风化条件下高水材料强度劣化试验研究

近年来高水材料广泛用于煤矿巷旁充填、注浆加固和堵孔阻漏等工程领域,但易风化仍然是高水材料固有缺陷。为探究高水充填材料风化后的物理力学性质及风化机理,通过ETM力学试验系统对不同风化天数的高水材料进行研究。结果表明：高水材料风化主要是由于空气中的二氧化碳与钙矾石晶体发生反应,且随着风化天数的增加,自由水的流失与钙矾石晶体的逐渐解体会降低材料密实度,间接加速二氧化碳与钙矾石的反应,因此高水材料失水速率与劣化度随着风化天数增加而增大,且呈上升趋势；风化后的高水材料由表及里会形成风化层-过渡层-未风化层结构,风化层呈粉末状,受压即会破坏脱落,几乎不具备承载能力,但过渡层和未风化层仍然具备一定的承载能力；未风化的试件受压过程中会有水分溢出,风化后的试件无水分溢出。未风化的试件破坏形式属于劈裂破坏,风化后的试件破坏则都是在端部出现剪切破坏,剪切带周围会出现许多微裂隙。可见高水充填材料耐久性与其所处环境湿度密切相关。

High Water Material Strength Degradation Experiments Under the Condition of Weathering

In recent years, high water materials are wildly used in engineering fields, such as coal roadway filling, grouting reinforcement and water plugging, But the high water material easy weathering is its inherent defect. In order to explore the physical and mechanical properties and weathering mechanism of high water filling material after weathering, high water materials of different weathering days were studied by means of ETM mechanical test system. The results shows that: high water material weathering is due to the reaction of carbon dioxide and calcium alunite , and with the increase of weathering days, the loss of free water and the gradual dissolution of calcium alunite crystals will reduce the compactness of materials and accelerate the reaction of carbon dioxide and calcium alunite. Therefore, the rate of water loss and degradation of high water materials increase with the number of days of weathering, and it shows an upward trend. The high water material after weathering will form the structure of weathering layer, transition layer and unweathered layer from the surface to the inside. The weathering layer is in the form of power, which will break off when subjected to pressure. It hardly has the bearing capacity, but the transition layer and unweathered layer still have a certain bearing capacity. The unweathered specimens may overflow with water when subjected to pressure, while the weathered specimens do not overflow with water. The failure mode of unweathered specimens belongs to splitting failure, while the destruction of weathered specimens is shear failure at the end, and there are many micro-cracks around the shear zone. It is concluded that the durability of high water filling materials is closely related to the environmental humidity.