乾安泥林土的工程地质特性对泥林潜蚀作用影响机制研究

Sub-erosion landform with complex mechanism in the national geological park of the QianAn mud forest in Jilin province is widely developing. The national geological park of the QianAn mud forest is the only sub-erosion geology landform group protected by the state with highly ornamental and research value at present. The QianAn mud forest which experiences serious soil loss is a dynamic existing and evolving ecological environment fragile area. The decrease of sub-erosion landscape and vertical scatted collapse disaster which caused by soil erosion have become prominent and important issues to be solved in the national geological park. The study of mud forest sub-erosion mechanism is the key to solve the above problems. . This project intends to start sub-erosion mechanism study from the engineering geology properties of the mud forest soil. First, soil formation, distribution of joint and crack will be investigated and their relationship with sub-erosion landform will be analyzed. Then, soil physico-chemical material properties and microstructure characteristic will be checked by laboratory test. While in view of two sub-erosion types，permeating sub-erosion test will be designed and carried out to study soil physical and chemical mechanism and its rate, and disintegration test will be carried out to study the disintegrating behavior and its rate. Based on the above study, sub-erosion mechanism and main controlling factor in view of engineering geological properties of mud forest soil will be revealed, which will provide scientific evidence for evaluation of sub-erosion development degree and the mitigation of soil loss and vertical scattered collapse.

吉林乾安泥林国家地质公园潜蚀地貌发育，形成机制复杂，是目前受国家保护的唯一的“泥林”潜蚀地质地貌群，是极具观赏和研究价值的地质遗迹。泥林又是动态存在并不断演化的生态环境脆弱区，水土流失带来的景观减少和潜蚀错落崩塌灾害已成为泥林地质公园突出且亟待解决的重要问题，而对泥林潜蚀作用机理的研究是解决以上问题的关键。.本项目拟从泥林土特殊的工程地质性质入手，现场调查土的成因、节理裂隙分布特征，分析其与潜蚀地貌的关系；基于泥林土的物化组成、微观结构，分析潜蚀作用的岩土本质；针对两种常见潜蚀方式，开展潜蚀水理性质试验，设计渗透潜蚀试验研究泥林土物理、化学潜蚀作用机理、渗透潜蚀激发条件和潜蚀速率；设计泥林土湿化崩解水理特性试验，研究泥林土崩解机理及崩解速率。通过以上研究，揭示泥林土特殊的工程地质性质对泥林潜蚀作用影响机制及主控因素，为评价泥林潜蚀发育程度、减缓水土流失及潜蚀错落崩塌防治提供科学依据。

吉林乾安泥林国家地质公园潜蚀地貌发育，形成机制复杂，是目前受国家保护的唯一的“泥林”潜蚀地质地貌群。水土流失带来的景观减少和潜蚀错落崩塌灾害已成为泥林地质公园突出且亟待解决的重要问题，而对泥林潜蚀作用机理的研究是解决以上问题的关键。. 本项目以吉林省乾安泥林为研究对象，通过现场调查、室内试验、理论分析等手段，从泥林土特殊的物化组成、结构特征、水理性质出发，深入剖析泥林土物理潜蚀和化学潜蚀作用机理。获得主要结论如下：.（1）明确了泥林潜蚀地貌类型、错落崩塌等土体破坏形式及演化阶段。泥林形成机理主要为局部抬升和较低湖泊水位导致的较大的水头差；泥林区地下水丰富，为地下潜蚀提供了富水环境；地下水受蒸发浓缩型控制，在循环过程中为土壤提供了丰富的可溶性盐，促进了地下潜蚀的发生。.（2）基于泥林土的物化成分及微观结构，揭示了泥林土物理、化学潜蚀作用机理。泥林黄土状亚砂土以粉粒为主，孔隙率较高，可溶盐含量较多，尤其是Na离子含量高，泥林土遇水极易崩解，自然干燥泥林土，胶结连接和强结合水连接占主导地位，遇水形成较厚的水膜，使土壤颗粒极易分散，这是泥林地区地下潜蚀的根本原因。.（3）自制低渗透压力渗透潜蚀实验，获得低渗透压力下泥林土渗透潜蚀激发条件、潜蚀速率及影响因素。分析了水力梯度、流速、流量和潜蚀速率与密实度影响关系。潜蚀流速随水力梯度的增加而增大，呈线性关系，潜蚀破坏的临界水力梯度在0.5左右。.（4）自制崩解实验仪，获得了不同埋深、不同含水量的泥林土湿化崩解机理、崩解速率及影响因素。土体中易溶盐含量较高遇水后，随着易溶盐的溶解，颗粒之间的粘结力不断减弱，土体内部出现了新的裂隙以及原来存在的裂隙扩张，较高的孔隙率导致土体更容易逸出气泡。. 通过以上研究，揭示了泥林土特殊的工程地质性质对泥林潜蚀作用影响机制及主控因素，为评价泥林潜蚀发育程度、减缓水土流失及潜蚀错落崩塌防治提供科学依据。