干湿循环作用下红层填料崩解软化机理及其填筑体长期稳定性研究

Under drying and wetting conditions the red beds soft rock tends to slake, the filling material which was made of such kind of rock by crushing may continue slaking after being compacted in embankment under the drying and wetting conditions, leading the embankment’s continuous deformation. The continuous deformation of embankment will lead the progressive cracks appearing on pavements or face-plates sitting on the embankment, and there is still no effective method to treat such cracks. This study will firstly start the research on the scale test methods of the slaking material based on fractal theory and its the scale effects then reveal the engineering properties of the red beds filling material at the same time. Secondly, using the scaled samples the slake mode and its macroscopic and microscopic mechanism as well as the properties of the red beds filling material under different stress conditions and wetting-drying cycles will be studied, to reveal the slaking and soften mechanism and get the evolutionary model of the properties of red beds filling material with the role of drying-wetting cycles. Thirdly, model tests will be conducted on the red beds filling material embankment, using the road embankments as an example, by simulating the wetting-drying conditions due to precipitation and evaporation and testing the responses of the embankment, the seepage and mechanic properties of the embankments under natural condition will be revealed. Finally, based on the research of numerical method on analyzing the coupled fluid-solid effect of unsaturated soil considering the roles of precipitation evaporation variation in water level and soften of filling material, combined the results of model tests, the long term stability of red beds filling materials embankment under natural hydrologic and loading environment will be researched and revealed.

红层软岩在干湿循环作用下容易崩解，由其破碎形成的红层填料埋在填筑体中，在自然干湿循环作用下仍可继续崩解软化，引起填筑体持续变形，导致其上部的道面或面板结构出现渐进式开裂，无法妥善维修。本研究首先基于分形理论提出新的缩尺试验方法，并对崩解性填料的缩尺效应进行研究，同时揭示红层填料的工程性质。然后采用缩尺试件，研究其在不同应力环境、干湿循环条件下的崩解性状和宏/微观机制，探明红层填料崩解软化机理，得到干湿循环作用下红层填料性质演化模型。再后，对红层填料填筑体进行模型试验，模拟现场降雨、蒸发和水位升降等要素构成的自然水文环境形成的干湿循环作用，测试填筑体响应，揭示填筑体在自然干湿循环条件下的崩解、渗流和力学特性。最后，在降雨、蒸发、水位变化、填料软化等多因素耦合作用下非饱和土数值模拟计算方法研究的基础上，结合模型试验，研究并揭示自然水文环境与荷载作用下红层填料填筑体长期稳定性。

红层软岩在干湿循环作用下容易崩解，由其破碎形成的红层填料埋在填筑体中，在自然干湿循环作用下仍可继续崩解软化，可引起填筑体持续变形，导致其上部的道面或面板结构出现渐进式开裂，无法彻底处治，形成的长期病害可造成高额的维修费。现有研究对红层填料的研究缺乏有效理论指导，未能揭示控制红层填料的工程性质和干湿循环作用下的长期工程性质的本质因素，导致工程中对崩解性软岩的处治对策盲目，措施效果欠佳，使得红层地区的道路管理部门单位需承受巨大养护经费和社会舆论压力。.本研究基于分形理论，从岩土材料的成因研究出发，提出了岩土散体材料的颗粒级配分形模型，解决了岩土散体材料的颗粒级配描述方法的障碍；基于对红层填料重复破碎作用机制的模拟，基于分形理论提出红层填料的缩尺试验方法，解决了红层填料研究的缩尺试样制样问题；针对现有崩解试验设备的机械扰动过大，开发了新型的软岩崩解试验仪，解决了易崩解软岩的试验方法问题。在此基础上，通过研究建立了颗粒级配与岩土材料颗粒性质的关系通用模型；采用缩尺试样对填料的崩解性、强度、土水特征特性进行试验，揭示了红层填料的基本力学性质。然后，通过开展浸水崩解和干湿循环下的试样和模型试验，研究红层填料在浸水和干湿循环条件下的崩解性状和宏/微观机制，探明了红层填料崩解软化机理，得到了干湿循环作用下红层填料性质演化规律。基于Matlab平台，开发了计算填筑体边坡稳定性的计算程序，研究了干湿循环作用下，包括凹形填筑边坡在内的填筑体的变形和稳定性演化规律，最后，对红层填料填筑体进行现场观测，验证了理论研究成果的合理性。.本研究揭示了软岩填料崩解软化机理和工程特性，探明了干湿循环作用下红层填料路基稳定性变化规律，成果解决了软质岩填料基础性问题，对崩解性软岩填料的工程应用提供了理论支撑。