【作者】 王强；

【导师】 顾长存；

【作者基本信息】 河海大学 ， 岩土工程， 2004， 硕士

【摘要】 塑料板排水预压法是在砂井排水预压法的基础上发展起来的，是一种行之有效的软基加固方法。近年来随着国民经济的发展，广泛地应用于道路、堆场、港口、机场等各类土木工程的软基加固中，并且取得了良好的加固效果，但该法的加固机理及计算方法等诸多方面还存在明显不足和争议之处。 本文在前人工作的基础上，通过试验研究、理论分析、数值计算等手段主要进行了以下几方面地工作： (Ⅰ)分析了大量现场观测成果及室内外试验资料，从经典力学和微观渗流两个角度解释了塑料板排水真空-堆载联合预压法加固软基机理，总结了该法加固的土体变形特点、孔隙水压力变化规律。 (Ⅱ)根据实测资料，讨论了加固区形状对加固效果的影响；对塑料板排水预压法适用的场地、土质条件以及塑料排水板的有效打设深度进行了探讨；提出了该法卸载条件的计算方法，并结合实践工程进行了验证。 (Ⅲ)在土体损伤理论的基础上建立了考虑结构损伤、排水板加筋作用的瞬时沉降计算公式，分析了影响土体沉降的主要因素，提出了对按单向分层总和法计算的固结沉降量进行体积应变、侧向位移、土体结构损伤三项修正的方法，以上述三个修正系数取代原来单一的综合经验系数，使沉降计算值与实测值更接近。分析了影响次固结变形的主要因素，并提出了卸除超载后，软基在永久荷载作用下的工后沉降计算方法。 (Ⅳ)采用平面应变比奥固结有限元法对淮河入海水道某涵闸软基加固工程进行了数值计算，通过对比数值计算结果、实测值及简化方法计算结果，证明了本文提出的沉降计算简化方法的正确性和适用性，所得结论对于同类工程具有一定的参考价值。更多还原

【Abstract】 Among soft-base improvement methods, prefabricated drain preloading is one of the most popular vertical drain methods. It is developed from sand drain preloading method. With the development of country economy, the method was used widely in soft ground reinforcement of several lands of civil engineering projects, such as road, port, airdrome, and so on. And favorable effect is obtained. However, there are some flaws and dispute about improvement principle and design theory.Based on the former research, several works in this paper is listed as follow, which is studied by experiment research, theoretical analysis and numerical calculate:Firstly, based on local observation and laboratory experiment result, consolidation mechanism of vacuum-surcharge preloading is analyzed form typical mechanics and microstructure seepage factor. A great deal of observed dada is employed to analyze the deformation characteristics of soil after being treated and variation law of pore water pressure.Secondly, the shape of reinforcement area which have a great influence upon the effect is discussed here, effective embedding depth of plastic drain board and the applying conditions for prefabricated drain preloading method are researched. Combined with practice project, a new unloading criterion is proposed.Thirdly, a calculation formula of distortion settlement is established by considering soil structure damage and plastic drain board restraining displacement of soft foundation. Starting with discussing the main factors affecting settlement of consolidated foundation, a reasonable method to modify the calculated settlement of soft foundation by layer-wise summation method is presented here. With calculable coefficients of volume deformation, lateral displacement and structure damage to modify the settlement will be closed to measurer settlement. Based on studying main factors affecting secondary settlement, a method to estimate the post-construction settlement after removal of surcharge is proposed.Fourthly, compared with calculate results for typical section of a culvert soft-base reinforcement project in the water way to sea of Huaihe river engineering by the plane strain FEM based on Biot consolidation theory, measured data and simple calculation result, the simple calculation method proposed in this paper is proved to be reasonable and verified, and is more referenced by congener project.更多还原