【作者】 张宝文；

【导师】 苏谦；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2013， 硕士

【摘要】 近年来,高速铁路在我国得到了跨越式发展,其长期使用性能值得关注。地基和路基的稳固是高速铁路安全运营的控制性因素,而地基和路基一旦出现性能劣化将直接威胁高速铁路的正常服役。因此,一方面需要开展如何保持高速铁路下部结构安全服役的结构状态和长期性能的研究,另一方面也要加强运营维护技术尤其是病害快速修复技术的研究。目前,注浆加固是地基病害整治的主要手段之一,但是注浆理论研究落后于工程实践,缺少配套的可以直接指导注浆施工的注浆理论和相关技术研究成果。本文通过理论分析、室内模型试验等方法探究了软粘土中注浆浆液的流动扩散规律以及对土体的加固效果,旨在丰富注浆理论,为软粘土地基中注浆加固的实施提供借鉴。得到的主要研究成果如下：(1)建立了扩孔理论计算模型,考虑浆液流变特性和土体特性,初步推导出了注浆中土体的应力应变变化特性以及注浆后土层的加固和抬升规律。首先,将注浆孔周围土体划分为塑性变形区和弹性变形区,推导了各区域的应力场和位移场；其次,在扩孔理论的基础上又考虑了单液水泥浆的流变特性、粘时变特性和粘土的土体特性,应用浆液在土体中的流变理论,从理论上分析了注浆量、注浆压力、浆液水灰比以及土体参数对注浆范围的影响,探究了起劈压力大小的确定方法。最后,将上述的注浆加固理论进一步延伸,探索注浆后地表的抬升理论,利用镜像原理推导注浆抬升量。将上述理论分析结果与注浆试验相结合,得到了粘土中注浆的一些规律性认识,有助于实现预期的注浆效果,指导工程实践,便于推广应用。(2)自行研制了一套室内高压注浆试验系统和装置,设计了完整的软粘土室内模型注浆试验方案。研制成功的试验系统可以通过在模型表面施加不同的竖向柔性荷载来模拟不同深度处的土体,可以实现注浆土体土体和原状土体的分离。利用空气压力和气液转换装置实现压力注浆过程,通过调压阀和压力监测器实现注浆压力的双向控制；在土体中埋设土压力盒和孔隙水压力计来监测注浆过程中土压和水压的变化规律,从而充分探究粘土中的注浆性状。(3)根据室内模型注浆试验结果探究了不同注浆条件下注浆浆液在粘土中的扩散规律,分析了注浆参数对土体加固效果的影响规律。利用试验过程中监测到的注浆时的土压力数据、孔隙水压力数据、注浆量数据、注浆压力数据和试验结束后模型开挖过程中的发现的浆泡、浆脉特征来分析不同注浆条件下浆液在粘土中的扩散规律,得到了注浆压力和浆液水灰比对注浆性状的影响规律。提出了类似土层条件下的“启劈压力”的经验值。通过提取注浆土体和原状土体的土样进行室内常规剪切试验和压缩固结试验,得出了注浆后土体物理力学效能改善的程度以及注浆参数对土体加固效果的影响规律。更多还原

【Abstract】 In recent years, the leaping development of China’s high-speed railway requires us to pay more attention to the railway’s long term performance. The stability of the foundation and subgrade is the controlling factor to guarantee the operation safety of the high-speed railway, however the deteriorated performance of the foundation and subgrade will be a direct threat to the natural service of the high-speed railway. Therefore, on one hand, we need to develop the research about how to maintain the safe structural state and the long-term performance of the high-speed railway substructure. On the other hand, we should strengthen the research about the operation maintenance technology and especially the rapid repair techniques. At present, grouting reinforcement is one of the main methods to regulate the foundation disease, but the theory and research achievements which can be used to guide the grouting construction are deficient and behind the engineering practice. In this paper, the flowing and diffusion law of the grouting slurry and the strengthening effect of the soils are discussed by means of theoretical analysis and indoor model tests and the research results can be used to enrich the theory of grouting and provide reference for the practice of grouting reinforcement in the soft clay foundation.The research achievements are as follows:(1) The calculation model of reaming theory is established while the rheological characteristics of the grouting slurry and the soil characteristics are considered. It can be used to deduce the variation characteristics of stress and strain in the soft soil during grouting and the law of the reinforcing and lifting in the soil layer after grouting.Firstly, the soils around the grouting hole are divided into plastic and elastic areas, the stress field and displacement field of the area are calculated. Secondly, the rheology theory about the grouting slurry creeping in the soil is discussed according to the reaming theory, the rheological and time-varying properties of the single cement slurry and the characteristics of the soil. What’s more, the grouting range are effected by the grouting pressure, grouting capacity, grouting density and the soil parameters is analyzed by related theories.The methods to determine the splitting pressure are explored. Finally, the above mentioned grouting theories are extended to explore the uplifting amount through Principle of Mirror Image. The combination of the above theoretical research and the subsequent experimental study can help to form a series of regular recognition about grouting in the soft clay and predict the grouting effect correctly,which can also be used to provide the guidance to the project practice.(2) A set of device and system which can be used to carry out the grouting experiment under high-pressure environment were self-developed. What’s more, a complete range of experiment project that can be used to guide the laboratory test for grouting in the soft clay was designed.The developed experimental system can simulate different soil depths by applying different confining pressure to the soil, can simulate different consolidation degrees by imposing pre-consolidation load to the surface of the soil, can realize the separation between the soil affected by the grouting slurry and the undisturbed soil. The air pressure and the pneumatic-liquid transfer device can be used to realize the processes of pressure casting, the bilateral control of the grouting pressure can be realized by the pressure regulating valve and the pressure monitoring devices. In order to explore the grouting characteristics, a lot of earth pressure cells and pore pressure gauges were buried in the soil that can be used to monitor the changing law of the earth pressure and the pore water pressure.(3) According to the results of the laboratory model tests,many laws under different grouting parameters were put forward including the law about the diffusion of the grouting slurry in the clay and the law about the soil’s strengthening effects by the grouting slurry.The law about the diffusion of the grouting slurry in the clay and the law about the grouting characteristics affected by the different grouting parameters were analyzed by the pressure test information, the pore water pressure test information, the grout amount test information, the grouting pressure information during grouting and the characteristics of the grouting foams and the grouting choroids discovered in the processes of model excavation after grouting. The empirical value of the "splitting-opening pressure" was put forward under similar condition of the soil layer. The laws of the soil strengthening effect affected by the grouting parameters and the improvement degree of the soil’s physical and mechanical properties after grouting were educed by means of doing conventional shear tests and consolidation tests towards the samples extracted in the soil affected by the grouting slurry and the undisturbed soil after grouting in the laboratory.更多还原