水、孔洞及层理耦合作用下的千枚岩巴西劈裂试验研究

Experimental study on Brazilian splitting of phyllite under the coupling effects of water, pore and bedding

千枚岩普遍分布于我国西南地区,地下水、层理、微孔隙以及微裂隙等因素均会在一定程度上削弱其力学特性,进而给相关工程的稳定性问题提出严峻挑战。基于巴西劈裂试验,研究了水、层理以及孔洞共同耦合作用下千枚岩的抗拉强度、能量以及破坏形式。研究表明:抗拉强度随含水率、孔径以及层理角度的增加均表现出逐渐下降的趋势,但是,抗拉强度对含水率、孔径以及层理角度的变化具有不同的敏感性,主要体现为层理角度最为显著,孔径大小次之,含水率最小;不同层理下的抗拉强度具有明显的各向异性,抗拉强度的各向异性度随含水率以及孔径的增加而增加,且其随含水率的增加速率更为显著;能量随含水率、孔径以及层理角度的增加逐渐增加,与抗拉强度的变化规律具有一致性;不同层理下的能量亦表现出明显的各向异性,但其各向异性度普遍大于同等条件下的抗拉强度的各向异性度;试件破坏形式受孔径、层理角度以及含水率等因素的影响,其中,孔洞的存在主要影响裂纹起裂位置,孔径大小主要影响裂纹起裂强度,层理角度主要影响裂纹扩展路径,含水率主要影响裂纹数量。该研究成果对于更加深入地理解岩石抗拉特性以及提升岩土工程稳定性均具一定价值。

Phylite is widely distributed in southwest of China. Factors such as groundwater, bedding, micro-pores and micro-cracks will weaken its mechanical properties to some extent, thus posing severe challenges to the stability of the related projects. Therefore, in this paper, based on Brazilian splitting test, the evolutions of the tensile strength, energy and failure forms of phyllite under the coupling effects of water, bedding and pore are studied. The results show that the tensile strength decreases gradually with the increase of moisture content, pore diameter and bedding angle. However, the tensile strength has different sensitivities to the changes of them, which is mainly reflected in that bedding angle is the most significant, pore diameter is the second, and moisture content is the least. The tensile strength shows obvious anisotropy under different beddings. The anisotropy of tensile strength increases with the increase of water content and pore diameter, and the rate of increase with water content is more significant. Moreover, the energy increases gradually with the increase of moisture content, pore diameter and bedding angle, which is consistent with the changes of tensile strength. Although the energy under different beddings also presents obvious anisotropy, its anisotropy degree is generally higher than that of the tensile strength under the same condition. The failure form of specimens is affected by pore size, bedding angle and moisture content, among which, the existence of hole mainly affects the crack initiation position, the size of pore mainly affects the crack initiation strength, the bedding angle mainly affects the crack propagation path, and the moisture content mainly affects the number of cracks. This research results are valuable for further understanding the tensile properties of rocks and improving the stability of geotechnical engineering.