A construction method for crossing a river when the head of a pipe jacking machine is blocked

Abstract

The present invention relates to a construction method when a pipe jacking machine head is blocked when crossing a river, and belongs to the technical field of pipeline construction. The construction method includes the following steps: S1, measuring the blocked position of the original pipe jacking machine head and the water depth at the blocked position, and setting a cofferdam in the upper river channel; S2, after the cofferdam is formed, grouting and water-stopping are performed above and around the cofferdam to the receiving well, and the water in the working well is pumped out to confirm the water-stopping effect; S3, a circular hole smaller than the diameter of the original pipe jacking machine head is cut on the inner end face of the blocked original pipe jacking machine head, and the outer wall of the original pipe jacking machine head is retained as a pipeline; S4, a new pipe jacking machine head with a smaller diameter than the original pipe jacking machine head is selected, and a new prefabricated pipe is pushed from the working well. The new pipe jacking machine head passes through the circular hole cut in S3 to the receiving well. Grouting and water-stopping are performed through the upper cofferdam, and the outer wall of the blocked original pipe jacking machine head is used as a pipeline, thereby avoiding the construction work of excavation and extraction, shortening the construction period, and increasing safety.

Description

Technical Field

[0001] The invention belongs to the technical field of pipeline construction, and particularly relates to a construction method when a river crossing pipe jacking machine head is blocked. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Underground pipeline construction can be accomplished using both open-cut and covert methods. Pipe jacking, a covert method considered a trenchless pipeline construction method, requires minimal site changes and creates minimal disturbance. Pipe jacking involves using jacks to push prefabricated pipe sections into the ground, one at a time. Simultaneously, the jacking tool head digs the soil ahead, excavating and transporting debris within the pipe. During pipe jacking in urban pipeline construction, complex underground environments often hinder pipe jacking.

[0004] At present, the technology for handling blocked pipe heads and laying the remaining pipelines is still at the traditional processing technology level, using excavation and extraction technology. The excavation and extraction methods include: after determining the location of the blocked head, excavating from the ground until the head is blocked, and finally extracting the head. This process requires additional work such as foundation pit excavation, foundation pit enclosure, and working well construction. The treatment period is long and there are many safety hazards. If the construction route of the pipe jacking head passes through the riverbed, and the pipe jacking head is blocked within the river during construction, if the water head height at the bottom of the river is high, water seepage may even occur at the head. At this time, direct excavation and extraction are impossible. Rash excavation will greatly increase the construction cost. At the same time, due to the high water head height, the construction risk will be greatly increased. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a construction method when the head of a pipe jacking machine is blocked when crossing a river, which solves the technical problem that the pipe jacking machine head is blocked within the river and cannot continue to advance, thereby reducing construction costs.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] A construction method for crossing a river when a pipe jacking machine head is blocked comprises the following steps:

[0008] S1. Measure the obstruction position of the original pipe jacking machine head and the water depth at the obstruction position, and set up a cofferdam in the river channel above the obstruction position;

[0009] S2. After the cofferdam is formed, grouting is carried out from the cofferdam to the top and around the receiving well to stop water, and the water in the working well is pumped out to confirm the water-stopping effect;

[0010] S3. Cut a circular hole smaller than the diameter of the original jacking head on the inner end face of the blocked original jacking head, and retain the outer wall of the original jacking head as a pipe;

[0011] S4: Select a new jacking head with a smaller diameter than the original one, fix the new prefabricated pipe on the new jacking head, and then push the new prefabricated pipe from the working well. The new jacking head passes through the circular hole cut in S3 and continues construction forward until it reaches the receiving well.

[0012] S5. Remove the cofferdam and restore the river channel.

[0013] Optionally, in S1, the existing riverbed surface is measured to determine the location range of the cofferdam, which covers the obstructed position of the original jacking pipe head below; at the same time, the riverbed surface elevation at the designed cofferdam position is measured to determine the cofferdam height so that the cofferdam is higher than the river water surface.

[0014] Optionally, in S2, the position, depth, range and grouting pressure of the grouting holes are determined according to the water head at the obstructed position, grouting holes are drilled downward from the cofferdam, and grouting is performed through the grouting holes.

[0015] Optionally, in S2, the grouting range includes: from the cofferdam to the receiving well.

[0016] Optionally, in S2, cement-water glass mixed slurry is used as the grouting material.

[0017] Optionally, in S3, use a small drill to drill holes evenly on the machine head before cutting to check the water-stopping effect.

[0018] Optionally, in S3, the lower end of the cut circular hole is inscribed inwardly with the cylindrical outer wall of the original jacking pipe head, and the outer diameter of the new prefabricated pipe is slightly smaller than the inner diameter of the circular hole.

[0019] Optionally, in S4, a new prefabricated pipe is fixedly welded to the rear of the new pipe jacking head by means of a boot, and the new pipe jacking head and the new prefabricated pipe are jacked in by means of a hydraulic jack.

[0020] Optionally, in S4, the new prefabricated pipe is a steel prefabricated pipe, which is connected and fixed to the new jacking head by welding, and multiple sections of the steel prefabricated pipe are fixedly connected by welding.

[0021] Optionally, in S4, the axis of the new jacking machine head coincides with the center of the circular hole cut in S3; during the jacking process, the new jacking machine head is corrected at all times to ensure that the axis of the new jacking machine head and the circular hole in the old machine head are on the same horizontal line.

[0022] Optionally, in S4, a flow rate sensor is added to the spiral excavator of the new jacking machine head to monitor the flow rate in the screw conveyor in real time to warn of eruption accidents; a soil pressure sensor is set in the new jacking machine head, and a jacking force sensor is set at the jack. During the jacking process, the soil pressure value in the soil bin and the change value of the jack force are monitored at all times to meet the soil pressure balance condition and maintain the stability of the excavation surface.

[0023] The beneficial effects of the present invention are:

[0024] 1. The construction method proposed in this invention can cost-effectively handle the situation where a pipe jacking machine head is blocked during river crossing. By grouting the cofferdam above to stop water, and using the outer wall of the blocked pipe jacking machine head as a pipeline, there is no need to build a new working well above the obstruction to lift the blocked machine head out, thus avoiding the construction work of excavation and extraction, shortening the construction period and improving safety.

[0025] 2. The present invention uses a new pipe jacking head to continue construction along the original construction route, eliminating the need to change the construction route. Furthermore, the lower end of the cut circular hole is inscribed inwardly with the cylindrical outer wall of the original pipe jacking head, allowing the newly pushed prefabricated pipe to contact the original prefabricated pipe, preventing the new prefabricated pipe from hanging inside the original prefabricated pipe and ensuring the reliability and durability of the new pipe section. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 Schematic diagram of the construction method in Example 1.

[0028] Figure 2 This is a schematic diagram of the positions of the new and old pipelines in Example 1.

[0029] Figure 3 Schematic diagram of the connection relationship between the new steel prefabricated pipe segment and the new pipe jacking head in Example 1.

[0030] Among them: 1. Working well; 2. Receiving well; 3. Original pipe section; 4. River; 5. Obstructed location; 6. Cofferdam; 7. Grouting hole; 8. Circular hole; 9. Cylindrical outer wall; 10. New steel prefabricated pipe section; 11. New jacking machine head; 12. Overshoe; 13. Formation. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0033] Example 1

[0034] like Figure 1 As shown in the figure, when using the pipe jacking method for underground pipeline construction, a working well 1 and a receiving well 2 leading to the underground construction location are established at the starting and ending points of the construction route. At the beginning of construction, the original pipe jacking head is hoisted into the underground construction position at working well 1, and the original pipe section 3 is gradually pushed in using jacks. When the pipe jacking head reaches below river 4, on-site personnel find that the pipe jacking head is not advancing. Initially, they believe that the pipe jacking head is damaged or has hit a hard obstacle. Twenty minutes later, water begins to seep from the opening of pipe jacking working well 1.

[0035] The debris removed from the mud on site was identified as concrete blocks, rebar heads, and sheet metal fragments. In this case, the tunnel boring machine head was used for soil, and encountering hard geology could damage the blades. Solutions include: grouting to seal the water, then removing the head head. Using a pipe jacking machine smaller than the existing head head, the machine head was then pushed directly from the working pit into the receiving well 2, with a smaller diameter than the original pipe section 3.

[0036] The construction method when the head of the river-crossing pipe jacking machine is blocked includes the following steps:

[0037] S1. Measure the original pipe jacking machine head obstruction position 5 and the water depth at the obstruction position 5, and set a cofferdam 6 in the river channel above the obstruction position 5;

[0038] S2. After the cofferdam 6 is formed, grouting is performed from the cofferdam 6 to the top and around the receiving well 2 to stop water, and the water in the working well 1 is pumped out to confirm the water-stopping effect;

[0039] S3, cutting a circular hole 8 smaller than the diameter of the original jacking head on the inner end face of the blocked original jacking head, and retaining the outer wall of the original jacking head as a pipe;

[0040] S4. Select a new jacking head 11 with a smaller diameter than the original one. After fixing the new prefabricated pipe on the new jacking head 11, push the new prefabricated pipe from the working well 1. The new jacking head 11 passes through the circular hole 8 cut in S3 and continues construction forward to the receiving well 2.

[0041] S5. Remove cofferdam 6 and restore the river channel.

[0042] Through the above method, the situation where the head of the jacking machine is blocked when crossing the river can be handled at a low cost: grouting is performed through the upper cofferdam 6 to stop water, and the outer wall of the blocked original jacking machine head is used as a pipeline. There is no need to make a new working well above the blocked position 5 to lift out the blocked head, thus avoiding the construction work of excavation and extraction, shortening the construction period and increasing safety.

[0043] Among them, in S1, the cause of the obstruction of the machine head was first investigated. In this example, it was preliminarily determined that the pipe jacking machine head was damaged or hit a hard obstacle. After judging from the debris discharged from the mud on site, it was determined that the debris on site was concrete blocks, steel bar heads, and iron sheet fragments. The machine head in this example was an earth tunneling machine head, and encountering hard geology would cause damage to the machine head blade.

[0044] In S1, the existing riverbed surface is measured to determine the position range of the cofferdam 6. The range of the cofferdam 6 covers the obstructed position 5 of the original jacking head below. At the same time, the riverbed surface elevation at the designed cofferdam position is measured to determine the height of the cofferdam 6 so that the cofferdam 6 is higher than the water surface of the river 4. When constructing the cofferdam 6, water-stopping measures must be taken for the water-facing surface. The cofferdam 6 provides a grouting channel and construction space for the grouting waterstop in S2. In this example, according to the actual situation of the project, sand bags were used to build a cofferdam at the original head stagnation position 5. According to the hydrological calculation results, the water depth during the construction period was 1.258 meters, the silt thickness was 1 meter, and no water level rise protection was considered during the rainy season. The total height of the cofferdam 6 was 2.758 meters and the width was 2.5 meters. The range of the cofferdam 6 was 20 meters in the north-south direction and 15 meters in the east-west direction. The sandbag cofferdam was filled in layers, and the length of the sandbags was determined according to the specific conditions on site. To ensure the water-stopping performance of the cofferdam 6, the water-facing surface of the cofferdam 6 must be fully covered with a water-stop film, which was pressed tightly with small sandbags. The size of the small sandbags was 50*30*20cm.

[0045] In S2, the position, depth, range and grouting pressure of the grouting hole 7 are determined, the grouting hole 7 is drilled downward from the cofferdam 6, and grouting is injected through the grouting hole 7; Figure 1 In the embodiment, the grouting holes 7 are arranged in a matrix on the cofferdam 6; the grouting range covers the upper and outer parts of the blocked position 5 of the original jacking head to form a comprehensive water-stop barrier to prevent water from seeping inward during subsequent construction.

[0046] In S2, this example uses cement-water glass mixed slurry as the grouting material. The grouting material has an adjustable gel time, which can effectively control the diffusion speed and distance of the slurry in the formation, ensuring that the water flow channel is quickly blocked when water flows, and the gel solidification of the slurry is non-toxic and pollution-free; the grouting length starts from 5 meters north of the head position and grouts south to the receiving pit, which is about 63 meters long; the grouting width is 5 meters on both sides of the center line of the jacking pipe, and the grouting depth into the soil is about 10 meters. After the grouting is completed, the water in the working well 1 is pumped out and the grouting water-stopping effect is observed. If the water-stopping effect does not meet the requirements, continue to grout through the grouting holes 7 on the cofferdam 6 to the seepage position of the original jacking head obstruction position 5 until the water-stopping requirements are met.

[0047] In S2, the grouting range includes: from the cofferdam 6 to the receiving well 2, and is not limited to the top and around the blocked position 5. This is because there is a high construction risk of jacking pipes across the river. If the excavation surface becomes unstable and the riverbed collapses, it will cause serious construction accidents. For safety reasons, grouting is performed from the cofferdam 6 to the receiving well 2.

[0048] In S3, in this example, after ensuring the safety of the water-stopping effect, the scrapped components in the current machine head are removed, and the machine head cutter disc cuts a circular hole 8 with a diameter slightly smaller than the original pipe diameter, and the original machine head outer wall is retained to serve as an outer sleeve; before cutting, a small drill is used to drill holes evenly in the machine head to check the water-stopping effect. If the water-stopping effect is not good, the construction personnel will immediately withdraw the machine head and continue to perform dense grouting at the water seepage location. The machine head is dismantled in sections according to the local 1 / 3 range to ensure the water-stopping effect.

[0049] In S3, such as Figure 2 As shown, the lower end of the cut circular hole 8 is inscribed inwardly with the cylindrical outer wall 9 of the original jacking head, and the outer diameter of the new prefabricated pipe is slightly smaller than the circular hole 8. The bottom of the newly jacked prefabricated pipe is in contact with the original prefabricated pipe, avoiding the new prefabricated pipe from being suspended inside the original prefabricated pipe, thereby ensuring the reliability and durability of the new pipe section.

[0050] In S4, based on the on-site debris identified in S1, it was found that the cutter head was damaged by rocks, resulting in obstruction of the head. Therefore, the type of the new pipe jacking head 11 was determined to be a rock head to avoid obstruction due to the aforementioned reasons in subsequent construction. Figure 3 As shown, a new steel prefabricated pipe segment 10 is welded to the rear of a new pipe jacking head 11 through a boot 12. The newly replaced new pipe jacking head 11 and the new steel prefabricated pipe segment 10 are jacked in by a hydraulic jack, and the surrounding stratum 13 is reinforced by grouting.

[0051] Specifically, a laser theodolite is set up at the bottom of the working shaft 1, and the laser is projected onto the target of the manual tunneling tool pipe to ensure that the laser theodolite beam is in a straight line with the center axis of the newly jacked steel prefabricated pipe and the center axis of the original jacking machine head.

[0052] In S4, the new prefabricated pipe is a steel prefabricated pipe, which is strong and durable and can withstand greater pressure than the original pipe section 3. It is connected and fixed to the new jacking head 11 by welding, and multiple sections of steel prefabricated pipes are fixedly connected by welding.

[0053] Specifically, the hydraulic jack in the working well 1 retracts, and a new jacking head 11 with a smaller diameter than the blocked head is replaced and jacking is carried out again: the newly replaced head and the first section of prefabricated tool steel pipe are hoisted into the working well 1, the prefabricated tool steel pipe is welded to the new head through the overshoe 12, and the hydraulic jack is used to jack along the same construction route as the original pipe section 3. After the first section of the steel pipe is jacked, the second section of the steel pipe is welded until it is jacked into the receiving well 2. On the other hand, a flow rate sensor is added to the spiral excavator of the new jacking head 11 to monitor the flow rate in the screw conveyor in real time to warn of a gushing accident. If the flow rate measured by the flow rate sensor exceeds the warning value, the jacking should be stopped immediately and the grouting at the head position should be increased. At the same time, the head movement position should be checked at any time during the jacking process. If it is found that the water inflow in the working well 1 exceeds the warning value, the jacking should also be stopped and the grouting at the head position should be increased immediately. After the water stopping meets the requirements, the jacking should be continued. During this process, the new jacking head is corrected at all times to ensure that the axis of the new jacking head is on the same horizontal line as the circular hole 8 in the old head.

[0054] Since the jacking pipe in this example crosses the river 4, a soil pressure sensor is set in the new jacking machine head 11, and a jacking force sensor is set at the jack. During the jacking process, the soil pressure value in the soil bin and the change value of the jack force are monitored at all times to strictly meet the soil pressure balance condition (as shown in the following formula) and maintain the stability of the excavation surface.

[0055] N f +F f =F p +F s ;

[0056] Ff=πDLfk

[0057] Where:

[0058] N f ——The sum of water and soil pressures at the tunnel face in front of the jacking pipe (kN);

[0059] F f ——Friction force on the jacking pipe (kN);

[0060] F p ——pipe jacking force (kN);

[0061] F s ——Earth pressure in soil bin (kN);

[0062] D——top pipe diameter (m);

[0063] L——pipe jacking length (m);

[0064] f k ——The frictional resistance per unit area between the outer wall of the pipe and the soil (kN / m 2 ).

[0065] In S4, the axis of the new jacking machine head 11 coincides with the center of the circular hole 8 cut out in S3, that is: Figure 1 As shown, a new layer of prefabricated steel pipe segment 10 is added to the original pipe segment 3. The new prefabricated steel pipe segment 10 passes through the circular hole 8 cut in S3 and continues to be pushed forward into the receiving well 2 to complete the construction of the underground pipeline.

[0066] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A construction method for crossing a river when the head of a pipe jacking machine is blocked, characterized in that: The following steps are involved: S1. Measure the obstruction position of the original pipe jacking machine head and the water depth at the obstruction position, and set up a cofferdam in the river channel above the obstruction position; S2. After the cofferdam is formed, grouting is carried out from the cofferdam to the top and around the receiving well to stop water, and the water in the working well is pumped out to confirm the water-stopping effect; S3. Cut a circular hole smaller than the diameter of the original jacking head on the inner end face of the blocked original jacking head, and retain the outer wall of the original jacking head as a pipe; S4: Select a new jacking head with a smaller diameter than the original one, fix the new prefabricated pipe on the new jacking head, and then push the new prefabricated pipe from the working well. The new jacking head passes through the circular hole cut in S3 and continues to move forward to the receiving well. S5. Remove the cofferdam and restore the river channel.

2. The construction method when the head of the river-crossing pipe jacking machine is blocked as claimed in claim 1, characterized in that: In S1, the existing riverbed surface is measured to determine the location range of the cofferdam, which covers the obstructed position of the original jacking pipe head below. At the same time, the riverbed surface elevation at the designed cofferdam location is measured to determine the cofferdam height so that the cofferdam is higher than the river water surface.

3. The construction method when the head of the river-crossing pipe jacking machine is blocked as claimed in claim 1, characterized in that: In S2, the position, depth, range and grouting pressure of the grouting holes are determined according to the water head at the obstructed position, and grouting holes are drilled downward from the cofferdam, and grouting is injected through the grouting holes.

4. The construction method when the head of the river-crossing pipe jacking machine is blocked as claimed in claim 3, characterized in that: The grouting holes are arranged in a matrix on the cofferdam; the grouting range covers the upper and outer parts of the obstructed position of the original jacking head.

5. The construction method when the head of the river-crossing pipe jacking machine is blocked as claimed in claim 1, characterized in that: In S2, cement-water glass mixed slurry is used as the grouting material.

6. The construction method when the head of the river-crossing pipe jacking machine is blocked as claimed in claim 1, characterized in that: In S3, a small drill was used to drill holes evenly on the machine head before cutting to check the water-stopping effect.

7. The construction method for crossing a river when a pipe jacking machine head is blocked according to claim 1, characterized in that: In S3, the lower end of the cut circular hole is inscribed in the cylindrical outer wall of the original pipe jacking machine head, and the outer diameter of the new prefabricated pipe is slightly smaller than the inner diameter of the circular hole.

8. The construction method for crossing a river when the head of the pipe jacking machine is blocked as claimed in claim 1, characterized in that: In S4, the new prefabricated pipe is fixedly connected to the rear of the new jacking head by means of a boot, and the new jacking head and the new prefabricated pipe are jacked in by means of a hydraulic jack.

9. The construction method for crossing a river when the head of the pipe jacking machine is blocked as claimed in claim 8, characterized in that: The new prefabricated pipe is a steel prefabricated pipe, which is connected and fixed to the new jacking machine head by welding, and multiple sections of the steel prefabricated pipe are fixedly connected by welding.

10. The construction method for crossing a river when the pipe jacking machine head is blocked according to claim 1, characterized in that: In S4, the axis of the new jacking head coincides with the center of the circular hole cut in S3; during the jacking process, the new jacking head is constantly corrected to ensure that the axis of the new jacking head is on the same horizontal line as the circular hole in the old head; A flow rate sensor is added to the spiral excavator of the new pipe jacking machine head to monitor the flow rate in the screw conveyor in real time to warn of eruption accidents; a soil pressure sensor is installed in the new pipe jacking machine head, and a jacking force sensor is installed at the jack to monitor the soil pressure value in the soil bin and the change of the jack force at all times during the jacking process; the soil pressure balance condition is met to maintain the stability of the excavation surface.

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