## 2 Methodology  
The geology and geotechnics of southeast Madrid, where volumetrically unstable clayey deposits have been described, requires techniques that allow for the use of this type of material; always with an adequate analysis of the problems associated with the particular linear infrastructure work or with the construction of buildings. This article is structured as follows (Figure 1). Firstly, the geological environment is described, establishing a sedimentary setting and a detailed mineralogy analysis of the tertiary clay. Secondly, a geotechnical characterization is done, based on a quantitative description of the basic properties (soil quality indicators), which, along with grain size and mineralogy composition, will determine the geotechnical classification. The information obtained is synthetized to reflect the most significant values for each quantified characteristic. Then, a detailed description of the methodology developed is offered. Finally, a methodology is established in order to contribute to the improvement and development of new techniques that have been proven valid for this type of land, and, the future fields of application are described. Figure 1: Methodology diagram. In order to understand the construction procedures to be used in new areas of development, the geological characteristics of this sector of Madrid's river basin must be established, focusing on the study of the clayey and plastic transition deposits as well as on the processes originating in them. Following this line of reasoning, different deposition systems will be reconstructed taking into account the basin fill, and, along with this, the syngenetic conditions that will mark the final distribution of the deposits. In general, the basin fill enters in a model of mixed continental endorheic basin deposition, where the deposits outcrop to the inside, creating the classical facies distribution outline with edge, intermediate, and central areas with various changes in facies [7; 8]. The larger grain size materials that are deposited on the edge of the river basin are predominantly granitic, this gives rise to sandy deposits and smaller size detritus which are transported a longer distance to where they will logically be distributed according to the energy in the environment and the size of the particle (Figure 2). There is no energy in the middle of the basin, and water stagnates to flood a large area which gives rise to a lacustrine environment where chemical precipitation is abundant. In principle, this very simple and classical outline allows for the establishment of spatial distribution of the different geological formations, which, due to their syngeneic characteristics, occupy very specific positions in the river basin [9]. As will be seen, these geological formations will have key geotechnical repercussions. It also enables us to be able to differentiate, thanks to the existing sedimentary discontinuities, three major deposition sequences: an upper, intermediate, and lower deposition sequence; the last two are present in the Southeast of Madrid. The lower deposition sequence is represented by predominantly evaporite deposits (gypsum) where detritus materials of a predominantly clayey nature interdigitate to a greater or lesser extent. The following can be differentiated, massive gypsum, folded gypsum, and clay with gypsum along with other units of lower entity. Regarding the sediment, it corresponds to native syngenesis which is typical of the central part of the river basin, and the deposition environment corresponds to the lacustrine areas. The intermediate deposition sequence found on this part largely consists of evaporite deposits (gypsum). It is represented by a series of predominantly clay sediments that are lithologically quite heterogeneous and are comprised of brownish-green clay with whitish marl and marl-dolomite, beige spatiolite clay, brown smectite clay, and folds of purplish opaline silica.