爆炸挤淤置换法筑堤沉降的有限元分析

利用室内试验获得的模型参数结合有限元计算,对深厚淤泥质软基处理建成后的海堤短期和长期沉降问题开展了计算分析。对抛石填料和地基土分别采用莫尔-库伦模型和修正剑桥模型,在地应力平衡的基础上,实施抛石堆载,堆载完成后,开展了工后10年的沉降分析。分析表明,抛石体堆载后,地基土地应力急剧增加,海堤两侧土体向上隆起,下部土体沉降;海堤建成后的621.2天累计沉降达1.2m,孔隙水压仍未消散;建成10年后,海堤累计沉降达1.55m;表明海堤建成后的短期和长期沉降均较大,对重大海堤工程,工后的沉降研究与控制显得必要。     

深厚淤泥控制加载爆炸挤淤处理质量综合检验研究

首先分析了深厚淤泥爆炸挤淤围堤施工中的问题,然后评价目前已有的挤淤质量检验方法,提出了自沉沉降监测法,最后综合利用各种检验方法对一工程进行检验。通过研究发现,体积平衡法简单易行;钻探检测法是最直观最可靠的方法,但花费较高;物探检测法效率高,需结合钻探检测法实施,但在海水中不宜采用;自沉沉降监测法是一种间接方法,实施简单,花费较低。钻探检测法发现本工程围堤除少数标段泥石混合层厚度超过2.5m外,多数标段的挤淤质量良好。     

爆炸排淤填石法机理研究

结合模型实验和数值计算 ,分析了爆炸排淤填石法的机理。在模型实验中 ,通过示踪法建立泥石置换的整体物理图像 ,进而阐述爆炸排淤填石法的机理 ;利用LS DYNA动态有限元分析软件 ,针对爆炸排淤填石过程进行了数值仿真 ,并与实验结果进行了对比。     

爆破挤淤堤坝工后沉降特性离心模拟试验研究

爆破挤淤技术在海洋围垦工程建设中发挥着重要作用,但其理论研究落后于工程实践。通过离心机点火装置的研制实现离心场中的起爆控制,进而建立概化模型,模拟堆石堤坝存在时爆破挤淤的作用效果,研究爆炸荷载作用下地基土体的孔压消散特性及形成堆石堤坝的工后沉降特性。通过多次尝试性试验,最终取得两组合理有效的爆破试验测试成果。研究表明:地基土含水率越高、强度越低,爆破后堤坝瞬时沉降越大,爆破挤淤置换效果也更显著;在地基土较软弱的条件下,爆破挤淤堤坝工后沉降明显较大;在堤坝上覆压力存在的条件下,爆破瞬间地基土中产生显著的超孔隙水压力,超孔压的产生使得地基土瞬时有效抗剪强度弱化,甚至会丧失结构强度和承载能力,从而为爆破挤淤"泥–石"置换过程创造了有利条件。     

控制加载爆炸挤淤施工技术在护岸工程中的应用

结合宁德核电厂东护岸工程实践介绍了利用控制加载爆炸挤淤置换法进行设计与施工的情况,工程实践表明,该方法是合理可靠的,其在工程质量、进度要求、安全与成本控制上能够满足相关技术标准的要求。     

抛土（石）挤淤法挤淤效果探讨

抛土挤淤法挤淤效果是工程界采用该方法时所关心的问题，本文采用验算地基极限承载力的方法对此问题进行探讨。     

爆炸挤淤法处理地基爆淤参数确定

通过同一地区爆炸挤淤施工时,不同爆炸挤淤控制参数施工的堤体坡脚钻孔探摸检测,分析了不同施工工艺下,爆炸挤淤法施工的块石落底深度、混合层厚度、下卧持力层等设计控制要素的状态,得出了单纯按照水深折减计算的爆炸挤淤参数略小,而采用加大炸药包的埋置深度,同时适当加大布药孔数的方式,能够较好的提高爆炸挤淤法处理的施工质量,值得推广应用。     

爆炸挤淤法在软基处理中的应用

爆炸挤淤处理软基已得到广泛应用,并取得了较好的效益。以下通过实际工程中技术问题的解决、施工工艺及爆炸参数的确定,结合质量检测等方面论证了该方法在工程中的成功应用。     

关于填土（石）挤淤工法的探讨

介绍填土（石）挤淤法在层厚超过20m的淤泥条件下的挤淤效果,并用验算地基稳定的方法从理论上解释和预测深厚淤泥的挤淤置换,提出了若干提高挤淤效果的措施。     

海湾浅滩控制性爆破挤淤填石路基施工技术

针对海湾浅滩路基施工进行分析,讨论了海湾浅滩控制性爆破挤淤填石路基的施工工艺及施工要点控制。     

基于Excel沉降观测内业计算与异常数据处理

文章介绍了建筑物沉降观测的施测特点,以及应用微机电子表格Excel进行内业数据计算的方法,并对沉降观测中的异常数据情况作了一定的分析以及提出一些处理方法。     

两种单桩沉降计算方法的比较分析

就单桩沉降计算方法——Geddes法和剪切位移传递法的原理、模型建立、参数选用进行了介绍,经对比分析得出如下结论:剪切位移传递法相对Geddes法而言,具有求解范围更广、参数易确定、接近桩的实际工况、能较好的反映荷载传递情况等优势,但因其计算模型没有考虑土的连续性,在推广到群桩基础时,无法较好反映实际工况;而Geddes法建立在弹性理论基础上,虽能较好地被推广到群桩基础的分析中,但对桩的刚性有较高要求,适用范围有限。本文的分析有助于我们根据实际情况选择适宜的计算方法。     

Effectiveness of CFG pile-slab structure on soft soil for supporting high-speed railway embankment

The use of cement-fly ash-gravel (CFG) pile-slab structures is a new effective technique for reducing the settlements of soft foundations in China. A comprehensive research was conducted to investigate the effectiveness of a CFG pile-slab structure-supported embankment of the Beijing-Shanghai high-speed railway in China. Firstly, an analytical method was formulated to calculate the settlements of the CFG pile-slab structure-supported embankment. Secondly, mechanical scaling laws were derived for the proposed testing plan at model scale. Model tests were conducted to quantify and to interpret the settlement distributions. Thirdly, the influence of three key factors (pile length, pile diameter, and slab thickness) for the structural form of the CFG pile-slab structure-supported embankment on the settlement distribution were studied using numerical simulations. The maximum settlements of the CFG pile-slab structure-supported embankment in optimizing the structural form were obtained using the above three research methods and then they were compared with each other. The results show that (1) the settlements obtained by the analytical method, the physical model tests, and the numerical simulations showed good concordance with each other; (2) the settlement-controlling effect of the CFG pile-slab structure was able to meet the requirements of high-speed railway construction; (3) the piles and the soil-bearing capacities of the CFG pile-slab structure-supporting embankment could be fully mobilized because of the “load re-distribution” function of the slab; and (4) the affected area of the engineering load had a depth of more than 18.75?m and a horizontal length of 7.5?m near the toe of the embankment slope.     

A simplified method for prediction of embankment settlement in clays

The prediction of embankment settlement is a critically important issue for the serviceability of subgrade projects,especially the post-construction settlement.A number of methods have been proposed to predict embankment settlement;however,all of these methods are based on a parameter,i.e.the initial time point.The difference of the initial time point determined by different designers can de?nitely induce errors in prediction of embankment settlement.This paper proposed a concept named"potential settlement"and a simpli?ed method based on the in situ data.The key parameter"b"in the proposed method was veri?ed using theoretical method and?eld data.Finally,an example was used to demonstrate the advantages of the proposed method by comparing with other methods and the observation data.     

A simplified method for prediction of embankment settlement in clays简

The prediction of embankment settlement is a critically important issue for the serviceability of subgrade projects, especially the post-construction settlement. A number of methods have been proposed to predict embankment settlement; however, all of these methods are based on a parameter, i.e. the initial time point. The difference of the initial time point determined by different designers can definitely induce errors in prediction of embankment settlement. This paper proposed a concept named “potential settlement” and a simplified method based on the in situ data. The key parameter “b” in the proposed method was verified using theoretical method and field data. Finally, an example was used to demonstrate the advantages of the proposed method by comparing with other methods and the observation data.     

路堤下钉形搅拌桩复合地基沉降计算方法——广义桩体法

针对钉形搅拌桩这种变截面搅拌桩,通过一定的假设,将其简化为上、下直径相等而模量不等的常规等截面桩,提出了钉形搅拌桩复合地基沉降计算方法--广义桩体法。根据位移、应力连续条件,将路堤填土、加固区和下卧层作为统一的整体,提出了考虑桩顶上刺、桩土相互作用和桩端下刺的加固区计算模型,并建立了模型的有限差分解法。基于三维数值模拟结果,提出考虑路堤下钉形搅拌桩复合地基下卧层应力集中的附加应力计算方法,从而建立路堤荷载下钉形搅拌桩复合地基的沉降计算方法。计算实例表明:复合模量法计算结果偏小,而应力修正法偏大,本文方法最接近实测结果,说明其具有一定的适用性。     

地基沉降计算分析

简述了地基沉降量的含义,分析了地基沉降计算的三种方法,即分层总和法、弹性力学公式、建筑地基基础设计规范推荐的方法,指出在学习地基沉降计算时,重要的是要掌握地基产生沉降的原理、各种计算方法的适用范围及计算参数的测定和选用。     

垃圾填埋场沉降计算方法及原理

介绍了国内外已有的填埋场沉降计算模型,包括传统土力学基础上发展起来的计算模型、经验公式、流变模型、考虑降解的综合性模型,对各种计算方法的优缺点进行了评述,提出了考虑降解和分级堆填影响的重要性。     

垃圾填埋场沉降计算研究

为了保证垃圾填埋场的安全可靠,分别利用传统的土力学方法和有限元的计算方法对填埋场沉降进行了计算,并比较了这两种方法的计算结果,得出传统方法计算结果比有限元计算结果稍大的结论。