Exothermic Characteristics of the Polymerization Reaction of Weakly Exothermic Polymer Grouting Materials and Their Influence on the Hydrothermal Properties of Frozen Soil

Abstract

Weakly exothermic polymer grouting materials are used to repair the thaw settlement of roads in permafrost regions. In this study, the heat release characteristics of these materials were tested, and a visual polymer grouting model box consisting of steel plating and transparent acrylic glass was developed to conduct the model test of water and heat transfer in frozen soil. Based on the control equation of the water–heat coupling transfer in frozen soil, an analysis model of water–heat coupling in frozen soil was established, and the water–heat transfer process in frozen soil under exothermic conditions of the polymerization reaction of weakly exothermic polymer grouting materials was studied. The results demonstrate a power function relationship between the curing reaction temperature threshold and the density of weakly exothermic polymer grouting materials at different temperatures. The influence of the polymerization exothermic reaction on the moisture content and heat of frozen soil can be divided into two processes: thawing and freezing. The thawing process can be divided into three stages: slow, fast, and stable thawing. The maximum thawing depth of frozen soil has a positive correlation with the amount of grouting and the grout–soil contact area and a negative correlation with the water content of frozen soil. The initial temperature of frozen soil is selected as the common influence factor, and the prediction model of the influence of the amount of grouting, grout–soil contact area, and frozen-soil mass moisture content on the water content and heat of frozen soil is established. During the freezing process, with the continuous effect of low ambient temperature, liquid pore water at the thawing front will be refrozen. Therefore, in an actual project of the weakly exothermic polymer grouting repair of a subgrade in a permafrost region, the thermal disturbance of polymerization exothermic to the frozen subgrade can be further weakened by delaying the opening time to traffic.