【作者】 石澍；

【导师】 邱红胜；

【作者基本信息】 武汉理工大学 ， 道路与铁道工程， 2012， 硕士

【摘要】 随着我国经济持续高速发展,大规模的基础设施建设依然方兴未艾。我国幅员辽阔,地质条件复杂,在各种建设中不可避免地会遇到各种类型软弱地基需要处理；同时在由于经济技术的进一步发展,原来许多被认为是良好建筑场地的地基也可能不再能满足设计要求而需要进行加固处理。碎石桩法是我国公路软基处理中一种常用的简便处理方法,但碎石桩强度较低,处理的地基深度有限；注浆法则是在工民建地基加固工程中的常用方法,具有设备简单、施工方便,但加固的可靠性不高。墩式碎石注浆则是结合桩碎石桩和注浆法这两种加固方法的一种新型的软基处理技术。对于这种新型注浆桩,本文主要做了以下及方面的工作：(1)总结了碎石注浆桩复合地基技术,在此基础上提出来了墩式碎石注浆桩复合地基技术及施工工艺,并拓宽了其加固工程应用范围。(2)应用有限元软件ABAQUS分析了墩式碎石注浆桩复合地基的加固机理、荷载传递特点,重点分析了不同性质的荷载下及不同浆液影响区置换率对桩的工作性状的影响。(3)结合某建筑基础加固工程实例,研究了墩式碎石注浆桩在刚性荷载下的工作性状；结合高速铁路工后沉降控制的实例,研究了墩式碎石注浆桩在柔性荷载下的工作性状。通过以上研究,主要得出了以下主要结论：(1)根据加固对象、注浆时机的不同,墩式碎石注浆桩复合地基处理技术可分为前加固和后加固两类,在这两种情况下墩式碎石注浆桩的作用、构造不完全相同。(2)墩式碎石注浆桩复合地基核心仍然是桩土共同作用,技术的关键有两点：一是在软土地基中,通过设置墩头,用以调节桩土,减少桩体上、下端的刺入变形；二是通过二次注浆或多次补浆,可以提高桩体的完整性,增加桩侧和桩端摩阻力。(3)墩式碎石注浆的P-S曲线依然遵循双曲线模型,没有明显拐点,桩的极限承载力宜根据沉降量确定。(4)利用墩式碎石注浆加固既有基础时,通过浅层注浆和深层注浆相结合的方法,加固效果较好。(5)墩式碎石注浆桩适用于对工后沉降要求严格的软土地基。尤其是在路基加固层弹性模量较小时,加固效果更为理想。更多还原

【Abstract】 Coupled with the continuous and rapid economical development of China, construction and development of large-scale are still growing. China has a vast territory, terrain complex geological conditions, inevitably, soft soil and other highly compressible soft soils, which used to be considered technically unsuitable for construction, are encountered. Gravel pile is a common simple foundation treatment method of the soft ground in the China’s highway engineering, but the strength of gravel pile is low and the depth of the foundation this method of processing is limited; on the other hand, the grouting is provided with simple equipment and convenient construction, but has poor reliability.. The Frustra-like crushed stone grouting pile is a new type of foundation treatment technology which is combined with pile of gravel piles and post-grouting technology.In this paper, the following work is mainly done for this new type of grouting pile:(1) The gravel grouting pile composite foundation is summarized, frustra-like crushed stone grouting pile composite foundation and construction technology is put out, and the scope of application of the grouting pile is broaden.(2) By using element software ABAQUS to analyze the mechanism of reinforcement of the frustra-like crushed stone grouting pile composite foundation, the load transfer characteristics, and the influence of the replacement ratio of the serous influence zone land the load stiffness to this pile are mainly studied.(3) With a building foundation reinforcement, the working properties of frustra-like crushed stone grouting pile under rigid load is studied; with a highway foundation reinforcement, this pile under flexible load is studied.Based on the researches mentioned above, the following conclusions can be drawn:(1) The frustra-like crushed stone grouting pile composite ground can be classified into two categories:preliminary reinforcement and post reinforcement. In these two conditions, the mechanization and the structure of pile is not identical. (2) The emphasis focal point of frustra-like crushed stone grouting pile composite ground is also the interaction between column and soil. And the key techniques are as follows. The first is pile cap, it is used for adjusting the stress of column and soil and reducing the penetration deformation at the top and bottom of the pile The second is grouting, it can increase the integrality and pile tip resistance, side friction.(3) The P-S curve of frustra-like crushed stone grouting pile also follows the hyperbolic model, and has no marked inflexion. The bearing capacity of crushed-stone grouting column should be determined based on the settlement value.(4) When reinforcing the existing foundation with frustra-like crushed stone grouting pile, a combination of shallow grouting and deep grouting can have a good reinforcement.(5) The frustra-like crushed stone grouting pile composite ground is applicable for the soft soil foundation. Specially, the effect is better when the foundation has a low elastic modulus.更多还原