单纤维与水泥土基体拉拔模拟与破坏机理研究

发布时间：2018-06-13 14:42

本文选题：纤维加筋水泥土 + 数值模拟　；参考：《浙江海洋大学》2017年硕士论文

【摘要】：舟山地区存在大量的淤泥质软土,在软土上建造建筑物有很多不利的因素,比如海水中含有大量的离子成分造成了水泥土的后期强度不高、成型质量较差,容易发生膨胀产生裂纹等工程问题,在实际工程中人们常常在水泥土中添加一些纤维来改善其性能,抑制裂纹的发展,提高水泥土的强度。本文在前人研究的基础上利用土壤张拉试验仪、传感器、千分表等仪器进行聚丙烯纤维单丝拉拔试验,测试埋入长度为5mm、10mm、15mm的聚丙烯单丝纤维在3、7、28、90天期龄的纤维拉力随滑动位移的变化规律,通过纤维拉力-位移曲线分析纤维在滑动过程中的拉力变化。通过有限元软件ABAQUS建立二维和三维单纤维拉拔有限元模型,运用粘滞理论计算纤维在脱粘和拔出过程中界面剪应力的变化,对比粘滞理论计算结果和数值模拟结果,验证单纤维拉拔二维、三维有限元模型构建的合理性。在二维、三维模型构建合理的基础上,变换纤维与水泥土基体之间的摩擦系数、纤维的弹性模量、纤维端部粘结力、纤维的掺入量、纤维的埋入长度、接触界面属性、渐变层厚度、纤维与水泥土基体的弹塑性、粘性单元参数等因素,探究这些因素对纤维拉力-位移曲线的影响。在保持纤维掺量、纤维长度、接触条件等因素相同的条件下,考虑界面单元时,三维模拟得出的拉力-位移曲线与试验测出的拉力-位移曲线很相近,说明界面层是影响纤维拉力的一个很重要的因素,界面层的破坏是纤维加筋失效的根本原因,这对以后纤维加筋技术相关的研究具有极大的指导意义。
[Abstract]:There are a large number of silt soft soil in Zhoushan area, and there are many unfavorable factors for building on soft soil. For example, a large amount of ionic composition in seawater results in low later strength and poor molding quality of cement soil. Engineering problems such as expansion and crack are easy to occur. In practical engineering, people often add some fibers to cement soil to improve its performance, restrain the development of cracks, and improve the strength of cement soil. On the basis of previous studies, this paper makes use of soil tensioning test instrument, sensor, meter and other instruments to carry out the drawing test of polypropylene fiber monofilament. The tensile force of polypropylene monofilament fibers with embedded length of 5 mm ~ 10 mm ~ (15 mm) at the age of 3 ~ 7 ~ 28 ~ 90 days was measured. The tensile force of the fibers during sliding was analyzed by means of the tension-displacement curves of the fibers. The finite element models of 2D and 3D single fiber drawing were established by Abaqus, and the shear stress of the interface during debonding and pullout of the fibers was calculated by using the viscosity theory. The calculated results of the viscosity theory and the numerical simulation results were compared. Verify the rationality of two-dimensional and three-dimensional finite element model of single fiber drawing. Based on the reasonable construction of 2D and 3D models, the friction coefficient between fiber and cement soil matrix, the elastic modulus of fiber, the adhesive force at the end of fiber, the content of fiber, the length of fiber embedding, the properties of contact interface are transformed. The influence of the factors such as the thickness of the graded layer, the elastoplasticity of the fiber and the cement soil matrix, and the parameters of the viscous element on the tension displacement curve of the fiber are investigated. Under the condition of keeping the same amount of fiber, fiber length, contact condition and so on, when the interface element is considered, the tension displacement curve obtained by 3D simulation is very close to the tension displacement curve measured by experiment. It shows that the interfacial layer is a very important factor affecting the fiber tension, and the failure of the interfacial layer is the fundamental cause of fiber reinforcement failure, which is of great significance to the research of fiber reinforcement technology in the future.
【学位授予单位】：浙江海洋大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU43

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