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| APPLICATIONS OF GEOSYNTHETICS ON GEOENVIRONMENTAL ENGINEERING |
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| 劉家男 |
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| 環境地工、廢棄物掩埋場、地工合成材料、應用、設計、施工 |
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| 由於地工合成材料能符合諸如排水、阻水、加勁、隔離、過濾等功能，因此地工合成材料在環境地工上之應用日漸普及。本文首先將以廢棄物掩埋場為例說明環境地工中常需要考慮之問題介紹，並且介紹地工合成材料之基本性能，以及如何針對不同環境地工問題之需求來選用適當之地工合成材料以及應用情形，本文最後將介紹於環境大地工程問題中使用地工合成材料時必須考慮的設計、選材、試驗、施工等重點。 |
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| Because the geosynthetics can serve the purposes of drainage, barrier, reinforcement, separation and filtration, it is widely applied on the geoenvironmental related engineering. Through introducing the landfill structures, this paper presents the common features of geoenvironmental engineering. The capabilities of some geosynthetic products are also briefly introduced. The applications and selection of suitable geosynthetic products to special engineering requirements are presented. Finally, some important concerns about the design, material, testing, and construction on the application of geosynthetics on geoenvironmental engineering are introduced. |
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| SLOPE FAILURE OF MUNICIPAL SOLID WASTE LANDFILL |
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| 姚大鈞、蔡淵堯、李維峰 |
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| 一般廢棄物掩埋場，邊坡破壞，廢棄物強度 |
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| 由於一般廢棄物掩埋場(municipal solid waste landfill)中廢棄物之多樣性及其工程性質及強度隨時間而變化之特性，掩埋場之長期變形（沉陷）及穩定性分析與預測為工程上之一項挑戰。其長期穩定性受廢棄物強度隨時間而降低之影響，異於一般土石填方構造物隨時間而漸趨穩定。若因超量填埋、封場後管理不善或設計施工不良，易造成長期安全上之危害。本文以某一廢棄物掩埋場之破壞為例，闡述因封場後管理不善及超量填埋引致之安全問題。 |
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| The refuse received by MSW landfill consists of material in various physical and chemical properties and different shapes. The engineering properties of refuse change with time and make it a challenging endeavor to correctly predict and analyze the long-term deformation as well as stability of sanitary landfill. The strength of refuse usually decreases with time and affects stability of landfill whereas most of the engineered fills become stable with time. The long term stability of sanitary landfills is usually jeopardized by excessive fills of refuse, inadequate design, or lack of proper management after closure. A slope failure case of an old MSW landfill is introduced with respect to the long-term stability of sanitary of landfill. |
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| THE SETTLEMENT BEHAVIOR OF LANDFILLS AND ESTIMATION |
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| 劉家男、陳榮河、 陳國賢 |
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| 掩埋場、垃圾、沉陷、預估模式 |
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| 對於垃圾掩埋場之封閉、沼氣收集、與滲出水收集等系統之設計，及封閉後場址復育與利用之規劃、設計與分析，沉陷量皆是一個重要的考慮因素，然因垃圾具組成複雜及生物分解之特性，加上掩埋操作因素及環境因素等之影響，使掩埋場沉陷行為益加複雜，故目前對掩埋場之沉陷行為仍未能充分了解，而沉陷之預估方法亦莫衷一是。本研究藉由所收集之掩埋場沉陷紀錄與垃圾材料壓縮試驗等資料，透過相關力學參數之整理與分析，來探討掩埋場沉陷行為之特性及其與影響因素之關係。此外，介紹三種目前常用之沉陷預估模式，說明並比較各模式之優缺點。最後，以兩個垃圾掩埋場沉陷所引致相關工程問題之案例，說明封閉後垃圾掩埋場址之復育或作為其他用途時，沉陷量之預估是一極為重要且不可輕忽之議題。 |
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| The amount of settlement is an important factor regarding the design on landfill cap system, biogas recovery system, leachate collection system, and rehabilitation of enclosed landfills. However, the settlement behavior of landfill is not fully understood nowadays because the waste material is heterogeneous and biodegradable, as well as the local effects of surrounding environment and landfilling operation. Besides, in practice, there is no appropriate model to predict the settlement of landfill. In this study, both data of published landfill settlement and compression tests of waste material are collected and analyzed for the quantitative study of the characteristics on the landfill settlement behavior and its effect factors. Besides, three prediction models are introduced and discussed. Finally, two cases about the engineering problem that is induced by the settlement of closed landfill were discussed to illustrate the importance and essentiality to estimate the settlement of landfill. |
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| EVALUATION OF GAS MIGRATION POTENTIAL THROUGH LANDFILL COVER SYSTEMS |
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| 單信瑜、姚振天 |
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| 掩埋場、覆蓋系統、導水度、透氣係數 |
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| 掩埋場底部阻水系統和上部覆蓋系統常用的不透水材料包括夯實黏土、地工皂土毯、以及地工止水膜等。過去的研究多著重於阻水能力相關議題，但近來這些材料應用在覆蓋系統時的行為逐漸受到重視。土壤材料經過乾濕循環、冰凍解凍、甚至是差異沈陷後，所產生的裂縫將引起透氣性的大幅上升，過量的甲烷氣排放會造成對環境的影響。本研究將焦點放在覆蓋層中之阻水層，並探討其乾縮行為對覆蓋層透氣性行為之影響。實驗結果發現，不論是夯實黏土或是地工皂土毯，在乾燥環境之下，皆無法抵抗乾縮變形而產生裂縫，且50cm的覆土亦不足以保護其下的材料，因此建議在乾燥地區掩埋場覆蓋層中阻水層的設計應加上地工止水膜，當作阻隔氣體的材料，以避免掩埋場中所產生的氣體，溢散至大氣之中，造成對環境的危害。本研究利用土壤保水試驗和氣體滲流試驗研究覆蓋系統土壤阻水材料的透氣行為，結果發現，無論是夯實黏土或地工皂土毯其透氣性都隨著含水比增加而降低，雖因為地工皂土毯的保水能力較佳但在不飽和狀態下其裂縫較大，所以其透氣性會較夯實黏土高。無論是夯實黏土或地工皂土毯，若能夠維持高飽和度，則透氣性可以維持極低；反之，無法適當的保護土壤 |
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| The hydraulic barrier material most often used in landfills are compacted clay, geosynthetic clay liner, and geomembrane. In the past, most of the researches have focused on the ability of these barrier materials to retard the migration of water. However, compacted clays and geosynthetic clay liners tend to crack due to wet/dry cycles. In this research, the effect of desiccation on the air permeability of hydraulic barrier in cover system was studied. The results show that both compacted clays and geosynthetic clay liners may crack when they are subjected to a hot and arid environment. Furthermore, a soil cover of 0.5 m may not be thick enough to prevent the development of the cracks. It is therefore suggested that the barrier layers in cover system of landfills in arid or semi-arid area should include geomembrane to prevent the emission of landfill gas. |
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| INTRODUCTION TO THE CHARACTERIZATION, INVESTIGATION AND REMEDIATION OF SOIL AND GROUNDWATER CONTAMINATED SITES |
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| 斯克誠 |
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| 土壤、地下水、污染場址、調查、整治 |
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| 國內之土壤及地下水污染事件於近年不斷頻傳，對於污染場址周遭之土地利用及居民健康造成相當大影響，故環保署已於民國八十九年公布「土壤及地下水污染整治法」，以推動污染場址之調查及整治工作。本文針對污染場址之污染原因、污染特性、污染調查方式、整治工作、場址整治案例等進行綱要式之說明，期使其他工程領域人士對此有初步之瞭解，以共同推廣污染場址之調查與整治工作。 |
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| Many soil and groundwater contaminated sites have been reported in Taiwan in recent years. Consequently, the land value and the local residential health near the sites are seriously threatened. Taiwan EPA promulgated the Soil and Groundwater Remediation Act in 2000 to take actions on these contaminated sites. This article briefly describes the pollution sources, the characteristics of contamination, investigation methods, remediation work, and case studies so that the engineers in other professional areas can understand this new engineering field. |
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| THE EFFECT OF PILING ON THE AQUITARD LEAKAGE |
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| 吳淵洵、呂漢鎮 |
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| 地下水污染、打擊樁、阻水層、滲透性 |
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| 本研究針對打擊樁可能造成低滲透性阻水層之滲漏現象(aquitard leakage)以試驗觀察方式進行探討。研究結果顯示砂土層中夾薄層黏土可使土層之豎向滲透係數(k)由 10-3降低至 10-6 cm/sec，顯示黏土確可控制k值之變化。但當基樁貫穿黏土層後，不論滲透液體為水、汽油或二氯乙烷，k值均呈現明顯之增加，其值隨黏土層厚度(t)與樁徑(D)比值(t/D)之降低及基樁貫穿黏土層長度(Lo)與黏土層厚度比值(Lo/t)之增加而遽增(由10-6~10-8上升至l0-3~10-4cm/sec)。顯示基樁貫穿黏土層之過程中，樁尖之推擠與樁壁之拽引作用，可迫使砂土進入黏土層中，破壞其均質性，形成主要滲流路徑，而造成k值之增加，惟此種影響有其極限，當t/D³1.7或Lo/t £1.0時，打樁對黏土層之阻水功能即無明顯影響。綜合而言，本研究藉由試驗證實基樁對薄層黏土層之污染拘限功能具有嚴重影響，可供工程界於類似狀況之地下水污染預防、調查與整治工作之參考。 |
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| This research was conducted using laboratory experiments to observe the piling effect on the aqitard leakage. Test results showed that clayey lenses present in a sandy stratum tend to drop the vertical permeability from 10-3cm/sec to 10-6cm/sec. The vertical permeability appears to be governed by the interbedded clayey lenses even their thickness are negligible. However, when pile was penetrated through the clay and no matter what the permeants were used (water, gasoline, or dichlorethane); the vertical permeability (k) values all increased by orders of 3 to 4 magnitudes. Parameters that affect the k values are clay thickness (t), pile diameter (D), and pile penetration length beyond the clay (Lo). The k values increased with decreasing t/D or increasing Lo/t. The pile penetration appears to push and drag appreciate amount of upper sand into the clay layer, develop a preferred flow pathway, and thus cause the permeability to increase. However, such effect was diminished when t/D>1.7 or Lo/t <1.0 and k almost decreased to its initial value. The observations found in this research indicate that piles driven through the aquitard may lead to significant leakage. Such findings will be helpful for prevention, investigation, and mitigation of groundwater contamination in similar conditions. |
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| THE APPLICATION OF COMBUSTION BOTTOM ASH IN GEOTECHNICAL CONSTRUCTION |
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| 李維峰、陳育聖、陳雨音、胡志誠、姚大鈞 |
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| 垃圾焚化底渣、道路基底層、控制性低強度回填材料、再生資源 |
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垃圾焚化底渣係指垃圾焚化廠以焚燒方式處理都市固體廢棄物（Municipal Solid Waste, MSW）後所殘餘之灰渣，又稱焚化底渣。底渣具有比重輕、吸水率高、具有多種重金屬（如如銅、鉛、鉻、鎘、鋅等）、高鹼性、高氯離子含量等特性。
有鑑於國外對於底渣資源再利用之技術已成熟且已有諸多地工方面之實務應用，本文主要彙整國內近年來對於底渣再利用之相關研究成果，包括底渣取代天然材料應用於道路基底層與路堤回填料以及CLSM等應用。希望藉由本文之介紹，能有效利用底渣此種再生資源，進而減少天然資料之消耗，達到資源永續經營的目的。
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| Combustion bottom ash is a residue produced by the mean of incinerating municipal solid waste at trash incineration. The municipal waste bottom ash has several characteristics, such as light specific gravity, high absorptivity, heavy metal, including copper, lead, chromium, and zinc, etc., high basicity, and high concentration of chloride, and so on. In consideration of sophisticated technology of bottom ash recycling and practical applications of geotechnical engineering in Taiwan, recent studies of bottom ash recycling are collected in this paper including that bottom ash replaces for natural materials in base layer of road and application of CLSM. Hopefully, due to this introduction of bottom ash recycling, a decrease in loss of natural materials and perpetual operation of natural resources could be achieved. |
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| GROUND IMPROVEMENT WITH SUPERJET-MIDI METHOD |
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| 方永壽、簡國峰、王大榮、高宗正、周黎明 |
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| 噴射灌漿、測音作業、滲透係數、SJM工法、改良土、單軸壓縮強度 |
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| 本論文介紹Superjet-Midi超高壓噴射灌漿工法（簡稱SJM工法）之特性、施工方法、及改良土工程性質。與常用之JSG噴射灌漿工法相比較，SJM工法使用直徑較粗的二重灌漿管(90.0 mm＞60.5 mm)、較高之噴漿壓力(300kgf/cm2＞200 kgf/cm2)、較大的噴嘴直徑(5.0 mm＞2.0 mm)，及較大的漿液吐出量(400 l/min＞60 l/min)，因此在地下形成大直徑(2.4~3.5 m)的改良土樁體。台北捷運土城線隧道工程，首度自日本引進SJM噴射灌漿工法進行地盤改良作業，並首次採用測音作業以確認改良土之樁徑。此標工程SJM改良土取樣率介於90﹪至99﹪之間，明顯高於施工單位設定之檢驗標準80﹪。SJM改良土之岩心品質指標RQD介於79﹪至97﹪間，其平均值高達88﹪，顯示改良土品質良好。砂質土SJM改良土的單軸抗壓強度qu介於3.65至22.6MPa之間，黏性土改良土之qu介於1.88至10.0 MPa之間，皆符合設計之要求。本案例SJM改良土的彈性模數E50介於350至1,990MPa之間，符合日本Superjet研究會要求的砂質土改良土E50≧300 MPa，及黏性土改良土E50≧100MPa。SJM改良土的強度qu與勁度Et50之關係，大致可以日本JSG協會建議之E50＝100qu~300qu加以描述。現場變水頭透水試驗求出SJM改良土之滲透係數介於3.2至6.6×10-7 cm/sec之間，皆低於設計值10-5 cm/sec，可知改良土止水效果良好。 |
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| This paper presents ground improvement with Superjet-Midi (SJM) method. The procedure of construction and engineering properties of the soilcrete are introduced. The SJM method was first adopted in Taiwan for the construction of Taipei Rapid Transits Systems. The jet-noise monitoring technique was first used to identify the diameter of soilcrete column formed in the ground. Cylindrical specimens were drilled from the site and tested in the laboratory. It is found that the core recovery of the samples varies from 90% to 99%, which is higher than the design requirement of 80%. RQD of the specimen varies from 79% to 97%. The uniaxial compressive strength qu of the sandy soilcrete varies from 3.65 to 22.6 MPa, which is greater than the design requirement of 3.0 MPa. The qu for clayey soilcrete varies from 1.88 to 10.0 MPa, which is higher than the design requirement of 1.0 MPa. The relationship between the strength qu and stiffness E50 of the soilcrete can be described with the formula E50 = 100qu ~ 300qu proposed by the JSG Association (1986). The permeability of soilcrete changes from 3.2 to 6.6 × 10-7 cm/sec, which is significantly lower than the design requirement of 10-5 cm/sec. |
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