Applied Mechanics and Materials Vols. 204-208

Abstract: Based on Huolangyu tunnel of Mixing road, this paper researches the monitoring of ground surface vibration and the technology of controlled blasting. Monitoring and analysis results show: The ground surface vibration decline from constructed position to un-constructed position along tunnel excavation direction. The maximum ground surface vibration locates at the shallow position along tunnel cross section. The surface vibration velocity main vibration frequency has more than one advantage frequency, main vibration frequency concentration distribution in 20～40Hz low frequency band. Tunnel driving, the emphasis of the blasting vibration should focus on control of tunnel excavation area has the upper, lining structure and shallow buried in the influence of the surrounding rock; Tunnel through the surface buildings, cannot ignore already forming of blasting seismic effects of tunnel amplification and resonance effect.

Abstract: According to a real project of Jiaozhou Bay subsea tunnel, the effect of grouting circle on the seepage field was discussed. The calculation results showed that the principle of "to block mainly, to emit limitedly" should be taken in the waterproofing and drainage of subsea tunnel. If the grouting circle effect was used on the condition of the same effect of water plugging, the thinner the thickness of grouting circle and the smaller permeability coefficient of grouting circle required. The role of grouting circle was that decreasing the gushing water quantity by means of blocking the seepage paths of groundwater, so as to achieve a smaller discharge could significantly reduce the external water pressure of lining. When the tunnel gushing water quantity was equal to the control discharge, it was considered as free drainage and the lining could not bear the water pressure.

Abstract: Recently, more and more shield-driven construction projects have to cross over or under the existing metro line in soft soil in China. To evaluate the influence of such construction, three major factors were studied in this article based on monitoring data. They were the vertical interval between the two tunnels, the projection angel and the synchronous grouting rate. The linear regression formulas were also obtained to show the trends of displacement during the overcrossing and the undercrossing construction projects.

Abstract: During the construction of Tongluoshan Tunnel of the 6th light rail line in Chongqing, collapse of goaf of colliery area occurred which affects the construction and permanent safety heavily. Advanced geological prediction were done with ground penetrating radar to probe the goaf’s location, scale and characters of underground water and filling articles, then countermeasures such as advanced pipe roof supporting, goaf stowing, wall rock and filling articles’ voids grouting was applied；after that，supporting plan was adjusted to ensure construction safety with the data from monitoring whose result proves the availability of above prediction technology and countermeasures to similar goaf.

Abstract: According to inspection and assessment technology and method for the ground masonry structure, this paper presents the inspection method and results for an electric cable tunnel with masonry structure. The contents of the inspection include masonry bricks strength grading, masonry mortars strength grading, concrete strength for crest slab, reinforcement of crest slab and appearance of masonry structure. And the technologies for identification are introduced. Therefore, the key problems for safety inspection of electric cable tunnel with masonry structure are solved. The inspection items, process and identification technologies presented in this paper are effective and applicable for electric cable tunnel with masonry structure.

Abstract: A three-dimensional numerical analysis was conducted to investigate the effects of a new shield tunnel excavation on the internal forces and deformation induced in an existing parallel tunnel and soil plastic zones around it. Special attention was paid to the influence of relative positions between two tunnels. The results of the analysis show that the relative positions affect the mechanical behavior of the existing parallel tunnel and the soil mass behavior around it. When a new tunnel is driven below or above an existing parallel tunnel, important increments are induced in deformation and bending moment in the lining of existing tunnel at its crown and springline, compared to that of induced by new tunnel excavation in horizontally parallel to the existing one. The plastic zones around tunnels also extend larger when tunnels are driven in vertically parallel than they are in horizontally parallel. For the safety concern, it is concluded that horizontally parallel configuration model between two tunnels should be adopted in practice.

Abstract: The method combining the construction survey and the numerical simulation is proposed in the paper to accurately obtain the deformation of the slurry shield construction under across and parallel existing tunnel. The surface settlements of the engineering construction initial position are surveyed. The reliability of the three dimensional finite element models is verified by comparing with the survey results. The deformation variation of the existing tunnel and ground surface are obtained by the elastoplasticity nonlinear calculations, showing the feasibility and effectiveness of the proposed method and the credibility and accuracy of the calculated results. Meanwhile, the measures of control deformation are presented. The surveyed settlements after the construction process of implementing measures are smaller than those calculated, indicating the effect obviously of the measures which has practical significance.

Abstract: Based on the actual geological data of the 1202 lower layer work face of the Zhong Xing mine, in Shanxi province, a physical similar simulation model has been built to analyze the influence on the lower coal layer after mining the upper layer, and research on the deformation, failure law and the stress distribution of overburden rock. The results show that after mining the upper coal layer, overburden rock experienced subsidence, separation, bending and even breaking down, and the original state of the rock destroyed. The rock's intensity is weaken, and the whole rock has been softened. When the distance of the coal layers becomes smaller, the influence of the mutual exploitation becomes larger. Those results provide a reference for reasonable layout of the mining of the coal seam working face.

Abstract: The technology of shield has been widely used in city subway design, when the shield tunnel encounters a bridge across the river; the key issue is to complete the pile foundation underpinning according to the diverse geological conditions. With an example of subway Shield tunnel project from Xi’an, The paper presents the working procedure and emphases of pile foundation underpinning.Based on the configuration design, both the load beared by one single stake and the distortion of the joists are calculated, the carrying capacity computations indicate that pile foundation underpinning is feasible.

Abstract: The long-term uneven settlement may cause the pipe structure cracking, leakage or even serious damage during the operation of the immersed tunnel. Settlement control measures of immersed tunnel were generalized from design-construction-operation three stages as the time order, and the control measures in the construction stage was particular emphasized. The treatment methods of the base layer were reclassified into compact the base, replace the base and pile base three types and relative project cases were enumerated. Contrary to the shortage of present stage, control measures and suggestion that fit soft base were raised after compare.