The strength and brittleness of rocks are among the most important mechanical parameters in the design of geotechnical projects. Anisotropy is one of the prominent factors affecting the rock properties including strength and brittleness. This paper investigates the effect of anisotropy on the strength and brittleness of laminated sandstone samples collected from the northwest of Khorramabad (west of Iran). For this purpose, the laminated sandstone samples were drilled at different lamination angles (β) of 0°, 30°, 45°, 60°, and 90°. Here, β is the angle between lamination planes and loading direction. After preparation of specimens, petrographical and physical properties were investigated. Then, uniaxial compressive strength (UCS) and Brazilian tensile strength (BTS) tests were carried out on the specimens at different β angles, and their strengths were determined. Using data analysis, brittleness was indirectly obtained as a function of UCS and BTS. The results showed that the anisotropy of the sample has a significant influence on UCS, BTS, and brittleness. Moreover, UCS and brittleness of the sample showed a shoulder-shaped anisotropy with the maximum value at β = 0° or β = 90° and minimum value at β = 30°. Meanwhile, the BTS of the sample increased with an increase in β from 0° to 90°. According to the classifications of UCS and brittleness of rocks in the literature, in terms of the β angle, the sample falls into the different categories of rock classes.

岩石的强度和脆性是岩土工程设计中最重要的机械参数之一。各向异性是影响岩石特性（包括强度和脆性）的重要因素之一。本文研究了各向异性对从Khorramabad西北部（伊朗西部）采集的层压砂岩样品的强度和脆性的影响。为此目的，以0°，30°，45°，60°和90°的不同层压角（β）钻出层压砂岩样品。在这里，β是层压平面和加载方向之间的角度。制备标本后，研究了岩石学和物理性质。然后，在不同的β角上对样品进行单轴抗压强度（UCS）和巴西拉伸强度（BTS）测试，并确定它们的强度。使用数据分析，间接获得了脆性，作为UCS和BTS的函数。结果表明，样品的各向异性对UCS，BTS和脆性有显着影响。此外，样品的UCS和脆性显示出肩状的各向异性，其最大值在β  = 0°或β  = 90°处，最小值在β处 = 30°。同时，样品的BTS随着β从0°增加到90°而增加。根据文献中UCS的分类和岩石的脆性，就β角而言，样本属于岩石类别的不同类别。