Preparation of materials in the annular space of freezing holes and microscopic research under freeze-thaw conditions

SUN Mingrui; CHENG Hua; LI Ziqing; XUE Weipei; QI Yanqiu; WANG Xiaoyun; GUO Longhui; ZHANG Zhiwei

doi:10.19458/j.cnki.cn11-2456/td.2025.04.014

Abstract：In order to solve the problems such as the water inrush in the external annular channel of the freezing pipes in the shaft sinking project by the freezing method in the western region,the influence of four factors including the water-cement ratio,citric acid,sodium pyrophosphate,and boric acid on the retarding cement slurry,as well as the internal pore changes of the compacted mass after freeze-thaw damage,were studied by combining the orthogonal test and range analysis method.The results show that:① Boric acid is a significant influencing factor for fluidity,and sodium pyrophosphate has the most significant influence on the initial setting time,while the water-cement ratio plays a dominant role in the compacted mass ratio,strength,and permeability.② Through the efficacy coefficient meth-od,it is determined that when the optimal proportion is a water-cement ratio of 1.1,0.18％citric acid,0.35％sodium pyrophosphate,and 0.25％boric acid,the comprehensive performance of the retarding cement slurry is the best.③ The microstructure analysis shows that the compacted mass is mainly composed of micron-sized small pores,among which the area of small-sized pores is the largest,far greater than the sum of the areas of medium-sized pores and large-sized pores.After the freeze-thaw process,the number of internal pores increases,so the measured porosity of the compacted mass shows an upward trend.By comparing the pore size distribution diagrams before and after freeze-thaw,it can be found that the distribution proportions of gel pores,capillary pores,and non-capillary poresall increase,and the capillary pores account for the largest proportion,followed by the gel pores,and the non-capillary pores are the smallest.The research results can provide useful references for the preparation of retarding slurry in shaft sinking by the freezing method in the western region.