https://scholars.lib.ntu.edu.tw/handle/123456789/169473
標題: | 台灣地區造震斷層摩擦組成律及其應用-以車籠埔斷層為例 A study on laboratory-derived friction laws and their application to seismic faulting in Taiwan (I) |
作者: | 林銘郎 | 關鍵字: | 斷層泥;摩擦組成率;停滯時間;沉降法;fault gouge;friction law;holding time;slide-hold-slide tests;velocity stepping tests | 公開日期: | 2005 | 出版社: | 臺北市:國立臺灣大學土木工程學系暨研究所 | 摘要: | 台灣位於活動地體構造,全島多斷層和 破碎帶,由於斷層錯動所引發之地震,其震 源較淺,且距都會區較近,其所造成之災害 亦較為嚴重。Dieterich 及Ruina 等人(1994), 研究斷層泥之摩擦特性,結合速率與狀態參 數,提出摩擦組成律。此組成律提供了研究 地震之相當實用的解釋工具。由現地觀察之 震前移動、能量集結、同震破裂、與震後變形等現象,均可利用摩擦律來解釋。 由於國外研究多以花崗岩顆粒或是石 英砂等粒狀材料進行試驗,而台灣地區之斷 層泥則以黏土質或是沉積岩剪碎或風化後之 產物為主,因此,須對台灣地區之斷層泥摩 擦特性作一個探討,由於其斷層泥細料含量 較高,不易透水,在斷層錯動之過程中,其 所夾之斷層泥可能累積大量之孔隙水壓,進 而影響其有效應力,因此,有必要進行有效應力分析。 本研究選取車籠埔沿線挖溝所得斷層泥 以沉降法製作重模之斷層泥試體。並改良一 般三軸試驗之設備以利進行夾泥之三軸試 驗,並在剪動過程中量測孔隙水壓,以進行 有效應力分析。探討斷層泥癒合作用之機制 與總應力分析以及有效應力分析對摩擦組成律之影響。 本研究結果顯示以沉降法製作斷層泥 試體,可製作出具有飽和、優選排列之試體, 使得在試驗過程中,其穩定剪動時之摩擦係數可以控制在一定範圍內。錯動-停滯-錯 動試驗中,孔隙水壓之激發為影響有效摩擦 係數之主因。而有效摩擦係數隨停滯時間之 對數值之增加而有線性上升之趨勢,在不同 加壓速率下是影響摩擦係數上升值之主因。 而在變速率夾泥三軸試驗中,在超額孔隙水 壓與軸向位移關係中,在慢剪時會激發較高 之孔隙水壓而在快剪所激發之水壓相對較 小,經研判認為在慢剪時會有受壓密實之現 象,而快剪由於會造成試體拉伸而使孔隙增 加,進而使孔隙水壓較小。 Base on the combination of the Eurasia and Philippine plate forms the Taiwan Island, the disaster which is induced by fault movement will be serious because the earthquake focus is quit shallow and near the city. The study of the friction characteristic of the fault gouge is proposed by Dieterich, etc(1994) that combines the speed and the state parameter to propose the friction law. This friction law offers a quite practical method to study the earthquake. To explain the friction law, most of the existing experimental studies use the granular materials such as the granite particle and the quartz sand. Most faults in western Taiwan contain fault gouges, including Chelungpu Fault, so that this research focuses on the technical practicability to find out the effect of clayey gouge and some other factors which may control the slip stability. This approach shows that the insight conclude the underlying physics of a specific fault and the parameters into the following rules. Two main experiments are performed, there are Slide-Hold-Slide tests (SHS tests) and Velocity Stepping tests (VS tests), to determine some friction parameters and to establish the relation between different parameters in the friction law. The experiments are carried out by using triaxial apparatus on a 5mm-thick gouge layer of remolded fault clayey gouge. Slide-Hold-Slide tests are driven at a constant velocity for each test, and it keeps a given interval to restart at the driving velocities. The results indicate that (1) the static friction (healing) μsand the friction relaxation are linearly increased with log-hold-time during the quasi-stationary contact; (2) the fast slip produces would have large static friction for a given contact time, but the rate of healing β would maintain constant at different operating rates of displacements; (3) the drained volume Δv is increased as the holding time in the sample compression, and this behavior is similar to the consolidation of soil mechanics. For the Velocity Stepping tests, the effects on the friction parameters are discussed by varying the ratios of steps depending on velocity (10~ 400), load velocity (0.005~5 mm/min), and the accumulated slip in velocity stepping tests. The results indicate that (1) the frictional stability (a-b) is decreasing with shear strain, and the positive value of (a-b) leads the fault gauge to be “velocity-strengthening” behavior, which is intrinsically stable; (2) frictional parameters a, b, and (a-b) are not major influence of velocity; (3) the critical slide distance Dc decreases with the increasing ratio of the velocity steps. Furthermore, the friction law is verified and suitable for this research, and the fitting curve from the experimental results has good R-squared values. Finally, the relations between parameters b=βln(10)and (a-b)=dμd/d V are also established. |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/2893 | 其他識別: | 932211E002039 | Rights: | 國立臺灣大學土木工程學系暨研究所 |
顯示於: | 土木工程學系 |
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