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

The swelling pressure and deformation of swelling rocks are directly related to theirmoisture content or humidity, if the humidity distribution of the tunnel surrounding rocks isgiven in advance, then we can realize and calculate the swelling load of supporting structureswhich are influenced by tunnel surrounding rocks, and it is beneficial for carrying out thereasonable designing of supporting structures as well, when tunnel excavation within theswelling rocks is launched. Unfortunately, So far, no one around the word has had someresearch on the humidity distribution characteristics of the tunnel surrounding rocks withinswelling rocks. This paper is innovatively applied with the testing method of similar materialmodel to do some research on the relationship between the water contained content in tunnelsurrounding rocks which are used drilling and blasting construction method, the size of theoriginal stress and the excavation process of tunnel, and moreover, on exploring swellingsurrounding rocks which is in different geological environments and the humidity distributionof tunnel surrounding rocks under the conditions of construction process. The study in thispaper is also used to provide some references to design and construct the supporting structurein tunnel within swelling rocks.Firstly, this paper is divided into three parts: designing the testing method of similarmaterial model, developing similar materials and the instrument which is used to test moisturecontent and model tests.The research of the development of similar materials is also divided into three parts: thedevelopment of similar materials of swelling rocks, the choice of material of bolt-shot Cretesupporting and the design of similar material of anchor. And the development of testequipment to test moisture content mainly includes two parts: the development and calibrationof test equipment and gypsum probe, and the design of model test involves the design of testdevice and roadway section.Through those test research, we can get a better ratio of similar materials of swellingrocks, namely, fine sand: bentonite: gypsum: cement=1000:1200:450:350, withcontrolling the moisture content as23.3%, which is easy to build and measure.The developing of probes has to consider user-friendly, just taking a simple straight lineelectrode form, which use plaster for moisture sensitive materials, producing similar materialmoisture content measurement sensor. According to the resistance value of the sensor and thewater content of the relationship of sensor calibration, using Matlab polynomial fittingmethod for testing moisture content.Then, we are focusing on the expansion of rocks surrounding rock humidity field and stress field model test study. The research of similar material model is based on roadwaybolting and shot Crete lining, considers the project in which the initial stress level, andwhether set the invert or not and the three factors of timing to set invert, therefore the papertotal designs three models and six programs to explore the expansion of humidity fielddistribution of Rock Roadway, and meanwhile the paper has to take into account about thestress of the surrounding rock tunnel vaults and acquisition and analysis of data of edge statedeformation.According to the research:①Water for tunnel excavation and support the process of construction, size anddistribution of the surrounding rock water content, mainly goes to the large water contentdistribution characteristics. The initial water content of surrounding rock also has an impacton the final moisture content distribution, but there is no significant influence of excavationconstruction water.②Moisture distribution of the three model tests have the same characteristics, due to thewater for construction retention in the backplane. The region of high water content is formedat the bottom, after penetration and capillary action, the water to migrate away from the walland the dome position.③The effect on the surrounding rock moisture stress environment is not obvious. Underhigh stress environment, the rate of penetration is small, but as time goes on, the penetrationalso goes on. So, there is no different between high-low stress environments.④Which is quickly increased rapidly to an extreme value at first, then decreased to astable value, and performed a change for increased and then decreased law changephenomenon，The surrounding rock has the phenomena of unloading and stress redistributionafter excavation.⑤The effect whether to build the invert and the time to build invert on the surroundingrock water content is obvious. Invert backplane is to avoid the backplane prolonged flooding.Which lag20m or50m, the sooner build is better than later, so that the backplane is protectedas soon as possible to avoid unnecessary water increase.