بررسي آزمايشگاهي تاثير آهك در روند خود ترميمي و واگرايي خاك هاي رسي (مطالعه موردي: سد گرديان)

Experimental Study of the Effect of Lime in the Process of Self-Healing and Dispersivity of Clay Soils (Case Study: Gordyan Dam

لايه هاي رسي متراكم از متداول ترين لايه هاي نفوذ ناپذير به شمار مي روند. واگرايي و ترك خوردگي لايه هاي رسي از جمله عواملي هستند كه كارايي خاك رُس را كاهش و ضرورت تثبيت خاك رُس را اجتناب ناپذير مي نمايد. خاصيت ترميمي خاك رُس و اهميت خودترميمي ترك ها در لايه هاي رسي به عنوان يكي از شاخص ها و ويژگي هاي مثبت رُس در چند سال اخير مورد توجه محققين بوده است. در اين تحقيق عملكرد خودترميمي و واگرايي لايه هاي رسي در اثر افزودن آهك بر روي خاك رُس مصالح قرضه گرگر در سد گرديان مورد ارزيابي و بررسي قرار گرفته است. بدين منظور براي دو نمونه خاك واگرا با افزودن آهك ساختماني به ميزان 1 ،0/5 ،0/25 و 2 درصد و انجام آزمايش هاي هيدرومتري مضاعف، حدود اتربرگ و پين هول روند واگرايي و خودترميمي مورد بررسي قرار گرفت. نتايج حاصله نشان داد كه با افزودن 1درصد آهك به خاك رس، دامنه خميري افزايش يافته و دبي خروجي آزمايش پين هول براي هر دو نمونه 28 درصد و قطر نهايي نمونه براي هر دو خاك 67 درصد كاهش پيدا كرده كه اين حاكي از بهبود روند خودترميمي وكاهش واگرايي و تبديل شدن به خاك غير واگرا مي باشد.

Compact clay layers are one the most impermeable layers. Dispersivity and cracking of clay layers are among the factors that reduce the efficiency of clay and necessitate clay stabilization. Clay healing properties and the importance of self-healing cracks in clay layers as one of the characteristics and attributes of clay in recent years have been studied. In this research, the self-healing performance of clay layers due to the addition of lime to the clay materials of Gordyan dam borrow pit (Gargar) was investigated. For this purpose, two dispersive (S2 and S3) soil samples (ND3 and ND4) were investigated by adding lime to the extent 0.25, 0.5, 1 and 2%, and Double Hydrometer, Atterberg limits and Pinhole tests of dispersivity and self-healing were investigated. The results showed that by adding 1% of lime to clay, the range of plasticity index increased and the discharge rate of the pinhole test for both samples was 28% and the final diameter of the sample for both samples decreased by 67%, indicating an improvement in self-healing process and a reduction of dispersivity and becoming non-dispersive soil (ND1). The results also showed that pinhole testing has reliable and more accurate results than other tests in determining soil dispersivity.