## 5 Discussion
The other category is \(S_{w}\)-related regulations, e.g., the regulation for the Wuhan area proposed that (0-3)\(S_{w}\) is the primary influence zone with a settlement of (0.73-1)\(H_{m}\), (3-10)\(S_{w}\) is the secondary influence zone with a settlement of (0.45-0.73)\(H_{m}\), and (10-30)\(S_{w}\) is the minor influence zone with a settlement of (0.12\(\sim\)0.45)\(H_{m}\)[76]. While the technical specification for foundation pit support in the Shenzhen area provides that (0-1)\(S_{w}\) is the primary influence zone, (1-3)\(S_{w}\) is the secondary influence zone, and (3)\(S_{w}\) is the minor influence zone [77]. Thus, the zoning is regional empirical, and there is no unified theory for direct application. Based on the comparison with the settlement curves of the probabilistic analysis in this study, it is found that the influence range of settlement is independent of the spatial variability of the parameters, and the partitioning is more consistent with the principle of the literature [76]. It is quite puzzling that there is such a dramatic discrepancy between the Wuhan area and the Shenzhen area as mentioned above. It may be due to the close hydraulic connection between groundwater and surface water, such as the Yangtze River in the Wuhan area, with sufficient groundwater recharge and correspondingly greater funnel-shaped groundwater surface and consequently more excellent settlement coverage. In contrast, the Shenzhen area has a narrower river basin and less extensible stratigraphy, resulting in a narrower pumping area and settlement coverage. Hence, it is concluded that the influence range of draining and ground settlement are identical. For an excavation with a relatively homogeneous stratum, ground settlement is predominantly controlled by the drawdown. Meanwhile, the duration, volume, season of pumping, and the hydrogeological boundary of the excavation site also affect the shape of the depression cone formed by draining. In practical engineering, ground settlement is also related to the distribution of strata, compressibility, the thickness of the compressed layer, and surrounding buildings. To summarize, it is difficult to derive a universally applicable partitioning regulation, and it is required to integrate the above considerations. There are still some issues for the study that requires to be examined in further research. Firstly, only two independent spatial variable parameters were taken as a random field in the study, but actually, there are more parameters (e.g., permeability, stiffness, strength, etc.) and scenarios could be expected to be taken into account as random variables in the realistic situation. The correlation between parameters can be modeled through the Copula approach [78; 79] or other methods [80]. Secondly, this study addressed a simplified model without considering the complex stratigraphic sequence and varied hydraulic boundary conditions. Practically, field-scale exploration and modeling technology have advanced dramatically currently [81]. Further studies can be implemented by refining the analytical model to explore the settlement pattern. Meanwhile, the unsaturated soil elastoplastic extended Cambridge principal model [82] can be introduced to perform the unsaturated hydro-mechanical coupling analysis during the draining and excavation.