|
|
【答案】应助回帖
★ ★ ★ ★ ★ ★ ★ ★ ★ ★
suetung8: 金币+10, 基金HEPI+1, ★★★★★最佳答案, 辛苦了，多谢 2013-03-13 09:02:44
中文摘要： 考察和调研了西北沙漠地区：库布齐沙漠，毛乌素沙漠，腾格里沙漠和乌兰布和沙漠，进行了现场取样和土工试验。并确定了现场试验场点和试验用土采样点。研究确定了使用经编土工格栅为风砂土的加筋材料，进行了土工格栅加筋土扩展基础模型上拔试验和承压试验。研究了加筋土扩展基础在上拔荷载和下压荷载作用下的力学性能，对几种不同的土工格栅铺设方式进行了研究，提出了承载力高、抗变形能力强的水平铺设一层、两层土工格栅的方
中文主题词： 加筋地基；扩展基础；抗拔性能；承压性能；颗粒流模拟
英文摘要: Field surveys in the representative desert areas of Hobq and Mu Us on Ordos plateau and Tengger and Ulan Buh on Alxa Plateau ware conducted. From engineering point of view, the relativity of the formation of the deserts is discussed, and the necessity of improving the physical, mechanical and engineering properties of the aeolian sand is emphasized. Two kinds of frictional action tests were performed; four types of geo-grid reinforcement were arranged. The behavior and engineering properties of these improved foundations of various embedment depths under uplift tests were compared with those of the unreinforced. It was found that the uplift capacity and resistance to deformation increased. Reasonable arrangement and installation of geo-grids were chosen, width of geo-grids is 1.0b-2.0b (b is width of spread foundation); shapes of planes of sliding measured and characteristics of uplift loading and displacements studied. It is suggested that the mechanism of developing uplift bearing capacity is due to the compression of soils, shearing resistance of soils and the mutual frictional action between geo-grids and soils. Based on the suggested failure mode of reinforced soils, the formula for calculating uplift bearing capacity of spread foundations on reinforced aeolian sand is derived. Also the mathematical model related to uplift loading and displacement valid only under the condition d/b equal or smaller than two is recommended. The calculated results are close to those measured. PFC simulates numerically the formation of Aeolian sand particles, spread foundations and the walls of model test box. Uplift loading is applied step by step to the simulated foundations. Uplifting displacements, distribution of particles and contact forces of particles are observed on foundations of two different embedment. The change of arrangements of particles from before to after uplift loading, the directions of particle displacements and the affected zone together with the rupture surface in soils and load versus displacement are analyzed. These are compared with the results obtained from model and prototype tests. |
|
回复此楼