Papers by Keyword: Deep Excavation

Abstract: High filling and excavation of loess landslide happens more frequently, which serious impact on security of the project, but formation mechanism of the landslide is still not perfect, therefore this paper analyze from damage characteristics and influence factors of slope stability to evaluate its stability and summary such failure mode. Conclusion: ① The root cause of the formation of class landslide: the lithology of compacted layer is different from upper loose soil, and the clay is unevenly distributed, which lead to local shear strength lower ② Rainfall is the main predisposing factors of slope instability, which infiltrates slope, the weak surface throughout the entire slope.③ Failure mode is similar to the general loess landslide, but the position of slipping surface is more regular

Abstract: A deep excavation in Hefei is proposed in this paper. Some useful conclusions are drawn through the analysis of the measured results including displacement of retaining structure, axial force of horizontal support and settlement of the surrounding buildings. It is useful for design, construction of similar engineering.

Abstract: According to the engineering characteristics,the project was divided into four typical operating conditions,the deformation rules of deep foundation pit at subway station in tunneling are studied with the method of FLAC3D numerical simulation,the supporting structures choose by the bored piles and interior support. The analysis of the horizontal deformation of the retaining structures,the axial force changes of steel support,the settlement law and the influence sphere of surrounding soil. For installation of prop structures on the performance of deep excavations is investigated through numerical analysis with site specific subsurface conditions,The conclusion in this paper can provides reference for the reasonable design and safety construction of deep foundation pit.

Abstract: Mechanisms of the distortion of deep excavation in soft clay are recommended on the beginning. Plane FEA method is combined with back-analysis from displacement on this paper to establish a dynamic prediction system of the distortion of deep excavation, which is proved to be viable by practice. Combining with the idea of process control, a process control model of the distortion of deep excavation is established on this paper. It is divided into three parts: advance control, observation and dynamic prediction, process control in the construction.

Abstract: Based on the oversize deep excavation project of Wangjing Soho in Beijing, the stress monitoring of top beam, soldier piles and anchor strand were carried out, which shows the development process of the internal force caused by spatial member interaction, reflect the differences from the mechanics principal of the traditional design method such as elastic foundation beam or equivalence beam of limit equilibrium state. Monitoring practice reveals that soldier pile were under the combination state of compression and bending, and are proved safe because of low stress; while the top coupled beam is under the combination state of tension and bending, and the tensile stress might goes to the stress limit, which has much relationship to the anchor arrangement, so the design of top beam should be regarded as one of the key control of construction safety. The tensile force of anchor strand are not easy to be hold with the tapered-type anchorage in site, the actual tested tensile force reaches 150~220KN , only the half of the design value.

Abstract: In the northeast of China,the research of subway foundation pit is still infancy,which needs enriching. This paper relies on the deep foundation pit engineering of Xiashengou Subway Station in Shenyang. Through the analysis of deformation foundation pits to study deformation characteristics.Through the monitoring data,we can know that combined the bored and steel support the deformation of the retaining structure and the ground surface subsidence can be well controlled.The deformation of the envelope and the surface has a strong time effect and increases with time,in the excavation stage,pile deformation presented randomness. In the excavation stage, pile deformation presented randomness.When the excavation completed 45 days,from the top of the pile to the pile at 13m depth,the lateral volume is almost equal, and thus down to the pile end the lateral volume gradually becomes zero.

Abstract: Taking working well of tunnel crossing river for example, aimed at construction problem, the software of PLAXIS3D is used to simulate excavation, strut dismantling and water injecting. Several kinds of soil-reinforcing forms are also simulated to analyses the relation between soil-reinforcing form and retaining wall deformation.

Abstract: In recent years accidents in deep excavation have frequently occurred, which brought a heavy loss in lives and property. The past cases of accident indicated water was a key one of accident resource. In this paper, water-control and its influencing factors in deep excavation were researched from sealing, draining and dewatering, and then fault tree of waterproofing was set up. The probability of waterproofing failure was calculated using Fuzzy Mathematics, and importance degrees for basic events were analyzed to find the events which would lead to the occurrence of the top event. The analysis can be used to make safety measures.

Abstract: In recent years, soil nailing wall supporting technology is widely applied in the design of pit supporting. However, in the design of deep foundation pit supporting in miscellaneous fill site, the values of cohesion and angle of internal friction, that is c and φ, are too conservative to be chosen, so the security and economy cannot be obtained together. To study the influence of c and φ values on deep foundation pit supporting design in miscellaneous fill site, Lizheng-FSPw60 was the analysis software, and the circular sliding simple slice method was the theory. It is concluded that cohesion and internal friction angle of the soil have great influence on the stability of the soil nailing wall. Analysis and practice show that if c and φ values are reasonably chosen, the slope supported by soil nailing wall in thick miscellaneous fill site will be much safer, and the project will be less wasteful.

Abstract: Group excavation engineering is a typical engineering roadblock in the process of urban underground space development . The concept of group excavation engineering was put forward and its features was described combined with practical engineerings. On the base of analysising the sections relevant group excavation engineering in Chinese codes, suggestions were given in the aspects of engineering investigation,design,construction and monitoring. At last,we point out that the theory is far behind the practice application in group excavation engineering.