【摘要】：我國(guó)西北廣大地區(qū)被黃土所覆蓋,典型地區(qū)地表千溝萬(wàn)壑。在我國(guó)經(jīng)濟(jì)建設(shè)的大潮中,大量基礎(chǔ)設(shè)施不斷建設(shè),開山修路架橋,修建高樓大廈數(shù)量越來(lái)越多,接踵而來(lái)的是邊坡問題的突出,地災(zāi)隱患點(diǎn)數(shù)目的不斷增加,規(guī)模持續(xù)上升。與此同時(shí)我們不斷采取工程地質(zhì)措施來(lái)防止治理邊坡問題的發(fā)生和發(fā)展。通過(guò)工程經(jīng)驗(yàn)發(fā)現(xiàn),一般斜坡不會(huì)在應(yīng)力不平衡后立即失穩(wěn),而是產(chǎn)生蠕滑變形。斜坡中部分剪切應(yīng)力隨著斜坡變形消散,漸漸趨于穩(wěn)定,另一部分斜坡蠕變之后進(jìn)入加速滑動(dòng)階段產(chǎn)生滑坡。筆者對(duì)時(shí)間積累效應(yīng)因素對(duì)斜坡穩(wěn)定性影響進(jìn)行了仔細(xì)總結(jié),這些因素包括黃土本身所具有的特點(diǎn),也包括降雨、地表徑流、地下水、地震、植被、凍融作用、農(nóng)業(yè)灌溉、修房筑路、礦藏開采等外在因素。時(shí)間累積效應(yīng)主要在這兩方面影響斜坡的穩(wěn)定性。第一、當(dāng)黃土斜坡強(qiáng)度在峰值強(qiáng)度和長(zhǎng)期強(qiáng)度之間,或者由于斜坡所處應(yīng)力場(chǎng)、黃土自身物理力學(xué)性質(zhì)的改變,使黃土強(qiáng)度進(jìn)入到上述強(qiáng)度范圍以內(nèi)時(shí),黃土斜坡產(chǎn)生蠕變。斜坡蠕變可能是衰減蠕變,逐步進(jìn)入穩(wěn)定階段,或者是非衰減蠕變,導(dǎo)致黃土斜坡的失穩(wěn)。第二、隨著時(shí)間的推移,斜坡受到各種因素影響的機(jī)率會(huì)不斷增大。例如斜坡遭遇突發(fā)因素大地震、大洪水的概率增加,使外力高于黃土的峰值強(qiáng)度,使黃土斜坡發(fā)生突發(fā)性破壞。黃土斜坡可能短期內(nèi)處于穩(wěn)定狀態(tài),但是隨著時(shí)間推移,遭遇各種不利因素的影響,會(huì)使斜坡不斷向失穩(wěn)的方向發(fā)展。選定FLAC3D巖土分析軟件進(jìn)行數(shù)值模擬,比較其中各模型的優(yōu)缺點(diǎn),最終選定伯格斯組合模型和摩爾庫(kù)倫模型,來(lái)討論不同坡型、不同力學(xué)性質(zhì)黃土等的時(shí)間積累效應(yīng)穩(wěn)定性,以及蠕變狀態(tài)下,斜坡的變形狀況。
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圖片說(shuō)明：降水滲流討程圖
[Abstract]:The vast areas of northwest China are covered by loess, and the surface of typical areas is thousands of gullies. In the tide of economic construction in our country, a large number of infrastructure facilities continue to be built, open mountains to build roads and bridges, build more and more high-rise buildings, followed by the prominent slope problems, the purpose of hidden dangers of land disasters continues to increase, and the scale continues to rise. At the same time, we continue to take engineering geological measures to prevent the occurrence and development of slope control problems. Through engineering experience, it is found that the general slope does not lose stability immediately after stress imbalance, but produces creep deformation. Part of the shear stress in the slope dissipates with the deformation of the slope and tends to be stable gradually, and the other part of the slope enters the accelerated sliding stage after creep to produce landslides. In this paper, the effects of time accumulation on slope stability are carefully summarized, including the characteristics of loess itself, including rainfall, surface runoff, groundwater, earthquake, vegetation, freeze-thaw, agricultural irrigation, building roads, mining and other external factors such as rainfall, surface runoff, groundwater, earthquake, vegetation, freeze-thaw, agricultural irrigation, building roads, mining and so on. The time accumulation effect mainly affects the stability of slope in these two aspects. First, when the strength of loess slope is between the peak strength and long-term strength, or because of the stress field where the slope is located, the physical and mechanical properties of loess itself change, so that the strength of loess enters the above strength range, the loess slope produces creep. The creep of slope may be attenuated creep, gradually enter the stable stage, or non-attenuated creep, resulting in the instability of loess slope. Second, with the passage of time, the slope will be affected by a variety of factors will continue to increase the probability. For example, when the slope encounters a sudden earthquake, the probability of the flood increases, which makes the external force higher than the peak strength of the loess, and makes the loess slope cause sudden damage. Loess slope may be in a stable state in a short period of time, but with the passage of time, the slope will continue to develop in the direction of instability due to the influence of various adverse factors. FLAC3D geotechnical analysis software is selected for numerical simulation, and the advantages and disadvantages of each model are compared. finally, Boggs combination model and Moor Coulomb model are selected to discuss the stability of time accumulation effect of different slope types and loess with different mechanical properties, as well as the deformation of slope under creep state.
【學(xué)位授予單位】：長(zhǎng)安大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P642.22

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