Caisson cutting edge structure, intelligent control system for caisson sinking and construction methods

Abstract

This invention discloses a caisson cutting edge structure, a caisson sinking intelligent control system, and a corresponding construction method. The caisson cutting edge structure includes a cutting edge fan ring section with and without a mud sleeve, which are alternately welded in the circumferential direction to form the caisson cutting edge structure. The radial outer ring of the cutting edge fan ring section without a mud sleeve is flush with the outer surface of the caisson wall. The radial outer ring of the cutting edge fan ring section with a mud sleeve is an upward-opening mud collection trough, the radial outer wall of which protrudes from the outer surface of the caisson wall. The caisson wall corresponding to the cutting edge fan ring section without a mud sleeve plays a role in positioning, guiding, and preventing deviation of the caisson. Different pressures are applied to different parts of the mud sleeve to correct the caisson's deviation. Grouting does not impact the sand and gravel strata, which is beneficial for the rapid formation of the mud lubrication layer and prevents a large amount of mud from entering the sand and gravel strata and polluting the groundwater.

Description

Technical Field

[0001] This invention relates to the field of caisson engineering technology, and in particular to an intelligent control system and construction method for caisson sinking. Background Technology

[0002] A caisson is a cylindrical structure. During the sinking process, the resistance to sinking generally consists of the reaction force of the foundation at the bottom and the frictional resistance between the caisson wall and the soil. When the caisson sinks to a greater depth, the lateral frictional resistance may become a significant factor hindering the smooth sinking of the caisson.

[0003] Gravel and sand formations are typical mechanically unstable formations, characterized by loose structure, high porosity, strong permeability, and low cohesion. When constructing caissons under gravel and sand geological conditions, the presence of side friction causes the surrounding soil to sink during the caisson's descent, leading to soil subsidence and increased friction between the caisson wall and the soil. This can easily result in slow caisson descent or even failure to sink at all.

[0004] In the geological conditions of sandy and gravelly strata with high groundwater levels, when using the non-drainage sinking (underwater excavation) method for sinking operations, the technical difficulty is that tilting is prone to occur during the sinking process, and correction is relatively difficult. When using the drainage sinking (draining groundwater and then excavating) method for sinking operations, dewatering and the addition of water-stopping curtains such as cement mixing piles are required, which results in a long construction period and high costs.

[0005] Currently, the main sinking aids employed include air curtains, water curtains, and mud sleeves. However, in water-rich sandy and gravelly strata, air curtains and water curtains may cause soil collapse, resulting in blockage of the well wall and slow or even no sinking of the caisson. When using mud sleeves, the slurry outlet directly impacts the soil, easily causing mud loss, resulting in poor sinking effectiveness and potential groundwater pollution. Specifically, mud sleeve sinking involves making the outer diameter of the caisson's cutting edge slightly larger than the outer diameter of the main caisson wall. This creates an annular gap between the caisson's outer wall and the soil (sandy and gravelly strata) during sinking. Grouting is injected into this gap to form a mud sleeve, significantly reducing the friction between the caisson's sidewall and the soil. Due to the loose nature of the sand and gravel strata, when the grouting slurry in the grouting pipe impacts the sand and gravel strata, it is easy for the slurry to enter the sand and gravel strata. On the one hand, it is not easy to form a slurry jacket (forming a slurry jacket requires a much larger amount of slurry than ordinary strata). On the other hand, a large amount of slurry entering the sand and gravel strata pollutes groundwater resources.

[0006] The horizontal and vertical displacements of the caisson structure are the main control parameters for caisson construction. Current monitoring methods require multiple operators, are prone to overcorrection, and can lead to human error.

[0007] The problems in the existing technology mainly arise in well-sinking operations in sandy and gravelly geological conditions with high groundwater levels. The overall research and development objective of this invention is to address the issue of successful well-sinking in water-rich sandy and gravelly geological conditions with high groundwater levels. Specifically, it aims to solve the problems of resistance reduction and deviation correction during the well-sinking process, while also resolving the issues of poor sinking effect and groundwater pollution caused by the direct impact of the slurry outlet on the sandy and gravelly strata. Summary of the Invention

[0008] The problem this invention aims to solve is to provide a caisson cutting edge structure for geological conditions with high groundwater levels and gravel strata. This structure facilitates the formation of a lubricating mud layer and allows for the formation of a positioning guide section that is evenly spaced around the perimeter, directly contacting the gravel strata with the caisson wall. It also prevents the mud outlet from directly impacting the gravel strata, which could lead to poor settling effect and groundwater pollution.

[0009] To achieve the above objectives, the present invention provides a caisson cutting edge structure for use in caissons, connected to the lower end of the caisson wall, comprising a radial outer ring wall, a radial inner ring wall, and a bottom wall connecting the bottom ends of the radial outer ring wall and the radial inner ring wall, wherein the radial inner ring wall is in the shape of a trumpet, which is smaller at the top and larger at the bottom.

[0010] It includes a mud-jacketed cutting edge fan ring section and a mud-jacket-less cutting edge fan ring section. The mud-jacketed and mud-jacket-less cutting edge fan ring sections are alternately welded in the circumferential direction to form the caisson cutting edge structure.

[0011] Both the mud-jacketed and mud-free cutting edge fan ring segments include a radial outer ring segment, a radial inner ring segment, and a bottom fan ring segment connecting the bottom walls of the radial outer ring segment and the radial inner ring segment; each radial outer ring segment is welded to form a radial outer ring wall, each radial inner ring segment is welded to form a radial inner ring wall, and each bottom fan ring segment is welded to form a bottom wall.

[0012] The outer surface of the radial outer ring of the mud-free blade foot fan ring is flush with the outer surface of the well wall of the caisson;

[0013] The radial outer ring of the mud-jacketed foot fan ring section is an upward-opening mud collection trough, and the radial outer wall of the mud collection trough protrudes from the outer surface of the well wall.

[0014] The sum of the circumferential lengths of the radial inner ring segments of each of the mud-sleeve cutting edge fan ring segments is L1.

[0015] The sum of the circumferential lengths of the radial inner ring segments of each mud-free blade fan ring segment is L2;

[0016] L1:L2≥4:1; Each mud collection groove with mud sleeve cutting edge fan ring section is provided with grouting holes on its radial inner surface. The grouting holes are used to connect with the grouting pipes pre-embedded in the caisson wall; the mud sleeve cutting edge fan ring section is provided with 3 to 5 holes.

[0017] An eaves plate extends outward from the top of the radial inner wall of the mud collection trough, and the outer diameter of the eaves plate is the same as the outer diameter of the well wall of the caisson; the eaves plate and the top of the radial outer wall of the mud collection trough form a mud outlet.

[0018] The present invention also provides an intelligent control system for sinking a caisson. The caisson includes a caisson wall, and the lower end of the caisson wall is connected to the caisson cutting edge structure. There are four cutting edge fan ring sections with mud sleeves and four cutting edge fan ring sections without mud sleeves.

[0019] Includes grouting mechanism, sensing mechanism and electrical control device;

[0020] The grouting mechanism includes grouting pipes pre-embedded in the well wall of the caisson, with four grouting pipes corresponding one-to-one with the mud-sleeved cutting edge fan ring section;

[0021] The bottom end of the grouting pipe is connected to the grouting hole of the corresponding mud-sheathed blade fan ring section and is used to grout into the corresponding mud collection tank.

[0022] The top of the grouting pipe extends out of the well wall and is connected to the outlet pipe of the grouting pump located on the ground. The inlet pipe of the grouting pump is connected to the grout container. A pressure regulating solenoid valve is connected in series at the top of each grouting pipe.

[0023] Sensor wiring slots are pre-embedded at the bottom of the inner wall of the caisson, with the east, southeast, south, southwest, west, northwest, north, and northeast directions referred to as the eight directions; four sensor wiring slots are provided for any four adjacent directions of the eight directions of the caisson.

[0024] The sensor mechanism includes a pressure sensor, four tilt sensors, sensor wiring slots, and conduits. Each sensor wiring slot contains a set of tilt sensors. There is one pressure sensor located in any one of the sensor wiring slots. A pressure measuring tube is connected between the mud outlet and the pressure sensor. The pressure measuring tube is used by the pressure sensor to monitor the mud pressure at the mud outlet.

[0025] Four conduits are pre-embedded in the wall of the caisson. Each conduit is connected to a corresponding sensor wiring slot. The upper end of each conduit extends out of the top of the caisson wall. The lines of the pressure sensor and tilt sensor pass through the corresponding conduits to the ground and are connected to the electrical control device.

[0026] The electrical control device is located on the ground and connected to a display screen. The electrical control device is connected to the grouting pump, pressure regulating solenoid valve, pressure sensor and tilt sensor.

[0027] The electronic control device has a housing with eight indicator lights along its circumference, which correspond to and are used to indicate the eight directions: east, southeast, south, southwest, west, northwest, north, and northeast.

[0028] During the sinking process, when the caisson tilts, one side of the caisson becomes the raised end and the opposite side becomes the sunken end; the electrical control device controls the indicator light in the direction corresponding to the raised end of the caisson to light up.

[0029] This invention also provides a construction method for the above-mentioned intelligent control system for caisson sinking, used for caisson construction in sandy and gravelly geological conditions with high groundwater levels, and is carried out according to the following steps:

[0030] The first step is to preset the parameters;

[0031] The grouting pressure of the grouting pump is set to P1. The pressure sensor reading P increases with the sinking depth of the caisson. During construction, the electrical control device determines the latest grouting pressure P1 in real time based on the pressure sensor reading P. P1 = R × P, where R is a dimensionless parameter and its specific value is determined by the staff. Its value range is 1.1 ≤ R ≤ 1.5.

[0032] The initial opening degree of each pressure regulating solenoid valve is 50%. When the well wall of the caisson is exactly vertical, the reading of each tilt sensor is 0. The angle between the well wall of the caisson and the vertical plane is α. When -0.1 degrees ≤ α ≤ 0.1 degrees, no tilt adjustment action is performed; otherwise, tilt adjustment action is performed.

[0033] The rules for the 8 indicator lights to turn on and off are as follows:

[0034] When the measured value β of the tilt sensor corresponding to a mud-sleeve cutting edge fan ring section deviates from the vertical by more than ±0.1 degrees, the electronic control device determines whether the tilt sensor is located at the raised end or the sunken end of the caisson based on the positive and negative characteristics of β. If the tilt sensor is located at the sunken end of the caisson, then the part of the caisson directly opposite the tilt sensor is the raised end of the caisson; the electronic control device controls the indicator light corresponding to the raised end of the caisson to light up.

[0035] When two tilt sensors are both located at the raised end of the caisson, the electronic control device will control the indicator lights corresponding to the locations of the two tilt sensors to light up simultaneously; if there are indicator lights between the two lit indicator lights, the indicator lights between the two lit indicator lights will also light up.

[0036] The second step is to construct the first section of the caisson;

[0037] At the predetermined caisson location, fabricate and install the caisson cutting edge structure, pre-embed sensor wiring slots, install tilt sensors and pressure sensors in the sensor wiring slots, pre-position grouting pipes and conduits, and assemble or cast the first section of concrete caisson wall.

[0038] The third step is to simultaneously carry out excavation and automatic mud injection to aid sinking, so as to achieve excavation and sinking at the same time, until the caisson sinks to the designed depth.

[0039] The fourth step is mud replacement; once the caisson reaches the designed depth, cement slurry is injected through the grouting pipe to replace the mud slurry, replacing the grout around the caisson wall with cement slurry to ensure the compactness of the soil around the caisson and to flush out the original lubricating slurry to the ground to avoid polluting groundwater.

[0040] The excavation work in the third step is as follows: a long-arm excavator is used to excavate the soil inside the caisson; when the groundwater level is reached, an underwater excavator is used to continue excavating until the predetermined depth is reached.

[0041] The third step, the automatic mud injection and sedimentation assistance operation, specifically involves:

[0042] When the caisson wall and the caisson cutting edge structure sink, the mud-sheathed cutting edge fan ring segment squeezes the surrounding sand and gravel strata, forming a ring-shaped gap between the sand and gravel strata and the caisson wall above the mud-sheathed cutting edge fan ring segment.

[0043] The grouting pump is started, and the slurry enters the mud collection trough of each mud-jacketed cutting edge fan section through the grouting pipe. It then enters the gap between each annular section from the mud outlet at the top of each mud collection trough. This forms a mud lubrication layer between the sand and gravel stratum and the well wall of the caisson above each mud-jacketed cutting edge fan section, reducing the friction between the well wall and the sand and gravel stratum and thus aiding in settling. During the grouting process, the electrical control device controls the grouting pump to update the grouting pressure in real time according to the grouting pressure formula.

[0044] During the third step, the electronic control device performs a correction operation based on the signals from each tilt sensor; the correction operation is as follows:

[0045] The four tilt sensors correspond to any four adjacent directions out of the eight directions of the caisson;

[0046] The mud-free blade foot fan ring section corresponds to the four directions of east, south, west and north. The well wall of the caisson is in direct contact with the surrounding sand and gravel strata in these four directions. The sand and gravel strata play a positioning and guiding role for the well wall of the caisson in these four directions.

[0047] During the sinking of the caisson wall, when the measured value β of the tilt sensor corresponding to one or more mud-jacketed foot fan ring segments deviates from the vertical value by more than ±0.1 degrees, tilt adjustment action is performed.

[0048] The tilt adjustment action is:

[0049] The electrical control device controls the opening degree of the pressure regulating solenoid valve on the grouting pipe of the mud-jacketed cutting edge fan ring section corresponding to the raised end of the caisson to increase to 100%, while simultaneously controlling the closing of the pressure regulating solenoid valve on the grouting pipe of the mud-jacketed cutting edge fan ring section corresponding to the sunken end of the caisson. This causes the pressure of the mud lubrication layer on the outside of the raised end of the caisson to be higher than the pressure of the mud lubrication layer on the outside of the sunken end of the caisson. As a result, the caisson wall returns to a vertical state under the action of pressure difference. When the measured value β of all tilt sensors deviates from the vertical by less than or equal to 0.1 degrees and the measured value β of at least one tilt sensor is zero, the electrical control device adjusts the opening degree of all pressure regulating solenoid valves to 50%, completing the tilt adjustment operation.

[0050] The present invention has the following advantages:

[0051] The caisson cutting edge structure of this invention breaks with the conventional approach of existing technologies where the circumferential outer surface of the cutting edge structure protrudes entirely from the caisson wall to form a mud sleeve. In this invention, the mud-sleeve-free cutting edge fan-shaped section does not protrude from the caisson wall and does not participate in the formation of the mud sleeve. The corresponding advantage is that the caisson wall corresponding to the mud-sleeve-free cutting edge fan-shaped section is in direct contact with the soil (sand and gravel strata). During the caisson sinking process, the soil (sand and gravel strata) can limit, guide, and prevent deviation of the caisson through the mud-sleeve-free fan-shaped section, making it less prone to tilting during caisson sinking.

[0052] Meanwhile, in the past, the mud sleeve around the caisson was continuous in the circumferential direction, and its internal pressure was uniform (if the pressure was high at a certain location, the pressure would quickly even out due to the internal continuity), making it impossible to apply different pressures to different parts of the mud sleeve for correction. With the caisson cutting edge structure of this invention, the mud sleeve is divided into several segments in the circumferential direction by the well wall portion that contacts the soil (sand and gravel strata), thus providing a structural basis for applying different pressures to different parts of the mud sleeve for correction. Since L1:L2≥4:1, the well wall corresponding to the fan-shaped section without the mud sleeve accounts for less than a quarter of the circumferential direction, resulting in limited increase in soil friction.

[0053] The advantages of the caisson cutting edge structure can be summarized as follows: 1. It breaks the convention of the cutting edge structure having its circumferential outer surface protruding entirely from the caisson wall. 2. The caisson wall corresponding to the mud-sleeve-less cutting edge fan ring section plays a role in positioning, guiding, and preventing deviation of the caisson. 3. It provides a structural basis for applying different pressures to different parts of the mud sleeve for deviation correction. 4. The mud collection trough provides structural protection for grouting without impacting the sand and gravel strata, changing the grout flow that is horizontally directed towards the sand and gravel strata during grouting to flow upward towards the gap between the caisson wall and the sand and gravel strata. This is conducive to the rapid formation of the mud lubrication layer (the grout no longer impacts the sand and gravel strata, thus filling the gap between the caisson wall and the sand and gravel strata more quickly), and also prevents the mud from impacting the sand and gravel strata and entering the sand and gravel strata in large quantities, thus polluting the groundwater.

[0054] Since the grouting fluid is no longer flushed into the sand and gravel strata in large quantities, it not only avoids polluting the groundwater, but also significantly reduces the amount of grout used and accelerates the formation of the mud lubrication layer.

[0055] The intelligent control system for caisson sinking of the present invention detects the mud pressure at the mud inlet using a pressure sensor and detects whether the caisson deviates during sinking using an inclination sensor. It automatically adjusts the grouting pressure and achieves the correction function through an electronic control device. Compared with the prior art, the sinking process of the caisson in water-rich sandy gravel strata is more stable and reliable, with higher sinking efficiency. It can effectively avoid the phenomenon of caisson deviation and also avoid the large amount of grout (mud) entering the sandy gravel strata and causing groundwater pollution.

[0056] The rule of eight indicator lights on and off allows for the indication of tilt in eight directions when using four tilt sensors. During construction, the electrical control device determines the latest grouting pressure in real time based on the monitoring values ​​of the pressure sensors, ensuring that the grout reaches the ground level precisely. This satisfies the need for mud lubrication around the well wall while preventing excessive pressure that could cause too much grout to enter the gravel layer or result in excessive loss to the surface.

[0057] The construction method of the present invention is simple and the tilt of the caisson wall is clearly indicated. After the mud is replaced and solidified, the soil around the caisson wall is more solid and the caisson structure is safer.

[0058] By performing correction operations and adjusting the tilt angle, this invention can automatically correct the state of the caisson and restore it to vertical when it tilts during the sinking process. The correction is timely and does not require human intervention, thus improving the timeliness and quality of correction, avoiding human error, reducing labor requirements, and improving the construction quality of the caisson.

[0059] During the correction process, the electronic control device controls the indicator lights in the corresponding direction of the raised caisson to light up according to the rules of indicator light illumination. This can remind the staff to monitor the sinking posture of the caisson and guide the workers to take other correction measures in a timely and accurate manner to remove obstacles under the cutting edge. Attached Figure Description

[0060] Figure 1 This is a schematic diagram of the structure of the mud-free blade foot fan ring section.

[0061] Figure 2 This is a schematic diagram of the structure of the mud sleeve, cutting edge, and fan ring section.

[0062] Figure 3 This is a schematic diagram of the caisson cutting edge structure of the present invention.

[0063] Figure 4 This is a schematic diagram of the plan structure of a caisson using an intelligent caisson sinking control system.

[0064] Figure 5 yes Figure 4 AA view.

[0065] Figure 6 This is a schematic diagram of the electronic control structure of the present invention. Detailed Implementation

[0066] like Figures 1 to 6 As shown, the present invention provides a caisson cutting edge structure for caisson sinking construction, which is connected to the lower end of the caisson wall 1 and includes a radial outer ring wall, a radial inner ring wall and a bottom wall connected between the bottom ends of the radial outer ring wall and the radial inner ring wall. The radial inner ring wall is a trumpet shape with a smaller top and a larger bottom.

[0067] It includes a mud-jacketed cutting edge fan ring section 2 and a mud-jacket-free cutting edge fan ring section 3, which are alternately welded in the circumferential direction to form a caisson cutting edge structure.

[0068] Both the mud-jacketed cutting edge fan ring section 2 and the mud-jacket-less cutting edge fan ring section 3 include a radial outer ring section 4, a radial inner ring section 5, and a bottom fan ring section 6 connecting the bottom walls of the radial outer ring section 4 and the radial inner ring section 5; each radial outer ring section 4 is welded to form a radial outer ring wall, each radial inner ring section 5 is welded to form a radial inner ring wall, and each bottom fan ring section 6 is welded to form a bottom wall.

[0069] The outer surface of the radial outer ring 4 of the mudless blade fan ring 3 is flush with the outer surface of the well wall 1 of the caisson;

[0070] The radial outer ring 4 of the mud-sheathed cutting edge fan ring 2 is an upward-opening mud collection trough, and the radial outer wall of the mud collection trough protrudes from the outer surface of the well wall 1 of the caisson (that is, protrudes from the outer surface of the mud-sheathed cutting edge fan ring 3).

[0071] The sum of the circumferential lengths of the radial inner ring segments 5 of each of the mud-sleeve blade fan ring segments 2 is L1.

[0072] The sum of the circumferential lengths of the radial inner ring segments 5 of each mud-free blade fan ring segment 3 is L2;

[0073] L1:L2≥4:1; Each mud-collecting groove of the mud-collecting groove of the mud-sleeved foot fan section 2 is provided with a grouting hole 7, which is used to connect with the grouting pipe 8 pre-embedded in the caisson wall 1; The mud-sleeved foot fan section 2 is provided with 3 to 5 (including the two ends), preferably 4.

[0074] The caisson cutting edge structure of this invention breaks with the conventional approach where the circumferential outer surface of the cutting edge structure protrudes entirely from the caisson wall 1 to form a mud sleeve. In this invention, the mud-sleeve-free cutting edge fan-shaped segment 3 does not protrude from the caisson wall 1 and does not participate in the formation of the mud sleeve. The corresponding advantage is that the caisson wall 1 corresponding to the mud-sleeve-free cutting edge fan-shaped segment 3 is in direct contact with the soil (sand and gravel stratum). During the caisson sinking process, the soil (sand and gravel stratum) can limit, guide, and prevent deviation of the caisson through the mud-sleeve-free fan-shaped segment, making it less prone to tilting during caisson sinking.

[0075] Meanwhile, in the past, the mud sleeve around the caisson was continuous in the circumferential direction, and its internal pressure was uniform (if the pressure was high at a certain location, the pressure would quickly even out due to the internal continuity), making it impossible to apply different pressures to different parts of the mud sleeve for correction. With the caisson cutting edge structure of this invention, the mud sleeve is divided into several segments in the circumferential direction by the section of the well wall 1 that contacts the soil (sand and gravel strata), thus providing a structural basis for applying different pressures to different parts of the mud sleeve for correction. Since L1:L2≥4:1, the well wall 1 corresponding to the fan-shaped segment 3 without mud sleeve accounts for less than a quarter in the circumferential direction, resulting in limited increase in soil friction.

[0076] The advantages of the caisson cutting edge structure can be summarized as follows: 1. It breaks the convention of the cutting edge structure having its circumferential outer surface protruding entirely from the caisson wall 1. 2. The caisson wall 1 corresponding to the mud-sleeve-less cutting edge fan ring segment 3 plays a role in positioning, guiding, and preventing deviation of the caisson. 3. It provides a structural basis for applying different pressures to different parts of the mud sleeve for deviation correction. 4. The mud collection trough provides structural protection for grouting without impacting the sand and gravel strata, changing the grout flow that is horizontally directed towards the sand and gravel strata during grouting to flow upward towards the gap between the caisson wall 1 and the sand and gravel strata. This is conducive to the rapid formation of the mud lubrication layer (the grout no longer impacts the sand and gravel strata, thus filling the gap between the caisson wall 1 and the sand and gravel strata more quickly), and also prevents the mud from impacting the sand and gravel strata and entering the sand and gravel strata in large quantities, thus polluting the groundwater.

[0077] Since the grouting fluid is no longer flushed into the sand and gravel strata in large quantities, it not only avoids polluting the groundwater, but also significantly reduces the amount of grout used and accelerates the formation of the mud lubrication layer.

[0078] If the number of mud sleeve cutting edge fan ring segments is less than 3, it cannot provide effective support for grouting correction; if the number is more than 5, there is no obvious benefit and it also increases the difficulty of manufacturing (such as a significant increase in welding workload), so it is limited to 3-5.

[0079] An eaves plate 9 extends outward from the top of the radial inner wall of the mud collection trough. The outer diameter of the eaves plate 9 is the same as the outer diameter of the well wall 1 of the caisson. The eaves plate 9 and the top of the radial outer wall of the mud collection trough form a mud outlet 10.

[0080] The present invention also provides an intelligent control system for caisson sinking, which is particularly suitable for caisson construction in water-rich sandy and gravelly strata. The caisson includes a well wall 1, and the lower end of the well wall 1 is connected to the caisson cutting foot structure. There are four cutting foot fan ring sections 2 with mud sleeves and four cutting foot fan ring sections 3 without mud sleeves.

[0081] Includes grouting mechanism, sensing mechanism and electrical control device 18;

[0082] The grouting mechanism includes grouting pipes 8 pre-embedded in the well wall 1 of the caisson, and four grouting pipes 8 are provided in a one-to-one correspondence with the mud-sheathed cutting edge fan ring section 2;

[0083] The bottom end of the grouting pipe 8 is connected to the grouting hole 7 of the corresponding mud-sheathed blade fan ring section 2 and is used to grout into the corresponding mud collection tank.

[0084] The top of the grouting pipe 8 extends out of the well wall 1 of the caisson and is connected to the outlet pipe of the grouting pump 11 located on the ground. The inlet pipe of the grouting pump 11 is connected to the slurry container. Each grouting pipe 8 has a pressure regulating solenoid valve 12 connected in series at its top. The grouting pump 11 and the slurry container are both conventional technologies. The slurry container is not shown in the figure.

[0085] Sensor wiring slots 13 are pre-embedded at the bottom inner side of the caisson wall 1. East, southeast, south, southwest, west, northwest, north, and northeast are referred to as eight directions. Four sensor wiring slots are provided for any four adjacent directions of the eight directions of the caisson. For example, four sensor wiring slots 13 are provided for the west, northwest, north, and northeast parts of the caisson (when in use, the caisson is the center, so that the four sensor wiring slots correspond to the west, northwest, north, and northeast directions).

[0086] In fact, the four sensor wiring slots can correspond to any four adjacent directions in the eight directions of the caisson, and are not limited to the four directions of the west, northwest, north and northeast of the caisson; any change in the orientation of the four sensor wiring slots, as long as they still correspond to any four adjacent directions in the eight directions of the caisson, falls within the protection scope of this invention.

[0087] The sensor mechanism includes a pressure sensor 14, four tilt sensors 15, sensor wiring slots 13, and conduit 16. Each sensor wiring slot 13 is equipped with a set of tilt sensors 15. There is one pressure sensor 14, which is located in any one of the sensor wiring slots 13. A pressure measuring tube 31 is connected between the mud outlet 10 and the pressure sensor 14. The pressure measuring tube 31 is used by the pressure sensor 14 to monitor the mud pressure at the mud outlet 10.

[0088] Four conduits 16 are pre-embedded in the well wall 1 of the caisson. The conduits 16 are connected to the sensor wiring slots 13 one by one. The upper end of each conduit 16 extends out of the top of the well wall 1 of the caisson. The lines of the pressure sensor 14 and the tilt sensor 15 pass through the corresponding conduits 16 to the ground and are connected to the electrical control device 18.

[0089] The electrical control device 18 is located on the ground and connected to the display screen 17. The electrical control device 18 is connected to the grouting pump 11, the pressure regulating solenoid valve 12, the pressure sensor 14, and the tilt sensor 15. The electrical control device 18 uses a microcontroller or an industrial control computer.

[0090] The intelligent control system for caisson sinking of the present invention detects the mud pressure at the mud inlet using a pressure sensor, detects whether the caisson deviates during sinking using an inclination sensor 15, and automatically adjusts the grouting pressure and achieves the deviation correction function through an electronic control device 18. Compared with the prior art, the sinking process of the caisson in water-rich sandy gravel strata is more stable and reliable, with higher sinking efficiency, effectively avoiding caisson deviance and preventing a large amount of grout (mud) from entering the sandy gravel strata and causing groundwater pollution.

[0091] The electronic control device 18 has a housing with eight indicator lights 19 arranged circumferentially, corresponding to and used to indicate the eight directions: east, southeast, south, southwest, west, northwest, north, and northeast. Four tilt sensors 15 are aligned with their respective sensor wiring slots 13, located in any four adjacent directions of the caisson, with no two tilt sensors 15 located on the same diameter line of the caisson. Each tilt sensor 15 corresponds to two symmetrically distributed indicator lights 19 (e.g., the two indicator lights corresponding to east and west are symmetrically distributed).

[0092] During the sinking process, when the caisson tilts, one side of the caisson becomes the raised end and the opposite side becomes the sunken end; the electrical control device 18 controls the indicator light 19 in the direction corresponding to the raised end of the caisson to light up.

[0093] This invention also provides a construction method using the aforementioned intelligent control system for caisson sinking, for caisson construction in sandy and gravelly geological conditions with high groundwater levels, comprising the following steps:

[0094] The first step is to preset the parameters;

[0095] The grouting pressure of the grouting pump 11 is set to P1. The pressure sensor reading P increases with the sinking depth of the caisson. During construction, the electrical control device 18 determines the latest grouting pressure P1 in real time based on the pressure sensor reading P. P1 = R × P, where R is a dimensionless parameter and its specific value is determined by the staff. Its value range is 1.1 ≤ R ≤ 1.5.

[0096] The initial opening degree of each pressure regulating solenoid valve 12 is 50%. When the well wall 1 of the caisson is exactly vertical, the reading of each tilt sensor 15 is 0. The angle between the well wall 1 of the caisson and the vertical plane is α. When -0.1 degrees ≤ α ≤ 0.1 degrees, no tilt adjustment action is performed; otherwise, tilt adjustment action is performed.

[0097] The rule for 8 indicator lights to be on and off is as follows:

[0098] When the measured value β of the tilt sensor 15 corresponding to the mud sleeve foot fan ring segment 2 deviates from the vertical by more than ±0.1 degrees, the electronic control device 18 determines whether the location of the tilt sensor is the raised end or the sunken end of the caisson based on the positive and negative characteristics of β (the positive and negative characteristics of β relative to the vertical plane are defined in the algorithm of the electronic control device 18, either taking the angle when raised as a positive value or the angle when sunken as a positive value). If the location of the tilt sensor is located at the sunken end of the caisson, then the caisson part directly opposite the location of the tilt sensor is the raised end of the caisson; the electronic control device 18 controls the indicator light 19 (such as the east side light) corresponding to the raised end of the caisson to light up.

[0099] When two tilt sensors are located at the raised end of the caisson, the electronic control device 18 controls the indicator lights 19 corresponding to the locations of the two tilt sensors to light up simultaneously; if there is another indicator light 19 between the two lit indicator lights 19, the indicator light 19 between the two lit indicator lights 19 will also light up.

[0100] The rule of the eight indicator lights 19 on and off allows for the indication of tilt status in eight directions when using four tilt sensors 15. During construction, the electrical control device 18 determines the latest grouting pressure in real time according to the grouting pressure formula, ensuring that the grout reaches the ground level precisely. This satisfies the requirement of forming mud lubrication around the well wall 1 of the caisson while preventing excessive pressure that could cause too much grout to enter the gravel layer or be excessively lost from the ground.

[0101] The second step is to construct the first section of the caisson;

[0102] At the predetermined caisson location, fabricate and install the caisson cutting edge structure, pre-embed sensor wiring groove 13, install tilt sensor 15 and pressure sensor 14 in sensor wiring groove 13, pre-position grouting pipe 8 and conduit 16, and assemble or cast the first section of concrete caisson wall 1 according to the design drawings.

[0103] The third step is to simultaneously carry out excavation and automatic mud injection to aid sinking, so as to achieve excavation and sinking at the same time, until the caisson sinks to the designed depth.

[0104] The fourth step is mud replacement; after the caisson reaches the designed depth, cement slurry is injected through the grouting pipe 8 to replace the grout around the caisson wall 1 with cement slurry, so as to ensure the compactness of the soil around the caisson and to expel the original lubricating slurry (mud) from the ground to avoid polluting the groundwater.

[0105] The construction method of the present invention is simple and the tilt of the well wall 1 of the caisson is clearly indicated. After the mud is replaced and solidified, the soil around the well wall 1 of the caisson is more solid and the caisson structure is safer.

[0106] This invention addresses geological conditions in sandy and gravelly strata with high groundwater levels by employing a non-drainage sinking (underwater excavation) method for sinking operations. After the sandy and gravelly strata below the cutting edge are excavated, the well wall 1 of the caisson sinks under its own weight.

[0107] The excavation work in the third step is as follows: a long-arm excavator is used to excavate the soil inside the caisson; when the groundwater level is reached, an underwater excavator is used to continue excavating until the predetermined depth is reached.

[0108] The third step, the automatic mud injection and sedimentation assistance operation, specifically involves:

[0109] When the caisson wall 1 and the caisson cutting edge structure sink, the mud-sheathed cutting edge fan ring segment 2 squeezes the surrounding sand and gravel strata, forming a ring-shaped gap 20 between the sand and gravel strata and the caisson wall 1 above the mud-sheathed cutting edge fan ring segment 2.

[0110] The grouting pump 11 is started, and the slurry enters the mud collection troughs of each mud-sheathed cutting edge fan segment 2 through the grouting pipe 8. It then enters the annular gaps 20 from the mud outlets 10 at the top of each mud collection trough, forming a mud lubrication layer (commonly known as a mud sheath, usually circular or rectangular. In this invention, it is four annular segments) between the sand and gravel stratum and the well wall 1 of the caisson above each mud-sheathed cutting edge fan segment 2. This reduces the friction between the well wall 1 of the caisson and the sand and gravel stratum, thus aiding in settling. During the grouting process, the electrical control device 18 controls the grouting pump 11 to update the grouting pressure in real time according to the grouting pressure formula.

[0111] During the third step, the electronic control device 18 performs a correction operation based on the signals from each tilt sensor 15; the correction operation is as follows:

[0112] The four tilt sensors 15 correspond to any four adjacent directions in the eight directions of the caisson, such as southeast, southwest, northeast and northwest; no two tilt sensors 15 are located on the same diameter line of the caisson.

[0113] The mud-free blade foot fan ring section 3 corresponds to the four directions of east, south, west and north. The well wall 1 of the caisson is in direct contact with the surrounding sand and gravel strata in these four directions. The sand and gravel strata play a positioning and guiding role for the well wall 1 of the caisson in these four directions.

[0114] During the sinking of the caisson wall 1, when the measured value β of one or more tilt sensors 15 corresponding to the mud-jacketed foot fan ring section 2 deviates from the vertical value by more than ±0.1 degrees (i.e. the angle with the vertical plane is greater than ±0.1 degrees), tilt adjustment action is performed.

[0115] The tilt adjustment action is:

[0116] The electrical control device 18 controls the opening degree of the pressure regulating solenoid valve 12 on the grouting pipe 8 with mud-sleeved cutting edge fan ring 2 corresponding to the raised end of the caisson to increase to 100%, and at the same time controls the pressure regulating solenoid valve 12 on the grouting pipe 8 with mud-sleeved cutting edge fan ring 2 corresponding to the sunken end of the caisson to close (i.e., the opening degree is 0%), so that the pressure of the mud lubrication layer on the outside of the raised end of the caisson is higher than the pressure of the mud lubrication layer on the outside of the sunken end of the caisson, thereby restoring the caisson wall 1 to the vertical state under the action of pressure difference; when the measured value β of all tilt sensors 15 deviates from the vertical by less than or equal to 0.1 degrees and the measured value β of at least one tilt sensor 15 is zero, the electrical control device 18 adjusts the opening degree of all pressure regulating solenoid valves 12 to 50%, and completes the tilt adjustment operation.

[0117] Taking the example of a caisson being higher on the left and lower on the right, the principle of tilt angle adjustment is explained:

[0118] When the caisson wall is higher on the left and lower on the right (like a person's left foot leaving the ground and the body tilting to the right), the left side is the raised end of the caisson. The pressure of the mud lubrication layer on the outer left side of the caisson wall increases, becoming higher than the pressure of the mud lubrication layer on the outer right side of the caisson wall. Since the pressure of the mud lubrication layer increases as it goes lower (closer to the grouting holes of the mud collection trough), the mud lubrication layer that plays the greatest role in correcting deviation is the mud lubrication layer above and adjacent to the mud collection trough (the mud inside the mud collection trough does not have a corrective effect because it does not receive the reaction force from the sand and gravel strata), which is located at the bottom of the caisson, below the center of gravity of the caisson.

[0119] During the sinking process, the lower left side of the caisson is pushed to the right, causing the caisson to rotate around its center of gravity (to the left above the center of gravity and to the right below the center of gravity), thus restoring it to a vertical position.

[0120] By performing correction operations and adjusting the tilt angle, this invention can automatically correct the state of the caisson and restore it to vertical when it tilts during the sinking process. The correction is timely and does not require human intervention, thus improving the timeliness and quality of correction, avoiding human error, reducing labor requirements, and improving the construction quality of the caisson.

[0121] During the correction process, the electronic control device 18 controls the indicator light 19 in the direction corresponding to the raised end of the caisson to light up according to the rule of the indicator light 19 turning on and off. This can remind the staff to monitor the sinking posture of the caisson and guide the workers to take other correction measures in a timely and accurate manner to remove obstacles under the cutting edge.

[0122] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention without departing from the spirit and scope of the present invention. Any modifications or partial substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A caisson cutting edge structure, used for caissons, connected to the lower end of the caisson wall, including a radial outer ring wall, a radial inner ring wall, and a bottom wall connecting the bottom ends of the radial outer ring wall and the radial inner ring wall. The radial inner ring wall is in the shape of a trumpet, which is smaller at the top and larger at the bottom. Its features are: It includes a mud-jacketed cutting edge fan ring section and a mud-jacket-less cutting edge fan ring section. The mud-jacketed and mud-jacket-less cutting edge fan ring sections are alternately welded in the circumferential direction to form the caisson cutting edge structure. Both the mud-jacketed and mud-free cutting edge fan ring segments include a radial outer ring segment, a radial inner ring segment, and a bottom fan ring segment connecting the bottom walls of the radial outer ring segment and the radial inner ring segment; each radial outer ring segment is welded to form a radial outer ring wall, each radial inner ring segment is welded to form a radial inner ring wall, and each bottom fan ring segment is welded to form a bottom wall. The outer surface of the radial outer ring of the mud-free blade foot fan ring is flush with the outer surface of the well wall of the caisson; The radial outer ring of the mud-jacketed foot fan ring section is an upward-opening mud collection trough, and the radial outer wall of the mud collection trough protrudes from the outer surface of the well wall. The sum of the circumferential lengths of the radial inner ring segments of each of the mud-sleeve cutting edge fan ring segments is L1. The sum of the circumferential lengths of the radial inner ring segments of each mud-free blade fan ring segment is L2; L1:L2≥4:1; Each mud collection groove with mud sleeve cutting edge fan ring section is provided with grouting holes on its radial inner surface. The grouting holes are used to connect with the grouting pipes pre-embedded in the caisson wall; the mud sleeve cutting edge fan ring section is provided with 3 to 5 holes. An eaves plate extends outward from the top of the radial inner wall of the mud collection trough, and the outer diameter of the eaves plate is the same as the outer diameter of the well wall of the caisson; the eaves plate and the top of the radial outer wall of the mud collection trough form a mud outlet. The mud-sleeve-free cutting edge fan ring does not protrude from the caisson wall and does not participate in the formation of the mud sleeve; the caisson wall corresponding to the mud-sleeve-free cutting edge fan ring is in direct contact with the soil; during the caisson sinking process, the soil plays a role in limiting, guiding and preventing deviation of the caisson through the mud-sleeve-free fan ring; the mud sleeve is divided into several segments in the circumferential direction by the caisson wall parts in contact with the soil, providing a structural basis for applying different pressures to different parts of the mud sleeve for deviation correction.

2. A caisson sinking intelligent control system, wherein the caisson includes a caisson wall, and the lower end of the caisson wall is connected to the caisson cutting edge structure as described in claim 1, wherein four cutting edge fan ring sections with mud sleeves and four cutting edge fan ring sections without mud sleeves are provided; Its features are: Includes grouting mechanism, sensing mechanism and electrical control device; The grouting mechanism includes grouting pipes pre-embedded in the well wall of the caisson, with four grouting pipes corresponding one-to-one with the mud-sleeved cutting edge fan ring section; The bottom end of the grouting pipe is connected to the grouting hole of the corresponding mud-sheathed blade fan ring section and is used to grout into the corresponding mud collection tank. The top of the grouting pipe extends out of the well wall and is connected to the outlet pipe of the grouting pump located on the ground. The inlet pipe of the grouting pump is connected to the grout container. A pressure regulating solenoid valve is connected in series at the top of each grouting pipe. Sensor wiring slots are pre-embedded at the bottom of the inner wall of the caisson, with the east, southeast, south, southwest, west, northwest, north, and northeast directions referred to as the eight directions; four sensor wiring slots are provided for any four adjacent directions of the eight directions of the caisson. The sensor mechanism includes a pressure sensor, four tilt sensors, sensor wiring slots, and conduits. Each sensor wiring slot contains a set of tilt sensors. There is one pressure sensor located in any one of the sensor wiring slots. A pressure measuring tube is connected between the mud outlet and the pressure sensor. The pressure measuring tube is used by the pressure sensor to monitor the mud pressure at the mud outlet. Four conduits are pre-embedded in the wall of the caisson. Each conduit is connected to a corresponding sensor wiring slot. The upper end of each conduit extends out of the top of the caisson wall. The lines of the pressure sensor and tilt sensor pass through the corresponding conduits to the ground and are connected to the electrical control device. The electrical control device is located on the ground and connected to a display screen. The electrical control device is connected to the grouting pump, pressure regulating solenoid valve, pressure sensor and tilt sensor.

3. The intelligent control system for caisson sinking according to claim 2, characterized in that: The electronic control device has a housing with eight indicator lights along its circumference, which correspond to and are used to indicate the eight directions: east, southeast, south, southwest, west, northwest, north, and northeast. During the sinking process, when the caisson tilts, one side of the caisson becomes the raised end and the opposite side becomes the sunken end; the electrical control device controls the indicator light in the direction corresponding to the raised end of the caisson to light up.

4. The construction method of the intelligent control system for caisson sinking as described in claim 3, used for caisson construction in sandy and gravelly geological conditions with high groundwater levels, characterized in that... Follow these steps: The first step is to preset the parameters; The grouting pressure of the grouting pump is set to P1. The pressure sensor reading P increases with the sinking depth of the caisson. During construction, the electrical control device determines the latest grouting pressure P1 in real time based on the pressure sensor reading P. P1 = R × P, where R is a dimensionless parameter and its specific value is determined by the staff. Its value range is 1.1 ≤ R ≤ 1.

5. The initial opening degree of each pressure regulating solenoid valve is 50%. When the well wall of the caisson is exactly vertical, the reading of each tilt sensor is 0. The angle between the well wall of the caisson and the vertical plane is α. When -0.1 degrees ≤ α ≤ 0.1 degrees, no tilt adjustment action is performed; otherwise, tilt adjustment action is performed. The rules for the 8 indicator lights to turn on and off are as follows: When the measured value β of the tilt sensor corresponding to a mud-sleeve cutting edge fan ring section deviates from the vertical by more than ±0.1 degrees, the electronic control device determines whether the tilt sensor is located at the raised end or the sunken end of the caisson based on the positive and negative characteristics of β. If the tilt sensor is located at the sunken end of the caisson, then the part of the caisson directly opposite the tilt sensor is the raised end of the caisson; the electronic control device controls the indicator light corresponding to the raised end of the caisson to light up. When two tilt sensors are both located at the raised end of the caisson, the electronic control device will control the indicator lights corresponding to the locations of the two tilt sensors to light up simultaneously; if there are indicator lights between the two lit indicator lights, the indicator lights between the two lit indicator lights will also light up. The second step is to construct the first section of the caisson; At the predetermined caisson location, fabricate and install the caisson cutting edge structure, pre-embed sensor wiring slots, install tilt sensors and pressure sensors in the sensor wiring slots, pre-position grouting pipes and conduits, and assemble or cast-in-place the first section of concrete caisson wall. The third step is to simultaneously carry out excavation and automatic mud injection to aid sinking, so as to achieve excavation and sinking at the same time, until the caisson sinks to the designed depth. The fourth step is mud replacement; once the caisson reaches the designed depth, cement slurry is injected through the grouting pipe to replace the mud slurry, replacing the grout around the caisson wall with cement slurry to ensure the compactness of the soil around the caisson and to flush out the original lubricating slurry to the ground to avoid polluting groundwater.

5. The construction method according to claim 4, characterized in that: The excavation work in the third step is as follows: a long-arm excavator is used to excavate the soil inside the caisson; when the groundwater level is reached, an underwater excavator is used to continue excavating until the predetermined depth is reached. The third step, the automatic mud injection and sedimentation assistance operation, specifically involves: When the caisson wall and the caisson cutting edge structure sink, the mud-sheathed cutting edge fan ring segment squeezes the surrounding sand and gravel strata, forming a ring-shaped gap between the sand and gravel strata and the caisson wall above the mud-sheathed cutting edge fan ring segment. The grouting pump is started, and the slurry enters the mud collection trough of each mud-jacketed cutting edge fan section through the grouting pipe. It then enters the gap between each annular section from the mud outlet at the top of each mud collection trough. This forms a mud lubrication layer between the sand and gravel stratum and the well wall of the caisson above each mud-jacketed cutting edge fan section, reducing the friction between the well wall and the sand and gravel stratum and thus aiding in settling. During the grouting process, the electrical control device controls the grouting pump to update the grouting pressure in real time according to the grouting pressure formula.

6. The construction method according to claim 5, characterized in that: During the third step, the electronic control device performs a correction operation based on the signals from each tilt sensor; the correction operation is as follows: The four tilt sensors correspond to any four adjacent directions out of the eight directions of the caisson; The mud-free blade foot fan ring section corresponds to the four directions of east, south, west and north. The well wall of the caisson is in direct contact with the surrounding sand and gravel strata in these four directions. The sand and gravel strata play a positioning and guiding role for the well wall of the caisson in these four directions. During the sinking of the caisson wall, when the measured value β of the tilt sensor corresponding to one or more mud-jacketed foot fan ring segments deviates from the vertical value by more than ±0.1 degrees, tilt adjustment action is performed. The tilt adjustment action is: The electrical control device controls the opening degree of the pressure regulating solenoid valve on the grouting pipe of the mud-jacketed cutting edge fan ring section corresponding to the raised end of the caisson to increase to 100%, while simultaneously controlling the closing of the pressure regulating solenoid valve on the grouting pipe of the mud-jacketed cutting edge fan ring section corresponding to the sunken end of the caisson. This causes the pressure of the mud lubrication layer on the outside of the raised end of the caisson to be higher than the pressure of the mud lubrication layer on the outside of the sunken end of the caisson. As a result, the caisson wall returns to a vertical state under the action of pressure difference. When the measured value β of all tilt sensors deviates from the vertical by less than or equal to 0.1 degrees and the measured value β of at least one tilt sensor is zero, the electrical control device adjusts the opening degree of all pressure regulating solenoid valves to 50%, completing the tilt adjustment operation.

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