基于透明土技术的加筋地基模型试验

Model Tests of Reinforced Foundation Based on Transparent Soil Technique

采用透明土技术,开展了5组不同筋材长度和加筋深度(层数)的加筋地基平面应变模型试验,以及1组无筋地基对比试验,以研究在条形基础荷载下加筋地基内部位移场演化及滑移破坏过程,并探讨其荷载—沉降特性.结果表明,加筋地基中的土体在基础沉降过程中,首先在加筋区的两侧底部非加筋区位置累积水平位移,并自下而上向加筋层扩展,致使筋材自下而上依次断裂,最终形成宏观剪切破坏面;加筋地基在基础沉降过程中形成两个应力扩散区,分别沿筋材弯折段和基础边缘向下扩展,前者扩散角是后者的2.5倍左右;加筋地基和无筋地基均表现为普朗特尔滑动破坏模式,加筋地基滑动面深度和宽度基本随加筋深度和加筋长度的增大而增大;当筋材强度不足时,加长筋材长度对加筋地基承载力的提高不起作用,而增大加筋层数对承载力影响显著.

Five groups of model tests of reinforced foundation with different reinforcement lengths and depths （layer numbers） as well as 1 group of model test of unreinforced foundation were carried out by transparent technique. The evolution of displacement field in the reinforced foundation and procedure of slide failure under strip loading were investigated. The load-settlement characteristic of reinforced foundation was also discussed. The results show that duringthe settlement of trip footing, horizontal displacement accumulates first in the unreinforced zone near the lower right and the left corner of the reinforced zone, and then extends upward to reinforcement layers, which causes the tensile failure of the reinforcements successively from bottom to top and at last forms micro shear failure surface. Two stress diffusion zones are formed during the settlement of the strip footing. The two zones extend downward along the bend section of each reinforcement layers and the strip footing edges, respectively. The stress diffusion angle along the bend section is 2.5 times of that along the trip footing edges. Both of reinforced and unreinforced foundations fail in Prandtl slide mode. The depth and width of the slip surfaces increase with an increase of reinforced depth and reinforcement length. When the strength of reinforcements is deficient, extending reinforcements has little effect on the bearing capacity of the reinforced foundation, whereas the increasing reinforcement layers can significantly affect the bearing capacity.