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| Mechanism of composite grillage support with self-drilling anchors of tire tandems and vertical sheet drains |
| DONG Jianhua1，2，YUAN Fanglong1，2，3，DONG Xuguang1，2，PEI Meijuan1，2 |
(1. Key Laboratory of Disaster Mitigation in Civil Engineering of Gansu Province，Lanzhou University of Technology，Lanzhou，Gansu 730050，China；2. Western Engineering Research Center of Disaster Mitigation in Civil Engineering，Ministry of Education，Lanzhou University of Technology，Lanzhou，Gansu 730050，China；3. CCCC First Harbor
Engineering Company Ltd.，Tianjin 300222，China) |
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Abstract In order to solve the problems of draining and supporting for deep foundation pit in soft soil area，a new type of supporting structure with vertical sheet drains and self-drilling tire tandem anchors was put forward，and the working mechanism was studied in detail. The bearing capacity of the self-drilling tire tandem anchor under pore ware pressure was derived based on the cylindrical cavity expansion theory. The effect of prefabricated vertical sheet drain were analyzed and its influence on the uplift capacity of self-drilling tire tandem anchor was discussed with the finite element software ADINA. The bearing capacity value from simulation was compared with the theoretical one. The results show that the vertical sheet drains have a good dewatering effect，which can dissipate the pore pressure in the soil quickly and effectively. The axial force of anchors and the horizontal displacement of frame columns are significantly reduced with the prefabricated vertical sheet drains. The excessive pore water pressure caused by tire expansion can be dissipated immediately with the prefabricated vertical sheet drains. Furthermore，with the dissipation of pore water pressure，the displacement and strain of the soil along the axial direction are reduced，and the uplift capacity of anchors are improved. The theoretical uplift capacity is basically accordance with that from simulation，which proves the correctness of bearing capacity formula.
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2017, Vol. 36 
