| In recent years, neighborhood tunnel have a great advantages in project land, projectinvestment and construction technology and other aspects, more and more by the buildingdepartment favored. But in the tunnel construction, project accident has increased graduallycaused by the engineering geological conditions, especially the swelling rock. Swelling rockhas the characteristics of swelling and lost shrinkage by water, and the surounding rock stressand strain influence by the surrounding water and the surrounding rock pressure. At present,there are lots of aspects research on the surrounding rock of tunnel surrounding rock in theexpansion of the stress and strain. But there is little research on surrounding rock waterchange. Swelling rock water distribution has great influence on the stability of surroundingrock of neighborhood tunnel, explore the distribution of water has the research significance.Through indoor model test can effectively simulate the actual engineering, and it can help forthe neighborhood tunnel engineering structure stability analysis and construction.Firstly, this paper were studied on the expansion of similar materials. In the swellingrock similar material preparation process used to sand, bentonite, limestone, admixtures(hydroxypropyl methylcellulose) and the construction of water as material, using the freeexpansion and volume expansion as a direct index, and dry block saturation water absorptionas indirect index, and consider consider uniaxial compressive strength, the design of fourfactors and four levels of pilot programs. Conducted a total of16sets of different ratio test,has been micro-swell, weak-swell and strong-swell three different expansion of similarmaterial.Secondly, the water moisture test system were studied. The test system consists of waterand the probe tester two parts. Moisture probe with Al2O3as a humidity sensing material,copper is a common electrode and designer a concentric cylindrical structure. The probe ispart of RC composite element, the measurement range is5%to35%, the error value±3%,re-use rate (ceramic can be used1000times) can be used at low temperatures and other harshenvironments, has good adaptability.Tester is according to the amplifying circuit, usingSTM32as the control core, AD5933chip as the core test, designed32channel, can carry outreal-time testing and recording probe resistance capacitance value to32moisture probe. Afterthe inspection, test system composed of moisture probe and test instrument is safe and practical, stable test data and other good characteristics.Finally, neighborhood tunnel model test was conducted. Design two test scheme ofmodel test, a set of test in the test, a total of three sets of tests are carried out. In the model test,design the tunnel span is10.8meters, the arch high is8.5meters, this tunnel distance is5.5meters, buried depth of tunnel850meters. Model test using the similarity ratio is1:50, modelfiller using self-made expansion of similar material, and moisture probe into, to monitor themoisture content by tester. High stress influence behind construction and other factors, theinverted arch were considered in the experiment, conducted three model test, test results showthat the:Model of initial moisture content change rule of the internal model of water has a greatimpact, at high initial moisture content condition, permeability influence in under the weightof water is greater than the absorption capacity of similar material; in the low initial moisturecontent in surrounding rock excavation, water changes to intumescent material moisture, atthe same time showed infiltration and water volatile weak phenomenon..Bottom machine construction has the influence on the variation of water inside thetunnel invert, the longer the time lag, the bottom water of the longer range of surroundingrock, development in the internal moisture more widely. It is observed that the excavation ofthe tunnel in swelling rock in the inverted arch should be timely, reduce the water bottomtime.Humidity distribution of surrounding rock is reflected by the contour map of thesurrounding water. It can be found in the initial stage of water distribution is uniformity in thesurrounding humidity diagram. But at the bottom the stagnant period, is located in the tunnelon the internal moisture rock affected part of the smaller. While in the tunnel under internalwater part of the regional influence, usually there will be multiple agglomeration,agglomeration area first appeared in the excavation slope below the middle column below,along with the time development will form a large cluster region in the middle column. Acluster center, the area is enlarged, the center position of depression, and the water contentincreased. After the inverted arch construction is completed, agglomeration of regional waterwill slowly spread, the uniform distributed in rock mass. |
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