真空联合堆载预压加固软基施工技术及沉降分析

发布时间：2018-04-02 20:15

本文选题：真空联合堆载法　切入点：施工工艺　出处：《石家庄铁道大学》2015年硕士论文

【摘要】：以宁波连接线为工程背景,针对地软土地基较多、工程量大,施工期限短、地下水丰富与雨季降雨量大等不利因素,深入分析了真空预压法、堆载预压法以及真空联合堆载法加固机理。基于真空联合堆载预压处理公路软基,其施工工艺尤为重要,主要包括三个方面:塑料排水板的施工工艺、真空预压施工工艺和堆载预压施工工艺。塑料排水板施工中常出现四个方面需要注意的问题:插孔不宜缩孔;提拔导管时发生跟带现象;防止排水板破损及污染;根据现场土质情况确定插板速度。分析了真空预压法和堆载预压的加固机理,从加固机理、应力路径和强度增长3个方面对比分析了两种方法的特点。结合真空预压法和堆载预压,阐述了真空联合堆载预压施工技术,且真空预压法和堆载预压两者的固结效应可以叠加,其固结效应等同于真空联合堆载预压,从土体所受固结压力、侧向挤出变形和向内收缩变形互相抵消、塑料排水板作用3个方面讨论了叠加效果。从真空联合预压施工出发,根据现场实测施工进度分析,基于工期紧时间短考虑,对施工过程中前期真空度提高速率缓慢的原因进行分析。首先确定了密闭性能差是影响真空度提高速率缓慢的主要原因,然后对真空预压密实性能差末端要因进行确认,进而对其具体施工方法进行改进,提高了施工进度。阐述了真空联合堆载预压最终沉降变形的理论预测方法,即工程常用的分层总和法,推导了固结过程中水平固结度、竖向固结度和总固结度的计算方法。利用理论方法结合奉化三高连接线工程实际情况,计算了施工过程中总固结度的变化和最终沉降量,实测了真空联合堆载预压法现场沉降变化,并与理论最终变形量相比较。
[Abstract]:Taking Ningbo connection line as the engineering background, the vacuum preloading method is deeply analyzed in view of the unfavorable factors such as more soft ground foundation, large amount of construction, short construction period, abundant groundwater and heavy rainfall in the rainy season, etc.The reinforcement mechanism of surcharge preloading method and vacuum combined surcharge method.The construction technology of soft foundation treatment based on vacuum combined with surcharge preloading is particularly important, including three aspects: construction technology of plastic drainage plate, construction technology of vacuum preloading and construction technology of surcharge preloading.There are four problems to be paid attention to in the construction of plastic drainage board: the hole is not suitable for shrinkage; the phenomenon of belt following occurs when the pipe is lifted; the breakage and pollution of the drainage board are prevented; and the speed of the plug plate is determined according to the soil quality in the field.The strengthening mechanism of vacuum preloading method and surcharge preloading method is analyzed, and the characteristics of the two methods are compared and analyzed from three aspects: reinforcement mechanism, stress path and strength growth.Combined with vacuum preloading and surcharge preloading, the construction technology of vacuum combined surcharge preloading is expounded. The consolidation effect of vacuum preloading and surcharge preloading can be superimposed, and the consolidation effect is equal to that of vacuum combined surcharge preloading.The superposition effect is discussed from three aspects of consolidation pressure lateral extrusion deformation and inward shrinkage deformation and plastic drainage board action.Starting from the vacuum combined preloading construction, based on the analysis of the construction schedule measured on the spot and considering the short time limit, this paper analyzes the reasons for the slow increase rate of the vacuum degree in the early stage of the construction process.Firstly, it is determined that the poor sealing performance is the main reason that affects the slow increase rate of vacuum degree, and then the cause of the poor performance of vacuum precompaction is confirmed, and the concrete construction method is improved, and the construction progress is improved.The theoretical prediction method of the final settlement deformation of vacuum combined surcharge preloading is described, that is, the stratified summation method commonly used in engineering. The calculation methods of horizontal consolidation degree, vertical consolidation degree and total consolidation degree are derived.The change of total consolidation degree and final settlement in the construction process are calculated by using the theoretical method combined with the actual situation of Fenghua three High connecting Line Project. The field settlement changes of vacuum combined surcharge preloading method are measured and compared with the theoretical final deformation amount.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU472.33

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