关键词: 风积沙, 金属装配式基础, 真型试验, 上拔, 极限承载力

Abstract: More and more transmission lines pass through the desert area covered by aeolian sand, and steel grillage foundation has good applicability, but there are few field tests at present. In Yulin area of Shaanxi Province, southern edge of Maowusu sandy land, several groups of full-scale uplift tests of steel grillage foundation in aeolian sand ground were carried out, and the uplift bearing capacity, uplift and surface displacement, support and floor stress, upper earth pressure and other parameters were tested and analyzed. The results show that the uplift load-displacement curve of the steel grilage foundation is similar to that of the spread foundation, which can be divided into the approximate straight section, plastic transition section and linear instability section. When the cumulative uplift displacement reaches 21-23 mm, the foundation comes to the limit state. If small cracks appear on the ground surface around the top of the foundation during loading and propagate along the diagonal direction, the foundation will enter the limit state under the next level load. By analyzing the variation characteristics of the earth pressure on the upper part of the foundation, the fracture point on the uplift fracture surface of the foundation can be found, and the actual uplift angle can be calculated. The uplift bearing capacity calculated by the soil weight method in the existing codes is larger than the test value of ultimate uplift bearing capacity. It is suggested that the uplift angle should be 19.0o to 19.5o in the foundation design of relevant areas.

Key words: aeolian sand, steel grillage foundation, full-scale test, uplift, ultimate bearing capacity