稳态渗流下非饱和土涵洞竖向土压力的迭代解与简化  

Iterative solutions of vertical earth pressure against culverts in unsaturated soils under steady infiltration and its simplification

作　　者：张常光[1,2] 吴凯 孟祥忠 王晓轮 ZHANG Changguang;WU Kai;MENG Xiangzhong;WANG Xiaolun(School of Civil Engineering,Chang′an University,Xi′an 710061,China;Stake Key Laboratory of Geohazard Prevetion and Geoenvironment Protection(Chengdu University of Technology),Chengdu 610059,China;Norinco Group Testing and Research Institute,Huayin 714200,Shaanxi,China)

机构地区：[1]长安大学建筑工程学院,西安710061 [2]地质灾害防治与地质环境保护国家重点实验室(成都理工大学),成都610059 [3]中国兵器工业试验测试研究院,陕西华阴714200

出　　处：《哈尔滨工业大学学报》2024年第3期68-77,共10页Journal of Harbin Institute of Technology

基　　金：地质灾害防治与地质环境保护国家重点实验室开放基金(SKLGP2020K022);中央高校基本科研业务费专项资金(300102282206)。

摘　　要：为描述稳态渗流下不同类别非饱和土涵洞的竖向土压力变化,应用圆弧小主应力轨迹法和Mohr应力圆获得考虑土拱效应的滑移面土压力系数,继而基于非饱和土的有效应力强度公式与吸应力理论,由水平薄层单元的竖向力平衡分别建立稳态渗流下上埋式/沟埋式非饱和土涵洞竖向土压力的迭代解,给出应用步骤并开展对比验证与方法拓展,最后结合吸应力沿深度分布规律提出涵洞竖向土压力的简化实用公式。研究结果表明:涵洞竖向土压力迭代解能合理反映土体类别、水分蒸发、降雨入渗和土拱效应的综合影响,并得到文献现场实测和理论公式数据的正确性验证以及对非饱和土涵洞的适用性;涵洞竖向土压力实用公式可显式表达且精度良好,方便估算不同稳态渗流下涵洞主要荷载;砂土涵洞可忽略非饱和特性影响而按饱和土计算竖向土压力,粉土和黏土涵洞可简化吸应力沿深度为线性分布;上埋式涵洞土拱负效应使得竖向土压力增大,而沟埋式涵洞土拱正效应使得竖向土压力减小。In order to describe the variation of vertical earth pressure against culverts for different types of unsaturated soils under steady infiltration,the earth pressure coefficient at a sliding surface considering soil arching effect was derived by assuming the minor principal stress trajectory and Mohr stress circle.Based on the effective stress strength equation of unsaturated soils,the suction stress theory,and the vertical force equilibrium of a horizontal thin layer element,this study then respectively presented iterative solutions of vertical earth pressure against positive-buried/trench-buried culverts in unsaturated soils under steady infiltration along with providing application steps.Comparative validations and method extensions were also performed.Finally,simplified practical formulations of vertical earth pressure were introduced according to distribution laws of suction stress with depth.The results show that iterative solutions of vertical earth pressure against culverts can reasonably address comprehensive influences of soil type,water evaporation,rainfall infiltration,and soil arching effect.Moreover,these iterative solutions and their applicability to culverts in unsaturated soils are verified by comparing with the data of field measurements and theoretical calculations reported in the literature.Practical formulations of vertical earth pressure against culverts can be expressed explicitly with high accuracy,and they are readily to be adopted to estimate primary culvert loads under different steady infiltrations.Vertical earth pressure against culverts in sands could be determined as saturated soils due to ignoring the effect of unsaturated characteristics.The suction stress can be simplified as a linear profile with depth for culverts in silts and clays.The negative soil arching effect of a positive-buried culvert increases the vertical earth pressure,whereas the positive soil arching effect of a trench-buried culvert reduces the vertical earth pressure.

关 键 词：涵洞 非饱和土 竖向土压力 稳态渗流 实用公式 

分 类 号：TU432[建筑科学—岩土工程]