# Evaluating the Effects of Deep Excavation on Nearby Structures Through Numerical Simulation
## 3 Numerical Simulation Analysis and Verification
### Numerical Simulation Model and Input Parameters
#### 3.4.1 Adjacent Building and Road Loadings  
In this study, the estimated load per square meter for each floor of neighboring buildings was based on the static and live load specifications of Taiwan's building technical regulations. The dead load and live load were 5.3 kPa (550 kgf/m\({}^{2}\)) and 1.9 kPa (200 kgf/m\({}^{2}\)), respectively. Using the load combination of the reinforced concrete design standards, 1.2 D + 1.6 L, the estimated load for neighboring buildings was 10.6 kPa.  
The structure was modeled as a hollow cube unit with a span of 10 m and floor height of 3 m. For a floor slab thickness of 20 cm, the wall thickness of the hollow cube was also 20 cm, and its weight was calculated as (10 \(\times\) 10 \(\times\) 0.2 + 3 \(\times\) 10 \(\times\) 0.2 \(\times\) 4) \(\times\) 2.4 = 105.6 t. Thus, the load per square meter per floor is: 105.6 t/10 \(\times\) 10 m\({}^{2}\) = 1.056 t/m\({}^{2}\) per floor \(\approx\) 9.81 kPa (1 t/m\({}^{2}\)) per floor. For modeling, a load of 1 t/m\({}^{2}\) per floor is used.  
Therefore, for subsequent modeling, the neighboring buildings were represented as follows: 4-story buildings were modeled as a 3.5 m thick slab, 5-story buildings as a 3.8 m thick slab, and 12-story buildings as an 8.125 m thick slab.  
The surrounding roads and sidewalks were estimated to have a load of about 9.81 kPa (1 t/m\({}^{2}\)) considering the subgrade composition, reinforced concrete, asphalt concrete, and live loads from vehicles.  
The neighboring buildings within a distance of five times the excavation depth were as follows: on the east side, there was a 12-story community building with two basement levels, an estimated basement wall thickness of 0.8 m, and a depth of 8 m. On the north side, there is a four-story street house with one basement level, an estimated basement wall thickness of 0.4 m, and a depth of 4 m. On the west side, there was a four-story apartment with one basement level, an estimated basement wall thickness of 0.4 m, and a depth of 4 m. On the south side, there was a five-story apartment community with one basement level, an estimated basement wall thickness of 0.4 m, and a depth of 5 m, as shown in Figure 3.  
Figure 2: PLAXIS 3D geological stratification model diagram.  
In PLAXIS, the interfaces are used at the junction between the diaphragm wall and the soil. Interface elements have zero actual thickness but have a virtual thickness affecting elastic deformation. The default thickness factor in PLAXIS is 0.1. When activated, the interface is impermeable; when frozen, it is permeable. The interface for underground diaphragm walls should be set as impermeable and the strength reduction factor must be set to rigid (\(R_{\mathit{inter}}=1\)). For diaphragm walls around foundations, an extended interface should be established at the bottom end, divided into positive and negative interfaces, both set to rigid (\(R_{\mathit{inter}}=1\)).  
In previous deep-excavation analyses, neighboring buildings and roads were modeled using surface loading. To compare this with the method used in this study, an additional model was created where the neighboring buildings were analyzed using surface loading. The load of the neighboring buildings was applied to the ground surface, as shown in Figure 4, and converted into ground surface load calculations, as shown in Table 2.  
Figure 4: Model with surface loading for the neighboring buildings.  
Figure 3: PLAXIS 3D: (**a**) elevation view; (**b**) plan view.