巨粒填料蠕变沉降下的破碎及本构参数研究

发布时间：2018-10-26 19:04

【摘要】：由于机场施工建设本来要占用的场地区域大,因此就会产生许多的工程问题。我国西南地区具有复杂多变的地形地貌和地质条件,并且以高山、丘陵和沟谷等地形为主。西南地区机场建设的设计和施工,由于存在这两方面的原因,使得其要面对各种各样的工程难题,这其中就有工程质量要求高、场区地质条件复杂、挖填方土石量巨大、高边坡的稳定性、填方体的不均匀沉降以及对沉降的控制等问题。我国西南地区的机场建设中,大多会有大量的挖填土石方工程。由于填方区的填料往往是就地取材,所以填筑体多是将场区内岩石经爆破后产生的碎石料经人工填筑压实而成。这样的填料一方面往往存在岩体成分比较复杂、级配不良等问题,另一方面受填方体施工水平的影响,因此机场高填方往往在工后出现较大的沉降而发生不均匀沉降问题。除此之外西南地区多有短时强降雨天气,且降雨在一年之中分布比较集中,因此填料的湿陷沉降问题也十分突出,尤其在填料中存在有遇水易软化破碎的岩体时更为突出。本文就机场高填方填筑体在不同含水量条件下的蠕变沉降问题进行研究和探讨。首先以重庆新机场高填方砂泥岩巨粒碎石土填料作为试验研究对象,对其进行大型单轴侧限压缩和筛分实验研究。根据筛分实验结果计算破碎参量和分形维数,并建立与其他基本变量之间的相关关系。再用两种智能算法择优辨识出蠕变Cvisc模型参数,并建立与相对破碎率的关系,再得出不同含水量条件下本构参数的计算式,这样就可以在已知所受应力和含水量的情况下可以直接根据关系算出本构参数。最后对本构参数进行实验条件下数值模拟验证,证明了辨识出的本构参数的可用性。并建立机场道槽区剖面模型,在含水量5%和10%时,模拟其在本构参数分层和整体赋值的情况下的蠕变沉降特性,证明了分层赋值在预测机场高填方工后长期沉降方面,比整体赋值更具合理性,再比较了5%、10%与8%含水量,验证了得到的本构参数计算式的合理性。
[Abstract]:There are many engineering problems due to the large area of airport construction. The southwest of China is characterized by complex topography and geological conditions, and is dominated by alpine, hilly and gully terrain. The design and construction of the airport construction in southwest China, due to these two reasons, make it face various engineering difficulties. Among them, the engineering quality is high, the geological conditions in the field area are complex, and the amount of excavated and filled earth and rock is huge. Stability of high slope, uneven settlement of fill and control of settlement. In the airport construction in southwest China, there will be a large number of excavation and rock filling projects. Because the fillers in the filling area are usually based on local materials, most of the filling bodies are formed by artificial filling and compaction of the crushed stones produced by blasting in the field area. On the one hand, such fillers often have some problems such as complex rock mass composition and poor gradation, on the other hand, due to the influence of the construction level of the filling body, the problem of uneven settlement often occurs after the construction of the airport high fill. In addition, there are short and strong rainfall weather in southwest China, and the rainfall distribution is concentrated in one year, so the problem of collapsing settlement of fillers is also very prominent, especially when there are rock masses in which water is easy to soften and break. In this paper, the problem of creep settlement of airport high fill under different water content is studied and discussed. Firstly, the large scale uniaxial compression and sieving experiments were carried out on the high fill sand and mudstone giant grained gravel fillers of Chongqing New Airport. The breaking parameters and fractal dimension are calculated according to the results of sieving experiment, and the correlation between them and other basic variables is established. Then two intelligent algorithms are used to identify the parameters of creep Cvisc model, and the relationship between creep parameters and relative breakage rate is established, and then the formula of constitutive parameters under different water content is obtained. In this way, the constitutive parameters can be calculated directly according to the relation when the stress and water content are known. Finally, the availability of the identified constitutive parameters is proved by numerical simulation under the experimental conditions. At the same time, the section model of the channel area of the airport is established. When the water content is 5% and 10%, the creep settlement characteristics are simulated under the condition of the stratification of constitutive parameters and the integral assignment. It is proved that the stratified assignment can predict the long-term settlement after the construction of the airport high fill. It is more reasonable than the whole assignment. The calculation of constitutive parameters is proved to be reasonable by comparing the water content of 5% and 8%.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU433

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