Statistical and Empirical Prediction of Compression Index for Collapsible clayey soils

پيش بيني تجربي و آماري شاخص فشردگي خاك هاي رسي فروريزشي

The sudden differential settlement of soil caused by collapsibility phenomenon can be reduced using improvement methods that mainly involve inundation. However, what happens then in the inundated collapsible clay soil is the settlement resulted from the consolidation phenomenon, which is caused by structure overload. Thus, the present study aimed to propose models for rapid estimation of consolidation settlement of such soils. Generally, compression and swelling indices resulting from consolidation test are used to calculate the consolidation settlement. In order to determine the soil s compression index in this study, 122 standard consolidation tests were performed on the undisturbed samples of collapsible clayey soil and then compression index as well as other features of the soil were extracted. After statistical analyses were completed on data, models associated with physical properties of soil were obtained. To conduct a comparative analysis of results obtained for the compression index and other models, statistical techniques such as analysis of variance (ANOVA) were used. Three univariate and multivariate models for physical properties of soil were achieved through data and statistical analyses. The results indicated that there is higher correlation between the soil compression index and the initial void ratio compared to between other soil physical features. The results of this study including estimation and calculation of consolidation settlement of foundations can initially provide relatively good knowledge of all kinds of settlements for structure designers; so, resulted from collapsibility and consolidation settlement so they could select the most suitable foundation system.

پديده فروريزشي در خاكهاي رمبنده را مي توان با روش آب اندازي بهسازي نمود. بهر حال بعد از وقوع نشست ناشي از پديده فروريزشي با پديده نشست تحكيمي مواجه هستيم. هدف اصلي اين تحقيق ارائه مدل هايي براي تخمين سريع نشست تحكيمي مي باشد. نشست تحكيمي عموما با محاسبه شاخص فشردگي خاك تخمين زده مي شود. به منظور تعيين شاخص فشردگي خاك رسي تعداد 122 آزمايش تحكيم استاندارد بر روي نمونه هاي دست نخورده خاك انجام گرديد. سپس با روش آماري و استفاده از آناليز واريانس وابستگي شاخص فشردگي به ساير كميت هاي فيزيكي خاك مرتيط گرديد. در اين تحليل يك نوع رتبه بندي نيز براي روابط همبستگي موجود نيز ارائه شد. نتيجه اين تحقيق براي انتخاب مناسبترين نوع پي با توجه امكان محاسبه سريع نشست تحكيمي در پروژه ها كمك شاياني مي نمايد.