發(fā)布時間：2018-04-26 23:34

  本文選題：黃土 + 崩塌�。� 參考：《蘭州大學》2017年碩士論文

【摘要】：崩塌是我國中西部常見的地質災害之一。黃土崩塌主要分布于黃土高原地區(qū),由于其單體規(guī)模相對較小,其危害往往被人們所忽視,但黃土崩塌在黃土高原地區(qū)廣泛發(fā)育,且對黃土斜坡的穩(wěn)定和演化有著不可忽略的作用。為此,本文以平涼市區(qū)涇河北岸為研究區(qū),研究該區(qū)域崩塌災害的分布發(fā)育特征及演化過程,并對拉裂-墜落式崩塌臨界破壞條件加以研究。首先,通過調查平涼市區(qū)涇河北岸崩塌災害,根據其物質組成和破壞模式對崩塌進行分類。崩塌的分布特征受到了地形地貌和地層巖性的控制,黃土崩塌較規(guī)模相對較小,廣泛分布于調查區(qū)黃土塬邊、沖溝兩側岸坡高陡之處;相較于黃土崩塌,黃土-基巖崩塌規(guī)模相對較大,分布在調查區(qū)沖溝溝口基巖出露的地方。其次,對崩塌的影響因素進行分析。崩塌的影響因素主要有:地形地貌、地層巖性、結構面、水的作用、風化作用、人類工程活動、根劈作用及楔劈作用。分析各個影響因素對崩塌的影響,并對崩塌的演化過程進行研究。最后,對拉裂-墜落式崩塌的臨界破壞條件進行研究。黃土-基巖崩塌的破壞模式為拉裂-墜落式破壞,是由于底部泥巖遭受風化剝蝕形成空腔,空腔上部形成懸臂,隨著底部泥巖進一步風化剝蝕,懸臂長度不斷增加,當懸臂增加到一定長度時,基巖和上覆物質的重力在懸臂根部產生的拉應力將大于基巖的抗拉強度,此時基巖就會產生拉裂縫,隨著拉裂縫不斷發(fā)展,最終基巖和黃土將一起產生崩塌破壞。本文根據材料力學和彈塑性力學,歸納其力學模型,推導了懸臂臨界長度的理論計算公式,并對理論公式的計算結果進行分析對比,結合崩塌實例對理論公式進行校驗。
[Abstract]:Collapse is one of the common geological hazards in the Midwest of China. The collapse of loess is mainly distributed in the Loess Plateau area. Because of its relatively small size, its harm is often neglected by people, but the collapse of the loess is widely developed in the Loess Plateau area and has an unnegligible effect on the stability and evolution of the loess slope. The North Bank of the Jinghe River in cold urban area is the research area, studying the distribution development characteristics and evolution process of the collapse disaster in this area, and studying the critical failure conditions of the collapse and falling type collapse. First, by investigating the collapse of the northern shore of the Jinghe River in Pingliang, the collapse is classified according to its material composition and failure mode. The distribution characteristics of the collapse are subjected to the distribution characteristics of the collapse. The landform and formation lithology control, the loess collapse is relatively small, widely distributed in the Loess Tableland of the investigation area, the slope of the gully slope is high and steep, compared with the loess collapse, the Loess bedrock collapse scale is relatively large, distributed in the area of the gully gully base rock in the investigation area. Secondly, the influence factors of the collapse are analyzed. The main factors affecting the collapse are: topography, lithology, structure surface, water effect, weathering, human engineering activities, root splitting and wedge splitting. The impact of various factors on the collapse is analyzed and the evolution process of the collapse is studied. Finally, the critical conditions for the collapse and fall type collapse are studied. The failure mode of rock collapse is cracked and falling, because the bottom mudstone is weathered and denuded to form the cavity, and the cantilever is formed on the upper part of the cavity. With the further weathering and erosion of the bottom mudstone, the length of the cantilever increases continuously. When the cantilever is increased to a certain length, the tensile stress produced by the gravity of bedrock and overlying material at the root of the cantilever will be greater than that of the cantilever. The tensile strength of the bedrock will produce tensile cracks at this time. With the continuous development of the tensile cracks, the bedrock and the loess will eventually produce collapse and destruction together. In this paper, the mechanical model is summed up based on the mechanics of material and elastoplastic mechanics, the theoretical calculation of the critical length of the cantilever is derived, and the calculation results of the theoretical formula are analyzed and compared. The theoretical formula is checked with the case of collapse.

【學位授予單位】：蘭州大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：P642.21

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本文編號：1808204