Determining Radius of Cement Grouting Zone for Stabilization of Alluvial Sediments around Line 1 Tunnels of Tehran Subway

Cement grouting is one of the effective ways to soil rehabilitation and improve the of strength properties of the soil. In this way, the influence of cement slurry with concentration and specific pressure to the pores, holes and gaps in alluvial soil, contributes to consolidating and stabilizing the soil around tunnel. Evaluation of soil permeability after grouting, brings up as one of the successfully method of grouting. This point is very important for tunnel’s water tightness (institution of watertight facing).In this paper, the current theoretical methods in determining radius of grouted zone are described and new method based on dimensional analysis has been developed and presented. In fact the result of this approach is compared with existing criteria in estimating of the effective radius of grouted zone in alluvial soils. Consideration of soil permeability parameter is the asset of this method. Also existence of this parameter, permit to the grouting plan to insert appropriate permeability and basically we can calculate the effective radius of cement grouting. Finally, the result is compared with the in-situ data obtained from sampling locations along line 1 tunnels of Tehran subway.