Analytical Analysis of Influence of Dewatering on Adjacent Pipelines Based on Pasternak Foundation

doi:10.16183/j.cnki.jsjtu.2020.007

Abstract

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

CLC Number:

TU46+3

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