考虑欠固结因素的坝前淤积土一维固结分析  

Analysis of one‑dimensional consolidation behavior of sediment in front of dam considering underconsolidation factors

作　　者：张志龙 王红雨[1] 陆通 王韵 常留成 ZHANG Zhilong;WANG Hongyu;LU Tong;WANG Yun;CHANG Liucheng(School of Civil and Hydraulic Engineering,Ningxia University,Yinchuan 750021,China;Ningxia Water Conservancy and Hydropower Engineering Bureau Co.,Ltd.,Yinchuan 750004,China)

机构地区：[1]宁夏大学土木与水利工程学院,宁夏银川750021 [2]宁夏水利水电工程局有限公司,宁夏银川750004

出　　处：《武汉大学学报（工学版）》2023年第7期781-790,共10页Engineering Journal of Wuhan University

基　　金：国家自然科学基金项目(编号:41962016);宁夏回族自治区重点研发项目(编号:2018BFH03010);宁夏大学研究生创新项目(编号:GIP202069)。

摘　　要：“坝前淤积面加坝”是宁夏南部黄土丘陵山区水库除险加固工程中普遍采用的一种施工方法。考虑到当地水库运行特点,可将坝前淤积层视为近似于静水中沉积,土层内存在尚未完全消散的超静孔隙水压力,处于欠固结状态。如何确定欠固结淤积土在堆载固结施工前土层内部的状态是坝前淤积层加坝需要解决的关键问题。基于大变形固结理论的分段线性方法编写了用于计算淤积土晾晒间自重固结的计算程序,利用文献中的相关算例进行了验证,提出了针对欠固结土的固结计算模式,并分析讨论了影响欠固结淤积土固结的主要因素。选取西北地区坝前淤泥面加坝工程案例,通过与其他计算方法的对比分析,探究了考虑欠固结因素对淤积土排水固结计算的影响程度。结果表明:欠固结淤积土在晾晒期间其体内孔隙比、超静孔压随深度呈非线性变化,底部固结速度、单位厚度压缩量相对较大;土层初始高度和初始孔隙比对欠固结淤积土沉降结果影响显著;如果将欠固结土按正常固结土计算,沉降量会被低估。The construction method of“adding new dam body to the silt surface in front of dam”is commonly used in the reservoir reinforcement engineering of loess hilly region in southern Ningxia.Considering the operating characteristics of the local reservoirs,the sedimentation layer in front of the dam is regarded as similar to the static water deposition,and there is an excess pore water pressure in the soil layer that has not been completely dissipated,and it is in a state of under-consolidation.How to determine the state of underconsolidated silt in the soil layer before the construction of pile consolidation is the key problem to be solved.Based on the piecewise linear method of large deformation consolidation theory,a calculation program for calculating the gravity consolidation of the sediment during the drying period was compiled,which was verified by the relevant calculation examples in the literature.The consolidation calculation model for the underconsolidated soil was proposed and the main factors affecting the consolidation of under-consolidated sediment were analyzed and discussed.The case of“adding new dam body to the silt surface in front of dam”in northwest China was selected to explore the influences of under-consolidation factors on the calculation of drainage consolidation of silted soil through comparative analysis with other calculation methods.The results show that the void ratio and excess pore water pressure of the under-consolidated sediment during the drying period nonlinearly change with the depth,and the bottom consolidation speed and the compression per unit thickness are relatively large.The initial height and the initial void ratio of the soil layer have significant effects on the settlement results of under-consolidated sediment.If under-consolidated soil is calculated as normal consolidated soil,the settlement will be underestimated.

关 键 词：欠固结土 自重固结 大变形 分段线性方法 

分 类 号：TU457[建筑科学—岩土工程]