## 2 Methods
The scopes of the applied construction protections are different and depend on a specific situation [20; 21; 22]. The most common external protections are in the form of a diaphragm wall, i.e., a Berliner wall (lagging wall), a sheet pile wall, and a retaining column wall made by jet grouting and mixed technologies (Figure 1). The stability of deep excavation casing made with one of these technologies is additionally ensured by bracing struts, ground anchors (Figure 2), or the floor slabs of underground storeys [23]. If there are relatively small spans, the bracing struts can be made of wide-flange I-sections. Larger spans require bracing that uses steel tubes with a diameter of 400-800 mm [24]. In addition to the compressive forces and the bending moment derived from excavation support load, very large impact on the axial forces comes from the thermal effects. In order to determine the real effect of temperature on the bracing strut, the susceptibility of their props needs to be determined. Figure 1: Various structural solutions for deep excavation support. (**a**) diaphragm wall, (**b**) Berliner wall (lagging wall), (**c**) sheet pile wall, (**d**) retaining column wall made by jet grouting (developed by authors). Figure 2: Structural solutions to ensure the stability of a deep excavation: (**a**) bracing struts, (**b**) ground anchors (developed by authors). In the case when the building structure is not able to transfer these additional loads, it is necessary to design the structure's reinforcement and ground foundation [25]. Various methods can be used to increase the bearing capacity of foundations. One commonly used method is the classical method, which involves the excavating of the foundations followed by the underpinning of them, or the extending of the foundations while assuming that there is no water at the depth of the intended works, with the height of the underpinning not exceeding 3 m.  
The walls of existing buildings can also be reinforced using injection micro piles and statically pressured micro-piles, as well as drill and screw micro-piles, the advantage of which is their high rigidity. These elements are shown in Figure 3.  
Currently, the most common method of strengthening existing building, especially historic ones is underpinning by means of jet grouting injections (Figure 4). Estimating the impact of an excavation on neighboring buildings involves:  
Figure 4: Increasing the bearing capacity of a foundation by means of jet grouting (developed by authors). Figure 3: Additional structural elements that are used to transfer loads from the deeper layers of soil with a higher load-bearing capacity: (**a**) injection micro-piles, (**b**) drill micro-piles, (**c**) screw micro-piles (developed by authors). the determination of the impact range of the excavation (impact zone),
* the determination of the vertical and horizontal displacements of the excavation casing and the adjacent area,
* the determination of the expected horizontal and vertical displacements of adjacent buildings;
* making sure that the expected displacements of existing buildings are lower than their maximum limit displacements. The range of the excavation impact zone is determined with regards to the type of soil and the depth of the excavation. According to various studies presented in the literature, this range is a multiple of the excavation depth H and depends on the type of soil and the excavation casing, as shown in Table 1. The impact zone can also be determined with regards to the shape and width of the foundation of the erected building, the amount of pressure at its base, and the average value of the deformation modulus in the settling soil layer.