تحليل عملكرد ديواره‌ي ميخ‌كوبي در تثبيت ديواره‌ي گودبرداري هاي عميق براساس سطوح خرابي سازه هاي مجاور گود

Performance Analysis of Deep Soil Nail Walls Based on Excavation-Induced Damage

تخمين و ارزيابي آسيب هاي وارده به سازه هاي اطراف گود به‌واسطه‌ي جابجايي هاي زمين، از مسايل حايز اهميت در ملاحظات مربوط به طراحي سيستم ميخ‌كوبي در مناطق شهري است. اين مسيله در صورت حضور سازه هاي با عمر زياد و يا با درجه‌ي استحكام پايين در مجاورت گود اهميت بيشتري دارد. به‌واسطه‌ي نبود داده هاي مستند و دقيق و همچنين تعدد متغيرهاي تاثيرگذار در پاسخ سازه ها به جابجايي هاي ناشي از گودبرداري، در حال حاضر معيارهاي تخمين درجه‌ي آسيب سازه هاي مجاور گود، بسيار معدود و در بسياري از موارد به‌واسطه‌ي محدوديت هاي موجود كاربردي نيستند. در اين پژوهش سعي شده است با تكيه بر10 مطالعه‌ي موردي و همچنين بهره گيري از آناليزهاي عددي و احتمالاتي، ضمن تحليل عملكرد سيستم ميخ‌كوبي در تثبيت ديواره‌ي گودبرداري هاي عميق، به ارايه‌ي سطوح خرابي سازه هاي مجاور گود براساس تابع پتانسيل خرابي پرداخته شود. سطوح خرابي پيشنهادي در اين نوشتار، نشانگر ميزان خرابي محتمل در سازه‌هاي مصالح بنايي مجاور ديواره هاي ميخ‌كوبي‌شده، با توجه به فاصله‌ي قاب سازه از بر گود و به‌ازا بيشينه‌ي مقادير تغييرشكل افقي ديواره‌ي گود است.

Response assessment of buildings to excavation-related ground movement is an important design aspect of support systems in urban areas. This is even more important if the adjacent structure be old or have low strength parameters. Frame distortion and crack generation are signs of building damage by excavation-induced ground movement, and are a challenge in projects involving deep excavations. These highlight the importance of the evaluation of building responses in excavation projects. The aim of estimation and evaluation of building response is to establish limiting criterion for excavation support system design to certify structural safety against undesirable damage. Thus, the limiting criterion prepares a framework to determine the damage level of buildings based on excavation induced ground movement. Limiting criterion is also known as damage criterion or damage models. Damage models are too practical before design progress of nailing wall. Based on the uncertainty of data from excavation projects and the variability of the many factors that contribute to the response of nearby structures, existing damage models are rare and generally need special instrumentation of the excavation wall and nearby structures. So, they cannot prepare a simple framework for use in practical situations. This paper describes a study of building responses to excavation-related ground movement and provides a procedure for damage assessment of buildings near excavation projects. This study uses field data based on 10 case studies and calibrated FEM models, in addition to probabilistic analysis, to establish new simple damage criteria for design consideration of excavations supported by a soil nail wall technique. The presented damage model simply relates the damage level of the structure to the maximum displacement of the excavation wall. The deflection mode of a soil nail wall for two types of nail distribution and 23 types of soil, in addition to the results of free field analysis, are also topics presented in this paper to achieve the damage model.