Underground diaphragm wall construction method

Abstract

The invention relates to an underground diaphragm wall construction method, belongs to the technical field of deep foundation support construction in building construction, and mainly solves the technical problems of groove wall collapse and large sediment control difficulty caused by unstable slurry performance in the grooving process of an underground diaphragm wall. The method comprises the steps that a reinforced concrete guide wall is used for guiding, a hydraulic grab bucket is used for excavating a groove section with the length of 6-8 m and the depth of 20-50 m, the density and viscosity of slurry are monitored in real time, bentonite slurry is added so that the density can be maintained to be 1.1-1.3 g / cm < 3 >, and a carboxymethyl cellulose solution is added so that the viscosity of a Markov funnel can be maintained to be 40-50 s; and after hole cleaning, the sediment thickness is ensured to be smaller than 100 mm, then a reinforcement cage is put down, and underwater concrete is poured through a guide pipe method. The method can effectively guarantee the stability of the groove wall and the concrete pouring quality, improves the integrity and anti-seepage performance of the wall body, and is mainly used for deep foundation pit supporting, underground structure anti-seepage and bearing wall construction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of deep foundation support construction. More particularly, the present application relates to a method for constructing a diaphragm wall. BACKGROUND

[0002] In the process of constructing a diaphragm wall, the stability of the trench wall is the key to ensuring the trenching accuracy, the subsequent installation of the reinforcement cage and the quality of concrete pouring. The traditional construction method relies on mud protection, but the performance of mud, especially the density and viscosity, can change easily during the dynamic excavation process. Insufficient mud density can result in the inability of the hydrostatic pressure to effectively resist the lateral pressure of the stratum, and insufficient mud viscosity can weaken the ability of the mud to carry debris and the effect of forming a mud skin, which can easily cause local necking or even collapse of the trench wall. Such trench wall instability problems not only increase the overage of concrete, but also can make it difficult to successfully lower the reinforcement cage, seriously affecting the construction efficiency and the quality of the wall.

[0003] On the other hand, the control of the sediment at the bottom of the trench section is another technical difficulty. During the trenching process, the cut soil particles are dispersed in the mud, and some particles gradually deposit at the bottom of the trench due to gravity during the circulation process. If the hole is not thoroughly cleaned, the residual thick sediment at the bottom of the trench can form a weak interlayer below the reinforcement cage. This greatly weakens the end bearing capacity of the diaphragm wall and can become a channel for leakage at the lower part of the wall, posing a long-term hidden danger to the load-bearing function and impermeability of the wall.

[0004] In solving the above problems, many difficulties have been encountered in construction. First, the control of mud performance has traditionally relied on manual sampling and testing at regular intervals, which has obvious hysteresis. Since real-time data cannot be obtained, the operator cannot timely detect the deterioration of the mud performance, and often makes remedial adjustments only after the problem occurs (such as a slight collapse), at which time the trench wall may have already been damaged, and the effect is half the effort. Second, for the judgment of the cleaning quality, the cleaning operation time or the observation of the appearance of the replaced mud is usually used as a rough standard, and there is a lack of quantitative acceptance basis. Only relying on experience can lead to insufficient cleaning time, incomplete sediment replacement, or excessive cleaning to ensure quality, resulting in waste of time and cost. Therefore, how to realize real-time regulation of mud performance and accurate control of sediment thickness has been a technical problem that has been trying to solve in the construction of diaphragm walls. SUMMARY

[0005] An object of the present application is to solve at least the above problems and to provide a method for constructing a diaphragm wall, which can effectively ensure the stability of the trench wall and the quality of concrete pouring, improve the integrity and impermeability of the wall, and is mainly used for deep foundation pit support, underground structure impermeability and load-bearing wall construction.

[0006] In order to achieve these objects and other advantages in accordance with the present application, a diaphragm wall construction method is provided, comprising the steps of: S1, constructing a guide wall, the guide wall is made of reinforced concrete structure, the depth of the guide wall is 1.5m to 2.0m, the width of the guide wall is 1.0m to 1.5m; S2, using the inner side of the guide wall as a guide, using a hydraulic grab to excavate a slot section at a predetermined position, the length of the slot section is 6m to 8m, the depth is 20m to 50m, using a mud pump to circulate and inject mud into the slot section during excavation; during the excavation cycle, the density and viscosity of the mud are monitored in real time using an online mud density meter and a Marsh funnel viscometer; When the density of the mud is monitored to be <1.1g / cm 3 , the density of the mud is increased by adding bentonite slurry to the circulation system, so that the density of the mud is maintained at 1.1g / cm 3 to 1.3g / cm 3 ; When the Marsh funnel viscosity of the mud is monitored to be <40s, the viscosity of the mud is increased by adding carboxymethyl cellulose solution to the circulation system, so that the Marsh funnel viscosity of the mud is maintained at 40s to 50s; S3, after the slot section is excavated, a hole cleaning process is performed, the mud containing sediment in the slot section is replaced using an air lifting device, the hole cleaning operation lasts for 30min to 60min; S4, after the hole cleaning is completed, the thickness of the sediment at the bottom of the slot section is measured using a measuring rope until the measured sediment thickness is <100mm; S5, lowering the reinforcement cage, the pre-bundled reinforcement cage is hoisted and lowered into the slot section; S6, pouring concrete, using the duct method for underwater concrete pouring, the inner diameter of the duct is 250mm to 300mm, the slump of the poured concrete is 180mm to 220mm, the pouring speed of the concrete is controlled at 3m 3 / h to 5m 3 / h, the bottom opening of the duct is always buried below the concrete liquid surface by 2m to 4m during pouring.

[0007] Preferably, the monitoring data of the online mud density meter and the online Marsh funnel viscometer are connected to a central processing unit; When the central processing unit identifies that the density of the mud decreases by more than 0.2g / cm 3 or the Marsh funnel viscosity decreases by more than 15s within 10min, an emergency mud strengthening instruction is automatically generated and executed, the execution process of the emergency mud strengthening instruction comprises the following steps: Synchronously add carboxymethyl cellulose solution with a concentration of 5% to 8% and barite powder with a particle size of 75 μm to 150 μm into the circulating system, wherein the addition flow of the carboxymethyl cellulose solution is controlled by a first metering pump to be 80 L / min to 120 L / min, and the addition amount of the barite powder is controlled by a second metering pump to be 3% to 5% of the total mass of the current circulating mud; The lifting speed of the hydraulic grab is automatically reduced to 0.3 m / min to 0.5 m / min, and the hydraulic grab is kept hovering at the depth position of the slot segment for 2 min to 3 min for stirring. Synchronously start the standby mud pump pre-set at the top of the slot segment to supplement the pre-stored stable mud into the slot segment at a flow rate of 20 m 3 / h to 30 m 3 / h, the stable mud has a density of 1.25 g / cm 3 to 1.35 g / cm 3 , and a Marsh funnel viscosity of 45 s to 55 s. The mud parameters are continuously monitored, and after the density is restored to 1.2 g / cm 3 or more and the Marsh funnel viscosity is restored to 45 s or more, the hydraulic grab is controlled to be slowly lifted at a speed of not more than 1.0 m / min.

[0008] Preferably, after the hydraulic grab is slowly lifted at a speed of not more than 1.0 m / min, a slot wall state evaluation and repair procedure is performed, which includes the following steps: The slot segment wall after emergency treatment is continuously scanned using an in-hole scanning imaging device, the scanning speed of the scanning imaging device is 1.5 m / min to 2.5 m / min, and the scanning resolution is 2 mm to 5 mm; when the scanning image identifies that the slot wall has a spalling area with a depth exceeding 50 mm or a visible crack with a width exceeding 3 mm, the spalling area or the visible crack is recorded as an abnormal section, and the depth position and range of the abnormal section are marked; A cement-bentonite composite slurry is accurately injected into the marked abnormal section through a grouting pipe, the water-cement ratio of the composite slurry is 0.6 to 0.8, the bentonite content is 10% to 15% of the mass of the cement, the Marsh funnel viscosity thereof is not less than 80 s, the grouting pressure is controlled to be 0.3 MPa to 0.5 MPa, and the duration of the constant pressure is 3 min to 5 min. After the local repair is completed, the hole cleaning process is performed again, the slot bottom sediment thickness is measured again using the measuring rope, and the subsequent steps of lowering the reinforcement cage and pouring concrete can be performed only when the measured sediment thickness is less than 100 mm.

[0009] Preferably, after the reinforcement cage is lowered and before the concrete is poured, an in-slot environment maintenance and monitoring procedure is implemented; the in-slot environment maintenance and monitoring procedure includes the following steps: Before the cage is lowered, an array of micro pressure sensors is installed on the side of the cage; After the cage is lowered, the vertical grouting pipe embedded in the cage is used to inject maintenance slurry with a flow rate of 0.5m 3 / h to 1.0m 3 / h and a density of 1.25g / cm 3 to 1.30 g / cm 3 , a Marsh funnel viscosity of 45s to 50s, for a duration covering at least the whole process from the completion of the cage lowering to the start of the concrete pouring; The array of micro pressure sensors is used to monitor the static pressure of the slurry at different depths in the trench in real time, with a monitoring frequency of once per minute; when the static pressure of the slurry at any monitoring point is lower than the theoretical value of the hydrostatic pressure calculated from the real-time monitored density of the slurry at that depth by more than 5%, or the density of the slurry at the bottom of the trench decreases by more than 0.05g / cm 3 in 1h, it is determined that an abnormality has occurred in the environment in the trench; once an abnormality is determined, maintenance hole cleaning is immediately started, and part of the slurry at the bottom of the trench is pumped out through the vertical grouting pipe, while high-density maintenance slurry with a flow rate of 1.5m 3 / h to 2.0m 3 / h and a density of 1.35g / cm 3 to 1.40 g / cm 3 , a Marsh funnel viscosity of 50s to 55s is injected, until the static pressure of the slurry at all monitoring points returns to normal and the density of the slurry at the bottom of the trench stabilizes at 1.25g / cm 3 or above.

[0010] Preferably, an intelligent anti-curling control program is implemented during the pouring of the concrete; the intelligent anti-curling control program comprises the following steps: A concrete pressure monitoring point is arranged every 5m in the depth direction of the trench section, and a pressure sensor is provided at each monitoring point to monitor the lateral pressure of the newly poured concrete in real time; The difference between the lateral pressure of the concrete and the pressure of the slurry at the same depth is calculated for each depth point, and when the pressure difference at any monitoring point exceeds 15kPa, the pouring scheme for that depth section is automatically adjusted; The adjustment scheme is to reduce the pouring speed of the concrete to 2m 3 / h to 3m 3 / h in the range of 2m above and 2m below the pressure abnormal section, and to increase the pipe embedment depth of the section to 4m to 5m; when the pressure difference falls within 10kPa and remains stable for 10min, the normal pouring speed and pipe embedment depth control are restored.

[0011] Preferably, a composite sealing reinforcement procedure is implemented at the joint between adjacent slot sections; the composite sealing reinforcement procedure comprises the following steps: At the joint between adjacent slot sections that have been formed, vertical milling is performed using a double-shaft slot milling machine, with a milling width of 100-150 mm and a milling depth that is 1.0-1.5 m greater than the current slot section depth; Immediately after milling, a water glass-bentonite composite slurry is injected into the gap formed by the milling through a pre-embedded grouting pipe, with a water glass content of 20-30% of the dry weight of the bentonite and an initial viscosity of no less than 60 s, and a grouting pressure of 0.8-1.2 MPa; After grouting is completed, an ultrasonic detection pipe is installed on both sides of the joint within a range of 0.5 m, and after 24 h of curing, continuity is detected using a cross-hole ultrasonic instrument; when the sound time value is greater than 250 μs or the amplitude loss is greater than 30% for more than 5% of the total number of measurement points, supplementary grouting is performed at the corresponding position, with a supplementary grouting pressure of 1.5-2.0 MPa.

[0012] Preferably, a layered pressure balance control procedure is implemented during construction of a super-deep slot section; the layered pressure balance control procedure comprises the following steps: In a slot section with a depth of more than 40 m, a pressure balance control zone is provided every 8 m along the depth direction; An independent mud circulation branch is provided in each control zone, and each branch is driven by a variable-frequency controlled centrifugal pump; the mud pressure at the bottom of each control zone is monitored in real time, and when the difference between the measured mud pressure of any control zone and the theoretical hydrostatic pressure of the control zone exceeds 20 kPa, the rotational speed of the centrifugal pump of the circulation branch of the control zone is automatically adjusted; The adjustment rule is as follows: when the measured pressure is too high, the pump speed is increased to 120-150% of the rated speed, and the mud circulation amount of the control zone is increased; when the measured pressure is too low, the pump speed is reduced to 50-80% of the rated speed, and the mud circulation amount of the control zone is reduced; the mud circulation amount of each control zone is independently controlled within a range of 15-25 m 3 / h, until the pressure difference of all control zones is stabilized within ±10 kPa. 3

[0013] ​Preferably, the descending speed of the concrete face in the duct is monitored in real time during the duct pouring process; when the descending speed exceeds 0.8 m / min, the concrete pumping speed is automatically reduced to maintain the descending speed in the range of 0.4 m / min to 0.6 m / min; when the descending speed is less than 0.3 m / min, the concrete pumping speed is automatically increased, and the duct vibrator is started, with the vibration frequency controlled in the range of 30 Hz to 40 Hz; meanwhile, the mud level in the groove section is monitored, and when the mud level drops by more than 200 mm, fresh mud is immediately supplemented through the standby mud supplementing system, with the supplementing flow being 1.2 to 1.5 times the pouring flow.

[0014] The present application at least includes the following beneficial effects: Firstly, by monitoring the mud density and the marshall funnel viscosity in real time and setting clear control thresholds (density 1.1-1.3 g / cm 3 , viscosity 40-50 s), the mud performance can be dynamically and accurately maintained in the best wall protection state. This effectively avoids the problems of groove wall collapse and necking caused by mud performance degradation, and provides a stable and regular groove space for subsequent processes.

[0015] Secondly, by strict hole cleaning process (air-lift replacement for 30-60 min) and combined with quantitative sediment thickness detection standard (<100 mm), the groove bottom sediment is thoroughly removed. This avoids the formation of weak interlayer, thereby ensuring that the end bearing force of the underground continuous wall meets the design requirements and significantly reducing the leakage risk at the bottom of the wall.

[0016] Thirdly, by strictly controlling the duct inner diameter, concrete slump, pouring speed and key duct burial depth (2-4 m), the underwater concrete pouring process is continuous and smooth, effectively preventing quality defects such as broken piles and mud inclusion caused by pouring interruption or concrete segregation, and finally forming a uniform, dense and well-integrated reinforced concrete wall.

[0017] Fourthly, the method of the present application changes the key links such as mud management and hole cleaning acceptance from experience-based qualitative operation to accurate control based on real-time data and quantitative standards, reducing the uncertainty, quality risks and rework probability in construction, thereby improving the overall construction efficiency and reliability of engineering quality.

[0018] Other advantages, objects and features of the present application will be partly embodied by the following description, and partly understood by those skilled in the art through research and practice of the present application. DETAILED DESCRIPTION

[0019] The present application will be further described in detail below with reference to the embodiments, so that those skilled in the art can implement the present application according to the description.

[0020] This invention provides a method for constructing a diaphragm wall, comprising the following steps: S1. Construction guide wall, wherein the guide wall is made of reinforced concrete, the depth of the guide wall is 1.5m to 2.0m, and the width of the guide wall is 1.0m to 1.5m; S2. Using the inner side of the guide wall as a guide, a hydraulic grab bucket is used to excavate a trench segment at a predetermined position. The length of the trench segment is 6m to 8m, and the depth of the trench segment is 20m to 50m. During the excavation process, a mud pump is used to circulate and inject mud into the trench segment. During the excavation circulation process, an online mud density meter is used to monitor the density of the mud in real time, and an online Marshall funnel viscometer is used to monitor the viscosity of the mud in real time. When the density of the mud was detected to be below 1.1 g / cm³ 3 At the same time, the density of the mud is increased by adding bentonite slurry to the circulation system, so that the density of the mud is maintained at 1.1 g / cm³. 3 Up to 1.3 g / cm 3 Within the range; When the Marvin funnel viscosity of the mud is detected to be below 40s, the viscosity of the mud is increased by adding carboxymethyl cellulose solution to the circulation system, so that the Marvin funnel viscosity of the mud is maintained in the range of 40s to 50s. S3. After the trench section is excavated, a hole cleaning process is carried out. An air lifter is used to replace the mud containing sediment in the trench section. The hole cleaning operation lasts for 30 to 60 minutes. S4. After cleaning the hole, use a measuring rope to measure the thickness of the sediment at the bottom of the tank section until the measured sediment thickness is less than 100mm. S5. Lower the steel cage: hoist the pre-tied steel cage as a whole and sink it into the trench section. S6. Concrete pouring: Underwater concrete pouring is performed using the tremie pipe method. The inner diameter of the tremie pipe is 250mm to 300mm, the slump of the poured concrete is 180mm to 220mm, and the pouring speed is controlled at 3m / s. 3 / h to 5m 3 / h, during the pouring process, the bottom of the duct is always buried 2m to 4m below the concrete liquid surface; In the above technical solution, in the implementation of the underground continuous wall construction method, first, the construction of the reinforced concrete guide wall is carried out. The guide wall depth can be selected as 1.5 m, 1.8 m or 2.0 m, and the width can be selected as 1.0 m, 1.2 m or 1.5 m, and the specific size is determined according to the geological conditions and the slotting depth. The guide wall is constructed by cast-in-place method, the concrete strength grade is not less than C25, and the reinforcement can use HRB400 grade steel bar, and the longitudinal and transverse steel bars are preferably between 12 mm and 16 mm in diameter, with a spacing of 150 mm to 200 mm. The guide wall formwork can select steel formwork or wooden formwork, and when installing, the verticality error of the inner side surface should be ensured to be not more than 5 mm, so as to ensure the guiding accuracy of the subsequent slotting. The top surface of the guide wall should be higher than the ground by 100 mm to 150 mm, so as to prevent the surface water from flowing into the slot.

[0021] The hydraulic grab bucket is used for construction in the slot segment excavation stage, and the grab bucket width is adapted to the slot segment width, and is usually 600 mm to 800 mm. When excavating, the inner side surface of the guide wall is used as the guide, and the excavation depth is controlled to be 0.8 m to 1.2 m per grab, and gradually excavated to the design depth, and the slot segment length can be selected as 6 m, 7 m or 8 m, and the depth can be determined to be between 20 m and 50 m according to the engineering needs. The mud circulating system includes a mud pump, a mud conveying pipeline and a sedimentation tank, and the mud pump can select a centrifugal type or a piston type, and the flow rate is preferably between 100 m 3 / h and 150 m 3 / h. The online mud density meter and the online Malvern funnel viscosity meter can be installed on the outlet pipeline of the mud circulating system to monitor the mud performance in real time. When the density is lower than 1.1 g / cm 3 , the bentonite slurry is injected through the feeding system, the bentonite can select sodium-based bentonite, and the amount of mixing is dynamically adjusted according to the real-time monitoring data. When the viscosity is lower than 40 s, the carboxymethyl cellulose solution is added, the concentration can be 1% to 2%, and the injection rate is controlled by the metering pump, so that the mud density is maintained between 1.1 g / cm 3 and 1.3 g / cm 3 , and the viscosity is maintained between 40 s and 50 s.

[0022] The hole cleaning process is performed after the trench is excavated to the design depth. The air-lift device is used to discharge the slurry containing sediment at the bottom of the trench. The air-lift device is a very mature existing device, which is usually composed of an air compressor, an air supply pipe and a sludge discharge pipe. The air compressor has a discharge capacity of not less than 6 m3 / min and a pressure of not less than 0.7 MPa. The hole cleaning time can be controlled between 30 min and 60 min according to the trench depth and sediment conditions. After the hole cleaning is completed, the sediment thickness at the bottom of the trench is measured by using a measuring rope combined with a sediment measuring box. The graduation value of the measuring rope should not be greater than 10 mm, and the subsequent process can be performed only when the sediment thickness is less than 100 mm. Then the pre-bundled steel reinforcement cage is hoisted and sunk as a whole. The diameter of the main reinforcement of the steel reinforcement cage can be selected from 25 mm to 32 mm according to the design, and the thickness of the protective layer is not less than 70 mm. Finally, the underwater concrete pouring is performed by using the duct method. The inner diameter of the duct can be selected from 250 mm, 280 mm or 300 mm. The slump of the concrete is controlled between 180 mm and 220 mm. The pouring speed should be 3 m3 / h to 5 m3 / h. The depth of the duct bottom opening embedded into the concrete liquid surface is always maintained at 2 m to 4 m.

[0023] The conventional construction method usually relies on manual sampling (such as once every 2-4 hours) to detect the density and viscosity of the slurry. The specific gravity balance and marshall funnel are used for offline measurement, which has serious hysteresis. The hole cleaning quality often depends on the experience of the operator, which is roughly judged by observing the appearance of the replaced slurry or only by the fixed hole cleaning time, and lacks quantitative acceptance standards such as “sediment thickness less than 100 mm”. The technical solution realizes the change from empirical and qualitative construction to data-based and quantitative control by using online slurry density meter and viscosity meter for real-time monitoring, and automatically adjusting the slurry performance according to the accurate numerical threshold (such as density 1.1-1.3 g / cm 3 , viscosity 40-50 s), and by using the measuring rope to measure the sediment thickness less than 100 mm, which significantly improves the accuracy of the process and the controllability of the results. Overall, by real-time monitoring and dynamic adjustment of the slurry performance, it helps to maintain the stability of the trench wall, and by mechanical hole cleaning and quantitative detection of the sediment thickness, it provides good conditions for the subsequent installation of the steel reinforcement cage and the pouring of the concrete, which helps to ensure the integrity and impermeability of the wall.

[0024] In another technical solution, the monitoring data of the online slurry density meter and the online marshall funnel viscosity meter are connected to a central processing unit; When the central processing unit identifies that the density of the slurry decreases by more than 0.2 g / cm 3 or the marshall funnel viscosity decreases by more than 15 s within 10 min, the slurry emergency strengthening instruction is automatically generated and executed. The execution process of the slurry emergency strengthening instruction includes the following steps: Synchronously add carboxymethyl cellulose solution with a concentration of 5% to 8% and barite powder with a particle size of 75 μm to 150 μm into the circulating system, wherein the addition flow of the carboxymethyl cellulose solution is controlled by a first metering pump to be 80 L / min to 120 L / min, and the addition amount of the barite powder is controlled by a second metering pump to be 3% to 5% of the total mass of the current circulating mud; The lifting speed of the hydraulic grab is automatically reduced to 0.3 m / min to 0.5 m / min, and the hydraulic grab is kept hovering and stirring at this depth position for 2 min to 3 min; Synchronously start the standby mud pump pre-set at the top of the groove section to supplement the pre-stored stable mud into the groove section at a flow rate of 20 m 3 / h to 30 m 3 / h, the stable mud has a density of 1.25 g / cm 3 to 1.35 g / cm 3 , and a Marsh funnel viscosity of 45 s to 55 s; The mud parameters are continuously monitored, and when the density is restored to 1.2 g / cm 3 or more and the Marsh funnel viscosity is restored to 45 s or more, the hydraulic grab is controlled to be slowly lifted at a speed of not more than 1.0 m / min.

[0025] In this technical solution, the central processing unit can be selected from an industrial programmable logic controller system. The system is connected with an online mud density meter and an online Marsh funnel viscosity meter through a 4-20 mA analog signal or a Modbus communication protocol, and the sampling frequency is set to 1 time per second. The system monitors the mud density and viscosity data in real time, and when it is identified that the density decreases by more than 0.2 g / cm³ within 10 min or the Marsh funnel viscosity decreases by more than 15 s within 10 min, the mud emergency strengthening program is automatically triggered.

[0026] When the emergency strengthening instruction is executed, the system first controls two metering pumps pre-integrated on the mud circulating loop dosing pipeline to synchronously add the treatment materials. The first metering pump is installed on the liquid outlet pipeline of the carboxymethyl cellulose solution storage tank, and delivers carboxymethyl cellulose solution with a concentration of 5% to 8%, and the addition flow is controlled to be between 80 L / min and 120 L / min. The second metering pump is connected with the feeding device of the barite powder bin, and is used to add barite powder with a particle size of 75 μm to 150 μm, and the addition amount is calculated as 3% to 5% of the total mass of the current circulating mud, and the quantitative addition is realized by adjusting the rotating speed of the feeder. At the same time, the system automatically reduces the lifting speed of the hydraulic grab to 0.3 m / min to 0.5 m / min, and keeps the hydraulic grab hovering and stirring at this depth position for 2 min to 3 min, so that the additives are fully mixed with the mud.

[0027] The standby mud pump that starts simultaneously can be a centrifugal mud pump, with its inlet connected to the stored stabilized mud tank and its outlet pipe connected to the tank section, with the flow rate controlled at 20 m³ / s. 3 / h to 30 m 3 The pump supplies stabilized mud with a density of 1.25 g / cm³ to the tank section. The pump operates at a rate between [number] and [number] hours. 3 Up to 1.35 g / cm 3 The Marsh funnel viscosity was 45 s to 55 s. The central processing unit continuously monitored the mud parameters, and when the density recovered to 1.2 g / cm³... 3 Once the viscosity of the Marsh funnel recovers to above 45 s, the hydraulic grab bucket is slowly raised at a speed not exceeding 1.0 m / min to complete the emergency treatment process.

[0028] Existing technologies, when dealing with rapidly deteriorating mud performance, typically rely on operators noticing anomalies (such as slight signs of tank wall collapse) and then manually adding treatment material to the circulation system, deciding whether to raise the grab bucket or replenish the mud. This manual intervention approach is slow and often misses the optimal treatment window. This new technology uses a central processing unit to monitor the rate of data change in real time (e.g., density decrease > 0.2 g / cm³ within 10 minutes). 3 The system automatically identifies emergency situations and immediately executes a standardized set of enhanced instructions, including the simultaneous addition of multiple materials, automatic deceleration and suspension of stirring, and rapid replenishment of reserve mud. This represents a leap from passive response to proactive early warning, and from manual operation to automated execution, significantly improving the efficiency and reliability of handling unexpected situations. Overall, through the automated control system and emergency response procedures, it can respond quickly when mud properties deteriorate rapidly, stabilizing mud properties through multi-pronged collaborative treatment, and providing effective protection for tank wall stability. The entire process reduces human intervention, improving processing efficiency and reliability.

[0029] In another technical solution, after the hydraulic grab bucket is slowly raised at a speed not exceeding 1.0 m / min, a tank wall condition assessment and repair procedure is performed, which includes the following steps: The wall of the tank section after emergency treatment is continuously scanned using an in-hole scanning imaging device. The scanning speed of the scanning imaging device is 1.5 m / min to 2.5 m / min, and the scanning resolution is 2 mm to 5 mm. When the scanned image identifies a spalling area with a depth of more than 50 mm or a visible crack with a width of more than 3 mm in the tank wall, the spalling area or visible crack is recorded as an abnormal section, and the depth, location and range of the abnormal section are marked. The cement-bentonite composite slurry is precisely injected into the marked abnormal section through a grouting pipe, the water-cement ratio of the composite slurry is 0.6 to 0.8, the bentonite content is 10% to 15% of the mass of cement, the Marsh funnel viscosity is not less than 80 s, the grouting pressure is controlled at 0.3 MPa to 0.5 MPa, and the duration of stable pressure is 3 min to 5 min; After completing the local repair, the hole cleaning process is performed again, the rope measurement is used to measure the thickness of the sediment on the groove bottom again, until the measured sediment thickness is less than 100 mm, and then the subsequent steps of lowering the reinforcement cage and pouring concrete can be performed.

[0030] In the above technical solution, the groove wall state evaluation and repair procedure is started after emergency treatment. The in-hole scanning imaging device can be an ultrasonic imager or an in-hole television system, which is lowered into the groove section through a cable and continuously scans at a speed of 1.5 m / min to 2.5 m / min. The scanning resolution of the device is set between 2 mm and 5 mm, which can clearly identify the defects on the surface of the groove wall. When the system identifies a spalling area with a depth exceeding 50 mm or a visible crack with a width exceeding 3 mm, the spalling area or visible crack is recorded as an abnormal section, and the depth position and range of the abnormal section are automatically recorded with an accuracy of within ±0.1 m.

[0031] The repair operation is performed using a special grouting pipe, which can be a steel pipe with a diameter of 25 mm and a one-way valve at the bottom. The cement-bentonite composite slurry is prepared using 42.5-grade ordinary portland cement and sodium-based bentonite, with a water-cement ratio controlled between 0.6 and 0.8, and a bentonite content of 10% to 15% of the mass of cement. After preparation, the Marsh funnel viscosity of the slurry is not less than 80 s, which is precisely injected into the marked abnormal section through a grouting pump at a pressure of 0.3 MPa to 0.5 MPa, with a stable pressure duration of 3 min to 5 min to ensure sufficient penetration and filling of the slurry.

[0032] The cement-bentonite composite slurry is prepared by using a step-by-step mixing process to ensure the uniformity and stability of the slurry. The preparation is as follows: first, slowly add sodium-based bentonite powder into clean water, and the mass ratio of clean water to bentonite is controlled at 8:1. Use a high-speed mixer to stir at a speed of 800 r / min for 15 min until the bentonite is fully dispersed and hydrated to form a colloidal slurry. Let it stand for at least 4 h before use. Then, add clean water into the mixing barrel, and the amount of clean water is determined according to the water-cement ratio of the final composite slurry of 0.6 to 0.8. Start the mixer and slowly add 42.5-grade ordinary portland cement during the mixing process, and the stirring speed is controlled at 300 r / min to 400 r / min, and the stirring time is not less than 3 min, until a uniform cement slurry is formed. Finally, slowly add the pre-hydrated bentonite slurry into the cement slurry while keeping the stirring. The amount of bentonite is calculated at 10% to 15% of the mass of cement. Then increase the stirring speed of the mixer to more than 600 r / min, and continue stirring for not less than 5 min to make the components fully mixed and uniform. Use a Marsh funnel viscometer to test the viscosity of the composite slurry, and ensure that it is not less than 80 s before use. This preparation method ensures that the bentonite is fully hydrated and uniformly mixed with the cement slurry through a step-by-step process, avoiding the formation of clumps, ensuring the stability, pumpability and thixotropy of the composite slurry, so that it can effectively penetrate and seal the cracks in the tank wall.

[0033] After completing the partial repair, the hole cleaning process is performed again. The air-lift device is used again to replace the slurry in the tank, and the hole cleaning time is controlled at 20 min to 40 min. The sediment thickness at the bottom of the tank is measured using a measuring rope and a sediment measuring box until the measured sediment thickness is less than 100 mm. After confirmation that the requirements are met, the subsequent steps of lowering the reinforcement cage and pouring concrete can be performed to ensure that the repaired tank section meets the construction quality requirements.

[0034] Traditional construction lacks fine detection means for the integrity of the trench wall after trenching or when problems occur. Even if there is suspicion of local defects, only blind and overall grouting treatment can be carried out, or the construction is continued to be ignored, leaving hidden dangers for subsequent processes. There is little practice in the prior art of using a borehole scanning imaging device to perform high-definition scanning (resolution 2-5 mm) and accurate positioning of defects (>50 mm peeling or >3 mm cracks) on the trench wall after emergency treatment. On this basis, the technical solution further accurately injects cement-bentonite composite slurry with high viscosity (≥80 s) at a specific pressure (0.3-0.5 MPa) to the defect site through a special grouting pipe, realizes the transformation from "fuzzy processing by experience" to "accurate repair by image", effectively improves the repair effect and reduces material waste. Overall, through advanced scanning imaging technology and targeted grouting repair process, trench wall defects can be effectively identified and treated, improving the integrity and stability of the trench wall and providing reliable protection for subsequent construction processes. The entire evaluation and repair process is quantifiable and controllable, reducing human error.

[0035] In another technical solution, an in-trench environment maintenance and monitoring procedure is implemented after the steel reinforcement cage is lowered and before the concrete is poured; the in-trench environment maintenance and monitoring procedure includes the following steps: Before the steel reinforcement cage is lowered, an array of micro pressure sensors is installed on the side of the steel reinforcement cage; After the steel reinforcement cage is lowered, through the vertical grouting pipe pre-embedded on the steel reinforcement cage, maintenance slurry with a density of 1.25 g / cm 3 to 1.30 g / cm 3 and a Malvern funnel viscosity of 45 s to 50 s is continuously injected into the trench bottom at a flow rate of 0.5 m 3 / h to 1.0 m 3 / h, with the injection duration covering at least the entire process from the completion of the steel reinforcement cage lowering to the start of the concrete pouring; Using the array of micro pressure sensors, the mud static pressure at different depths in the trench section is monitored in real time, with a monitoring frequency of 1 time per minute; when the mud static pressure value of any monitoring point is more than 5% lower than the theoretical value of the hydrostatic pressure calculated from the real-time monitored mud density and gravitational acceleration, or the density of the mud at the trench bottom decreases by more than 0.05 g / cm 3 in 1 h, it is determined that the in-trench environment is abnormal; once it is determined to be abnormal, maintenance hole cleaning is immediately started, and part of the mud at the trench bottom is pumped out through the vertical grouting pipe, while high-density maintenance slurry is injected at a flow rate of 1.5 m 3 / h to 2.0 m 3 / h, with the high-density maintenance slurry having a density of 1.35 g / cm 3 to 1.40 g / cm 3, the mud static pressure of all monitoring points returns to normal and the mud density at the tank bottom stabilizes at 1.25 g / cm 3 above.

[0036] In the above technical solution, the tank environment maintenance and monitoring program starts preparing before the reinforcement cage is lowered. The micro pressure sensor array can be selected from resistance type or optical fiber type pressure sensors, with a range of 0-1.0 MPa and an accuracy of not less than 0.5%FS. These sensors are pre-installed on the side of the reinforcement cage at an interval of 5 m, and are collected through a waterproof cable to the data acquisition box at the top of the cage. The data acquisition box is built-in with a power module and a wireless transmission module, and the monitoring frequency is set to 1 time per minute.

[0037] After the reinforcement cage is lowered, the maintenance mud is continuously injected into the tank bottom through the vertical grouting pipe pre-embedded on the reinforcement cage. The grouting pipe can be selected from a steel pipe with a diameter of 50 mm, and the bottom end is 0.3 m to 0.5 m away from the tank bottom. The maintenance mud is prepared by using sodium-based bentonite, and the density is controlled between 1.25 g / cm 3 and 1.30 g / cm 3 , with a Marsh funnel viscosity of 45 s to 50 s. The injection flow rate is controlled between 0.5 m 3 / h and 1.0 m 3 / h by a speed regulating screw pump, and the injection operation starts after the reinforcement cage is lowered and stops before the concrete is poured, to ensure continuous maintenance of the pressure in the tank.

[0038] The monitoring system receives the data of the pressure sensors at each depth in real time, and calculates the difference between the measured mud static pressure and the theoretical hydrostatic pressure at that point. The theoretical value is calculated according to the depth of the point and the real-time monitored mud density, and the calculation formula is P 理论 =ρ×g×h. In this formula, P 理论 represents the theoretical hydrostatic pressure, with the unit of kPa; ρ represents the real-time monitored mud density, with the unit of g / cm 3 ; g represents the acceleration of gravity, with a value of 9.8 m / s²; h represents the depth of the pressure sensor, with the unit of m. The system calculates the theoretical pressure value of each monitoring point in real time according to the formula, and compares and analyzes it with the measured value of the sensor.

[0039] When the measured pressure value of any monitoring point is lower than the theoretical value by more than 5%, or the mud density at the tank bottom decreases by more than 0.05 g / cm 3 within 1 hour, the system determines that the tank environment is abnormal. Once the abnormality occurs, the maintenance hole cleaning is immediately started, and the tank bottom part of the mud is pumped out through the vertical grouting pipe at a flow rate of 10 m 3 / h to 15 m 3 / h, and the mud is injected at a flow rate of 1.5 m 3 / h to 2.0 m3 The high-density maintenance mud is injected in parallel with the flow of the slurry. The high-density mud has a density of 1.35 g / cm 3 to 1.40 g / cm 3 , the Malvern funnel viscosity is 50 s to 55 s, until the pressure of all monitoring points returns to normal and the slurry density at the bottom of the tank is stabilized at 1.25 g / cm 3 above.

[0040] In the prior art, the slurry environment in the tank during the period from the completion of the placement of the reinforcement cage to the pouring of the concrete is in a state lacking effective monitoring. Changes in the slurry density and static pressure loss are difficult to be discovered in time, and problems are often discovered at the time of the placement of the guide pipe or at the initial stage of pouring, which is too late. The present technical solution realizes quantitative determination of environmental abnormalities (such as a pressure difference > 5% or a density drop > 0.05 g / cm 3 / h) through the micro pressure sensor array pre-installed on the reinforcement cage, which monitors the static pressure at different depths in real time at a frequency of 1 time per minute and compares with the theoretical hydrostatic pressure. Once an abnormality occurs, maintenance hole cleaning and mud supplementing for the bottom of the tank are immediately started, which is a significant progress from “unattended” to “real-time monitoring”, from “powerless” to “active maintenance”, and guarantees the stability of the tank wall during the critical intermittent period. Overall, through the integration of the monitoring and mud injection system on the reinforcement cage, real-time maintenance and monitoring of the environment in the tank are realized, targeted measures can be taken quickly when an abnormality occurs, and the stability of the tank wall during the critical period from the placement of the reinforcement cage to the pouring of the concrete is effectively guaranteed.

[0041] In another technical solution, an intelligent anti-circulation control program is implemented during the pouring of the concrete; the intelligent anti-circulation control program comprises the following steps: A concrete pressure monitoring point is arranged every 5 m in the depth direction of the tank section, and a pressure sensor is arranged at each monitoring point to monitor the lateral pressure of the newly poured concrete in real time; The difference between the lateral pressure of the concrete at each depth point and the mud pressure at the same depth is calculated, and when the pressure difference of any monitoring point exceeds 15 kPa, the pouring scheme of the depth section is automatically adjusted; The adjustment scheme is to reduce the pouring speed of the concrete to 2 m 3 / h to 3 m 3 / h in the range of 2 m above and 2 m below the pressure abnormal section, and increase the guide pipe burial depth of the section to 4 m to 5 m; when the pressure difference falls within 10 kPa and remains stable for 10 min, the normal pouring speed and guide pipe burial depth control are restored.

[0042] In the above technical solution, the intelligent anti-circulation control program is started synchronously during the concrete pouring process. The pressure monitoring system is composed of multiple vibrating wire pressure sensors, which are pre-installed on the outer wall of the duct at intervals of 5 m, forming an array of monitoring points along the depth direction. Each sensor has a range of 0-2.0 MPa and an accuracy of not less than 0.25% FS. The data is transmitted in real time to the central control unit through shielded signal cables, with a sampling frequency of 2 times per second.

[0043] The monitoring system calculates the difference between the concrete lateral pressure and the mud pressure at the same depth for each depth monitoring point in real time. The mud pressure value is provided by the mud pressure sensor installed on the corresponding depth groove wall, and the calculation formula of the pressure difference is ΔP = P 混凝土 -P 泥浆 When the pressure difference of any monitoring point in the system exceeds 15 kPa, the control unit automatically adjusts the pouring scheme for the abnormal section. The adjustment measures include: within the range of 2 m above and 2 m below the pressure abnormal section, the concrete pouring speed is reduced from the normal 3-5 m 3 / h to 2-3 m 3 / h, and at the same time, the duct depth of the section is increased from 2-4 m to 4-5 m by controlling the duct lifting mechanism.

[0044] The system continuously monitors the change of the pressure difference, and when the pressure difference falls within 10 kPa and remains stable for 10 minutes, it automatically restores the normal pouring speed and duct depth control. During the entire adjustment process, the control unit synchronously monitors the mud surface height in the groove section, and when the mud surface drops by more than 200 mm, it automatically starts the standby mud supplementing system to supplement fresh mud at a flow rate of 1.2-1.5 times the pouring flow rate, maintaining the stability of the mud surface in the groove.

[0045] The core of the intelligent anti-circulation control program implemented in this technical solution is dynamic regulation based on real-time data. In traditional duct method pouring construction, preventing concrete from circulating mainly relies on pre-set fixed parameters (such as uniform duct depth and pouring speed) and the experience of operators. It cannot perceive the actual state of the balance between concrete and mud pressure during pouring, and the adjustment is lagging and blind. The existing technology lacks the practice of arranging an array of pressure sensors along the depth direction to monitor the difference between concrete lateral pressure and mud pressure in real time. This technical solution automatically adjusts the pouring speed (reduced to 2-3 m 3h) and the pipe burial depth (increased to 4-5 m), realizing the leap from "fixed parameters, empirical judgment" to "real-time perception, dynamic optimization", providing data support and automatic means for effective control of flow around and guarantee of pouring quality. Overall, by monitoring the pressure difference between concrete and mud in real time and automatically adjusting the pouring parameters, it helps to reduce the occurrence of concrete flow around, ensure the concrete pouring quality, and maintain the stability of the trench wall. The system responds quickly, has high control accuracy, and reduces the lag of manual intervention.

[0046] In another technical solution, a composite sealing reinforcement program is implemented at the joint of adjacent trench sections; the composite sealing reinforcement program comprises the following steps: At the joint of the formed adjacent trench sections, a double-shaft trenching machine is used for vertical milling cleaning, the milling width is 100-150 mm, and the milling depth is 1.0-1.5 m greater than the current trench depth; After milling, immediately inject a water glass-bentonite composite slurry into the gap formed by milling through the pre-buried grouting pipe, the water glass content of the water glass-bentonite composite slurry is 20-30% of the dry weight of bentonite, the initial viscosity is not less than 60 s, and the grouting pressure is 0.8-1.2 MPa; After grouting is completed, install ultrasonic detection pipes within 0.5 m on both sides of the joint, and after 24 h of curing, use a cross-hole ultrasonic instrument for continuity detection; when the sound time value is greater than 250 s or the amplitude loss is greater than 30%, the number of measurement points exceeds 5% of the total number of measurement points, and supplementary grouting is performed at the corresponding position, and the supplementary grouting pressure is increased to 1.5-2.0 MPa.

[0047] In the above technical solution, the composite sealing reinforcement program is constructed at the joint of adjacent trench sections. The joint treatment is performed by vertical milling cleaning with a double-shaft trenching machine, which can be equipped with a milling power head with a power of 55-75 kW, the milling width is controlled between 100-150 mm, and the milling depth is 1.0-1.5 m greater than the current trench depth. The lowering speed of the trenching machine during milling operation is controlled at 0.5-0.8 m / min, and the lifting speed is controlled at 0.8-1.2 m / min, ensuring complete cleaning of the joint surface.

[0048] After milling, immediately inject the water glass-bentonite composite slurry into the gap formed by milling through the pre-embedded grouting pipe. The composite slurry is prepared using water glass with a modulus of 2.4 to 2.6 and sodium-based bentonite, and the water glass content is 20% to 30% of the dry weight of bentonite. When preparing the slurry, first mix the bentonite with water at a mass ratio of 1:8 to form a base slurry, and stir it in a high-speed mixer at a speed of not less than 800 r / min for 15 min to 20 min to preliminarily hydrate it. Then let the base slurry stand for not less than 4 h to ensure that the bentonite is fully expanded and hydrated to form a stable colloid. Before injection, add the measured water glass to the well-cured bentonite base slurry, with a water glass content of 20% to 30% of the dry weight of bentonite. Use a mixer to continuously stir at a speed of 400 r / min to 600 r / min for not less than 10 min to ensure uniform mixing of the water glass and bentonite slurry. After stirring is complete, let the prepared composite slurry stand for 30 min to allow the water glass and bentonite to fully react and the slurry properties to stabilize. After curing is complete, retest the slurry viscosity using a Marsh funnel viscometer to ensure that the initial viscosity is not less than 60 s. The slurry that has passed inspection should be used within 2 h to prevent performance degradation. This preparation method ensures that the components fully react and the slurry properties are stable through the step-by-step mixing and standing and curing process, so that it can meet the viscosity, stability and pumpability requirements of high-pressure grouting, thereby effectively ensuring the sealing effect of the joint.

[0049] Grouting is carried out using a double-cylinder grouting pump, with a grouting pressure controlled between 0.8 MPa and 1.2 MPa, and a grouting amount determined according to the volume of the gap, generally controlled between 0.15 m 3 / m and 0.25 m 3 / m. After grouting is complete, install ultrasonic detection pipes on both sides of the joint within a range of 0.5 m, the detection pipes can be PVC pipes with a diameter of 50 mm, the bottom of the pipe is sealed, and the pipe is filled with clean water. After 24 h of curing, use a cross-hole ultrasonic instrument to perform continuity detection, the transmitting probe and the receiving probe are lowered synchronously, the spacing between measuring points is 0.2 m. When the sound time value is greater than 250 μs or the amplitude loss is greater than 30%, more than 5% of the total measuring points, supplementary grouting is performed at the corresponding position, the supplementary grouting pressure is increased to 1.5 MPa to 2.0 MPa, and the retest is performed until it is qualified.

[0050] The composite sealing strengthening procedure implemented at the joint of adjacent slot sections provides a refined and verifiable joint treatment method. The treatment of the joint in the prior art is usually simple, for example, only using a wall brush to clean or using a conventional cement slurry for passive filling, and the treatment effect is difficult to quantify and evaluate, and the anti-seepage quality is uncertain. In the prior art, a double-shaft slot milling machine is less used to quantitatively mill the joint (width 100-150 mm, depth 1.0-1.5 m) to ensure the formation of a clean and regular gap. The present technical solution injects a specially prepared water glass-bentonite composite slurry immediately after milling, and finally detects the continuity of the joint quality by a cross-hole ultrasonic instrument. For unqualified points (sound time > 250 μs or wave amplitude loss > 30%), high-pressure supplementary grouting is carried out, realizing closed-loop quality control from "rough cleaning, empirical grouting" to "precise milling, performance grouting, non-destructive testing verification", and significantly improving the reliability and anti-seepage guarantee rate of the joint treatment. Overall, the method of combining mechanical milling cleaning and composite slurry grouting effectively improves the sealing performance of the slot section joint. Ultrasonic detection provides a quantitative evaluation basis for the quality of the joint, ensuring that the overall anti-seepage performance of the underground continuous wall meets the design requirements. The whole construction process is closely linked, and the quality control standard is clear.

[0051] In another technical solution, a layered pressure balance control procedure is implemented in the construction of a super-deep slot section; the layered pressure balance control procedure comprises the following steps: In a slot section with a depth of more than 40 m, a pressure balance control zone is set every 8 m along the depth direction; An independent mud circulation branch is set in each control zone, and each branch is driven by a variable frequency controlled centrifugal pump; the mud pressure at the bottom of each control zone is monitored in real time, and when the difference between the measured mud pressure of any control zone and the theoretical hydrostatic pressure of the zone exceeds 20 kPa, the rotation speed of the centrifugal pump of the circulation branch in the zone is automatically adjusted; The adjustment rule is: when the measured pressure is too high, increase the pump speed to 120%-150% of the rated speed, increase the mud circulation in the zone; when the measured pressure is too low, reduce the pump speed to 50%-80% of the rated speed, reduce the mud circulation in the zone; the mud circulation in each control zone is independently controlled in the range of 15 m 3 / h to 25 m 3 / h, until the pressure difference of all control zones is stable within ±10 kPa.

[0052] In the above technical solution, the layered pressure balance control program is implemented for the ultra-deep groove section with a depth exceeding 40 m. The pressure balance control system sets an independent control zone every 8 m along the groove section depth direction, and a vibrating string pore water pressure gauge with a range of 0-2.0 MPa and an accuracy of 0.1% FS is installed at the bottom of each control zone. An independent mud circulation branch is arranged for each control zone, and the branch is driven by a variable frequency controlled centrifugal pump with a rated flow of 25 m 3 / h and a rated head of 60 m. The pump outlet is connected to the grouting pipe at the corresponding depth through a DN80 steel pipe.

[0053] The system monitors the mud pressure at the bottom of each control zone in real time, and the sampling frequency is 1 time per second. The control unit calculates the difference between the measured mud pressure and the theoretical hydrostatic pressure of each control zone, and the theoretical hydrostatic pressure is calculated according to Ptheoretical=ρgh, where ρ is the real-time mud density (g / cm³), g is the acceleration of gravity (9.8 m / s²), and h is the depth of the control zone (m). When the pressure difference of any control zone exceeds 20 kPa, the system automatically adjusts the rotating speed of the centrifugal pump of the circulation branch of the zone. The adjustment rule is: when the measured pressure is too high, increase the pump speed to 120%-150% of the rated speed to increase the mud circulation of the zone; when the measured pressure is too low, reduce the pump speed to 50%-80% of the rated speed to reduce the mud circulation of the zone. The mud circulation of each control zone is independently controlled in the range of 15 m³ / h to 25 m³ / h until the pressure difference of all control zones is stable within ±10 kPa.

[0054] The traditional ultra-deep groove section construction adopts a single mud circulation system, and the same circulation flow and pressure control parameters are used throughout the groove section. This method cannot cope with the differences in formation pressure and mud performance at different depths, and is prone to cause excessive circulation at the shallow part and insufficient circulation at the deep part, resulting in imbalance of groove wall pressure and increasing the risk of hole collapse. The present technical solution sets a layered pressure balance control system to realize independent regulation and control of different depth intervals, and can accurately adjust the circulation parameters according to the actual pressure conditions of each zone, significantly improving the control accuracy and reliability of the groove wall stability during the construction of the ultra-deep groove section.

[0055] In another technical solution, during the guide pipe pouring process, the descending speed of the concrete surface in the guide pipe is monitored in real time; when the descending speed exceeds 0.8 m / min, the concrete pumping rate is automatically reduced to maintain the descending speed within the range of 0.4 m / min to 0.6 m / min; when the descending speed is less than 0.3 m / min, the concrete pumping rate is automatically increased, and the guide pipe vibrator is started, with a vibration frequency controlled within 30 Hz to 40 Hz; at the same time, the mud level in the groove section is monitored, and when the mud level drops by more than 200 mm, fresh mud is immediately supplemented through a standby mud supplementing system, with a supplementing flow of 1.2 times to 1.5 times of the pouring flow.

[0056] In the above technical solution, the radar or ultrasonic liquid level sensor is installed at the top of the conduit to monitor the descending speed of the concrete surface in the conduit in real time, and the sampling interval is 5 seconds. The sensor range is 0-50 m, and the accuracy is ±1 cm. The monitoring data is transmitted to the central control unit in real time, and the control unit has a built-in control algorithm to automatically adjust the concrete pumping rate according to the descending speed.

[0057] When the descending speed is monitored to exceed 0.8 m / min, the system automatically reduces the concrete pumping rate, adjusts the speed of the frequency conversion pump, and maintains the descending speed within the range of 0.4 m / min to 0.6 m / min. When the descending speed is lower than 0.3 m / min, the system automatically increases the concrete pumping rate, and starts the hydraulic vibrator installed in the upper part of the conduit, with a vibration frequency of 30 Hz to 40 Hz and an amplitude of 1 mm to 2 mm. The system synchronously monitors the mud surface height in the groove section, measures it with a throw-in static pressure liquid level meter, and immediately supplements fresh mud through the standby mud supplementing system when the mud surface drops by more than 200 mm. The mud supplementing flow is 1.2 to 1.5 times the current pouring flow, and the mud supplementing performance is consistent with the circulating mud.

[0058] In the traditional conduit pouring process, the descending speed of the concrete surface is measured by artificial hammering at regular intervals, usually once every 15-30 minutes, which has obvious hysteresis. The concrete pumping rate is manually adjusted by the pump operator based on experience, which cannot achieve real-time accurate control. The risk of conduit blockage mainly depends on the experience of the operator, and the preventive measures lack quantitative basis. The monitoring of the mud surface in the groove also relies on artificial measurement at regular intervals, and the mud supplementing is organized after the liquid level is found to be low, which is slow in response. The technical solution realizes real-time monitoring and dynamic adjustment of the concrete pouring process through the automatic monitoring and control system, can timely prevent problems such as conduit blockage and low mud surface, improves the reliability and continuity of the pouring process, and reduces the influence of human factors on the construction quality.

[0059] Although the embodiments of the present application have been disclosed as above, they are not limited to the applications listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application, and additional modifications can be easily realized by those skilled in the art, therefore the present application is not limited to specific details and the examples shown and described herein, without departing from the general concept defined by the claims and equivalent scope.

Claims

1. A method of constructing a diaphragm wall, characterised in that, The method comprises the following steps: S1, construction of the guide wall, the guide wall adopts a reinforced concrete structure, the depth of the guide wall is 1.5m to 2.0m, and the width of the guide wall is 1.0m to 1.5m; S2, using the inner side of the guide wall as a guide, a hydraulic grab is used to excavate a groove section at a predetermined position, the length of the groove section is 6m to 8m, and the depth is 20m to 50m, and a mud pump is used to circulate and inject mud into the groove section during the excavation process; during the excavation cycle, an online mud density meter and a Marsh funnel viscometer are used to monitor the density and viscosity of the mud in real time; When the density of the mud is monitored to be < 1.1 g / cm 3 , the density of the mud is increased by adding bentonite slurry into the circulating system, so that the density of the mud is maintained at 1.1 g / cm 3 to 1.3 g / cm 3 ; When the Marsh funnel viscosity of the mud is monitored to be less than 40s, the viscosity of the mud is increased by adding carboxymethyl cellulose solution to the circulation system, so that the Marsh funnel viscosity of the mud is maintained at 40s to 50s; S3, after the groove section is excavated, a hole cleaning process is performed, an air lifting device is used to replace the mud containing sediment in the groove section, and the hole cleaning operation lasts for 30min to 60min; S4, after the hole cleaning is completed, the thickness of the sediment at the bottom of the groove section is measured by using a measuring rope until the measured sediment thickness is less than 100mm; S5, the steel reinforcement cage is lowered, and the pre-bundled steel reinforcement cage is hoisted and sunk into the groove section; S6, pouring concrete, using the conduit method to pour underwater concrete, the inner diameter of the conduit is 250mm to 300mm, the slump of the poured concrete is 180mm to 220mm, the pouring speed of the concrete is controlled at 3m 3 / h to 5m 3 / h, and the depth of the bottom opening of the conduit embedded below the concrete liquid surface during pouring is always 2m to 4m.

2. The underground continuous wall construction method according to Claim 1, wherein The monitoring data of the online mud density meter and the online Marsh funnel viscometer are connected to a central processing unit; when the central processing unit identifies that the density of the mud drops more than 0.2 g / cm3 in 10 min 3 or the Ma funnel viscosity drops more than 15 s in 10 min, automatically generates and executes a mud emergency strengthening instruction, the execution process of the mud emergency strengthening instruction includes the following steps: Carboxymethyl cellulose solution with a concentration of 5% to 8% and barite powder with a particle size of 75μm to 150μm are simultaneously added to the circulation system, wherein the addition flow of the carboxymethyl cellulose solution is controlled by a first metering pump to be 80L / min to 120L / min, and the addition amount of the barite powder is controlled by a second metering pump to be 3% to 5% of the total mass of the circulating mud; The lifting speed of the hydraulic grab is automatically reduced to 0.3m / min to 0.5m / min, and the hydraulic grab is kept hovering and stirring at this groove depth position for 2min to 3min; The standby mud pump pre-set on the top of the tank section is started synchronously to supplement the pre-stored stable mud in the tank section at a flow rate of 20 m 3 / h to 30 m 3 / h, the stable mud has a density of 1.25 g / cm 3 to 1.35 g / cm 3 , and a marshall funnel viscosity of 45 s to 55 s. The mud parameters are continuously monitored and when the density returns to 1.2 g / cm 3 After the above, and after the Marsh funnel viscosity has returned to 45 s or more, the hydraulic grab is slowly raised at a speed of no more than 1.0 m / min.

3. The underground continuous wall construction method according to claim 2, wherein After the hydraulic grab is slowly lifted at a speed of not more than 1.0m / min, a groove wall state evaluation and repair program is performed, which comprises the following steps: An in-hole scanning imaging device is used to continuously scan the groove section wall after emergency treatment, the scanning speed of the scanning imaging device is 1.5m / min to 2.5m / min, and the scanning resolution is 2mm to 5mm; when the scanning image identifies that the groove wall has a spalling area with a depth exceeding 50mm or a visible crack with a width exceeding 3mm, the spalling area or the visible crack is recorded as an abnormal section, and the depth position and range of the abnormal section are marked; A cement-bentonite composite slurry is accurately injected into the marked abnormal section through a grouting pipe, the water-cement ratio of the composite slurry is 0.6 to 0.8, the bentonite content is 10% to 15% of the mass of cement, the Marsh funnel viscosity thereof is not less than 80s, the grouting pressure is controlled at 0.3MPa to 0.5MPa, and the stable pressure duration is 3min to 5min; After the local repair is completed, the hole cleaning process is performed again, the sediment thickness at the groove bottom is measured again by using a measuring rope, and only when the measured sediment thickness is less than 100mm, the subsequent steps of lowering the steel reinforcement cage and pouring concrete can be performed.

4. The underground continuous wall construction method according to claim 3, wherein After the steel reinforcement cage is lowered, before the concrete is poured, a trench environment maintenance and monitoring procedure is implemented; the trench environment maintenance and monitoring procedure comprises the following steps: Before the steel reinforcement cage is lowered, a micro pressure sensor array is installed on the side surface of the steel reinforcement cage; After the reinforcement cage is lowered, vertical grouting pipes embedded in the reinforcement cage are used to continuously inject maintenance slurry with a density of 1.25 g / cm 3 to 1.30 g / cm 3 at a flow rate of 0.5 m 3 to 1.0 m 3 / h into the bottom of the trench, the injection duration covering at least the entire process from the completion of the lowering of the reinforcement cage to the start of the pouring of the concrete, the maintenance slurry having a Malvern funnel viscosity of 45 s to 50 s. The micro pressure sensor array is used to monitor the mud static pressure at different depths in the groove section in real time, and the monitoring frequency is 1 time per minute; when the mud static pressure value of any monitoring point is lower than the theoretical value of hydrostatic pressure calculated by the real-time monitored mud density and gravitational acceleration by more than 5%, or the density of the mud at the bottom of the groove decreases by more than 0.05 g / cm 3 Within 1h, it is determined that the environment in the groove is abnormal; once it is determined to be abnormal, the maintenance hole cleaning is started immediately, the part of the mud at the bottom of the groove is drawn out through the vertical grouting pipe, and the high-density maintenance mud is injected at a flow rate of 1.5m 3 / h to 2.0m 3 / h, the density of the high-density maintenance mud is 1.35g / cm 3 to 1.40g / cm 3 , the Malten funnel viscosity is 50s to 55s, until the mud static pressure of all monitoring points returns to normal and the density of the mud at the bottom of the groove is stable at 1.25g / cm 3 above.

5. The underground continuous wall construction method according to claim 4, wherein During the pouring of the concrete, an intelligent anti-flowing-around control procedure is implemented; the intelligent anti-flowing-around control procedure comprises the following steps: Every 5 m in the depth direction of the trench section, a concrete pressure monitoring point is arranged, and a pressure sensor is arranged at each monitoring point to monitor the lateral pressure of the newly poured concrete in real time; The difference between the concrete lateral pressure at each depth point and the mud pressure at the same depth is calculated, and when the pressure difference of any monitoring point exceeds 15 kPa, the pouring scheme of the depth section is automatically adjusted; The adjustment scheme is: within the range of 2m above and 2m below the pressure abnormal section, the concrete pouring speed is reduced to 2m 3 / h to 3m 3 / h, and the pipe embedment depth of the section is increased to 4m to 5m; when the pressure difference value falls within 10kPa and remains stable for 10min, the normal pouring speed and pipe embedment depth control are restored.

6. The underground continuous wall construction method according to claim 5, wherein A composite sealing strengthening procedure is implemented at the joint between adjacent trench sections; the composite sealing strengthening procedure comprises the following steps: At the joint between adjacent trench sections that have been formed, a double-shaft trench milling machine is used for vertical milling and cleaning, the milling width is 100 mm to 150 mm, and the milling depth is 1.0 m to 1.5 m greater than the current trench depth; After the milling is completed, a sodium silicate-bentonite composite slurry is immediately injected into the gap formed by the milling through the pre-buried grouting pipe, the sodium silicate content of the sodium silicate-bentonite composite slurry is 20% to 30% of the dry weight of the bentonite, the initial viscosity is not less than 60 s, and the grouting pressure is 0.8 MPa to 1.2 MPa; After the grouting is completed, ultrasonic detection pipes are installed within a range of 0.5 m on both sides of the joint, and after 24 h of curing, a cross-hole ultrasonic instrument is used for continuity detection; when the sound time value is greater than 250 μs or the wave amplitude loss is greater than 30% of the total number of measurement points, supplementary grouting is performed at the corresponding position, and the supplementary grouting pressure is increased to 1.5 MPa to 2.0 MPa.

7. The underground continuous wall construction method according to claim 6, wherein A layered pressure balance control procedure is implemented in the construction of the super-deep trench section; the layered pressure balance control procedure comprises the following steps: In a trench section with a depth of more than 40 m, a pressure balance control zone is set every 8 m along the depth direction; An independent mud circulation branch is arranged in each control zone, and each branch is driven by a variable frequency controlled centrifugal pump; the mud pressure at the bottom of each control zone is monitored in real time, and when the difference between the measured mud pressure of any control zone and the theoretical hydrostatic pressure of the control zone exceeds 20 kPa, the rotational speed of the centrifugal pump of the circulation branch of the control zone is automatically adjusted; The adjustment rule is: when the measured pressure is higher, increase the pump speed to 120%-150% of the rated speed, increase the mud circulation rate of the control area; when the measured pressure is lower, reduce the pump speed to 50%-80% of the rated speed, reduce the mud circulation rate of the control area; the mud circulation rate of each control area is independently controlled in the range of 15m 3 / h to 25m 3 / h, until the pressure difference of all control areas is stable within ±10kPa.

8. The underground continuous wall construction method according to claim 1, characterized by, During the pipe pouring process, the descending speed of the concrete surface in the pipe is monitored in real time; when the descending speed exceeds 0.8 m / min, the concrete pumping rate is automatically reduced to maintain the descending speed within the range of 0.4 m / min to 0.6 m / min; when the descending speed is less than 0.3 m / min, the concrete pumping rate is automatically increased, and a pipe vibrator is started, with a vibration frequency controlled at 30 Hz to 40 Hz; at the same time, the mud surface height in the trench section is monitored, and when the mud surface drops by more than 200 mm, fresh mud is immediately supplemented through a standby mud supplementing system, and the supplementing flow rate is 1.2 times to 1.5 times the pouring flow rate.