Advanced Materials Research Vols. 594-597

Abstract: To strengthen underground arch structure, the method with near-surface bonded carbon fiber reinforced polymer (CFRP) strips is proposed. A nonlinear finite element program is built to analyze concrete arch structure strengthened with CFRP. Factors that influence the strengthening effect are discussed. After arch strengthened with near-surface bonded CFRP strips, the cracking load, the yield load and the ultimate load has been greatly improved, the stiffness has also been greatly improved. The bearing capacity and the stiffness of arch structure increase with the layer quantity of CFRP increasing, increase with the strip quantity of CFRP in units increases. In the condition of the layer quantity and the strip quantity of CFRP being identical, the increasing ratio of load decreases with the reinforcement ratio increasing.

Abstract: The impacting effect of lithological features, tectonic stress, the mechanical parameters, structure surface contrasts were comparative analysis, to explore the effect from mentioned factors to surrounding rock-lining in schist tunnel. In order to make sure the dependence relationship of large deformation with these factors, the significant and interaction on large deformation in rock-mess and lining mechanical mechanism were studied according to the experiment data and statistics theory. The result shows that elastic modulus E, side pressure coefficient λ, and joint spacing S have obvious influence on the mechanical properties of surrounding rock-lining, and there is interaction among them. Furthermore, the influence of the interaction between S and λ to rock-lining is found to be significant, and there is an obviously dependent relationship between anchor failure and joints spacing. Therefore, when discussing the reduction measures to avoid the large deformation, the most appropriate method is to study it in overall factors and with the interaction.

Abstract: In first mine of Chagannaoer, 2# coal seam, the mainly mined out layer, was 22.00m thickness in average. In order to meet the requirements of production ability, the mine was planned to apply mining technology of fully mechanized caving. Good or bad of top coal’s caving was an important prerequisite which decided the mining technology of top coal caving could be chosen or not. Due to lack of producing mines in this region and no experience to refer, we simulated the mining process of 2# coal seam using numerical software of FLAC3D, and gained evolution laws of stress and displacement of top coal and overlying strata and expansion laws of plastic zone. Through analysis, we got that the top coal damaged seriously and the top coal could be caved smoothly. Relying on the geological conditions of site, we verified the simulated results with method of fuzzy comprehensive evaluation. Combined with the research results, we decided that 2# coal seam’s caving was better and was convenient for top coal caving, so it was suitable for caving mining in 2# coal seam in first mine of Chagannaoer.

Abstract: Finite element methods are adopted herein to study the group effect and sheltering effect in pile group during shield driven when the couple effect of vertical loads and soil displacement is considered. Results from the FEM show fine agreement with those from the Tianjin No.1 subway line project and the centrifuge tests carried out by Loganathan. Based on the finite element models, the effects of tunneling on pile groups are studied. The coefficients of settlement and lateral displacement are defined to assess the group effect and sheltering effect in pile groups with elevated cap.

Abstract: Under the mass of finite element analysis, the dynamic response characteristic and the influence law on lining mechanical of the existing disease tunnel which is influenced by newly built tunnel in process of construction are studied. The study shows that the cavities behind the lining have amplification effects on both the vibration speed and stress of the lining, which may induce structural failure of the lining structure; while superimposed effect between cavities has little effect on vibration speed, it has significant amplification effect on stress and leads to surging of additive tension stress; it is recommended that for the condition with more than one cavity, stress criterion should be introduced in as a complement. The study results can be applied to conducting the site monitoring and construction.

Abstract: The concept of design that people want to reduce disasters of highway engineering at the source location is gradually implemented. This article introduces the application of the Computer-aided Design (CAD) technology, Geographic Information System (GIS) technology and mathematical method under complicated environmental conditions in mountain areas. This template explains and demonstrates how to prepare your camera-ready paper for Trans Tech Publications. The best is to read these instructions and follow the outline of this text.

Abstract: CFG pile-net composite foundation has the advantages of small post construction settlement and uneven settlement, easy control of construction quality and fast construction speed. It`s widely used in subgrade engineering of high-speed railway. However, in coastal soft soil area, phenomena like breaking pile, collapsed embankment, cracking in embankment surface, undue settlement or convergence appeared in many places where railway CFG pile was improved during the foundation treatment, filling and preloading. Four numerical calculations were performed to investigate the failure pattern of CFG pile-net composite foundation with FLAC3D ( Fast Lagrangian Analysis of Continua, 3 dimensions) software. The paper describes four failure pattern, they are slip circle shear failure, pile tilt failure, roadbed sliding, soil sliding at pile end respectively through the analysis of the embankment and pile displacement as well as embankment deformation.

Abstract: Highway engineering quality is the lifeline of highway. Ground-penetrating radar is a new nondestructive testing technology of the road quality detection. This thesis takes advantage of ground-penetrating radar to analyze and discuss several related factors on highway nondestructive testing, for instance, the water content and compact degree of the base course, identification of cavity beneath the rigid pavement, and the differential settlement of the base course beneath the flexible pavement. Results of this research provide an excellent detection method for engineers and technicians.

Abstract: Highway in Yunnan Province, China, was known to suffer from local settlement due to the soft red soil foundations. This paper proposed cement-gravel piles to treat the settled foundations before paving the surface layer in highway repair and maintenance, in order to enhance the overall highway bearing capacity. Finite element software ANSYS was used to study the effect of cement-gravel piles on soft soil reinforcement and water reduction. The cement-gravel pile design parameters (9 to 10m for pile length, 1.2m to1.6m for pile spacing and 0.8m for pile diameter)are determined for different fill height, compactive effort and settlement magnitude. This research will provide helpful guidance to highway repair and maintenance of highway built in soft soil regions.

Abstract: In order to explore the durability of high bending strength pavement concrete, adding silica flour, fibrous reticulum, SD emulsion and HG emulsion separately in concrete mixture, the shrinkage characteristic, wear resistance and fatigue property of different high bending strength pavement concrete are tested, and contrastive analysis with the plain concrete material is researched. The test results show that the early contraction of HBSPC is bigger, but the total drying shrinkage strain is smaller than plain concrete, and the drying shrinkage stable stage of HBSPC is shorter than plain concrete. The temperature shrinkage of HBSPC and plain concrete is uniform basically, the temperature shrinkage coefficient of HBSPC is lower than the plain concrete in the negative warm area and warm area, but it is higher in 0 °C neighbor. The mixtures of the material enhance the wear resistance and fatigue property of concrete.