Applied Mechanics and Materials Vols. 353-356

Abstract: Constructing on the gob, especially the steep coal seam gob, will put the new buildings in jeopardy, because the gob and its overlying strata is already distorted and damaged with time passing away^[. In this paper, it takes the steep coal seam (75°) gob area in Xin Jiang province as the research object, and applies the theory of mining subsidence to analyze and evaluate the stability of the field, combining with the actual investigation. The result demonstrates that the mined-out area is in a state of instability and requires reinforcement^[2].

Abstract: The optimum shape of the tunnel is usually decided by many factors. Not only should it ensure the stability of surrounding rock and the advantageous of masonry's stress, but also it need to meet the using requirements of the cavern, the convenience of the construction, the least excavated volume and the best economic results. Seeking the optimal shapes of the carven which is under the specific condition has always been paid great attention by engineers. With the help of ADINA finite element analysis software, this paper imitates related data in elastic theory about the excavation of tunnels with the typical planes of fracture which are under the same geology condition. After that, it contrasts the actual computing results with the theoretical analysis, and then studies planes of fracture's optimal excavated shapes of the tunnels.

Abstract: As a single advanced geological prediction method has its adaptability and deficiency, it is hard to find unfavorable geological body comprehensively and accurately, so an integrated advance geological prediction system is proposed. The system divided the prediction process into three stages, which are long term prediction, medium term prediction and short term prediction. The three stages are complement and verification for each other to achieve a reliable geological prediction result. The system has been applied to a practical geological prediction of Doupengshan Tunnel on the high speed railway from Guiyang to Guangzhou of China. From the application, a finalized geological prediction result has been obtained, which suggests that the system can obtain a reliable geological prediction result.

Abstract: The safety response of joint rock underground tunnels is one of the many problems that draw the attention of geology specialists and scholars. Adopting two dimensional discrete element method, a numerical model of joint rock underground cavern is established to study its stability. The buried depth and the lateral pressure coefficient are considered respectively. The result shows: when the lateral pressure coefficient is identical, the depth is bigger the displacement is more bigger, and the displacement is strong influenced by the buried depth when the lateral pressure coefficient is big; In the same depth the tunnel is buried, the tunnel rocks displacement is slightly influenced by the lateral pressure coefficient when it is small, but the influence is seriously as the lateral pressure coefficient is big. The simulation in the context can be used to provide guide for joint rock tunnel excavation and supporting.

Abstract: The shallow underground tunnel is near to the ground; its many construction procedures are complicated, supporting and excavation are intertwined. The ground surface deformation is complex during construction. Through the analysis of the cross passage surface settlement data of Dalian metro Line 1High-tech zone Street station, we found that the ground surface caused by artificial filling integrally sinks during excavation, the shape of its sinking is like a flat funnel, the characteristics of settling tank are obvious. The influence of faces constructing is obvious on surface settlement, and the transverse influence range is about 30m; the longitudinal influence range is about 15m. The results of the paper show that the place of monitoring points should be held at 15m ahead from the tunnel face, effectivemonitoring period is 70d. The monitoring results are enough and safe for the stability requirement of the surrounding rock.

Abstract: It is study about crack diseases on tunnel lining of BEI JING metro, which is build by mining method. To begin with, the design information, the neighboring environment and the base characteristic of the tunnel is investigated. Meanwhile, the nondestructive test is working on the tunnel lining. On the basis of understanding all the disease forms, the reinforcing measure on tunnel lining is specifically formulated. This article mainly introduce the advantages and technical indicators of carbon fiber cloth, and the detailed construction technology of carbon fiber cloth in reinforcement of metro tunnel disease, that caused by local lining structure strength is not sufficient. This introduced reinforcement measures, which uses carbon fiber cloth in metro diseases could guide in the same engineering.

Abstract: Both of the stress field and deformation are unsymmetrical for shallow tunnel under unsymmetrical pressure and geological disaster such as collapse is easily to take place. This brings about troubling problems to both design and construction. In this paper, a case of Hongshigou tunnel is studied. Aiming at dealing with the problem of low buried and unsymmetrical pressure situation of tunnel entrance, a series of numerical studies has been done based on Flac^3D, after analyzing the characterization of stress field, displacement field and plastic zones, conclusions are gained as follows:1) 2) These conclusions can provide beneficial reference to design and construction for tunnel engineering.

Abstract: In order to study the ground surface settlement induced by shield tunneling, on the background of Xi'an metro line 2, this paper made use of the measured ground surface settlement to conduct characteristic parameters fitting of the settlement trough by Peck formula and the modified stiffness approach, proposed the initial suggestive value of the relevant calculation parameters, predicted the ground surface settlement by the formula with the determined parameters and compared the settlement with the actual settlement observation. The results show that the determination of the parameters is basicly right, the revised formula can be used to forecast ground surface settlement of Xi'an subway construction and finally a modified prediction formula is given.

Abstract: The performance of a tunnel is influenced by such factors as the size and shape of the opening, the in-situ stress and the deformation field and also properties of the rock mass. Different excavation procedures have great important influence on the stability of the surrounding rock, especially for tunnels under unsymmetrical pressure. In this paper, flac^3D is used in the simulation of different excavation sequence for Dawanggou tunnel in order to analyze the variation of plastic zones and deformation of the surrounding rock. The numerical results indicate that the mechanical index is different due to variant excavation plans and an optimized plan is determined based on the comprehensive analysis of the index gained from the simulation results.

Abstract: The effect of feet-lock bolt was studied in the rheological surrounding rock by numerical simulation. The results show: feet-lock bolt can improve the force state of vault, feet-lock bolt and grouting can improve the effect of vault stress state better in weak rock. After invert is applied, invert become the main load-bearing structure, the function of feet-lock bolt is greatly reduced after invert applied.