CBFRC力学性能试验研究及其复合路面结构分析

发布时间：2018-10-15 18:31

【摘要】：短切玄武岩纤维增强橡胶混凝土(Chopped Basalt Fiber reinforced Rubber Concrete,简称CBFRC)是将短切玄武岩纤维加入到橡胶混凝土中,通过与柔性材料橡胶颗粒的复合作用,在有效降低混凝土的弹性模量的同时,增强混凝土的抗压和抗折强度,为水泥混凝土路面减震降噪提供了可能。本文对CBFRC的立方体抗压强度、轴心抗压强度、静力受压弹性模量、抗折强度等力学性能进行了试验研究。同时提出了CBFRC-RCC复合式路面结构,并对其车载应力进行有限元分析。具体研究成果如下:(1)随着橡胶颗粒掺量的增加,混凝土立方体抗压强度、轴心抗压强度在逐渐减小。橡胶颗粒掺量在0~20%时,混凝土强度降低缓慢,此后随着橡胶颗粒掺量增加而迅速下降,当橡胶颗粒掺量达到50%时,其强度已不能满足公路路面力学性能的要求。同时橡胶颗粒的掺入也改善了混凝土的破坏形态,其韧性明显增强。(2)随着橡胶颗粒掺量的增加,橡胶混凝土的静力受压弹性模量在逐渐减小。橡胶颗粒掺量在0~30%时,混凝土强度降低缓慢,此后随着橡胶颗粒掺量增加而迅速下降。同时基于试验值回归分析,建立了静力受压弹性模量与立方体抗压强度的关系式。橡胶颗粒掺量在0~50%时,混凝土泊松比从0.1823升高到0.2125。(3)0.2%短切玄武岩纤维掺入橡胶混凝土中后,其立方体抗压强度、轴心抗压强度、弹性模量及泊松比的试验点与原橡胶混凝土试验点几乎重合,说明加入玄武岩纤维对混凝土的上述力学性能影响较小。(4)随着橡胶掺量的增加,混凝土的抗折强度逐渐降低,而随短切玄武岩纤维掺量的增加,橡胶混凝土抗折强度,又有明显的提高。(5)橡胶混凝土的立方体抗压强度与抗折强度之比k(k亦称为脆性系数)随橡胶掺量的增加而减小,并且短切玄武岩纤维的掺入可以进一步降低k。(6)通过有限元软件的模拟分析,获得了CBFRC-RCC复合路面结构在车载应力下的变化规律:1)混凝土弹性模量的增加使相邻层板底应力减小,本层板底应力增大;2)当复合路面板总厚度增大时,下层板底应力减小,但上层板底拉应力则随上、下面层板相对厚度的减小而增大;3)上、下层板底应力随路基顶面当量回弹模量Et的增大均减小。(7)根据上、下层路面板厚度、弹性模量以及路基顶面当量回弹模量Et对复合路面板底应力的影响规律,在CBFRC-RCC复合路面设计过程中,减小板底应力可采取的措施有:1)适当增大上层CBFRC的弹性模量、减小下层RCC的弹性模量;2)当复合路面板总厚度一定时,适当增加上层CBFRC板厚、减小下层RCC板厚;3)适当增大地基顶面当量回弹模量Et。
[Abstract]:Short cut basalt fiber reinforced rubber concrete (Chopped Basalt Fiber reinforced Rubber Concrete,) is a kind of short cut basalt fiber which is added to rubber concrete. By combining with flexible rubber particles, the elastic modulus of concrete can be reduced effectively at the same time. Strengthening the compressive and flexural strength of concrete provides the possibility for reducing vibration and noise of cement concrete pavement. In this paper, the mechanical properties of CBFRC such as cube compressive strength, axial compressive strength, static compressive elastic modulus and flexural strength are studied experimentally. At the same time, the CBFRC-RCC composite pavement structure is put forward, and the stress on the vehicle is analyzed by finite element method. The specific research results are as follows: (1) with the increase of rubber particle content, the compressive strength and axial compressive strength of concrete cube gradually decrease. When the content of rubber particles is 0 ~ 20, the strength of concrete decreases slowly, and then decreases rapidly with the increase of the content of rubber particles. When the content of rubber particles reaches 50, its strength can not meet the requirements of the mechanical properties of highway pavement. At the same time, the addition of rubber particles also improves the failure form of concrete, and its toughness is obviously enhanced. (2) with the increase of rubber particle content, the static compressive elastic modulus of rubber concrete decreases gradually. When the content of rubber particles is 0 ~ 30, the strength of concrete decreases slowly, and then decreases rapidly with the increase of the content of rubber particles. At the same time, based on the regression analysis of the experimental values, the relationship between the compressive modulus of static compression and the compressive strength of the cube is established. The Poisson's ratio of concrete increases from 0.1823 to 0.2125 when the amount of rubber particles is 0 ~ 50. (3) when 0.2% short cut basalt fiber is mixed into rubber concrete, its cube compressive strength and axial compressive strength are obtained. The experimental sites of elastic modulus and Poisson's ratio almost coincide with the original rubber concrete test site, which indicates that the addition of basalt fiber has little effect on the above mechanical properties of concrete. (4) with the increase of rubber content, the flexural strength of concrete decreases gradually. However, with the increase of the content of short cut basalt fiber, the flexural strength of rubber concrete increases obviously. (5) the ratio of cube compressive strength to flexural strength of rubber concrete, k (also known as brittleness coefficient), decreases with the increase of rubber content. And the incorporation of short cut basalt fiber can further reduce k.( 6) through the simulation analysis of finite element software, the variation law of CBFRC-RCC composite pavement structure under on-board stress is obtained: 1) the bottom stress of adjacent laminate decreases with the increase of elastic modulus of concrete. The bottom stress of the laminate increases with the increase of the total thickness of the composite slab, but the tensile stress of the bottom increases with the decrease of the relative thickness of the laminate. 3) on the top, the tensile stress of the bottom of the laminate increases with the increase of the total thickness of the composite slab, and the tensile stress increases with the decrease of the relative thickness of the laminate. The bottom stress of the subgrade decreases with the increase of the equivalent modulus of resilience (Et) of the top surface of the roadbed. (7) according to the influence of the thickness of the upper and lower face slab, the elastic modulus and the equivalent modulus of resilience of the top surface of the roadbed, Et on the bottom stress of the composite pavement slab, In the design process of CBFRC-RCC composite pavement, the following measures can be taken to reduce the slab bottom stress: 1) to increase the elastic modulus of the upper layer of CBFRC and to decrease the elastic modulus of the lower layer of RCC; 2) to increase the thickness of the upper layer of CBFRC plate when the total thickness of the composite road panel is fixed. Reduce the thickness of the lower RCC plate; 3) increase the equivalent modulus of springback Et. of the top surface of the foundation appropriately
【学位授予单位】：河南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414;U416.2

【相似文献】