云南红土型大坝的干湿循环效应研究

It is urgent to study the cycle role of wet and dry especially extremely dry climate on the deterioration problems of Yunnan lateritic dam and that is the aim of this research. Against cracking, deformaton，leakage，instability of Yunnan lateritic dam general existence, consider reservoir water and rainfall and dry caused cycle roles of wet and dry, water-dam laterite-humidifiers-dewetting-wet and dry cycles-deterioration as a research system, by means of theoretical analysis, model test, macro and micro test, numerical analysis and image processing, research macro and micro characteristics and water-soil interaction characteristics and instability of the dam laterite in humidifiers dewetting, wet and dry cycles processes, and relationshop of erosion, migration, damage, instability between water and dam laterite. Based on the deterioration of water on lateritic dam, damage of water on laterite micro structure, water-soil interaction, combine model test results and macro and micro response and water-soil interaction and instability of the dam laterite in humidifiers, dewetting, wet and dry cycles processes, the macro and micro deterioration characteristics and water-soil interaction characteristics and instability will be explored, deterioyation mechanism of the lateritic dam will be revealed out, in the cycle role of wet and dry. It is very important of this research for effective guidance prevention and cure of the plant disease of Yunnan lateritic dam.

干湿循环特别是极端干旱气候引起云南红土型大坝的劣化是红土工程中丞待解决的现实问题。项目针对云南红土型大坝普遍存在的开裂、变形、渗透、失稳等病害，考虑库水、降雨、干旱引起的干湿循环，将“水-大坝红土-增湿-脱湿-干湿循环-劣化”作为研究系统，采用理论分析、模型试验、宏微观试验与数值分析和图像处理相结合的方法，研究大坝红土在增湿、脱湿、干湿循环过程中的宏微观特性及对应的水-土作用特性和失稳特性，研究水与大坝红土间的侵蚀、迁移、损伤、失稳关系。以红土型大坝的劣化为基础，以水对红土微结构的损伤为出发点，以水-土相互作用为核心，以模型试验结果、宏微观特性和失稳特性为依据，将大坝红土在增湿、脱湿及干湿循环过程中的宏微观响应与其水-土作用和失稳关系结合起来，阐明干湿循环下大坝红土的宏微观劣化特征、水-土作用特征和失稳特征，揭示干湿循环下红土型大坝的劣化机理。对于有效指导云南红土型大坝病害的防治意义重大。

干湿循环特别是极端干旱气候引起云南红土型大坝的劣化是红土工程中丞待解决的现实问题。本项目针对云南红土型大坝普遍存在的开裂、变形、渗透、失稳等病害，以增湿、脱湿引起的干湿循环作为控制条件，以水-土相互作用为核心，将水-大坝红土-增湿-脱湿-干湿循环-劣化作为研究系统，采用理论分析、模型试验、宏微观试验与图像处理相结合的方法，开展了云南红土型大坝的室内模型试验，明确了库水位升降的干湿循环作用下大坝红土的宏微观劣化特性。针对干密度、含水率、循环次数、循环幅度、温度、时间、方向、深度、粒径、固结压力、含砂率、排水条件、试样尺寸、硝酸比例等不同影响因素的研究，明确了干湿循环红土在不固结不排水和固结不排水条件下的宏微观剪切特性；明确了干湿循环红土的水分迁移特性和渗透特性，建立了单层红土、分层红土的水分迁移模型，提出了云南红土的水分迁移经验公式，阐明了渗蚀作用；明确了脱湿过程、增湿过程、干湿循环过程中红土土-水特性的变化，建立了土-水特性拟合模型，阐明了土-水作用；明确了干湿循环红土的竖向、横向以及体积等宏微观胀缩特性，阐明了循环胀缩机理；明确了干湿循环红土的裂缝发展特性，阐明了裂缝发展过程；明确了酸雨对干湿循环红土的宏微观蚀变特性，阐明了酸蚀作用。较系统地揭示了不同影响因素对干湿循环红土劣化特性的影响规律，奠定了深入揭示干湿循环作用引起红土型工程产生劣化机理的基础，为实际红土型工程有效防治长期干湿循环作用产生的劣化效应提供技术参数。