A method for laying hollow pipes by horizontal drilling and traction for landslide dam disposal

Abstract

The present invention discloses a method for horizontal drilling, traction and laying of hollow pipes for disposal of landslide dams. The drilling and laying pipe device includes a head non-excavation directional drill bit, a rear connection reamer and control equipment, and a hollow pipe traction connector. After a landslide blocking a river and a landslide lake disaster occurs, the device is used to quickly drill horizontally in a loose accumulation body and simultaneously traction and bury the hollow pipe. When the water level rises to the elevation of the pipe mouth, the control valve at the end of the hollow pipe is opened and closed cyclically, and the landslide dam is caused to slide back to the source step by step through penetration damage, and finally the landslide dam body is automatically dismantled. Compared with the existing emergency treatment technology for landslide dam disasters, the method of the present invention has rapid construction, simple operation, and resource conservation. It can respond quickly when a landslide blocking a river disaster occurs, and while controlling the risk of dam collapse, it can gradually dismantle the landslide dam with the help of the natural force of water to ensure the safety of the upstream and downstream of the valley.

Description

Technical Field

[0001] The invention belongs to the technical field of water conservancy projects, and in particular relates to a method for horizontally drilling, pulling and laying hollow pipes for landslide dam disposal. Background Art

[0002] A barrier lake is a temporary body of water formed in the flow path of streams, rivers, lakes, or other bodies of water due to geological disasters (such as landslides, debris flows, and rockfalls) or natural disasters (such as earthquakes and floods). Landslide-dammed rivers often occur in steep mountainous areas or canyon regions. When the water level of a barrier lake reaches a certain height, it will exert tremendous pressure on the barrier dam. If the barrier dam is unable to bear the pressure and overflows, its loose accumulation will cause the speed and intensity of its failure to far exceed that of a compacted earth-rock dam of the same size. The released floodwaters and debris flows will collapse or inundate downstream towns, villages, roads, bridges, and other structures, causing massive casualties and property losses exceeding those of a similarly large dam failure. Therefore, a barrier dam disaster is an extremely serious natural disaster.

[0003] Current research on landslide dam disaster management mainly includes blasting, mechanical dredging, artificial drainage, grouting reinforcement, development and utilization, etc. Among them, the methods for dismantling landslide dams generally include blasting and direct water release from the top of the dam. The disadvantages of blasting are: first, blasting to dismantle landslide dams is very unstable. Under the high head pressure upstream, the use of blasting is likely to directly cause a large-scale dam collapse, endangering the lives and property of people downstream; second, blasting is greatly restricted by the specific conditions of the landslide lake on site and requires comprehensive consideration of geological and hydrological factors. In many cases, blasting measures cannot be taken and the only option is to seek less efficient dredging and drainage methods. The disadvantages of top excavation and water release are: slow construction speed and low dredging efficiency. It is difficult to control the amount of water released and is prone to dam collapse risks. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a method for horizontally drilling and hauling hollow pipes for landslide dam disposal. Unlike traditional horizontal directional drilling (HDD) pipeline crossing techniques, this method integrates drilling, expansion, and hauling processes. The pipeline to be crossed is a hollow steel pipe, eliminating the risk of collapse. The minimum pipe diameter is 1600mm, and personnel can follow the tunnel face to directly control or resolve any problems. Lubrication of the hollow pipe walls along the way reduces drag, ensuring that the equipment power meets the frictional resistance of the pipe of a specific diameter and length.

[0005] The technical solution adopted by the present invention to achieve the purpose of the invention is: a method for horizontal drilling and traction laying of hollow pipes for landslide dam treatment, including a device for horizontal drilling and traction laying of hollow pipes for landslide dam treatment, the device including a non-excavation directional drill bit at the head, a reamer at the back, a drill bit control device arranged at the tail of the reamer, and the drill bit control device is connected to the hollow pipe to be laid through a detachable connector.

[0006] Trenchless horizontal directional drilling and traction pipe laying are completed in one step, including the following steps:

[0007] Step 1: After a landslide blocking a river and creating a barrier lake disaster occurs, the rising speed of the barrier lake water level is predicted using the river flow data, and the construction schedule of the method of the present invention is matched to determine the elevation 1 of the upstream end of the pipeline above the water surface when the laying is completed.

[0008] Step 2: Determine the design guide trajectory for drilling excavation traction based on elevation 1, and arrange a working platform at elevation 1 upstream of the landslide dam; select the construction direction from downstream to upstream or from upstream to downstream based on the actual situation on site.

[0009] Step 3: According to the designed guide trajectory, use the aforementioned device to complete the trenchless drilling and traction laying of the hollow pipe in one go.

[0010] During the drilling and traction process, polymer bentonite lubricating drag-reducing slurry is injected through the holes in the hollow pipe body to the sand and gravel hole walls around the pipe, thereby lubricating the outer periphery of the drag-reducing pipe and protecting the wall.

[0011] For a dam with an upstream and downstream length exceeding 700m, the peripheral friction resistance of the pipeline exceeds the maximum push-pull force of the drilling rig. When implementing this method, a hydraulic pipe-pushing machine can be added to the outside of the dam to meet the dragging and traction force of the hollow pipeline.

[0012] Step 4: After drilling and laying are completed, remove the connector and install the control valve at the downstream end of the hollow pipe.

[0013] Step 5: Transport the trenchless directional drill, reamer, and drill control equipment to the construction starting point, set up a new elevation 1 work platform, and repeat steps 3 to 4 to lay other hollow pipes.

[0014] Step 6: The terminal control valve is closed. After the reservoir water level rises and submerges the upstream pipe opening of the hollow pipe, water enters the pipe and is pressurized. Water then flows out of the holes in the hollow pipe body, causing seepage damage to the loose accumulation of the landslide dam, and even erosion and scouring, gradually tracing back to the source from the end and causing collapse and loss. When the reservoir water level rises to the risk threshold elevation, the control valve is opened to lower the reservoir water level to control the risk of overtopping and dam breaching, and then the next round of seepage damage cycle is carried out. While controlling the risk of dam breaching, the landslide dam is gradually dismantled with the help of the natural force of water seepage damage.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The hollow pipe is directly pulled by the trenchless horizontal directional drilling device, and the pipe is laid while drilling. This achieves high-speed and high-efficiency treatment of landslide dam disasters and solves the problem of long time spent on landslide dam disaster treatment.

[0017] (2) By drilling holes and laying hollow pipes inside the loose accumulation after the landslide dam disaster to induce seepage damage to the landslide dam, the low-risk automatic demolition of the landslide dam was achieved, solving the problems of difficult, high-risk and high-cost management of landslide dam disasters. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a cross-sectional view of the structural arrangement of the present invention.

[0019] Figure 2 It is a device elevation view of the present invention.

[0020] Figure 3 It is an elevation view of a pipe-pushing hydraulic press of the present invention.

[0021] 1 - Trenchless directional drill bit; 2 - Hole expander; 3 - Drill bit control equipment; 4 - Removable connector; 5 - Weir; 6 - Working platform; 7 - Designed guide track; 8 - Hollow pipe; 9 - Pipe pushing hydraulic press; 10 - Control valve; 11 - Pipe body hole. DETAILED DESCRIPTION

[0022] The present invention designs a method for horizontal drilling and traction laying of hollow pipes for landslide dam disposal. Its structure consists of a trenchless directional drill bit 1 at the head, a reamer 2 at the back, a drill bit control device 3 arranged at the tail of the reamer 2, and the drill bit control device 3 is connected to the hollow pipe 8 to be laid through a detachable connector 4. Trenchless horizontal directional drilling and traction pipe laying can be completed in one step during the construction process.

[0023] To successfully implement the method provided by this invention, it is crucial to accurately estimate the push and pull forces required to pull the pipeline and select the appropriate drilling rig accordingly. The method proposed in this invention recommends using Equation 5.4.2 from the "CECS 382-2014 Technical Specification for Pipeline Crossing Engineering Using Horizontal Directional Drilling" to estimate the required push and pull forces:

[0024]

[0025] Where:

[0026] L——Pipeline length (m)

[0027] T——the traction force on the pipeline (kN);

[0028] fh - the friction coefficient between the through-steel pipe section and the drilled hole wall, generally taken as 0.1~0.3;

[0029] γm——density of drilling mud (kN / m3);

[0030] γm——weight of pipe (kN / m2), steel pipe is 78 kN / m2;

[0031] K is the viscosity coefficient of the lubricant (kN / m2), which is 0.15~0.35. The larger the value, the higher the viscosity of the lubricant, and the smaller the value.

[0032] D1——outer diameter of the pipe (m);

[0033] D——inner diameter of the pipe (m);

[0034] t——pipe wall thickness (m).

[0035] Consider a trenchless directional drilling rig that can provide 9000kN push and pull force, the friction coefficient between the pipe and the hole wall is 0.1, and the drilling mud density is 2t / m3. According to the above formula, it can be estimated that it can pull a steel pipe with an outer diameter of 1.9m, an inner diameter of 1.8m, and a length of 617m; or pull a steel pipe with an outer diameter of 1.6m, an inner diameter of 1.5m, and a length of 732m; for small and medium-sized landslide dams with a length of less than 700m along the river, the present invention has sufficient feasibility; for landslide dams with a length of more than 700m along the river, it is necessary to consider installing a pipe-pushing hydraulic press at the tail.

[0036] The maximum operating speed of the drill bit of the trenchless directional drilling rigs on the market is generally 20~30m / min. In the loose accumulation of the landslide dam, its travel speed is 2m / min, and the drilling length in 24 hours can reach 2880m. This highly efficient construction method can respond quickly after the landslide blocking the river disaster, quickly lay the hollow pipe, and effectively avoid the occurrence of dam failure disasters.

[0037] During the process of drilling and laying hollow pipes, engineering personnel can be arranged to enter the hollow pipes according to actual conditions and spray bentonite lubricant into the hole walls through the holes in the pipe body to lubricate and reduce resistance; or before laying the pipes, a layer of bentonite lubricant can be brushed on the hollow pipes in advance to reduce resistance; a variety of polymers can also be added to bentonite to improve its performance, thereby achieving the purpose of lubrication, drag reduction and wall protection.

[0038] This method specifically includes the following devices and steps:

[0039] The device includes a trenchless directional drill bit 1 at the front, a reamer 2 at the rear, a drill bit control device 3 at the rear of the reamer 2, and the drill bit control device 3 is connected to the hollow pipe 8 to be laid through a detachable connector 4.

[0040] Step 1: After a landslide blocking a river and creating a barrier lake disaster occurs, the rising speed of the barrier lake water level is predicted using the river flow data, and the construction schedule of the method of the present invention is matched to determine the elevation 1 of the upstream end of the pipeline above the water surface when the laying is completed.

[0041] Step 2: Determine the design guide track 7 for drilling excavation traction based on elevation 1, and arrange a working platform 6 at elevation 1 upstream of the landslide dam 5; select the construction direction from downstream to upstream or from upstream to downstream based on the actual situation on site.

[0042] Step 3: According to the designed guide track 7, the aforementioned device is used to complete the trenchless drilling and traction laying of the hollow pipe 8 at one time.

[0043] During the drilling and traction process, polymer bentonite lubricating drag reducing slurry is injected into the sand and gravel hole wall around the pipe through the hole 11 of the hollow pipe body to lubricate the periphery of the drag reducing pipe and play a role in protecting the wall.

[0044] For a dam with an upstream and downstream length exceeding 700m, the peripheral friction resistance of the pipeline exceeds the maximum push-pull force of the drilling equipment. When implementing this method, a pipe-pushing hydraulic press 9 can be added outside the dam to meet the dragging and traction force of the hollow pipeline 8.

[0045] Step 4: After drilling and laying are completed, remove the connector 4 and install the control valve 10 at the downstream end of the hollow pipe.

[0046] Step 5: Transport the trenchless directional drill bit 1, the reamer 2 and the drill bit control device 3 to the construction starting point, set up a new work platform at elevation 1, repeat steps 3 to 4, and lay other hollow pipes 8.

[0047] Step 6: The terminal control valve 10 is closed. After the reservoir water level rises and submerges the upstream pipe mouth of the hollow pipe 8, water enters the pipe and is pressurized, and water flows out of the pipe body holes 11 of the hollow pipe 8, causing seepage damage to the loose accumulation of the landslide dam, and even erosion and scouring, gradually tracing back to the source from the end and causing collapse and loss; when the reservoir water level rises to the risk threshold elevation, the control valve 10 is opened to lower the reservoir water level to control the risk of overtopping and dam breaching, and then the next round of seepage damage cycle is carried out; while controlling the risk of dam breaching, the landslide dam is gradually dismantled with the help of the natural force of water seepage damage.

Claims

1. A method for laying hollow pipes by horizontal drilling and traction for landslide dam treatment, comprising a device for laying hollow pipes by horizontal drilling and traction for landslide dam treatment, the device comprising a trenchless directional drill bit (1) at the head, a reamer (2) at the rear, a drill bit control device (3) arranged at the rear of the reamer (2), the drill bit control device (3) being connected to the hollow pipe (8) to be laid via a detachable connector (4); characterized in that: Trenchless horizontal directional drilling and traction pipe laying are completed in one step, including the following steps: Step 1: After a landslide-dammed lake disaster occurs, use the river flow data to predict the rate of water level rise in the lake, match the construction schedule, and determine the elevation of the upstream end of the pipeline above the water surface when the pipeline is completed; Step 2: Determine the design guide track (7) for drilling excavation traction based on the elevation, and arrange a working platform (6) at the elevation position upstream of the landslide dam (5); select the construction direction from downstream to upstream or from upstream to downstream according to the actual situation on site; Step 3: According to the designed guide track (7), the aforementioned device is used to complete the trenchless drilling and traction laying of the hollow pipe (8) at one time; Step 4: After drilling and laying are completed, remove the connector (4) and install the control valve (10) at the downstream end of the hollow pipe; Step 5: transport the trenchless directional drill bit (1), the reamer (2) and the drill bit control device (3) to the construction starting point, set up a new elevated working platform, repeat steps 3 to 4, and lay other hollow pipes (8).

2. The method according to claim 1, wherein: In step three, during the drilling and traction process, polymer bentonite lubricating drag reducing slurry is injected into the sand and gravel hole wall around the pipe through the pipe body hole (11) of the hollow pipe to lubricate the outer periphery of the drag reducing pipe and play a wall protection role.

3. The method according to claim 1, wherein: In step three, for a dam with an upstream and downstream length exceeding 700m, the peripheral friction resistance of the pipeline exceeds the maximum push-pull force of the drilling equipment, and a pipe-pushing hydraulic press (9) is added outside the dam to meet the dragging and traction force of the hollow pipeline (8).

4. The method according to claim 1, wherein: The terminal control valve (10) is closed, and after the reservoir water level rises and submerges the upstream pipe opening of the hollow pipe (8), water enters the pipe and is pressurized, and water flows out of the pipe body holes (11) of the hollow pipe (8), causing seepage damage to the loose accumulation of the landslide dam, and even erosion and scouring, gradually tracing back to the source and sliding from the end; when the reservoir water level rises to the risk threshold elevation, the control valve (10) is opened to lower the reservoir water level to control the risk of overtopping and dam breaching, and then the next round of seepage damage cycle is carried out; while controlling the risk of dam breaching, the landslide dam is gradually dismantled with the help of the natural force of water seepage damage.

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