沉井下沉期荷载分布特征的细观试验  

Meso-experiment on Caisson Load Distribution Characteristics During Sinking

作　　者：穆保岗[1] 别倩 赵学亮[1] 龚维明[1] 

机构地区：[1]东南大学土木工程学院,江苏南京210096 [2]南京水务集团有限公司,江苏南京226019

出　　处：《中国公路学报》2014年第9期49-56,共8页China Journal of Highway and Transport

基　　金：国家重点基础研究发展计划("九七三"计划)项目(2013CB036304);江苏省自然科学基金项目(BK2011614);"十二五"交通运输重大科技专项项目(2011 318 494 160)

摘　　要：为了准确分析沉井下沉期荷载分布特征可能受到的施工行为影响,设计了3组不同尺寸的沉井模型模拟下沉。在试验箱内分层铺设彩色标准砂,采取吸砂等助沉措施,利用CCD技术连续跟踪拍摄,观测地表沉陷范围、颗粒流动趋势,测量侧壁土压力,并采用二维颗粒流程序PFC2D对试验过程进行模拟。研究结果表明:沉井下沉期的地表沉陷范围与沉井平面尺寸相关,由于吸砂形成的应力松弛影响,沉井侧壁的土压力在深度方向分布呈现先增大后减小的趋势,PFC程序分析的结果与室内模拟的规律较为一致;沉井下沉期间荷载分布特征不同于现行规范规定的线性分布,应考虑取土下沉的扰动行为对其荷载分布特征的影响。In order to investigate the load distribution characteristics of caissons possibly affected by the construction during sinking, three different sizes of caissons were designed to simulate the sinking process of the caisson. Colored standard sands were laid in experimental box hierarchically. Sand suction was employed to help sink the caisson. Continuous photographic technique was taken with CCD camera to capture the surface subsidence region and particle flow trend. Lateral earth pressure on the caisson was measured. Two-dimensional particle flow code （PFC2D） was employed to simulate the experiment. The results show that the surface subsidence region of the caisson during sinking is related to the size of the caisson. The lateral earth pressure on the caisson increases first and then decreases as a result of the stress relaxation due to the sand suction, which is consistent with the numerical results from PFC. The load distribution characteristics during the sinking are different from the linear distribution which is assumed in the current specification. The influence of the soil subsidence disturbance on the load distribution should be considered.

关 键 词：桥梁工程 沉井 细观试验 荷载分布特征 颗粒流 

分 类 号：U445.557[建筑科学—桥梁与隧道工程]