【作者】 邵明申；

【导师】 李最雄；

【作者基本信息】 兰州大学 ， 地质工程， 2010， 博士

【摘要】 土遗址的防风化加固是岩土工程界普遍关注的热点问题。高模数硅酸钾溶液(简称PS)以其良好的加固效果在西北地区土遗址的加固工程中得到广泛应用。但也面临一些关键技术问题,例如PS的入渗特性,PS加固后遗址土的渗透性,以及PS的加固效果等,这些问题的解决有利于扩大推广PS加固土遗址的应用,特别是提高PS加固土遗址的效果。本论文以新疆高昌故城夯土为研究对象,通过现场试验和室内研究相结合的手段,运用非饱和土的理论和技术方法,较为系统的研究这三个关键技术问题。主要内容包括以下三个部分：(1)在交河故城施工现场人工夯筑两段试验墙,模拟遗址中需要加固的夯土部位,通过Ps的入渗试验,研究了PS在现场开放条件下的入渗特性,结果证实低浓度PS(3%-7%)具有和水相近的入渗规律和渗透速度。同时进行的非饱和状态下的渗透试验表明,在土样含水率为9%时PS的入渗性能最佳,含水率达到15%时仍具有较好的渗透性；在持续饱水的状态下,PS加固样仍具有更大的抗剪强度,表现出良好的水稳定性。(2)利用压力膜仪测试了PS加固土的土-水特征曲线,同未加固土相比,饱和含水率θs和残余含水率θr下降,曲线斜率和进气值增大。结合PS与土颗粒的反应机理以及相关试验对此进行了分析,认为矿物成分、孔隙结构、土体的收缩性等因素是导致土-水特征曲线变化的主要原因。在室内进行了封闭条件下的PS入渗试验以及加固土的渗透性试验,利用SWCC和Mualem-Van Genuchten模型推导出非饱和土的相对渗透系数,结果表明PS加固对非饱和土的渗透性能产生了有利的影响,渗透性大幅提高。粒度分析、X射线衍射分析、扫描电镜测试等表明,粘土颗粒加固前为层状、片状的结构,各颗粒之间相互分离,颗粒多有明显的棱角,加固以后,几何形状发生变化,片状结构变为致密的网状结构,颗粒粒径增大,大量棱角弱化或消失,孔隙表面粗糙度随之降低,有效孔隙相对增大,这些变化大幅提高了土体的渗透性。(3)模拟现场的环境变化及特殊的环境条件,对Ps加固和未加固试样进行水稳定性测试、耐风蚀的风洞试验、冻融循环破坏、温度循环破坏及湿度循环破坏等相关试验,以评价Ps加固后的土遗址耐环境诸因素影响的性能。结果证明,经PS加固以后试样抗环境影响的能力数倍甚至十几倍的提高,也说明用PS加固丝绸之路沿线地区的土遗址是切实可行的,可以有效的抵御环境因素的不利影响,起到抢险加固的效果。更多还原

【Abstract】 Recently, the anti-weathering consolidation of the earthen sites has been (a serious concern in geotechnical engineering. Potassium Silicate with modulus 3.8-4.0(PS) is widely utilized in consolidation projects of the earthen sites in northwest of China due to its favorable effect. However, some key technologies, such as infiltration properties of PS, permeability characteristics of unsaturated soil reinforced by PS and the effect of PS consolidation for the earthen sites, must be solved, which is important in popularizing the utilization of PS and increasing the effect of PS consolidation for the earthen sites.In this paper, through the combination of field tests and laboratory studies, the three key technologies mentioned above were systematically investigated with the soil obtained from the ancient ruins of Gaochang based on the theory and techniques of unsaturated soil. Three research contents are as follows:(1) The characteristics of PS infiltration were subjected to fundamental studies in the open environment under the similar soil condition with the earthen site of the ancient city of Jiaohe, the results of which indicated that low PS concentration (3%-7%) was similar with water in infiltration disciplinarian and infiltration velocity. And the infiltration experiments under unsaturated condition suggested that the permeability of PS was optimal when the water content of soil was 9%, and permeability of PS was very well until the water content was 15%. The soil sample reinforced by PS expressed higher shear strength than that without PS, and also expressed good water stability.(2) The soil-water characteristic curves (SWCC) of unsaturated soil reinforced with PS were studied by using pressure plate apparatus. It can be found seen from the curves that the saturated water content (θs) and residual water content (θr) decreased while the air entry value and the slope of the SWCC increased. It can be concluded that the main influencing factors of SWCC were mineral components, pore structure and shrinkage according to the reaction theory between PS and soil particles.The permeability experiments of PS were carried on in the lab and the coefficient of permeability of unsaturated clay was obtained according to SWCC and Mualem-Van Genuchten model. The results showed PS consolidation was advantageous to the permeability of the unsaturated clay and the permeability coefficient increased to some extent. The results of particle size analysis and XRD, SEM tests demonstrated that the original structures of clay, including laminated structure, the separation of particles, more edges and corners, changed to compact net structures, bigger particles, less edges and corners, lower degree of roughness and bending factor, higher effective porosity after consolidated by PS, which increased the permeability of soil samples.(3) Many tests including the disintegration test in water, simulation test of wind erosion and rain erosion, temperature fluctuation test, humidity variation test and freeze-thaw test were carried out, and these experimental results were conducted to evaluate the anti-environmental factors under simulation environment of real field environment variation and condition. The results indicated that the anti-environmental stability of soil consolidated by PS was several to several or ten times higher than that unconsolidated. It also demonstrated that it was feasible to consolidate the earthen sites with PS, which was useful to resist the adverse effect and to increase the consolidation effect of the earthen sites.更多还原