【摘要】 用水压致裂法对7种岩石的厚壁圆筒试件进行不同围压下的抗拉强度实验,并从试件致裂瞬间的内壁环向应力σt,环向应变εt等五种参数随围压变化的角度,对围压条件下岩石的抗拉强度进行研究。结果表明,若用σt表示岩石的应力抗拉强度,则σt随围压的增加而减少,并由低围压时的拉应力逐渐过渡为高围压时的压应力。高围压时,虽然试件已处于三向受压状态,但其破裂仍表现为典型的张性破裂。从另一意义上讲,处于高围压环境中的岩石,其内部不可能存在拉应力,拉应力只在低围压状态中存在。若岩石的应变抗拉强度由εt表示,即使岩石三向受压,张性破裂的εt始终是拉应变,岩石的抗拉强度由应变来表征似乎更合理。εt先随围压的增大而增大,当围压超过某一特征值后,εt反随围压的增大而有所减少。 将上述结果应用于岩体（或地震）破裂,可以证明,当岩体内存在σ₃<μ（σ₁+σ₂）的应力状态时,即使三向受压,岩体照样会出现张性破裂。由此认为,地震的震源也存在着张性破裂的可能。更多还原

【Abstract】 Tension resistent strength of rock under confining pressure is examined by experiments of applying hydraulic fracturing method with different confining pressure upon thick-walled cylindrical specimens of seven kinds of rock and by adopting the rules of five parameters like inner wall circular stress at and circular strain gt at the fracture instant of specimen along with the variation of confining pressure. The result shows that when at indicates the tension resistent strength of the rock, the tension resistent strength of rock decreases with the increas of confining pressure, and that the tension strain at low confining pressure gradually transits to the pressure strain at high confining pressure. At high confining pressure, it shows typical tensile fracture, even the specimen suffers from three-directional pressure. From another point of view, tension strain could not exist in the rock under high confining pressure, it could only exist under low confining pressure. And when εt indicates the tension resistent strength of the rock, the εt of tensile fracture is always the tension strain, even if the rock sits are in three-directional pressure. It seems rationally to express the tension resistent strength of rock by the strain. At first the  increases with the increase of confining pressure, then it decreases after the confining pressure reaches to a certain specific value.Applying the above results upon rock fracture or earthquake, it can be proven that once an σ3<μ(σ1 +σ2) stress exists in the rock, tensile fracture will appear in the rock even it suffers from three-directional pressure. Thus it can be seen that tensile fracture may occur at a seismic focus.更多还原