## 3 Experimental Design
### Result Analysis
#### 3.3.3 Variation in Compaction Stress  
After water absorption and expansion, the compaction segment radially compresses the surrounding soil. Under the combined effects of temperature and radial stress, the soil undergoes drainage and consolidation, with the radial compaction stress determining the effectiveness of this process. Figure 12 shows the curves of compaction stress in the soil around water-absorbing and compacting membrane bags of different diameters over time. According to Figure 12, the 1# mortar-bonded anchor rod does not generate compaction stress in the surrounding soil due to the absence of an expansion force source. However, for the 2#, 3#, and 4# water-absorbing and compacting anchor rods, the quicklime absorption and expansion create an expansion force source in the radial direction of the membrane bag, prompting the surrounding soil to generate radial compaction stress. The compaction stress at each measurement point exhibits the characteristics of slow initial growth, subsequent rapid growth, and finally gradual stabilization. Initial Stage: In the early stage after the anchor rod is installed and begins to absorb water and expand, the radial earth pressure remains relatively stable or only exhibits minor changes since the expansion has not significantly affected the surrounding soil. Growth Stage: As the quicklime absorbs water, expands, and undergoes a curing reaction, the surrounding soil of the anchor rod begins to experience radial compaction, leading to a gradual increase in the radial earth pressure. The growth rate during this stage may vary depending on the soil properties, anchor rod diameter, and characteristics of the expansion material. Peak Stage: When the expansion of the anchor rod reaches a certain level, the compaction effect on the surrounding soil also maximizes, resulting in the radial earth pressure reaching its peak. The time at which the peak occurs depends on the reaction rate of the expansion material and the consolidation characteristics of the soil. Stable Stage: After the peak, as the soil gradually drains and consolidates and the expansion effect of the anchor rod weakens, the radial earth pressure tends to stabilize. However, this stable state may represent a dynamic equilibrium process where the earth pressure fluctuates within a certain range. Figure 11: Pore water pressure–time curve in the soil around the water-absorbing and compacting membrane bag. (**a**) Radial pore water pressure–time curve around the 1# anchor rod. (**b**) Radial pore water pressure–time curve around the 2# anchor rod. (**c**) Radial pore water pressure–time curve around the 3# anchor rod. (**d**) Radial pore water pressure–time curve around the 4# anchor rod. Figure 12: _Cont._  
The larger the diameter of the water-absorbing and compacting membrane bag, the greater the radial expansion and compaction stress, and the longer the time required to reach stability. The closer the distance to the membrane bag, the greater the expansion and compaction stress. The peak radial compaction stresses at a 5 cm distance from the surrounding areas of the 2\(\mu\), 3\(\mu\), and 4\(\mu\) water-absorbing and compacting anchor rods are, respectively, 15.7 kPa, 42.2 kPa, and 48.2 kPa. The peak stress occurs 6-10 h after the start of the maturation reaction, lagging behind the peak temperature time. Figure 13 shows the variation curve of compaction stress in the soil surrounding a water-absorbing and compacting membrane bag along its radial direction. As can be seen from Figure 13, the distribution trend of compaction stress in the soil surrounding water-absorbing and compacting anchoring rods of different diameters is the same along the radial direction. The larger the expansion force source is, the greater the transmission range of compaction stress will be, which is characterized by a slow decrease followed by a rapid decrease along the radial direction. Figure 12: Time-varying curve of compaction stress in the soil around a water-absorbing and compacting membrane bag.