تثبيت خاك با آهك جهت بهبود پارامترهاي مقاومت برشي و كاهش پتانسيل رمبندگي خاك، مطالعه‌ي موردي: جاده‌ي ياسوج- يزد

Soil Stabilization with Lime for the Improvement of Strength Parameters and Reduction of Potential Collapse

كشور ايران در زمره‌ي كشورهايي قرار گرفته است كه خاك‌هاي رمبنده دارد و در صورت عدم شناسايي اين خاك ها، اگر سازه، راه، و يا خطوط ريلي روي آنها احداث شود، مي تواند در اثر اشباع‌شدن خاك، مشكلات قابل توجهي را ايجاد كند. در اين پژوهش به بررسي و مطالعه‌ي آزمايشگاهي تثبيت خاك و كاهش رمبندگي و افزايش خصوصيات مقاومت برشي آن با استفاده از تزريق آهك پرداخته شده و سپس رمبندگي خاك مورد تزريق و خاك در حالت طبيعي مورد مقايسه قرار گرفته است. نتايج نشان مي دهد كه تزريق آهك باعث كاهش پتانسيل رمبندگي خاك مي شود. همچنين پارامترهاي مقاومت برشي خاك پس از تزريق بهبود يافته و مقدار بعد از تزريق تقريباً 15/2 برابر شده و پارامتر ، 62/1 برابر شده است، كه با توجه به ثابت‌بودن تنش ها در هر دو آزمايش خاك در حالت طبيعي و خاك تزريق‌شده با آهك، افزايش زاويه‌ي اصطكاك داخلي و كاهش چسبندگي خاك را به همراه داشته است، كه نشان از بهبود رفتار خاك پس از تزريق است.

Iran is a country with unstable soil. If soil classes, characteristics and structures are not identified properly, railroads or roads that are to be built can face significant problems, as the soil becomes saturated. Some soils in our environment cannot undergo the normal tension they encounter, and by the slightest increase in the ratio of humidity, will encounter high settlement. These kinds of soil, mainly found in hot and dry regions, like deserts, are called collapsible soils. In this article, to correct the soil of these regions, some items, like the behavior of lime injected materials in the presence of clay in cementitous soil, for creating suitable adhesion among grains and micro-silica as porosity filling materials, are studied separately. In this study, to investigate and stabilize soil, reduce collapse potential and increase its strength properties, the use of limestone injection technology has been considered. Then, the collapse potential of the soil under injection has been compared with that of natural state soil. The results indicate the good performance of the injection method compared with existing methods. These results show that the injection of lime will reduce the potential for soil collapse. The soil shear strength parameters improved after injection, and the value of ?u after injection reached an amount of approximately 2.15 times the initial internal friction angle. Parameter ?ʹ increased up to 1.62, which, considering the fixed amount of tension in both tests on soil in normal state, and the injected soil, was associated with an increase in internal friction and a reduction in the adhesion of soil grains. The results of field and laboratory tests reveal that according to clay cementation among soil grains on site, the injection of lime would result in a considerable reduction in the collapsibility potential of soil in a saturated condition. Therefore, it can be suggested as a suitable solution.