采动地表土体沉陷对桥梁桩基影响试验研究  

Experimental study on mining-induced surface subsidence influence on the pile foundation of bridge

作　　者：张敏霞[1] 徐平[1] 高帅[1] 崔文杰[1] 

机构地区：[1]河南理工大学土木工程学院,河南焦作454003

出　　处：《岩石力学与工程学报》2017年第A02期4122-4133,共12页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金青年基金资助项目(51508166);河南省高等学校重点科研项目(15A560007);河南理工大学青年骨干教师项目~~

摘　　要：因地下煤层开采引发的地表土体沉陷,对其上方公路或铁路桥梁桩基产生严重危害,甚至引发整个桥梁失稳破坏。基于采动引发的地表沉陷规律和地表沉陷预计概率积分法原理,研制了一套模拟地表沉陷土体桩基载荷试验系统。采用该系统对位于地表不同沉陷位置的4根模型桩开展了试验研究;试验实测了桩身轴力、桩侧摩阻力及桩–土相对位移在地表沉陷过程中的变化;试验实测地表沉降量和概率积分法计算值二者吻合较好,证明了该试验系统模拟地表沉陷的可靠性;试验发现4根试验模型桩桩身轴力和桩侧摩阻力的变化均与所在的地表沉陷曲率变化相关,地表沉陷曲率变化越大,则桩身轴力和桩侧摩阻力变化就越大;桩–土相对位移分析表明,地表沉陷曲率越大,则桩–土相对位移越大,且可能产生桩侧负摩阻力,加剧桩体下沉,引发上部桥梁结构产生不均匀沉降,甚至破坏。研究结果对于采动区桥梁桩基的保护与加固具有重要参考价值。Surface subsidence induced by mining has seriously harmed pile foundation of high or railway bridge,and even causes instability and failure of the whole bridge.Based on the surface subsidence law subjected to mining and the principle of Probability Integral Method（PIM） prediction,a set of pile foundation load test system was developed,which could simulate surface subsidence induced by mining.Using this test system,four model piles located at different subsidence positions were carried out to study the bearing characteristics of existing load piles of bridge in the process of surface subsidence.Pile shaft force,side resistance and pile-soil relative displacement were obtained through the pre-set test elements.Test results show that the measured surface settlement has a good match with the calculation of PIM,which confirms the reliability of the test system to simulate mining surface subsidence.The variation of shaft force and the side resistance of four test piles are related to the location of surface subsidence curvature.The greater variation of the surface subsidence curvature,the greater change shaft force and the side resistance are.The relative displacement analysis of the pile-soil shows that the larger the surface subsidence curvature is,the larger the relative displacement of the pile-soil is,and the negative skin friction of the pile would generate,which will aggravate the pile foundation settlement and cause the upper bridge structure to produce uneven settlement,or even damage.The study results will be helpful to protect and reinforce bridge pile foundations in mining area.

关 键 词：基础工程 采动地表土体沉陷 桥梁桩基 模型试验 桩–土相互作用 荷载传递机制 

分 类 号：TU47[建筑科学—结构工程]