水泥基注浆材料析水时变特性量化试验研究

水泥基胶结性材料是注浆工程中最常见的注浆材料，这类材料存在明显的析水效应，获得析水厚度的量化公式有助于提高浆液扩散半径的计算精度。通过试验观察叶腊石粉掺量(0%~35%)、聚乙烯醇掺量(0%~8%)与粉煤灰掺量(0%~90%)3种掺合料在水泥基浆液中的析水过程，获得三者的析水率、结石率、最终析水时间与析水厚度变化情况，认定浆液的析水厚度变化存在一定规律的析水时变特性，并引入皮尔生长曲线模型与幂函数模型，对其进行量化。结果表明:3种掺合料都可以降低析水率，其中，叶腊石粉对水泥基注浆材料析水率的影响程度最大，其次为粉煤灰，最后为聚乙烯醇；3种掺合料都可以增加结石率；叶腊石粉可以有效缩短浆液的最终析水时间，聚乙烯醇在1.5%~8.0%掺量内可以缩短浆液的最终析水时间，粉煤灰在10%~60%掺量内可以缩短浆液的最终析水时间；3种掺合料掺量的变化曲线都呈现半“C”形；采用数学模型对析水厚度数据进行拟合分析，由拟合优度R2评判可知，幂函数模型优于皮尔生长曲线模型，析水厚度变化规律比较符合幂函数模型。研究成果可为改良注浆材料和完善非稳定浆液运移扩散理论提供重要的基础数据。 

Quantitative experimental study on time-varying characteristics of bleeding of cement-based grouting materials

Cement-based cementitious materials are the most common grouting materials for grouting engineering. This type of material has obvious water separation effect, and obtaining the quantitative formula of water separation thickness will be helpful to improve the calculation accuracy of slurry diffusion radius. By observing the water separation process of three admixtures, namely pyrophyllite powder (0%-35%), polyvinyl alcohol (0%-8%) and fly ash (0%-90%) in cement-based slurry, the water separating rate, stone formation rate, final water separation time and water separation thickness of the three admixtures were obtained. It is found that the water separation thickness of the slurry varies regularly with time to some extent, which is called the time-varying characteristic of water separation. In order to quantify the time-varying characteristic of water separation, the Pearl growth curve model and the power function model were introduced. The results show that all the three admixtures can reduce the water separation rate. Specifically, pyrophyllite powder has the greatest influence on the water separation rate of cement-based grouting materials, followed by fly ash, and finally polyvinyl alcohol. Meanwhile, all three admixtures can increase the stone formation rates. Besides, pyrophyllite powder can effectively shorten the final water separation time of the slurry, and the polyvinyl alcohol at a dosage of 1.5%-8.0%, as well as the fly ash at a dosage of 10%-60%, can shorten the final water separation time of slurry. Moreover, the change curves of the dosage of three admixtures are present in a “half-C” shape. Further, the data on water separation thickness were fitted and analyzed with the mathematical model. According to the goodness of fit R2, the power function model is better than the Pearl growth curve model, and the change law of water separation thickness is more consistent with the power function model. Generally, the research results can provide important basic data for improving the grouting materials and perfecting the migration and diffusion theory of unsteady slurry.