摘要
【目的】随着基坑开挖深度的不断增大和基坑周边环境的严格要求,内支撑支护体系逐渐成为基坑支护的主要型式。因此,针对多层对撑式内支撑考虑位移土压力和施工过程的计算理论的研究很有必要。【方法】首先,对宰-梅位移土压力模型进行了改进,采用复合曲线拟合位移与土压力的关系,推导出基于位移的土压力计算公式。然后,根据支护桩节点的弯矩和剪力静力平衡条件,提出一种全新的建立排桩杆系有限单元法总刚度矩阵的简易计算方法,该方法可以将两侧排桩一并进行计算。最后,依托工程实例,对考虑位移土压力和施工过程与《建筑基坑支护技术规程》(JGJ 120—2012)(以下简称《规程》)推荐的朗肯主动土压力和不考虑施工过程计算的桩身弯矩和剪力的差异性进行了对比。【结果】结果显示:算例中《规程》推荐的朗肯主动土压力比文中的位移土压力荷载小16%~32%左右,并且通过工程实例加以验证,其中《规程》计算方法比监测数据最大弯矩小10%,最大位移小14%。文中方法比监测数据最大弯矩大4%,最大位移大6%。【结论】结果表明:两种方法存在较大的差异,应引起重视。对于对撑式支护桩结构,当两侧地质条件相近时两侧支护桩向坑内发生位移,这种位移主要是靠支撑梁的压缩变形产生的,其位移很小,所以作用在支护桩上的土压力荷载更接近于静止土压力而不是《规程》中的主动土压力,所以产生本文计算算例的结果,更是情理之中的事情。该方法适用于任意层的对撑支护体系的计算与分析。
[Objective]With the increase in excavation depth of foundation pit and the strict requirements of surrounding environment of foundation pit,the internal support system is gradually becoming the most main support form of foundation pits.Therefore the calculation theory of multi-layer opposite supports considering displacement earth pressure and construction process is studied.[Methods]Firstly,the displacement earth pressure model proposed by Zai-Mei is improved,and a composite curve is adopted to fit to the relationship between the displacement with earth pressure,and the displacement earth pressure formula is derived.Secondly,a new simple calculation method for establishing the total stiffness matrix of the finite unit method of the row piles rod system is proposed based on the bending moment and shear force static equilibrium conditions of the nodes.The method proposed can calculate the bilateral row piles together.Finally relying on engineering examples,the differences between the pile bending moment and shear force calculated by considering the displacement earth pressure and construction process with no considering the displacement earth pressure and construction process given in the Regulations are analyzed.[Results]The results show that the Rankine active earth pressure recommended by the Regulation in the calculation examples of this paper is about 16%to 32%smaller than the displacement earth pressure load of this paper,and it is verified by engineering examples,in which the calculation method of the Regulation is 10%smaller than the maximum bending moment of the monitoring data,and the maximum displacement is 14%smaller than that of the monitoring data.The method of this paper is 4%larger than the maximum bending moment and 6%larger than the maximum displacement of the monitoring data.[Conclusion]The results show that there are large differences between the two method,which should be emphasized.For the buttress type supporting pile structure,when both sides of the geological conditions are similar to both sides of the supporting pile to the pit displacement,this displacement is mainly by the compression deformation of the support beams,the displacement is very small,so the earth pressure load acting on the supporting pile is closer to the static earth pressure rather than the norms of the active earth pressure,so it is more than reasonable to produce the result of this paper′s calculations examples.This method is applicable to the calculation and analysis of any layer of the support system.
作者
刘红谷
孙勇
金亚兵
阮升
LIU Honggu;SUN Yong;JIN Yabing;RUAN Sheng(Key Laboratory of Karst Georesources and Environment,Ministry of Education,Guizhou University,Guiyang 550025,Guizhou,China;College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,Guizhou,China;Shenzhen Geology Bureau,Shenzhen 518023,Guangdong,China;China Construction Eighth Engineering Bureau Huazhong Construction Co.,Ltd.,Wuhan 430021,Hubei,China)
出处
《水利水电技术(中英文)》
北大核心
2024年第11期165-175,共11页
Water Resources and Hydropower Engineering
基金
国家自然科学基金项目(51168009)
广东省深圳市地质局地质工程院士工作站专项经费资助项目(2013B090400025)。
关键词
深基坑开挖
对撑支护
支护桩
位移土压力
施工过程
有限杆单元法
数值模拟
excavation depth of foundation pit
opposite support
supporting pile
displacement earth pressure
construction process
finite rod
numerical simulation
