1 Engineering and hydrogeology overview
Szechiaying iron ore located in Luan County in Hebei, convenient transportation. The main well in the mine field is 638m deep, the net diameter of the wellbore is 5.6m, and the height of the wellhead is 38m. The main well-525m measuring chamber consists of a metering room, an operation room, a belt path and a metering bucket. The excavation work includes a metering room, an operation room, a belt path, and a metering bucket.
According to the geotechnical investigation report, the compressive strength of the stratum rock in the -525m measuring chamber is about 107MPa, which is a hard rock with a crack width of 0.2~1mm, filled with calcium and flat.
From 554 to 567m, it is a diorite porphyrite, gray-green-grey black, fine-grained crystal structure, plaque structure, the main mineral composition is feldspar , hornblende, quartz , which is a hard rock, mainly from 20° to 30°. The fractures of the two groups from 40° to 50° were developed, filled with calcium, the roof inclination angle was 60°, 556.2～557.2m, 559.0～559.2m, respectively, mixed granite , and the basic quality grade of rock mass was grade III.
565.9～570.3m is a diorite porphyrite, gray-green-grey black, fine-grained crystal structure, plaque structure, main mineral composition feldspar, hornblende, quartz, belonging to hard rock, mainly from 20°~ 30°, 60°～70°, the two groups of fractures develop, filled with calcium, a small amount of muddy, 565.2～567.4m, which is mixed granite, and the basic quality grade of rock mass is grade IV.
Because the wellbore construction adopts pre-grouting on the working face, the water in the construction site is not drastic; the water in the wellbore is controlled by intercepting, blocking, guiding and discharging, which does not affect the construction.
2 digging room
2.1 Requirements for excavation of each chamber (1) Measurement room specification (width × height) 6500mm × 6567mm, length 7153mm, 200mm thick bottom, 400mm high wall foundation; 400mm thick C30 plain concrete support, support thickness 50mm, Floor concrete strength grade C10, paving thickness 200mm.
(2) Operating chamber specifications (width × height) 3500mm × 3967mm, length 4300mm, wall base height 300mm, bottom 200m thick; chamber with plain concrete support, strength grade C30, support thickness 300mm; floor concrete strength C10 .
(3) Belt specification (width × height) 4400mm × 3667mm, length 8000mm, 300mm high wall foundation, plain concrete support, concrete strength grade is C30, support thickness is 300mm; floor thickness is 200mm, concrete strength is C10.
(4) The measuring bucket size (length × width × height) 5609mm × 4500mm × 10950mm, the total excavation amount is 896.87m3. It adopts 400mm thick C30 plain concrete support, the temporary support thickness is 50mm, the permanent support thickness is 350mm, the floor concrete strength grade is C10, and the bottom is 300mm thick.
2.2 Construction scheme Considering the compressive strength of rock is about 107MPa and the inclination angle of rock is 80°, it is difficult to construct rock formation; the measuring chamber is larger, the height is higher, the engineering quantity is large, the construction is complicated, the overall construction safety and quality are not easy to guarantee. The top-down layered pouring operation is convenient and easy to control. When the wellbore is being excavated, the metering room, the operation room, the belt path, the metering bucket are drilled, and then the overall casting construction plan is carried out together with the wellbore.
2.3 Construction process
2.3.1 Tunneling
The wellbore is drilled by conventional methods of umbrella drilling. The horse head door adopts YT28 type pneumatic drill, B25 hexagonal hollow steel brazing, and 32mm bead tooth bit. After the blasting of the charge, the slag slag machine is installed by the hoisting disc, and the slag indoors is all smashed to the wellbore, and the center slewing rock grab is loaded to the ground.
2.3.2 Support and pouring (1) Temporary support. Due to the high position of the empty gang, the long pole tool after the blasting cuts off the pumice , and the spray coating is supported, and the spray layer is 100mm thick.
(2) Permanent support. TUNNELING chamber and a wellbore segment immediately after a permanent support, in use the wellbore sliding, chamber fabricated using a metal template, complementary binding wooden template installation, then pouring together, concrete strength C30.
When the concrete is poured 1m high, the template is laid upwards and continues to be poured until the large formwork is flattened, and then the template of the remaining horse head door arch is fully laid. After the concrete is solidified for 12 hours, the sliding mold is raised to 500 mm above the dome of the chamber. The remaining diverticulum arches and the wellbore are integrally poured, and the upper section of the well wall is combined, and the side is vibrated while pouring.
For the water in the well wall, the concrete is blocked by the air duct cloth or linoleum before the concrete is poured, and the water is taken out by the installation conduit; the conduit for the concentrated water outlet is directly led outside the template.
Concrete materials, proportioning, fabrication, and transportation are consistent with wellbore construction. When pouring concrete, it should be symmetrical, continuous, layered and vibrating, and the layer thickness should be within 300mm.
(3) Treatment of the joints of the well wall. The ash sluice is broken from the upper shaft wall by the wind shovel, and the joint is poured. After the pouring is completed, the iron plate is used to fill the rupture.
(4) Demoulding. The concrete can be removed after pouring concrete for 3 days. The order of demoulding should be from the outside to the inside to prevent the injured personnel. The recovered form should be cleaned up in time.
2.3.3 Precautions for construction (1) The interval between layering and pouring is not more than 3h. After more than 3h, the floating surface of the pouring surface shall be cleaned and the contact surface shall be chiseled to ensure the overall pouring effect.
(2) The top of the belt and the construction of the wall, the long-distance chute is used to pour the belt wall, and the pump is placed on the top of the belt and the measuring chamber to ensure that the air-top forming meets the construction requirements; two are embedded at the top. The grouting pipe fills the empty top position with grouting.
(3) Make a wall seat 1m upwards at the lower part of the measuring chamber and the measuring tank connecting wall, to ensure the stability of the measuring chamber wall when the construction measuring tank is completed, and prevent the wall from cracking and collapsing.
(4) After the interaction strength of the upper part reaches 70% of the design strength, the mold is applied to the lower part of the construction. After the completion of the construction, the measuring line is suspended at the bottom of the measuring tank at the level of the measuring chamber -525m according to the drawings. The bottom-up mold casting work is carried out, and the large slope interface is used for the connection with the pouring chamber wall.
2.4 Difficulties in construction and treatment methods (1) Flat top pouring is prone to empty tops. The flat top pouring has a long conveying distance, and the concrete is poorly restricted by the slumping degree, and it is easy to cause an empty roof or pouring a construction accident. Solution: Appropriately change the slump of concrete, use long chute and pump to transport concrete, strengthen the vibrating work of concrete, and separate the vibrating and vibrating under the template twice.
(2) Protection of the wall of the measuring room. The metering chamber and the metering tank wall are constructed in sections, and the wall of the metering chamber is suspended after the metering tank is boring, which easily causes the wall to crack and collapse. Solution: Add a wall seat at the connection wall between the metering chamber and the metering tank to increase the strength of the wall support.
(3) The connection between the metering tank and the wall of the metering chamber. The measuring tank wall and the measuring chamber wall are of integral structure. The rock layer and safety factors are considered in the construction. It is not recommended to form one time. The upper and lower molding process is adopted, and the long slope surface is connected at the wall joint, and the contact is made. The surface is subjected to infiltration and chiseling to avoid problems with the strength of the wall joint and the strength of the wall support.
3 Conclusion
1 large-section chamber construction, layered pouring is conducive to construction operations; 2 problems in the construction of joints, air-top control, etc., special measures need to be taken to ensure the construction quality; 3 when the construction of the bucket, the method of increasing the wall seat It is stable and economical to protect the wall of the metering chamber.
Article source: "Modern Mining"; 2016.9;Author: Zhao Zhenjiang, Wu Yongqiang, Pombo; Luan County in Hebei Iron and Steel Group Co., Ltd. Chang Yu Iron;
Copyright:
Ram Packer,Ordinary Ram Packer,Assembly Ram Packer,Shearing Ram Side Seal
Sichuan Xinwei Rubber Co., Ltd , https://www.boprubber.com