficiency, and three return pistons are also provided. Pressure-deformation curves were obtained for each test on Lunar Soil Simulant No. 2, a light gray silty basalt powder.

Goodman, R. E.↗
NASA NTRS1971

Lunar surface engineering properties experiment definition

Research on the mechanics of lunar soils and on developing probes to determine the properties of lunar surface materials is summarized. The areas of investigation include the following: soil simulation, soil property determination using an impact penetrometer, soil stabilization using urethane foam or phenolic resin, effects of rolling boulders down lunar slopes, design of borehole jack and its use in determining failure mechanisms and properties of rocks, and development of a permeability probe for measuring fluid flow through porous lunar surface materials.

Mitchell, J. K.↗