Applied Mechanics and Materials Vols. 501-504

Abstract: Depended on the fact that so many plans for tunnel design laid much emphasis on its construction process and its short-term cost while ignored the increasing importance of environment now, this article puts forward a synthetical method contains analytic hierarchy process and fuzzy mathematics to evaluate plans for tunnel design with certain indexes including the volume of earth works, carbon emissions, energy consumption and consumption of materials, all of which were taken from the main procedures of the tunnel constrution. In the synthetical evaluation process, the performance on environment of a construction plan was graded into four levels, after the probabilities of four indexes may have on each level was obtained, often by investigation or experience, the final scores of the designs could be calculated with the fuzzy probability method. Further, the designs could be compared.

Abstract: Analyzing and Evaluating the stability of the surrounding rock is an indispensable and important part in the tunnel design. In this paper, the surrounding rock stability of Danba hydropower station diversion tunnel is dealt with, FLAC3Dsoftware is used for stability analysis. Selecting three different cross sections for calculation models, comparing with the displacement and principal stress and the plastic zone which calculated by FLAC3D, we can evaluate their stability and get the best diversion tunnel design.

Abstract: Combined with the current research situation of construction of tunnels with small clear spacing, the key technology of design and construction of tunnels with small clear spacing is summarized, which primarily consists of rational clear interval of tunnels with small clear spacing, advanced support, construction methods and clip rock reinforcement. The passage describes various methods of key technologies currently in use and the selecting rule under the condition of various categories of surrounding rocks, which has some significance on the safe construction of tunnels with small clear spacing.

Abstract: Parameters monitoring and risk management is more and more important and necessary for Tunnel Boring Machine (TBM) along with strata and environmental conditions are becoming increasingly complex. The accurate and real-time monitoring of TBM construction process is the basis of security for structure, environment and avoiding the engineering accidents. However, almost all existing TBMs only have the functions of data collecting and storing, how to use these data to monitor and evaluate the status of TBM advancing in real-time, as well as realize the functions of risk prediction and management are still a continuous research problems. In this paper, Risk Monitoring System for Tunnel Boring Machine (RMSTC) has been researched and developed to monitor the process of TBM tunneling and manage the construction risks. The engineering practices show that the RMSTC is a safe and credible system which can achieve data transmission, parameters analysis and material consumption statistics in real-time, and it offers a new efficient way for risk recognition, analysis, evaluation, prediction and control.

Abstract: This paper introduces a three-dimensional numerical model of simulating the tunneling cycle of tunnel-type anchorage by the large finite element software ABAQUS. With tunneling cycles, the space-time effect for footage is analyzed comparatively, which are between the tunnel in headings and tunnel in foots. There are three parameters for evaluating the construction methods, that contain vertical displacement of tunnel vault, vertical displacement of tunnel invert, and horizontal displacement of tunnel wall. The results show that all the values of the above parameters are in the control. Hence, the construction methods of the engineering are available.

Abstract: The numerical simulation method of safe distance between concealed karst cave and tunnel based on shear strength reduction method safety factor catastrophe is proposed. The safety factor of different distance between concealed karst cave and tunnel can be obtained using strength reduction finite element method numerical calculation with the finite element solution non convergence as the standard rock damage, then compare the safety factor of different distance, the catastrophe of safety factor corresponding to the distance is the safe distance between concealed karst cave and tunnel, and the plastic zone of rock stratum between concealed karst cave and tunnel is reaching run-through state, which is verified by engineering example.

Abstract: This is accomplished by a variety of indoor rock mechanics experiments and experimental sound emission, taking Chengde area of Hebei Province the tunnel rock made of rock as research object to simulate various loading rock failure process. To analysis the data obtained of acoustic emission and Dynamics in the process obtaining the characteristic parameters of rock failure process in order to Monitor and Forecast. Through the three axial compression test and the process of acoustic emission signal acquisition discussed the relation between the mechanical parameters of rock acoustic emission parameters of stress. The characteristic parameters of acoustic emission signals with stress and time change through analyzing the acoustic Emission characteristics of each stage in the process of rock failure provide the basis for the prediction of rock burst.

Abstract: The marine sedimentary strata are spread in coastal area of Tianjin. Due to low soil strength, high underground water level and strong soil plasticity flow, instability accidents happened frequently in soft soil area. In the foundation excavation of underground station, because of stress release and change in ground water level, the differential settlement of surrounding buildings, ground crack and deformation of underground pipeline will happen. The stability of surrounding rocks in the foundation excavation of underground station has been calculated and analyzed by using numerical simulation method. The Surrounding soil deformation of foundation pit has been gotten to analyze.

Abstract: Gaoligong Mountain tunnel is the key project in the Dali-Ruili Railway. In order to optimize the design and guide construction, In-situ stress has been conducted in five boreholes using hydraulic fracturing method, the current shallow crustal in-situ stress state at the project area are obtained according to the measurements results, and deep in-situ stress is predicted using lateral pressure coefficient. The test results show that at depths ranging from 299-979m, the maximum horizontal principal stress is 5.33-30.12Mpa, the minimum horizontal principal stress is 4.94-23.11Mpa, the horizontal principal stress reach 30Mpa at maximum the depth of burial, indicating that the engineering stress filed is dominated by horizontal stress. Based on the In-situ stress data and different distinguish methods, rockburst and large deformation are predicted. The results show that In-situ stress magnitude in this area is classified as high level, and the direction of the maximum horizontal stress is NEE, In-situ stress orientation is conductive to stable of the tunnel. When the tunnel passes through the deep-burial and hard rock, the wall rock may happen rockburst; and the large deformation may happen when the tunnel pass through the weak rock. In order to avoid the disadvantage conditions, reasonable excavation method and safety support method should be adopted during tunnel excavating.

Abstract: On the basis of analyzing recent years research achievement of similitude material, we adopt cement, gypsum, blanc fixe and water to perform matching experiment. Orthogonal test has been used in this experiment. From the calculating data, it can be received that density, elasticity modulus and ultimate compressive strength in different specimens. Meanwhile, the relationship between elasticity modulus, ultimate compressive strength and the proportion of each composition is obtained. The results show that the similitude material is recognized to satisfy actual tunnel lining properties such as elasticity modulus and ultimate compressive strength .