基于随机场理论的水泥混凝土路面结构可靠性分析

发布时间：2018-06-24 21:21

本文选题：水泥混凝土路面 + 随机场　；参考：《哈尔滨工业大学》2014年硕士论文

【摘要】：在我国，水泥路面结构是十分重要的路面结构形式之一，无论是在高等级公路中还是在低等级公路中都有十分广泛的应用。评价水泥路面质量的一个十分重要的指标是路面结构的可靠度，这也是水泥路面结构研究的一个重要内容。水泥路面结构的尺寸、材料性能和作用荷载均具有不确定性，如何更加准确的描述上述随机因素、选择适合的可靠性分析方法以及分析随机因素对结构可靠性的影响是本文研究的主要内容。 (1)首先分析影响水泥路面结构可靠性的随机因素，主要有累计标准轴载作用次数、轴载、混凝土弯拉强度、温度梯度、各结构层材料的模量、混凝土板厚度。根据上述因素的特点，将面层、基层和土基模量模拟为二维随机场，其他因素模拟为随机变量。根据局部平局法将模量随机场离散为随机变量，计算了协方差矩阵与相关系数矩阵。 (2)然后基于Ansys软件，建立水泥路面结构有限元模型，同时验证了模型的正确性。将上述随机变量作为输入变量，，分布形式均采用截断的正态分布，根据Ansys/PDS模块提供的蒙特卡罗法，计算了混凝土板疲劳断裂和极限断裂两种极限状态情况下的结构失效概率，分析了对结构可靠性影响较大的随机因素，主要有混凝土板厚度、轴载、混凝土弯拉强度和面层模量。并对比分析了模量的随机场模型和随机变量模型对结构失效概率的影响，结果表明模量随机变量模型计算的失效概率要大于模量随机场模型计算的失效概率。 (3)最后分析了轴载、材料模量、混凝土板厚度、面层与基层的接触条件和温度梯度与车辆荷载综合作用对路面结构可靠性的影响。结果表明，板厚均值、面层模量均值和轴载对水泥路面结构可靠性影响显著，板厚、面层模量变异系数相比于均值来说，对结构可靠性影响较小；面层与基层的摩擦系数与结构失效概率的关系曲线存在临界点，控制摩擦系数大于该点对于提高结构可靠性十分有益；温度梯度与车辆荷载综合作用对结构可靠性影响十分显著，正温度梯度时结构失效概率明显大于未考虑温度梯度与车辆荷载综合作用时结构的失效概率，而负温度梯度时结构失效概率很小。
[Abstract]:In China, cement pavement structure is one of the most important pavement structure forms. It is widely used in high grade highway and low grade highway. A very important index to evaluate the quality of cement pavement is the reliability of pavement structure, which is also an important content in the study of cement pavement structure. The size, material performance and action load of cement pavement structure are uncertain. How to describe the random factors more accurately, Choosing suitable reliability analysis methods and analyzing the influence of random factors on structural reliability are the main contents of this paper. (1) the random factors affecting the structural reliability of cement pavement are analyzed firstly. There are mainly accumulative standard axial loads, flexural tensile strength of concrete, temperature gradient, modulus of each structural layer material, thickness of concrete slab. According to the characteristics of the above factors, the modulus of the surface layer, the base layer and the soil foundation is simulated as a two-dimensional random field, while the other factors are simulated as random variables. According to the local draw method, the modulus random field is discretized into random variables, the covariance matrix and the correlation coefficient matrix are calculated. (2) based on Ansys software, the finite element model of cement pavement structure is established, and the correctness of the model is verified. The random variables mentioned above are taken as input variables. The distribution forms are truncated normal distribution. According to Monte Carlo method provided by Ansys / PDS module, the failure probability of concrete slab under two limit states of fatigue fracture and ultimate fracture is calculated. The random factors affecting the reliability of the structure are analyzed, including the thickness of concrete slab, the axial load, the flexural tensile strength of concrete and the modulus of the surface layer. The effects of random field model of modulus and random variable model on failure probability of structure are compared and analyzed. The results show that the failure probability calculated by the modulus random variable model is greater than that calculated by the modulus random field model. (3) finally, the axial load, the modulus of material and the thickness of concrete slab are analyzed. The influence of the contact condition between the surface layer and the base course and the effect of temperature gradient and vehicle load on the reliability of pavement structure. The results show that the mean value of plate thickness, the average modulus of surface layer and the axial load have a significant effect on the reliability of cement pavement structure, and the coefficient of variation of slab thickness and modulus of surface layer have less effect on the reliability of cement pavement compared with the average value. There is a critical point in the curve between the friction coefficient of the surface layer and the base layer and the failure probability of the structure. It is very beneficial to control the friction coefficient larger than this point to improve the reliability of the structure. The effect of temperature gradient and vehicle load synthesis on the structural reliability is very significant. The failure probability of the structure under the positive temperature gradient is obviously higher than that of the structure without considering the comprehensive effect of the temperature gradient and the vehicle load. However, the failure probability of the structure is very small when the temperature gradient is negative.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U416.216

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