تحليل لرزه‌يي سپر مهارشده با پاي مفصلي در خاك دانه ‌يي به روش شبه استاتيكي

SEISMIC ANALYSIS OF ANCHOR SHEET PILE WITH A GRANULAR SOIL USING PSEUDO-STATIC APPROACH

اين نوشتار با توسعه‌ي روش استاتيكي كولمب، روشي نوين براي تحليل لرزه‌يي سپر مهارشده در خاك دانه‌يي با پاي مفصلي را براساس روش شبه‌استاتيكي ارايه مي‌كند. به‌منظور بررسي اثر زاويه‌ي‌ اصطكاك داخلي خاك، شتاب قايم و افقي زلزله بر ميزان و نحوه‌ي توزيع فشار محرك و مقاوم وارد بر سپر و ميزان لنگر خمشي بيشينه‌ي ايجادشده در آن، عمق مدفون موردنياز و نيروي كششي مهار، مطالعات پارامتري نسبتاً مفصلي انجام شده است. نتايج حاصل نشان مي دهند كه افزايش زاويه‌ي اصطكاك داخلي خاك و شتاب افقي زلزله بر عملكرد سپر و پارامترهاي موردنظر تاثير قابل‌توجهي دارند، درحالي‌كه اثر شتاب قايم زلزله به‌ خصوص براي مقادير كم از شتاب افقي در ارزيابي اين‌گونه سپرها قابل‌توجه نيست.

Sheet piles have been commonly used in the construction industry since early in the last century. They are used in a wide variety of both temporary and permanent building applications, including retaining walls, slope stabilization, seepage control barriers, sea walls, dock and harbor works, permanent foundations and ground reclamation work. Since the understanding and knowledge of designing under static and dynamic loads (i.e., earthquake) need to be increased, this paper presents the seismic analysis of an anchor free earth support sheet pile in granular soil by developing the static Coulomb method in the framework of the pseudo-static method. Parametric studies quantify the effects of the soil internal angle of friction (?) and the horizontal and vertical seismic coefficients (kh and kv) on the active and net passive pressure distribution on the sheet pile, the maximum bending moment and depth of penetration of the sheet pile and, also, the tension force in the anchor. The results indicate that an increase in the soil internal angle of friction and the horizontal seismic coefficient can significantly influence the performance of the sheet pile. The effect of an increase in horizontal seismic coefficient on the parameters above is more effective for the low values of soil internal angle of friction (? < 30?°) than for high values of soil internal angle of friction (? > 35°). Likewise, the effect of vertical seismic coefficient on the performance of the sheet pile is not significant, particularly for low values of horizontal seismic acceleration. On the other hand, the vertical seismic coefficient on the behavior of the sheet pile is more remarkable for the high value of horizontal seismic coefficient (kh?0.2) and poor quality backfill (? < 30°?). Overall, in practice, the use of incompetent backfill material (? < 30?) and also a strong earthquake (kh?0.2) is infrequent. Consequently, considering the undesirable effects of the vertical seismic coefficient in combination with the horizontal seismic coefficient may possibly be ignored.