External wall brushing device and trenching method for ultra-deep underground continuous walls in highly permeable strata

Abstract

This invention relates to an external wall-mounted scrubbing device and a method for trenching ultra-deep diaphragm walls in highly permeable strata. The external wall-mounted scrubbing device is fixed to the outside of a grab bucket via upper and lower fixings, and consists of a scraper fixing plate, a brush plate, and a fixing plate arranged sequentially from top to bottom. The method includes the following steps: constructing a guide wall, surveying the rock surface to determine the design depth of each unit trench segment; excavating the unit trench segment using a three-grip method; and installing the external wall-mounted scrubbing device on both sides of the grab bucket to clean the wall surface. The advantages of this invention are: using the three-grip method to excavate the unit trench segment ensures balanced force on the grab bucket; accurately determining the on-site diaphragm wall construction depth avoids wasted effort caused by uniform depth design, further improving construction efficiency; and designing an external wall-mounted scrubbing device that can be installed on one or both sides of the grab bucket allows for both standalone scrubbing and simultaneous use during trenching.

Description

Technical Field

[0001] This invention belongs to the field of continuous wall construction technology, and particularly relates to an external wall brushing device and a method for trenching ultra-deep underground continuous walls in highly permeable strata. Background Technology

[0002] With the development of urbanization and the increasing convenience of rail transit, considering factors such as foundation pit safety and water-stopping effect, diaphragm walls, as a form of enclosure with less foundation pit deformation and better water-stopping effect, are being applied to more and more projects.

[0003] In current urban planning, riverside and waterfront areas are becoming the new development centers of cities, experiencing continuous and intensified development. Furthermore, due to increasingly sophisticated groundwater protection measures, these areas generally have high groundwater content and stable water levels. To ensure the safety of the foundation pit, the design of diaphragm walls requires a simple structure and the addition of barriers to confined water. This means that the design depth of the diaphragm walls will extend below the bedrock, making it difficult for traditional trenching machines to meet the construction schedule and safety requirements of the trench sections.

[0004] Traditional trenching operations utilize machinery such as trenching machines and trenching machines. Trenching machines use hydraulic grabs to create trenches, offering low cost and fast construction speed, but they are ineffective in handling hard rock formations. Therefore, when dealing with hard rock, the grab must employ an impact method, causing significant disturbance to the trench section and nearby underground facilities. While trenching machines are highly effective in handling hard underground rock formations, they are costly, inefficient, and unsuitable for clay loam, boulders, or large pebbles. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an external wall brushing device and a method for trenching ultra-deep underground continuous walls in highly permeable strata.

[0006] This external wall brush is mounted on the outside of the grab bucket via upper and lower fixings. Several holes are provided on both the upper and lower fixings along the horizontal direction to adjust the extension length of the external wall brush. From top to bottom, the external wall brush consists of a scraper fixing plate, a brush plate, and a fixing plate.

[0007] A soft scraper is sandwiched between two scraper fixing plates. The front end of the brush plate is provided with a brush plate end. Several scraper rods are fixed to the front end of the fixing plate, and each scraper rod is individually fixed by a fixing bolt. The extension length of the soft scraper, the brush plate end, and the front end of the scraper rods decreases in sequence, and the rigidity increases in sequence.

[0008] Preferably, the two scraper fixing plates are arranged vertically and vertically, and the opposite surfaces are provided with mutually cooperating scraper fixing grooves. The soft scraper is inserted into the gap between the two scraper fixing plates and has a corresponding bend at the scraper fixing groove. There is also a scraper fixing bolt that passes through the two scraper fixing plates and the soft scraper.

[0009] Preferably, a reinforcing structure is provided between the brush plate and the main body of the external wall brush, the cross-section of the brush plate end is triangular, and the front end of the brush plate end is provided with a brush head, which is arc-shaped.

[0010] Preferably, several scrapers are spaced horizontally at the front end of the fixed plate, and the part of each scraper inserted into the fixed plate is fixed by fixing bolts.

[0011] The method for trenching ultra-deep underground continuous walls in highly permeable strata using this external wall-mounted brushing device includes the following steps:

[0012] Step 1: Construct the guide wall. Divide the underground continuous wall into several unit sections, with the length of each unit section being less than or equal to three times the width of the grab bucket. Explorate the rock surface to determine the design depth of each unit section.

[0013] Step 2: Use the three-grab method to excavate the unit trench segment, divide the unit trench segment into three sections along the length direction, and excavate, drill holes and clean the bottom of the two side sections in sequence, so that the central section of the unit trench segment forms a partition wall, the length of which is less than the width of the grab bucket.

[0014] Step 3: Install the external wall brush on both sides of the grab bucket. Adjust the upper and lower fixing holes according to the width of the unit slot. Excavate the partition wall. As the grab bucket opens and moves downward, the scraper, brush plate end and soft scraper will clean the wall surface in sequence.

[0015] Step 4: After the partition wall is excavated to the rock strata, pilot holes are drilled and the bottom is cleaned to complete the trenching construction of the unit trench section.

[0016] Preferably, in step two, the excavation, pilot hole drilling, and bottom cleaning of both sides of the trench are carried out alternately. After the first side section is excavated to the rock surface, the second side section is excavated, and at the same time, a rotary drilling rig is used to drill holes in the rock surface of the first side section. Then, the bottom of the first side section is cleaned, and at the same time, a rotary drilling rig is used to drill holes in the rock surface of the second side section. Finally, the bottom of the second side section is cleaned.

[0017] As a preferred method, after completing the excavation, drilling, and bottom cleaning of the partition wall, an external wall brush is installed on one or both sides of the grab bucket to clean the wall surface.

[0018] As a preferred option, when the scraper is damaged, the corresponding fixing bolts can be removed and the damaged scraper replaced.

[0019] The beneficial effects of this invention are:

[0020] 1) This invention uses a three-grab method to excavate unit trench sections. During the third grab, the grab bucket can directly enclose the partition wall for excavation, making the grab bucket exert force evenly, effectively correcting deviation, ensuring the verticality of the trench, and effectively avoiding the underground continuous wall trench section being exposed for too long, resulting in adverse phenomena such as hole collapse and diameter reduction after hole formation, and the risk is controllable.

[0021] 2) After reaching the rock strata, a rotary drilling rig is used to break the rock through pre-drilling. Utilizing the significant decrease in overall rock hardness after breakage, the trenching machine can continue its gripping operations, avoiding equipment damage and low efficiency issues caused by drilling and gripping. The operation is simple and requires minimal site conditions. The initial trenching with a trenching machine is fast and produces good verticality, while the subsequent pre-drilling with a rotary drilling rig minimizes disturbance and speed. The requirements for auxiliary facilities are low, thus accelerating trenching speed while ensuring trenching quality.

[0022] 3) By using the "one wall, one survey" in-situ construction survey technology, the actual construction depth of the underground continuous wall on site can be determined, avoiding the waste of work efficiency caused by uniform depth design and further improving construction efficiency.

[0023] 4) An external wall brusher that can be installed on one or both sides of the grab bucket was designed. It can be used alone for wall brushing construction or simultaneously during trenching. From bottom to top, it is equipped with scraper rods, brush plates and soft scraper strips. The rigidity of the scraper is progressively increased, which can achieve the effect of cleaning the trench wall in a step-by-step manner. Each scraper rod is fixed by a fixing bolt and can be disassembled and replaced individually, which improves the utilization rate. Attached Figure Description

[0024] Figure 1 This is a structural diagram of an external wall brush.

[0025] Figure 2 This is a picture of the back of an external wall brush.

[0026] Figure 3 This is a diagram showing the construction sequence of the trench;

[0027] Figure 4 This is a flowchart of the trenching method for ultra-deep underground continuous walls in highly permeable strata.

[0028] Explanation of reference numerals in the attached drawings: 1. Scraper fixing plate; 2. Scraper fixing bolt; 3. Scraper fixing groove; 4. Soft scraper; 5. Reinforcing structure; 6. Brush plate end; 7. Brush plate head; 8. Fixing plate; 9. Plate fixing bolt; 10. Scraper rod; 11. Upper fixing; 12. Lower fixing. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0030] Example 1

[0031] As one example, such as Figure 1 and Figure 2 As shown, an external wall brush is provided. On the outward-facing side of the external wall brush, from top to bottom, there is a scraper fixing plate 1, a brush plate, and a fixing plate 8.

[0032] A soft scraper 4 is sandwiched between two scraper fixing plates 1. The two scraper fixing plates 1 are arranged vertically, and their opposite surfaces have mutually cooperating scraper fixing grooves 3. The soft scraper 4 is inserted into the gap between the two scraper fixing plates 1, and has a corresponding bend at the scraper fixing groove 3. There is also a scraper fixing bolt 2 that penetrates through the two scraper fixing plates 1 and the soft scraper 4. The scraper fixing groove 3 is tightly engaged with the soft scraper 4, and the setting of the scraper fixing groove 3 can increase the stability of the soft scraper 4.

[0033] The front end of the brush plate is provided with a brush plate end head 6, and a reinforcing structure 5 is provided between the brush plate and the main body of the external wall brush. The cross-section of the brush plate end head 6 is triangular, and the front end of the brush plate end head 6 is provided with a brush plate head 7, which is arc-shaped.

[0034] Several scraper rods 10 are fixed to the front end of the fixed plate 8. The scraper rods 10 are spaced horizontally at the front end of the fixed plate 8, and the part of each scraper rod 10 inserted into the fixed plate 8 is fixed by a fixing bolt 9.

[0035] The lengths of the soft scraper 4, the brush plate end 6, and the front end of the scraper 10 decrease sequentially, while their rigidity increases sequentially. In this embodiment, nine scraper rods 10 are evenly arranged at the bottom of the external wall brush. The scraper rods 10 are easy to replace and can be replaced individually, allowing for initial treatment of large protrusions and defects.

[0036] The brush is mainly used to scrape away soil and rock from the surface of the diaphragm wall. The arc structure of the brush head 7 can reduce the resistance between the brush end 6 and the diaphragm wall, making it easier for the brush end 6 to scrape away soil while making the diaphragm wall smoother. This avoids damage to the brush end 6 and extends its service life.

[0037] The soft scraper 4 is mainly used to initially remove the soil remaining after the scraper treatment and to treat the fine soil particles.

[0038] Example 2

[0039] As another embodiment, such as Figure 2 As shown, the external wall brusher described in Embodiment 1 is installed on the outside of the grab bucket via an upper fixing 11 and a lower fixing 12. The external wall brusher can be installed according to the actual site conditions. It can be installed on one side alone for single-sided wall brushing operations on the ground-connected wall, or it can be installed on both sides for double-sided wall brushing operations.

[0040] The upper fixing 11 and the lower fixing 12 are provided with two sets. The upper fixing 11 and the lower fixing 12 are provided with several holes in the horizontal direction to form an adjustable length connecting component, so as to fix it with the trenching machine bucket and to adjust the extension length of the external wall brush.

[0041] In actual field use, construction personnel adjust the back connection mechanism according to different trench types to ensure the matching degree of on-site construction, which can meet the connection and use of most trenching machines.

[0042] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

[0043] Example 3

[0044] As another embodiment, this embodiment three proposes a method for trenching ultra-deep underground continuous walls in highly permeable strata using the external wall-mounted brushing device described in embodiments one and two, such as... Figure 3 and Figure 4 As shown, it includes the following steps:

[0045] Step 1: Construction of the guide wall. The specific process includes site leveling, measurement and positioning, trenching and disposal of excavated soil, subbase layer, reinforcement binding, formwork erection, concrete pouring, formwork removal and installation of horizontal bracing.

[0046] The guide wall is primarily excavated using excavators, supplemented by manual excavation, and constructed in sections, each approximately 30–50 meters long. The specific section length is determined based on the actual site conditions. The construction joints of the guide wall are staggered from the section joints of the diaphragm wall by at least 0.5 meters.

[0047] Considering that the construction equipment needs to be switched during the construction of this method, the construction quality of the guide wall is required to be high. Otherwise, road surface collapse and shallow soil collapse may occur. Before the construction of the guide wall and the adjacent heavy-duty road, the base soil layer is replaced, ballast is laid, and the reinforcement and concrete grade are appropriately increased. If necessary, steel plates are laid near the trench section during the construction process to avoid adverse effects on the trench section caused by the operation of the machinery.

[0048] After the guide wall construction is completed, the underground continuous wall is divided into several unit sections, with each section having a length less than or equal to three times the width of the grab bucket.

[0049] The design depth of the diaphragm wall mainly depends on the requirements of the foundation pit retaining structure and the need to isolate confined water. The wall must penetrate at least 1.5m into the strongly weathered rock layer to ensure confined water isolation. Considering various factors such as the undulating rock surface and the distribution of exploration points, a uniform wall elevation will inevitably result in insufficient penetration depth in some areas, failing to adequately meet water isolation requirements; while excessive penetration depth in other areas will lead to wasted on-site work efficiency. Therefore, an in-situ construction exploration approach of "one wall, one exploration" is adopted to investigate the rock surface, determine the design depth of each unit section, and construct accordingly.

[0050] Step 2: Taking into account the construction efficiency of the trenching machine, the underground continuous wall is divided into unit trenches with a width of about 6m. In this embodiment, the grab bucket of the trenching machine is 2.8m wide. The three-grab method of first digging on both sides and then digging in the middle is used to excavate the unit trenches. Alternatively, after digging the first hole, a certain distance is skipped before digging the second hole, so that an unexcavated partition wall is left between the two single holes.

[0051] like Figure 3 As shown, the unit trench section is divided into three segments along its length. Excavation, pilot drilling, and bottom cleaning of both side segments are carried out sequentially, alternating between the two side segments. After excavating the first side segment to the rock surface, the second side segment is excavated, while simultaneously pilot drilling is performed on the rock surface of the first side segment using a rotary drilling rig. Then, the bottom of the first side segment is cleaned, while pilot drilling is performed on the rock surface of the second side segment using a rotary drilling rig. Finally, the bottom of the second side segment is cleaned, forming a partition wall in the central section of the unit trench section. The length of the partition wall is less than the width of the grab bucket. This construction sequence reduces the exposure time of large-area trench segments; for most of the time, the exposed width of the trench segment is approximately 2.8m, making the risk relatively controllable.

[0052] Step 3: Excavate the partition wall. The length of the partition wall is less than the opening length of the grab bucket, allowing the grab bucket to fit over the partition wall for excavation. This ensures even force distribution on the grab bucket, effectively correcting deviations and guaranteeing the verticality of the trench. This allows the grab bucket to distribute force evenly when excavating a single hole, effectively correcting deviations and ensuring the verticality of the trench.

[0053] Step 4: After excavating the partition wall to the rock strata, pre-drilling and bottom cleaning are carried out. Once both the single holes and the partition walls have been excavated to the designed depth, several more excavations are performed along the length of the trench. This process smooths out any uneven surfaces caused by the varying verticality of the grab bucket during the excavation of the single holes and partition walls, ensuring good straightness of the trench section laterally. After completing the trenching of the unit section and allowing it to stand for half an hour, a hydraulic grab bucket is used to simultaneously excavate along the length of the trench while lowering the grab bucket to the designed depth to remove the sediment at the bottom of the trench.

[0054] When the scraper 10 is damaged, remove the corresponding fixing bolt 9 and replace the damaged scraper 10.

[0055] Example 4

[0056] As another embodiment, this fourth embodiment proposes a brushing method for trenching in ultra-deep underground continuous walls in highly permeable strata, based on the third embodiment:

[0057] Adjust the hole positions of the upper fixing 11 and lower fixing 12 according to the width of the unit slot, install the external wall brush on both sides or one side of the grab bucket, and then excavate the partition wall. During the process of the grab bucket opening and moving downward, the scraper 10, the brush plate end 6 and the soft scraper 4 clean the wall surface in sequence. Alternatively, the wall brushing can be carried out without excavating the partition wall, but after the partition wall excavation, pilot hole and bottom cleaning are completed, the external wall brush is installed on one or both sides of the grab bucket to clean the wall surface.

[0058] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 3 can be referred to each other, and will not be repeated in this application.

[0059] Example 5

[0060] As another embodiment, this fifth embodiment proposes a rotary drilling rig pre-drilling method for trenching ultra-deep underground continuous walls in highly permeable strata, based on the fourth embodiment:

[0061] While trenching machines offer high efficiency and minimal disturbance when working on non-rocky soil layers, their hydraulic grab buckets are ineffective at gripping the underlying rock, resulting in extremely low efficiency, prolonged trench exposure, and a significantly increased risk of borehole collapse. To facilitate trenching, three pilot holes are used for each continuous wall trench section. After each grab, a rotary drilling rig is used to drill pilot holes at the corresponding location, with the depth extending from the strongly weathered rock surface to 1.5 meters into the strongly weathered rock layer. The mud slurry density should be increased during pilot hole drilling to prevent borehole collapse. Research has shown that the low efficiency of trenching machines on mudstone surfaces is significantly improved after using a rotary drilling rig for pilot hole drilling on the mudstone surface. Each grab can save 7 to 8 hours of construction time.

[0062] In this embodiment, the allowable ranges for various deviations after grooving are shown in the table below:

[0063]

[0064] The construction of ultra-deep diaphragm walls employs a mud slurry method to ensure trench wall stability during trenching operations. The quality of the mud slurry directly affects trench wall stability and requires strict control. Trenching is divided into two phases: trench preparation and pilot hole preparation, using mud slurries of different specific gravities. The mud slurry performance requirements are shown in the table below:

[0065]

[0066] To ensure the project schedule and mud quality, the mud must be prepared at least 24 hours in advance and allowed to stand for 24 hours before acceptance testing. Only after passing the acceptance test can the mud be put into use. During trenching, record the soil sample type every 1.5 meters of advance and check the parameters of the circulating mud at the bottom of the trench every 5 meters of advance. Record the results. If any problems are found, stop the excavation immediately and adjust the mud parameters.

[0067] It should be noted that the parts in this embodiment that are the same as or similar to those in embodiments three and four can be referred to each other, and will not be repeated in this application.

[0068] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

Claims

1. A method for trenching a super deep underground continuous wall in a highly permeable stratum, using an externally mounted wall brushing device, characterized in that: The device is installed on the outside of the grab bucket through the upper fixing (11) and the lower fixing (12), the upper fixing (11) and the lower fixing (12) are respectively provided with a plurality of hole positions in the horizontal direction for adjusting the length of the externally-hung wall brushing device; the externally-hung wall brushing device is sequentially provided with a scraping strip fixing plate (1), a brushing plate and a fixing plate (8) from top to bottom, The soft scraping strip (4) is clamped between the two scraping strip fixing plates (1), the brushing plate front end is provided with a brushing plate end head (6), the fixing plate (8) front end is fixed with a plurality of scraping rods (10), each scraping rod (10) is fixed by a fixing bolt (9) alone; the soft scraping strip (4), the brushing plate end head (6) and the scraping rod (10) front end stretch out in length in turn, and the rigidity increases in turn; the brushing plate and the externally-hung wall brushing device main body are provided with a reinforcing structure (5), the brushing plate end head (6) cross section is triangular, the brushing plate end head (6) front end is provided with a brushing plate head (7), the brushing plate head (7) is arc-shaped; The method comprises the following steps: Step one, construction guide wall, divide the underground continuous wall into a plurality of unit groove sections as a unit of each wall, the length of each unit groove section is less than or equal to three times the width of the grab bucket, survey the rock surface to determine the design depth of each unit groove section; Step two, adopt three-grab method to excavate the unit groove section, divide the unit groove section into three sections along the length direction, excavate the two side sections in turn, hole drilling and bottom cleaning, so that the central section of the unit groove section forms a partition wall, the length of the partition wall is less than the width of the grab bucket; the excavation, hole drilling and bottom cleaning of the two side sections of the groove section are alternately carried out, after the excavation of the first side section to the rock surface, the excavation of the second side section is carried out, and at the same time, the rock surface of the first side section is hole drilled by the rotary excavator; then the bottom of the first side section is cleaned, and at the same time, the rock surface of the second side section is hole drilled by the rotary excavator; finally, the bottom of the second side section is cleaned; Step three, install the externally-hung wall brushing device on the two sides of the grab bucket, adjust the hole positions of the upper fixing (11) and the lower fixing (12) according to the width of the unit groove section, excavate the partition wall, and the scraping rod (10), the brushing plate end head (6) and the soft scraping strip (4) clean the wall surface in turn during the process of opening and moving downward of the grab bucket; Step four, after the partition wall is excavated to the rock layer, hole drilling and bottom cleaning are carried out, and the trenching construction of the unit groove section is completed.

2. The method of claim 1, wherein the method is characterized by: The two scraping strip fixing plates (1) are arranged in the up-down direction, and the opposite surfaces are provided with scraping strip fixing grooves (3) matched with each other, the soft scraping strip (4) is inserted into the gap between the two scraping strip fixing plates (1), and corresponding bending is arranged at the scraping strip fixing grooves (3), and the scraping strip fixing bolt (2) penetrates through the two scraping strip fixing plates (1) and the soft scraping strip (4).

3. The method of claim 1, wherein the method is characterized by, The plurality of scraping rods (10) are arranged at the front end of the fixing plate (8) in the horizontal direction, and the part of each scraping rod (10) inserted into the fixing plate (8) is fixed by the fixing bolt (9).

4. The method of claim 1, wherein the method is characterized by, After the partition wall excavation, hole drilling and bottom cleaning are completed, the externally-hung wall brushing device is installed on one side or both sides of the grab bucket to clean the wall surface.

5. The method of claim 1, wherein the method further comprises: When the scraping rod (10) is damaged, the corresponding fixing bolt (9) is removed to replace the damaged scraping rod (10).

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