含盐施工用水对路基填料工程特性的累加效应

针对不同含盐量的砾类硫酸盐渍土, 开展了在加入不同次数、不同含盐类型的施工用水工况下的大型压缩试验、盐胀试验、溶陷试验; 试验以现场调查数据为依据, 基于现场原位土配制了加入不同含盐施工用水类型、不同加入次数的试验土样, 观测不同土样分别在400 kPa荷载条件下、单次降温条件下以及加水溶陷条件下的变形量随时间的变化特点; 分析了多次添加含盐施工用水对砾类硫酸盐渍土工程性质的影响机理。研究结果表明: 随着含盐施工用水加入次数的增加, 砾类硫酸盐渍土的压缩变形呈现先增大后逐渐稳定的趋势, 其压缩模量表现出典型的3阶段变化规律, 且这种规律与含盐施工用水的含盐类型无关; 在降温影响下, 含硫酸盐施工用水的逐渐加入使砾类硫酸盐渍土的盐胀量呈现先显著增加后趋于稳定的趋势, 盐胀量最大增加了7.9倍, 含氯盐施工用水的逐步加入使土样的盐胀量先明显降低后趋于稳定, 最终盐胀量仅为原盐渍土盐胀量的1/13, 且含盐施工用水的加入对砾类硫酸盐渍土的盐胀特性有明显累加效应; 随着含盐施工用水加入次数的增加, 土样的溶陷变形呈不断累加趋势。可见, 盐渍土地区含盐施工用水中的易溶盐即使含量较少, 但多次使用产生的累加效应明显, 亦会对路基工程特性产生较大影响, 在施工过程中需采取预防措施。 

Cumulative effect of saline construction water on engineering properties of subgrade filling material

Large-scale compression tests, salt expansion tests, and collapsibility tests were performed under the conditions of construction water with different salt addition times and types for gravelly sulfate saline soil with different sulfate salt contents. Test preparation was based on the site investigation, and samples with different types and times of saline construction water were prepared. The variation characteristics of deformation over time were observed under the condition of a 400-kPa load, single-time temperature decrease, and adding water, respectively. The influence mechanism of adding multiple times of saline construction water on the engineering properties of gravelly sulfate saline soil was analyzed. Research results show that the compression deformation of gravelly sulfate saline soil first increases and then gradually stabilizes as the times of saline construction water increases. The compression modulus shows a typical three-stage variation law, which is independent of the type of saline construction water. Under the influence of cooling, with the gradual addition of sulfate-containing construction water, the salt expansion of gravelly sulfate saline soil tends to become stable after an obvious increase, and the maximum dilatation increases by 7.9 times. The addition of chlorine-containing construction water decreases the salt expansion and then gradually stabilizes. The ultimate salt expansion was only 1/13 that of the original saline soil. Moreover, the addition of saline construction water has an obvious cumulative effect on the salt expansion characteristics of gravelly sulfate saline soil. With the increasing times of saline water additions, the collapse deformation of soil samples shows a rule of accumulation. Therefore, even if the salt content in construction water from a saline area is low, the cumulative effect from multiple uses of construction saline water is obvious and will have a negative influence on the subgrade engineering characteristics. Preventive measures should be taken during the construction process.