Abstract:

In order to scientifically and reasonably determine the deformation joint spacing of the utility tunnel, based on the cast-in-situ concrete utility tunnel of Mingzhu Road in new and high-tech zone in Hefei, standard section utility tunnel and double standard section utility tunnel are considered. The spacing of deformation joints is set at 20 m, 30 m and 40 m respectively and the covering thickness of the upper soil of the utility tunnel is 2. 5 m, 3. 5 m and 5 m respectively. In this paper a three-dimensional numerical model is established using the finite element software Midas GTS NX, the stress and deformation of the cast-in-situ concrete utility tunnel in normal are calculated, and the influence of the deformation joint spacing of the utility tunnel on the structural stress and deformation is obtained. Through theoretical analysis and numerical calculation, the following conclusions are drawn: (1)Traffic load has a significant impact on the stress and deformation of the tunnel structure. (2)When the spacing of deformation joints is less than 30 m, the deformation of the structure does not change much, and when the spacing of deformation joints is more than 30 m, the deformation increases significantly with the increase of the standard section length. (3) When the spacing of deformation joints of the cast-in-situ concrete utility tunnel under typical geological condition in Hefei is set at 30 m, the stress and deformation of the utility tunnel are far less than the allowable value of the code, so the deformation joint spacing can be set at 40 m through scientific calculation.

Key words: utility tunnel, deformation joint, numerical model, setting spacing