低能强夯真空排水法孔压消散及沉降计算研究

发布时间：2018-05-14 22:24

本文选题：低能强夯法 + 真空压力　；参考：《福建农林大学》2017年硕士论文

【摘要】：强夯法联合塑料排水板地基处理新技术自问世以来,在国内外的工程应用越来越多,与其相关的理论研究也在不断深化。在强夯法联合塑料排水板地基处理技术基础上,为了适应临近建筑物和道路设施,且先行大面积填方的软基处理施工,发展了低能强夯真空排水法,实践表明,该工法具有地基处理效果好、工期短、成本低等优势,应用前景广阔。但目前有关该工法孔压消散及沉降计算的理论及工程应用研究,还有待深入和加强。本文利用前人研究成果,结合工程实例,研究该工法的孔压消散和沉降计算,主要工作及取得成果如下:(1)阐述低能强夯真空排水法的研究现状,进行低能强夯真空排水法与其他传统工法优缺点比较;在已有的强夯与排水固结理论研究基础上,图解分析低能强夯真空排水法加固机理及加固特点,并介绍低能强夯真空排水法的工艺要点和工艺流程。(2)通过孔隙水压力计算值和现场孔压监测数据的分析,研究低能强夯真空排水的孔压消散特性,进一步阐明该工法的加固机理:通过低能强夯形成上硬下软的双层地基,利用真空负压使下卧层与加固层形成压力差,联合竖向塑料排水板使土体中孔隙水快速排出,孔隙水压力消散,土体固结沉降。(3)分不考虑和考虑真空压力两种情况,分别计算孔压消散理论值,经与孔压现场实测值对比表明:考虑真空压力计算的孔压值与实测值更接近、更吻合;孔压消散速度先快后慢,强夯结束后第1天,孔压消散很快,孔压消散度约达40%,之后孔压消散度逐渐减小直至趋于某一限值;土体的再固结体积压缩系数影响孔压消散速度,再固结体积压缩系数越大,孔隙水压力消散得越快;真空管产生的负压具有预压作用,强夯和真空压力的耦合作用能加快孔隙水压力的消散,缩短多遍强夯之间的时间间隔。(4)对低能强夯真空排水法进行沉降分析,基于冲击荷载作用下双层地基的形成机制,推演提出低能强夯真空排水法地基沉降计算公式。将该公式用于案例工程沉降计算,经与现场实测的沉降数据对比,计算值与实测值的偏差为6%～10%,较好满足工程精度要求,可供同类工程应用参考。
[Abstract]:Since the advent of the new technology of dynamic compaction combined with plastic drainage plate foundation treatment, it has been applied more and more in engineering at home and abroad, and the theoretical research related to it has been deepened. On the basis of dynamic compaction combined with plastic drainage board foundation treatment technology, in order to adapt to the construction of adjacent buildings and road facilities, and to advance the soft foundation treatment construction of large area fill, the vacuum drainage method of low energy dynamic compaction is developed. The practice shows that, The method has the advantages of good foundation treatment effect, short construction period, low cost and so on. However, the theoretical and engineering application of the method for pore pressure dissipation and settlement calculation needs to be further developed and strengthened. In this paper, the pore pressure dissipation and settlement calculation of this method are studied with previous research results and engineering examples. The main work and results are as follows: 1) the research status of vacuum drainage method with low energy dynamic compaction is described. The advantages and disadvantages of vacuum drainage method with low energy dynamic compaction and other traditional methods are compared, and on the basis of the existing research on the theory of dynamic compaction and drainage consolidation, the strengthening mechanism and characteristics of vacuum drainage method with low energy dynamic compaction are analyzed graphically. The main process points and technological process of vacuum drainage with low energy dynamic compaction are introduced. Through the analysis of pore water pressure calculation value and field pore pressure monitoring data, the pore pressure dissipation characteristics of vacuum drainage with low energy dynamic compaction are studied. The reinforcement mechanism of this method is further expounded: the double layer foundation is formed by low energy dynamic compaction, the pressure difference between the horizontal layer and the strengthened layer is formed by vacuum negative pressure, and the pore water in the soil is discharged quickly by the combination of vertical plastic drainage plate, Pore water pressure dissipates and soil consolidation settlement. 3) the theoretical value of pore pressure dissipation is calculated separately without considering or considering vacuum pressure. The comparison with the field measured value of pore pressure shows that the pore pressure calculated by considering vacuum pressure is closer to the measured value. The velocity of pore pressure dissipation is faster than that of slow one day after dynamic compaction the pore pressure dissipates quickly and the dissipation degree of pore pressure reaches about 40. After that the dissipation degree of pore pressure decreases gradually until it tends to a certain limit. The coefficient of reconsolidation volume compression affects the velocity of pore pressure dissipation. The larger the coefficient of volume compression of soil is, the faster the pore water pressure dissipates, and the negative pressure produced by vacuum tube has preloading effect. The coupling effect of dynamic compaction and vacuum pressure can accelerate the dissipation of pore water pressure, shorten the time interval between dynamic compaction for many times, and analyze the settlement of vacuum drainage method with low energy dynamic compaction. Based on the formation mechanism of double-layer foundation under impact load, the coupling effect of dynamic compaction and vacuum pressure can accelerate the dissipation of pore water pressure. The calculation formula of foundation settlement by vacuum drainage method of low energy dynamic compaction is deduced. The formula is applied to the settlement calculation of case engineering. Compared with the settlement data measured on the spot, the deviation between the calculated value and the measured value is 6 / 10, which can meet the requirements of engineering precision and can be used as a reference for similar projects.
【学位授予单位】：福建农林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU472

【参考文献】