Study on the Application of Rockmass Discontinuum Model on Granular Debris Flows

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基本資料

Project title

Code/計畫編號

NSC99-2628-E019-006

Translated Name/計畫中文名

岩盤工程非連續體數值模式應用於礫石型土石流問題之研究

Project Coordinator/計畫主持人

Cheng-Yu Ku

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Harbor and River Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=2114374

Year

2010

Start date/計畫起

01-08-2010

Expected Completion/計畫迄

31-07-2011

Bugetid/研究經費

572千元

ResearchField/研究領域

土木水利工程

"台灣地區由於受到板塊擠壓，造就出陡峻的地形與脆弱多變的地質環境，破碎之地層造成斷層、層面、節理、張裂縫、或剪裂縫等弱面幾乎無所不在，於自集集地震後，台灣山區岩體受到劇烈擾動而更加破碎，近幾年來數次的颱風事件，經常導致山區發生大規模的山崩與土石流，導致各地的受災範圍與程度均遠較過去為烈，嚴重地危害到民眾生命與財產的安全。尤其是2008 年間之薔蜜、辛樂克、卡玫基颱風等在台灣北中南地區均造成嚴重之崩塌與土石流災害。而民國2009 年8 月8 日莫拉克颱風來襲，更造成南台灣包含南投、高雄、與屏東等縣市嚴重的災害，此次莫拉克颱風所造成人員與設施的傷亡災害，為歷年罕見，兩千多公厘之豪大降雨量造成南台灣地區多處崩塌、土石流、堰塞湖潰堤、洪水等災害。傳統以連續體觀念發展之分析方法對台灣地區破碎岩盤問題之適用性受到相當之侷限，諸如中部地區大甲溪流域嚴重之崩塌、落石與土石流問題，或是邊坡發生崩塌後，其崩塌材料之移動範圍與可能影響範圍等，因此針對裂隙岩體等非連續體問題發展合適台灣地區之非連續體分析模式有相當之必要性。本研究將以非連續體顆粒力學方法進行土石流運動機制之研究，非連續體顆粒力學方法將土石流視為不連續體，土石流之組成為許多不連續的顆粒材料堆積，於土石流運行中，土石顆粒間可允許大變位及錯動，較適合台灣地區多以礫石為主體之土石流運動型式。前人研究成果顯示，非連續體分析模式可考慮塊體間接觸與碰撞之力學特性，對於落石與土石流等大變形問題之分析有其優越性。本研究計畫擬以不連續變形分析法為理論發展以不連續變形分析法(Discontinuous Deformation Analysis, DDA)為理論之岩體工程非連續體數值分析方法，除修改DDA 理論與分析方法之相關限制外，並進一步推導理論與撰寫分析程式，申請者於先前計畫中已初步完成顆粒版本之不連續變形分析法理論與分析程式。本年度擬進一步引入擬時間積分法(Fictitious Time Integration Method, FTIM)，藉由FTIM 處理病態問題之優越能力與抗噪之特性，嘗試與DDA 方法進行結合，以其改良DDA 於處理土石流顆粒間之剛性接觸碰撞問題所引致之病態問題，進一步改良DDA 法數值計算之穩定度，之後再進一步將流體機制與不連續變形分析法進行結合，並推導流體機制與不連續塊體顆粒間之力學互制關係，最後將本研究所建立之理論與分析程式應用於土石流問題之運動機制之研究。" "Taiwan is an active mountain belt created by the oblique collision between the northern Luzon arc and the Asian continental margin. The inherent complexities of geological natural creates numerous discontinuities through rock masses in this area, which exist in many forms such as fissures, cleavages, beddings, joints, and even faults and dominate the behaviour of jointed rock masses. Along the past decades, the hazards of debris flow triggered by earthquake activities and heavy rainfalls occur frequently in Taiwan. The Chi-Chi earthquake and the following several typhoon events, especially the 88 flooding hazard, in particular triggered hazards including landslides, debris flows, and floods which caused significant property damage and inflicted heavy casualties. In addition, in recent years, the increase in the frequency and intensity of extreme natural events due to global warming or climate change brought significant landslide and debris flow hazards. Accordingly, the study on the development of discontinuum model for dealing with the landslide and debris flow hazards is essential. It also stimulates the study for exploring the initiation and mechanism of the granular debris flow to further understand the debris flow behaviour. The continuum approach uses mainly the finite element method as the backbone. It relies either on the adoption of an equivalent continuum for a jointed rock mass, or on treating discontinuities as added interface. An equivalent continuum approach lacks the capability in capturing the overall kinematics of a jointed rock mass from discontinuities. The discontinuum approach, on the other hand, considers a rock mass delineated by joints as blocks, and is capable of capturing of kinematics of the block system. It demonstrates a great potential in modeling the jointed rock mass problems. Based on the observation from colluviums of conglomerate formation in central and east Taiwan, it is found that the granular debris flow is the major type in these areas. However, most of the methods mentioned above were based on the continuum mechanics which lacks of the mechanics for describing the behaviour of the stony debris flow or the granular flow. In this proposed study, the Discontinuous Deformation Analysis (DDA) is adopted to study the initiation and mechanism of the granular debris flow. The incorporation of the effects of fluid flow into the DDA and the adoption of the Fictitious Time Integration Method, FTIM for establishing the methodology and code is presented in this study. It is expected that the DDA method can be a useful tool to model the initiation and mechanism of the granular debris flow based on the discontinuum mechanics with emphasis on the particle mechanics for more realistically studying the debris flow problem."

Keyword(s)

土石流
顆粒力學
不連續變形分析法
接觸碰撞
擬時間動力分析法
Debris Flow
Granular
Discontinuous Deformation Analysis
Contacts
Dynamical Newton-like Method

DSpace CRIS

Study on the Application of Rockmass Discontinuum Model on Granular Debris Flows

基本資料

Description