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| IN-SITU STRESS MEASUREMENT USING HYDRAULIC FRACTURING AND THE USE OF FAILURE CRITERIA |
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| 楊明宗、歐陽湘、柳志錫、吳建宏 |
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| 水力破裂法、現地應力、Hoek-Brown破壞準則 |
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| 水力破裂法為一廣為人知的現地應力量測方法，不過在國內仍然少有現地施測的相關經驗與資料，本文藉由在國內進行的一項現地試驗來說明水力破裂法的施測流程與分析方法，而本次試驗結果於238m至430m區間內，其最大水平應力為8.41～14.43MPa，最小水平應力為4.54～9.38MPa，整體而言主應力在西北－東南方向。此外，本文嘗試引進Hoek-Brown破壞準則，探討現地應力的修正方法，以能解析水力破裂法於產生水平裂縫時之現地應力大小。 |
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| Hydraulic fracturing is a well-known method to measure the in-situ stress, but the local testing experiences and data are limited in Taiwan. In this paper, an accomplished domestic in-situ test is taken as an example to illustrate the testing process and the analysis method. The testing results show that the local maximum and minimum horizontal stress are 8.41~14.43 MPa and 4.54~9.38 MPa at depths from 238m to 430m, respectively. And the principle stress direction is NW-SE. In addition, the Hoek-Brown failure criteria is adopted to estimate the in-situ stresses when the fracturing cracks would occur horizontally during a test. |
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| EXTENSION OF RMR AND Q-SYSTEM IN TAIWAN |
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| 張吉佐、侯秉承、李民政、李怡德、張博翔 |
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| 岩體分類、隧道工程 |
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山岳隧道之力學機制相當複雜，隧道支撐設計常以經驗設計法為主，力學分析法為輔。而岩體分類法提供一個簡單快速之評估方法，可將眾多影響隧道穩定性因子納入考量，進而輔助隧道支撐設計，為隧道工程中不可或缺之工具。台灣地區自從1970年代開始大量採用新奧工法以來，多援用南非RMR系統與挪威Q系統進行岩體分類，在累積了幾十年的經驗後，有必要對前述岩體分類的適用性加以重新檢討，並建立適用於本地區的岩體分類系統。
本文先就現行岩體分類系統使用情形加以探討，包括岩盤隧道工程與固結不良地盤隧道工程之應用現況，進而依據地質材料特性，參考地質年代、對水的敏感性以及相關強度特性，將台灣全區之地層劃分為 A、B、C、D 四種岩類（rock type），並據此建立各岩盤類別之岩體分級標準（rock mass classification），作為台灣地區制定隧道支撐系統之依據。
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The mechanism of mountainous tunnels is quite complicated. At present, empirical methods are basically used in tunnelling design and analytical or numerical methods are adopted as a supplementation. While using empirical methods, rock mass classification is a vital tool because it embraces many factors that affect the stability of a tunnel. It also provides a simple and useful design means of tunnel supports. Since 1970’s, New Austrian Tunnelling Method (NATM) has been widely used in Taiwan. Moreover, Q-system of Barton et al. and RMR-system of Bieniawski are commonly used to classify the rock mass. However, local geologic characteristics have never been taken into considerations in these systems. It is necessary to review the suitability of these systems and extend them on the basis of the domestic experience accumulated in last several decades.
This paper begins at discussing the applicability of existent rock mass classifications in Taiwan, including the applicability in rock tunnels and unconsolidated weak ground tunnels. Moreover, this paper develops a new classification system, which classifies rock formations in Taiwan into four types: A, B, C and D. The above system is on the basis of local geologic material properties, geologic age, sensitivity to water and relevant strength characteristics. It also formulates the criteria, which are regarded as the bases of designing tunnel-support systems, for rating various rock types in Taiwan
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| THE DISPLAY AND APPLICATION OF THE 3-D DEFORMATION DATA OF TUNNELS |
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| 彭嚴儒、陳堯中 |
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| 隧道三維變形、趨勢線、地質變化 |
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| 傳統的隧道監測工作僅能測得兩觀測點之相對變位，對於開挖所導致複雜的三向度變形行為，所能提供的預警訊息相當有限，特別在異質性高的地質條件下更為明顯。對此奧地利學者發展一套完整的隧道三維變形回饋分析機制，藉由測點之絕對變位量測，不但能反映開挖面附近之變形行為，亦能根據不同的行為特徵來預判開挖面前方可能的地質情況，因此本文將就國外發展之隧道三維變形量測資料展示方式及其應用原則做一介紹，期望能對提升國內隧道工程之施工安全及品質有所助益。 |
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| Traditional tunnel monitoring practice measures the relative displacements between two measuring points. For complex three-dimensional tunnel excavation behavior, it provides limited information about the safety of tunnels, especially under the conditions of highly heterogeneous geology. To meet the demands of tunnel safety, a new scheme of data presentation is developed by Austrian scholars. It could reflect the deformation behavior around the excavation face according to the characteristics of different deformation curves. This paper introduces the methods of presenting the 3-D deformation data and their applications. It is hoped that the safety and quality of tunneling could be improved by applying better monitoring technique in our country. |
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| MECHANICAL BEHAVIOR OF A TWIN- TUNNEL IN MULTI-LAYER FORMATIONS |
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| 褚炳麟、張義隆、林永祥、徐松圻 |
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| 雙孔隧道、多層介質岩層、虛擬應力法 |
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| 本文採用邊界元素法中之虛擬應力法(FSM)，並考慮不同介質界面上應力與位移之連續條件，再佐以Hoek & Brown 之岩石破壞準則，建立一套二維數值分析模式，以模擬界面為水平之多層介質雙孔隧道開挖之力學行為。本文並依據各層岩盤之彈性模數比、初始應力大小及側向壓力係數Ko等參數，分別探討多層介質岩盤中，未支撐圓形隧道圍岩之過應力區及應力與變位之影響行為。經由與隧道物理模型試驗結果比較發現，數值解與實驗值相差僅約2~4%，顯示FSM多層介質模式可適切模擬多層岩盤中隧道開挖之力學行為。此外，本文亦發現過應力區會往最小主應力之方向延伸，而變位則會往最大主應力之方向發展。顯示當最大主應力方向平行於隧道排列方向時，隧道之穩定性較佳。 |
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| By considering the continuity equation for stress and displacement at the interface, a 2-D numerical simulation based on the Fictitious Stress Method (FSM) is developed to study the mechanical behavior of a twin-tunnel with circular cross section in multi-layer formations. The distributions of displacement around the unsupported tunnels are analyzed. In addition, the over-stressed zone around tunnels is determined based on Hoek and Brown’s failure criterion under various configurations. Here, the variables considered are the modulus ratio, initial stress, and coefficient of earth pressure (Ko). The numerical results are found in a good agreement with the experimental results within an error of 2-4%, indicating the FSM model could be regarded as a suitable mean to solve the mechanical behavior of tunnel excavation in multi-layer formations. The result also shows that the over-stressed zone is found to extend along the minor principal stress direction, whereas the displacement is found to extend along the major principal stress direction. |
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| TUNNELING IN LOOSELY CEMENTED SAND LAYER / STIFF CLAY -- LANTAN TUNNEL |
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| 張吉佐、劉弘祥 |
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| 砂泥層地盤、側導坑工法、鋼纖維噴凝土、桁型鋼支保、管冪鋼管 |
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| 蘭潭隧道為典型砂泥層地盤之隧道工程，其位於嘉義市仁義潭與蘭潭間之雙孔各三車道隧道，各孔之長、寬、高分別約1.2km、17m及12.6m，開挖面積約172m2，兩孔中心間距約40m。全線地質狀況可歸類為軟弱泥岩、膠結疏鬆砂層及砂泥岩互層，覆蓋深度約35~80m，地下水位線高於隧道頂拱約10~20m。本隧道開挖範圍大，地質情況甚差且地表有姜母寮村民房。為防止開挖塌陷等問題，除了開挖前於地表以抽水井方式降低砂層地下水位之外，開挖時於開挖面鑽設排水孔進一步排水；開挖時除泥岩採用三台階開挖工法外，均採用雙(單)側導坑開挖工法，另於頂拱及側壁以管冪鋼管或先撐鋼棒作為先撐措施。支撐材料包括鋼纖維噴凝土、岩栓及桁型鋼支保等。隧道全線以鋼筋混凝土襯砌，路面採用混凝土剛性路面設計，均符合安全、舒適之行車要求。 |
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| The essential factor to successfully conduct tunneling in loosely cemented sand layer / stiff clay is to sustain the inherent strength of the surrounding rock after excavation. To achieve this goal, an effective support system must be installed timely so as to confine the convergence of the tunnel as much as possible. A successful case history of tunneling in weak ground is presented in this paper. The Lan Tan Motorway Tunnels, with twin tubes and each with three lanes, each tube is about 1.2km long, 17m wide and 12.6m high and excavation area of 172m2. To maintain face stability during tunnel excavation and minimum difficulties during tunneling, the ground water is predrained from a series of wells before excavation and meantime additional horizontal drainage pipes are installed from excavation face during tunneling. The weak ground conditions are excavated using one or two sides gallery method. To stabilize excavation face, further supporting system of using steel pipe roofing or steel bar forepiling is preinstalled over the crown and side walls of the tunnel. The primary supports are mainly used steel fiber reinforced shotcrete, rock bolts and lattice girders. |
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| TBM TUNNELING IN NEW WUCHIEH AND LISHI CREEK DIVERSION TUNNEL PROJECT |
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| 李明雄、李鴻洲、李慶龍、鄭建和、黃偉光、劉欽正 |
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| 引水隧道，隧道鑽掘機（TBM），長距離地質鑽探，鑽掘效率，擠壓性岩盤，施工工率 |
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| 台灣電力公司『新武界隧道及栗栖溪引水工程』之隧道總長約16.5公里，其中中游段之引水隧道長約7.8公里，因推估地質均質尚佳且無明顯之剪裂帶或斷層帶存在，並為考慮縮短工期、降低對環境之衝擊、減少勞工需求及提昇台灣隧道工程施工技術等因素，決定採用安全且連續一貫快速作業之隧道鑽掘機（TBM）開挖施工。施工期間，於西元2001年11月份創下659.3m/月之台灣最快鑽掘紀錄，其後雖曾遭遇局部岩盤破碎或異常擠壓等不良地質，以及遭受桃芝颱風之暴雨肆虐成災，然於採取適當應變措施及處理得宜下，TBM終於克服困難並持續順利鑽掘，且於2002年6月7日TBM段隧道順利貫通，完成鑽掘工作，為台灣隧道工程首次以TBM貫通案例，且達到最佳平均月進度（315m/月）及最大鑽掘長度（6,523公尺）之新里程碑。本文簡要說明施工前地質探查、TBM設備與支撐設計、TBM施工，以及鑽掘效率檢討、不良地質處理等，期能提供爾後隧道工程TBM開挖施工參考。 |
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| The total tunnels length of the New Wuchieh Diversion Tunnel & Lishi Creek Diversion Project, Taiwan Power Company, is about 16.5 km. Considering the homogeneous rock condition and without obvious disadvantageous geological structures, the middle section 7.8 km long tunnel is excavated by the TBM (Tunnel Boring Machine). TBM tunneling can not only shorten the construction period but also lower the impact of the environments, requiring less labor and improving the tunneling technique of Taiwan. During the working period, a serious earthquake, squeezing grounds and a heavy typhoon had been encountered. With proper measurements and treatments, the excavation of the TBM is very smooth. On June 7th 2002, the tunnel is the first successful break-through of TBM tunneling in Taiwan. The best monthly progress of 659.3m is achieved on November 2000, the best daily progress is achieved on January 3rd 2001. The average monthly progress of 315 m and the length of 6523m became a new milestone of Taiwan. This report briefly introduces the project from planning, design and construction point of view, can be referred for future TBM tunneling. |
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| REVIEW SOLVE MEASURES ABOUT THE NEW YUNG-CHUNG TUNNEL HIGH PRESSURE WATER INGRESS PROBLEM |
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| 傅子仁、薛文城 |
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| 隧道、高壓湧水、水平長距離鑽探、熱瀝青灌漿 |
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| 新永春隧道於87年10月發生國內外隧道工程罕見之持續巨量高壓湧水災害，檢討處理過程中，在專案處理工程團隊通力合作，掌握處理流程隨時修正後續之因應措施，始決定下階段因應方案，充分發揮決策彈性處理機制，並引進熱瀝青灌漿工法等技術克服困難，是為處理成功圓滿之主要因素。更以謙卑以對的態度，學習瞭解大地，在互信與共同努力下，終能圓滿達成任務。 |
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| In October 1998, during the excavation of New Yung-Chung Tunnel, massive and high-pressured water ingress occurred at the south portal workface. The project has been successfully completed and the measures as implemented for this long-lasting water ingress problem are reviewed and discussed herein. During the remedy work, the task force modified the procedures or methodologies based upon the newly obtained supplemental geologic data and the results of the previous treatment steps. The conducted hot bitumen grouting program, first time in Taiwan, has reduced the hydraulic conductivity of the surrounding formation which is the key point to make the tunnel excavation through the water bearing zone. The team members with humble attitude modified the design corresponding to the changes of the ground conditions and, under mutual trust and well cooperation, completed the most difficult mission at last. |
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| THE STABILITY ANALYSIS OF ROCK SLOPES BY A FRACTURE MECHANICS APPROACH |
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| 王建力、葉時青、陳志豪 |
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| 岩石、邊坡穩定分析、斷裂力學 |
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| 本文介紹以斷裂力學分析方法探討岩石邊坡受應力集中效應對岩石邊坡破壞行為方面可提供的解釋機制。本研究利用有限元素程式ANSYS進行岩石邊坡穩定分析，以分析在動力作用下含裂紋岩石邊坡之反應行為。為評估斷裂力學分析方法，本文選取草嶺附近之一邊坡案例分析並比較邊坡穩定分析程式STABL5與ANSYS分析之結果。 |
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| A fracture mechanics approach has been proposed in this study to predict rock slope stability mainly caused by stress concentration. A finite element program, ANSYS, has been adopted in this study. The transient analysis module of ANSYS makes it possible to predict the deformation of a rock slope under the dynamic excitations. Sensitivity studies have been carried out. A major rock slope near the Tsao-Ling area as a case study was accordingly investigated. The result using a limit equilibrium program, STABL5, has been compared with the fracture mechanics approach. |
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| AN INTRODUCTION TO SLOPE FAILURE MODE AND PREVENTION IN SLATE AREA OF CENTRAL CROSS-ISLAND EXPRESSWAY |
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| 李彪、劉志學 |
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| 中橫快速道路、板岩、邊坡穩定 |
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| 中橫快速道路埔里花蓮段之前段位於板岩區內，有較多之邊坡穩定問題必須加以評估，而邊坡穩定性評估因素，主要包括岩性、岩質、侵蝕作用、斷裂構造及地形等。分析評估建議需包含材料破壞及構造破壞兩種模式。由於地質條件的多變性、不確定性，設計者往往不易掌握適當之地質參數與條件，因此應於規劃階段設計一套完整之作業計畫，有系統的獲取各項評估參數，以及建立適當之邊坡地質模式，以供邊坡穩定分析評估以及設計之用。邊坡破壞的防制在各環節上是緊緊相扣的，而最佳化的第一步仍在於釐清地質條件及可能之破壞模式，如此才能提供適當的參數與地質模型予設計者，進而完成適當的防制措施。 |
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| In the Central Cross-Island Expressway between Pule-Hua-lian section, the front part is located on the slate area. So there are many slope stability issues, that need to be evaluated before construction. For stability evaluation, Key factors are lithology, rock mass specialty, erosion, crack structure, topography, and etc. We suggest the stability analysis should include the mechanism of material and structural failure. Due to variable and uncertain geological conditions, the designers are often troubled with selecting appropriate geological parameters. For this reason, we should integrate whole operation plan in planning phase. Then we can obtain each design parameter systematically, and build a suitable model of the border-sloping field. The results can be used to evaluate and design the stability of the border-sloping field. To prevent the slope failure, every steps are tightly linked to influence each other. The first step of optimization is to understand the geologinal condition and the probable failure mechanism. So we can provide suitable parameters and geological model to the designer, and help them accomplish appropriate precautionary measures. |
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| DRILLED SHAFTS BEARING CAPACITY IN SOFT ROCK |
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| 古志生、李德河 |
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| 軟岩，鑽掘樁，樁載重試驗 |
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| 我國西部麓山帶有許多上新世與更新世所沉積而成之地層，其岩性以膠結不良砂岩、粉砂岩及泥岩(頁岩)為主。這些岩層之成岩時間較短，岩質膠結不良而岩性軟弱，具有遇水軟化或崩解之特性。重大工程常使用之大口徑樁基礎在此種介於岩石與土壤之特殊地質材料的承載力是相當有趣的研究課題。本文藉由軟岩地層鑽掘樁的樁載重試驗，採用不同的詮釋法評估其軸向極限承載力，並進行軟岩基樁承載行為之探討。分析結果發現樁身阻抗樁所佔之荷重比例隨樁頭變位之變動而遞減，至最大試驗荷重21.22MN時之樁身阻抗約為40%；而且在軟岩層之單位平均樁身阻抗與對應之樁頭變位有關，約介於120kPa至196kPa之間。 |
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| In the western foothills of Taiwan, most soft rock strata are sedimentary rocks formed in Pliocene and Pleistocene. As the soft rock was a young formation, the cementation of the rock is quite weak and susceptible to weathering, slaking and erosion. In recent years, many public construction projects took place in the soft rock-rich western Taiwan. The side resistance and end bearing of shaft in soft rock is one of the interesting research subjects. Pile tests results were collected to investigate the drilled shaft bearing capacity in soft rock. The results show that the ratio of friction and test load is the function of pile head settlement, and is about 40% at the maximum test load. Meanwhile, the unit side resistance of pile in soft rock is the function of pile head settlement. The unit side resistance ranges from 120kPa to 196kPa. |
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