Assessment of the Effect of Pre-stressing Steel Strut on Displacement of the Diaphragm Wall and the Soil

In this research, the effects of pre-stressing steel struts on horizontal displacement of the diaphragm wall and settlement of the soil behind the wall are investigated utilizing the FLAC software through implementing the finite difference method and Mohr-Coulomb behavior model. A 20m diaphragm wall with 80 cm thickness and the Young's Modulus of 22000 MPa and the Poisson ratio of 0.15 is modeled. The final depth of excavation is 12 m and the properties corresponding to the concrete stiffness of the diaphragm wall, depth of excavation and arrangement of the struts are taken from (Freiseder and Schweiger, 1998). Modeling is done for 3 types of soils with different modulus of elasticity values including 3 pre-stressing forces and 3 different water levels, so totally 27 models were designed and analyzed. For this purpose 3 types of sandy soils with a Poisson ratio of 0.30 are used for modeling. The soils properties are taken from Chowdhury et al. (2013) and are given in Table 1. In this table 'φ denotes the internal friction angle and C 'denotes the soil's cohesion. This research is conducted for 3 water levels; at the ground level and for depths of 4 and 8 m below the ground level. The models are analyzed for three cases namely non-pre-stressing and pre-stressing forces of 200 and 400 KN.