边坡深部不均匀沉降条件下桩基础破坏特性的离心模型试验研究

我国地质条件复杂，岩土工程问题复杂多变。近年来，随着越来越多的工程开始建设，深部不均匀沉降条件在实际工程中经常出现，如：地下煤炭开采、基坑开挖、地下水位变化等，这种情况下上覆边坡及其上的基础容易发生严重的变形乃至破坏，对附近人民群众的生命财产安全造成了威胁。桩基础是目前工程中常用的边坡加固方式，因此，边坡深部不均匀沉降条件下的桩基础破坏特性亟待研究。离心模型试验在边坡变形破坏特性的研究中有明显的优势，在多种荷载条件下都取得了重要的研究成果。本文采用液压系统模拟深部不均匀沉降条件，进行了不同范围的深部不均匀沉降条件下桩基础破坏特性的离心模型试验，探究了不均匀沉降范围对桩基础变形破坏特性的影响机制，以及深部不均匀沉降条件下桩基础的破坏机理。结果表明，深部不均匀沉降条件下，桩基础所在土坡产生了3条主要的滑裂面，其中深部不均匀沉降区域附近的滑裂面是明显的滑动破坏，基础附近的滑裂面以张拉破坏为主。深部不均匀沉降首先导致了土体内部发生由下至上的滑动破坏，进而使桩基础发生了失稳，最终导致基础附近发生由上至下的破坏。深部不均匀沉降范围通过影响上部土体的变形局部化的时空分布情况改变了土坡滑裂面的位置与形状。深部不均匀沉降条件对土坡的影响存在一定的范围，影响区边界均呈绕桩分布。

Centrifuge Model Tests on the Failure Behavior of Pile Foundation Under the Condition of Deep Non-uniform Settlement in Soil Slopes

The geological conditions and geotechnical engineering problems are complex and changeable in China. Nowadays, as the construction of more and more engineering projects, deep non-uniform settlement conditions often occur in practical engineering, such as underground coal mining, foundation pit excavation and groundwater level change. It can lead to serious deformation and failure of the slopes and foundations overlying it, which may threaten the life and property safety of the people nearby. Pile foundation is a common method of slope reinforcement in engineering projects. Therefore, it is significant to study the failure behaviors of pile foundations under deep non-uniform settlement conditions. Centrifugal model test has obvious advantages in the study of slope deformation and failure behaviors, and some important results have been obtained under various loading conditions.Centrifuge model tests were conducted to investigate the deformation and failure behavior of pile foundations under the condition of deep non-uniform settlement which was simulated by the hydraulic system in different ranges. The influence mechanism of deep non-uniform settlement and the failure mechanism of pile foundation were investigated. The observation results show that under the condition of deep non-uniform settlement, there are three main slip surfaces in the slopes, among which the slip surfaces near the deep non-uniform settlement area are obvious sliding failure. The sliding surface near the foundation is mainly tensile failure. The deep non-uniform settlement first leads to the slip failure inside the soil from bottom to top, and then leads to the instability of the pile foundations, and finally leads to the slip surface near the foundation from top to bottom. The range of deep non-uniform settlement changes the location and shape of the slip surfaces of the slopes by influencing the spatial and temporal distribution of the deformation localization. There is an influence range of deep non-uniform settlement condition, and the boundary of the influence range is distributed around piles.