A localized high hydraulic conductivity zone with high water pressure is denoted as a hazardous zone. This study focuses on the 3D coupled mechanical and hydraulic analysis of the effect of a front hazardous zone on shield tunnelling. The tunnelling process is modelled by a step-by-step excavation. And a series of three-dimensional coupled mechanical and hydraulic analysis are performed to estimate the distribution of the TSR of the ground ahead of the tunnel face. The result show that the tunnelling directly influences on the distribution of the pore water pressure and the TSR. The maximum influence range of the hazardous zone on the face stability is within 4 times the R value. And the high water pressure can induce a failure of the ground at the tunnel face by itself in conjunction with a poor ground condition.
Based on the tasks of automatic MIG welding machine, in this paper, a SCM control system of welding machine is presented and its anti-interference design is carried out. Some hardware measures are used to resist interference, including power supply anti-interference, channel anti-interference, space anti-interference, selection of components, circuit layout and hardware "watchdog". Redundant instruction, software "trap", software "watchdog" and other software anti-interference measures are also adopted. NB-500IGBT inverter welding machine is used for welding test and the results show that the above mentioned hardware and software anti-interference measures are effective to solve the interference for control system of automatic MIG welding machine.
Agitator impeller consist of turbine blades, positioning plates, central axis, flange, blocking plate and steel by welding, It is a typical welded structure. In the production process easy to produce deformation, cracks, undercut, not fusion, porosity and other defects, affecting life,and it is important for tacking and welding for turbine blades and positioning plates. In order to prevent the generation of welding defects, to meet the design requirements, The process of tacking and welding for turbine blades and positioning plates is designed in this paper.
In order to solve the problem of automobile rear axlewelding equipment with the low level of automation,the poor accuracy, the poorefficiency, a automatic girth welding machine with dual-arm for automobile axlehas been developed based on PLC. Thewelding Proeess automation is realized by PLC controlling gun movement. Theautomatic welding machine has the characteristics of high control precision,good security, fast response speed, high degree of automation, improving weldingquality and production effieiency, lowed serap rates, eonvenient operation, easymaintenance, in particular to improve the working eonditions of workers and improveproduetion effieieney has obvious praetical signifieanee.
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