【摘要】：斷層粘滑過程的差應(yīng)力-時間曲線可以分成線性、偏離線性、亞失穩(wěn)和失穩(wěn)四個階段。亞失穩(wěn)階段是指差應(yīng)力從峰值時刻到產(chǎn)生快速應(yīng)力降起始時刻之間的階段,也是斷層失穩(wěn)之前的最后階段。利用在實驗室既能通過壓機觀測到標(biāo)本應(yīng)力狀態(tài),又能使用多物理場觀測手段獲取標(biāo)本表面變形信息的優(yōu)勢,通過分析標(biāo)本表面全場變形的時空演化,尋找識別標(biāo)本進入亞失穩(wěn)階段的標(biāo)志,有助于分析野外斷層所處的應(yīng)力狀態(tài),進而判斷地震危險時刻是否臨近。本文以斷層粘滑過程變形場的時空演化作為研究對象,采用高速相機采集標(biāo)本變形圖像,運用數(shù)字圖像相關(guān)方法為主要分析手段,結(jié)合其他物理場觀測手段(如應(yīng)變片、聲發(fā)射等),研究了不同加載速率下含平直斷層的花崗閃長巖標(biāo)本的變形時空演化特征。此外,基于粘土材料對基底斷層活動引起蓋層變形場演化的過程進行了模擬。取得的主要認識如下：(1)斷層局部預(yù)滑區(qū)的加速擴展是斷層進入亞失穩(wěn)階段的標(biāo)志之一。標(biāo)本通過斷層局部預(yù)滑釋放應(yīng)力,在偏離線性階段標(biāo)本應(yīng)力以積累為主釋放為輔,局部預(yù)滑區(qū)開始出現(xiàn),進入亞失穩(wěn)階段后標(biāo)本以應(yīng)力釋放為主并從平穩(wěn)釋放向加速釋放轉(zhuǎn)變,局部預(yù)滑區(qū)也同時出現(xiàn)明顯的加速擴展。采用斷層局部預(yù)滑區(qū)歸一化長度(W)隨時間的變化對局部預(yù)滑區(qū)的擴展程度進行定量分析,結(jié)果表明W的曲率峰值時刻可作為斷層進入亞失穩(wěn)階段的近似識別標(biāo)志。(2)斷層各部位位移方向趨向一致過程的加速是斷層進入亞失穩(wěn)階段的另一標(biāo)志。采用度量斷層位移方向空間分布無序程度的斷層位移方向歸一化信息熵(S)隨時間的變化進行定量分析,結(jié)果表明S的曲率峰值時刻可作為斷層進入亞失穩(wěn)階段的另一近似識別標(biāo)志。(3)亞失穩(wěn)階段后期觀測到應(yīng)變的條帶狀分布和動態(tài)傳遞過程。通過對樣品的全場應(yīng)變高速采樣觀測(空間分辨率0.15mm,時間分辨率1ms),發(fā)現(xiàn)亞失穩(wěn)階段后期平行于斷層的應(yīng)變和體應(yīng)變呈條帶狀分布和動態(tài)傳遞的現(xiàn)象。結(jié)合早期應(yīng)變片觀測結(jié)果,分析此類應(yīng)變波隨著失穩(wěn)的臨近存在頻率加快、幅度增大并向震源初始破裂位置傳遞的特點。對這個現(xiàn)象的進一步研究將有助于認識人們在地震前發(fā)現(xiàn)并討論的前兆波現(xiàn)象。(4)蓋層變形模式受基底斷層活動方式控制�；讛鄬踊顒右鹕细采w層中出現(xiàn)盆地系,這些盆地變形過程可分為初始的獨立擴展與后期的相互作用兩個階段。通過分析蓋層變形了解基底斷層的活動性質(zhì),有助于進一步通過蓋層變形研究基底斷層的亞失穩(wěn)階段。
[Abstract]:The stress-time curves of the slip process can be divided into four stages: linear, deviating from linearity, sub-instability and instability. The metastable phase is the phase from the peak moment to the beginning of the rapid stress drop, and the last stage before the fault instability. Using the advantage that the stress state of the specimen can be observed by the press in the laboratory and the deformation information of the specimen surface can be obtained by the means of multi-physical field observation, the space-time evolution of the full-field deformation of the specimen surface is analyzed. It is helpful to analyze the stress state of the field fault and to judge whether the seismic danger time is approaching or not. In this paper, the spatiotemporal evolution of the deformation field in the process of fault stick-slip is taken as the research object, the deformation images of the specimen are collected by high-speed camera, the digital image correlation method is used as the main analysis means, and other physical field observation methods (such as strain gauge) are combined. The temporal and spatial evolution characteristics of deformation of granodiorite specimens with flat faults at different loading rates were studied. In addition, the evolution process of deformation field of caprock caused by basement fault activity is simulated based on clay material. The main results are as follows: (1) the accelerated expansion of the local preslip zone is one of the indicators of the fault entering the stage of sub-instability. The specimen was released by local pre-slip through the fault, the stress was mainly released by accumulation in deviation from the linear phase, and the local preslip began to appear. After entering the sub-unstable stage, the specimen mainly released stress and changed from steady release to accelerated release. At the same time, the local preslip area also appears obvious acceleration expansion. The extension degree of local preslip zone is quantitatively analyzed by using the variation of normalized length (W) with time in the local preslip zone of fault. The results show that the peak moment of curvature of W can be used as an approximate identification marker for the fault to enter the stage of sub-instability. (2) the acceleration of the direction of displacement in each part of the fault is another sign for the fault to enter the stage of sub-instability. The normalized information entropy (S) of fault displacement direction, which is used to measure the disordered degree of spatial distribution of fault displacement direction, is used to quantitatively analyze the change of information entropy with time. The results show that the curvature peak time of S can be used as another approximate identification marker for the fault to enter the stage of sub-instability. (3) the strip distribution and dynamic transfer process of strain are observed in the later stage of sub-instability. Based on the high speed sampling of the whole field strain (spatial resolution 0. 15 mm, time resolution 1ms), it is found that the strain and volume strain parallel to the fault in the later stage of subinstability are striped and dynamically transmitted. Based on the results of early strain gauge observations, the characteristics of such a strain wave are analyzed as the frequency of instability approaches to accelerate, the amplitude increases and the strain wave propagates to the initial rupture location of the source. Further study of this phenomenon will be helpful to understand the phenomenon of precursor wave discovered and discussed before the earthquake. (4) the deformation model of caprock is controlled by the mode of basement fault activity. The basin system appears in the overburden caused by the basement fault activity. These basin deformation processes can be divided into two stages: the initial independent extension and the late interaction. By analyzing the deformation of the caprock to understand the active properties of the basement fault, it is helpful to study the sub-instability stage of the basement fault through the deformation of the caprock.
【學(xué)位授予單位】：中國地震局地質(zhì)研究所
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：P315.2

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