湿陷性黄土层桩网结构环保型压浆承载机理及车载动力响应

Driven by the "The Belt and The Road" strategy, highways and railways in the northwestern region of China have continued to develop.However, a large number of collapsible loess is distributed in the northwest region, which will seriously affect the high-speed operation of vehicles.Environmental- friendly grouting can not only make full use of fly ash waste to reduce environmental pollution,but also improve the bearing properties of collapsible loess, thereby increasing its bearing capacity and eliminating the pavement subsidence caused by the heavy load of high-speed vehicles repeatedly. Therefore, the project would be put up to explore the environment-friendly grouting load transfer mechanism of pile-net structrues in collapsible loess by field surveys, large scale lab model tests, and numerical simulation techniques.Under the repeated action of heavy vehicles, the dynamic response of composite foundations is focused on the study of subgrade settlement characteristics of the subgrade after grouting pile-net structure under heavy traffic loads, and the full-process damage mechanism and failure modes of the loess composite roadbed are revealed to optimize the design of environment-friendly grouting parameters for collapsible loesspile-net structure.On this basis,the calculation model of enhancing the ultimate bearing capacity of environment-friendly grouting pile-net structure with collapsible loess is established, and then the settlement calculation method of heavy traffic loads under repeated action is proposed.The research results provide a theoretical basis for the treatment methods and construction techniques of highways and high-speed railways in the collapsible loess area of northwest China.

在“一带一路”战略驱动下，我国西北地区高速公路、铁路得到继续发展。而西北地区分布大量湿陷性黄土，这将严重影响车辆的高速运营。环保型压浆不但充分利用粉煤灰废料，以减轻环境污染，还可改善湿陷性黄土承载性状,从而提高其承载力，并消除其在高速车辆重载反复作用下引发的路面沉陷。为此，本项目拟通过现场调查、室内大比例尺模型试验和与数值仿真技术，探索湿陷性黄土层桩网结构环保型压浆荷载传递机理，在重型车辆反复作用下复合地基的动力响应，着重研究在重型交通荷载下桩网结构环保型压浆后的路基路面沉降特性，揭示黄土复合路基的全过程破坏机理及模式等，以便优化湿陷性黄土桩网结构环保型压浆参数设计。在此基础上，建立湿陷性黄土环保型压浆增强地基极限承载力的计算模型，进而提出在重型交通荷载反复作用下其沉降计算方法。研究成果为我国西北湿陷性黄土地区修建高速公路与高速铁路的路基处理方法和施工技术提供理论依据。

在“一带一路”战略驱动下，我国西北地区的高速公路、高速铁路得到快速稳步发展。而西北地区分布大量的湿陷性黄土，这将严重影响高速车辆的平稳安全运营。粉煤灰与煤矸石复合桩不但可充分利用粉煤灰、煤矸石等工业废料，以减轻对堆放场地等环境污染，而且还可以改善湿陷性黄土的承载性状，从而提高复合路基的承载力与变形特性，并消除其在高速重载车辆反复作用下引发的路面沉陷。鉴此，本项目通过了大量现场调查、室内大比例尺模型试验和与数值计算与仿真技术，探索了湿陷性黄土填筑路堤煤矸石桩复合路基的荷载传递机理，尤其是在重型车辆反复作用下复合路基的动力工作性能。项目系统研究了在高速列车荷载作用下煤矸石复合路基承载与沉降特性，对煤矸石桩体设计参数进行分析，研究桩长、桩间距、桩体模量变化对复合地基应力场与位移场的影响，通过大型室内模型试验研究了桩网结构路基在五级静力荷载下的桩身应力应变、桩土荷载分担比、路堤内部土压力分布特征、土拱效应的发展与分布规律、以及格栅垫层的应力分布特点，通过对桩网结构路基施加动力荷载，探究了桩网结构在动载下的桩土应力分布、路堤内土动应力分布、动载下土拱效应的发展变化规律，模拟了时速300km的列车荷载对结构的动力响应；建立了桩网结构路基三维数值计算模型，研究了桩网结构的荷载传递规律及动力响应规律；还分析了路堤填土高度、桩间距等主要参数对桩网结构路基力学性能和土拱效应的影响，揭示了黄土复合路基的全过程破坏的作用机理、破坏模式等；建立了湿陷性黄土环保型压浆桩增强地基极限承载力的计算模型，提出了在重型交通荷载反复作用下其沉降计算方法。研究成果将为我国西北湿陷性黄土地区修建高速公路与高速铁路的路基处理方法和施工技术提供理论依据。