Advanced Materials Research Vols. 594-597

Abstract: By adopting dynamic time-history analysis method, the seismic analysis for the joint between intake tunnel and circumfluence groove is performed by FLAC3D. Aiming at the mechanical characteristics of this structure and rocky features, according to the design scheme, the analysis of seismic response is carried out, on the base of which envelopes of internal forces are given in this paper. The results show that change of the temperature has much influence on internal force in the same load effect combination. Temperature load also change the direction of internal force in some part. For the similar anti-seismic design, this paper has certain reference value and guiding sense.

Abstract: As an important urban rail transit, the metro has become one of the standards to measure whether the city belongs to modern internationalized destinations or not. Though the space of subway station is relatively small, the metro comprehensive pipeline is an important part of the subway station and includes a huge variety and quantity. During the design process of metro comprehensive pipelines, pipeline collision happens frequently. On Three-Dimensional design platform based on BIM technology, pipeline design has already been mature. This paper puts forward adjustment algorithms about metro comprehensive pipeline collision and they are both flexible and easy to realize and adapt to any Three-Dimensional platform based on BIM technology

Abstract: With the vigorous development of China's economic construction, especially since the western development, needs of traffic tunnel construction are increasing, a large number of tunnels will be built in the mountainous with deeply buried and high water pressure, it is an urgent problem about research on the groundwater environment and the ecological environment in the tunnel site area causes of tunnel construction. The Songpan County Mounigou tunnel located in the high altitude alpine region, regional and environmental geological conditions are complicated, the strata in the tunnel site area is aquifer, and developed faults fractures and fissures, tunnelling will lead to groundwater dewatering and cause the deterioration of the groundwater environment, Then great collapse, burst mud and water gushing will occur during the tunnel construction due to the enrichment of groundwater in tunnel site. Take a research on numerical simulation of groundwater flow in the tunnel site area, the tunnel excavation will form a larger catchment corridor, the impact is bound to the tunnel site hydrogeological conditions in the sphere of influence may appear to lower the groundwater level, seisensui drawdown or part of the dry, provide the basis for tunnel construction.

Abstract: Based on a project of subway constructed near elevated high speed railway, FEM method is adopted to analyze the effect of shield tunneling on the horizontal and vertical displacement of pile foundation of the viaduct as well as the pile caps on the condition that the nearest clear distance is 5m. The results show that with appropriate parameter control of shield tunneling, the effect of EPB shield tunneling on the displacement of piles in the three directions, i.e. horizontal displacement along and perpendicular to the longitudinal direction of the rail line and vertical displacement, is little. The same goes for the differential settlement between pile caps.

Abstract: For subway tunneling in urban underground, high safty of construction is needed.However, the safty and rationality of excavating plan are forecasted difficultly because of consealment. Based on the Zhang-Shen tunnel construction of Shenyang subway, bench method, single side-wall heading excavation method and CD excavation method are numerical simulated; according to the numerical calculation results and the constructing process, bench method is adopted; the ground settlement caused by excavation monitored during excavating is in the allowed range and the tunnel is safe during excavating.

Abstract: Compared with operated tunnel, one of the distinguishing features of a tunnel during construction is its single-ended geometry. The direction of fire smoke movement is the same as the direction for worker to evacuate the tunnel. This paper calculates fire-induced conditions, including temperature, smoke movement and visibility, which are influenced by two different ventilation systems. According to the simulation, when the fire located at bottom of tunnel, forced extraction is more effective; when the fire located at middle of tunnel, forced injection can protect workers in tunnel. Besides，increasing ventilation rate can control smoke spread effectively.

Abstract: Because of its large scale, long cycle and complex construction, the high speed railway tunnel construction exists many uncertain risk factors which are random and fuzzy, that makes it difficult to do quantitative analysis by general research methods. A synthetic evaluation index system for tunnel construction risk of high-speed railway is established by analyzing the factors that influence high-speed railway construction, and the analytic hierarchy process is used to determine the weight of each stage factor. Based on the hierarchy of each factor, a model of three-stage fuzzy synthetic evaluation is proposed, the fuzzy sets method is used to determine membership function, and risk ranking is also classified. The proposed method is applied to a Tian jiashan Tunnel construction of Shanghai-Kunming (Hu-Kun) high-speed railway. The analysis results show that the method is reasonable and practical, and it will be taken as an example by other similar projects.

Abstract: Foundation failure mode of high filling culverts involves calculation theory and method of subgrade bearing capacity, and it has great theoretical and practical values. After model of the culvert has been established, finite difference method will be used to do the numerical simulation in FLAC3D. Reaserch suggests that traditional Terzaghi/Meyerhof failure mode are not suitable for relatively deep buried subgrade of high filling culvert. Foundation failure of high filling culvert is caused by difference in stiffness and earth press, which result in settlement difference, and then forms subsidiary shear stress on the sliding surface. When stress value reaches shear strength of the foundation soil, shear failure occured.

Abstract: Tunnel excavating breaks the original hydrological dynamic balance, promotes water cycle and interchange, the influences extent to groundwater flow system and groundwater level by tunnel discharge has direct connection with structure of groundwater aquifer system. The factors which impact ecological environment including the depth of groundwater, groundwater mineralized degree, suspended moisture content and salt content etc., of which, Groundwater level is very important to the survival of vegetation. Analyzing tunnel’s water inflow and the change of seepage field impact the groundwater level, the change of surface water and groundwater quality and the ecological environment influence of nearby tunnel. Studying the water inflow of tunnel impact on the tunnel site, which provide a reference of correct implementation of the tunnel construction principles “prevention, drainage, cut, plug union, adaptation to local conditions, and comprehensive management of water” when build tunnel in similar geological conditions of landscape areas.

Abstract: Tunnel excavation breaks the original hydrological dynamic balance, promotes water cycle and influences the mountain groundwater system to some extent. Water inflow during construction not only threatens construction safety, but also affects surface vegetation’s growth. Taking tunnel 1 in Chongqing Cimushan area as the project background, and through analyzing the hydrological test results from tunnel exploration stage, counting the actual water inflow quantity in construction period, doing the 3-D finite element numerical modeling, we analyzed and evaluated the tunnel water inflow quantity, to provide reference for recognizing the harm of groundwater and making treatment measures.