Technical safety measures for the lightest tunnel

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According to the geological survey business contact list (No.: l), the 6131 machine Lane constructed by our company is 67.763m forward from the design orientation 101 in front of the D3 measuring point, 67.451m (horizontal distance, center to center) in front of the D6 measuring point, and the left side (north side) is connected with the 6133 air lane demolition chamber (demolition chamber specification: 4.4m deep and 4m wide). As of the morning shift on September 11, 6131 machine lane has been constructed to 41m before D6, and 26.451m (horizontal distance, center to center) is left to the demolition chamber. The tunnel construction from 60.451m to 74.451m in front of D6 point is within the scope of demolition chamber (attached Fig. 1). In order to ensure safe construction, this technical safety measure is specially prepared to guide production

II. Construction method and technical requirements:

1. Construction method:

(in order to achieve this goal 1) during the demolition of the chamber, the manual air pick excavation cooperation system is used for shipment. It is forbidden to drill holes, charge and shoot during the demolition of the chamber

(2) during the demolition of the chamber, the construction shall be carried out along the coal and the roof in strict accordance with the central line

2. Construction sequence: explore the location of the chamber - deal with gas from the construction to the chamber location - reinforce the roof at the chamber - pass the chamber - deal with hidden dangers at the top of the chamber - reinforce the pile bag with shotcrete - reinforce the I-steel of the upper station - reinforce the shotcrete grouting - make the floor of the floor

3. Exploratory chamber: through the demolition of the chamber, the construction starts from 60.451m before D6 point, while exploring and excavating to determine the position of the chamber. Exploration in the roadway, an exploration hole is constructed with an air coal drill on the left side, with a hole depth of 6m and 1m outside the roadway contour (attached Fig. 2). If there is no abnormality in the exploration, the advance projection distance (normal distance) of 3M borehole shall be reserved to control the footage; If the specific location of the chamber is detected, the exploration hole shall be blocked with gunite first, and then the construction shall be carried out in strict accordance with the construction requirements of the tunnel operation

exploratory hole design parameters:

4. During the demolition of the chamber, the anchor beam cable support is still used, and the side slope near the demolition chamber is not supported temporarily. The shoulder socket of the roof is first reinforced with an anchor cable and a ktm3 steel belt beam. The length of the anchor cable is 7.5m, and the spacing is 1.4m. The slope is consolidated after the head-on construction reaches the position of the chamber

5. Head on construction to the tunnel section, adopt the method of excavation and exploration, and detect the gas concentration in the tunnel in advance. If the gas concentration in the tunnel is high, exhaust the gas in the tunnel or use the air duct to guide the air, so as to reduce the gas concentration near the tunnel to less than 1.0%. After the chamber is completely exposed, back off and seal the upper part by filling coal in the pocket and stamping two single-layer pocket walls. The pocket wall is sealed by spraying mortar, and the pocket walls are sealed by spraying mortar. The outermost closed wall is embedded with 3 pieces during construction Φ 50mm conduit is convenient for later gas observation (the specific construction shall be subject to the arrangement of the communication and Prevention Department)

6. The back upper of the bag stacking is supported by 11# mining I-steel and reinforcement (63..45m before D6). Reinforcement method for the section to be reinforced, bolts are used to fix the 11 # I-steel with a length of 2.3m on the roof of the section to be reinforced, and the I-steel is arranged along the roadway trend. Each I-steel is fixed on the top plate with 4 anchor bolts and track splints. The spacing between fixed points is 1.5m, and the distance between the end of the I-steel and the fixed point is not less than 400mm. The fixed anchor rod adopts waste left-handed anchor rod, with a length of 1000mm. Then, 11 × I-steel with a length of 2.3m is used for back support of the upper, and a layer is paved between the I-steel and the upper Φ 5.5mm round processed reinforcement; The spacing of I-steel is 400mm (center to center), and the specifications of reinforcement are 900mm, 900mm, 3000mm, 900mm. The pieces are self connected, and the parts that cannot be self connected must be tied firmly with double strand 12 # iron wire. Under the I-steel, dig the leg socket foundation to continue to fix, and the depth of the leg socket shall not be less than 200mm

7. After the reinforcement of the upper part, shotcreting and grouting shall be carried out within 10m before and after the back section of the upper part. Before shotcreting, a layer of reinforcement shall be paved outside the back section of I-steel. The thickness of shotcreting shall not be less than 50mm, and the reinforcement can be covered after shotcreting. In the later stage, if there is gas from cracks, re spraying shall be carried out

8. Reinforce the floor 5m in front of and behind the tunnel section. The reinforcement method is to undercover within the range of 1.3m from the right side of the roadway to the middle line, with a depth of 200mm. After being undercover, grouting anchor bolt shall be installed on the roadway floor, the floor shall be paved, and grouting shall be carried out. The specification of grouting anchor bolt φ 22mm, the maximum load recorded is l=2.0m, and the spacing between rows is 1m. Cement single slurry is used, with the label of 425 × ordinary portland cement, so as to reduce the impact of its production on the environment. The grouting pressure is not less than 1.5MPa, and the floor is paved with concrete, with a thickness of 200mm

III. safety technical measures

(I) it effectively ensures the smooth implementation of board management for key engineering models such as aviation, aerospace, weapons, ships, nuclear energy, electronics, etc.

1. Before each commencement, the gas concentration in the head-on and return air flow must be checked. When the gas concentration in the head-on and return air flow is greater than 0.8%, the operation must be stopped and measures must be taken to deal with it. The construction can only be carried out after it is handled

2. During the demolition of the chamber, before the commencement of each shift, the shift leader must arrange special personnel to strictly implement the system of knocking on the side and asking for the top, and use the top finding tool to find the live gangue dangerous rocks on the roadway top and side within 20m around the construction site. The top finding personnel must be experienced old workers who have received practical training and passed the examination. When finding the top, they must stand in a safe place with good roof support and ensure the safety and smoothness of the back road; The top finding work should start from a safe place with good support, from the outside to the inside, first the top and then the two sides, and it is not allowed to carry out other work at the same time

3. When knocking on the top, one person must find the top and one person must observe the top. The person observing the top should stand at the side of the top finder in a safe place, keep focused, carefully observe the top condition, and immediately withdraw to a safe place if abnormal conditions are found

4. When knocking on the top of the wall, if there is a "Dong" sound when knocking on the top of the wall, immediately look for it. It should be carried out slowly along the fissure bedding, and hard planing is not allowed

(II) technical safety measures for I-shaped steel beam on the roof

1. First mark the eye position of the fixed anchor bolt according to the fixed position of the I-shaped steel beam, and hit the fixed anchor bolt of the roof. If the waste anchor bolt with a crack length of 1.0m in the roof cannot be anchored, the long anchor bolt must be selected to ensure reliable anchoring

2. The I-steel beam on the top plate is operated by three people together. Two people lift the I-steel beam, and one person fixes the I-steel beam on the top plate steel strip or anchor bolt tray with double strand 12

1. Before stacking bags, deal with the potential safety hazards of the surrounding roof, and ensure that there are no potential safety hazards before construction

2. Mining flame-retardant bags are used for stacking bags, with two-thirds of each bag filled with coal, and the bag mouth is tied tightly

3. Stack bags with staggered stubble and seam pressing. All bag buttons are used towards the old empty area. It is strictly prohibited to re sew and butt sew

(IV) safety technical measures for shotcreting

1. First check the safety situation of the shotcreting site, and use a special top finding tool no less than 1.8m long to find out the live gangue and dangerous rock in the section to be shotcreted

2. Clean up the sundries on the spraying site, connect the air and water pipelines, the material conveying pipeline should be straight without sharp bends, the joint should be tight, and the connection should be firm and reliable with special clips, without air leakage, and it is strictly prohibited to use non antistatic plastic pipes as material conveying pipes

3. Check whether the shotcreting machine is in good condition, and power on the no-load test run. Fasten the friction plate, and there shall be no air leakage

4. When spraying concrete and mortar with manual feeding sprayer, damp materials must be used

5. Before shotcreting, the place to be sprayed must be washed with water, and the concrete shall be sprayed on the local section. It is strictly forbidden to miss or not spray

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