ترجمه مقاله نقش ضروری ارتباطات 6G با چشم انداز صنعت 4.0
- مبلغ: ۸۶,۰۰۰ تومان
ترجمه مقاله پایداری توسعه شهری، تعدیل ساختار صنعتی و کارایی کاربری زمین
- مبلغ: ۹۱,۰۰۰ تومان
Abstract
Physical modeling has played an important role in studies related to excavation of tunnels in soft ground. A variety of modeling techniques have been developed by researchers all over the world to study ground response to tunneling. These techniques range from the two-dimensional trap door tests to the miniature tunnel boring machines that simulate the process of tunnel excavation and lining installation in a centrifuge. This paper presents a review of selected physical models that have been developed and used in soft ground tunneling research. Furthermore, this paper discusses some of the various approaches used to record soil deformation and failure mechanisms induced by tunneling. Experimental setups and sample results are presented for each technique as described by original authors. A summary of the advantages and disadvantages of each method is also presented.
5. Summary and conclusions
Physical modeling of soft ground tunnels is an essential part of the analysis and design of tunnels. Physical models can provide data that can validate and calibrate numerical models. For several decades, numerous researchers around the world have developed and implemented a variety of techniques to simulate the tunnel excavation process. Reduced scale tests under 1g conditions provide full control over the excavation method. However, they do not accurately simulate the in situ stress conditions. Centrifuge testing makes a more realistic simulation of in situ stresses possible but the tunnel construction process has to be simplified. Different methods have been developed to simulate the process of tunnel construction in soft ground. Soil arching around excavated tunnels has been successfully simulated using the trap door method. Vertical stresses as well as surface displacements can be investigated by lowering a trap door under 2D or 3D conditions. Stability of the tunnel face can be investigated using a rigid tube with flexible membrane at the face. Tunnel excavation is simulated, in this case, by reducing the air pressure inside the tunnel and monitoring the soil movements. Other methods include the dissolvable polystyrene core showed some success; however, the tunneling induced surface settlement was not uniform. In addition test results were less satisfactory when the excavation was made under water. Techniques based on hand or mechanical augering to represent tunnel excavation and progressive face advance seem more realis- tic, however, mechanizing the test in the centrifuge is very expensive. Further experimental research is, therefore, needed to enhance the existing techniques and to develop new methods that allow one to simulate actual tunnel construction. Table 1 summarizes the advantages and disadvantages of the modeling techniques discussed above.