IOCAS-IR
黄河三角洲浅层沉积物固结压实的时空变化及分布特征
其他题名Spatial-temporal variations and distribution characteristics in subsidence due to the natural consolidation and compaction of sediment in the Yellow River Delta,China
张翼
学位类型博士
导师黄海军
2018-05-15
学位授予单位中国科学院大学
学位授予地点中国科学院海洋研究所
学位名称理学博士
学位专业海洋地质
关键词黄河三角洲 浅层沉积物 固结压实 蒙特卡洛模型 Insar技术
摘要

过去十年,全球绝大多数三角洲都遭受了严重的洪水入侵和湿地退化等自然灾害,受灾人口达3亿,受灾面积高达260,000 km2 。大量研究证实,由三角洲下覆沉积地层的固结压实产生的地面沉降是造成三角洲脆弱的主要因素。得益于先进的技术和完备的观测网络,如密西西比三角洲的地面沉降现象与影响机制得到了较好的研究和分析,受技术和观测装备的制约,我国的三角洲地面沉降研究起步晚、数据少,方法落后,研究水平低。而且,像黄河三角洲这种独特的河控三角洲,受水盆地浅,来沙量巨大,河流多次改道,多期叶瓣交错叠置,其沉积物固结压实呈现出独特的时空变化特征。

有别于以往传统的以钻孔和剖面来计算、分析沉积地层的固结压实特征,本文在广泛收集黄河三角洲钻孔信息和浅层沉积物工程地质参数的基础上,从黄河三角洲的实际出发,运用数学地质中的蒙特卡洛方法,结合太沙基一维固结理论,按照黄河三角洲不同叶瓣的沉积厚度和起止时间,对整个三角洲平原的固结压实速率进行了模拟,按照时间序列生成了黄河三角洲浅层沉积物的压实速率等值线图。然后借助地理信息系统(GIS)工具,通过克里格插值(Kriging)的方法得到了黄河三角洲平原地区的数字高程模型(DEM),通过对比压实速率等值线图和数字高程模型,可以对整个黄河三角洲地区压实沉降的时空特征有一个整体的认识。然后根据同样的固结沉降公式对收集的钻孔进行了计算,并同模拟结果对比,结果显示模拟数据与计算结果较为匹配。

此外,针对蒙特卡洛模型中的几种不同的伪随机数发生器进行了讨论,最终通过比较实验选取了最为合适的三种伪随机数发生器。通过实验分析、讨论了不同模型输入参数对于模型输出结果的影响。通过同质(单一属性)地层的模拟对比,发现了影响模拟地层压实沉降速率的主要因素和压实沉降主要贡献土层类型。在权衡模型精度与模拟时间基础上,通过一系列模拟实验,得出了最佳模拟次数。

考虑到黄河三角洲地区广泛分布高含水量高、高压缩性、低抗剪强度和低承载力的软塑至流塑状态的软土,在对黄河三角洲地区的固结压实计算中,考虑了软土层的次固结沉降(蠕变),提出对沉积地层的次固结沉降进行计算,计算结果显示沉积地层的次固结沉降在总固结沉降中占有一定的比重,并不能予以忽略。最后,在以上计算与模拟的基础上,通过与同期InSAR观测和水准测量结果进行对比,定量分离了浅层沉积物固结压实这一自然因素在三角洲地面总沉降量中的份额,为进一步理解黄河三角洲的地面沉降模式提供了新的认识,同时也为应对相对海平面上升、湿地减少、海水入侵和生态资源保护提供技术支撑。

其他摘要

In the past decade, most of the deltas in the world have suffered severe floods, invasions and wetland degradation. The number of people affected has reached 300 million, and the area affected is as high as 260000 km2. A large number of studies have proved that the ground subsidence caused by consolidation and compaction of the lower overlying strata of the delta is the main factor causing the fragility of the delta. Thanks to the advanced technology and complete observation network, such as the phenomenon and influence mechanism of subsidence of the Mississippi Delta ground has been studied and results, restricted by technology and observation equipment, China's Delta subsidence research started late, less data, the method is backward, the low level of research. But, like the the Yellow River Delta this unique River Delta Basin by the shallow sediment, the river changed many times, multi lobe interlacing superposition, the sediment consolidation shows unique characteristics of temporal and spatial variations.

This paper studies the consolidation and compaction characteristics of the delta, which is based on the drilling and section of the past. Based on the extensive collection of drilling information and shallow engineering geological parameters of the Yellow River Delta, this paper starts from the reality of the Yellow River Delta. Based on the Monte Carlo method in mathematical geology and the one-dimensional consolidation theory of the sand foundation, the consolidation compaction rate of the whole delta plain is simulated according to the deposition thickness and the starting and ending time of the different lobes in the Yellow River Delta. Then, by using the Geographic Information System (GIS) tool, the crustal distribution map of the delta plain is obtained by the Kriging method, which has a whole understanding of the temporal and spatial characteristics of compaction settlement in the Yellow River Delta. Finally, the results of compaction compaction calculation are compared with the actual results. The simulation results show that the simulated results agreed well with the actual results.

In addition, several different pseudo-random number generators in the Monte Carlo model are discussed. Finally, the most suitable three pseudo-random number generators are selected by comparison experiments. The influence of different model input parameters on the output of the model is discussed through the experimental analysis. Through the simulation of homogeneous (single attribute) strata, the main factors influencing the compaction settlement rate of the simulated strata and the main types of compaction subsidence are found. On the basis of the accuracy and simulation time of the trade-off model, the best simulation times are obtained through a series of simulation experiments.

Considering the soft soils with high water content, high compressibility, low shear strength and low bearing capacity in the Yellow River Delta, it is considered that the secondary consolidation and compaction (Creep) in the Yellow River Delta is calculated. The results show that the creep of the sedimentary strata occupies a certain proportion in the total consolidation settlements which are expected to exceed 200mm locally. Finally, based on the above calculation and simulation, through comparison with those of the InSAR observations and geodetic measurements, quantitative analysis of shallow sediment consolidation of the natural factors in the share of total settlement in the delta ground, provides a new understanding for the further understanding of the the Yellow River Delta land surface subsidence pattern, and also provide technical support for the response to the relative sea-level rise, wetlands, seawater intrusion and ecological resources protection.

学科领域地球科学 ; 地理学 ; 地质学 ; 海洋科学
学科门类理学 ; 理学::海洋科学 ; 理学::地质学
语种中文
文献类型学位论文
条目标识符http://ir.qdio.ac.cn/handle/337002/154454
专题中国科学院海洋研究所
第一作者单位中国科学院海洋研究所;  海洋地质与环境重点实验室
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张翼. 黄河三角洲浅层沉积物固结压实的时空变化及分布特征[D]. 中国科学院海洋研究所. 中国科学院大学,2018.
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