大型LNG储罐群桩水平承载力确定方法  

Determination method for horizontal load-bearing capacity of pile group for large LNGtank

作　　者：魏成国[1] 王汉文[1] 刘文涛[1] 崔炜[1] 詹旺宇 WEI Chengguo;WANG Hanwen;LIU Wentao;CUI Wei;ZHAN Wangyu(China Petroleum Pipeline Engineering Corporation)

机构地区：[1]中国石油天然气管道工程有限公司,河北省廊坊市065000

出　　处：《油气储运》2024年第9期1056-1063,共8页Oil & Gas Storage and Transportation

摘　　要：【目的】对于大型LNG储罐的群桩基础而言,在OBE(50年超越概率10%)、SSE(50年超越概率2%)两种地震工况下承受的水平力较大,桩水平承载力验算尤为关键。规范经验公式在验算桩水平承载力中存在未考虑群桩中不同位置处桩间土相互叠加影响效应、计算结果偏保守、桩基投资浪费较大的问题。【方法】基于岩土分析软件PLAXIS3D,结合已有现场试桩数据验证土层参数取值的准确性,并对20×10*m大型LNG储罐高桩承台基础进行不同地震荷载作用下的数值模拟计算,得到不同工况下群桩的水平力分布特点。【结果】受力方向前排基桩的水平力值均大于中心基桩,且随水平荷载增大,两者比值呈下降趋势。传统规范设计方法未考虑群桩中不同位置处桩间土相互叠加影响效应,结果偏保守,将造成较大投资浪费。在此基础上,提出一种基于单桩水平承载力试验的LNG储罐群桩水平承载力的确定方法,并与传统规范设计方法进行对比。【结论】该方法在考虑桩根数、桩间距、桩径、桩顶约束方式的同时,通过选用合理的土体本构模型与土层参数,可考虑实际桩间土相互影响,在保证群桩具有足够水平承载力的前提下显著降低设计中的保守度,对提高LNG储罐高桩承台基础设计的经济性具有借鉴作用。(图11,表6,参20)[Objective]The pile group foundation for large LNG tanks is subjected to relatively large horizontal forces under two seismic conditions:Operating Basis Earthquake(OBE)signifying a 10%probability of exceedance within a 50-year period and Safe Shutdown Earthquake(SSE)denoting a 2%probability of exceedance within the same timeframe.Hence,the checking calculation for the horizontal load-bearing capacity of piles is particularly critical.Nevertheless,the existing empirical formulas given in pertinent codes lack accounting for the superposition effect of pile-soil interactions at different positions within pile groups.As a result,these formulas yield conservative results in the checking calculations,potentially leading to inefficient investments in pile foundation construction.[Methods]To address this shortcoming,this study conducted accuracy verification of soil layer parameters through geotechnical analysis software,PLAXIS 3D,by integrating existing data from field experiments.Numerical simulations were carried out to analyze the elevated pile cap foundation for 20x10*m'large LNG tanks under varying seismic loads,obtaining the horizontal force distribution characteristics of pile groups under different conditions.[Results]The study revealed that the front-row piles in the force direction experienced greater horizontal forces compared to the center pile,with their ratio decreasing as horizontal loads increased.Traditional design methods outlined in relevant codes yield conservative results due to disregarding the superposition effect of pile-soil interactions at various positions within pile groups,potentially resulting in significant financial waste.To tackle this challenge,a method to determine the horizontal load-bearing capacity of pile groups for LNG tanks was introduced.This method,based on horizontal load-bearing capacity experiments on individual piles,was subsequently compared with traditional design methods.[Conclusion]In addition to factors like the numbers of piles,pile spacings,pile diameters,and constra

关 键 词：LNG 储罐 群桩承台 数值模拟 受力分析 

分 类 号：TE42[石油与天然气工程—油气田开发工程]