Construction method for removing intruding obstacles in the form of wall bodies in a diaphragm wall

Abstract

The application provides a construction method for removing wall body type obstacles in a diaphragm wall, comprising: obstacle positioning and parameter collection; construction preparation and equipment adaptation; mud protection wall; rotary drilling rig driving the casing to carry out downward cutting operation until the casing approaches the top surface of the obstacle; obstacle segmentation and layering, using the rotary drilling rig to carry out non-discriminatory obstacle removal and soil taking in the full wrapping range of the casing by using different drill bits; casing removal; sawtooth-shaped corner obstacle cleaning; groove forming machine cooperates with slag cleaning and groove wall trimming; process handover. The application realizes the layering, segmentation, transverse cutting and efficient removal of wall body type obstacles by integrating a transverse cutting positioning structure, a layering operation control component and a cooperative breaking mechanism, and solves the problems of incomplete destruction, large equipment loss and high safety risk of existing equipment.

Description

Technical Field

[0001] This invention belongs to the field of building construction technology, and in particular relates to a construction method for removing wall-type encroachment obstacles inside diaphragm walls. It is an integrated method for layered and segmented horizontal cutting and coordinated removal of various types of rigid wall-type encroachment obstacles (including residual walls, continuous mixing pile walls, masonry walls, etc.) during the construction of diaphragm walls. It can be adapted to the removal of obstacles in the trenches of underground continuous walls under various geological conditions such as soft soil, silty clay, sand, and rock strata. Background Technology

[0002] In urban renewal, engineering expansion, and the construction of new deep foundation pit diaphragm walls, wall-type encroachment obstacles (such as existing brick and stone walls, three-axis mixing pile water-stop curtains, and continuous concrete retaining walls) are extremely common. These obstacles are characterized by strong continuity, good structural integrity, high strength, and large burial depth. They overlap deeply with the diaphragm wall construction area, directly hindering trenching operations and concrete pouring, seriously affecting construction progress and project quality.

[0003] Existing obstacle removal equipment has significant structural defects: First, traditional rotary drilling rigs only have single-point vertical drilling capabilities and lack a dedicated positioning and spacing adjustment structure for horizontal cutting, making it impossible to form a regular group of holes to break through the integrity of the wall, resulting in incomplete cleaning and a lot of residue; Second, trenching machines are not equipped with layered cutting components adapted to the horizontally cut blocks, resulting in high resistance and severe tool wear when directly cutting the complete wall, and lacking a collaborative adaptation mechanism for inter-layer operations; Third, existing equipment lacks a standardized layered and segmented operation control structure, resulting in a disordered destruction process, significant disturbance to the surrounding soil, high safety risks, and inability to accurately control the drilling spacing and layer height, leading to poor adaptability.

[0004] Therefore, there is an urgent need for a structurally sound obstacle removal method that integrates a lateral cutting and positioning structure, layered operation control components, and a collaborative demolition mechanism to achieve layered and segmented lateral cutting and efficient removal of wall-type obstacles, thereby solving the problems of incomplete destruction, high equipment wear and tear, and high safety risks associated with existing equipment. Summary of the Invention

[0005] To address the problems of existing wall-type obstacle removal equipment, such as the lack of a dedicated lateral cutting structure, low precision in layered and segmented control, poor coordination, and incomplete destruction, this invention provides a construction method for removing wall-type encroachment obstacles within diaphragm walls. By integrating a precise positioning and cutting mechanism, layered operation control components, a collaborative demolition and debris removal mechanism, and a protective limiting mechanism, it achieves precise control of the tangential drilling for obstacle removal and layered operations of 4-5m, thoroughly cutting the integrity of the wall. Then, the collaborative demolition mechanism efficiently removes the obstruction, ensuring the stability of the borehole wall and the quality of construction, while reducing equipment wear and safety risks.

[0006] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0007] A construction method for removing encroachment obstacles from the inner wall of a diaphragm wall includes the following steps:

[0008] Step 1: Obstacle localization and parameter acquisition;

[0009] Step 2: Construction preparation and equipment adaptation;

[0010] Step 3: Mud wall protection;

[0011] Step 4: The rotary drilling rig drives the casing to press down and cut until the casing is close to the top surface of the obstacle;

[0012] Step 5: Divide the obstacles into horizontal segments and vertical layers, disconnect the casing driver from the casing, and use a rotary drilling rig with different drill bits to perform indiscriminate obstacle removal and soil extraction within the entire casing enclosure, removing the obstacles inside the casing along with the original soil.

[0013] Step 6: Remove the casing;

[0014] Step 7: Clear jagged corner obstacles;

[0015] Step 8: The tank forming machine assists in slag removal and tank wall trimming;

[0016] Step 9: Process handover.

[0017] Furthermore, in step 1, GPS positioning and total station verification are used to determine the coordinates of underground obstacles, and the planar projection outline of the obstacles is simultaneously marked on the top surface of the guide wall and the ground. For shallow obstacles with a burial depth ≤ 3m, excavators and manual labor are used to remove the surface coverings of the obstacles, and the obstacle parameters are measured manually. For deep obstacles with a burial depth > 3m, a trenching machine is used to grab the probe location, and the horizontal distribution boundary of the obstacle is determined by the grabbed slag sample. A lightweight dynamic penetrometer is used to determine the vertical burial depth and bottom elevation of the obstacle. For wall-type obstacles, small strain testing is used to determine the strength, integrity, and internal reinforcement of the obstacle. A parameterized database is established, and the work area is delineated.

[0018] Furthermore, in step 4, the casing is a segmented, extendable type, with the first segment being a steel casing with a cutting edge, and the rest being ordinary casings; the specific process of step 4 includes:

[0019] Connect the rotary drilling rig's power head to the casing driver. Then, first coaxially connect the steel casing with cutting edges to the casing driver. After docking, lock it with a flange to ensure that the steel casing with cutting edges, the casing driver, and the power head are completely coaxial. Start the rotary drilling rig's power head, and drive the steel casing with cutting edges to rotate at a low speed through the casing driver while slowly applying downward pressure. The steel casing with cutting edges will cut the strata. When the steel casing with cutting edges is pressed down to 50cm from the top surface of the guide wall, stop rotating and pressing down. Temporarily fix the steel casing with cutting edges to the borehole opening, disconnect the casing driver from the steel casing with cutting edges, hoist the next section of ordinary casing, and connect the ordinary casing to the steel casing with cutting edges, adding a sealing gasket at the joint. After the extension is completed, reconnect the casing driver and continue the downward cutting operation. Repeat this process until the casing is close to the top surface of the obstacle.

[0020] Furthermore, in step 5, the horizontal segmentation involves dividing the work into sections according to the width of the trench formed by the ground wall, with each section being 4 to 6 meters long. The obstacles within a single trench section are divided in one go, and clear boundary markers are set between each section. For extra-long obstacles, a skip-section construction method is adopted to avoid mutual disturbance between adjacent sections. The vertical layering involves dividing the work into layers according to the geological features, the length of a single section of the casing, and the burial depth of the obstacle, with the height of each layer controlled at 4 to 5 meters. The top and bottom elevations of the obstacles are set up separately to ensure full height coverage of the obstacles.

[0021] Furthermore, in step 5, the appropriate drill bit is selected based on the strength of the obstacle and the properties of the soil layer. For miscellaneous fill and sandy soil layers, a sand scoop is used; for cohesive soil and silty soil, a body drill is used; and for clearing obstacles in harder rock layers, a barrel drill is used for cutting and breaking. First, the obstacle is cut around the ring with the ring-shaped cutting teeth of the barrel drill to form a ring-shaped free surface. Then, the obstacle in the core area is broken with a breaking drill bit. Finally, the sand scoop is used to remove all the debris. At the same time, during the operation in the hole, the mud level is kept stable. If the mud level drops due to soil removal, mud is added immediately. It is strictly forbidden for the mud level to fall below the control elevation.

[0022] Further, step 6 includes:

[0023] After the soil removal in the hole is completed, the rotary drilling rig power head is reconnected to the casing driver, and the casing driver is connected to the top of the casing. Then, the hole depth is checked with a measuring rope to confirm that there are no large pieces of sediment or obstacles stuck in the casing. The mud performance indicators and liquid level in the hole are checked, and mud is added to the control elevation to ensure that the wall protection effect meets the standard. High-quality bentonite mud is injected into the gap between the outer wall of the casing and the soil through the grouting pipe to form a lubricating isolation layer and reduce the frictional resistance of the casing lifting.

[0024] Segmented extraction: Start the rotary drilling rig's power head to drive the casing to rotate alternately in both directions at low speed, while slowly applying extraction force. The initial extraction force should be controlled within 1.2 times the casing's own weight. When the casing becomes loose and shifts upward, gradually increase the extraction force. The maximum extraction force should not exceed 70% of the rotary drilling rig's rated extraction force. The extraction height should be controlled within three-quarters of the length of a single casing section. Then, pause extraction, keep the casing rotating for a period of time, inject lubricating mud again, and then continue extraction until the flange of the casing section protrudes 50cm from the borehole opening. Stop extraction, temporarily fix the lower casing to the borehole opening, remove the flange connecting bolts, completely pull out the casing section, and hoist it to the designated area. Repeat this process to remove all casing sections one by one.

[0025] Furthermore, during the casing extraction process, a designated person simultaneously replenishes mud into the hole, with the mud replenishment speed perfectly matched to the casing extraction speed. This ensures that the mud level in the hole remains stable within 30cm below the top surface of the guide wall, and prevents a significant drop in the mud level or the formation of negative pressure inside the hole. After the casing is extracted, immediately clean the inner and outer walls of the casing of any debris and cement lumps. Inspect the roundness of the casing, the welds, the connecting clips, and the wear of the cutting edges. Repair any deformed or damaged parts. After successful repair, the casings are classified and stored for recycling. Casings that cannot be repaired are scrapped.

[0026] Further, step 7 includes:

[0027] After the casing is cut and cleared, if serrated edges and corners remain along the trench wall, the casing drill is used for segmented and layered drilling. When the casing drill is difficult to remove, it is modified by welding a shovel plate to one side of the casing drill. The shovel plate is made of 20mm thick steel plate and is then cut and removed, ensuring that the shovel plate edge is completely in contact with the serrated obstacles on both sides of the trench wall. The rotary drilling rig drives the casing drill to rotate and cut vertically along the trench wall in segments. The cutting height of a single operation does not exceed 2m. The lateral cutting force of the shovel plate is used to completely scrape off and cut the protruding serrated obstacles. After cutting, the debris is grabbed and discharged using a sand scoop to prevent debris from settling at the bottom of the hole and affecting subsequent operations.

[0028] Further, step 8 includes:

[0029] The trenching machine is positioned in the corresponding layered and segmented area, and a "top-down, layered and segmented, three-stage slag removal" process is adopted. The layering height is consistent with the previous obstacle removal layering height. Each segment is divided into three positions: left, middle and right, for slag removal in sequence until the design bottom elevation of the trench segment is reached. At the same time, the mud parameters in the trench are maintained to ensure the stability of the borehole wall. After trenching, the flatness of the trench wall meets the requirements for diaphragm wall construction.

[0030] The present invention has the following beneficial effects:

[0031] Thorough obstacle removal and controllable quality: By combining "full casing drilling and segmentation" with "dedicated drill bit trimming," continuous wall obstacles are completely transformed into independent fragments and removed, solving the problem of residual jagged obstacles left by traditional methods. Ultimately, key indicators such as the flatness and verticality of the trench wall meet the required specifications.

[0032] Construction safety and minimal disturbance: The use of full casing ensures complete enclosure of the drilling area, effectively preventing the risk of borehole wall collapse during obstacle removal. The layered, segmented, and sequential operation mode reduces instantaneous large-scale disturbance to the surrounding soil.

[0033] High efficiency and reduced costs through collaborative operation: Rotary drilling rigs are responsible for efficient drilling and soil extraction, while trenching machines handle precise debris removal and wall repair. Their collaborative work fully leverages the advantages of each equipment, significantly improving obstacle removal efficiency. Compared to direct cutting or large-scale excavation and backfilling, this method results in lower equipment wear and lower overall costs.

[0034] Wide applicability: This method is not only applicable to various wall-type obstacles (concrete walls, mixing pile walls, brick and stone walls, etc.), but its layered and segmented control logic can also flexibly adapt to the removal of obstacles of different burial depths and intensities, and has broad application value. Attached Figure Description

[0035] Figure 1 This is a flowchart of the construction method for removing encroachment obstacles in the inner wall of a diaphragm wall as described in this invention;

[0036] Figure 2 This is a schematic diagram of the rotary drilling rig described in this invention;

[0037] Figure 3 This is a schematic diagram of the trenching machine described in this invention;

[0038] Figure 4 This is a schematic diagram of the sleeve driver described in this invention;

[0039] Figure 5 This is a schematic diagram of the steel casing with cutting edge described in this invention;

[0040] Figure 6 This is a schematic diagram of a common protective sleeve as described in this invention;

[0041] Figure 7 This is a schematic diagram of the tubular drill described in this invention;

[0042] Figure 8 This is a schematic diagram of the body drilling described in this invention;

[0043] Figure 9 This is a schematic diagram of the sand dredging bucket described in this invention;

[0044] Figure 10 This is a schematic diagram of underground obstacles.

[0045] In the diagram: 1-Obstacle; 2-Rotary drilling rig; 3-Trenching machine; 4-Casing driver; 4a-Driver connection port; 4b-First positioning groove and stop; 6-Steel casing with cutting edge; 8-Ordinary casing; 8a-Second positioning groove and stop; 9-Casing drill; 9a-Shovel plate; 10-Body drilling; 11-Sand scoop bucket. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0047] Example 1:

[0048] Reference Figure 1 As shown, the construction method for removing encroachment obstacles in the inner wall of a diaphragm wall according to the present invention includes the following process:

[0049] Step 1: Location and parameter acquisition of obstacle 1;

[0050] like Figure 10 As shown, when obstacle 1 is discovered during the construction of the ground wall, GPS positioning and total station verification are used to determine the coordinates of underground obstacle 1. Simultaneously, the planar projection outline of obstacle 1 is marked on the top surface of the guide wall and the ground. For shallow obstacles (burial depth ≤ 3m), the surface covering of obstacle 1 is removed using an excavator and manual labor until obstacle 1 is exposed. The width, length, and exposed height of obstacle 1 are measured manually with a tape measure, and information such as material type is recorded. For deep obstacles (burial depth > 3m), a trenching machine 3 is used to grab probes. The horizontal distribution boundary of obstacle 1 is determined by the grabbed slag samples. Then, a lightweight dynamic penetrometer is used to set up probe points along the direction of obstacle 1 to determine the vertical burial depth and bottom elevation of obstacle 1. For wall-type obstacles (such as high-strength concrete or reinforced concrete walls), small strain testing and other methods are used to determine the strength, integrity, and internal reinforcement of obstacle 1. A parameterized database is established, and the work area is delineated.

[0051] Step 2: Construction preparation and equipment adaptation;

[0052] Choose such Figure 2 , 3 The rotary drilling rig 2, which meets the power requirements for drilling and breaking, and the hydraulic trenching machine 3, which meets the requirements for obstacle clearing efficiency, are shown. Both are equipped with a sectional, extendable casing (the first section of the casing is as follows). Figure 5 The steel casing 6 with cutting edges shown is as follows: the remaining sections are... Figure 6 The ordinary casing shown is 8), and the matching is as follows: Figure 4 The shown casing driver 4, and drill bit kit including annular cutting tooth drill bit, split-type breaker drill bit, etc.;

[0053] The casing uses the same thickness and diameter as the diaphragm wall trench section to ensure complete coverage for overall removal; the torque of the main body of the rotary drilling rig is ≥400kNm; (e.g., ...) Figure 7 , 8 As shown in Figures 9 and 1, the drill bits selected are sand scoop 11, tubular drill 9, and body drill 10, which are 10cm smaller than the diameter of the casing, as well as tubular drill 9 with the same diameter as the casing and tubular drill 9 with a shovel 9a, so as to be suitable for obstacle removal under different soil layers and working conditions.

[0054] Step 3: Mud wall protection;

[0055] Bentonite slurry was prepared in advance in the trench section. Before the obstacle removal operation, the prepared slurry was injected into the trench section in advance, and the slurry level was ensured to be no less than 30cm below the top surface of the guide wall. During the operation, slurry was replenished at any time according to the progress of obstacle removal to ensure the wall protection effect.

[0056] Step 4: Casing installation and verticality control;

[0057] The power head of the rotary drilling rig 2 is rigidly connected to the drive connection port 4a on the upper part of the casing drive 4 by a pin, ensuring that it is coaxial with the power head. The pin is fully inserted and locked, and its diameter must match the diameter of the casing. Then, the first section of the steel casing 6 with the cutting edge is coaxially connected to the first positioning groove and stop 4b provided on the lower part of the casing drive 4. After the connection is completed, it is locked with a flange to ensure that the steel casing 6 with the cutting edge, the casing drive 4, and the power head are completely coaxial, and the coaxiality deviation is ≤2mm.

[0058] During construction, the power head of the rotary drilling rig 2 is started, and the steel casing 6 with cutting edge is driven to rotate at low speed through the casing driver 4. At the same time, downward pressure is slowly applied to allow the steel casing 6 with cutting edge to cut the strata. The verticality of the steel casing 6 with cutting edge is monitored and controlled by the drilling rig's built-in electronic monitoring system.

[0059] When the first section of the steel casing 6 with the cutting edge is pressed down to a certain position, stop rotating and pressing down, temporarily fix the steel casing 6 with the cutting edge to the orifice, disconnect the casing driver 4 from the steel casing 6 with the cutting edge, hoist the next ordinary casing 8, connect the ordinary casing 8 and the steel casing 6 with the cutting edge through the flange fastener to the second positioning groove and stop 8a on the ordinary casing 8, tighten the bolts symmetrically and evenly, add sealing gaskets at the joint, and the joint gap ≤2mm; after the extension is completed, reconnect the casing driver 4 and continue the pressing and cutting operation, repeat this process until the casing is close to the top surface of the obstacle 1.

[0060] Step 5: Precisely destroy obstacle 1 in segments and layers;

[0061] Horizontal segmentation: Along the direction of the wall-shaped obstacle, divide the work into sections according to the width of the trench formed by connecting the ground and the wall. The length of a single section should be 4 to 6 meters. Obstacle 1 within a single trench section is divided in one go, and clear boundary markers are set between each section. For extra-long obstacle 1, skip-section construction is adopted to avoid mutual disturbance between adjacent sections.

[0062] Vertical layering: Based on the geological features, the length of a single section of the casing, and the burial depth of obstacle 1, vertical layers are divided, with the height of a single layer controlled between 4 and 5 meters. The top and bottom elevations of obstacle 1 must be set up separately to ensure full coverage of obstacle 1.

[0063] Before clearing obstacles, the center point, hole boundary, and layer depth control line of each section of the casing must be marked on the top surface of the guide wall and around the trench section by using steel bar ends and spray paint. The holes must be tangent to each other, and gaps that cause obstacles to remain are strictly prohibited.

[0064] During the clearing process, each section is cleared by sequentially lowering a casing of the same thickness and diameter as the wall, forming several tangent circular holes, and then clearing the obstacles inside the hole is completed in sections and layers. After the casing is pressed into place, the connection between the casing driver 4 and the casing is disconnected, the corresponding drill bit is replaced, and the rotary drilling rig 2 is equipped with different drill bits such as the sand scoop 11, the casing drill 9, and the body drill 10 to carry out indiscriminate clearing and soil removal within the entire enclosed area of ​​the casing, removing the obstacles 1 inside the casing along with the original soil.

[0065] The basic logic of obstacle removal is "casing first, soil removal later". When the casing cannot be installed in one go, the method of drilling, splicing and soil removal are carried out simultaneously until the design depth is reached. The initial section of the casing is inserted into the soil by controlling the speed and torque of the rotary drilling rig 2 to prevent the casing 8 from deviating. If deviation occurs, it is corrected dynamically by hydraulic correction or adjusting the drilling parameters. The upper and lower sections of the casing 8 are fixed with bolts, and the joint gap is ≤2mm. The corresponding drill bit is selected according to the strength of the obstacle and the properties of the soil layer. When it is a mixed fill or sandy soil layer, the sand scoop 11 can be used. When it is a cohesive soil or silty soil, the body drill 10 can be used. When clearing obstacles in relatively hard rock layers, the casing drill 9 can be used for cutting and breaking. First, the ring-shaped cutting teeth of the casing drill 9 are used to cut the obstacle to form a ring-shaped free surface. Then, the breaking drill bit is used to break the obstacle in the core area. Finally, the sand scoop 11 is used to remove all the debris. When working inside the borehole, it is essential to ensure that the mud level remains stable. If soil removal causes the mud level to drop, mud must be replenished immediately. It is strictly forbidden for the mud level to fall below the control elevation.

[0066] Step 6: Remove the casing;

[0067] Release the casing lock: After the soil removal in the hole is completed, reconnect the rotary drilling rig 2 power head to the casing driver 4. The casing driver 4 is locked to the top of the casing. Check the firmness of the connection and confirm that there is no risk of loosening or disengagement.

[0068] Hole condition inspection: Use a measuring rope to verify the hole depth and confirm that there are no large pieces of sediment or obstructions blocking the casing; check the mud performance indicators and liquid level in the hole, and add mud to the control elevation to ensure that the wall protection effect meets the standard;

[0069] Lubrication preparation: High-quality bentonite slurry is injected into the gap between the outer wall of the casing and the soil through the grouting pipe to form a lubricating isolation layer and reduce the frictional resistance of the casing during lifting; the grouting volume is determined according to the burial depth of the casing, and the grouting volume of a single casing section is not less than 0.5m³.

[0070] Segmented lifting construction: Strictly adhere to the principles of "segmented lifting, replenishment as you lift, and low-speed and stable operation," and strictly prohibit lifting the entire length at once to avoid negative pressure collapse of the borehole wall;

[0071] During the lifting operation, start the power head of the rotary drilling rig 2, driving the casing to rotate alternately in both directions at a low speed of 3-5 r / min. Simultaneously, slowly apply the lifting force, initially controlling it to be within 1.2 times the casing's own weight. When the casing becomes loose and shifts upward, gradually increase the lifting force, ensuring the maximum lifting force does not exceed 70% of the rated lifting force of the rotary drilling rig 2. When a single casing section is 4m long, control the single lifting height to within 3m, pause the lifting, maintain the casing rotation for 30 seconds, inject lubricating mud again, and then continue lifting until the flange of that casing section protrudes 50cm from the borehole opening. Stop the lifting, temporarily fix the lower casing to the borehole opening, remove the flange connecting bolts, completely pull out the casing section, and hoist it to the designated area. Repeat this process to remove all casing sections one by one.

[0072] During the casing lifting process, a designated person should simultaneously replenish the hole with mud, ensuring that the mud replenishment speed is perfectly matched with the casing lifting speed. This will ensure that the mud level in the hole remains stable within 30cm below the top surface of the guide wall, and prevent any significant drop in mud level or the formation of negative pressure in the hole.

[0073] After the casing is removed, immediately clean the slag and cement lumps from the inner and outer walls of the casing. Check the roundness of the casing, the welds, the connecting clips, and the wear of the cutting edges. Repair any deformed or damaged parts. After repair, the casings should be classified and stored for recycling. Casings that cannot be repaired should be scrapped and must not be used again.

[0074] Step 7: Clear jagged corner obstacles;

[0075] Because serrated edges and corners of the trench wall remained after the casing was cut and cleared, the spool drill 9 was used for segmented and layered drilling. When the spool drill 9 was difficult to clear, it was modified by welding a shovel plate 9a to one side of the spool drill 9. The shovel plate 9a was made of 20mm thick steel plate and then cut and cleared it, ensuring that the cutting edge of the shovel plate 9a was completely in contact with the serrated obstacles on both sides of the trench wall. The diameter of the drill bit was consistent with the design thickness of the diaphragm wall. The rotary drilling rig 2 drove the spool drill 9 to rotate at a speed of 8-12 r / min. It cut vertically along the trench wall in segments, with a single cutting height not exceeding 2m. The lateral cutting force of the shovel plate 9a was used to completely scrape off and cut and break up the protruding serrated obstacles. After the cutting process, the sand hopper 11 was used to grab and discharge the cut debris to prevent the debris from settling at the bottom of the hole and affecting subsequent operations.

[0076] Step 8: The slag removal and tank wall trimming are carried out in conjunction with the 3rd tank forming machine;

[0077] The trenching machine 3 is positioned to the corresponding layered and segmented area, and slag is removed layer by layer in a manner adapted to the destructive layering, maintaining the mud parameters in the trench to ensure the stability of the borehole wall. After trenching, the flatness of the trench wall meets the requirements for diaphragm wall construction. Specifically, the entire trench section adopts a "top-down, layered and segmented, three-stage slag removal" process. The layering height is consistent with the previous obstacle removal layering height, and the length of a single segment is 4-6m. Each segment is divided into three positions: left, middle, and right, for sequential slag removal to ensure no blind spots in slag removal. First, the grab bucket is slowly lowered to the current layer. At the top, close the grab bucket and lower it vertically along the left side of the trench section to the bottom elevation of the layer. Slowly open the grab bucket to grab the debris from the bottom and walls of the trench. After closing the grab bucket, lift it smoothly out of the trench and unload the slag. Repeat the above process to complete the slag removal operation in the middle and right side of the trench section in sequence, ensuring that all sediment at the bottom of the trench is removed and all debris and loose soil attached to the walls are completely removed. After completing the slag removal of one layer, lower the grab bucket to the next layer and repeat the three-stage slag removal process until the designed bottom elevation of the trench section is reached.

[0078] Step 9: After the obstacle removal is completed, since the soil in the area affected by the obstacle has been removed along with the obstacle, there is no need to backfill or excavate again. Immediately replenish the trench with high-quality mud, restore the mud level to the control elevation of 30cm below the top surface of the guide wall, adjust the mud performance indicators to meet the requirements of subsequent construction, and immediately hand it over to the diaphragm wall construction team to complete the remaining trenching work.

[0079] Example 2:

[0080] This embodiment uses the construction of a diaphragm wall in a deep foundation pit of an urban expansion project as an application scenario. The stratum in the construction area is silty clay, and there is an obstacle that encroaches on the boundary line: a residual three-axis mixing pile water-stop curtain (encroaching on an area of ​​11.64m × 0.3m, with a burial depth of 20m) is cleared using the method of this invention. The specific process is as follows:

[0081] Step 1: General obstacle detection and parameterized data acquisition;

[0082] GPS positioning combined with total station verification was used to determine the coordinates of underground obstacle 1. Initial GPS positioning was performed, with the planar positioning error controlled within ±3cm. Then, the coordinates were verified using a total station, and the four corner points and central axis of obstacle 1 were laid out point by point. Simultaneously, the planar projection outline of obstacle 1 was marked on the top surface of the guide wall and the ground with spray paint, including the boundary line, center point, and the start and end range of the clearing operation. For deep obstacles with a burial depth exceeding 10m, a detection section was set every 1m along the axis of the diaphragm wall trench, with no fewer than 3 detection points on each section, forming a three-dimensional positioning grid in both planar and vertical directions. For shallow obstacles (burial depth ≤3m): excavators were used in conjunction with manual labor to remove the miscellaneous fill and plain fill covering the surface of obstacle 1 until the top surface of obstacle 1 was completely exposed. The width, length, and exposed height of obstacle 1 were manually measured with a measuring tape, and the material type was recorded. For deep obstacles (buried depth > 3m): First, a hydraulic trenching machine 3 is used to slowly grab the probe location, with the opening and closing range of the grab bucket controlled within 50cm and the single grab depth not exceeding 1m. The horizontal distribution boundary of obstacle 1 is determined by the grabbed debris sample. Then, a lightweight dynamic penetrometer is used to set up a probe point every 2m along the direction of obstacle 1 to determine the vertical burial depth and bottom elevation of obstacle 1. For high-strength walls such as concrete and reinforced concrete, small strain testing is additionally used to determine the strength, integrity, and internal reinforcement of obstacle 1. At the same time, clearing holes suitable for the wall thickness are extracted within the original obstacle area, with each hole tangent to the others.

[0083] Step 2: Standardized construction preparation and equipment adaptation;

[0084] One rotary drilling rig (2) and one hydraulic trenching machine (3) are selected. The rotary drilling rig (2) must meet the power requirements for drilling and breaking, with a main drive torque ≥400kNm. In this embodiment, a 420kN·m torque model is selected. The drilling rig must have real-time verticality monitoring, stepless speed regulation of the power head, and hydraulic correction function. After arrival on site, the power system, hydraulic system, and monitoring system must be debugged to ensure that all functions are normal. The hydraulic trenching machine (3) has a trenching efficiency ≥15m² / h, and the opening and closing stroke of the grab bucket matches the thickness of the diaphragm wall trench section. It has a real-time verticality monitoring function. After arrival on site, the wear of the grab bucket teeth must be checked. If the wear exceeds 10mm, it must be replaced in time to ensure that the grab bucket closes tightly.

[0085] Step 3: Mud wall protection;

[0086] Bentonite slurry was prepared in advance for use within the trench section. Before the obstacle removal operation, the prepared slurry was injected into the trench section, and the slurry level must be controlled to be no less than 30cm below the top surface of the guide wall. During the operation, slurry was continuously replenished simultaneously with the casing drilling, soil grabbing, and casing lifting to ensure that the slurry level remained stable within the controlled range. During the obstacle removal process, the slurry in the trench section, after settling with the excavated soil carried out by the grab bucket and drill bucket, flowed into the sedimentation tank. After being treated by the slurry purification equipment to remove sand, and the sand content was reduced to within the control value, it was pumped into the slurry pool for recycling. Waste slurry and excavated soil must be transported away in a timely manner.

[0087] Step 4: Casing installation and verticality control;

[0088] Installation of casing driver 4: First, rigidly connect the upper driver connection port 4a of casing driver 4 to the power head of rotary drilling rig 2 through a pin, ensuring that it is coaxial with the power head, and fully insert and lock the pin.

[0089] First section of casing installation: Position the first section of steel casing 6 with cutting edge, and make its top coaxial connection with the lower part of casing driver 4 through the first positioning groove and stop 4a. After the connection is completed, lock it with flange buckle to ensure that the steel casing 6 with cutting edge, casing driver 4 and power head are completely coaxial, with a coaxiality deviation of ≤2mm.

[0090] Verticality control: During construction, start the power head of the rotary drilling rig 2, and drive the steel casing 6 with cutting edge to rotate at a low speed through the casing driver 4. The speed is controlled at 5-8 r / min. At the same time, slowly apply downward pressure. The initial pressure is controlled within 30% of the rated pressure of the drilling rig (i.e., rotary drilling rig 2). Let the cutting edge of the steel casing 6 with cutting edge slowly cut into the soil layer. After the first section of the steel casing 6 with cutting edge penetrates the soil to a depth of ≥2m, the speed and pressure are gradually increased.

[0091] Casing extension: When the top surface of the first section of steel casing 6 with cutting edge is pressed down to 50cm from the top surface of the guide wall, stop rotating and pressing down, temporarily fix it to the orifice, disconnect the casing driver 4 from the steel casing 6 with cutting edge, hoist the next section of casing 8, and connect the two sections through the flange buckle at the second positioning groove and stop 8a. Tighten the bolts symmetrically and evenly, add sealing gaskets at the joint, and the joint gap ≤2mm. After the extension is completed, reconnect the casing driver 4 and continue the pressing and cutting operation. Repeat this process until the casing is close to the top surface of obstacle 1.

[0092] Step 5: Precisely destroy obstacle 1 in segments and layers;

[0093] Horizontal segmentation: Along the direction of the wall-shaped obstacle, the work section is divided according to the width of the trench formed by connecting the ground and the wall. The length of a single section is controlled between 4 and 6 meters. The obstacle 1 in a single trench section is divided at one time, and clear boundary marks are set between each section. For extra-long obstacles, the construction of skipped sections is adopted to avoid mutual disturbance between adjacent sections.

[0094] Vertical layering: Based on the geological features, the length of a single section of the casing, and the burial depth of obstacle 1, vertical layers are divided. The height of a single layer is controlled between 4 and 5 meters, and it is strictly prohibited for the height of a single layer to exceed 6 meters. The top and bottom elevations of obstacle 1 must be set up separately to ensure full coverage of obstacle 1.

[0095] On-site marking: On the top surface of the guide wall and around the trench section, use steel bar ends to mark the center point, hole boundary, and layer depth control line of each section of casing by spraying paint. The holes must be tangent to each other, and gaps that cause obstacles are strictly prohibited.

[0096] Layered obstacle removal and soil extraction and obstacle breaking construction: After the casing is pressed into place, disconnect the casing driver 4 from the casing, replace the corresponding drill bit, and carry out indiscriminate obstacle removal within the entire casing enclosure, removing obstacles inside the casing along with the original soil:

[0097] For high-strength obstacles such as concrete, masonry, and rock strata: Select a cylindrical drill 9 of the same diameter, first use the annular cutting teeth of the cylindrical drill 9 to cut the obstacle in a ring shape to form an annular free surface, then use a crushing drill bit to crush the obstacle in the core area, and finally use a sand scoop 11 to remove all the debris; the depth of a single cut should not exceed 30cm, and the rotation speed should be controlled at 5~8r / min to avoid overload and breakage of the cutting teeth.

[0098] For cohesive soil and silty soil: Use the body-opening drill 10, and control the drilling speed at 8~12 r / min. Utilize the opening and closing structure of the body-opening drill 10 to completely grab cohesive soil and soft obstacles, avoiding soil adhesion to the borehole wall and causing residue.

[0099] For miscellaneous fill and sandy soil layers: Select a sand scooping bucket 11, control the drilling speed at 10~15 r / min, and the single drilling depth should not exceed 50cm. After filling the drill bucket, slowly lift the drill bucket out of the hole, unload the slag, and repeat the operation until all soil and obstacles in the current layer are cleared.

[0100] Each drill bit connects its top drill body connector to the rotary drilling rig's power head via a pin. During the lifting and lowering of the drill bucket, the speed must be stable, with a lifting speed ≤10m / min. When approaching the bottom / mouth of the hole, the speed should be reduced to within 3m / min to avoid collision with the casing and causing it to float / sink.

[0101] When working inside the borehole, it is essential to ensure that the mud level remains stable. If soil removal causes the mud level to drop, mud must be replenished immediately. It is strictly forbidden for the mud level to fall below the control elevation.

[0102] If the rotary drilling rig 2 experiences severe shaking or abnormal noise when breaking high-strength obstacles, stop the operation immediately, lift the drill bit, check the wear of the drill bit, replace the damaged cutting teeth, and then continue construction. Overloading the equipment is strictly prohibited.

[0103] During the operation, a designated person will be assigned to observe the deformation of the surrounding soil and guide wall. If cracking or settlement occurs, the operation will be stopped immediately.

[0104] Step 6: Remove the casing

[0105] Release the casing lock: After clearing the obstacles and removing the soil, reconnect the rotary drilling rig 2 power head to the casing driver 4. The casing driver 4 is then locked to the top of the casing. Check the connection to ensure there is no risk of loosening or disengagement.

[0106] Borehole condition inspection: Use a measuring rope to verify the borehole depth and confirm that there are no large pieces of sediment or obstructions blocking the casing; check the mud performance indicators and liquid level in the borehole, and add mud to the control elevation to ensure that the wall protection effect meets the standard.

[0107] Lubrication preparation: High-quality bentonite slurry is injected through the grouting pipe into the gap between the outer wall of the casing and the soil to form a lubricating isolation layer and reduce the frictional resistance of the casing during lifting; the grouting volume is determined according to the burial depth of the casing, and the grouting volume of a single casing section is not less than 0.5m³.

[0108] Segmented lifting construction process:

[0109] Lifting principles: Strictly implement "segmented lifting, replenishment as you lift, and low-speed, stable lifting", and strictly prohibit lifting the entire length at once to avoid negative pressure collapse of the borehole wall.

[0110] Lifting operation: Start the rotary drilling rig's second power head to drive the casing to rotate alternately in the forward and reverse directions at a low speed of 3-5 r / min. At the same time, slowly apply the lifting force. The initial lifting force should be controlled within 1.2 times the casing's own weight. When the casing becomes loose and shifts upward, gradually increase the lifting force. The maximum lifting force must not exceed 70% of the drilling rig's rated lifting force. Overloading and forced lifting are strictly prohibited.

[0111] Segmented control: When the length of a single casing section is 4m, the single lifting height should be controlled within 3m. Pause the lifting, keep the casing rotating for 30s, inject lubricating mud again, and then continue lifting until the flange of the casing section protrudes 50cm from the orifice. Stop the lifting, temporarily fix the lower casing section to the orifice, remove the flange connecting bolts, completely pull out the casing section, and hoist it to the designated area. Repeat this process to remove all casing sections one by one.

[0112] Synchronous grouting control:

[0113] During the casing lifting process, a designated person should simultaneously replenish the hole with mud, ensuring that the mud replenishment speed is perfectly matched with the casing lifting speed. This will ensure that the mud level in the hole remains stable within 30cm below the top surface of the guide wall, and prevent any significant drop in mud level or the formation of negative pressure in the hole.

[0114] Casing Recycling and Inspection:

[0115] After the casing is removed, immediately clean the slag and cement lumps from the inner and outer walls of the casing. Check the roundness of the casing, the welds, the connecting clips, and the wear of the cutting edges. Repair any deformed or damaged parts. After repair, the casings should be classified and stored for recycling. Casings that cannot be repaired should be scrapped and must not be used again.

[0116] Step 7: Clear jagged corner obstacles;

[0117] Because serrated edges and corners remaining along the trench wall after the casing was cut and cleared, a segmented, layered drilling method using a tubular drill 9 was adopted. When the tubular drill 9 was difficult to remove, it was modified by welding a shovel 9a to one side of the tubular drill 9. The shovel plate 9a was made of 20mm thick steel plate and then cut and removed, ensuring that the cutting edge of the shovel plate 9a completely fits the serrated obstacles on both sides of the trench wall. The diameter of the drill bit is consistent with the design thickness of the diaphragm wall. The rotary drilling rig 2 drives the tubular drill 9 to rotate at a speed of 8~12r / min, cutting vertically along the trench wall in segments. The cutting height of a single operation does not exceed 2m. The lateral cutting force of the shovel plate 9a is used to completely scrape away and cut and break up the protruding serrated obstacles. After the cutting process, the debris is grabbed and discharged by the sand scoop 11 to prevent debris from settling at the bottom of the hole and affecting subsequent operations.

[0118] Step 8: The slag removal and tank wall trimming are carried out in conjunction with the 3rd tank forming machine;

[0119] The trenching machine 3 is positioned to the corresponding layered and segmented area, and slag is removed layer by layer in a manner adapted to the destructive layering, maintaining the mud parameters in the trench to ensure the stability of the borehole wall. After trench repair, the flatness of the trench wall meets the requirements for diaphragm wall construction. The entire trench section adopts a "top-down, layered and segmented, three-stage slag removal" method. The process involves cleaning layers at the same height as the previous clearing layers, with each section being 4-6 meters long. Each section is divided into three parts: left, middle, and right, for sequential cleaning to ensure no blind spots. First, the grab bucket is slowly lowered to the top of the current layer, then closed. It is then lowered vertically along the left side of the trench to the bottom elevation of the layer. The grab bucket is then slowly opened to grab debris from the bottom and walls of the trench. After closing the grab bucket, it is smoothly lifted out of the trench and the debris is unloaded. The above process is repeated to complete the cleaning of the middle and right sides of the trench, ensuring that all sediment at the bottom of the trench is removed and all debris and loose soil attached to the walls are completely removed. After cleaning one layer, the grab bucket is lowered to the next layer, and the three-stage cleaning process is repeated until the designed bottom elevation of the trench is reached.

[0120] Step 9: Process handover;

[0121] Once the obstacle removal work is completed and passes inspection, there is no need for backfilling or secondary excavation of the trench. High-quality mud should be immediately added to the trench, restoring the mud level to a control elevation 30cm below the top of the guide wall. The mud performance indicators should be adjusted to meet the requirements of subsequent construction. After handover, subsequent construction can commence, achieving a seamless transition between obstacle removal and subsequent work.

[0122] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A construction method for removing encroachment obstacles from the inner wall of a diaphragm wall, characterized in that, The process includes the following: Step 1: Obstacle (1) Location and parameter acquisition; Step 2: Construction preparation and equipment adaptation; Step 3: Mud wall protection; Step 4: The rotary drilling rig (2) drives the casing to press down and cut through the casing driver (4) until the casing approaches the top surface of the obstacle (1); Step 5: Divide the obstacle (1) into horizontal segments and vertical layers, disconnect the casing driver (4) from the casing, and use a rotary drilling rig (2) with different drill bits to carry out indiscriminate obstacle removal and soil extraction within the entire casing enclosure, removing the obstacle (1) inside the casing along with the original soil. Step 6: Remove the casing; Step 7: Clear jagged corner obstacles; Step 8: The tank forming machine (3) works in conjunction with slag removal and tank wall trimming; Step 9: Process handover.

2. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 1, characterized in that, In step 1, GPS positioning and total station verification are used to determine the coordinates of underground obstacles (1), and the planar projection outline of obstacles (1) is marked on the top surface of the guide wall and the ground. For shallow obstacles with a burial depth ≤ 3m, the surface covering of obstacles (1) is removed by excavator and manual labor, and the parameter information of obstacles (1) is measured manually. For deep obstacles with a burial depth > 3m, the trenching machine (3) is used to grab the probe position, and the horizontal distribution boundary of obstacles (1) is determined by the slag sample grabbed. The vertical burial depth and bottom elevation of obstacles (1) are determined by light dynamic penetrometer. For wall-type obstacles, the strength, integrity and internal reinforcement of obstacles (1) are determined by small strain detection. A parameterized database is established and the operation range is delineated.

3. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 1, characterized in that, In step 4, the casing is a segmented, extendable type, with the first segment being a steel casing (6) with a cutting edge, and the rest being ordinary casings (8); the specific process of step 4 includes: Connect the power head of the rotary drilling rig (2) to the casing driver (4), and then first connect the steel casing (6) with the cutting edge to the casing driver (4) coaxially. After the connection is completed, lock it with the flange to ensure that the steel casing (6) with the cutting edge, the casing driver (4) and the power head are coaxial. Start the power head of the rotary drilling rig (2) and drive the steel casing (6) with the cutting edge to rotate at a low speed through the casing driver (4). At the same time, slowly apply downward pressure and the steel casing (6) with the cutting edge cuts the stratum. When the steel casing (6) with the cutting edge is pressed down to 50cm from the top surface of the guide wall, When the rotation and pressing are stopped, the steel casing (6) with the cutting edge is temporarily fixed to the orifice. The connection between the casing driver (4) and the steel casing (6) with the cutting edge is released. The next ordinary casing (8) is hoisted and connected to the steel casing (6) with the cutting edge. A sealing gasket is installed at the joint. After the extension is completed, the casing driver (4) is reconnected and the pressing and cutting operation is continued. The above process is repeated until the casing is close to the top surface of the obstacle (1).

4. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 1, characterized in that, In step 5, horizontal segmentation: along the direction of the obstacle (1), the work section is divided according to the width of the trench formed by the ground wall, and the length of a single section is 4 to 6 m; the obstacle (1) in a single trench section is divided at one time, and a boundary marker is set between each section; for super long obstacles, the section skipping construction is adopted to avoid mutual disturbance between adjacent sections; vertical layering: according to the geological characteristics, the length of the single section of the casing, and the burial depth of the obstacle (1), the vertical layering is divided, and the height of a single layer is controlled within 4 to 5 m; the top and bottom elevation positions of the obstacle (1) are set separately to ensure that the obstacle (1) is fully covered.

5. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 1, characterized in that, In step 5, the corresponding drill bit is selected according to the strength of the obstacle (1) and the properties of the soil layer. For miscellaneous fill and sandy soil layers, the sand scoop (11) is selected. For cohesive soil and silty soil, the body drill (10) is selected. When clearing obstacles in harder rock layers, the obstacle is first cut by the ring-shaped cutting teeth of the barrel drill (9) to form a ring-shaped free surface. Then, the obstacle in the core area is broken by the crushing drill bit. Finally, the sand scoop (11) is used to remove all the debris. At the same time, when working in the hole, the mud level is kept stable. If the mud level drops due to soil removal, the mud is replenished immediately. It is strictly forbidden for the mud level to be lower than the control elevation.

6. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 1, characterized in that, Step 6 includes: After the soil removal in the hole is completed, the power head of the rotary drilling rig (2) is reconnected to the casing driver (4), and the casing driver (4) is connected to the top of the casing. Then, the hole depth is checked with a measuring rope to confirm that there are no large pieces of sediment or obstacles stuck in the casing. The mud performance index and liquid level in the hole are checked, and mud is added to the control elevation to ensure that the wall protection effect meets the standard. Bentonite mud is injected into the gap between the outer wall of the casing and the soil to form a lubricating isolation layer and reduce the frictional resistance of the casing lifting. Segmented lifting construction: Start the power head of the rotary drilling rig (2) to drive the casing to rotate alternately in the forward and reverse directions at low speed. At the same time, slowly apply the lifting force. The initial lifting force is controlled within 1.2 times the weight of the casing. When the casing becomes loose and moves upward, gradually increase the lifting force. The maximum lifting force shall not exceed 70% of the rated lifting force of the rotary drilling rig (2). The single lifting height shall be controlled within three-quarters of the length of a single casing section. Then stop the lifting, keep the casing rotating for a period of time, inject lubricating mud again, and then continue lifting until the flange of the casing section protrudes 50cm from the orifice. Stop the lifting, temporarily fix the lower casing to the orifice, remove the flange connecting bolts, completely pull out the casing section and hoist it to the designated area. Repeat this process to remove all casing sections one by one.

7. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 6, characterized in that, During the casing extraction process, a designated person simultaneously replenishes mud into the hole, with the mud replenishment speed perfectly matched to the casing extraction speed, ensuring that the mud level in the hole remains stable within 30cm below the top surface of the guide wall. After the casing is pulled out, the slag and cement lumps on the inner and outer walls of the casing are immediately cleaned. The roundness of the casing, welds, connecting clips, and wear of the cutting edges are checked. Deformed or damaged parts are repaired. Casings that pass the repair are classified and stored for recycling. Casings that cannot be repaired are scrapped.

8. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 1, characterized in that, Step 7 includes: After the casing is cut and cleared, the serrated corner obstacles left along the trench wall are still not cleared. The casing drill (9) is used to cut in sections and layers. When the casing drill (9) is difficult to clear, it is modified. A shovel plate (9a) is welded on one side of the casing drill (9). The shovel plate (9a) is made of 20mm thick steel plate. Then, it is cut and cleared to ensure that the cutting edge of the shovel plate (9a) is completely in contact with the serrated obstacles on both sides of the trench wall. The rotary drilling rig (2) drives the casing drill (9) to rotate and cut vertically along the trench wall in sections. The height of a single cut does not exceed 2m. The lateral cutting force of the shovel plate (9a) is used to completely scrape off and cut the protruding serrated obstacles. After cutting, the debris is picked up and discharged by the sand scoop (11).

9. The construction method for removing encroachment obstacles from the inner wall of a diaphragm wall according to claim 1, characterized in that, Step 8 includes: The trenching machine (3) is positioned in the corresponding layered and segmented area. The "top-down, layered and segmented, three-stage slag removal" process is adopted. The layering height is consistent with the layering height of the previous obstacle removal. Each segment is divided into three positions: left, middle and right, and slag is removed in sequence until the bottom elevation of the trench section is designed. At the same time, the mud parameters in the trench are maintained to ensure the stability of the hole wall. After the trench is repaired, the flatness of the trench wall meets the requirements of the diaphragm wall construction.

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