行车荷载下饱和土高速路基排水(渗流)动力反应与沉降分析

The dynamic response of saturated soil subgrade of super highway subjected to the traffic loads is a research hotspot up to now, and accidents still occur in the saturated soft subgrade. It is due to three main causes:(1)the primary cause for the accidents is not indicated; (2) the key physical quantities in soil mechanics and the limit indexes in design for controlling settlement of soft soil subgrade are not put forward; (3)the shortage of further study on basic theory. The analysis of response on the saturated soil subjected to dynamic action under drainage is an outstanding problem in soil dynamics, and the similar issue also appears in the saturated soft soil project. Because the permeability coefficient of saturated soft soil is small, the period of drainage is long, and the porous excess water pressure can generated. The porous excess water pressure can cause seepage and consolidation, then they may lead to the subgrade settlement, it is the immediate cause of engineering accidents. In view of this, the investigation of the proposal about the dynamic response on the saturated soft subgrade subjected to traffic load under drainage(with seepage) by the fluid phase solution of Biot's equations and other previous research results, and research the differential settlement of saturated soft subgrade. Based on "dynamic seepage flux" as the key physical quantities in design and control the differential settlement of subgrade is studied. The control measures for the selection of subgrade site and handling methods to subgrade are put forward. It can be taken to relieve or avoid damage in subgrade settlement, so as to serve to the national economy developing.

行车荷载对饱和土路基作用的动力响应"研究至今尚是热门，但饱和软土路基上还发生事故。这该是：以往研究(1)没探明导致事故发生的根本原因；(2)没真正提出控制路基软土沉降的关键土力学物理量及设计限值指标，(3)没针对短缺的基础理论进行深入研究。饱和土在动力作用下伴有排水的反应分析，是土动力学中未解决的悬题，相似的问题也出现在饱和软土工程上。饱和软土渗透系数小，排水时间长，会出现超孔隙水压力。超孔隙水压伴随着渗流和固结，它们引起了路基面沉降，是工程失事的直接原因。鉴此，申请者通过Biot方程流相解答及已有成果,研究饱和土路基在行车荷载作用下伴有排水(渗流)的动力反应；认识饱和软土路基产生的不均匀沉降。并以"动力渗流排水量"作为关键设计控制物理量值指标，分析路基不均匀沉降；为路基的选址，路基处理方法的选择，提出该采取的措施；从而缓解或解决软土路基沉降灾害，为国民经济建设服务。

我国高速公路早突破15万km，跃居世界第一。未来 10～15 年，还将集中建设、加快成网，体量会十分巨大。我国地大，路基所处环境复杂，建成的高速公路在运行中也会伴随一些问题。软土路基行车沉降引起的桥头跳车和路面破坏，就是普遍关注，但又未解决的重要问题。因此，分析、了解软土路基行车沉降力学机制，如何设计高速公路，也成了高速公路建设乃至运行中亟待解决的关键问题，不然可能酿出灾难。因此，研究与处置高速软土路基行车沉降也是国家重大工程面临的迫切任务。本基金研究本着这一宗旨进行。. 对照年度计划，除了出访未进行外，本基金进度基本按所附计划进行，并且较好地完成。在研究的过程中 申请者利用偏微分方程Kupradze解理论，完成了Biot动力学方程的快，慢纵波势解耦 (已成经典解答)，得到了Stokes状态的时域和频域的方程闭合解；完成了两相介质Betti-Rayleigh定理对Somigliana和Volterra积分方程运算的参量消元转换；给出了Doppler效应的运动源Biot动力学方程的U-P解答时域与频域Green函数。创建了两相介质边界元弱、强奇异积分的处理方法，完成了行车荷载下位移、应力、孔压和排水流量等一系列精确解答。在本基金课题的试验与测试所涉的工作中，完善了动三轴排水状态试验阐明了低频下的排水量要大于高频下的排水量。组织完成了行车荷载对高速公路饱和土路基孔压影响的测试工作。封道测试分析结果表明dopper效应的影响作用明显，试验较为成功。实验结果也具有较典型意义。在基金的研究中将理论分析的实际运行工况调查结合，以杭州湾滨海平原高速公路桥梁别车端与迎车端沉降的差值，阐述沉降的Doppler效应现象，并根据高速公路桥端多年的实际维修填铺施工记录参数给出了沉降曲线。研究者希望提供实际设计使用。