本文關(guān)鍵詞：寧夏海原縣地質(zhì)災(zāi)害發(fā)育特征及形成機理研究　出處：《中國地質(zhì)大學(xué)(北京)》2015年碩士論文　論文類型：學(xué)位論文

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【摘要】：海原縣位于寧夏回族自治區(qū)南部地區(qū),地層區(qū)劃大部屬秦祁昆地層區(qū),地貌以黃土丘陵為主。黃土丘陵的形成,主要是由流水切割上覆于古近系-新近系基巖之上的第四紀(jì)黃土,再經(jīng)過土壤侵蝕等內(nèi)、外地質(zhì)作用,最終形成溝壑縱橫,黃土殘塬、梁峁齊備的地貌特征。山地是由地殼擠壓變形,在褶皺、斷裂等構(gòu)造作用下隆升,后期經(jīng)風(fēng)化、剝蝕等外動力地質(zhì)作用改造而成,所以海原縣的地形整體起伏較大。在地質(zhì)構(gòu)造運動的作用下,海原縣經(jīng)過清水河、祖歷河及其支流的侵蝕切割,形成了現(xiàn)今溝谷眾多、梁峁起伏、地面破碎的地貌景觀。由于海原縣的這種獨特地理環(huán)境,使之成為地質(zhì)災(zāi)害的高發(fā)區(qū)和易發(fā)區(qū)。本論文通過對崩滑流以及不穩(wěn)定斜坡等地質(zhì)災(zāi)害的分布特點、發(fā)育特征和形成機理的綜合研究,取得了如下進展:一、海原縣境內(nèi)地表水系發(fā)育,溝壑縱橫,地形破碎,地貌類型以黃土高原梁峁為主,地質(zhì)環(huán)境條件十分脆弱,水土流失較嚴重。斷裂構(gòu)造較發(fā)育,發(fā)生過多次破壞性地震�？傮w來看,海原縣屬于地質(zhì)災(zāi)害的高易發(fā)區(qū)。二、海原縣境內(nèi)的地質(zhì)災(zāi)害多集中在主要河流的支流岸邊斜坡上,沿河岸分布;在黃土厚度較大的陰坡集中;在直線型和凸型邊坡地段相對集中。從時間上來看,在地質(zhì)歷史時期,滑坡、崩塌多出現(xiàn)在全新世;在人類歷史時期,滑坡、崩塌多發(fā)生于人類活動頻繁時期;在一年之內(nèi),滑坡、崩塌在7、8、9這三月內(nèi)相對集中發(fā)生;在構(gòu)造活動年,1920年的海原大地震時期地質(zhì)災(zāi)害集中出現(xiàn)。三、滑坡、崩塌和不穩(wěn)定斜坡等地質(zhì)災(zāi)害總體上具有數(shù)量多、分布集中的特征。多數(shù)滑坡平面形態(tài)較完整、厚度不大,如遇降雨易復(fù)活;崩塌總體規(guī)模較小、但危害性大;不穩(wěn)定斜坡坡寬跨度大、坡形以凸形坡和直線型坡為主;潛在崩滑地質(zhì)危害嚴重。四、導(dǎo)致滑坡崩塌等自然災(zāi)害形成的控制因素包括坡體地質(zhì)結(jié)構(gòu)、坡體形態(tài)、地層巖性等;影響因素包括地下水和降雨;主要觸發(fā)因素是地震,其次是人類工程活動和降雨的雙重作用。對滑坡崩塌災(zāi)害發(fā)生的頻度和產(chǎn)生風(fēng)險具有明顯的控制作用的因素還包括黃土的厚度、強度及其下伏新近系泥巖的出露高度,這些因素也決定了斜坡變形破壞的方式和強度。大氣降水改變了巖土體的抗剪強度、孔隙水壓力、容重和浮托力,創(chuàng)造了崩滑形成的條件;地表水以水流的形式侵蝕巖土體,創(chuàng)造崩滑活動的臨空條件;由于地下水活動的潤滑作用和軟化作用,導(dǎo)致黃土強度降低、改變了坡體應(yīng)力狀態(tài),進而加速了巖土體的變形破壞。地震是地災(zāi)的主要誘發(fā)因素,降雨造成老滑坡復(fù)活,人類不合理工程活動會加劇斜坡形成崩滑地質(zhì)災(zāi)害的危害。
[Abstract]:Haiyuan County is located in the southern region of Ningxia Hui Autonomous region, the stratigraphic division is the Qinqi-Kun stratigraphic area, the landform is mainly loess hilly, loess hilly formation. The Quaternary loess was cut by income, which was overlying the Paleogene and Neogene bedrock, and finally formed gully vertical and horizontal, loess remnant tableland after soil erosion and other internal and external geological processes. The mountainous area is formed by the crustal compression deformation, uplift under the action of fold, fault and so on, after weathering, denudation and other external dynamic geological processes. Under the action of geological tectonic movement, Haiyuan County has been cut by the erosion of Qingshui River, Zuli River and its tributaries, forming a large number of gullies and ridges, ridges and knolls. Because of the unique geographical environment of Haiyuan County, it has become a high incidence area and a prone area for geological disasters. This paper analyzes the distribution characteristics of geological hazards such as landslides and unstable slopes. The development characteristics and formation mechanism of the comprehensive research has made the following progress: first, Haiyuan County surface water system development, gully vertical and horizontal, topographical fragmentation, landform type mainly in the Loess Plateau hilly. The geological environment condition is very fragile, the soil erosion is serious, the fault structure is relatively developed, and many destructive earthquakes have occurred. Generally speaking, Haiyuan County belongs to the high risk area of geological hazards. The geological hazards in Haiyuan County are mostly concentrated on the bank slopes of the main tributaries and distributed along the river banks. It is concentrated in the thick slope of loess. From the point of view of time, in the geological history period, landslides and collapses mostly occurred in Holocene. In the period of human history, landslides and collapses mostly occurred in the period of frequent human activities. Within a year, landslides and collapses were relatively concentrated in March; In the year of tectonic activity, geological hazards occurred mainly during the Haiyuan earthquake in 1920. Third, there are many geological hazards such as landslides, landslides, collapses and unstable slopes as a whole. Most landslide plane form is relatively complete, the thickness is not big, if the rainfall is easy to revive; The overall scale of the collapse is small, but the harm is great; The wide span of unstable slope is large, and the slope shape is mainly convex slope and linear slope. The potential landslide geological hazards are serious. Fourthly, the controlling factors of natural disasters such as landslide collapse include slope geological structure, slope body morphology, stratigraphic lithology, etc. Influencing factors include groundwater and rainfall; The main trigger factor is earthquake, followed by the dual effects of human engineering activities and rainfall. The factors that have significant control over the frequency and risk of landslide collapse disaster include the thickness of loess. The strength and the exposed height of the underlying Neogene mudstone also determine the mode and strength of slope deformation and failure. The precipitation changes the shear strength, pore water pressure, bulk density and floating support of rock and soil. Created the conditions for collapse and slip formation; The surface water erodes the rock and soil mass in the form of water flow and creates the condition of collapse and slip. Because of the lubrication and softening of groundwater activity, the strength of loess decreases, the stress state of slope body is changed, and the deformation and failure of rock and soil are accelerated. Earthquake is the main inducing factor of ground disaster. The old landslide is revived by rainfall, and human unreasonable engineering activities will aggravate the hazards of landslide geological hazard.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P694

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