振动沉管透水混凝土桩施工致堵机理与堵塞效应研究

Previous concrete piles(PCP) with high permeability and bearing capacity can not only accelerate the subgrade consolidation rate and reduce the settlement, but also significantly improve the anti-earthquake capacity of subgrade. PCP has broad prospects in application. However, for the installation method of vibrating-sinking tube, PCPs are likely to be clogged, and this can reduce the advantage of PCP. In this study, the laboratory simulation device of the vibrating-sinking tube installation will been developed. Based on tests, theoretical analyses and numerical simulations, the time history of excess pore water pressure in soil around piles caused by installation of PCP will be studied. The physical and chemical mechanisms of the interaction between liquefied soil and previous concrete during previous concrete hardening were interpreted. The soil particles movement and pore clogging process in previous concrete will be studied. The sensitivity analysis about influencing factors of PCP clogging will be conducted. The clogging evaluation method and clogging model will be developed. The influence of clogging on consolidation and earthquake-induced liquefaction of ground will be revealed. Based on researches on material, structure and installation technology, the control technology of PCP clogging induced by vibrating-sinking tube installation method will be proposed. The previous concrete proportion and installaton parameters will be explored to fit different types of deposites. This study can play an important role in improving PCP technology system.

透水混凝土桩兼具强透水性与高承载力于一体，不仅能加快地基固结速率，减小工后沉降，而且能显著提高地基的抗震能力，应用前景广阔。但是作为透水性桩，振动沉管透水混凝土桩在施工期间易发生堵塞，从而降低其性能的发挥。本项目拟研制振动沉管施工室内模拟装置，并结合理论分析和数值模拟等综合手段揭示振动沉管施工引起的桩周土体内超孔隙水压力的长消规律；诠释透水混凝土相变硬化过程中液化土体与透水混凝土相互作用的物理和化学机制，揭示土颗粒在透水混凝土中的运移和孔隙堵塞过程。对透水混凝土桩堵塞的影响因素进行灵敏度分析，建立堵塞评价方法和堵塞模型，揭示桩体不同程度的堵塞对复合地基固结和地基地震液化的影响规律。最终从材料、结构和施工工艺等多个方面提出振动沉管透水混凝土桩施工致堵的控制技术，寻求适合不同地质类型的透水混凝土材料配比和工艺参数。本项目研究对推动透水混凝土桩技术体系的建立具有重要作用。

本项目在透水性混凝土桩复合地基工作机理与关键技术研究（51078222）的研究基础上继续深入研究，提出了振动沉管透水混凝土桩施工致堵机理与堵塞效应研究（51778346）。本项目旨在完善透水混凝土桩复合地基处理技术体系，主要解决实际应用过程中透水混凝土桩施工引起的孔隙堵塞问题，为透水混凝土桩复合地基处理技术的推广应用提供相应的理论和技术支撑。项目通过理论分析、计算机断层扫描技术、室内试验、等比模型试验和数值模拟等方法揭示了振动沉管透水混凝土桩的施工致堵机理；建立了透水混凝土桩防堵塞强化处理方法并提出了成套施工技术；阐明了透水混凝土桩堵塞对地基固结和振动液化的影响规律；完成了透水混凝土孔隙结构建模和颗粒输运数值模拟。最后，从材料选取、结构优化设计和施工工艺参数确定等多方面完善了振动沉管透水混凝土桩防堵塞成套应用技术，并给出了适合不同地质类型的透水混凝土材料配比和工艺参数。透水混凝土桩复合地基处理成套技术实体工程性能优良、成熟度高，应用前景广阔。