Field Test Study About Bearing Capacity Of Single Root Pile In Loess Bedding

The requisite bearing capacity for the tunnel construction is firstly calculated in this paper with the loading-structure model considering the geological condition, wall-rock class and the loading condition. The calculation result is compared with the academic. And the result is drawn out that the requisite bearing capacity is larger than the academic. So the soundsill consoliding is necessary with root piles. Then some load tests of root piles in loess groundsill are developed in this paper. The tests in the ground of Xinxiaozegou tunnel including 11 single piles and 3 composite foundations are completed in DK52+382～+540. The results from the tests offer many important references for the root piles in loess groundsill. This paper inquires into the characteristics, application and theory of root piles underpinning. After combining the features of engineering geology and actural situation in the tunnel and using the way of comprehensive techniques and contrasting, the author believes that choosing root piles have less influnce to the building and its foundation, and more sensitivity to bearing capacity to reinforce the foundation of the tunnel.After continuous subsidence watching of the reinforce work, it is proved through practice that this technique is both economical and convenient, and working efficiency is improved greatly, and the equipments used are usual and the time cost is short and the technique is uncomplicated, especially, it can improve the earth under the foundation effectively. It not only opens up the scope of the root piles application, but also has the unique effect on the similar questions in our country. The three composite foundations respectively include three, eight and three single piles. Basing the data from field investigation, the carrying capacities of single piles and composite foundations are educed from the P-s curves. And the distortion of the composite foundations are analyzed...