【作者】 孙国亮；

【导师】 张丙印；

【作者基本信息】 清华大学 ， 土木工程， 2009， 博士

【摘要】 堆石体的长期变形问题是目前工程界普遍关注又亟待解决的关键问题之一。堆石体的长期变形不仅与外部荷载有关,温度变化、水位波动、雨水入浸和蒸发等环境因素变化都会造成堆石料颗粒的逐步劣化,从而引发堆石体的变形。目前,国内外文献对在应力作用下堆石料风化过程中力学特性变化的研究尚鲜有报道。本文从设备研制入手,通过材料试验、机理分析、模型建立、数值实现和工程应用等多种途径,对应力作用下堆石料风化过程中力学性质变化的规律进行了深入地探讨。本文取得的主要成果有:1.堆石料风化仪研制。研制了可进行干湿循环、温度变化和应力三因素耦合试验研究的堆石料风化仪。该设备包括竖向压缩系统、水平直剪系统、冷热和干湿循环系统。能够研究受荷堆石料在风化过程中的变形和强度特性。2.堆石料风化试验和风化颗粒破碎特性研究。对泥质粉砂岩堆石料分别进行了岩块风化试验以及荷载作用下的干湿循环试验、冷热循环试验和湿冷-干热耦合循环试验。研究了干湿和温度变化导致堆石料发生风化的现象,对比分析了不同环境因素变化对堆石料风化过程和速度的影响,探讨了堆石料在风化过程中的颗粒劣化破碎现象。3.堆石料风化过程中的变形特性研究。根据泥质粉砂岩堆石料风化试验结果,对比分析了干湿、冷热和湿冷-干热耦合循环等不同环境因素变化所致堆石料劣化变形的特点和发生机理。以湿冷-干热耦合循环试验结果为基础,探讨了堆石料劣化变形的发展规律,分别建立了堆石料劣化变形基于初应变方法的非线性模型和弹塑性模型。4.堆石料风化过程中的抗剪强度特性研究。在泥质粉砂岩堆石料湿冷-干热耦合风化试验的基础上,分别进行了风化试验后的就机直剪试验、风化后再剪试验和常规三轴压缩试验,探讨了堆石料风化过程中强度特性的变化规律,分析了堆石料风化过程中抗剪强度变化的颗粒劣化和变形压密双重作用机理。5.有限元计算程序和工程应用。建立了堆石料劣化变形计算模型的有限元格式,并针对糯扎渡高心墙堆石坝上游侧软岩料的使用问题进行了典型工程案例分析。更多还原

【Abstract】 The long-term evolution of rockfill deformation is one of the key issues that draw great attention of engineers and researchers. The long-term deformation of rockfill has relationship with not only loading, but also with environment factors, including wetting-drying cycle, cooling-heating cycle and so on. This thesis aims to investigate the mechanical characteristics of loaded rockfill during weathering. The development of a new test device, experimental observations, physical interpretations, constitutive model, and numerical implementation as well as practical application are presented. The main achievements obtained in the thesis are as follows.1. A new device called weathering test apparatus for rockfill is developed to investigate the deformation and shear strength characteristics of rockfill under the coupling action of drying-wetting cycle, cooling-heating cycle and vertical loading. The apparatus include vertical loading unit, horizontal shearing unit, drying-wetting cycle unit and cooling-heating cycle unit.2. A series of weathering tests including block weathering tests, drying-wetting cycle test, cooling-heating cycle tests and wetting-cooling- drying-heating cycles tests were performed by using argillaceous siltstone rockfill. By analyzing the block weathering phenomena and weathering velocity of argillaceous siltstone rockfill under various environmental factors, the weathering characteristics of particle breakage were investigated.3. Based on the weathering test results on argillaceous siltstone rockfill, the deformation characteristics and mechanism caused by various environmental factors were investigated. On the base of the wetting-cooling-drying-heating cycles tests results, the degrading deformation law was investigated and a nonlinear constitutive model and an elasto-plastic constitutive model were developed to calculate the degrading strain of rockfill.4. Based on the wetting-cooling-drying-heating cycles tests on argillaceous siltstone rockfill, direct shear, re-direct shear and triaxial tests were performed. The shear strength characteristics and mechanism in weathering test were investigated. It was found that the change of the shear strength primarily rest with the actions of rockfill compaction and particle degradation.5. The finite element formulations of the present models were derived and incorporated into the FEM codes. They were applied to the evaluation of practical engineering problems.更多还原