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In order to study the influence of the stress direction during underground engineering excavation on the strength of weakly cemented soft rock, the soft rock samples were obtained from the coal mine roadway engineering soft rock and the GDS(Global Digital Systems) hollow cylindrical test system was used to determine the average fixed principal stress. The deviation stress under the action of the rotation of the principal stress axes, the stress path of the soft rock mechanics, and rotation angle of the principal stress axes of weakly consolidated soft rock specimen were studied, and the stress-strain characteristics as well as the influence of the strength characteristics was determined. Based on the test results and power function model, an empirical equation of the shear strain of weakly consolidated soft rock under the principal stress axis was established. The results show that the deformation of weakly consolidated soft rock accumulates with the rotation of the principal stress axis, and with the rotation angle of the principal stress axis increases, the axial strain and shear strain rates increase rapidly, and the cumulative deformation also increases.The rotation of the principal stress axis accelerates the accumulation of the axial strain of the specimens.The shear formular can effectively predict the shear strain variation law of weakly consolidated soft rock under the stress axis rotation. Additionally, it can be applied in the deformation prediction of practical engineering. [ABSTRACT FROM AUTHOR]

In order to study the shear strength characteristics of polypropylene fiber-reinforced cement aeolian sand, the orthogonal test method was used to conduct unconsolidated undrained triaxial (UU) test to study the effects of fiber content, fiber length, cement content, and water content on the shear strength of fiber-reinforced cement aeolian sand. The results show that the main and secondary factors influencing the shear strength of fiber-reinforced aeolite sand are cement content, fiber length, water content, and fiber content.The optimal test ratio is cement content 10%, fiber length 12 mm, water content 8% and fiber content 0.2%. The peak stress and strain of cement eolian sand can be significantly increased by adding the appropriate amount of fiber into the sample. The cohesion increases first and then decreases with the increase of fiber content, and increases with the increase of fiber length. The influence of fiber content on internal friction angle is small. The research results can provide the scientific basis for the prevention and treatment of fiber-reinforced cement eolian sand roadbeds. [ABSTRACT FROM AUTHOR]