土体常规加卸荷对桩基影响模型试验系统研制与应用  

Development and application of simulation system for model piles impacted by routine loading and unloading of soil

作　　者：楼晓明[1,2] 李德宁[1,2] 杨敏[1,2] 杨晶[1,2] 

机构地区：[1]同济大学岩土及地下工程教育部重点实验室,上海200092 [2]同济大学地下建筑与工程系,上海200092

出　　处：《岩土工程学报》2012年第8期1509-1515,共7页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(50978201)

摘　　要：为模拟土体加卸荷对桩基摩阻力产生的影响,研制了土体加卸荷对桩基影响模拟试验系统。该系统包括加卸荷系统、模型桩、量测系统及数据自动采集系统4个子系统。该系统可通过气压加载法在大直径土样顶面以较高荷载进行加卸荷,模拟不同土性、不同桩端约束条件下土体沉降或回弹对模型桩产生的影响,并通过试验验证了其有效性和可靠性。试验表明,系统智能化程度高,可实现大荷载长期稳压,量测系统灵敏度高稳定性好;不同桩端约束条件对桩侧摩阻力分布影响很大;土样在卸荷比达到约0.8发生强回弹,但对桩端嵌固条件下桩顶2/3桩长范围和桩端自由条件下全桩长桩侧摩阻力影响不明显。系统可用于模拟桩间土大面积均匀加卸荷对工程桩的影响。A simulation system is developed to investigate the change in skin friction of piles due to the loading and unloading on the surface of soil. The system consists of four subsystems： loading and unloading, model piles, measuring system and automatic data acquisition system. The system can get higher pressure with the help of the pneumatic loading method so as to simulate the impact of soil compression and rebound on model piles under different soil properties and end restraint conditions. The validity of the apparatus is verified by elementary tests. The test results show that the system with high intelligence can achieve long-term constant load. Different end restraint conditions of piles are observed to have a significant influence on distribution of skin friction along the pile. And the strong rebound of the soil has little effect on skin friction of the upper part for bottom fixed piles and the whole for bottom free piles when the unloading ratio reaches 0.8. The system can be used to simulate the effect of the soil loading and unloading on piles.

关 键 词：加卸荷 摩阻力 中性点 模型试验 模型桩 

分 类 号：TU447[建筑科学—岩土工程]