葉巴灘水電站壩址區(qū)“砂糖狀”擠壓破碎帶蝕變礦物巖石學(xué)特征及成因分析
發(fā)布時間：2018-12-27 13:36
【摘要】：受區(qū)域構(gòu)造作用影響,歐亞板塊與印度板塊間三江構(gòu)造帶內(nèi),廣泛發(fā)育的擠壓破碎帶,已成為制約我國大型水電站建設(shè)和運營的主要工程地質(zhì)問題。深入研究金沙江葉巴灘水電站壩址區(qū)“砂糖狀”擠壓破碎帶的基本特征、類型及形成原因,為進(jìn)一步評價“砂糖狀”擠壓破碎帶巖體質(zhì)量及可利用性奠定基礎(chǔ)。基于野外調(diào)查、掃描電鏡(SEM)、X射線粉晶衍射(XRD)和地球化學(xué)測試等方法,揭示“砂糖狀”擠壓破碎帶的宏觀地質(zhì)特征與蝕變礦物巖石學(xué)特征,劃分蝕變類型,探討“砂糖狀”擠壓破碎帶的控制因素與演化過程。研究表明:(1)“砂糖狀”擠壓破碎帶集中位于2790~2850m范圍,隨高程變化規(guī)律不明顯;左岸“砂糖狀”擠壓破碎帶分布范圍廣、數(shù)量多,右岸“砂糖狀”擠壓破碎帶集中發(fā)育在常規(guī)風(fēng)化卸荷帶,微新巖體中較少揭露此類特殊的地質(zhì)現(xiàn)象,水平和垂向分布范圍均小于左岸;“砂糖狀”擠壓破碎帶發(fā)育深度具有隨切割深度、坡形轉(zhuǎn)折程度增大而加深的規(guī)律。(2)“砂糖狀”擠壓破碎帶大多繼承早期構(gòu)造節(jié)理形成,力學(xué)特性呈剪性;“砂糖狀”擠壓破碎帶總體呈弱透水性,在局部構(gòu)造或裂隙密集帶透水性會增強(qiáng);中高程的透水率往往比低高程透水率大,具有隨埋深的增大,透水率逐漸減少的規(guī)律。(3)觀察石英形貌特征可得壩址區(qū)“砂糖狀”擠壓破碎帶中,石英形貌結(jié)構(gòu)有貝殼狀、次貝殼狀、桔皮狀、苔蘚狀和蟲蛀狀5種類型;左岸石英顆粒經(jīng)歷的溶蝕時間、溶蝕結(jié)構(gòu)的復(fù)雜程度大致與高程呈正相關(guān);強(qiáng)弱卸荷帶以里的“砂糖狀”擠壓破碎帶中石英顆粒表面具有粘滑的應(yīng)力痕跡;“砂糖狀”擠壓破碎帶錯動主要發(fā)生在中更新世~晚更新世。(4)壩址區(qū)蝕變是多期次的,蝕變產(chǎn)物形成的階段不同,溫度變化幅度大,與圍巖接觸的動力流體為富鎂鐵的氧化流體;“砂糖狀”擠壓破碎帶內(nèi)巖石富鋁貧堿,這與斜長石的大量分解,淺色云母等新生礦物的形成有關(guān);同一平硐中主量元素的變化表明,斷裂構(gòu)造對主量元素的重新分配具有明顯控制作用。(5)結(jié)合蝕變作用的疊加,根據(jù)蝕變溫度、破碎帶寬度、破碎帶內(nèi)物質(zhì)的顏色、風(fēng)化狀態(tài)以及地下水作用,將“砂糖狀”擠壓破碎帶劃分為輕微蝕變型、中等蝕變型、強(qiáng)烈蝕變型;不同蝕變類型是高溫型~低溫型動力構(gòu)造蝕變與次生風(fēng)化蝕變的不同組合疊加構(gòu)成。(6)壩址區(qū)特有的巖性、地質(zhì)構(gòu)造與巖體結(jié)構(gòu)條件為“砂糖狀”擠壓破碎帶的形成提供物質(zhì)和結(jié)構(gòu)基礎(chǔ);河谷的快速下切造成岸坡巖體內(nèi)部高應(yīng)變能強(qiáng)烈釋放,邊坡巖體向臨空方向發(fā)生卸荷回彈,形成“砂糖狀”擠壓破碎帶,并產(chǎn)生構(gòu)造動力蝕變,與圍巖接觸的動力熱流溫度由高到低,形成輕微蝕變型和中等蝕變型;經(jīng)后期地下水的改造作用,局部風(fēng)化加劇,帶內(nèi)疊加形成次生風(fēng)化蝕變。
[Abstract]:Under the influence of regional tectonics, the compressional fracture zone, which is widely developed in the Sanjiang tectonic belt between Eurasian plate and Indian plate, has become the main engineering geological problem restricting the construction and operation of large hydropower stations in China. The basic characteristics, types and causes of the "sucrose" crush fracture zone in the dam site of Yipatan Hydropower Station on the Jinsha River are studied in depth, which lays a foundation for further evaluation of the quality and availability of the rock mass in the "Sugar" crush fracture zone. Based on field investigation, scanning electron microscope (SEM), X) ray powder diffraction (XRD) and geochemical measurement, the macroscopic geological characteristics and altered mineral petrological characteristics of the "Sugar" crush fracture zone are revealed, and the alteration types are classified. The controlling factors and evolution process of sugary crush zone are discussed. The results show that: (1) the "sugary" crushing zone is located in the range of 2790 ~ 2850 m, and the rule of variation with elevation is not obvious; On the left bank, the "Sugar" crush fracture zone has a wide distribution range and a large number. On the right bank, the "Sugar shaped" crush crushing zone is concentrated in the conventional weathering and unloading zone, and the special geological phenomena are seldom revealed in the micro-new rock mass. The horizontal and vertical distribution range is smaller than the left bank; The depth of development of "Sugar" crush fracture zone has the law of deepening with cutting depth and slope turning degree. (2) most of "Sugar" crush fracture zone inherits early structural joints, and its mechanical properties are shearing; The "sugary" crushing zone is weak permeable in general, and will be enhanced in local structure or fissured dense zone. The permeability of medium elevation is usually higher than that of low elevation, and the permeability decreases gradually with the increase of buried depth. (3) observing the morphology characteristics of quartz, we can find that the structure of quartz is shell-like in the "sugary" crush crushing zone of dam site area. There are 5 types of secondary shell, orange peel, moss and insect moths; The dissolution time of quartz particles on the left bank and the complexity of the dissolution structure are positively correlated with the elevation, and the surface of quartz particles in the "sugary" crush crushing zone in the strong and weak unloading zone has visco-slip stress trace. The dislocation of the "Sugar" crush fracture zone mainly occurred in the Middle Pleistocene to the late Pleistocene. (4) the alteration in the dam site is multistage, and the alteration products are formed at different stages and the temperature varies greatly. The dynamic fluid in contact with the surrounding rock is the oxidized fluid rich in magnesium and iron; The rock is rich in aluminum and alkali in the "sugary" crushing zone, which is related to the decomposition of plagioclase and the formation of new minerals such as light-colored mica. The variation of the principal elements in the same adit shows that the fault structure has obvious control over the redistribution of the principal elements. (5) combined with the superposition of the alteration, according to the alteration temperature, the width of the broken zone and the color of the material in the broken zone, In the weathering state and the effect of groundwater, the "sugary" crush fracture zone is divided into slight alteration type, moderate alteration type and strong alteration type. Different alteration types are composed of different combinations of high-temperature and low-temperature dynamic structural alteration and secondary weathering alteration. (6) the specific lithology of the dam site. Geological structure and rock mass structure conditions provide material and structural basis for the formation of "sugary" crush fracture zone. The rapid downcutting of the valley results in the strong release of high strain energy in the slope rock mass, and the unloading and rebound of the slope rock mass towards the sky, forming a "sugary" crush crushing zone and producing structural dynamic alteration. The temperature of the dynamic heat flux in contact with the surrounding rock changes from high to low, resulting in slight and moderate alteration. Local weathering intensifies during the late stage of groundwater transformation, and secondary weathering alteration is formed when the zone is superimposed.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV221.2
本文編號：2393149
[Abstract]:Under the influence of regional tectonics, the compressional fracture zone, which is widely developed in the Sanjiang tectonic belt between Eurasian plate and Indian plate, has become the main engineering geological problem restricting the construction and operation of large hydropower stations in China. The basic characteristics, types and causes of the "sucrose" crush fracture zone in the dam site of Yipatan Hydropower Station on the Jinsha River are studied in depth, which lays a foundation for further evaluation of the quality and availability of the rock mass in the "Sugar" crush fracture zone. Based on field investigation, scanning electron microscope (SEM), X) ray powder diffraction (XRD) and geochemical measurement, the macroscopic geological characteristics and altered mineral petrological characteristics of the "Sugar" crush fracture zone are revealed, and the alteration types are classified. The controlling factors and evolution process of sugary crush zone are discussed. The results show that: (1) the "sugary" crushing zone is located in the range of 2790 ~ 2850 m, and the rule of variation with elevation is not obvious; On the left bank, the "Sugar" crush fracture zone has a wide distribution range and a large number. On the right bank, the "Sugar shaped" crush crushing zone is concentrated in the conventional weathering and unloading zone, and the special geological phenomena are seldom revealed in the micro-new rock mass. The horizontal and vertical distribution range is smaller than the left bank; The depth of development of "Sugar" crush fracture zone has the law of deepening with cutting depth and slope turning degree. (2) most of "Sugar" crush fracture zone inherits early structural joints, and its mechanical properties are shearing; The "sugary" crushing zone is weak permeable in general, and will be enhanced in local structure or fissured dense zone. The permeability of medium elevation is usually higher than that of low elevation, and the permeability decreases gradually with the increase of buried depth. (3) observing the morphology characteristics of quartz, we can find that the structure of quartz is shell-like in the "sugary" crush crushing zone of dam site area. There are 5 types of secondary shell, orange peel, moss and insect moths; The dissolution time of quartz particles on the left bank and the complexity of the dissolution structure are positively correlated with the elevation, and the surface of quartz particles in the "sugary" crush crushing zone in the strong and weak unloading zone has visco-slip stress trace. The dislocation of the "Sugar" crush fracture zone mainly occurred in the Middle Pleistocene to the late Pleistocene. (4) the alteration in the dam site is multistage, and the alteration products are formed at different stages and the temperature varies greatly. The dynamic fluid in contact with the surrounding rock is the oxidized fluid rich in magnesium and iron; The rock is rich in aluminum and alkali in the "sugary" crushing zone, which is related to the decomposition of plagioclase and the formation of new minerals such as light-colored mica. The variation of the principal elements in the same adit shows that the fault structure has obvious control over the redistribution of the principal elements. (5) combined with the superposition of the alteration, according to the alteration temperature, the width of the broken zone and the color of the material in the broken zone, In the weathering state and the effect of groundwater, the "sugary" crush fracture zone is divided into slight alteration type, moderate alteration type and strong alteration type. Different alteration types are composed of different combinations of high-temperature and low-temperature dynamic structural alteration and secondary weathering alteration. (6) the specific lithology of the dam site. Geological structure and rock mass structure conditions provide material and structural basis for the formation of "sugary" crush fracture zone. The rapid downcutting of the valley results in the strong release of high strain energy in the slope rock mass, and the unloading and rebound of the slope rock mass towards the sky, forming a "sugary" crush crushing zone and producing structural dynamic alteration. The temperature of the dynamic heat flux in contact with the surrounding rock changes from high to low, resulting in slight and moderate alteration. Local weathering intensifies during the late stage of groundwater transformation, and secondary weathering alteration is formed when the zone is superimposed.
【學(xué)位授予單位】：成都理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TV221.2
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