This research describes the technique of diaphragm wall as a retaining solution and the calculation methods for the reaction forces of struts used for supporting a wall. In addition, the procedure to obtain earth pressure values on the wall and their distribution under the Chilean Norm NCh.3206 and the German recommendation EAB are indicated. The structural elements and the geotechnical characterization of a strutted diaphragm wall with struts on three levels, built in the region of Valparaíso, Chile, are studied in order to obtain the strut reaction forces by using theoretical and numerical models. Finally, results are shown, comparing graphically the data recorded in-situ and values obtained through theoretical and numerical modeling for strut reaction forces.