Applied Mechanics and Materials Vols. 170-173

Abstract: According to the engineering geological and hydrogeological condition of loess tunnel with large transection in the expressway from Datong to Hunyuan, and on the basis of the planned running speed of motorized vehicles in the loess tunnel, the excogitative parameters of tunnel support for relevant surrounding rock and its driving method have been put forth in this paper. The application of the presented new construction method for expressway loess tunnel has accomplished a great success.

Abstract: Through the general finite element program ANSYS to model the segment joints of Tianjin Metro shield tunnel. The relation between rotational angle and bending moment of a segment joint were investigated, and the numerical value of flexural rigidity is obtained by fitting method. In addition, the varying law of flexural rigidity is influenced by eccentricity is discussed.

Abstract: The energy release and depressurization method is often used for the hidden cavity with extra big mass and high pressure in a tunnel. It is critical to determine the minimal depth of safe overburden for the release hole at lower position and the pressure at high position to be released. According to actual data collected from a cavity of Maluqing tunnel of Hubei, this paper performs the computer simulation and analysis for the safety of the release hole at lower position in the cavity and determines the critical safe depth to disclose the cavity is determined tentatively by using the finite differential software of FLAC3D. The simulated results in accord well with the actual situation show the rationality and validity of this numerical simulation.

Abstract: In the design of underground engineering analogy, the division of rock mass level and the selection of support parameters are affected by many uncertain factors which share characteristics of random and obscurity. This paper lays the foundation of the classification of joint rock masses CSIR and supporting parameters recommended values, selecting several key factors affecting the stability of surrounding rock masses, and employing the methods of fuzzy comprehensive evaluation to divide the underground cavern, and having put forward the reasonable supporting parameters. The results show that the level of surrounding rock is the Ⅲ, meanwhile, it takes into account the proximity effects and designs the supporting parameters to the supports, as a result, this method has achieved comparatively reasonable and economic effects in the practical application.

Abstract: Through the Comparisons of tunnel greenhouse for the carrying snow loading capacity under the different mode of transfer force, some conclusions are summed up: different mode of transfer force has much influence upon the carrying capacity under the same snow loading. The unite of structure scheme to whole-part should be thought much in the structure design for greenhouse according to the principle of equal strength. The results indicate that the structure of east-china type multi-span tunnel plastic greenhouse is rational, and has fine mechanics properties.

Abstract: The surrounding rock stress field monitor has been done in excavation by vibrating wire transducer. The field monitoring data are compared with numerical simulation results. The result shows: Vibrating wire transducer can record the stress variation of surrounding rock and support. Surrounding rock stress changes violently at every excavation step, such as lower bench excavation, the stress variation is mainly controlled by the spatial effect. When the distance from excavation face to the monitoring section is more than a tunnel diameter, the rock stress variation is mainly affected by time and it is relatively smooth and continuous.

Abstract: Seepage is one of the unfavorable factors inducing construction accident. It is essential to analyze the influence to the displacement from seepage by the variety of the parameter of seepage. Set up simulation model by software Abaqus. This text studied the law on the displacement of groundwater during construction considering the influence of groundwater seepage, and contrasted the simulation data with groundwater and without groundwater. The pore water pressure changes because of the influence to seepage field from excavation. the displacement curves head for the same on different porosity. The settlement increase and the swell decrease with the addition of porosity. It is obvious that the displacement with groundwater is lager than without groundwater. A suggestion is made that the tunnel engineering should be designed with considering the influence of groundwater.

Abstract: To reduce the impact on water resource and the environment, the ‘controlled drainage principle’ is complied with when designing waterproof and drainage system of tunnel in recent years. For deep tunnel in Water-soaked Karst Stratum, the lining would sustain high water pressure that was caused by the unreasonable design of waterproof and drainage system. Taking a railway shield tunnel as an engineering background, the water shut-off effect of grouting circle, minimum controlled discharge of tunnel and the water pressure of lining properties were studied. The results indicated that, under the condition of high initial water pressure and adequate groundwater recharge, to achieve the desired water shut-off effect, the permeability coefficient of grouting circle should be less than that of surrounding rock over one quantitative grade; the water pressure of lining decreased with the increase of discharge, and showed a linear relationship; the lining could meet the requirement on the design water pressure load, when the permeability coefficient of grouting circle less than 1/20 of the surrounding rock’s, and the controlled discharge greater than or equal 1/2 of uncontrolled discharge; the full-sealing waterproof lining would sustain initial water pressure and the calculation value of water pressure couldn’t be discounted, if the grouting wasn’t waterproof.

Abstract: Self-walking tunneling is at present the most advanced technology to underground pipeline construction. One of the difficulties is orientation measuring technology, that involves if tunneling can keep along with designed line. There is no mature method for self-walking tunnelling. This paper, based on the eleventh five-year plan national science and technology subject, comprehensive utilization of total station and rangefinder and combination with the characteristics of the tunneller, researches a set of practical and low cost measurement method. The application shows that the method meets with the need of orientation measurement to curve tunneling.

Abstract: For a different supporting time hole into subway tunnel excavation, with the initial stress in the surrounding rock in the tunnel and initial stress reverse impose the same release the equivalent of the simulation node, consider themselves lining load conditions in a hole under the formation of linear elastic numerical solution. The analysis indicated that with the increasing of the stress release rate, the hole arch displacement gradually decrease. When the stress release rate is bigger than a value, the hole arch displacement is increase rapidly, this is a marginal value (the biggest permission release rate); Under the identical hole diameter condition, the burying depth is bigger, the biggest permission release rate is bigger; Under the identical burying depth condition, the hole diameter is bigger, the biggest permission release rate is smaller.