تحليل رفتار شمع– ستون ها تحت بار جانبي با درنظرگرفتن اندركنش خاك و سازه

Investigation of Lateral Loaded Mono-Pile Behavior Considering Soil and Structure Intera

در اين نوشتار، عوامل موثر در رفتار بار- جابه جايي شمع- ستون مانند: مقاومت خاك، نسبت هاي طول آزاد به طول مدفون، و قطر شمع- ستون مورد بررسي قرار گرفته است. پاسخ بار-جابه جايي مدل شمع- ستون واقع در خاك، با پاسخ يك ستون با انتهاي گيردار بدون حضور خاك مقايسه شده است، تا طول موثر ستون معادل (طول ستون به اضافه‌ي مقداري از طول شمع به نام عمق گيرداري) تعيين شود. تحليل ها نشان داده‌اند هر چقدر نسبت طول آزاد به طول مدفون افزايش يابد، شمع- ستون رفتار صلب تري از خود نشان مي دهد. افزايش عمق مدفون و قطر شمع- ستون و مقاومت خاك منجر به افزايش ظرفيت باربري شمع-ستون مي ‌شود، با اين حال در هر شرايط عمقي وجود دارد كه بعد از آن، افزايش طول مدفون تاثيري در مقدار باربري ندارد. در خاك ماسه ‌يي متراكم با افزايش طول آزاد شمع-ستون، عمق گيرداري كاهش مي يابد، ولي در خاك ماسه ‌يي سُست روند خاصي ملاحظه نشده است.

In this paper, the behavior of laterally loaded mono-piles was investigated considering soil and structure interaction, and using numerical modeling. The numerical model was, at first, verified using large scale experimental test results and some analytical methods. Then, some sensitivity analyses were performed and the effects of parameters, such as free to embedded length ratio of the mono-pile, diameter of the pile, soil strength and etc., were investigated. Finally, the response of the laterally loaded mono-pile and soil system was compared with an end fixed column to find an equilibrium length for the column to have the best fit response with the mono-pile and soil system. The verification analysis of numerical modeling showed good compatibility with the large scale tests results and analytical methods. Also, the sensitivity results showed that increasing the free to embedded length ratio and diameter of the mono-pile and reducing soil strength result in the rigid behavior of the mono-pile. Increasing the soil strength, pile diameter and embedded length of the mono-pile increases the mono-pile lateral bearing capacity. However, there is an embedded length, as critical depth, subsequent to which, the mono-pile lateral bearing capacity becomes constant. Comparing the load- displacement response of the mono-pile and soil system with an end fixed column showed that it is possible to replace the mono-pile and soil with a column having an equiblibrium length as its initial length plus a pert embedded length (called depth of fixity). The amount of depth of fixity is suggested to be 6 to 10 times the pile diameter, without considering soil and pile conditions. The depth of fixity depends on the free length and diameter of the mono-pile and soil strength, so that, increasing the free length of the mono-pile results in an increase in the depth of fixity in dense sand soil. However, there is not a specific trend in the loose sand soil.