Research On The Key Techniques In Civil Engineering For Relocation And Rebuilding Projects Of Northeastern Old Industrial Bases

Based on relocation and retrofit project of northeastern old industry bases, the paper studies the engineering difficulties and the key techniques encountered in this process. After vast investigation for old factory and new factory of Shenyang Locomotive&Rolling Stock Co. Ltd., understood the present engineering difficulties and the key techniques waiting to be solved, which includes the design theory and method for the foundations of large scale dynamic machines, the propagation and attenuation regulation of industrial vibration, the treating techniques for defective subgrade and earthquake response for engineering field.With the rapid development of the industrial technology, machines and equipments in factories are accordingly updated and renewed. It is common that large weight, high speed and super power dynamic machines are in general use in daily industrial production. Because of two different theoretical models adopted by the domestic code and foreign code, it is technical lagging and conceptual misunderstanding to use present code to design the foundations for the dynamic machines, especially for the imported ones.Based on the facts presented, the paper initiated from practical project, discussed two analytic models for dynamic foundation-ground system, extracted and combined merits of each model, further obtained a frequency dependent parameter model with computational convince and higher accuracy. Advanced a synthesis design method with combination of this new model and present design code. This method recommends that, for a more precise design of machine foundations, it is necessary to take the present code as a prototype, take full advantages of its brevity, utility, generality and abundance in empirical parameters, use frequency dependent parameters as a revision and complement. With a real example, verified the effectiveness and accuracy of this design method.Considered the industrial vibrations widely exist in factories coupled with the roughness and singleness of present code, which only defines one dimension component vibration. In fact, however, the surface wave has three dimensions no matter which types of vibration origins. The paper carried out vibration test for the continuous excitation and instant impulse, revealed propagation and attenuation regularities of3D surface waves of different origins, distances, frequencies and components. Pointed out that the present code is accurate in computing the surface wave of far field, while underestimates the surface wave of near field. Meanwhile, f the paper suggests some revised factors or revision and complement of the code. This can supply sound suggestions for scientific planning of factory zone and rational distribution of equipments.For the defective subgrade in new factory field, the paper advanced’double shear damage’model for CFG composite subgrade technique based on the analysis of equal sedimentation plane. Deduced the methods for computation of thichness of cushion, axial stress in neutral point, bearing capacities of up and down parts for CFG composite subgrade. These compose the new method in computing the bearing capacity of CFG composite subgrade, the paper further verified the reliability and the precision of the method. This will prompt to complete the computation theory and relative damage mechanism of CFG composite subgrade.Meanwhile, the paper illustrates some common computation methods for sedimentation—analytic, numerical and empirical method, discussed and compared all these methods. Based on deformation model of the subgrade sedimentation, considering pile length, pile diameter, subtitute ratio, position of equal sedimentation plane, friction factors and deformation modulus in synthesis, the paper improved the computation formulas for CFG composite subgrade sedimentation and soil stress ratio.In the end of this paper, adopted equivalent linearization method to analyze the earthquake response of new factoy field, which has relatively uniform soil layers, considering overpass probabilities of63%,10%and3%individually in100years. Obtained the maximum strain of soil layers happens at depth of12.15m, reaches0.027%,0.063%and0.127%correspondingly, and the maximum accerlarations of free surface are up to0.138g,0.265g and0.316g with amplify factors2.05,2.29and2.59. The analysis also obtained that the natural frequency of1st order is between1.5-2.8Hz, and2nd order is between7-8.4Hz for the soil layers in new factory field. All these computation results provide important foundational parameters for seismic resistance design of industrial structures in new factory.Although the work based on the relocation and retrofit project of Shenyang Locomotive&Rolling Stock Co.Ltd, the same civil problems encoutered in the most large and medium industry factories in northeastern old industry bases. The research fruits are not only project oriented, but also with general application, and can provide valuable reference for the relocation and retrofit projects of all industry factories in northeastern old industry bases.