Abstract:

A grouting curtain was designed and performance based on GIN method for the first time in Siahbishe pumped storage project Iran. These concrete face rockfill dams are located 125 kilometer far from Tehran to north. Foundation rock mass contain an intermittent of siltstone, shale and sandstone (Shemshak Formation). Considering that GIN method often guiding for water tighten of rock fissures (tight to open range), but in this case the abovementioned method is using for open to very open fractures (opening; 10 ~100 mm) with some changing of its method statement and flowchart that means an evaluated method for tension zones. Foundation treatment of upper dam was starting with standard method based on test panels in the riverbed that has encountered a compressive rock mass with tight to open fissures, then during raising the level (specially in right bank) discontinuity condition transitionally changed to tensioned fractures. It was necessary improving this method as per actual condition; therefore in five numbers of 12 meter Panels (from 41 to 45) the new (evaluated) method was done, details of the grouting work such as, row, arrangement, effective pressure, grout mix, lugeon (water pressure test), additives, GIN number, Grout take and flow rate will illustrational describe in the main text. Author tries to present a way to find optimum GIN, its typical curve and new executive flowchart in this paper. Also it generally recommended regards to classic method, due to technical and economical advantages.

Introduction

Gin method for grouting to rock mass, the first one via Lombardi & Deer 1993 presentation. The Grouting Intensity Number (GIN) method for cement grouting of rock masses is derived and presented. The main features unique to the method are:

  1. a single, stable grout mix for entire grouting process (Water: Cement ratio by weight These to 0.8:1) with super plasticizer to increase penetrability.

  2. a steady low to medium rate of grout pumping which, overtime, leads to a gradually increasing pressure as the grout penetrates further into the rock fractures.

Traditional grouting it is one special instance of methods GIN when GIN ≥ Pmax,Vmax. The grouting of rock masses with cement slurries to improve their mechanical and hydraulic properties is a well established practice in civil engineering. This method usually in projects' of dam acceptance for watertight and consolidation grouting but disacceptance for grouting in soil foundation and carstices Lombardi 1996.in traditional grouting is belief that grouting start with suspension near water until arrive thick grouting fine cracks thin grout easily than thick grout penetrate while relevant equation Fell et all 2006 grout penetration to joints dependant to size grained cement. Also this theory that thick grout new, washing the thin grout old and replaced it is not correct Houlsby1982. In grouting by method GIN with using of superplasticizers can regulation viscosity and cohesion thick grouted. Bremen1977 believer that Bentonite is one reduction of bleeding not one plasticizer Experience in several countries at major hydroelectric projects indicates the method to be technically and economically effective.

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