复杂地质条件下混凝土防渗墙裂缝渗流特性试验及模型研究

Concrete anti-seepage wall plays an important role in seepage control of complicated foundation such as deep overburden. However, there are various through cracks of the concrete wall appeared in the process of construction and operation periods. With the groundwater flow, the cracks are then filled by the fines in the foundation and the seepage characters change further. There are few research achievements on the experiments and mathematical models for seepage characters around the anti-seepage wall cracks recently. In order to find out the real crack seepage characters of concrete wall before and after filling, this research will simulate the crack of anti-seepage wall by using split concrete block in large-scale model test. First, various stress conditions and hydraulic gradient are designed while crack aperture and roughness of cracks are changed to research the seepage characters and mathematical model of the cracks without filling. Then, in the basis of the above tests, earth-rock materials with different grain-size are put into the model tests to research the filling mechanism and the related seepage characters and mathematical model of the filling cracks. The numerical simulation methods are also used to research the applicable conditions of these mathematical models. This research aims at revealing the crack seepage characters of the concrete anti-seepage wall in the influence of aperture, roughness, number and grain-size of overburden considering hydro-mechanical (HM) coupling effect, clearing the filling mechanism of cracks of the wall. These results can be used for further analysis on seepage instability of deep overburden foundation and selection of the related engineering reinforcement measures.

混凝土防渗墙对于深厚覆盖层地基中的渗流控制十分重要，但是在其施工和运行过程中极易产生各种贯穿性的裂缝，这些裂缝会逐渐被地基中的细粒料充填，改变了地基的渗流性态。国内外目前鲜有防渗墙裂缝渗流试验方面的研究，为了弄清复杂地质条件下防渗墙裂缝充填前后的渗流特性，本项目拟在室内大型模型槽内采用劈裂的混凝土块模拟防渗墙裂缝，设计不同的应力条件和水力比降，改变裂缝的开度和粗糙度，研究防渗墙裂缝未充填时的渗流特性和数学模型；在此基础上，在模型槽内添加不同级配的覆盖层土石料，进一步研究防渗墙裂缝的充填条件及充填后的渗流特性和数学分析模型；并结合工程实际，采用数值仿真技术研究裂缝渗流数学模型的适用条件。本研究旨在揭示水-力耦合作用下复杂地质条件中防渗墙在裂缝开度、粗糙度、裂缝条数以及土石料充填等因素影响下的渗流规律，为进一步研究深厚覆盖层地基的渗透失稳机制、选择工程加固措施奠定基础。

混凝土防渗墙对于深厚覆盖层地基中的渗流控制十分重要，但是在其施工和运行过程中极易产生各种贯穿性的裂缝，这些裂缝会逐渐被地基中的细粒料充填，改变了地基的渗流性态。国内外目前鲜有防渗墙裂缝渗流试验方面的研究，为了弄清复杂地质条件下防渗墙裂缝充填前后的渗流特性，本项目通过研发了室内大型水-力耦合渗流试验仪，并在室内大型模型槽内采用劈裂的混凝土块模拟防渗墙裂缝，设计了不同的应力条件和水力比降，改变裂缝的开度和粗糙度，研究了防渗墙裂缝未充填时的渗流特性；在此基础上，在模型槽内添加多种不同级配的覆盖层土石料，进一步研究了防渗墙裂缝的充填条件及充填后的渗流特性和数学分析模型；并结合工程实际，采用数值仿真技术研究裂缝渗流数学模型下典型土石坝地基渗流特性，研究成果为进一步研究深厚覆盖层地基的渗透失稳机制、选择工程加固措施奠定基础。