公路隧道煙控啟動模式及避難策略之研究-以雪山隧道為例

Abstract

本研究以目前雪山隧道坪林行控中心在火災發生初期、中期、末期時實際操作的煙控模式進行探討，針對危害性較高的火災情境進行研究;現階段雪山隧道發生火災時主要採取煙控的模式為「避難模式」和「排煙模式」，以及「單孔單向」和「單孔雙向」等分類，實際運作模式分為避難模式28種、排煙模式12種共有40種，本研究僅採用單孔單向並配合原4種「避難模式」和6種優化「排煙模式」設計作為煙控最適化設計研究方向。 雪山隧道總計12.9km長度，本研究採用5000m作為全尺寸的模擬，用實際距離設置噴流式風機，而在隧道兩豎井中間假設為最危險的狀況(worse case)作為FDS模擬之主要情境，並假設中繼站發生火災為最危險的情況進行模擬，經測試後發現3個中繼站以第一站的位置較易產生逆煙層，進一步本研究採用原雪隧使用的煙控模式為避難一(Eva1)至避難四(Eva4)四種情境，以不同噴流式風機(Jet Fan)及軸流式風機(Axial-Flow Fan)啟動機制，做為比較。 原設計使用的緊急運轉之避難模式所啟動的風機為上游4組噴流式風機，下游以間隔方式啟動噴流式風機，經過測試，15MW和30MW的火源，用路人在火源上游30m處可以達到安全臨界值前進行避難，但截至目前最嚴重的火災為65MW，則無法進行避難，研究中發現原雪隧使用之煙控模式無法控制排煙，為防止火災發生之煙層擾動，需要遵守上游250m和下游500m的風機不啟動之原則。 為改善原雪隧無法有效控制排煙之煙控模式，本研究採取5種優化設計情境做探討。本研究發現，在火源下游的部份不管有無啟動風機，都會造成避難人員的傷害，所以在安全管理良好的情況下，我們探討火源上游的安全性，以成人和避難弱者步行速度為1.2m/s和0.64m/s，所需避難時間共需205秒和227秒。 在避難模式部分，針對15MW達到安全臨界值的時間下比對，可使人員達到避難，但對於火源30MW和65MW的部分卻是危險的，而雪隧遇到最嚴重的車禍則為65MW的火災類型，所以在這三種火源中，對於上游人員的避難，以情境五是最佳的。 火源上、下游的能見度會較快影響到用路人安全，溫度則為其次，以情境五作為說明，在風機為一樣風量為前提，上游6組、下游4組噴流式風機啟動的情況下，因模式五無產生逆煙層和避難模式有產生逆煙層的時間做比較，避難模式增加了224~259秒的時間，所以減緩了224~259秒煙層下降時間，而下游的部份以能見度最快達到安全臨界值，上游6組、下游4組風機啟動比上游4組、下游4組風機的情境，啟動減少22秒(15MW)、24秒(30MW)、30秒(65MW)往上游避難的時間，因為風機啟動只會加速下游能見度的下降和溫度的上升，但豎井有啟動比沒有啟動增加約11~24秒的避難時間。

The study adopted smoke control modes of actual operation to analysis the hazard of high fire situation while fire occurred on beginning, middle and final stage in emergency control center of Shiue Shan tunnel. At the present stage, while fire occurred in Shiue Shan tunnel, an existing smoke control strategy has been mainly conducted, which divided into "evacuation mode" and "exhaust smoke mode", and " a single hole way " and "two holes–single way ",etc. The actual modes of operation are divided into 28 kinds of evacuation mode, 12 kinds of exhaust smoke modes. This study adopted a single hole way with the original 4 kinds of evacuation mode and 6 kinds of exhaust smoke mode as a smoke control optimum design study direction. There are 12.9 km length totally in Shiue Shan tunnel, this study adopted 5000 m as a full-scale simulation, which is installed jet fan with the actual distance. The middle of two shafts with relay station fires in the tunnel is assumed to be the most dangerous situation (worse case) as the main FDS simulation scenarios. Through tests, the study find out that the location of the first relay station is easier to produce back smoke layering among three relay stations. Furthermore, this study used original smoke control model: Eva1 to Eva4 with different Jet Fans and Axial-Flow Fan activation mechanism as 4 analysis scenarios as a comparison. Evacuation mode using the original emergency operation design could activates the four groups upstream Jet Fan, and activates downstream Jet Fan with intervals way. Through a series of tests, the study find out that in accordance with fire sources with 15MW and 30MW, the passers-by upstream 30m at the fire source to could evacuate successfully before achieving safety criteria threshold; however, the most serious fire with 65MW, road users could not evacuate efficiently. The study found out that original smoke control mode in tunnel could not exhaust smoke efficiently. In order to prevent the smoke layer disturbance, it is necessary to comply with the activation principles, the Jet Fan could not be activated between 250m upstream position and 500m downstream position. To improve the original no enough efficient smoke control model, this study adopted 5 kinds of optimization design scenarios to analyze smoke control efficiency further. The simulation result found out that in the downstream position of the fire source regardless of any smoke control model, all fire scenarios would endanger the refuge. In contrast to upstream safety under good safety management, we analyze adults and people with disabilities with walking speed of 1.2 m / s and 0.64m / s, separately, the result has shown that the total evacuation time required 205 seconds and 227 seconds, respectively. Furthermore, under evacuation mode with 15MW fire sources, all passengers could evacuate efficiently before safety criteria threshold time; however, the 30MW and 65MW fire source could not, which is the most serious fire accident type with 65MW in the tunnel. Therefore, in comparison with 6 fire scenarios, the result has shown that scenario 5 is the best evacuation design under three fire sources at the upstream position. The visibility of upstream and downstream position at fire sources affected road-users’ safety faster than temperature of those. Take scenario 5 as an example, while the 6 upstream groups and 4 downstream groups of jet fans activated under the same air flow rate each JF, compared scenario 5 (no back smoke layering effect) with evacuation mode (with back smoke layering effect), evacuation mode increased 224 to 259 seconds evacuation time, thus slowing the smoke layer fall time around 224 to 259 seconds. The visibility at the downstream position achieved the safety criteria threshold faster than fire parameters at those. Comparison the 6 upstream groups and 4 downstream groups of Jet Fans with the 4 upstream groups and 4 downstream groups of Jet Fans activation, the former could lower toward upstream evacuation time around 22 seconds (15MW), 24 seconds (30MW), 30 seconds (65MW) separately, because the Jet Fan activated to accelerate the decline visibility and rise temperature in the downstream position, but while activated the Axial-Flow Fan at the shaft, evacuation time could increase about 11 to 24 seconds.