沣渭新区超高层建筑CFG桩复合地基计算参数优化

发布时间：2018-01-05 23:13

本文关键词：沣渭新区超高层建筑CFG桩复合地基计算参数优化　出处：《西安科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：近年来西安市为解决大量外来人口住房问题,高层-超高层建筑得到了迅速发展,CFG桩复合地基作为一种节约型地基被广泛使用,但由于CFG桩的设计依据——《建筑地基基础设计规范》(GB5007-2011)和《建筑地基处理技术规范》(JGJ79-2012),两本《规范》均为全国通用,未考虑局部地区的特殊性,因此,在一定区域内对两本规范的CFG桩复合地基计算参数进行优化显得十分必要。西安沣渭新区位于渭河一级阶地,全区范围内未分布有适合作为高层-超高层建筑的天然地基,但依照现行CFG桩设计标准进行深度修正,理论上采用天然地基可行,此外,现行《建筑地基基础设计规范》(GB5007-2011)的计算参数取值范围在该区并不十分适宜,因此,对两本《规范》的计算参数λ、β、ηb进行修正,对不同桩径、桩长、桩距条件下的CFG桩复合地基的桩间土发挥系数β的变化规律进行研究具有现实意义。本文利用公式计算法对CFG桩强度进行了估算;利用数理统计方法对研究区A、B、C三个场地的桩基检测结果进行了分析,研究了计算参数λ、β的显著性;通过检测结果与估算结果的对比分析,得出了最大影响参数的合理取值,并用场地D的检测结果进行了验证。通过对研究区CFG桩深度修正系数ηb的计算分析,得出了CFG桩复合地基的深度修正系数ηb最合理的取值方法,并与场地A的检测结果进行了对比;通过数值模拟,取得了分级加载条件下,研究区内CFG桩桩体、复合地基、桩间土三者的承载力值及变形结果,通过了场地A的原位检测结果检验,进而找到了不同条件下的CFG桩复合地基的桩间土发挥系数β的变化规律。主要研究成果:(1)本文以A、B、C三个场地作为研究对象,通过公式计算,得出CFG桩单桩承载力估算值及计算参数λ、β;通过检测值计算所得计算参数与计算参数比较,以及将检测值带入场地D的CFG桩复合地基单桩承载力检测试验验证,得出研究区计算参数最优为λ=1.0、β=0.8。(2)通过对三种方案修正后的地基承载力结果产生的经济效益进行比较,得出CFG桩复合地基的深度修正系数ηb最合理的取值的方法是:“通过工程地质资料,查明场地内最软弱层的地层情况。通过查《规范》复合地基承载力深度修正系数表,得到最优深度修正系数”。(3)通过对不同设计参数(桩长、桩距、桩径)CFG桩复合地基桩间土的承载力发挥系数计算结果分析,得到不同条件下的CFG桩复合地基的桩间土发挥系数β具有随着桩距的开始阶段增加较快而后期增加缓慢,随着桩径、桩长的增加呈线性显著减小的规律。
[Abstract]:Xi'an city in recent years to solve a lot of housing problems of migrant population, high-rise high-rise building has been developing rapidly, and widely used CFG pile composite foundation as an economical foundation, but because of the design on the basis of CFG pile - < code for design of building foundation (GB5007-2011) > and < > technical code for ground treatment of buildings (JGJ79-2012). Two this is the national general specification > >, without considering the particularity of the local area, so the parameters of the two canonical CFG pile composite foundation in a certain area of optimization is very necessary. Wei Feng Xi'an district is located in Weihe terrace, the region is not suitable for distribution as natural foundation of high-rise high-rise the building, but in accordance with the existing design standards for CFG pile depth correction theory, the natural foundation is feasible, in addition, the code for design of building foundation (GB5007-2011 < >) the calculation parameters The range in this area is not very suitable, therefore, of the two standard parameters > < lambda, beta, ETA B correction of different pile diameter, pile length, pile spacing of CFG pile composite foundation under the condition of the soil between piles variation coefficient play study is of practical significance. This paper uses type calculation method to estimate the CFG pile strength; using the methods of mathematical statistics in the research area of A, B, C foundation of three field test results are analyzed and studied the calculation parameter, significant beta; by comparing the test results with the estimation results, the reasonable value of the largest impact parameters and, with D site detection results were verified. Through the analysis of the study area CFG pile depth correction coefficient calculation of B, the CFG pile composite foundation depth correction coefficient b the most reasonable value method, and the results were compared with the site A; numerical simulation, Made under step load, the study area of CFG pile, composite foundation, pile soil between the three bearing capacity and deformation results by in situ test results of the A test site, and then find out the variation of CFG pile composite foundation under different conditions of the pile soil coefficient of main research. Results: (1) based on the A, B, C three sites as the research object, through the formula, the CFG pile bearing capacity estimation and calculation of parameter values, the calculated beta; calculation parameters and calculation parameters by comparing the detection value, and the detected value into the site of D CFG single pile composite foundation the bearing capacity of pile test verification, calculation parameters for optimal lambda =1.0 research area that beta =0.8. (2) based on the three kinds of results of bearing capacity of the modified project foundation of economic benefit, the value system that depth modification of CFG pile composite foundation is the most reasonable number B The method is: "through the engineering geological data, identify venues within most weak strata. By checking the depth correction coefficient table of bearing capacity of composite foundation" specification >, the optimal depth correction coefficient ". (3) according to the different design parameters (pile length, pile spacing, pile diameter) play capacity coefficient CFG pile composite foundation soil calculation result analysis, get the CFG pile composite foundation under different conditions of soil between piles with pile spacing coefficient has increased rapidly and the late stage began to increase slowly, with the diameter of the pile, the pile length increases linearly decreases significantly.

【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU470

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