共面双裂隙类岩石材料抗拉强度试验研究

EXPERIMENTAL STUDY ON THE TENSILE STRENGTH OF ROCK-LIKE MATERIALS CONTAINING TWO PRE-EXISTING COPLANAR FISSURES

研究裂隙充填下岩石的力学特性对确保裂隙岩体的稳定性具有重要意义。该文首先配制了不同裂隙倾角下充填与非充填共面双裂隙巴西圆盘类岩石试样,然后在DNS 300岩石伺服机上进行巴西劈裂试验。基于试验结果,分析了裂隙倾角及裂隙充填与否对试样抗拉强度的影响,并结合其声发射特征和数字散斑系统对试样的裂纹扩展过程进行分析。结果表明:相比非充填试样,裂隙充填一定程度上增加了试样的完整性,使其抗拉强度有所增加;无论试样裂隙充填与否,其抗拉强度都受裂隙倾角的影响,随着裂隙倾角的增加,充填与非充填试样的抗拉强度逐渐呈现下降趋势;裂隙倾角在15°以内和为90°时,裂隙充填与否对试样的破裂模式基本没有影响;而裂隙倾角介于30°和75°之间时对其破裂模式影响较大,且随着裂隙倾角的增加,在形态上充填与非充填试样的破裂模式都由拉张裂纹向翼裂纹转变。

It is of great importance to study the mechanical properties of rock containing filling fissures to ensure the stability of fractured rock mass.The filling and non-filling coplanar double-fissures Brazilian disc rock-like samples with different fissure angles are prepared and the Brazilian splitting tests were performed on a DNS 300 rock servo machine.Based on the test results,the influence of crack inclination and crack filling on the tensile strength of the specimens was analyzed.The crack propagation process was also analyzed based on its acoustic emission characteristics and a digital speckle system.The main conclusions are drawn as follows:Compared with non-filling samples,the crack filling increases the integrity of the sample to some extent and increases its tensile strength;regardless of whether the cracks of the sample are filled or not,the tensile strength is affected by the crack inclination.With the increase of the crack inclination,the tensile strength of the filled and non-filled specimens shows an downward trend gradually;the crack filling has little effect on the failure mode of the sample when the crack inclination angle α≤15°and α=90°,but it has a great influence on the failure mode when 30°≤α≤75°.Asαincreases,the failure modes of both filled and non-filled specimens change from tensile cracks to wing cracks in morphology.