大厚度非连续湿陷性黄土浸水变形特征分析  

Analysis of soaking deformation characteristics of large-thickness discontinuous collapsible loess

作　　者：刘建磊 卫童瑶 惠寒斌 姜耀飞 LIU Jianlei;WEI Tongyao;HUI Hanbin;JIANG Yaofei(Yellow River Engineering Consulting Co.,Ltd.,Zhengzhou 450003,Henan,China)

机构地区：[1]黄河勘测规划设计研究院有限公司,河南郑州450003

出　　处：《地质力学学报》2024年第6期921-932,共12页Journal of Geomechanics

基　　金：中国博士后面上基金项目(2021M691186)。

摘　　要：非连续分布的黄土地层在中国关中平原地区广泛分布,由于其特殊的地层结构,在评价地基湿陷性时自重湿陷量的室内计算值与现场实测值有较大的差异。为此,文章以关中盆地渭河北岸黄土塬地层为研究对象,开展了室内湿陷性试验和现场大型试坑浸水试验,对比了现场与室内湿陷量差异的影响因素。同时在结合数值计算的基础上,分析了现场浸水试验的渗流特征。研究结果显示:场地现场试验和室内试验的自重湿陷量比值小于0.1,产生此差异的原因包括黄土地层的非连续性和不均匀性、室内试验的取样扰动因素以及现场试验的浸水条件差异;黄土的非连续性形成的层拱效应是造成室内试验与现场试验差异的主要原因,其削弱了部分向上传递的变形、阻碍了向下传递的自重应力,同时造成渗流过程的不连续;计算自重湿陷量时,可采用根据地层时代分层的计算方法,该方法可为该地区未来的工程建设提供理论指导。[Objective]The unique stratigraphic structure of the widely distributed discontinuous loess stratum in the Guanzhong Plain area of China results in significant differences between the indoor calculated values and field-measured values of the self-weight wetting amount for evaluating the foundation’s wetting property.[Methods]Indoor wetting tests and large-scale test pit immersion tests were carried out on-site to compare the factors influencing the difference between on-site and indoor wetting amounts,with the loess stratum on the north bank of the Weihe River as the research object.[Results]The following results were obtained from the study:(1)The ratio of self-weight wet depressions between field and indoor test was less than 0.1.This discrepancy was due to the discontinuity and inhomogeneity of loess layers,sampling disturbances in indoor tests,and differing immersion conditions in field test.(2)The“layer bow effect”caused by the discontinuity of loess was the main reason for the difference between the indoor and field tests.This effect weakened upward-transmitted deformation,hindered downward-transmitted gravity stress,and caused discontinuity in the percolation process.(3)Stratification calculations for the four test sites showed that most of the gravitational self-wetting in the field tests occurred in the Qp^(3)soil layer,while the Qp^(2)loess layer showed large difference between the field-measured and indoor test values.Thus,the Qp^(2)loess layer has little to no wetting effect.[Conclusion]The shape of the saturated zone range obtained through numerical simulation was consistent with the field test results,and the numerical simulation method was more advantageous for observing the experimental results.When calculating wet subsidence by self-weight,a stratification method based on the strata age can be used.For the Qp^(3)stratum,the correction coefficient method specified in the guidelines was chosen,while the Qp^(2)loess stratum was determined by an on-site pit immersion test.[Significance]The rese

关 键 词：湿陷性黄土 现场浸水试验 湿陷变形特征 黄土-古土壤 

分 类 号：TU444[建筑科学—岩土工程] P642.131[建筑科学—土工工程]