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| THEORIES OF EARTH PRESSURE IN LIMIT EQUILIBRIUM |
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| 陳榮河 |
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| 土壓力、擋土牆、破壞面、極限平衡 |
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| 本文介紹四種極限平衡狀態之土壓力理論，即Rankine、Boussinesq、Coulomb、及Prandtl，除了將各理論之假設及適用範圍加以闡述外，並將各理論所推導得之土壓力分佈、土壓力方向、破壞面之幾何形狀等加以說明；所考慮之參數包括：土壤單位重、超載、土壤之剪力強度參數、及牆背之摩擦角等。另外，並比較各法之差異，同時也對土壓力之延伸應用加以說明，以了解土壓力理論應用之廣泛性。 |
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| This paper introduces four earth pressure theories in limit equilibrium, I.e., Rankine, Boussinesq, Coulomb, and Prandtl. The assumptions of the theories and their application are described. Besides, from each theory, the developed earth pressure distribution and earth pressure direction, as well as failure surface are introduced. The parameters considered in the theories include the unit weight of soil, surcharge, the shear strength of soil, the friction angle of wall, etc. The differences between these theories are compared. These earth theories can also be extended to other applications, such as the bearing capacity of shallow foundations. Hence, the application of the theories is wide. |
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| SEISMIC DESIGN OF MECHANICALLY STABILIZED EARTH WALLS AND RECENT DEVELOPMENT |
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| 李維峰、黃亦敏 |
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| 加勁擋土牆、擬靜態分析、擋土牆動態設計 |
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| 雖然目前有許多證據顯示加勁擋土牆在地震作用下比傳統擋土結構具備更佳之抗震能力，但在國內由於受限於相關設計及施工規範尚未制定完成，工程界對使用加勁擋土牆仍然缺乏信心。本文第一部份參考美國FHWA與NCMA的相關設計規範介紹加勁擋土牆動態設計分析的原理、考量及細節，主旨在說明其實加勁擋土牆的設計十分簡易，且不脫傳統土壤力學的範疇，第二部份則在介紹加勁擋土牆動態反應的研發現況及瓶頸，並提出國內未來從事相關研發工作的方向與重點。希望藉由本文使國內工程界對加勁擋土牆應用與設計能有更進一步的認識。 |
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| Although many field evidences have shown that mechanically stabilized earth walls (MSEW) possess etter seismic resistance than conventional retaining structures, some geotechnical engineers in Taiwan are not comfortable in using and designing MSEW system. Main reason for such situation is that official design and construction specification or guidelines have not been well developed yet. The first part of this paper presents theory, considerations, and details of the seismic design of MSEW based on the manuals published by FHWA and NCMA. The authors try to illustrate that seismic design of MSEW is based on nothing but basic soil mechanics. In the second part of this paper, the authors also summarize the recent research progress of seismic response analysis of MSEW system. Discussions and suggestions of future research are also described. The purpose of this paper is to upgrade the design and to promote the application levels of MSEW in Taiwan |
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| PRACTICE OF MSE WALLS CONSTRUCTION USING GEOSYNTHETICS REINFORCEMENT |
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| 賴世屏、劉家男、郭勝雄 |
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| 地工合成材料、加勁擋土牆、面版、加勁材料、填築土料 |
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| 施工是設計理想的展現，如果沒有正確的施工，即使是再高水準的設計，也只是紙上談兵罷了。但是要如何施工？依據什麼標準？此時一套良好的施工規範就相當重要。因此一項成功的工程施作，包括加勁擋土牆在內，將會要求一套完善且製作良好的材料及施工規範，以供作為營造廠商與工地監造人員之間，關於施工指導及工程要求的溝通依據。低劣的規範通常會導致營造廠商與業主代表的爭議。最常發現的問題是，同樣的加勁擋土牆系統卻採用不一樣或不適合的規範。本文並非提出一套完整的加勁擋土牆材料與施工規範，供讀者立即沿用。而是僅就地工合成材料加勁擋土牆備製其材料與施工規範時，所必需注意的事項一一說明。 |
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| A successful MSE Walls project will require sound, well-prepared material and construction specifications to communicate project requirements as well as construction guidance to both the contractor and inspection personnel. Poorly prepared specifications often result in disputes between the contractor and owner representatives. A frequently occurring problem with MSE systems is the application of different or unequal construction specifications for similar MSE system. Users are encouraged to utilize a single unified specification that applies to all systems, regardless of the contracting method used. The construction and material requirements for MSE systems are sufficiently well developed and understood to allow for unified material specifications and common construction methods. Guide construction and material specifications are presented in this paper for the most common types of construction |
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| DESIGN AND CONSTRUCTION OF REINFORCED RETAINING WALLS FOR TAIPEI – ILAN EXPRESSWAY |
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| 方明朗 |
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| 北宜高速公路、加勁擋土牆 |
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北宜高速公路路工段行經風景優美之深山及溪谷，路堤段因地形及考量原有之山區公路景觀而大量採用造形美觀之加勁擋土牆。
本文主要在說明北宜高速公路採用加勁擋土牆之考量背景、設計理念、穩定分析方法、材料規範、工程內容及施工情形，供工程界同業參考。 |
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Road works of Taipei-Ilan Expressway, cut through precipitous mountains and deep stream valleys, employed large amount of aesthetic reinforced retaining walls due to considering topography and natural beauty of the landscape.
In this paper, brief descriptions of employment background, design philosophy, methods of stability analysis, terial specification, content of works, and the construction of the reinforced retaining walls are presented. |
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| ASSESS OF THE EXCAVATION PLAN OF A LARGE-AREA FOUNDATION ON GRAVALLY SANDY SOIL |
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| 張瑞仁、謝孟達、王柏雁 |
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| 砂礫土層，地下室開挖，連續壁，扶壁 |
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| 砂礫土層因級配組成可使其摩擦角較粉質砂土為高，但因無法確知級配特性的效應，在估算摩擦角時仍多採用較保守的數值。砂礫土層也是滲透性良好的地層，進行地下室開挖與基礎工程時，開挖工法之規劃必需考慮基地內外抽水的影響。在大面積基礎工程，必需詳加考量安全措施工法之可行性。由於基地幅員廣大，結構體多採分區構築，各分區間界面之整合，同時進行結構與開挖施工，是工程管理上一大挑戰。本文就南部砂礫地層上，一廣達近40000平方公尺的基地，工法規劃與施工過程，所面臨的相關問題，作一說明。該基地一側長約350m且與約70棟3層樓建築相鄰，採用連續壁配合扶壁為全區擋土結構，使基地內得以形成無支撐開挖環境。從此一實例得知，砂礫土層之強度依據其級配特性可有更合理之估算；自監測結果觀察，此類型擋土措施在砂礫土層中，能發揮良好的擋土效果，滿足安全維護及工作性的要求。 |
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| Gravelly sandy soil has largle friction angel than general silty sand because of the well-graded effect. But due to lack of proper estimation of this effect, friction angle of gravelly sandy soil is usually calculated conservatively. With high permeability, the influence of pumping should be considered in the excavation plan in gravelly sandy soil. For the large-area foundation work, the workability of the excavation and construction method should be assessed very carefully. This paper will discuss some of the problems encountered during excavation process in gravelly sandy soil, in a site with an area of about 40,000m2 in southern Taiwan. There are 70 buildings along the eastern perimeter of this site about 350m in length. Using a slurry wall with a buttress structure as the retaining system will allow the excavation work to proceed without installation of inner struts. This practical case study shows the shear strength of well-graded gravelly sandy soil will be calculated more properly. Such a kind of retaining structure works well to fill both the workability and safety requirements. |
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| THE NUMERICAL ANALYSIS OF RETAINING WALL DRAINING |
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| 李煜舲 |
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| 汲水孔、排水層、水力傳導係數、有限元素分析、流線網 |
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| 關於擋土牆排水設施功能之研究，其影響因素包含牆背後排水層之厚度與長度、水力傳導係數和土壤孔隙率等，藉由分析結果探討土壤內部之水頭、水力梯度、孔隙水壓和流量等變化量，以期提供設計參考之用，即為本文主要的研究目的。研究內容包含以有限元素分析程式模擬土壤排水之流線網分析，並解決三種排水設施之邊界值問題，包括牆身汲水孔排水法、貼牆直立式排水層加上牆身汲水孔排水法，以及水平式排水層法等。經由數值計算與分析結果得知，採用水平式排水層法能獲得較大之排水範圍，並能提供低水頭和高排水量之功能，其中排水層長度為主要影響因素；最後，提出三種排水設施參考用之孔隙水壓設計建議值。 |
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| The influence of retaining wall draining facility on drainage is investigated in this research. The effects of retaining wall draining are taken into account the draining blanket, coefficient of hydraulic conductivity and soil porosity. The object of this study is related to the flow of water through soil that includes the head drop, hydraulic gradient, pore water pressure and flow rate. The finite element program is utilized to simulate the boundary value problem of retaining wall draining facility that includes three kinds of drainage facility, weep holes, weep holes with vertical draining blanket, and weep holes with horizontal draining blanket. According to results obtained, if the wall-back water level is quite high, horizontal draining blanket has the effort on reducing the water level and can drain more water. Finally, the values of pore pressure for the design of three kinds of drainage facility are proposed. |
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| VIBRATION IMPACT EVALUATION AND MITIGATION MEASURES FOR PILE DRIVING |
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| 余明山、王鴻基、鍾毓東 |
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| 打樁振動、容許振動量、振動防治對策 |
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| 振動是打擊式樁基礎施工過程中一項令人困擾之問題，打樁伴隨產生之顯著振動常招致鄰近居民之抱怨，嚴重時甚至造成房屋、設備毀損，因此打樁振動之影響評估與相關防治對策之研擬，為採行打擊式基樁前必要之評估程序。我國環保署刻正致力於相關振動法規之制定，但尚未頒佈。因此，從事設計或現場施工的工程師常感無所遵循。本文即整理各國法規及專家對允許振動量之規定或建議，並就打樁工程可能引致之振動量評估及工程技術上可行之振動防治對策，作一介紹，期供工程界同仁參考。 |
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| Vibration associated with pile driving activities, during the construction operations, is frequently annoying the nearby neighbors and causes damages on surrounding buildings or interference with the operation of sensitive equipment. Therefore, the assessment of vibration impacts and mitigation measures should be identified before pile driving. However, there is no local regulation or code available for designers and engineers at this moment. In this paper, several codes and standers associated with vibration criteria and feasible measures for vibration evaluation and mitigation are introduced for reference. |
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