Abstract: In this work, research was carried out based on the shield tunnel of metro line 1 in Hangzhou. The construction of this tunnel beneath the sewage pipelines, which have large diameter with water pressure. The project studied in this treatise is relatively rare in China in terms of sewer pipes, the number of sewers, spacing between shield and sewers and the crossing times. A numerical model was established to analyze the construction of metro across the sewage pipelines with water pressure, taking the interactions between tunnel, pipelines and soil into account. The stress of pipelines, settlement of pipelines and ground during the crossing process were calculated. The finite element results were compared with measured results to verify the reliability of numerical results. Some meaningful results were achieved.
Abstract: The monitoring is important to keep tunnel engineering construction stability. But, regular monitoring means cannot detect the position of the rock which has much stress accurately, accordingly, cannot monitor the influence of the construction process. In order to detect the local surrounding rock cracking due to excavation, a new method named micro-seismic monitoring is proposed to identify the elastic wave of rock bursting. Micro-seismic monitoring technology can find the bursting position by use the elastic wave of the rock, then, it can make an evaluation about the stability of the rock. In the method, using several sensors monitoring data of elastic wave identifies the bursting location. Then, the stability of the rock is analyzed and tunnel support parameters are optimized. At last, the method is used to monitor the Yuanyanghui tunnel located in Shanxi Province, China. The monitoring results identified the relatively stable and relatively unstable area. In-situ measurements on the surrounding rock have been used in the two areas, and therefore we use the analysis results to improve the initial tunnel support parameters.
Abstract: At present, smooth blasting are widely used in urban subway excavation. To improve smooth blasting effect in the blasting excavation process of urban subway, this paper took the fourteen section of Qingdao subway as the background, confirmed the reasonable interval of surrounding holes by combining the theoretical calculation and the actual scene; improved the smooth blasting effect obviously by changing the charge structure of periphery holes. The results of the experiment showed that adopted air-deck divided decoupling charge, when interval of surrounding holes was 350mm, and the minimum burden was 500mm, the smooth blasting effect was better, and the half eye tracking rate was beyond 85%, which meet the design requirements. The experiments proved that when adopted air-deck divided decoupling charge, the blasting effect was better than adopted concentrated charge, so there will be some reference value to the later engineering.
Abstract: While the tunnel crossing the ancient Great Wall, we must take effective measures to control ground deformation, prevent ground deformation is too large, destroying the heritage. In order to study the effects of tunnel excavation types on strata deformation, a three-dimensional computational model is built to simulate surface settlement and horizontal displacement by three different excavation types which are both-side heading method, CRD method, and hole pile method. Following comparative analysis, in line with the realistic program is recommended. The results show that both-side heading method can better control the surface deformation, and has a high efficiency of construction, which was selected as the construction scheme of tunnel crossing the ancient great wall. The results of this study are expected to provide construction experience to the works of a similar background.
Abstract: Through model tests, three different locations of the interface of the soil and rock in sandy soil tunnel were simulated. The failure processes of the face and the un-supported section were described. The initial and finial depth-width ratios were obtained. The failure features and mechanism were analyzed. The tests show that the longitudinal equilibrium arch in the un-supported section fist forms, and then the tunnel face damages. The failure surface shape approximates to logarithm spire curve, and it is the interface of the soil and rock when there is the interface of the soil and rock in front of the tunnel face. The interface of the soil and rock improves the stability and the depth-width ratios of the tunnel face and the un-supported section, especially when it is in front of the tunnel face.
Abstract: Ground fissure is a kind of serious geological disaster. There will be more unprecedented challenges during the construction of the urban subway in ground fissures-developed zone. How to ensure the long-term operation safety of the subway crossing ground fissure belts are the first problems for the subway under construction in the cities with ground fissure developed. One of the important problems is that dynamic interaction and disaster effect control among ground fissure-stratum-subway tunnel under subway dynamic loading, which is also the important problem to be solved in the engineering. This problem involves the following three aspects: (a) the determination of subway dynamic loading; (b) the structure dynamic response of subway tunnel; (c) the interaction among stratum-ground fissure-subway tunnel. According to make a comment on these researches, some issues which are necessary to carry out in this field are suggested.
Abstract: The foreign precision monitoring equipment was used for long term health monitoring in the large diameter tunnel of Hangzhou Qingchun-road. Based on field monitoring data, the force and deformation of the large section crossing-river tunnel during operation period were summarized and analyzed. A detailed analysis of the effect of tide and scour on the tunnel interface force and tunnel settlement were given. Data shows accumulations of both longitudinal settlement of tunnel segments and the earth pressure distribution around the tunnel lining under the loads of both traffic and tide which results in soil disturbance in the construction period. The settlement becomes stable after about six months. The substratum has a great influence on the longitudinal settlement of tunnel segments. The settlement of tunnel invert in sandy substratum is obviously affected by the tide of Qiantang River for short time, while slight changes appear in the deformation of tunnel diameter, stress of steel bar and earth pressure distribution.
Abstract: In order to analyze the damping effect of high-elastic damping fastener on rail transit viaduct, Ls Dyna software was use to analyze rail and viaduct vertical vibration under different fastener damping constant. Fasteners with no damping constant and different damping constant are built in finite element model with rail transit viaduct, and the acceleration simulation results of them are compared to find damping effect on rail transit viaduct vibration transmission. The results indicate that the damping characteristic can attenuate vibration produced by wheel rail impact, however as the fastener damping constant are only parts of the whole damping system of the rail transit viaduct, the damping constant is not as better as its increment. The paper attempts to provide advice for employment of damping fastener in excessive vibration region of urban mass transit.
Abstract: South tower of Taizhou bridge is located in complex hydrogeological conditions,the amount of its excavation engineering is large.Combined with the successful application of locking steel pipe pile cofferdam in the south tower project of Taizhou Yangtze Highway Bridge,from comparison and demonstration, scheme design and construction, process monitoring to introduce locking steel pipe pile cofferdam in detail,using the classical method and the M method to design and calculation for supporting structure.Construction practice shows that the design and calculation of support structure is accurate,locking steel pipe pile fully played its function of sealing,it also has great rigidity, good integrity strong bending resistance and other advantages.The successfully application of this technology,promoting the technological progress of bridge foundation constructionthe in deep water or complex geological conditions,it provides a basis for the construction of similar projects in the future.
Abstract: This paper mainly discusses a method based on Wi-Fi network technology cluster bridge safety monitoring system. In bridge safety monitoring center can be displayed at the same time, analysis of many bridge safety monitoring status, is convenient for decision makers to different budgets, optimize regional bridge within cluster maintenance; through the cluster type bridge safety monitoring, can be realized on the spread over a larger area of bridge security state data comparison, unified management, completely changed the previous single bridge safety monitoring system to realize the information sharing between the" information island" situation, more convenient to the regional environment, similar to different bridge structure or different environment, similar to bridge structure safety status of the longitudinal, transverse analysis comparison and research, which is beneficial to promote the optimum design of bridge structure, and based on the bridge maintenance and reinforcement.