Pasternak地基降水对邻近管线影响的解析研究

doi:10.16183/j.cnki.jsjtu.2020.007

摘要/Abstract

摘要：

基于Pasternak弹性地基梁理论,结合土的有效应力原理和Dupuit假设,推导了砂土地层单井降水引起邻近管线变形的解析解.算例解析计算结果与抽水试验及数值模拟结果吻合较好,验证了其准确性,在此基础上深入分析了管线受力变形的影响参数.结果表明:研究管-土相互作用时,土中剪力的影响不应被忽略,管线变形范围与降水影响半径大致相等.降水深度、管线与降水井距离对管线变形及受力有较大影响,且存在临界降深,使得管线变形及受力发生较大转变.到达临界降深前,管线变形和弯矩最大值位于管线中心,随降深增大而增大.超过临界降深后,管线弯矩最大值会随降深增大由管线中心向外偏移,出现两个弯矩峰值,位于水位线与管线相交处.研究成果可为相关工程的管线防护提供参考.

关键词: 单井降水, 地下管线, Pasternak 地基模型, 管线变形, 受力分析

Abstract:

Based on the Pasternak model of elastic foundation beams, and combining the effective stress principle of soil and Dupuit hypothesis, the analytical solution of adjacent pipeline deformation in sandy soil caused by single well dewatering is derived. The example calculation results are in good agreement with the results of pumping test and numerical simulation, which verifies the applicability. The law of stress and deformation for the pipeline is studied by parameter analysis. The results show that the influence of soil shear stiffness should not be ignored in the study of soil-pipeline interaction and the pipeline deformation range is approximately equal to the influence radius of dewatering. Pipeline deformation and stress are greatly influenced by dewatering depth and the distance between the pipeline and the dewatering well. Before reaching the critical drawdown, the maximum value of pipeline deformation and bending moments are at the center of pipeline, increasing with the increase of dewatering depth. When the dewatering depth exceeds the critical drawdown, the maximum bending moment will shift outward from the center with the increase of the dewatering depth, resulting in two peak bending moments which are at the intersection of the water level line and at the pipeline. The research results can provide reference for pipeline protection in relevant projects.

Key words: single well dewatering, underground pipeline, Pasternak foundation model, pipeline deformation, stress analysis

中图分类号:

TU46+3

徐长节, 曾怡婷, 田威, 陈明. Pasternak地基降水对邻近管线影响的解析研究[J]. 上海交通大学学报, 2021, 55(6): 652-662.

XU Changjie, ZENG Yiting, TIAN Wei, CHEN Ming. Analytical Analysis of Influence of Dewatering on Adjacent Pipelines Based on Pasternak Foundation[J]. Journal of Shanghai Jiao Tong University, 2021, 55(6): 652-662.

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地层分类	平均厚度/m	重度/(kN·m^-3)	孔隙比	水平渗透系数/(cm·s^-1)	压缩模量/MPa
①杂填土	5	18.0	0.790	8.00×10^-3	-
②₁砂质粉土	4	18.2	0.815	6.80×10^-4	9.6
②₂细砂	9	18.9	0.782	5.37×10^-3	10.5
②₃粉土夹粉砂	4	18.5	0.735	4.45×10^-3	9.3
②₄粉砂夹粉土	2	18.6	0.724	4.72×10^-3	10.2
③淤泥质粉质黏土	26	18.0	1.121	5.00×10^-9	3.4

土体参数	取值
天然重度/(kN·m^-3)	18
饱和重度/(kN·m^-3)	18.5
渗透系数/(cm·s^-1)	0.005
泊松比	0.3
压缩模量/MPa	10

管线参数	取值
直径/m	1
壁厚/m	0.1
埋深/m	6
距降水井距离/m	10
模量/GPa	30
截面惯性矩/m⁴	0.029