本文關(guān)鍵詞：龍門山斷裂帶斷層泥中速—高速摩擦性質(zhì)的實(shí)驗(yàn)研究　出處：《中國(guó)地震局地質(zhì)研究所》2013年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 中-高速摩擦性質(zhì) 龍門山斷裂帶 汶川地震 滑動(dòng)弱化 滑動(dòng)弱化機(jī)制 納米顆粒(粉末)潤(rùn)滑 滑移-保持-滑移實(shí)驗(yàn) 斷層強(qiáng)度恢復(fù) 愈合率 巖石摩擦速度依賴性

【摘要】：為了認(rèn)識(shí)龍門山斷裂帶在汶川地震中的同震滑動(dòng)力學(xué)性質(zhì)，我們對(duì)龍門山斷裂帶地表斷層帶露頭上的斷層泥及少量WFSD-1斷層泥開展了中速-高速摩擦實(shí)驗(yàn)研究。主要關(guān)注的問題包括：龍門山斷裂帶高速摩擦性質(zhì)及其不均勻性、震后斷層強(qiáng)度恢復(fù)問題、高速滑動(dòng)可能的主導(dǎo)弱化機(jī)制問題和寬速度域內(nèi)摩擦滑動(dòng)速度依賴性問題。 基于對(duì)斷層帶結(jié)構(gòu)和斷層巖樣品的精細(xì)分析，我們從礦坪子和八角廟斷層帶露頭采集了四種斷層泥樣品。對(duì)這些樣品及另外三種WFSD-1樣品開展的高速摩擦實(shí)驗(yàn)揭示除了礦坪子露頭黑色斷層泥，其他幾種斷層泥的高速摩擦性狀均表現(xiàn)為負(fù)指數(shù)衰減型滑動(dòng)弱化。礦坪子露頭黑色斷層泥具有非常獨(dú)特的力學(xué)性狀：初始階段快速的滑移弱化，接著出現(xiàn)微弱的滑移強(qiáng)化至第二個(gè)峰值，之后逐漸弱化至穩(wěn)態(tài)。微結(jié)構(gòu)觀察和對(duì)比實(shí)驗(yàn)表明初始快速弱化和之后的微弱強(qiáng)化主要是黑色斷層泥特殊的微結(jié)構(gòu)演化造成的�；诮�(jīng)驗(yàn)公式和進(jìn)一步的推導(dǎo)，我們選取了六個(gè)能夠描述穩(wěn)態(tài)摩擦系數(shù)、滑動(dòng)弱化距離和比破裂能對(duì)速率和正應(yīng)力依賴性的本構(gòu)參數(shù)。我們對(duì)本論文和前人研究過的四個(gè)露頭共計(jì)六種斷層泥的高速摩擦性質(zhì)進(jìn)行了比較，從這上述六個(gè)本構(gòu)參數(shù)的定量化比較來看，龍門山斷裂帶高速摩擦性質(zhì)的不均勻性是存在的。不過，如果僅僅是考察摩擦強(qiáng)度，高速滑移下的穩(wěn)態(tài)摩擦系數(shù)在整個(gè)斷層帶上的均勻性還是相當(dāng)高的；如干燥條件下速率等于1.4m/s時(shí)幾乎均小于0.2，在含水條件下還將更低。這些斷層泥在高速滑移下顯著的滑移弱化必定在汶川地震中極大地促進(jìn)了破裂的傳播，也能夠解釋震后鉆探觀測(cè)到的溫度異常較小的現(xiàn)象。 高速滑移下的slide-hold-slide實(shí)驗(yàn)揭示斷層在經(jīng)歷高速滑移顯著滑移弱化之后，能夠在5~10s內(nèi)快速恢復(fù)大部分的強(qiáng)度(摩擦系數(shù)增加約0.4)，愈合率(摩擦系數(shù)增量與保持時(shí)間對(duì)數(shù)的比值)達(dá)0.154~0.188；之后是跟時(shí)間對(duì)數(shù)成正比的緩慢愈合，愈合率約0.015~0.016。溫度計(jì)算表明初始快速的強(qiáng)度恢復(fù)和溫度的快速降低有關(guān)。5~10s的強(qiáng)度恢復(fù)時(shí)間尺度小于一般大地震的上升時(shí)間，從而支持自愈合滑動(dòng)脈沖式的地震破裂模式。同時(shí)，斷層高速滑移之后快速的強(qiáng)度恢復(fù)對(duì)穩(wěn)定斷層的摩擦滑動(dòng)、減少余震也可能起到了重要作用。 對(duì)極薄(0.1~0.14mm)和常規(guī)厚度斷層泥(1.0~1.4mm)開展的中速-高速摩擦對(duì)比實(shí)驗(yàn)揭示薄層斷層泥的剪切滑移能夠更快地弱化斷層，而且斷層顯著滑動(dòng)弱化的特征滑動(dòng)速率也低得多；微結(jié)構(gòu)觀察表明這可能是凹凸體急劇加熱弱化機(jī)制在薄層斷層泥實(shí)驗(yàn)中更加顯著造成的；極薄和較厚斷層泥高速摩擦性狀的差異可能暗示著野外斷層上相對(duì)更薄的斷層泥層能夠更快地在同震滑移中弱化斷層、也能更大程度地促進(jìn)地震破裂的傳播。利用輝長(zhǎng)巖和黃銅作圍巖開展的高速摩擦對(duì)比實(shí)驗(yàn)揭示黃銅作圍巖的實(shí)驗(yàn)中僅觀察到微弱的滑動(dòng)弱化，溫度計(jì)算表明這與黃銅的高熱導(dǎo)抑制了斷層帶的急劇升溫有關(guān)，這暗示了凹凸體急劇加熱弱化和熱壓作用這兩種跟摩擦生熱相關(guān)的機(jī)制對(duì)斷層弱化的重要性。利用黃銅作圍巖對(duì)納米氧化鎂開展的高速摩擦實(shí)驗(yàn)表明，在升溫受抑制的情況下，即使是純納米顆粒物質(zhì)也不能有效地顯著弱化斷層；這一結(jié)果表明納米顆粒的滾動(dòng)潤(rùn)滑機(jī)制不是斷層高速滑動(dòng)弱化的主要機(jī)制。 對(duì)斷層泥從低速到高速開展的摩擦實(shí)驗(yàn)研究表明，中等速率域內(nèi)顯著的速度強(qiáng)化是有可能存在的。但是實(shí)驗(yàn)同時(shí)揭示數(shù)百μm/s以下的摩擦滑動(dòng)在大剪切應(yīng)變下(如,1000)存在顯著的應(yīng)變硬化(滑移強(qiáng)化)，這可能與斷層泥在大應(yīng)變下發(fā)生的物質(zhì)和結(jié)構(gòu)上的改變有關(guān)，今后對(duì)寬速度域內(nèi)摩擦滑動(dòng)速度依賴性進(jìn)行研究時(shí)，，需要充分考慮應(yīng)變硬化帶來的影響。
[Abstract]:In order to bring the coseismic slip properties in Wenchuan earthquake in the Longmen Mountain Fault Zone understanding, outcrop on the fault gouge of mud and a small amount of WFSD-1 we surface faults of Longmen mountain fracture experiment of high-speed friction speed. The main concern include: uneven and high speed friction properties of the Longmen Mountain Fault Zone, the problem after the earthquake fault recovery strength, leading high-speed sliding possible Weakening Mechanism Problems and wide speed domain sliding speed dependent problem.
Fine analysis of fault zone structure and fault rock samples based on us from the mine and the octagonal Temple Ping Zi fault outcrop collected four species of fault gouge samples. These samples and other three samples to carry out the high speed friction experiment of WFSD-1 revealed in addition to mine Ping Zi outcrop black gouge, which he gouge several high-speed friction sliding type traits showed that the exponential decay weakened. Ore Ping Zi black gouge with outcrop mechanical properties is very unique: slip weakening fast initial stage, then the weak slip to strengthen the second peak, then gradually weakened to a steady state. The micro structure observation and experiments show that after the initial rapid weakening and strengthening weak the black gouge is mainly caused by the special micro structure evolution. And further deduced based on empirical formula, we selected six to describe the steady friction coefficient, sliding weak The distance and the rupture rate and is the ratio of the stress dependence of the constitutive parameters. In this paper we four outcrop and previous research had a total of six kinds of fault gouge and high speed friction properties were compared, from the comparison of the six constitutive parameters of quantification, inhomogeneity of high-speed friction properties the Longmen mountain fault zone is there. However, if only to study friction strength, steady friction coefficient of sliding speed is quite high in the uniformity of the whole fault zone on the dry conditions; such as the 1.4m/s rate is equal to almost all less than 0.2, under Hydrous conditions will also lower. The fault gouge slip significantly in high speed slip weakening in the earthquake in Wenchuan will greatly promote the propagation of the rupture, can also explain the abnormal temperature smaller after drilling of the observed phenomenon.
Slide-hold-slide experiment of high speed of sliding fault after weakening speed revealed significant slip slip, can quickly restore most of the strength in 5~10s (friction coefficient increased about 0.4), the healing rate (the ratio of friction coefficient increment and keep the logarithm of time) of 0.154~ 0.188; followed with time is proportional to the logarithm of the slow healing, healing rate about 0.015~0.016. temperature calculation showed that the initial rapid recovery and the rapid decrease of temperature strength on.5~10s strength recovery time scale is less than the rise time of the earthquake, so as to support the self-healing slip pulse type earthquake rupture model. At the same time, the rapid recovery of strength of sliding friction stability after fault fault slip speed, reduce the aftershocks may played an important role.
The thin thickness (0.1~0.14mm) and conventional fault gouge (1.0~1.4mm) carry out medium - speed friction experiments reveal the shear slip fault gouge layer can be rapidly weakening fault slip rate and characteristics of fault slip weakening was much lower; micro structure observation show that the asperity may be more significant weakening mechanism of rapid heating result in thin gouge experiment; thin and thick difference gouge high-speed friction traits suggests that fault gouge layer field relatively thinner faster in the coseismic slip of weak fault, can greatly promote the spread of earthquake rupture. By contrast experiment of high-speed gabbro and brass the friction surrounding rock revealed brass experiments were observed only in the weak slip weakening, temperature calculation shows that high thermal conductivity and the sharp brass suppression of the fault zone The temperature, suggesting that the asperity rapid heating and hot pressing the weakening effect of these two related to friction mechanism of the importance of fault weakening. Using brass rock on high speed friction experiment of nano Magnesium Oxide carried out shows that during the heating by inhibiting the case, even the pure nano particles can effectively weaken significantly fault the results show that the main mechanism; the weakening of rolling lubrication mechanism of nano particles is not fault high-speed sliding.
Study on friction experiment of fault gouge from low speed to high speed development, the medium rate domain significantly enhanced speed is possible. But the experiments also revealed hundreds of m/s friction in the sliding shear strain (e.g., 1000) there is significant strain hardening (slip strengthening), material and structure a possible fault gouge under large strain on the change, the future of wide speed domain sliding speed dependent study, need to fully consider the influence of strain hardening brings.

【學(xué)位授予單位】：中國(guó)地震局地質(zhì)研究所
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU45;P315

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