Abstract
A biaxial shear test is performed on prefabricated, single-fissure type, cubic rock-like specimens by using the TZW-500 rock direct shear apparatus to study the shear strength characteristics, crack coalescence, and propagation modes of the specimens with different geometric parameters. Results show that the crack coalescence and propagation modes of the rock-like specimens with prefabricated fissures can be divided into four types, namely, single main shear crack coalescence mode, main shear crack coalescence and secondary tensile-shear crack propagation mode, main shear crack coalescence and secondary shear crack propagation mode, and main shear crack coalescence and secondary tensile crack propagation mode. All modes are affected by the dip angle α and length l of the prefabricated fissure. When the dip angle of the prefabricated fissure is α∈[0°, 20°) or (70°, 90°], the cracks center on shear failure, and most shear cracks propagate along one end of the prefabricated fissure. At α∈(30°, 50°), the cracks bear the tensile-shear combined action, and the shear cracks propagate along the two ends of the prefabricated fissure. The peak shear strength of the rock-like specimens with prefabricated fissures is also closely related to the dip angle α and length l of the fissure. With the increase in dip angle α of the prefabricated fissure, the peak shear strength of each rock-like specimen decreases initially then increases, and the peak shear strength curve presents a similar “U” shape. At α∈[30°, 60°], the peak shear strength is within the peak-valley interval. When the length l of the prefabricated fissure is increased, the peak shear strength experiences a gradual reduction. When l > 20 mm, the peak shear strength is greatly influenced by l, but the influence is minimal when l ≥ 20 mm. At the same dip angle α and fissure length of l ≥ 20 mm, the correlation between peak shear strength and fissure width b is low.
Highlights
Cubic rock-like specimens containing a single fissure were prefabricated to conduct a biaxial shear test, and their strength characteristics, crack coalescence, and propagation modes were explored under different geometric conditions. e following main conclusions were derived: (1) When the dip angle α of the prefabricated fissure increased, the peak shear strength of the rock-like specimens decreased initially, increased, and the peak shear strength curve presented a similar “U” shape
At α ∈ [30°, 60°], the peak shear strength was in the peak-valley interval; the minimum peak shear strength of each curve accounted for 43%–64% of the peak shear strength of the intact specimen
At α 90° and different lengths l and widths b of the prefabricated fissure, the peak shear strengths of all specimens reached the maximum values. e maximum shear strength of each curve accounted for 63%–79% of the peak shear strength of the intact specimen
Summary
Model [5,6,7,8,9,10,11,12,13] and numerical [14,15,16,17,18,19] tests are usually used in present studies on the crack propagation mode and strength characteristics of joint fissure-containing rock mass. Rough a model material test, numerical simulation, and real rock material test, other studies [5,6,7,8,9, 22,23,24,25,26] systematically investigated the strength deformation characteristics and crack propagation modes of rock specimens containing one, two, three, or more fissures under uniaxial compression. Crack coalescence and propagation modes were examined. e results are expected to provide a reference for rock slope engineering design and slope stability control
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
