The presence of water in sandstones has caused many engineering geology disasters. In order to investigate the weakening mechanism of the clay-bearing green sandstone caused by water at different ambient temperature, the main water treatments have been conducted in this research, including dry-wet cycles, water immersion and freeze-thaw cycles. It shows that the repeated dry-wet cycles have little effect on the mechanical strength of this sandstone due to the lack of expansive clay minerals like montmorillonite. However, the water immersion and cyclic freeze-thaw treatments have caused a remarkable reduction of the strength. The UCS (uniaxial compressive strength) of this green sandstone has decreased by 27.2% from the dry to saturated state and it continues to decline for another 31.1% after 60 times of freeze-thaw cycles. In addition, the internal friction angle has a little increment but the cohesion decreases quickly with increasing freeze-thaw cycles. The adverse influence of the freeze-thaw damage on the TCS (triaxial compressive strength) would be inhibited by the confining pressure, because the pores and microcracks were compacted under a high confining pressure. The novel findings of this study are that the reversible physical softening should be responsible for the water weakening of this clay-bearing green sandstone above 0 °C, and the freeze-thaw damage is irreversible due to the production of plastic frost heaving deformation below 0 °C. Therefore, it is suggested that the effect of water weakening on the mechanical properties of the green sandstone should be considered in the wet state regardless of the number of dry-wet cycles, especially in cold regions.

砂岩中水的存在引起了许多工程地质灾害。为了研究在不同环境温度下水引起的含粘土绿砂岩的弱化机理，本研究进行了主要的水处理，包括干湿循环，水浸和冻融循环。结果表明，重复的干湿循环对这种砂岩的机械强度影响不大，这是由于缺少像蒙脱石这样的膨胀粘土矿物。但是，水浸和循环冻融处理导致强度显着降低。这种绿色砂岩的UCS（单轴抗压强度）从干态到饱和态下降了27.2％，经过60次冻融循环后又继续下降了31.1％。此外，内摩擦角略有增加，但随着冻融循环次数的增加，内聚力迅速降低。冻结-融化破坏对TCS（三轴抗压强度）的不利影响将被约束压力所抑制，因为孔和微裂纹在较高的约束压力下被压实。这项研究的新发现是，可逆的物理软化应是造成该黏土生砂岩在0°C以上水软化的原因，并且由于0以下的塑性冻胀变形的产生，冻融破坏是不可逆的。 ℃。因此，建议无论干湿循环的次数如何，都应在湿润状态下考虑水减弱对绿色砂岩力学性能的影响，尤其是在寒冷地区。