Papers by Author: Gang Wei

Abstract: This study simulated the condition of below-wall raft foundation supported masonry structure perpendicularly penetrated by shallow-buried and mining tunnelling using 3D MIDAS/GTS software with consideration of the coaction of structure, ground and tunnel. The load and deformation patterns of structure before and after the penetration of tunnelling excavation face were evaluated. Results from the study showed that: when the horizontal distance between the central axis of the structure and the axis of the tunnel L=0 m, the settlement of the structure increased before and after the penetration of tunnel through the masonry structure, and the settlement became stable after the tunnel passed through a certain distance (approximately 2.4 times of the thickness of ground cover); the structure settled overall and the difference of settlement was relatively small; the maximum first principal stress P₁ and the maximum deformation rate E₁ showed an overall increasing trend. With the increase of L from 0, inclination of the structure towards the tunnel was witnessed, the settlement of foundation appeared to be linearly distributed and the inclination rate of foundation first increased then reduced; P₁ showed a decreasing trend and E₁ first reduced, then increased and decreased again.

Abstract: During the shallow-buried tunnel excavation, the formation will be affected and the nearby buildings will be caused fracture. By using three dimensional software MIDAS/GTS, the interactions among structures-soil-tunnel system is considered in this paper, and the working condition of shallow-buried underground excavation is simulated in the independent foundation of frame structures. It is indicated that building will tilt to the side of tunnel as the horizontal distance L between building and tunnels is increasing, after reaching certain distance, the influence to the building tends to little, at the same time, the maximum first principal stress P₁ and maximum deformation rate E₁ show a trend of decrease. When the kind of soil is worse, the settlement and non-uniform settlement of buildings increase, meanwhile P₁ and E₁ increase. With the increasing story of the framework, the settlement of building is nearly not affected, and P₁ and E₁ decrease slightly.

Abstract: In the background of a foundation pit excavation project on Yanan Road in Hangzhou City, this study simulated the excavation of foundation pit above an underground tunnel using 3D MIDAS/GTS software. The combined action of foundation pit, ground and tunnel were considered. The influence of foundation pit excavation on the deformation of underlain shield tunnel was evaluated and simulations were carried out on the effectiveness of different strengthening and control approaches. Results from the research showed that during the stages of piling and ground strengthening, settlement occurred at the tunnel; with the excavation of foundation pit, uplift deformation at the bottom of the foundation pit and the tunnel increased; with stricter strengthening and control techniques employed, the magnitude of uplift at the tunnel and bottom of the foundation pit reduced, suggesting that various control procedures were effective to some extent.

Abstract: The immersed tube tunnels in Yangtze river delta region are affected severely by back-silting. Back-silting is difficult to control during construction and the consequences are hard to evaluate as well. In this study, sedimentation experiment was conducted incorporating back-silting soil solutions with different concentration ratios, and compression tests on the initial sedimentation layers was also conducted based on back-silting soil specimens taken from the back-silting soil sedimentary layers located in the surrounding area of Shenjiamen harbor undersea immersed tube tunnel in Zhoushan City. The undersea back-silting was assessed from the aspect of sedimentation speed and the strength of initial sedimentary layers. Results from the study are essential for further study of back-silting load and the effect of back-silting on settlement.

Abstract: The settlement of immersed tube tunnel is mainly caused by the compression of basal layer and recompression of the ground foundation layer. Defining the composite foundation as a combination of basal layer ofimmerse tube tunnel and ground foundation layer, a three-parameter model is proposed in this study to simulate the composite foundation in which the basal layer was represented using springs and the ground foundation layer by Kelvin’s model. Based on the solution of beam on elastic foundation, analytical solution for settlement of immersed tube tunnel using the proposed three-parameter model was derived by means of Laplace transformation according to the correspondence principle and the constitutional relationship of the three-parameter model. Initial and final settlement as well as variation of settlement in terms of time were calculated and compared with the actual measured data in combination with actual data measured during tunnelling of Shenjiamen immersed tube tunnel in Zhoushan City. Results showed that the proposed three-parameter model is capable of replacing the basal and ground foundation layers. The calculated value matched favourably with the actual measured value and the variation of settlement in terms of time for immerse tube tunnel can be represented.

Abstract: The construction method for immerse tube tunnelling varies significantly in sites with different hydrogeological conditions. Using the construction process of the undersea immerse tunnel at Shenjiamen harbour, Zhoushan city, Zhejiang Province as an example, the overall construction process of undocking, float transporting, immerse positioning, locking, grouting and backfilling were introduced in this study, with possible problems at each stage listed in details. The problems occurred when grouting Tube E1, E2 and E3 (floating or settling) and relevant solutions were concluded and the related possible causes were analysed.

Abstract: t is significant to study settlement characteristics of the base layer in immersed tube tunnel for the settlement is quite large during the construction. Collects trial data of five sand replacement model based on engineering of Guangzhou zhujiang immersed tube tunnel, Guangzhou biological island-University city immersed tube tunnel, Guangzhou Zhoutouzui variable cross-section immersed tube tunnel, Tianjin Haihe immersed tube tunnel and Zhoushan shenjiamen immersed tube tunnel. Analyzes current study of the sand replacement model test and settlement characteristics, and summarizes current development and research progress. Analyzing the mechanism of settlement and silting impact in the base layer anti to the lack of settlement characteristic study and puts the further study and research ideas forward.

Abstract: Urban tunnels mainly include subway tunnels, street-passage tunnels and underground road tunnels etc. With the development and utilization of underground space, urban tunnels have developed rapidly in recent years. At the same time, development of urban tunnels faces new opportunities. However, related professionals are not sufficient to make it come true. This thesis discusses feasibility of establishing ‘Urban Tunnels’ in the major Civil Engineering, including employment situation of Civil Engineering, integration with the demands of Zhejiang Province and Hangzhou City, misplaced development with other colleges and universities and the features of students majoring in civil engineering. Besides, it makes sufficient preparation in aspects of hardware, software, teachers and social support, which makes the construction of new major be implemented successfully according to plans and steps.

Abstract: Pit excavation has a negative impact on the existing shield tunnel close to it. The deformation mechanism of the existing tunnel during the pit excavation was analyzed. Theoretical analysis results shows: excavation unloading decreases the pressure in horizontal direction of the tunnel, which causes tunnel taking the horizontal displacement to the pit side; convergent deformation keeps in horizontal stretching, vertical compression, but the deformation is aggravated; tunnel vertical uplift or settlement is determined by the pit excavation depth; precipitation would make tunnel sinking. Five domestic pit excavation engineering instance was collected, and the reliability of the analysis in this article is proved by the statistical analysis of the measured data.

Abstract: The settlement of immersed tube tunnel may be influenced by variety factors in construction, operation and loads. The factors causing the immersed tube tunnel settlement were summarized and described in-depth by cases and data. Combined the mechanism analysis with the construction process, the action time of different loads along the construction process is summarized, the consolidation characteristics and settlement mechanism of original state soil layer and base layer are analyzed. The mechanisms and variations of tidal loading, siltation and dredging disturbance, groundwater level drawdown are elaborated.