非饱和路基土水分扩散迁移试验研究

发布时间：2018-03-06 18:54

本文选题：边坡工程　切入点：非饱和土　出处：《长沙理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：我国南方地区尤其是西南地区由于受到地形以及自然环境的限制,在公路建设上尤其在路基建设方面存在很多先天不足,如:(1)地形复杂导致公路修筑经常出现高填方路基和高挖方边坡,且其施工周期长,边坡安全性不高,容易出现因降雨造成水损破坏。(2)南方地区有明显的雨季,尤其在西南地区降雨量分配严重不均匀,经常出现晴雨交替、昼晴夜雨等状况,使得路基表面的温度与其内部的温度出现较大的差值,容易出现因温度造成的路基路面破坏情况。(3)由于设计理念与现行规范的因素,导致防排水措施在长效性方面欠考虑,容易因为积水导致水分扩散迁移。土体中引起水分扩散迁移的动力是来自各方面的因素组成的,如基质势、压力势、重力势、温度势以及溶质势等,水分扩散迁移动力的多样性及其迁移路径的随机性,直接导致土体中水分动态变化呈现多样性。根据现有理论研究认为路基土的中水分在温度场的作用下一般以液态—气态—液态的模式在路基土内部扩散迁移的,这种扩散迁移受到土质、压实度、温度、时间以及降雨量的影响,基于上述情况,结合我国南方地区路基施工的实际情况,设计三组试验方案进行试验研究。方案一采用恒温水浴锅以及隔水保温材料建立一个相对恒温、恒湿的试验环境,观测土样在底部有恒温水源的情况下其水分扩散迁移变化情况,并进一步探讨不同含水率、不同压实度以及不同温度下路基土中水分在竖直向水分扩散迁移的规律。方案二采用辐射加热装置和模拟降雨装置,分别模拟长时间降雨和干湿循环下路基土水分迁移扩散,根据测量数据探讨不同压实度的路基边坡分别受到长时间降雨和干湿循环作用下路基土中水分在水平向水分扩散迁移的规律。方案三采用辐射加热装置和模拟降雨装置,观测压实度为96%的路基边坡在不同干湿循环历时下路基土中水分在水平向水分扩散迁移,借助三轴试验仪器,探讨高压实度路基土在不同干湿循环历时下土体强度变化规律。最终试验结果表明,影响路基土含水率变化的主要原因,可能非来自路基垂直方向的水分扩散迁移,而与路基两侧受到干湿循环以及非饱和路基土基质势导致的水分扩散迁移有关。
[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.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U416.1

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