Analysis of Lunar Boulder Tracks: Implications for Trafficability of Pyroclastic Deposits

In a new era of lunar exploration, pyroclastic deposits have been identified as valuable targets for resource utilization and scientific inquiry. Little is understood about the geomechanical properties and the trafficability of the surface material in these areas, which is essential for successful mission planning and execution. Past incidents with rovers highlight the importance of reliable information about surface properties for future, particularly robotic, lunar mission concepts. Characteristics of 149 boulder tracks are measured in Lunar Reconnaissance Orbiter Narrow Angle Camera images and used to derive the bearing capacity of pyroclastic deposits and, for comparison, mare and highland regions from the surface down to ~5‐m depth, as a measure of trafficability. Results are compared and complemented with bearing capacity values calculated from physical property data collected in situ during Apollo, Surveyor, and Lunokhod missions. Qualitative observations of tracks show no region‐dependent differences, further suggesting similar geomechanical properties in the regions. Generally, bearing capacity increases with depth and decreases with higher slope gradients, independent of the type of region. At depths of 0.19 to 5 m, pyroclastic materials have bearing capacities equal or higher than those of mare and highland material and, thus, may be equally trafficable at surface level. Calculated bearing capacities based on orbital observations are consistent with values derived using in situ data. Bearing capacity values are used to estimate wheel sinkage of rover concepts in pyroclastic deposits. This study's findings can be used in the context of traverse planning, rover design, and in situ extraction of lunar resources

Footwear and soft ground interaction

The aim of the research reported in this thesis was to improve the understanding of footwear and soft ground interaction and, in particular, its mathematical modelling.The work was undertaken for the Military Footwear Section of the MOD's Defence Clothing and Textiles Agency (DCTA) who funded the research in conjunction with the Engineering and Physical Sciences Research Council (EPSERC). Although research has been carried out on the interaction of footwear on firm surfaces, minimal work has previously been carried out on softer surfaces often encountered in combat situations and little effort has been applied to its mathematical modelling. The researchprogramme included the development of mathematical models using soil mechanics theory, and experimental work using a soft-ground slip-rig.The prototype soft-ground footwear slip-rig that has been developed is a manually operated device based on simple mechanical mechanisms using weights and pulleys. The rig enables the measurement of traction and sinkage for different soil types, sole materials and tread geometry, at various angles of heel contact and applied verticalload. All experimental work has been carried out with the use of scaled up cleats to obtain measurable results.An investigation into three dimensional end effects has determined at what cleat length the problem becomes two dimensional. The experimental results have shown theeffects of cleat geometry on total cleat traction for sand, and in particular the geometric characteristics that promote and reduce traction. These results have been analysed using Taguchi's Analysis of Variance technique. Traction distribution experiments have determined the proportion of traction obtained from different cleat areas.Soil mechanics theory, and in particular Coulomb's retaining wall theory, has been applied in the theoretical modelling of footwear and soft ground interaction. A twodimensional total traction model has been developed using MATLAB software and experimental and theoretical results have been compared. The traction versus cleat geometry trends for both the experimental and theoretical results were in good agreement

Lunar soil mechanics, 1966-1967

Soil engineering problems, techniques, and research program studied for application in lunar exploratio

Mechanical and hydraulic long-term behavior for an experimental compacted liner embankment

Mechanical and hydraulic performance, as compaction, consolidation, and permeability, play an important role in the design and construction of earthworks. A bad dimensioning of this magnitude can lead to major disasters, making structures unfeasible, losing resources and even lives. This work looks to correlate quick tests of soil mechanics with parameters that are difficult to obtain - in situ and laboratory tests -, either because of lack of resources or the access in some unexplored areas. An experimental embankment located in Penalobo, Guarda (Portugal) was chosen to perform in situ tests and sampling for laboratorial tests. The tests for geotechnical characterization – specific gravity, Atterberg limits, particle size distribution, Normal Proctor compaction, soil density gauge, and gamma densimeter -, mechanical behavior – free expansibility, one-dimensional oedometric consolidation, consolidated undrained triaxial shearing, plate load test, dynamic penetration lightweight, and heavyweight, and cone penetration test -, chemical composition – x-ray diffractures, fluorescence, scanning energy microscopic images, cation exchange capacity, and pH -, and hydraulic conductivity through falling head permeameter permitted to correlate several parameters. Results characterize the soil as a typical granitic soil, a well-graded sand without plasticity classified as A-1-b according to AASHTO, specific gravity of 2.55, with optimal compaction following w = 14.0% and ?d = 1.86 g/cm3 . Mainly composed by quartz, kaolinite, and muscovite, along with high amounts of SiO2 and Al2O3, besides lower percentages of NaO2 and Fe2O3, also showed pH = 6.0 and cation exchange capacity = 17.0 meq/100g. The soil has high free expansibility, although low oedometric compressibility when compacted, effective internal friction angle is around 35º and has no cohesion. Several rounds of tests were made for this evaluation, and since the site is studied for over ten years, another analysis on behalf of long-term behavior of the structure was carried out. Long-term behavior analysis and parameters correlations were developed around compaction characteristics within Normal Proctor, soil density gauge and gammadensimeter results; direct and indirect hydraulic conductivity through oedometer and permeameter laboratorial tests; drilling tests relationship among dynamic penetration lightweight, and heavyweight, standard penetration test, and cone penetration tests; in addition to laboratorial oedometer and in-situ plate load test analysis the consolidation of the embankment liner.Desempenho mecânico e hidráulico, como compactação, consolidação e permeabilidade, desempenham um papel importante no projeto e construção de terraplenagem. Um mau dimensionamento dessa magnitude pode levar a grandes desastres, inviabilizando estruturas, perdendo recursos e até mesmo vidas. Este trabalho procura correlacionar testes rápidos de mecânica dos solos com parâmetros de difícil obtenção - in loco e de laboratório -, seja por falta de recursos ou pelo acesso em algumas áreas inexploradas. Um aterro experimental localizado em Penalobo, Guarda (Portugal) foi escolhido para a realização de ensaios in situ e amostragem para ensaios laboratoriais. Os ensaios de caracterização geotécnica – gravidade específica, limites de Atterberg, distribuição granulométrica, compactação Normal Proctor, medidor de densidade do solo e densímetro gama -, comportamento mecânico – expansibilidade livre, consolidação edométrica unidimensional, cisalhamento triaxial consolidado não drenado, ensaio de carga em placa, penetração dinâmica leve e pesada, e teste de penetração de cone -, composição química - difraturas de raios X, fluorescência, imagens microscópicas de energia de varredura, capacidade de troca catiônica e pH -, e condutividade hidráulica através do permeâmetro de cabeça descendente permitiram correlacionar diversos parâmetros. Os resultados caracterizam o solo como um típico solo granítico, uma areia bem graduada sem plasticidade classificada como A-1-b segundo AASHTO, gravidade específica de 2,55, com compactação ótima seguindo w = 14,0% e ?d = 1,86 g/cm3. Composto principalmente por quartzo, caulinita e muscovita, juntamente com altas quantidades de SiO2 e Al2O3, além de menores porcentagens de NaO2 e Fe2O3, também apresentou pH = 6,0 e capacidade de troca catiônica = 17,0 meq/100g. O solo possui alta expansibilidade livre, porém baixa compressibilidade edométrica quando compactado, o ângulo de atrito interno efetivo é em torno de 35º e não possui coesão. Várias rodadas de testes foram feitas para esta avaliação e, como o local é estudado há mais de dez anos, foi realizada outra análise em prol do comportamento de longo prazo da estrutura. Análises de comportamento de longo prazo e correlações de parâmetros foram desenvolvidas em torno das características de compactação dentro do Normal Proctor, medidor de densidade do solo e resultados do gammadensímetro; condutividade hidráulica direta e indireta através de ensaios laboratoriais oedômetros e permeâmetros; relação de testes de perfuração entre leve e pesado de penetração dinâmica, teste de penetração padrão e testes de penetração de cone; além de oedômetro laboratorial e teste de carga em placa in-situ, a consolidação do revestimento do aterro

A literature study of the arching effects

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1996.Includes bibliographical references (leaves 190-196).by Hsien-Jen Tien.M.S

XTerramechanics: Integrated Simulation of Planetary Surface Missions

Are there contemporary habitats elsewhere in the solar system with necessary conditions, organic matter, water, energy, and nutrients to support or sustain life. Are there habitats that have experienced conditions similar to those on Earth when life emerged ,an abode of possible lifelong past. Mars and Europa(Jupiter’s icy moon)have been identified as the most relevant and immediate in the quest to answer these questions. Beyond Mars and Europa, every celestial body of interest appears to have its own geological history and every new discovery accentuates the overall complexity of our solar system. The exploration of Mars and Europa, and others, both remotely and in situ, is a central priority as part of NASA’s current and future goals for understanding the building of new worlds, the requirements for planetary habitats, and the workings of the solar system