## 4 Conclusions  
Fracture and damage in unsaturated porous media can be caused by a tensile crack (due to mechanical loading), thermal crack (temperature difference), and shrinkage crack (loss of moisture). This cracking is a complex behavior that is due to multiphase (solid, fluid, gas, and heat) interactions. With respect to climate change, environmental loading may accelerate the instability of unsaturated porous media, which may comprise practical problems including slope stability, retaining wall, masonry wall, etc., under cyclic wetting and drying or extreme heatwave. Therefore, simulating the damage behavior of a multiphase non-isothermal system is essential to understand such failures properly.  
In this study, we have designed two numerical examples to simulate potential failure scenarios associated with climate change to better understand its impact on unsaturated porous media. The previous study [23] has been recast and improved to capture a heat and moisture flow associated with the fracture of unsaturated porous media. The proposed model combines the simultaneous movement of moisture and heat in deformable porous media with a cohesive crack model, which employs the extended finite element method (XFEM) to include strong and weak discontinuities in the model framework.  
In the first example, the tracking functions of cracks are modified, and the local exchange of flows is calculated for each crack for the consideration of multiple crack propagation. Suction, cohesive traction, saturation degree, crack opening, and load displacement are compared for the case of two crack propagation in an unsaturated plate with the single crack propagation in that plate. The effects of parameters such as intrinsic permeability and initial crack length on the obtained results are studied. When intrinsic permeability and initial crack length decrease, the applied suction to crack faces increases, and the plate could sustain higher loads and ruptures later in the analysis. In the second example, the degradation of a masonry wall due to climatic loading is investigated. As the plaster on a brick wall dries, it shrinks, and a crack is formed on the unrestricted part of it when it deforms in the cavity between the bricks. Suction surges along the crack and prevents excessive crack opening. When the temperature rises in the outside environment, suction rises at the crack mouth, but this increased suction cannot reduce crack mouth opening displacement (CMOD). As the mass transfer coefficient of the outside environment rises, the suction increases at the crack mouth and reduces CMOD, but since the plaster dries faster, the analysis terminates prematurely. The results of numerical tests demonstrate the capabilities of the proposed model for practical application associated with climate change well.  
Figure 17: Variations of (**a**) suction and (**b**) opening at the crack mouth over time for different mass transfer coefficients. In this figure, the effect of mass transfer coefficient on the failure of the wall is examined (Equation (19)).  
**Author Contributions:** Conceptualization, A.M.V., E.M.H., and B.G.; writing--original draft preparation, E.M.H. and A.M.V.; writing--review, improve, and editing, S.N. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research received no external funding.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author.  
**Acknowledgments:** We would like to gratefully acknowledge the advice and comments of [PERSON] and [PERSON], their help was invaluable.  
**Conflicts of Interest:** The authors declare no conflict of interest.