压实黄土场地湿陷沉降机理与黄土高原平山造城适宜性  

Collapse and subsidence mechanism of compacted loess and suitability of mountain bulldozing and city creation projects in the Loess Plateau of China

作　　者：祁生文[1,2,3] 侯晓坤 于永堂 张亚国 胡燮[6] 张琳鑫 李志清 郭松峰[1,2,3] 张帆宇 李同录[8] 彭建兵 Shengwen Qi;Xiaokun Hou;Yongtang Yu;Yaguo Zhang;Xie Hu;Linxin Zhang;Zhiqing Li;Songfeng Guo;Fangyu Zhang;Tonglu Li;Jianbin Peng(Key Laboratory of Shale Gas and Geoengineering,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China;College of Earth and Planetary Sciences,University of Chinese Academy of Sciences,Beijing 100049,China;China Jikan Research Institute of Engineering Investigations and Design,Co.,Ltd.,Xi’an 710043,China;School of Civil Engineering,Chang’an University,Xi’an 710061,China;College of Urban and Environmental Sciences,Peking University,Beijing 100871,China;College of Civil Engineering and Mechanics,Lanzhou University,Lanzhou 730000,China;School of Geological Engineering and Surveying,Chang’an University,Xi’an 710054,China)

机构地区：[1]中国科学院地质与地球物理研究所,中国科学院页岩气与地质工程重点实验室,北京100029 [2]中国科学院地球科学研究院,北京100029 [3]中国科学院大学地球与行星科学学院,北京100049 [4]机械工业勘察设计研究院有限公司,西安710043 [5]长安大学建筑工程学院,西安710061 [6]北京大学城市与环境学院,北京100871 [7]兰州大学土木工程与力学学院,兰州730000 [8]长安大学地质工程与测绘学院,西安710054

出　　处：《科学通报》2023年第14期1844-1860,共17页Chinese Science Bulletin

基　　金：国家自然科学基金(41790442)资助。

摘　　要：黄土高原城市用地紧张与用地需求日益增大的矛盾使得平山造城工程应运而生,大规模平山造城工程会引起场地水文环境变化,诱发填土地基失稳、建筑物破坏等,其工程长期适宜性是人们最关切的问题.通过现场调研、原位监测、室内试验、模型试验、数值模拟和InSAR分析等工作,探究了压实黄土场地湿陷沉降机理及黄土高原平山造城工程适宜性.研究结果发现,场地压实黄土的物理力学性质和微观结构同天然黄土差异较大,其力学性质差、孔隙连通性差、空间变异性大;湿陷变形本质为含水率增大引起土体刚度降低而发生的压密变形,湿陷过程中压实黄土的结构变化整体上表现为颗粒间孔隙的局部压密,颗粒及孔隙形态基本不变;非饱和压实黄土的蠕变特性同屈服应力与上覆荷载的大小密切相关,增大压实土体的干密度可提高屈服应力,缩短蠕变稳定时间,还可显著降低土体的渗透特性;典型平山造城场地厚层压实黄土中的含水状态基本能维持长期稳定,有缓慢的向下水流补给地下水;场地累积变形量随填方土厚度增大而增大,地表变形减缓,沉降速率递减,预测工后15年场地变形可达稳定;增大压实土体干密度和合理设置地下水排水设施可有效减小地表总变形量、变形稳定期和局部破坏.研究结果论证了整体地基的长期稳定性和局部灾害的工程可控性,从理论和实践上证实平山造城工程基本可行,提出了黄土高原平山造城工程的适宜性原则,为未来的平山造城工程提供科学指导.The contradiction between the shortage of urban land and the increasing demand for land in the Loess Plateau brings the emergence of the mountain bulldozing and city creation(MBCC)project.Large-scale hill filling and mountain bulldozing projects will cause changes in the site’s hydrological environment,and induce foundation instability and damage to buildings.The long-term suitability of MBCC projects is the most concerning issue.In this study,field investigations,laboratory experiments,model tests and numerical simulation are utilized to explore the compacted loess’s physical and mechanical behavior,microstructure characteristics,permeability behavior,collapse mechanism,humidification,and creep deformation.In addition,the water migration in thick compacted loess,macroscopic deformation and local failure patterns of a typical MBCC site are investigated using field monitoring,numerical modelling and InSAR analysis.The feasibility and suitability of the MBCC project in the Loess Plateau of China are discussed.It is found that the physical and mechanical properties and the microstructure of compacted loess are quite different from those of natural loess.The compacted loess has low stiffness,large spatial variability,poor pore connectivity and low dominant pore density in comparison to natural loess.The unsaturated permeability parameters(i.e.,soil water characteristic curve and hydraulic conductivity function)are highly related to the soil’s pore size distribution on the microscale and the soil’s dry density on the macroscale.Collapse deformation is inherently compaction deformation due to decreased soil stiffness when the water content increases.It is mainly related to the local compaction of inter-particle pores with the particle and pore morphologies unchanged.The creep characteristics are closely related to the yield stress and overlying load.Increasing the dry density and decreasing the soil water content contribute to increase in yield stress,decrease in creep stabilization time,and reduction in hydrau

关 键 词：黄土高原 平山造城 水分迁移 湿陷机理 沉降规律 

分 类 号：TU444[建筑科学—岩土工程]