施工期荷载及养生龄期对水泥稳定碎石结构层损伤的影响

发布时间：2018-09-02 07:45

【摘要】：目前国内各规范对施工期荷载没有严格的规定,也没有考虑施工车辆荷载对路面结构设计的影响;此外,在半刚性基层沥青路面施工过程中,由于受季节及工期限制,赶工期的现象比较常见,一般铺筑7d后或在较短的龄期下(未达到90d或180d)即进行上层结构的铺筑,养生车辆、运料车辆、摊铺机和碾压机等施工设备必然会对还未形成强度、刚度的下承层产生破坏,在施工期即产生了路面结构的内部损伤,使水泥稳定碎石基层结构产生微裂缝,为早期的损坏埋下隐患。虽然在通车初期基层微裂缝对路用性能没有影响,但是在交通荷载的反复作用下基层结构的强度急剧下降,裂缝扩展,严重影响道路的路用性能和使用寿命。从旧路改造的施工中,我们可以看到施工车辆荷载对路面损伤的严重性,所以新建道路施工期荷载与非荷载因素(养生龄期、温度)对道路可能产生先天损伤,使道路在运营后不久便产生各种不同程度的破坏。本研究通过对施工车辆荷载统计研究,采用理论分析与试验的方法对水泥稳定碎石结构层进行损伤分析。首先,为了模拟施工过程可能遇到的天气状况,采用了不同的养生温度,对水泥稳定碎石材料进行不同龄期的养生,然后进行无侧限抗压强度、劈裂强度、抗压回弹模量试验。结果表明:低温对水泥稳定材料的强度、模量有很大影响,低温下材料的强度、模量都处于较低水平,尤其是低温低龄期下,材料的各项指标都很低。其次,基于施工期的车辆荷载作用,采用ABAQUS有限元软件,并结合试验数据,计算了水泥稳定碎石底基层的层底拉应力,提出了施工期底基层不发生极限破坏时所需要的养生时间和允许的荷载范围。最后,进行了不同养生温度和龄期下的弯拉强度试验,在此基础上,进行了低龄期不同温度下的弯拉疲劳试验,建立了室内低龄期的疲劳预估模型。然后采用Miner线性损伤理论,对施工期不同工况下底基层的损伤进行分析。结果表明:底基层在荷载直接作用下损伤最大,即在施工下基层时对底基层的损伤最为严重。通过分析,得出可以通过增加底基层材料强度、厚度、增长养生龄期来减小施工荷载对底基层的损伤。
[Abstract]:At present, there are no strict regulations on the load during the construction period and no consideration of the influence of the load of the construction vehicle on the design of the pavement structure. In addition, in the construction process of the semi-rigid base asphalt pavement, due to the limitation of the season and the duration of the construction period, The phenomenon of time delay is quite common. Generally speaking, after 7 days of paving or under a shorter age (less than 90 days or 180 days), the construction equipment of the upper structure, health vehicles, transport vehicles, pavers and compactors will inevitably have not formed the intensity of the construction equipment. During the construction period, the internal damage of the pavement structure is produced, which makes the cement stabilized crushed stone base structure produce micro-cracks, which is the hidden danger for the early damage. Although there is no effect of micro-cracks on the road performance in the initial stage of traffic, the strength of the base structure decreases sharply under the repeated action of traffic load, and the crack expands, which seriously affects the road performance and service life of the road. From the construction of the old road reconstruction, we can see the severity of the road damage caused by the load of the construction vehicle, so the load and non-load factors (health age, temperature) may cause congenital damage to the road during the construction period of the new road. Causes the road soon after the operation produces each kind of degree of destruction. In this study, the damage analysis of cement stabilized crushed stone structure layer is carried out by means of theoretical analysis and test method through the statistical research on the load of construction vehicles. Firstly, in order to simulate the weather conditions that may be encountered in the construction process, different curing temperatures are used to carry out the tests of unconfined compressive strength, splitting strength and compressive resilience modulus of cement-stabilized macadam materials at different ages. The results show that the strength and modulus of the cement stabilized material are greatly affected by low temperature. The strength and modulus of the material are all in low level at low temperature, especially in the low temperature and low age period, all the indexes of the material are very low. Secondly, based on the vehicle load during construction, the tensile stress of cement stabilized gravel base is calculated by using ABAQUS finite element software and test data. At the end of the construction period, the required health time and the allowable load range for the base course without ultimate failure are put forward. Finally, the flexural tensile strength tests at different health temperatures and ages were carried out. On the basis of these tests, bending tension fatigue tests at different temperatures in the lower age period were carried out, and a fatigue prediction model for the lower age period was established. Then the Miner linear damage theory is used to analyze the damage of the base under different working conditions. The results show that the damage of the base is the most serious under the direct action of the load, that is, the damage to the base is the most serious when the base is under construction. Through analysis, it is concluded that the damage caused by construction load on the base can be reduced by increasing the strength, thickness and health age of the base material.
【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】：2015
【分类号】：U416.214

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