| Based on the engineering background of a submarine tunnel,the model of a submarine tunnel with a similarity ratio of 1/20 is made by using gypsum,and the proportioning test of similar soil was carried out.A shaking table device for dynamic response of the water-seabed-submarine tunnel was designed to study the seismic response of the submarine tunnel under different water depths.On the other hand,based on the two-dimensional uniform visco-elastic artificial boundary and the equivalent load input method of ground motion,a two-dimensional free field model of saturated soil was established by Open SEES software to study the accuracy of the twodimensional uniform visco-elastic artificial boundary element.Secondly,a watersaturated soil free field model was established to study the influence of the depth of the sea water on the seismic response of the free field.Finally,a saturated soil-submarine tunnel model was established,the overall model was used to study the seismic response of the submarine tunnel.The main work and achievements of this paper are as follows:(1)Based on similarity theory,using gypsum and barite powder to carry out tunnel model material proportion test,using sand,calcium carbonate,barite powder to carry out similar soil proportion test.The waterproofing measures of gypsum products were studied and finally applied to the waterproofing treatment of tunnel models.Considering the size of the shaking table and the similarity ratio of size of submarine tunnel model,a model box was designed and manufactured.The layout of the model box was designed,and the sensors installed in the submarine tunnel were waterproof treated.Finally,according to the principle of liquid pressure,a set of dynamic response shaking table device of submarine tunnel with variable water pressure was designed to carry out shaking table test of submarine tunnel.(2)Based on OpenSEES software,a two-dimensional free-field model of saturated soil was established,and the results of two-dimensional visco-elastic artificial boundary,viscous boundary,fixed boundary model and extended model are compared and analyzed.The results show that the two-dimensional visco-elastic artificial boundary can simulate the infinite domain problem in finite domain.Then the free-field model of water-saturated soil was established,and the influence of water-covered layer on freefield seismic model was studied.The results show that under the action of P-wave and SV-wave,the influence of water depth on the displacement response of free-field is almost negligible.Under the action of P-wave,the vertical acceleration of free-field decreases with the increase of water depth,while under the action of SV-wave,the horizontal acceleration of free-field decreases gradually.With the increase of water depth,there is a trend of gradual increase.Finally,a water-saturated soil-subsea tunnel model is established to study the seismic response of the subsea tunnel under different water depths when P-wave and SV-wave incident vertically.The results show that the internal force of the submarine tunnel increases gradually with the increase of water depth,and the internal force at the shoulder,waist and foot of the tunnel is larger,therefore special attention should be paid to the structural design.(3)The results of shaking table test are similar to those of numerical simulation.The internal forces or stresses at the arch shoulder and arch foot of submarine tunnels are larger under seismic load,while those at the arch crown and inverted arch are smaller.The change of seawater depth has some influence on the acceleration,relative displacement,pore pressure and internal forces of tunnels,but overall,it has little effect,especially on the relative displacement. |
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