# Evaluating the Effects of Deep Excavation on Nearby Structures Through Numerical Simulation
## 1 Introduction  
Land is scarce in many urban areas. For new development projects or the urban renewal of old buildings, construction sites are often surrounded by numerous neighboring buildings. To maximize land use efficiency, buildings are often developed with higher stories and deeper excavations. As such, deep-foundation excavation has become a critical issue. Without proper planning and design in advance, and without stringent quality control and monitoring during construction, it is easy to cause engineering disasters, and minor oversights can lead to damage to neighboring properties. Therefore, deep-foundation excavation projects must be handled with caution. Given that many current deep-foundation excavation projects primarily use the sequential excavation method, this study focused on this method as the simulation target. Utilizing a three-dimensional finite element analysis program (Plaxis 3D, 2017) to analyze the impact of neighboring buildings on deep-foundation excavation. During the design phase, simulations of loading on neighboring buildings are often limited to ground surface loading models, without considering the effects of the depth of underground structures. This might lead to inaccuracies in design. This analysis is based on geological drilling data, diaphragm wall support data, and empirical formulas for the soil elastic modulus. Field monitoring data and numericalsimulation results were compared to validate the model. Actual case model parameters were used to establish relative positions of neighboring buildings and excavation sites, exploring various types of neighboring buildings and their positions to assess their impact on subsurface settlement. Consequently, significant concerns arise regarding the environmental impacts of nearby excavation activities [1; 2; 3; 4; 5; 6]. The behavior of excavation pits is influenced by various factors such as hydrogeological conditions, support types, and geometric configurations. Over time, structural earth pressures can change and soil strength can diminish due to creep [7]. These changes and ground depletions result in ground movements around the excavation site, exerting direct forces on nearby structures. The extent and distribution of ground displacement resulting from excavation are primarily influenced by soil properties, the dimensions of the excavation, the types of walls and support systems employed, and the construction methodology [8]. An inadequate design of excavation retaining structures and ineffective construction practices can lead to significant failures and considerable financial losses [9; 10]. Therefore, it is essential to manage the impacts and deformations associated with excavation to ensure the safety and stability of the excavation site [11; 12; 13; 14; 15; 16]. [PERSON] and [PERSON] research [17] identified three deformation patterns in diaphragm walls during excavation: cantilever displacement, deep lateral inward displacement, and a combination of both. Their study revealed that different soil types, including hard clay, residual soils, and sandy soils, lead to varying ground surface settlements. [PERSON] et al. [18] discussed how the location of maximum lateral displacement in diaphragm walls shifts with excavation depth, moving closer to the excavation face as digging progresses. [PERSON] and [PERSON] [19] used finite element analysis to identify the critical factors affecting deep-excavation wall deformations, with their findings validated through field monitoring. [PERSON] [20] applied the Mohr-Coulomb model (MCM) to predict the lateral movement of diaphragm walls but found it less effective for predicting surface settlements. By incorporating soil parameters from laboratory and field tests into both the small strain model (SSM) and the hardening soil model (HSM), the analysis improved the predictions of lateral wall movements and surface settlements. Recently, numerical analysis has become the cornerstone of design for most deep excavation projects.