1, foundation pit excavation

The excavation size of the working pit is determined according to the actual situation on site. The depth of the working pit is determined according to the pipe pulling water and the surface elevation. In order to ensure the drying and reaming construction in the working pit, a mud sedimentation tank is set on the south side of the working pit, and a mud pump is set at the bottom of the pool to extract excess mud at any time.

2, the drilling rig is placed

According to the actual situation on site. Because the soil at the pit is soft, and the pipe pulling distance is long, the tensile force is large, the bottom foot of the drilling rig should be placed on the 20cm thick C15 concrete flat foundation, and 920 steel bars (ground anchors) are reserved in the flat foundation concrete and the drilling rig is welded tightly to prevent the foundation settlement from affecting the stability of the drilling rig.

3, the configuration of drilling fluid

① The good or bad of drilling fluid plays a very critical role in the success or failure of tubing construction. Drilling fluid has cooling drill bits, lubricating drilling tools, and more importantly, it can suspend and carry drill cuttings, so that the mixed drill cuttings become flowing mud and smoothly discharge out of the hole. It not only provides enough annular space for the tug-back pipeline, but also reduces the weight and resistance of the tug-back pipeline. The mud remaining in the hole can play the role of wall protection.

② Drilling fluid is composed of water, bentonite and polymer. Water is the main component of drilling fluid, and bentonite and polymer are usually called drilling fluid additives. The better the quality of the drilling fluid and the more appropriate the mixing of drill cuttings, the better the fluidity and suspensions of the manufactured mud, the more ideal the effect of re-expanding into holes, and the greater the probability of success.

③ In order to improve the performance of the mud, sometimes an appropriate amount of chemical treatment agent should be added. Caustic soda (or soda ash) can increase, viscosity, static shear force, adjust the pH value, and the amount of caustic soda input is generally 2% of the amount of bentonite.

4, guided drilling

① After the drilling rig is in place, adjust the guide rod of the drilling rig to a position slightly higher than the center elevation of the design pipe position, and drill horizontally into the soil. A transmitter is installed in the guide drill bit. Through the ground receiver, parameters such as the depth of the drill bit, the facing angle of the duckbill plate, the top angle of the drill hole, the temperature of the drill bit and the battery condition are measured, and the measured parameters are compared with the drilling track for timely correction. The ground receiver has the function of display and transmission, which wirelessly transmits the received hole bottom information to the receiver of the drilling rig and displays it. The operator manipulates the drilling rig to drill according to the correct track according to the signal feedback. During the guide drilling process, the technician judges the deviation between the position of the guide head and the drilling route map according to the signal sent back by the detector, and adjusts it at any time. And record the adjustment value in the corresponding table of "drilling position".

② In order to ensure that the guide head can move forward in strict accordance with the instructions issued by the operator, it is necessary to encrypt and refine the control points after the preliminary layout of the pipeline line. Set the center line and elevation control points at an interval of 3 meters, make obvious signs with wooden piles, and use concrete to build piers around the pile point to protect. The control personnel operate the equipment strictly according to the point. ③ According to previous construction experience, the PE pipe is pulled in the hole by gravity during the process, and the pipe will sink. Therefore, in this project, the drilling point of the guide drilling is selected slightly higher than the designed pipe center line. In order to reduce the influence of the pipeline's own weight on the elevation.

5, reaming

① After the guide hole is drilled, remove the drill bit and the direction control system, and install the reexpander for pre-expansion. According to the construction experience, this reaming adopts gradually increasing the expansion into holes. The specifications of the reamer are φ 350, medium 450, φ 550, φ 650, φ 750. In order to make the expanded hole better, the reaming speed should not be too fast, the punching time should be greater than 3 minutes/root, the mud viscosity should be maintained between 45-50 seconds, and the amount of mud should be kept in the hole to fill with enough mud.

② The size of the reamer is 1.2 to 1.5 times the diameter of the laying pipe, that is, 30cmX1.5 = 45cm. In this way, the mud flow can be kept smooth and the pipeline can be safely and smoothly dragged into the hole. The distance for pulling back the reaming hole and laying the pipe is relatively long, and the role of mud is particularly important. The lack of mud in the hole will cause accidents such as hole collapse, making the guided drilling ineffective and laying a hidden danger for re-drilling. Considering that the formation mud is more prone to leakage, after the mud leakage, there is a lack of mud in the hole, and the friction between the drill pipe and the pipeline and the hole wall increases, resulting in an increase in tensile force. Therefore, it is necessary to maintain "slurry return" throughout the drilling process, and adjust the drilling fluid ratio in time according to the changes of geological conditions to produce different slurries.

③ In the construction, water, bentonite, polymer, etc. are added to the mixing chamber, and the drilling fluid is fully stirred to form the drilling fluid. Then the drilling fluid is transported to the bottom of the hole by the drilling fluid pump through the hollow drill pipe, and mixed with the drill cuttings in the hole to form mud flowing at the bottom of the hole. The experimenter needs to detect the ratio of each constituent material in the mud at any time and adjust it in time, and recycle it repeatedly.

6, pipeline welding

fused welding

the quality of the pipeline interface directly affects the success of the pipe construction, so it should be strictly carried out according to the following steps:

① Fused connection equipment and fused pipe fittings should be in correct communication, when connected, the voltage and time of electric heating comply with the provisions of fused connection equipment and fused pipe fittings;

② Fused connection cool down, no external force shall be applied to the mobile connector or the connector;

③ Fused socket connection pipe connection end should be cut vertically, the connection surface should be clean, and the insertion depth should be indicated, and the oxide layer on the surface should be scraped off. Before connection, the corresponding connector, so that it is on the same axis;

④ the lower end of the dry pipe connection part should be a bracket, and fixed anastomosis;

⑤ when the pipeline is connected, when the construction site conditions permit, welding can be carried out on the groove;

④ After the welding is completed, check whether the material in the observation hole is jacked up, whether there is a qualified weld for material extrusion at the weld should be in the process of welding, no risk (on) fire, premature shutdown and other phenomena, the observation hole of the fused part has material jacked out.

hot melt connection:

a, hot melt connection before and after the connection tool heating surface of the dirt-free application clean cotton cloth wipe;

b, hot melt connection heating time and heating temperature should comply with the hot melt connection tool manufacturers and pipe, pipe factory regulations;

C, hot melt connection pressure cooling down, shall not move the connector or connector shall not apply any external force;

d, before the pipe connection, the pipe is fixed on the rack, remove the milling cutter, close the fixture, the end face of the pipe for milling, when forming a continuous cutting, exit the fixture, check the pipe between the two ends (not more than 3mm). The fused connection painting should be clean and clean, and the surface skin should be scratched at the beginning;

e, hot-melt butt connection, the two pipe sections should each extend a certain free length of the fixture, proofread the connector so that it is on the coaxial line, and the wrong edge should not be greater than 10% of the wall thickness;

f, the heating plate temperature is suitable (220 ± 10C), when the indicator light is on, it is best to wait 10 minutes to use, so that the temperature of the entire heating plate is uniform.

g, the heating plate with suitable temperature is placed on the rack, closed the fixture, and set the pressure of the system. After reaching the heat absorption time, quickly open the fixture and remove the heating plate. Should avoid collision with the molten end face;

h, quickly close the fixture, and within the specified time, uniformly adjust the pressure to the working pressure and press the cool down button. After reaching the cooling down, press the once-cool down button to reduce the pressure to zero, open the fixture, and remove the welded pipe;

i, before unloading the pipe, the pressure must be reduced to zero, if the welding machine is moved, the hydraulic hose should be removed, and the joint dust-proof work should be done well;

j, qualified welds should have two flanges, and the outer circumference of the pipe with the weld bead rolled, the shape and size of the two flanges are uniform, without pores, bubbles, and cracks. The root of the gap between the two flanges is not lower than the surface of the welded pipe.

K, when the pipeline is connected, when the construction site conditions permit, welding can be carried out on the groove, the pipe mouth should be temporarily plugged and sealed, and operated in a strong wind environment to take protective measures or adjust the construction process.

7, after the weld and pipe strength inspection of the water pipe in the pulling pipe

are qualified, you can enter the pulling pipe construction. First, seal the pipe head with the "PE pipe envelope" made on site, and then connect the reexpanding head at the back end of the pipe head. After the pipe is connected to the transfer device for taking over, the pipe is returned to the working well, and the reexpanding head, transfer device, and remaining drill pipe are taken out. Plug the plugging head and conduct a water pressure test. During construction, the operator of the pulling machine should pull the pipe evenly and smoothly according to the equipment data, and must not pull it hard.

8, grouting reinforcement

After the PE pipe is pulled through, in order to avoid ground settlement, grouting reinforcement needs to be carried out.

① Before the construction of the pipe, connect two 25 steel pipes of the same length as the PE pipe at the front end of the PE pipe, and pull them into the soil together with the PE pipe and reach the end point of the pipe drawing design. After reaching the end point, lift the connection between the 25 steel pipe and the PE pipe, and add a 6m long and diameter grouting flower pipe in front of the two steel pipes.

② Move the pipe pulling machine to the receiving pit, connect it with the 25 steel pipe and pull it back. For every 6m pulled in, cancel the connection between the steel pipe and the pipe pulling machine, and replace it with a high-pressure grouting pump. Inject 1:1 cement and fly ash slurry (O.4MIpa) to replace the thixotropic mud and replenish the gap around the PE pipe. Then replace and pull again, pull and inject again, and repeat. Until all the steel pipes are pulled out, the grouting process is all over.

Wuhan PE towing pipe should pay attention to during grouting construction:

① According to the actual situation~ every 3-6 meters grouting once, according to the calculation The amount of grouting must be greater than the amount of mud, and try to keep it uninterrupted when grouting.

② When the flower steel pipe is dragged into the ground, it must be blocked with a plug to prevent the slurry from flowing out from the front end of the flower pipe.

9, safety protection system

due to the construction of the geological conditions complex, distance and other characteristics, in the construction must be set up the necessary safety measures, mainly:

① anti-shock alarm system, once the underground drill bit touches the cable and other live body, the drilling rig issued an electric shock alarm, at this time the operator must sit on the seat must not leave, so as to avoid electric shock. After the alarm is lifted, the operator can leave the rig.

② Remote control emergency shutdown device, while drilling tracking surveyor should always keep in touch with the rig operator, once an accident should be dealt with in a timely manner. At present, wireless communication is generally used, and sometimes due to the impact of the local environment at that time, this method can no longer cope with emergency emergencies. Therefore, in the construction should be followed by the drilling by the use of emergency measures to stop the drilling rig work, after the treatment is completed, the latter to lift the restrictions on the drilling rig, can start the drilling rig.

10, pipe fittings installation

AD PE pipeline crossing is completed, should be installed immediately according to the design drawings position tee, valves and other pipe fittings.

Trenchless tractor pipe construction method introduction, Wuhan PE tractor pipe construction, Hubei PE trenchless pipe construction can contact Hubei AD Building Materials Co., Ltd., we will provide a professional team

Source: Hubei AD Building Materials Co., Ltd., welcome to share! Hotline: 17399989993