湿陷性黄土中可回收锚杆锚-土界面抗剪强度随机森林模型  

Random forest model of anchor-soil interfacial shear strength of recoverable anchors in collapsibility loess

作　　者：吕晓玺 陈昌富 张嘉睿[1,2] 蔡焕 陈孝奇 LÜXiaoxi;CHEN Changfu;ZHANG Jiarui;CAI Huan;CHEN Xiaoqi(Key Laboratory of Building Safety and Energy Efficiency(Hunan University),Ministry of Education,Changsha 410082,China;College of Civil Engineering,Hunan University,Changsha 410082,China)

机构地区：[1]建筑安全与节能教育部重点实验室(湖南大学),长沙410082 [2]湖南大学土木工程学院,长沙410082

出　　处：《中国科技论文》2024年第8期884-894,共11页China Sciencepaper

基　　金：国家自然科学基金资助项目(52278349)。

摘　　要：为推进湿陷性黄土地区基坑工程中可回收锚杆的工程应用,以土体含水率(w)、土体干密度(ρ_(d))和锚固体直径(d)作为试验影响因素,开展了湿陷性黄土的湿陷试验以及可回收锚杆微段单元体拉拔试验,获得了黄土湿陷系数(δ_(s))和锚-土界面剪应力-剪切位移曲线随试验影响因素(w、ρ_(d)和d)的变化规律。试验结果表明:湿陷系数随干密度的增大呈减小趋势,随含水率的增大呈减小趋势;锚-土界面峰值剪切强度则随干密度的增大呈增大趋势,随含水率的增大呈减小趋势;单元体试样边界效应与土样软硬程度有关。最后,基于随机森林算法,选取土体含水率、土体干密度、湿陷系数和锚固体直径4个影响因素作为输入变量,建立了湿陷性黄土中可回收锚杆锚-土界面峰值剪切强度预测模型,其训练集和测试集的可决系数(R^(2))分别为0.971、0.915,表明所建立预测模型效果较好。Collapsibility tests of loess and the pullout test of element-scale sample of retrievable anchors were carried out to promote the engineering application of recoverable anchors in the foundation pit project in the area of collapsibility loess.Specifically,the col-lapsibility loess was utilized as soil material in the pullout tests where the water content(w),the dry density of soil(ρ_(d)),and the diameter of anchors(d)were considered as the influential factors.The variation of the collapsibility coefficient of loess(δ_(s))and shear stress-shear displacement curves at the anchors-soil interface with different factors(w,ρ_(d),and d)were obtained.The results show that the collapsibility coefficient decreases with the increase ofρd as well as w.The peak shear strength of the anchor-soil inter-face increases with the rising ofρd,and these values decreases with the elevation of w.Besides,the boundary effect of the element-scale specimen is proved to be related with the plasticity of the soil sample.Finally,a model based on the random forest algorithm is established with w,ρd,δs and d as input variables for the prediction of the peak shear strength of the anchor-soil interface of retriev-able anchor rods in collapsibility loess.The determination coefficients(R^(2))of the training dataset and the test dataset are 0.971 and 0.915,indicating a good performance of the established RF model in anchor-soil interfacial strength forecast.

关 键 词：湿陷性黄土 可回收锚杆 单元体 界面 随机森林 

分 类 号：U455.7[建筑科学—桥梁与隧道工程]