Construction method for treating boulders in pipe jacking construction

Abstract

The invention relates to a boulder treatment construction method in pipe jacking construction, which comprises the following steps of: when a jacking pipe of a pipe jacking machine cannot be normally jacked, returning the pipe jacking machine to a target distance in the direction of a hole; continuous drilling detection is carried out in front of a cutter head of the pipe jacking machine along the tunnel axis and the vertical axis so as to determine the bottom position of a boulder in front of the pipe jacking machine and the diameter of a circumcircle of the boulder; the inner diameter size and the arrangement position of the steel sleeve are determined, so that the steel sleeve corresponding to the inner diameter size sinks to the arrangement position; and after the boulders are cracked and taken out, the steel sleeve is backfilled with clay or gravel soil, and the steel sleeve is pulled out upwards during backfilling till all the steel sleeve is pulled out. The method for taking out the boulders by sinking the steel sleeve is adopted, the boulders can be safely, efficiently and thoroughly removed through the drilling technology, the boulder treatment process and backfilling do not affect follow-up jacking of the pipe jacking machine, and the construction problem that the boulders meet in pipe jacking construction can be effectively solved.

Description

Technical Field

[0001] The present application relates to the technical field of pipe jacking construction in water conservancy projects, and in particular to a method for handling isolated rocks in pipe jacking construction. Background Art

[0002] With the acceleration of domestic infrastructure construction, more and more underground tunnels are constructed using the pipe jacking method, which has the advantages of high safety and fast construction speed. During the pipe jacking process, many problems will be encountered due to changes in geological conditions. For example, if the geology is too hard or too soft, it will have different adverse effects on the pipe jacking. Too hard soil will reduce the jacking speed, and too soft soil will easily cause the machine head to sink.

[0003] There are rock pipe jacking machines and ordinary pipe jacking machines suitable for rock and soil strata in China. However, the current pipe jacking machines are difficult to adapt to boulder strata, and the scope and size of the boulders are difficult to determine through geological exploration before construction. Therefore, it is often found that the jacking machine cannot be pushed in normally after reaching the location of the boulder. Only then can it be determined that there are boulders in the stratum. At this time, the only method is to deal with the boulders and continue jacking.

[0004] In the past, the conventional method for dealing with boulders encountered during pipe jacking was to use a rotary drill to drill holes densely on the ground to remove the boulders. This method has high requirements for the equipment access road and large working space. There is also a method of using water jets to sink the boulders, but this method has the disadvantage that the boulders cannot be completely removed. Or the method of using reinforced concrete to pour the shaft and split the boulders with a splitter has a long construction period and high cost. The method of dealing with boulders is affected by factors such as the size of the boulders, working conditions and economic costs. Under the condition that large equipment has no working space, how to safely, efficiently and economically deal with boulders, and how to deal with them cleanly to ensure the normal jacking of subsequent pipe jacking, is a construction technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] In order to solve or partially solve the problems existing in the related art, the present application provides a method for handling boulders in pipe jacking construction, by sinking a steel casing from the position of the boulder on the ground, using the steel casing as an excavation support structure, removing the boulder from the steel casing, backfilling and removing the steel casing, and resuming pipe jacking after the jacking is completed.

[0006] The first aspect of the present application provides a method for handling boulders in pipe jacking construction, comprising the following steps:

[0007] When the pipe jacking machine cannot push the pipe normally, the pipe jacking machine is retracted toward the hole to the target distance;

[0008] In front of the cutterhead of the pipe jacking machine, continuous drilling detection is carried out along the tunnel axis and the vertical axis to determine the bottom position of the boulder in front of the pipe jacking machine and the circumscribed circle diameter of the boulder;

[0009] Determine the inner diameter of the steel casing according to the diameter of the circumscribed circle of the boulder, and determine the layout position of the steel casing based on the bottom position of the boulder, so as to sink the steel casing corresponding to the inner diameter to the layout position, wherein the steel casing includes multiple sections of detachable steel pipes;

[0010] After the boulders are cracked and removed, clay or gravel is backfilled into the steel casing based on the measured top height of the jacking tunnel, and when the backfill reaches the preset backfill thickness, the steel casing is pulled out upward to a height corresponding to the preset backfill thickness until the steel casing is completely pulled out.

[0011] Among them, retracting the pipe jacking machine to the target distance toward the hole entrance includes:

[0012] Connect the pipe jacking machine to the jacked steel pipe section by section;

[0013] Reaction support shoes are respectively set on the left and right sides of the inner portal wall of the working pit, and force blocks are set on the outer walls of the corresponding steel pipes that have been pushed in;

[0014] A jack cylinder is installed on the reaction support shoe and connected to the hydraulic pump station to push the force block so that the pipe jacking machine and the jacked steel pipe can retreat toward the hole.

[0015] Among them, the reaction support shoe includes an end steel plate, a supporting steel and a clamp. The jack cylinder is fixed to the supporting steel through the clamp. The tail of the supporting steel is close to the end steel plate. The reaction support shoe is fixed to the portal wall through expansion bolts.

[0016] The determination of the bottom position of the boulder and the circumscribed circle diameter of the boulder includes:

[0017] Drill holes at intervals of 0.5m in front of the cutterhead of the pipe jacking machine along the tunnel axis and at intervals of 0.5m on both sides of the vertical axis. Drill holes until no more cores can be taken out. The drilling depth should be at least 1m below the bottom of the tunnel.

[0018] Through the cores taken out, the location, size and range of the boulder are sketched in three dimensions to determine the diameter of the circumscribed circle of the boulder;

[0019] Describe the relative relationship between the boulder, the pipe jacking machine and the tunnel in detail to determine the bottom position of the boulder.

[0020] Among them, the steel casing extraction process includes:

[0021] Backfill soil into the steel casing;

[0022] For every 1m of backfill thickness, pull the steel casing upwards by 1m, repeat the operation until the bottom surface of the first section of the steel casing is exposed to the ground at a height of 0.5 to 1m, and then separate the first section of the steel casing from the second section of the steel casing;

[0023] Repeat the above steps until all the steel casings are removed.

[0024] When the buried depth of the isolated rocks is less than 5m, mechanical removal is adopted. When the buried depth of the isolated rocks is greater than 5m, artificial cracking of the isolated rocks is adopted and vertical lifting is carried out to remove them.

[0025] Among them, the area below 2m above the top of the jacking tunnel is backfilled with clay and compacted layer by layer, with a compaction degree of not less than 90%; the area above 2m above the top of the jacking tunnel is backfilled with sand and gravel and compacted, with a compaction degree of not less than 87%.

[0026] Among them, the steel casing is divided into sections at a height of 5 to 6 meters. When each section of steel pipe sinks to the top 0.5 to 1.0 m from the ground, it is connected to the upper section of steel pipe.

[0027] The technical solution provided by this application may have the following beneficial effects:

[0028] The present application provides a method for handling boulders during pipe jacking construction. When encountering large boulders during the pipe jacking construction, a method of sinking steel casing to remove the boulders is adopted. Drilling technology, online pipe retraction technology and technology for handling boulders inside steel casing are utilized to safely and efficiently remove the boulders, prevent damage to the pipe jacking machine cutter head during the handling of the boulders and ensure thorough removal. No large equipment is required and the boulders are not restricted by access roads and work sites. The application has good economy. The boulder handling process and backfilling have no effect on the subsequent jacking of the pipe jacking machine, and the problem of encountering boulders during pipe jacking construction can be effectively solved.

[0029] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of exemplary embodiments of the present application in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments of the present application.

[0031] Figure 1 It is a schematic diagram of a process of a method for handling boulders in pipe jacking construction shown in an embodiment of the present application;

[0032] Figure 2 It is a side view schematic diagram of the casing sinking treatment of boulders in the pipe jacking construction shown in the embodiment of the present application;

[0033] Figure 3 is a top view schematic diagram of the solitary rock drilling shown in the embodiment of the present application;

[0034] Figure 4 is a side view schematic diagram of boulder drilling shown in an embodiment of the present application;

[0035] Figure 5 is a top view schematic diagram of the top pipe retreat shown in an embodiment of the present application;

[0036] Figure 6 is a schematic side view of the top pipe retreat shown in an embodiment of the present application;

[0037] Figure 7 is a schematic diagram of the reaction support shoe structure shown in an embodiment of the present application;

[0038] Figure 8 is a schematic side view of steel casing extraction shown in an embodiment of the present application;

[0039] Reference numerals:

[0040] In the figure: 1-steel casing, 2-boulder, 3-pipe jacking machine, 4-steel pipe section, 5-geological drilling hole, 6-jack, 7-reaction support shoe, 7.1-end steel plate, 7.2-support steel, 7.3-hoop, 8-load block, 9-portal wall, 10-guide rail, 11-reaction tooling, 12-lifting jack, 13-lifting block, 14-crane. DETAILED DESCRIPTION

[0041] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0042] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0043] In the description of the present application, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0044] Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] The technical solution of the embodiments of the present application is described in detail below with reference to the accompanying drawings.

[0046] like Figure 1 A method for handling isolated rocks in pipe jacking construction is shown, comprising the following steps:

[0047] S1. When the pipe jacking machine cannot push the pipe forward normally, move the pipe jacking machine back to the target distance in the direction of the hole.

[0048] During the operation of the pipe jacking machine in the boulder formation, it was found that the pipe jacking could not be pushed forward normally. It was determined that there were boulders in the formation, and the method of continuing to push forward was adopted after the boulders were dealt with.

[0049] In order to remove the isolated rocks and leave working space, the retraction technology is adopted to retract the pipe jacking machine towards the tunnel entrance by 0.5 to 1.0 m. An online retraction device for the pipe jacking machine is set in the pipe jacking working shaft, which includes reaction support shoes, force blocks, thrust system, tunnel portal walls and pipe sections.

[0050] The pipe jacking machine is welded and connected to the steel pipe sections section by section. A reaction support shoe is installed on each side of the left and right sides of the portal wall in the working shaft. A force block is set at the corresponding position of the outer wall of the jacked steel pipe. A jack cylinder is installed on the reaction support shoe and connected to the hydraulic pump station as a thrust system. The thrust system starts to push the force block and move the pipe section and the pipe jacking machine back toward the tunnel entrance.

[0051] The reaction shoe is composed of an end steel plate, a supporting steel and a clamp. The jack cylinder is fixed to the supporting steel through the clamp, and the tail is close to the end steel plate. The reaction shoe is fixed to the portal wall through expansion bolts, and the top thrust of the jack cylinder is transmitted to the reinforced concrete portal wall of the working shaft through the end steel plate to provide sufficient reaction force.

[0052] The force-bearing block is made of double-pieced I50a I-beams, which are welded to the outer wall of the steel pipe. One is set on each side of the steel pipe and is in a straight line with the cylinder of the reaction support shoe to ensure uniform force.

[0053] like Figure 5 , Figure 6 , Figure 7, a jacking machine retraction device is set along the axis height of the jacking pipe in the jacking well. The retraction device first fixes the reaction support shoe to the tunnel wall through expansion bolts, and one is set on each side of the steel pipe section; a force block is set at the axis height of the steel pipe section 1.5m away from the tunnel wall, and one is set on each side of the steel pipe; then a 200t jack is installed on the reaction support shoe, and the hydraulic pump station is connected. The jack is started, and the jack pushes the force block, driving the jacked steel pipe section to retreat 0.5 to 1.0m outside the tunnel through the guide rail set under the pipe section. The end steel plate of the reaction support shoe is made of 3mm thick steel plate, the supporting steel is made of I50 I-beam, and the hoop is made of 0.5 thick steel bar, all of which are welded together; the force block is made of double-piece I50 I-beam, with a length of 0.3 to 0.5m, and is welded to the outer wall of the jacking steel pipe.

[0054] S2. In front of the cutterhead of the pipe jacking machine, continuous drilling detection is carried out along the tunnel axis and the vertical axis to determine the bottom position of the boulder in front of the pipe jacking machine and the circumscribed circle diameter of the boulder.

[0055] Based on the continuous drilling method, continuous drilling detection is carried out in front of the cutter head of the pipe jacking machine along the tunnel axis and the vertical axis. Holes are drilled at intervals of 0.5m at 0.5m, 1.0m, 1.5m... in front of the cutter head of the pipe jacking machine along the tunnel axis, and holes are drilled at intervals of 0.5m at 0.5m, 1.0m, 1.5m... on both sides of the vertical axis. The drilling depth is at least 1m below the bottom of the tunnel, and each hole is drilled until no more core is taken out.

[0056] like Figure 3 , Figure 4 , continuous drilling detection is carried out in front of the pipe jacking machine cutterhead along the tunnel axis and the vertical axis, and geological drilling is carried out at 0.5m, 1.0m, and 1.5m in front of the pipe jacking machine cutterhead along the tunnel axis direction, and 0.5m, 1.0m, and 1.5m on both sides of the vertical axis direction. The drilling depth is at least 1m below the bottom of the tunnel, and each hole is drilled until no rock core is taken out. Through the taken out rock core, a three-dimensional sketch of the position, size, and range of the boulder is made, and the relative relationship between the boulder and the pipe jacking machine and the tunnel is described in detail, and the plane position of the boulder is marked on the ground. A circle with a diameter of 2.8m is measured and released on the ground with the centroid of the boulder, and white lime is used to mark it. The ground concrete is broken with the circle at the mark.

[0057] S3. Determine the inner diameter of the steel casing according to the diameter of the circumscribed circle of the boulder, and determine the layout position of the steel casing based on the bottom position of the boulder, so as to sink the steel casing corresponding to the inner diameter to the layout position.

[0058] At the location of the isolated rock on the ground, a steel casing is installed. The inner diameter of the steel casing is 1 to 2 meters larger than the diameter of the circumscribed circle of the isolated rock. Soil is removed from the casing, and the steel casing is sunk by its own weight while the soil is removed until the steel casing sinks to the bottom of the isolated rock and reaches the installation position. The steel casing can be divided into sections at a height of 5 to 6 meters according to the sinking depth. Connecting steel plates are set on the inner wall of each section of the casing for welding to ensure the integrity of the casing and facilitate disassembly and removal when the casing is removed later. When each section of the casing sinks to a top of 0.5 to 1.0 meters from the ground, the previous section of the casing is connected.

[0059] like Figure 2 , use an excavator to dig 1.5 to 2.0 m deep along the broken ground range, and then stop excavating; use a 50t crane to lift the first section of steel casing into the pit. Each section of steel pipe is 6 meters long, 2.8 m in diameter, 36 mm thick, and made of Q355C; extend the long-arm excavator into the steel casing to continue to remove the soil in the pipe. Pay attention to uniformity and symmetry during excavation to make the steel casing sink evenly; when the first section of steel casing sinks to the distance of 0.5 to 1.0 m from the ground, stop excavating and sinking, and install the second section of steel casing. In order to facilitate the decomposition of the steel casing in the later stage and reduce the sinking resistance of the steel casing, 6 ribs are welded and connected on the inner wall of the steel pipe; after the steel pipe connection is completed, continue to excavate and sink until the bottom of the steel pipe sinks to the bottom of the boulder.

[0060] S4. After the isolated rocks are cracked and removed, clay or gravel soil is backfilled into the steel casing based on the measured top height of the jacking tunnel, and when the backfilling reaches the preset backfill thickness, the steel casing is pulled out upward to a height corresponding to the preset backfill thickness until the steel casing is completely pulled out.

[0061] When the boulders are buried less than 5m deep, they can be broken mechanically. When the boulders are buried more than 5m deep, they can be manually broken and lifted out vertically. The boulders are broken by hammers or manually. When breaking them manually, a row of holes with a diameter of 2cm are pre-punched on the surface of the boulders, steel pins are inserted into the holes, and the steel pins are repeatedly hammered one by one with a sledgehammer to break the boulders into small pieces that can be carried manually, and then they are lifted vertically out of the ground by a crane.

[0062] After the isolated rock is removed, backfill the casing with soil. For every 1m of backfill thickness, pull the steel casing up 1m. Repeat the operation until the bottom surface of the first section of steel casing is exposed 0.5 to 1m above the ground. Then disassemble and separate the first and second sections of the steel casing, and continue to remove the remaining steel casing according to this process. When removing the steel casing, a hydraulic jacking device is used in conjunction with a crane. The hydraulic jacking device serves as the main force transmission system for pulling out the steel casing. The crane holds the top of the steel casing and lifts out the disassembled sections of the steel casing.

[0063] The hydraulic jacking device consists of a reaction tooling, a jacking jack and a jacking block. 4 to 6 jacking blocks are evenly arranged around the outer wall of the steel casing. The jacking blocks are made of I50a steel and welded to the outer wall of the steel casing. A jacking block is arranged every 1.5m to 2.0m vertically on the steel casing. Every time the steel casing is pulled up 1.5 to 2.0m, the jacking block is welded.

[0064] A lifting jack is arranged below the lifting block, and the jack is connected to the hydraulic pump station to provide the thrust for lifting. A reaction tooling is arranged below the lifting jack, and the reaction tooling is supported on the ground to provide the reaction force for lifting.

[0065] When backfilling soil in the steel casing, clay is backfilled in the area below 2m from the top of the jacking tunnel and compacted layer by layer with a compaction degree of not less than 90% to ensure the stability of the soil when the jacking pipe is subsequently resumed. Sand and gravel are backfilled in the area above 2m from the top of the jacking tunnel and compacted with a compaction degree of not less than 87% to ensure that the ground does not experience subsequent settlement.

[0066] like Figure 8 After the boulders are removed, clay is backfilled in the area below 2m from the top of the jacking tunnel and compacted in layers with a compaction degree of not less than 90% to ensure the stability of the soil when the jacking is resumed. Sand and gravel are backfilled in the area above 2m from the top of the jacking tunnel and compacted with a compaction degree of not less than 87%; the backfill soil is filled in layers of 50cm and compacted layer by layer with a small compactor to prevent stratum collapse and ground slurry during the later jacking process. For every 1m of backfill, the steel casing is pulled up 1m, and the operation is repeated until all the steel casings are pulled out.

[0067] like Figure 8 During the steel casing extraction process, 8 hydraulic jacking devices are evenly arranged around the outer wall of the steel casing. For the hydraulic jacking device, first, 8 jacking blocks are welded outside the pipe wall, 1m away from the ground, and a 50t jacking jack is installed below, and the hydraulic pump station is connected. The pump station is started, and the jacking jack is extended, and the jacking block is pushed to drive the steel casing to rise, and the steel casing is pulled out 0.5m. At this time, the jacking jack is recovered, and a 0.5m high reaction tooling is placed under the jacking jack, and the steel casing is lifted again, and the steel casing is pulled out 0.5~1.0m. The operation is repeated until all the steel casing is pulled out. In this process, a 50t crane is used to lift the upper end of the steel casing, and force is applied to prevent the steel casing from tilting. Both the jacking block and the reaction tooling are made of I50 I-beam.

[0068] After the steel pipes are pulled out and the clay is backfilled, the ground is hardened and jacking is resumed.

[0069] Finally, it should be noted that, in this article, relationships such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms include, include or any other variations are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0070] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0071] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0072] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application.

[0073] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A method for handling isolated rocks in pipe jacking construction, characterized in that: include: When the pipe jacking machine cannot push the pipe normally, the pipe jacking machine is retracted toward the hole to the target distance; In front of the cutterhead of the pipe jacking machine, continuous drilling detection is carried out along the tunnel axis and the vertical axis to determine the bottom position of the boulder in front of the pipe jacking machine and the circumscribed circle diameter of the boulder; Determine the inner diameter of the steel casing according to the diameter of the circumscribed circle of the boulder, and determine the layout position of the steel casing based on the bottom position of the boulder, so as to sink the steel casing corresponding to the inner diameter to the layout position, wherein the steel casing includes multiple sections of detachable steel pipes; After the boulders are cracked and removed, clay or gravel is backfilled into the steel casing based on the measured top height of the jacking tunnel, and when the backfill reaches a preset backfill thickness, the steel casing is pulled out upward to a height corresponding to the preset backfill thickness until the steel casing is completely pulled out.

2. The method for handling boulders in pipe jacking construction according to claim 1, characterized in that: The step of retracting the pipe jacking machine toward the hole to the target distance includes: Connect the pipe jacking machine to the jacked steel pipe section by section; Reaction support shoes are respectively arranged on the left and right sides of the inner portal wall of the working pit, and force blocks are arranged on the outer walls of the corresponding steel pipes that have been pushed in; A jack cylinder is mounted on the reaction support shoe and connected to a hydraulic pump station to push the force block so that the pipe jacking machine and the pushed-in steel pipe are retreated toward the hole.

3. The method for handling boulders in pipe jacking construction according to claim 2, characterized in that: The reaction support shoe comprises an end steel plate, a supporting steel and a clamp, the jack cylinder is fixed to the supporting steel through the clamp, the tail of the supporting steel is close to the end steel plate, and the reaction support shoe is fixed to the portal wall through expansion bolts.

4. The method for handling boulders in pipe jacking construction according to claim 1, characterized in that: The determination of the bottom position of the boulder and the circumscribed circle diameter of the boulder includes: Drill holes at intervals of 0.5m in front of the cutterhead of the pipe jacking machine along the tunnel axis and at intervals of 0.5m on both sides of the vertical axis. Drill holes until no more cores can be taken out. The drilling depth should be at least 1m below the bottom of the tunnel. Through the cores taken out, the location, size and range of the isolated rocks are sketched in three dimensions to determine the circumscribed circle diameter of the isolated rocks; The relative relationship between the boulder, the pipe jacking machine and the tunnel is described in detail to determine the bottom position of the boulder.

5. The method for handling boulders in pipe jacking construction according to claim 1, characterized in that: The extraction process of the steel casing comprises: Backfilling soil into the steel casing; For every 1m of backfill thickness, pull the steel casing upwards by 1m, repeat the operation until the bottom surface of the first section of the steel casing is exposed to a height of 0.5 to 1m above the ground, and then separate the first section of the steel casing from the second section of the steel casing; Repeat the above steps until all the steel casings are removed.

6. The method for handling boulders in pipe jacking construction according to claim 1, characterized in that: When the buried depth of the isolated rocks is less than 5m, mechanical removal is adopted. When the buried depth of the isolated rocks is greater than 5m, artificial cracking of the isolated rocks is adopted and vertical lifting is carried out.

7. The method for handling boulders in pipe jacking construction according to claim 1, characterized in that: The top pipe tunnel with a height below 2m is backfilled with clay and compacted in layers with a compaction degree of not less than 90%; the top pipe tunnel with a height above 2m is backfilled with sand and gravel and compacted with a compaction degree of not less than 87%.

8. The method for handling boulders in pipe jacking construction according to claim 1, characterized in that: The steel casing is divided into sections at a height of 5 to 6 m. When each section of the steel pipe sinks to a top 0.5 to 1.0 m above the ground, it is connected to the upper section of the steel pipe.

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