## 1 Introduction  
At present, water-bearing fractures and Quaternary sand are the most studied sources of water seepage in the field of groundwater prevention and control. Because the hydraulic conductivity of fractures is better than that of pores, the prevention and control of fracture water in rock has attracted considerable attention from many scholars [1; 2; 3; 4]. Quaternary sandy soil has a loose structure and abundant pore water, which is a primary concern for hydrogeology and civil engineering projects [5; 6; 7; 8]. However, in the past 20 years, an increasing number of deep projects, including deep coal mining, deep tunnel construction, deep oil and gas storage, and deep nuclear waste storage, have been constructed [9; 10; 11; 12], and the mining conditions in deep areas are different from those in shallow areas, with \"three-high\" characteristics (\"three-high\" refers to a high confining pressure, high water pressure and high temperature; in this paper, water pressure refers to the pore water pressure) [13]. Accordingly, many new problems that have an impact on engineering projects have emerged, such as the problem of pore water seepage from deep sandstone. As cemented sandstones generally have a low-to-medium permeability (0.1-500 mD), with a small amount of pore water seepage and little impact on shallow engineering projects, few researchers have studied the influence of pore seepage of cemented sandstones on shallow engineering projects. However, the situation is quite different for deep engineering projects. For example, most of the strata that are crossed by deep mining shafts are sedimentary sandstones with abundant water and developed pores [14]. Water seepage and gushing from sandstone often occur in shaft construction. Years of experience in grouting sandstone aquifers to plug water seepage in deep mining shafts have shown that even when cementing and chemical grouting are carried out in the rock mass behind the wall and the main water inflow channels (fractures) in the rock mass are effectively blocked, residual water can still seep through sandstone pores in the shaft wall. This seepage cannot be ignored, because the total water leakage exceeds the upper limit of the accepted specification (\(\leq\)10 m\({}^{3}\)/h) [15; 16]. The difficulty of grouting porous sandstone has become a bottleneck that restricts the rapid excavation and normal handover of shafts [14; 17]. At present, pore seepage influences the production of deep shafts in many coal mines, such as some deep coal mines in the Ordos, Ningdong, Longdong and Binchang mining areas [14] and the Tangkou, Anju, Huafeng and Xiezhuang coal mines in the Southwest Shandong coalfield [18; 19]. There are two main reasons for the above phenomenon: first, the deep environment is characterized by \"three-high\" characteristics; second, some types of sandstone pore structures can allow large-area pore seepage under these \"three-high\" conditions, resulting in a significant increase in the seepage flow rate, which can become fast enough to affect normal production. Therefore, the study of the permeability evolution of deep sandstones with different pore structures under the \"three-high\" conditions is urgent for improving the production of many deep coal mines. To date, some researchers have studied the influence of the \"three-high\" factors on rock pore permeability from a theoretical perspective. [PERSON] (1965) conducted heating tests on a large number of sandstone cores at 400-800 \({}^{\circ}\)C and found that the permeability of broken cores increased by 50% [20]. [PERSON] (1968) conducted a permeability test on granite under high pressure and found that the pore permeability of granite decreased with increasing effective confining pressure (the difference between the confining pressure and pore pressure) [21]. [PERSON] (1982) heated Adamellite to 300 \({}^{\circ}\)C under different confining pressures, which made the rock fracture and its permeability increase several times [22]. [PERSON] et al.