大型模袋砂围堰稳定性及变形特性研究

发布时间：2018-03-23 13:58

本文选题：模袋砂围堰　切入点：稳定性　出处：《华南理工大学》2014年硕士论文

【摘要】：模袋砂围堰由于施工简便、污染少、机械化程度高、易于拆除等优点被广泛应用于江、河、湖、海的近岸港湾、码头等临时围堰工程建设中。但由于模袋砂力学性状的复杂性，目前对模袋砂围堰的稳定性分析、变形特性研究和模袋抗拉强度计算还有待完善。因此，本文在开展了模袋砂增强机理分析，室内试验研究的基础上，对模袋砂围堰进行了稳定性分析、断面设计方法探讨、变形特性研究及模袋抗拉强度计算。本文主要研究内容及取得的成果如下：（1）分析了模袋砂增强机理，推导了模袋砂极限压应力理论解析解，进行了模袋砂室内单轴压缩试验和水平加载试验，得到了模袋砂竖向、横向应力—应变关系曲线，分析了模袋砂竖向、横向力学性状。分析结果表明，模袋砂并不是各向均质体，横向与竖向力学性状并不相同，其水平变形模量远远小于竖向变形模量，且随着上覆荷载的增大，模袋砂水平变形模量也逐渐增大。（2）建立了模袋砂围堰稳定性分析简化模型，提出了围堰稳定性计算方法，推导了围堰稳定性计算公式。以广州市洲头咀隧道第二次围堰工程为背景，对不同坡度、不同顶宽模袋砂围堰进行了稳定性计算，分析了模袋砂围堰稳定安全系数变化规律。分析结果表明，围堰安全系数随着坡度的变缓、顶宽的增大而增大，且围堰稳定由外部稳定性控制。（3）优化了模袋砂围堰稳定性计算公式，对围堰断面设计方法进行了探讨研究；且从稳定分析角度，在满足稳定安全系数要求时，推导了围堰最小断面面积计算公式；并运用MATLAB数学软件，编制了搜索围堰最优顶宽b和坡度i的程序代码，提出了模袋砂围堰最优断面设计的计算方法。（4）结合广州市洲头咀隧道第二次围堰工程设计及实施情况，对围堰进行了稳定性验算；建立了围堰数值分析模型，研究了下游降水过程中围堰的变形特性；结合模袋砂变形计算结果，对模袋进行了抗拉强度验算。结果表明，，模袋内形成稳定水位时，围堰变形趋于稳定；随着下游水位的降低，围堰变形逐渐增大，模袋拉应力也随之增大。（5）总结了模袋砂围堰的变形规律，提出了模袋砂围堰的变形计算方法。将计算结果和实测值进行了对比分析，对比结果表明文中建模方法的合理性和有效性。
[Abstract]:Due to the advantages of simple construction, less pollution, high mechanization and easy to be dismantled, the sand cofferdam is widely used in the construction of temporary cofferdam projects such as river, river, lake, sea near shore, wharf, etc. However, due to the complexity of mechanical properties of moulded bag sand, At present, the stability analysis, deformation characteristic research and tensile strength calculation of mold bag sand cofferdam need to be improved. The stability analysis, section design method, deformation characteristic research and tensile strength calculation of mold bag sand cofferdam are carried out. The main contents and results of this paper are as follows:. In this paper, the strengthening mechanism of mold bag sand is analyzed, the analytical solution of ultimate compressive stress is deduced, the uniaxial compression test and horizontal loading test are carried out, and the vertical and transverse stress-strain relationship curves are obtained. The vertical and transverse mechanical properties of moulded bag sand are analyzed. The results show that the sand is not homogenized in each direction, and its horizontal deformation modulus is much smaller than that of vertical deformation, and the lateral and vertical mechanical properties are different. And with the increase of overburden load, the horizontal deformation modulus of sand-bag sand increases gradually. (2) A simplified model for stability analysis of sand cofferdam with moulded bag is established, a method for calculating the stability of cofferdam is put forward, and a formula for calculating the stability of cofferdam is derived. Taking the second cofferdam project of Guangzhou Zhoutou Tunnel as the background, the slope of the second cofferdam is studied. The stability calculation of sand cofferdam with different top width is carried out, and the variation law of stability safety factor of sand cofferdam is analyzed. The results show that the safety factor of cofferdam increases with the increase of slope, and the width of sand cofferdam increases with the increase of top width. The stability of cofferdam is controlled by external stability. (3) the formula for calculating the stability of sand cofferdam is optimized, and the design method of cofferdam section is studied, and the formula for calculating the minimum section area of cofferdam is derived from the point of view of stability analysis when the requirement of stability safety factor is satisfied. The program code of searching the optimum top width b and slope I of cofferdam is compiled by using MATLAB software, and the calculation method of optimum section design of sand cofferdam with mould bag is put forward. 4) based on the design and implementation of the second cofferdam in Guangzhou City, the stability of the cofferdam is checked, and the numerical analysis model of the cofferdam is established, and the deformation characteristics of the cofferdam in the process of downstream precipitation are studied. Combined with the calculation results of sand deformation in mold bag, the tensile strength of die bag is checked. The results show that the cofferdam deformation tends to be stable when the stable water level is formed in the mold bag, and the cofferdam deformation increases gradually with the decrease of downstream water level. The tensile stress of die bag also increases. (5) the deformation law of sand cofferdam is summarized, and the method of calculating the deformation of sand cofferdam is put forward. The results are compared with the measured values, and the results show that the modeling method is reasonable and effective.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV551.3

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