In the shield tunnel repair method of screw conveyor broken shaft

In the shield tunnel repair method of screw conveyor broken shaft - 2020 06 - 24 colleagues Cao Jinhui ( China railway group in seven innings west rail project company) Screw conveyor is earth pressure balance shield machine row soil and establish the main equipment, earth pressure balance shield installed on the machine at the bottom of the precursor and segment spell between installed, including line rise Angle from the front to rear. Screw conveyor, into precursor soil storehouse of the screw shaft and the helical blade in rotation driven by hydraulic motor, waste residue in the soil bin screw shaft, spiral blade under the joint action of unearthed along the screw conveyor casing delivery, up to the mouth. 1. Fault condition 1 earth pressure balance shield machine in shield tunnel construction, the screw conveyor in the spiral shaft speed fast, high torque, soil pressure fault, shield cutterhead torque increases at the same time, earth fault mouth not unearthed. We immediately to troubleshoot this problem, when trying to screw conveyor front viewport, found that the front of the screw conveyor screw shaft fracture, fracture position distance about 1 screw axis front end. 2m。 The earth pressure balance shield screw conveyor is shown in figure 1. 2. The structure and function, 1) Structure of the screw conveyor for the center shaft screw type structure, the cylinder casing, center shaft screw axis and spiral blade of 3 parts, suitable for conveying sand, has a good ability to resist the soil pressure, the earth pressure balance shield machine mostly adopts the screw conveyor. ( 2) The screw conveyor has the following three functions: one is the cutting knife plate under the waste residue of escape from the pressure seal soil bin; Second is formed in the process of screw conveyor in conveying residue in soil, the soil pressure along the screw conveyor attenuation within the warehouse, to maintain the stability of the pressure in the soil bin; 3 it is through adjusting screw conveyor speed change displacement quantity, adjust the pressure value of waste residue in soil storehouse, make integral pressure within the soil bin keep dynamic balance with the excavating surface earth pressure. 3. Repair methods ( 1) Before the repair to the front of the screw conveyor hydraulic and electrical line disconnect and fixed firmly to warehouse after the door closed, and clearing the maintenance operation space; The screw axis chassis left and right sides of the fracture open one size is 400 mm & times; 400 mm temporary assignment window; Clean up the dirt inside the casing, until the cleanup to screw axis breakup. ( 2) Initially positioning screw axis will go out, so to reveal the fracture site, with temporary fixed plates will be 2 broken screw axis point welding connection, back to temporary assignment window position, for welding. Slowly turn the screw axis, turn to the rupture surface convenient stop after welding position; Steel plate mat, is used to adjust the clearance between the casing diameter and spiral blade, the screw axis in the center of the casing diameter, spot welding steel pad positioning. Remove screw axis split in the temporary fixed plate separation broken axis, and through the screw axis rotation and scaling, make 2 section of the broken shaft fracture. Anastomosis after 2 section of the broken shaft alignment adjustment, in order to meet the technical requirements. Use the steel bar in the screw axis mark 3 way split, with side length on the broken shaft for a 50 mm square steel welding 3 skeleton, the length of the square steel beyond the spiral shaft fracture can be 100 mm. Preliminary positioning screw axis method is shown in figure 2. ( 3) Processing to separate 2 section of the broken shaft fracture position, the wear-resisting layer of the fault location and the weld position, clean up the spiral vane welding groove and make welding groove in spiral shaft fracture location ( The bevel Angle is 30 & deg; And a depth of 80 mm) 。 ( 4) Final positioning according to the breakup of the screw shaft 3 markers to reposition, and test again 2 broken shaft alignment, if do not conform to the technical requirements should be adjusted, ensure that after the positioning screw blade and casing diameter up, down, left and right gap. ( 5) Butt welding use cutting torch to preheat to 200 welding parts & deg; C around; Models for ER50 - used by two welder 6 wire, temporary working on both sides of casing window symmetry welding at the same time, in order to prevent the screw axis produce thermal stress deformation; Natural cooling after welding. ( 6) Commissioning check the screw axis alignment after welding, remove the screw axis positioning plate and gasket, after commissioning. Ma chine screw conveyor to slow forward rotation, and then gradually speed up to maximum speed, screw conveyor working condition. According to the above steps check screw conveyor reverse, check screw conveyor scale and work at the front gate. Ma chine controlled factory test standard. Screw conveyor inspection items and the factory standard values as shown in table. ( 7) Other work after commissioning and correct, to deal with all welds: in weld on both sides of the welding of spiral vane 3 article 30 mm steel plate, to improve the strength of the spiral blade; Welding of 3 on a screw axis positioning frame, to strengthen the strength of screw shaft fractures; Closed two temporary assignment window on the chassis, and restore the observation mouth cover plate. Complete screw conveyor screw shaft fracture site repair work. Screw axis after repair, try the earth pressure balance shield machine construction failure disappears, then put the shield construction. This article from the journal of engineering machinery and maintenance for the first issue in 2016