大围压重载荷高端电液动三轴试验系统的关键技术研究

According to the seismic analysis of the soil for the major and complex geotechnical engineering such as current world-class dam under construction in China and other large infrastructure projects, there is acute lack of testing instrument for large sample, high confining pressure and heavy loadings. In order to resolve this problem, a new and largest triaxial test equipment in the world has been developed by use of electro-hydraulic servo system. Several key scientific and technological problems that brought by high confining pressure and heavy loadings will be solved based on this large-scale hydraulic test equipment in this project such as: (1) Proposing synchronous reverse compensation control scheme, designing synchronous compensation device for the inertia force and improving cross-coupling controller by adding quadratic differential parameter. (2) Analyzing the mechanism impacting on the electro-hydraulic servo loading system that generated by the nonlinear friction factors and using the iterative learning control method to compensate the tracking error that caused by the nonlinear friction factors. (3) Researching on the mechanical decoupling device for the dynamic balance in the confining pressure (water pressure) control and solving the coupling problem that caused by the rod's movement and the specimen volume's changes. (4) Proposing an optimal energy-saving method in the long-static loading process by using minimize power as the objective function and combining the optimal control theory, practical constraints (such as: static loading control accuracy, etc.) and Fibonacci optimization method; Using fuzzy control strategy to realize positive and negative two-way adjusting the AC variable frequency motor and proportional-pressure valve to reduce the influence of the combined mutation pressure in the static and dynamic switching process. The research results will provide advanced test conditions for the complex geotechnical engineering. This project will play a significant role in breaking through the foreign technical blockade and improving the independent intellectual property rights.

针对当前我国在建世界级水坝等特大型基础建设工程抗震分析试验中急缺大试样、高围压、重载荷动三轴试验设备的现状，课题组采用电液伺服系统研制国内外规模最大的动三轴试验系统。本课题以此大型液压试验装备为研究对象，拟解决大围压、重载荷指标带来的关键科学技术问题，主要有：（1）提出惯性力同步反向补偿的控制方案，设计惯性力同步反向补偿装置，改进交叉耦合控制器增加二次微分环节解决同步控制问题。（2）分析摩擦非线性因素对电液伺服加载的影响机理，利用迭代学习控制方法补偿由摩擦非线性引起的加载轨迹误差。（3）自主研制大围压（水压）动平衡机械解耦装置，解决压力室内连杆伸缩和试样体变引起的耦合问题。（4）结合最优控制理论实现长时静态加载的最优节能控制，利用模糊控制正反双向调节变频电机和比例溢流阀减小合流压力突变影响。课题的研究成果将为复杂岩土工程抗震分析提供先进的试验条件，对提高自主知识产权水平具有重要意义。

针对当前我国在建水坝等特大型基础建设工程抗震分析试验中急缺大试样、高围压、重载荷动三轴试验设备的现状，采用电液伺服系统研制了大围压重载荷高端动三轴试验系统，项目结合研制过程中碰到的关键科学技术问题开展研究，主要工作如下：.（1）自主开发了大围压重载荷高端电液动三轴试验的测控系统，解决了设备加工、调试过程中的难点技术问题，为实验室内模拟复杂的载荷提供了先进的条件，实现了1000T拉压载荷的静态加载和正弦波、三角波、随机波等的动态加载。.（2）研制了大行程高精度位移检测装置和大排水量高精度连续检测装置，研究了影响大行程位移和大排水量精确测量的主要因素，实现了大行程位移（>800mm）和大排水量(>160L)的交替式、连续高精度检测。.（3）完成了惯性力补偿控制的研究，建立了大围压重载荷动三轴试验系统的数学模型，找到了惯性力补偿临界点（0.106Hz），提出了同步补偿控制方案实现了惯性力的动态补偿。.（4）采用迭代学习控制方法补偿了摩擦非线性引起的力加载误差，完成了摩擦力补偿实验，实验结果表明：迭代学习控制方法能较明显地改善波形畸变问题。.（5）自主研制了围压动平衡机械解耦装置，解决了压力容器内连杆伸缩和试样体积变化引起的耦合问题。通过仿真和实验验证了不同激振频率下机械解耦装置的有效性，明显地降低了耦合影响。.（6）研究了多泵合流液压能源系统，建立了多泵合流系统的数学模型，探讨了多泵合流压力突变的影响机理，提出了采用模糊PID控制器减少合流压力突变的方案。结合实际工作状况，通过降压调节实现节能控制。.（7）分别采用电液伺服控制系统和AC伺服电机控制系统研制了高围压水压力加载装置，实现了静态和任意复杂加载路径的控制。.（8）利用项目指导了10余名硕士研究生、协助指导了3名博士研究生，在国内外重要期刊、国际会议上发表论文20余篇，其中SCI、EI 检索10余篇。申报了国家发明专利10项，其中已授权6项。