# Research on the Settlement Patterns of Tunnel-Surrounding Rock Under Groundwater Conditions
## 1 Introduction  
With the rapid development of infrastructure construction in China, the safety issues of tunnel projects under complex geological conditions have increasingly come to the forefront [1, 2, 3, 4]. Groundwater, as a critical factor influencing the stability of tunnel-surrounding rock [5, 6], has a complex distribution in strata and is highly unpredictable [7, 8]. The interaction mechanisms between groundwater and surrounding rock have long been a key research focus in rock mechanics and engineering [9, 10]. Groundwater significantly impacts tunnel-surrounding rock by softening the rock, reducing rock mass strength, and altering the stress state of the surrounding rock, leading to deformation and failure [11, 12, 13]. During tunnel excavation, groundwater can induce deformation and failure of tunnel-surrounding rock, resulting in severe engineering accidents [14; 15]. Groundwater, through seepage, alters pore pressure in the surrounding rock, thereby influencing its mechanical properties and increasing the risk of rock deformation or collapse [16; 17]. The seepage of groundwater can cause variations in the temperature distribution of surrounding rock, further affecting its mechanical performance and tunnel stability [18]. Chemical reactions between groundwater and surrounding rock, including dissolution and chemical erosion, can alter rock chemistry, affecting its mechanical properties and reducing its load-bearing capacity and deformation resistance [19; 20]. Additionally, tunnel excavation also impacts the groundwater system [21]. Tunnel excavation disturbs the original geological structure, altering the flow paths and permeable channels of groundwater. This can lead to an increase or change in groundwater seepage, affecting tunnel stability and negatively impacting the surrounding ecological environment [22]. During excavation, the decline in groundwater levels may lead to further unloading of the surrounding rock, exacerbating its deformation and instability [5; 23]. Additionally, tunnel excavation may increase the risk of groundwater inrush. This not only threatens construction safety but may also damage the surrounding geological environment [24]. To address the complexity of groundwater development, scholars worldwide primarily use two research methods: field monitoring and numerical simulation. Numerical simulation offers advantages such as being unrestricted by site working conditions and space, providing repeatability and adjustability, making it suitable for analyzing extreme conditions [25; 26; 27]. [PERSON] et al. [28] conducted numerical simulations to investigate the influence of groundwater on the stress distribution of tunnel-surrounding rock, demonstrating that groundwater significantly reduces rock shear strength and increases deformation risks. [PERSON] et al. [29] combined indoor experiments with field monitoring to demonstrate that water inrush significantly reduces the shear strength and elastic modulus of loess, increasing its compressibility. Field monitoring offers high accuracy, real-time observation capabilities, and the ability to validate numerical simulation feasibility, making it applicable in most scenarios. [PERSON] et al. [30] combined field monitoring data with numerical simulation technology to conduct a detailed analysis of settlement characteristics under groundwater influence, proposing a dual-effect mechanism of groundwater on rock deformation. [PERSON] et al. [31] combined indoor experiments with field monitoring to study the impact of groundwater on tunnel rock permeability, showing that groundwater seepage further accelerates rock softening effects. [PERSON] et al. [32] conducted field monitoring to analyze the deformation patterns of deep shafts at different construction stages, proving that groundwater pressure and rock mechanical properties are the primary factors influencing shaft deformation.