Simiral Material Model Test Study On The Humidity Field Of Tunnel Surrounding Rocks Within Swelling Rocks

The swelling power and deformation of swelling rocks are directly related to themoisture or humidity of swelling rocks, when tunnel excavation within swelling rocks islaunched, the construction and supporting structures design wil be carried out reasonablely ifthe humidity of tunnel surrounding rocks is given in advance. So far, no one at home andabroad has had some study on the characteristics of the humidity distribution of tunnelsurrounding rocks within swelling rocks. The similar materials model test method, in thispaper, is innovatively applied to have some study on the relationship between the watercontained in swelling tunnel surrounding rocks used drilling and blasting construction methodand the size of the original stress and the tunnel excavation process to explore the humiditydistribution of tunnel surrounding rocks within swelling rocks which is in different geologicalenvironments and under the conditions of construction process. The study in this paper is alsoused to provide some references to design supporting structure in tunnel within swellingrocks.Firstly, the similar material model test is designed in this paper, including the study ofsimilar material and model test design. The research of similar material on swelling rocks, thechoice of material of anchor and shotcrete supporting, the design of material of invert areintroduced in the study of similar marterial. And the design of test equipment and the choiceof tunnel cross-section are contained in model test design. Through the test research, a betterratio of similar materials for swelling rocks is founded, namely, fine sand: flour: bentonite:gypsum: cement: water=2:0.153:0.5:0.3:0.2:1, where3%glycerol is added to the water.Secondly, three similar material model tests such as I, II and III are applied to explorehumidity field distribution of tunnel surrounding rocks within swelling rocks and analyzesome data collected on the stress and deformation of tunnel surrounding rocks in this paper,which is on the basic of the anchor and shotcrete supporting method and taking three facetssuch as the initial stress level, whether to set up invert-structure and when to set upinvert-structure into account.Some conclusions are made from three model tests as following.①The initial stress level of the surrounding rocks has little effect on humiditydistribution of tunnel surrounding rocks, but setting up invert-structure can significantlyreduce the humidity range of law.②The stress and deformation of tunnel surrounding rocks have something with theinitial stress and setting up invert-structure, which are affected indirectly by the humidity distribution.③The hoop stress on the direction of the arch middle line, the vertical wall middle lineand the bottom center line has overally such laws in tunnel, the pressure rapidly increases to afirst extreme value,then decreases to a stable value as far from the wall of tunnel, expressingthe stress as a "single peak" type.④The deformation of tunnel surrounding rocks in swelling rocks has a line axis ofsymmetry connecting the center line of the the arch and the bottom, presenting regular orirregular loop surround the the tunnel.