CDM法拌合体受力特性及破坏机理研究

发布时间：2018-03-26 22:26

本文选题：CDM法　切入点：复合基础　出处：《大连理工大学》2015年硕士论文

【摘要】：较厚的软土往往限制了重力式结构在港口工程中的应用,传统地基处理方式在提高地基承载力方面差强人意。水下深层搅拌法(CDM法)以其良好的地基改良特性以及较少的海区污染,在北欧以及日本等国家被广泛应用于港口工程地基加固。然而在我国,CDM法由于施工工艺及设备短缺、加固费用昂贵等原因,并未得到广泛的推广本文首先根据中日CDM规范以及工程设计经验,归纳CDM的破坏模式,总结各破坏模式验算方法。并比较我国《水下深层水泥搅拌法加固软土地基技术规程》、日本《海上工事深层混合处理工法技术手册》、日本《港口技术基准·同解说》设计计算理论差异。CDM法壁式拌合体地基破坏模式可分为横向整体破坏与壁间破坏,但我国相关规范中缺少对壁式拌合体壁间地基破坏的验算。因此本文在Prandtl解滑裂线的基础上,假定滑裂线过渡区与被动区的连续性,推导出复合基础地基破坏滑裂线形状。根究该滑裂线形状,本文采用条分法计算复合基础地基地基承载力,并通过FLAC 3D验算其合理性。之后,运用FLAC 3D验证两种破坏模式的独立性。本文根据该方法并结合《港口工程地基规范》提出了壁式拌合体地基承载力验算的新判据。块式拌合体着底形式可分为悬浮式和着底式。现行规范中对两种着底形式的拌合体基底压力计算假定均为线性分布。根据本文有限元分析结果,悬浮和着底式拌合体基底压力由于下卧土层的塑性变形以及刚度的影响,除趾部小部分的应力集中区域外,最大基底压力产生于趾部里侧。并且根据数值模拟结果,拌合体内剪力最大值产生位置与规范计算假定相同。现行中日规范中壁式拌合体抗压验算中,均假定长壁承担所有上部荷载。根据本文数值模拟结果,由于壁间土的桩侧摩阻力作用以及壁间土对短壁的地基反力的作用,壁间土承担了一定的竖向荷载。并且长壁最大竖向应力并不一定出现在长壁底部。该现象对于悬浮式拌合体尤为如此。此外,本文根据某实际工程案例,对比分析各种地基处理方案,并且验算上部结构沿基床内部滑裂面抗滑稳定性。
[Abstract]:Thick soft soil often limits the application of gravity structures in port engineering. The traditional method of foundation treatment is not satisfactory in improving the bearing capacity of foundation. The underwater deep mixing method and CDM method have good foundation improvement characteristics and less pollution in the sea area. In northern Europe and Japan and other countries are widely used in port engineering foundation reinforcement. However, in China, because of the shortage of construction technology and equipment, the cost of reinforcement is expensive. Firstly, according to the CDM code and engineering design experience of China and Japan, the failure mode of CDM is summarized. This paper summarizes the checking calculation methods of each failure mode, and compares the Technical regulations for strengthening soft soil Foundation by underwater Deep cement mixing method in China, the Technical Manual of Deep mixing treatment method for Offshore works in Japan, and the same solution of Technical Datum of Ports in Japan. Theory difference of Design and calculation. Failure modes of Wall-type mixed Foundation with CDM method can be divided into transverse whole failure and interwall failure. However, there is a lack of checking calculation of the foundation failure between wall and wall in the relevant codes of our country. Therefore, on the basis of Prandtl solution of sliding crack line, the continuity of transition zone and passive zone of sliding crack line is assumed in this paper. In this paper, the bearing capacity of composite foundation is calculated by slice method, and its rationality is verified by FLAC 3D. FLAC 3D is used to verify the independence of the two failure modes. In this paper, a new criterion for checking the bearing capacity of wall mixed foundation is put forward according to this method and combining with the Code of Foundation for Port Engineering. The bottom form of block mixed body can be divided into suspension. In the current code, the calculation of the pressure of two kinds of bottom mixed body is assumed to be linear distribution. According to the results of finite element analysis in this paper, Under the influence of plastic deformation and stiffness of the underlying soil, the maximum base pressure is generated from the inner side of the toe, except for the stress concentration area in a small part of the toe, and according to the results of numerical simulation. The position of the maximum shear force in mixing body is assumed to be the same as that in the code. In the current Chinese and Japanese codes, the wall bearing all the upper loads is assumed to bear all the upper loads. According to the results of numerical simulation in this paper, Because of the effect of pile friction on the soil between the walls and the reaction of the soil between the walls to the foundation of the short wall, The soil between walls bears a certain vertical load, and the maximum vertical stress of the long wall does not necessarily appear at the bottom of the wall. This phenomenon is especially true for suspension mixing. In addition, according to a practical engineering case, All kinds of foundation treatment schemes are compared and analyzed, and the anti-slide stability of superstructure along the sliding surface of the bed is checked.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U655.54

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