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Abstract The interaction between the drilling machine and the lunar soil in the special environments on lunar surface has been the key issue of sampling in lunar regolith. Direct shear tests，compression tests and triaxial tests were carried out to investigate the mechanical property of lunar regolith simulant CAS–1 under the low levels of stress. The simulant was found to have the cohesion of 2.8 to 5.0 kPa and the angle of internal friction 39.84°to 41.09°when the porosity e = 0.8–1.1 at the low stress level. The compression curve was found to have a shape of concave upward firstly and then a shape of concave downward at the low stress levels. The initial compression moduli were from 12.647 to 3.923 MPa when e = 0.9–1.1. The stress-strain curve can be divided into a harden and a soften stage. The decreasing rate of the soften stage is rather fast and the duration of the residual strength is long. When the void ratio is smaller，the ratio of peak deviator stress/stress is larger，the peak axial strain is smaller and the values of peak axial strain are between 2% and 5%，the ratio of residual strength/stress is larger and the duration is longer. The initial tangent of the stress-strain curve，the peak stress ratio and the residual stress ratio vary with the compression stress logarithmically. The initial tangent decreases slowly， the initial tangent modulus changes little but the peak stress ratio and the residual stress ratio decrease rapidly.
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Received: 09 January 2014
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2015, Vol. 34 
