For the continuous box beam bridge with variable cross section,it is not advisable to use an uniform eccentric load coefficient for the whole bridge because the shape of the influential range of live load internal force is complicated and the influences of the geometric structure of the box beam on the restrained torsional normal stress along bridge spans are variable.

The major reason behind the crack is unsynchronized placement of the derrick on each side and the high load deviation coefficient during construction.

Thus in common receiving gathers,firstly calculate the polarization coefficient of direct wave for each trace,and then use the resulted coefficients as weights to determine the main polarization direction in detector coordinates via weighted least square metho.

With a drop in formation pressure, the parameters which closely related to the flow coefficient of the exponential deliverability equation are varied, such as gas deviation factor, gas viscosity, reservoir permeability, effective thickness and so on.

On the basis of analysis of the raw materials,using the fineness modulus of aggregate mixture,the deviation factor of synthetic gradation and objective gradation as technical indexes,the best aggregate ratio is attained through the application of computer operations.