## 3 Results and Discussion
### Strength Change
#### 3.3.2 Strength Comparison  
For the full-through fracture grout-reinforced specimens, it can be seen from the data in Figure 10 that after soaking in an acid solution, the change law of the compressive strength of the full-through fracture grout-reinforced specimens is similar to that of the original grout-reinforced specimens. The angle of immersion increases from 0\({}^{\circ}\) to 60\({}^{\circ}\), and the compressive strength of the solid addition gradually decreases. Meanwhile, the compressive strength of the grout-reinforced specimens for the 90\({}^{\circ}\) crack is between 45\({}^{\circ}\) and 60\({}^{\circ}\). The compressive strength of grout-reinforced specimens after soaking in an acid solution is significantly lower than that of untreated grout-reinforced specimens, and with the increase of fracture angle, the compressive strength of grout-reinforced specimens after soaking in acid solution is greater than that of untreated fracture grout-reinforced specimens. The uniaxial compressive strength of fracture grout-reinforced specimens with fracture  
Figure 9: Grout-reinforced specimens unconfined compressive stress–strain curve: (**a**) full-through fracture grout-reinforced specimens; (**b**) full-through grout-reinforced specimens after soaking in acidic solution; (**c**). semi-through fracture grout-reinforced specimens; (**d**) semi-through fracture grout-reinforced specimens after soaking in acidic solution. inclinations of 0\({}^{\circ}\), 30\({}^{\circ}\), 45\({}^{\circ}\), 60\({}^{\circ}\), and 90\({}^{\circ}\) decrease by 4.11%, 7.19%, 9.57%, 13.03%, and 6.84%, respectively. Compared to the full-through fracture grout-reinforced specimens, the correlation between the strength of the semi-through fracture grout-reinforced specimens and the fracture inclination angle is lower between 0\({}^{\circ}\) and 60\({}^{\circ}\), and the compressive strength of the specimen is greatest when the fracture is 90\({}^{\circ}\). For full-through grout-reinforced specimens after different freeze-thaw cycles in an acidic environment when the number of freeze-thaw cycles is zero, five, and ten, the compressive strength decline of the sample is close to a straight line, and the decline rate of compressive strength gradually decreases after 20 freeze-thaw cycles and 30 freeze-thaw cycles. When the number of freeze-thaw cycles was five, the uniaxial compressive strength decreased from 26.72 MPa to 12.02 MPa with a decrease of 55.01%. When the number of freeze-thaw cycles was 10, the uniaxial compressive strength decreased from 21.76 MPa to 7.41 MPa, a decrease of 65.95%. When the number of freeze-thaw cycles is 20, the uniaxial compressive strength decreases from 18.23 MPa to 4.18 MPa, a decrease of 77.07%. When the number of freeze-thaw cycles was 30, the uniaxial compressive strength decreased from 16.19 MPa to 2.98 MPa, a decrease of 81.6%. It can be seen that as the number of freeze-thaw cycles increases, the compressive strength of the grout and solid with a crack angle of 60\({}^{\circ}\) decreases more than that of the grout and solid with a crack angle of 0\({}^{\circ}\). For semi-through grout-reinforced specimens after different freeze-thaw cycles in an acidic environment when the number of freeze-thaw cycles is five, the uniaxial compressive strength decreases from 28.68 MPa to 21.89 MPa, a decrease of 23.67%. When the number of freeze-thaw cycles is 10, the uniaxial compressive strength decreases from 25.12 MPa to 18.18 MPa, a decrease of 27.62%. When the number of freeze-thaw cycles was 20, the uniaxial compressive strength decreased from 22.58 MPa to 16.84 MPa, a decrease of 25.42%. When the number of freeze-thaw cycles was 30, the uniaxial compressive strength decreased from 21.05 MPa to 12.18 MPa, a decrease of 42.13%. It can be seen that the compressive strength of semi-through grout-reinforced specimens decreases relatively less with the increase in the number of freeze-thaw cycles compared to full-through grout-reinforced specimens.