西安市区黄土湿陷特性研究  

Self-weight collapsible characteristics of loess in Xi'an urban area

作　　者：康佐 亢佳伟 邓国华[2,3] 郑建国 王丽琴 高虎艳[1] KANG Zuo;KANG Jiawei;DENG Guohua;ZHENG Jianguo;WANG Liqin;GAO Huyan(Xi'an Rail Transit Group Co.,Ltd.,Xi'an 710018,China;Xi'an University of Technology,Xi'an 710048,China;Xi'an Loess Underground Engineering Technology Consulting Co.,Ltd.,Xi'an 710000,China;China Jikan Research Institute of Engineering Investigations and Design Co.,Ltd.,Xi'an 710043,China)

机构地区：[1]西安市轨道交通集团有限公司,陕西西安710018 [2]西安理工大学,陕西西安710048 [3]西安黄土地下工程技术咨询有限公司,陕西西安710000 [4]机械工业勘察设计研究院有限公司,陕西西安710043

出　　处：《岩土工程学报》2025年第5期914-925,共12页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金面上项目(52178355);陕西省自然科学基础研究计划资助项目(2022JM-216)。

摘　　要：基于西安市轨道交通工程建设过程中开展的12组黄土大型试坑浸水试验和室内湿陷试验,系统研究了西安市区黄土的湿陷特征。研究表明:①西安市区范围内,各地貌单元的湿陷性由强到弱依次为渭北黄土塬>浐河三级阶地>塬前洪积台塬>黄土梁洼﹥少陵塬(杜陵塬、神禾塬)、渭河三级阶地。自重湿陷性黄土场地占试验场地总数的50%,自重湿陷最大下限深度20 m;市区南部黄土塬均为非自重场地,与以往室内试验认识不同;②自重湿陷变形主要发生在Q3黄土地层中,现场试验实测得到自重湿陷底界多位于Q3古土壤层,仅2组试验中的Q2黄土表现出弱湿陷性。现行规范中提供的关中地区统一的修正系数高估了Q2黄土的湿陷量。③区分地貌单元和地层沉积时代,给出了修正系数建议值;④浸水湿陷的平面影响范围与自重湿陷深度和湿陷量相关,一般不超过1倍的试坑半径和1倍的实测自重湿陷深度,可作为工程周边浸水设防边界;⑤黄土湿陷变形发展过程主要包括快速下沉、缓慢下沉、下沉稳定、停水后快速下沉和停水后下沉稳定5个阶段。实测自重湿陷量越大,下沉阶段单日沉降速率越大。停水后固结沉降量最大可达95.1 mm。Based on the results of 12 large test pit immersion tests of loess and indoor collapsibility tests conducted during the construction process of Xi'an Rail Transit project,the self-weight collapsible deformation characteristics of loess in Xi'an urban area are systematically studied.The results show that:(1)Within the urban area of Xi'an,the collapse of each landform unit,from strong to weak,is in the following order:Weibei Loess Plateau>Chanhe Tertiary Terrace>pluvial tableland>loess ridge and depressiona>Shaoling Plateau(Duling Plateau,Shenhe Plateau),and Weihe Tertiary Terrace.The self-weight collapsible loess site accounts for 50%of the total number of test sites,and the maximum depth of the self-weight collapsible bottom limit is 20 m.The loess plateau in the southern part of the city is a non self-weight collapsible site.(2)The deformation of the self-weight collapse occurs mainly in the Q3 loess layer.Based on the immersion tests,the bottom boundary of self-weight collapse is mostly located in the Q3 ancient soil layer.Only Q2 losses in two sets of tests exhibit weak collapse.The uniform correction coefficient provided in the current regulations for the Guanzhong region overestimates the collapsibility of Q2 losses.(3)Distinguishing between geomorphic units and sedimentary ages of strata,the recommended values for the self-weight collapsible deformation correction coefficients of loess in Xi'an urban area are provided.(4)The measured area of settlement diffusion due to loess immersion and collapse is typically related to the depth and amount of self-weight collapse.It usually does not exceed 1.0 times the radius of the test pit and 1 times the measured collapsible limit depth.This can serve as a boundary for water accumulation around the project.(5)The development process of collapsible deformation of loess mainly includes five stages:rapid deformation,slow deformation,stable deformation,rapid deformation after water interruption,and stable deformation after water interruption.The larger the measured self-w

关 键 词：黄土 自重湿陷变形特征 浸水试验 变形修正系数 地貌类型 沉积时代 

分 类 号：TU411[建筑科学—岩土工程]