| 摘要: | 本島山岳隧道工程目前主要面臨地質變動頻繁、斷層與剪裂帶密度高及地下水豐沛等不利因素，其中大量且高水壓之地下湧泉，易發生隧道嚴重抽坍，尤難處理，因此本研究以坪林隧道導坑工程於里程39K+074處遭遇湧水災害之處理案為例，說明湧水地盤的地質特性及處理原則，並作進一步的研究分析，期能對山岳隧道之湧水處理提供一規劃的思維方向。 本研究依據坪林隧道四稜砂岩地層發生大湧水夾帶泥屑流動之地質弱帶處理案例及坪林隧道3號豎井進氣井現地回復試驗，得到滲流係數及灌漿有效範圍等之相關經驗及資料，並針對裂隙岩體滲透性質及湧水處理結果作分析與討論，進而研擬爾後類似案例之鑽灌處理模式。 裂隙岩體的滲透係數，將隨覆蓋深度的增加而逐漸變小，且滲透係數，非常離散，難以藉由幾個試體即可求得準確的滲透係數。 土體灌漿量的擬定，就土體本身而言，應以孔隙率為主要衡量因子，而岩體灌漿量的擬定，則應以裂隙率為主要衡量因子。 依據坪林隧道導坑過去的鑽灌經驗，建立鑽灌處理流程及歸納出最適當之鑽灌時機及灌漿方式，並提出三種不同形式之灌漿孔佈置，俾能提供類似案例規劃鑽灌處理模式之思維方向。 在隧道開挖施工過程，若遭遇特殊地質情況，首先應依據岩體的特性、水文地質、工程需求、環保要求、施工機具設備、施工材料等因素，研擬地盤改良方案，俾能據以執行後再依實際狀逐步調整。 Complicated geological conditions, high frequency of faults and shear zones, and abundant groundwater are the main difficulties in tunneling in Taiwan. The treatment of cave in hazard due to the large quantity of groundwater ingression with high pressure is extremely difficult. Cases study in grouting treatment of geological weak zones with groundwater ingression in Pinglin Pilot Tunnel at Sta. 39K+074 are reported and evaluated in this thesis for providing a direction of planning for treatment of water influx in tunneling. Corresponding experiences for treatment, data which include permeability and effective range for grouting in this research are obtained from two cases, one is the treatment of weak geological area which contains abundant groundwater with debris flow in the Szeleng Sandstone formation of Pinglin Pilot Tunnel, another is the recovery method from No.3 Fresh Air Shaft at the Pinglin Tunnel, the model of grouting treatment for permeable ability of fissured rock is established for application in similar situations encountered later on. Permeability of fissured rock mass is decreasing when embedment depth is increasing, the permeability is quite dispersing and it is difficult to obtained an exact value from several test only. Porosity is the major factor for the planning of injection quantity when grouting in soil mass, but for the rock mass, which is mainly based on fracture aperture. According to the grouting experience in the Pinglin Pilot Tunnel, 3 types of grouting pattern are suggested based on following procedure, first the III treatment flow chart is established, the most suitable time and proper grouting method are concluded in accordance to in-situ situation, these are provided a direction of planning for grouting treatment on simulated cases. When special geological condition is encountered during the tunnel excavation, the planning of ground improvement method is based on the consideration of several factors, such as, rock mass characteristics, hydrological geology, engineering and environment, construction equipments and materials. The ground improvement is carrying out due to the planning method and it is alternated according to the in-situ situation. |
