發(fā)布時間：2018-03-06 18:54

  本文選題：邊坡工程　切入點：非飽和土　出處：《長沙理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：我國南方地區(qū)尤其是西南地區(qū)由于受到地形以及自然環(huán)境的限制,在公路建設上尤其在路基建設方面存在很多先天不足,如:(1)地形復雜導致公路修筑經常出現高填方路基和高挖方邊坡,且其施工周期長,邊坡安全性不高,容易出現因降雨造成水損破壞。(2)南方地區(qū)有明顯的雨季,尤其在西南地區(qū)降雨量分配嚴重不均勻,經常出現晴雨交替、晝晴夜雨等狀況,使得路基表面的溫度與其內部的溫度出現較大的差值,容易出現因溫度造成的路基路面破壞情況。(3)由于設計理念與現行規(guī)范的因素,導致防排水措施在長效性方面欠考慮,容易因為積水導致水分擴散遷移。土體中引起水分擴散遷移的動力是來自各方面的因素組成的,如基質勢、壓力勢、重力勢、溫度勢以及溶質勢等,水分擴散遷移動力的多樣性及其遷移路徑的隨機性,直接導致土體中水分動態(tài)變化呈現多樣性。根據現有理論研究認為路基土的中水分在溫度場的作用下一般以液態(tài)—氣態(tài)—液態(tài)的模式在路基土內部擴散遷移的,這種擴散遷移受到土質、壓實度、溫度、時間以及降雨量的影響,基于上述情況,結合我國南方地區(qū)路基施工的實際情況,設計三組試驗方案進行試驗研究。方案一采用恒溫水浴鍋以及隔水保溫材料建立一個相對恒溫、恒濕的試驗環(huán)境,觀測土樣在底部有恒溫水源的情況下其水分擴散遷移變化情況,并進一步探討不同含水率、不同壓實度以及不同溫度下路基土中水分在豎直向水分擴散遷移的規(guī)律。方案二采用輻射加熱裝置和模擬降雨裝置,分別模擬長時間降雨和干濕循環(huán)下路基土水分遷移擴散,根據測量數據探討不同壓實度的路基邊坡分別受到長時間降雨和干濕循環(huán)作用下路基土中水分在水平向水分擴散遷移的規(guī)律。方案三采用輻射加熱裝置和模擬降雨裝置,觀測壓實度為96%的路基邊坡在不同干濕循環(huán)歷時下路基土中水分在水平向水分擴散遷移,借助三軸試驗儀器,探討高壓實度路基土在不同干濕循環(huán)歷時下土體強度變化規(guī)律。最終試驗結果表明,影響路基土含水率變化的主要原因,可能非來自路基垂直方向的水分擴散遷移,而與路基兩側受到干濕循環(huán)以及非飽和路基土基質勢導致的水分擴散遷移有關。
[Abstract]:Due to the limitation of terrain and natural environment, there are many natural defects in highway construction, especially in subgrade construction in the south of China, especially in the southwest. For example, the complex terrain often results in high fill subgrade and high excavated slope in highway construction, and its construction cycle is long, the slope is not safe, and it is easy to cause water loss damage due to rainfall. 2) there is an obvious rainy season in southern China. Especially in the southwest region, the distribution of rainfall is seriously uneven, and there are often alternate sunny and rainy days and nights, which make the temperature on the surface of the roadbed differ greatly from the temperature inside the roadbed. Because of the factors of design idea and current code, the water prevention and drainage measures are not considered in the long-term effect. It is easy to cause water diffusion and migration because of water accumulation. The power of water diffusion and migration in soil is composed of various factors, such as matrix potential, pressure potential, gravity potential, temperature potential and solute potential, etc. The diversity of water diffusion and migration dynamics and the randomness of their migration paths, According to the existing theoretical studies, it is considered that the moisture in the subgrade soil is diffused in the subgrade soil under the action of temperature field and the model of liquid-gas-liquid is diffused in the subgrade soil. This diffusion migration is affected by soil quality, compactness, temperature, time and rainfall. Based on the above situation, combined with the actual conditions of roadbed construction in southern China, Three groups of test schemes were designed to carry out the experimental research. The first scheme was to establish a relatively constant temperature and humidity test environment by using a constant temperature water bath pot and water insulation material. Observing the change of water diffusion and migration of soil sample under the condition of constant temperature water source at the bottom, and further discussing the different moisture content, Under different compaction degree and different temperature, the law of water diffusion and migration in vertical direction in subgrade soil. Scheme two uses radiation heating device and simulated rainfall device to simulate water migration and diffusion of subgrade soil under long rainfall and dry and wet cycle respectively. Based on the measured data, the regularity of horizontal water diffusion in subgrade slope subjected to long rainfall and dry and wet cycles respectively is discussed. Scheme 3 uses radiation heating device and simulated rainfall device. Under different dry-wet cycle duration, the moisture in roadbed slope with compactness of 96% is observed to diffuse horizontally to water, and the triaxial test instrument is used. The change law of soil strength under different dry-wet cycle duration of high-pressure subgrade soil is discussed. The final test results show that the main reason that affects the change of soil moisture content may not come from the water diffusion migration in vertical direction of roadbed. But it is related to the moisture diffusion and migration caused by dry and wet circulation and unsaturated subgrade soil matrix potential on both sides of roadbed.
【學位授予單位】：長沙理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U416.1

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