堤顶道路基层材料抗裂性能分析

发布时间：2019-03-19 22:15

【摘要】：水利堤坝填筑用土的要求区别于道路路基填料要求,指标不同、标准低;而施工控制中,土的击实标准低,压实标准也低。因而,与道路工程路基相比,堤顶道路路基的承载能力差,工后允许沉降大。在堤坝顶部修建硬化路面时,容易出现各种病害,堤顶道路的耐久性无法保障。论文分析了堤顶道路路基产生不均匀沉降变形时基层材料的力学响应,针对基层材料的性能、受力及变形特点,研究并提出合理的基层材料。论文采用有限元方法建立路面结构模型,分析半刚性基层材料在路基不均匀变形下的破坏模式;结合几种抗裂性试验方法进行半刚性基层的材料设计;进行室外足尺试验研究三种不同路面结构的荷载响应特性,对比了级配碎石基层与蜂巢-级配碎石复合基层抵抗路基不均匀变形的能力。希望通过半刚性基层材料和级配碎石基层抗裂能力的研究,改善和提高堤顶道路的服役寿命和服务水平。主要研究内容如下:首先,利用有限元分析软件Abaqus建立路面结构模型,分析沥青混凝土路面与水泥混凝土路面在路基沉降作用下,半刚性基层材料的受力特点,找到半刚性基层材料的控制指标。引入应力强度因子的概念,研究沉降量变化对层底拉应力与应力强度因子的影响,分析路基不均匀沉降导致半刚性基层材料开裂的机理。计算结果显示裂缝尖端处的应力强度因子随不均匀沉降量的增加而线性增长,说明沉降量的大小对半刚性基层裂缝的扩展有显著影响。其次,根据有限元仿真结果,进行了半刚性基层材料抗裂性能的试验分析。选取水泥稳定砂砾材料,拟定三种典型级配与三个水泥用量,采取不同的养生龄期。采用抗折试验与劈裂试验评价水泥稳定砂砾材料的抗裂能力,分析养生龄期、级配类型、水泥剂量对抗折强度与劈裂强度的影响规律。采用三点弯曲试验方法,引入断裂韧度与断裂能的概念评价水泥稳定砂砾材料的抗裂性能,取得了较好的效果。最后,采用足尺试验研究级配碎石基层的结构抗裂性能。铺筑三种路面结构,施加车辆荷载,通过预先埋置的传感器采集基层底面三个方向的应变及土压力。分析三种路面结构在轴载、加载位置、车速变化时的力学响应。以路基压实度的变化来间接反映路基的不均匀沉降,研究级配碎石基层材料与蜂巢-级配碎石复合基层材料抗变形能力。
[Abstract]:The requirements of filling soil for hydraulic dikes and dams are different from those for road roadbed filling, with different indexes and low standards, while in construction control, the compaction standard of soil is low and the standard of compaction is also low. Therefore, compared with road engineering roadbed, the bearing capacity of embankment roof roadbed is poor, and the allowable settlement after construction is large. During the construction of hardened road surface on the top of dyke, it is easy to occur various diseases, and the durability of dike roof road can not be guaranteed. This paper analyzes the mechanical response of the base material when the subgrade on the embankment roof produces uneven settlement deformation. According to the performance, force and deformation characteristics of the base material, the reasonable base material is studied and put forward. In this paper, the pavement structure model is established by finite element method, the failure mode of semi-rigid base material under uneven deformation of roadbed is analyzed, and the material design of semi-rigid base course is carried out with several crack resistance test methods. The load response characteristics of three different pavement structures were studied by outdoor full-scale test. The ability of graded crushed stone base and honeycomb-graded crushed stone composite base to resist uneven deformation of roadbed was compared. It is hoped that the service life and service level of dike top road can be improved by studying the crack resistance of semi-rigid base material and graded crushed stone base. The main research contents are as follows: firstly, the structure model of asphalt concrete pavement and cement concrete pavement is established by using finite element analysis software Abaqus, and the stress characteristics of semi-rigid base material under the action of subgrade settlement are analyzed. Find out the control index of semi-rigid base material. In this paper, the concept of stress intensity factor is introduced to study the influence of settlement on tensile stress and stress intensity factor of floor, and the mechanism of cracking of semi-rigid base material caused by uneven settlement of roadbed is analyzed. The calculated results show that the stress intensity factor at the crack tip increases linearly with the increase of non-uniform settlement, which indicates that the settlement has a significant effect on the crack propagation of semi-rigid base. Secondly, according to the finite element simulation results, the anti-crack performance of semi-rigid base material is tested and analyzed. The cement stabilized gravel material was selected, three typical gradation and three cement dosage were worked out, and different curing age was adopted. Fracture resistance test and splitting test were used to evaluate the anti-cracking ability of cement stabilized gravel materials. The effects of curing age, grading type and cement dosage on fracture strength and splitting strength were analyzed. The fracture toughness and fracture energy were introduced to evaluate the crack resistance of cement stabilized gravel materials by three-point bending test, and good results were obtained. Finally, the crack resistance of graded macadam base is studied by full-scale test. Three kinds of pavement structures are laid, vehicle loads are applied, and strain and earth pressure in three directions of the base layer are collected by pre-embedded sensors. The mechanical responses of three kinds of pavement structures under axial load, loading position and speed change are analyzed. The uneven settlement of subgrade is indirectly reflected by the change of subgrade compactness, and the anti-deformation ability of graded macadam base material and honeycomb-graded macadam composite base material is studied.
【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】：2017
【分类号】：U414

【参考文献】