Method for rapid shield construction of sandstone-mudstone interbedded belt collaborative shield

Abstract

To solve the problem of shield tunneling in sandstone-mudstone interbedded strata, based on the combined exploration report, the present invention uses advanced detection facilities to obtain formation information, and based on this, conducts shield segmentation and working shaft layout, determines the shield mode and cutterhead scheme, the belt conveyor muck transportation scheme and key shield parameters. The attitude and working parameters of the belt conveyor are designed for coordinated shield tunneling (horizontal turning angle, longitudinal slope angle, shield speed). Based on the detection of soil properties and image recognition of the muck, a warning and self-response plan for muck transportation failure is established; a rapid rectification measure for shield deviation is set, a synchronous slurry adaptability selection scheme and a rapid shield settlement control material scheme for sandstone-mudstone interbedded strata are formed, and a method for inspection and correction of the scheme is constructed, and a rapid shield settlement monitoring system and a settlement maintenance plan are set. The present invention can avoid situations such as shield shutdown for maintenance and inefficient muck discharge, establish a perfect settlement and deviation control system, and achieve rapid shield tunneling in sandstone-mudstone interbedded strata.

Description

Technical Field

[0001] The invention belongs to the technical field of tunnel shield construction, and in particular relates to a sand-mudstone interlayer belt coordinated shield rapid shield construction method. Background Art

[0002] Due to the advantages of shield technology such as high safety, fast construction speed and small surface settlement, it is increasingly used in various underground engineering scenarios such as urban subways, intercity railways and water tunnels. Sandstone interbedded rock mass is a unique combination of sedimentary or metamorphic strata formed by the combined action of natural forces and geological stresses in the long geological history; sandstone is a rock formed by the accumulation of sand particles, with a particle size usually between 0.0625 and 2 mm; while mudstone is composed of clay and silt particles with a particle size less than 0.0625 mm. The deposition of these two types of rocks occurs alternately, forming the so-called sandstone interbedded rock.

[0003] When the shield machine works in the sand-shale interlayer, its excavation speed is limited due to the characteristics of the stratum, such as soft on the top and hard on the bottom, and multi-layer structure. Among them, the shield excavation and the transportation of slag in the sand-shale interlayer are the key factors affecting its construction speed. In most existing projects, rail transportation is usually used to transport slag and pipe segments inside the tunnel. When the rail transportation is transporting slag and materials back and forth, the shield will stop excavating. For tunnels in composite strata such as sand-shale interlayer, the shield rate is in a state of long-term change due to the influence of variable geological conditions, which makes the slag excavation volume and slag characteristics show unstable characteristics; thus, it is difficult to organize the construction of rail slag transportation and the economic benefits are reduced. In addition, the time required for rail transportation of slag is long, which leads to a significant extension of the downtime of the shield machine in the sand-shale interlayer, which not only affects the construction progress, but also poses a safety hazard. Therefore, the gantry crane combined with rail transportation technology currently used can no longer meet the needs of efficient excavation and rapid slag discharge of the sand-shale interlayer shield.

[0004] Drawing on the belt conveyor for transporting crushed ore in mining engineering, the belt conveyor has gradually been introduced into the shield tunneling field as an efficient tool for transporting muck. Its excellent performance in transporting muck has been widely recognized, and the application solutions have quickly matured. In most cases, using a belt conveyor for muck transportation can avoid the shield machine from stopping for muck removal, reduce labor costs, and has higher economic efficiency and faster construction speed. However, when the belt conveyor serves complex working conditions, such as the interbedded sandstone and mudstone, multiple longitudinal slopes, and multiple corners in this study, problems such as muck adhesion or slipping, belt deviation, and belt slipping will occur without belt conveyor control means, seriously affecting the transportation rate and construction safety. In addition, when the shield tunneling speed fluctuates greatly in a short section, the muck output and muck characteristics at the muck outlet of the shield machine also vary accordingly. Therefore, it is necessary to conduct in-depth research on controlling the working states of the belt conveyor transmission rate, transportation passability, etc., and solving the problem of poor dynamic matching between muck removal and transmission.

[0005] In response to the problems that occur in shield tunneling and muck discharging in the interbedded sandstone and mudstone, domestic research has improved the shield-belt conveyor transmission technology by adopting solutions such as muck improvement, adjusting auxiliary equipment, and shield machine tunneling parameters, which has overall improved the construction production efficiency and economic benefits. However, there are still many problems that need to be further improved:

[0006] 1. When carrying out shield tunneling operations in composite strata, due to the frequent changes in the characteristics of the rock and soil mass at the working face, such as the composite situation, weathering degree, and joint development degree, the differences may be relatively large in a short section. Therefore, the current technical means relying solely on geological exploration reports to guide the shield machine's progress may lack pertinence and it is difficult to make predictive response measures in a timely manner for potential dangerous working conditions such as thin interlayers and interbedded heterogeneities in the interbedded sandstone and mudstone, and prevent disasters such as local collapses and sidewall instabilities caused by them.

[0007] 2. The interbedded sandstone and mudstone belong to a stratum with unstable and uneven lithology, and it is extremely easy to cause shield disasters such as shield machine head lifting and deviation during tunneling. The research on the rapid rectification method for shield attitude deviation is not sufficient, and many are aimed at soft soil strata, with limitations in applicability.

[0008] 3. For composite strata such as the interbedded sandstone and mudstone, the types and characteristics of their shield muck also vary greatly in a short section. If only using a belt conveyor to directly transport shield muck, due to the unevenness and significant differences in physical properties of the muck, it is very likely to occur the situation of muck transportation failure (muck slipping, muck adhesion), seriously threatening the safety of construction workers. In addition, the muck generated by the shield in the interbedded sandstone and mudstone area often has a high water content. Transporting the muck directly by a continuous belt conveyor without water collection and drainage treatment will not only increase the transportation burden, but may also cause the muck water to leak obliquely, deteriorating the construction environment in the tunnel.

[0009] 4. Since the shield line may have large turning angles and slope angles, and the belt conveyor route is more curved, the belt conveyor is very likely to have problems such as belt deviation and belt slippage during zigzag transportation. The existing patent lacks anti-deviation design for zigzag transportation of belt conveyors, and belt deviation correction is mainly achieved by adjusting the parameters of auxiliary equipment such as rollers. The belt conveyor's slag transportation work needs to be suspended for maintenance, which seriously slows down the construction progress and reduces construction efficiency.

[0010] 5. The existing belt conveyor slag technology lacks efficient transmission failure monitoring, early warning and remedial measures. If the slag slippage and adhesion are not discovered in time, it is very easy to cause the belt conveyor to fail, causing a series of safety problems. After the failure problem is discovered, it is often solved by stopping the machine for maintenance and posture verification, which not only affects the shield operation and slows down the construction period, but also has poor repair results, and many subsequent problems will still occur.

[0011] 6. When conducting shield tunneling in sand-shale interlayers, the shield tunneling rate is mainly limited by the complex characteristics of the strata and is at a low level. Among them, the effect of grouting technology on settlement and stratum stability control during shield tunneling is the core issue that needs to be paid attention to in improving the construction rate of sand-shale interlayer shield tunneling. Existing patents rarely pay attention to the adaptability of grouting materials and grouting technology in sand-shale interlayer environments, and fail to establish targeted settlement and deformation suppression solutions. Summary of the invention

[0012] The present invention provides a sand-mudstone interlayer belt-coordinated shield rapid shield construction method to solve the problems existing in the above-mentioned belt conveyor in the application of sand-mudstone interlayer. The present invention divides the shield section and optimizes the shield mode according to the actual stratum conditions of the sand-mudstone interlayer shield, and at the same time limits the shield parameters to a certain extent, so as to ensure that the shield slag has stable characteristics. On this basis, a slag temporary storage bin is set to process the slag to increase the adaptability of the slag to belt transportation, and at the same time, a slag characteristic detection device is arranged therein to automatically analyze the monitoring data for adhesion and sliding warning. According to the slope inclination angle, horizontal turning angle and other information of the shield route, the appropriate initial posture of the continuous belt conveyor is determined, and at the same time, components such as self-aligning rollers are set to adapt to the shield turning angle, so as to increase the deformability of the belt conveyor and the workability of the curved route. According to the slag characteristics and warning information, the transportation inclination angle is dynamically adjusted for the warning batch of slag, so as to realize the self-adjustment of the belt conveyor posture adaptability, thereby reducing the occurrence of slag sliding and other conditions. According to the information of excavation speed, excavation diameter, soil density, etc., the excavation rate is predicted and the maximum transmission capacity of the belt conveyor is designed; the continuous belt conveyor speed regulation linkage control is carried out during the excavation process in combination with the discharge conditions of the soil temporary storage bin and the soil treatment bin to reduce the occurrence of the continuous belt conveyor no-load operation phenomenon. Specifically, the technical scheme of the present invention is as follows:

[0013] A sand-mudstone interlayer belt-coordinated shield fast shield construction method, characterized by comprising the following steps:

[0014] S1. Obtain the geological shield tunnel section survey report as the original data, and deploy shield advanced detection facilities; establish an advanced detection plan considering the mileage of the shield tunnel section and the formation differences between sections, delimit the shield segments and deploy construction working shafts:

[0015] Conduct the formation information collection work before shield construction to form a geological survey report; for the interbedded sandstone and mudstone formation, adopt the air pressure array-driven hammering seismic source feedback - fiber optic demodulation to achieve the three-characteristic advanced detection of water, rock, and fissures;

[0016] Take the actual situation of the interbedded sandstone and mudstone as the final decision-making condition, control the segment mileage within 3 - 8 km, and reduce the non-advancing operations such as the starting, turning around, and transferring of the shield machine. According to the groundwater abundance - rock mass reliability - fracture development degree of 0 - 50 m ahead obtained and combined with the geological exploration report information, set working shafts at the continuous and stable formation locations, and the construction spacing of the working shafts is 1.5 km - 3.5 km;

[0017] S2. Determine the shield mode and cutterhead transformation plan according to the characteristics of the interbedded sandstone and mudstone:

[0018] If the distance between adjacent formation characteristic layers on the tunneling route is mostly 100 m or more, and the geological data shows that the moderately weathered rock cores are medium - long columnar, the fissures are underdeveloped - moderately developed, the rock mass is relatively intact, the rock quality is relatively hard, and the groundwater level is relatively low, the earth pressure - slurry double - mode shield or earth pressure balance shield can be adopted and a cutterhead transformation plan can be set to prevent the attitude deviation caused by rapid shield tunneling under uneven formations; if the distance between adjacent formation characteristic layers is concentrated below 100 m, or the sandstone and mudstone have strong weathering characteristics, or the mileage of the shield section with soft - upper - hard - lower, mudstone intercalated with thin sandstone, or sandstone intercalated with mudstone exceeds 60%, then the earth pressure - slurry double - mode shield with partial slurry wall protection or the slurry shield mode should be preferentially adopted for this section;

[0019] For the shield tunneling of the interbedded sandstone and mudstone, set a reverse tool holder on the spoke - type panel cutterhead to realize the orderly switching of button cutters and smooth - faced wide - edge cutters; set a retractable splitting cone drill, an advanced reinforcement device, and a profiling over - excavation cutter to reduce the disturbance and settlement of the surrounding formation and provide a rapid rectification measure for the shield attitude deviation;

[0020] S3. Determine the belt conveyor muck transportation plan: The belt conveyor group used for shield muck transportation includes a muck distributor, a horizontal continuous belt conveyor, and a vertical belt conveyor;

[0021] The muck distributor is provided with two storage bins, one muck temporary storage bin, and one muck re - treatment bin at the end; when the temporary storage bin and the treatment bin reach a certain volume, centralized soil discharge is carried out, and the muck is transferred to the horizontal continuous belt conveyor for long - distance horizontal transportation;

[0022] The tail of the muck reprocessing bin is connected to the muck temporary storage bin, enabling the re - mixing of muck after processing. Inside the muck temporary storage bin, there are portable mechanical soil samplers, cross - shear devices, and rapid direct shear equipment. By combining image recognition, the soil properties of batches of soil can be detected (rough particle size of materials, internal friction angle, muck density, muck fluidity state).

[0023] On the back of the downward section of the belt, an active flapper cleaner and a scraper cleaner are respectively set. At the front end, multiple groups of high - pressure water flushing devices are set as adhesion treatment equipment.

[0024] The vertical belt conveyor is set at the end of the horizontal continuous belt conveyor or in the vertical working shaft, and is used for vertical transportation according to the height requirement of the muck. When the vertical belt conveyor transports the muck to its end, the muck falls into the muck pool for storage or treatment, and finally the muck discharging work is completed.

[0025] S4. Based on the shield route planning scheme, design the horizontal rotation angle of the continuous belt conveyor in coordination with the shield attitude.

[0026] Among them, in the turning section with a flat circular curve radius greater than 1200m, self - aligning rollers are used to apply a centrifugal inclination angle of 2 - 8° in the direction perpendicular to the belt.

[0027] In the turning section with a flat circular curve radius of 400 - 1200m, self - aligning rollers are used to apply a centrifugal inclination angle of 5 - 10°. By utilizing the self - weight of the muck and combining with the tension driving machine, self - tensioning of belt transportation is achieved.

[0028] S5. Considering the slope angle and lifting height requirements on the shield route, design the vertical inclination angle of the continuous belt conveyor in coordination with the shield attitude.

[0029] When the longitudinal inclination angle of the shield is 0 - 3%, the inclination angle of the horizontal continuous belt conveyor can be set to 0 - 4%.

[0030] When the longitudinal inclination angle of the shield is greater than 3%, the inclination angle of the horizontal continuous belt conveyor is set to 2 - 6%.

[0031] S6. Design the collaborative working parameters of the belt conveyor:

[0032] According to the existing shield speed, shield equipment information, and muck physical parameters, predict the required collaborative conveying capacity of the belt conveyor unit, and determine the belt width (600, 800mm) and real - time belt speed (0 - 3.2m / s) of the belt conveyor. Monitor the muck transportation situation in real - time, and conduct speed - adjustment collaborative control of the continuous belt conveyor during the muck - discharging process by combining the discharging conditions of the muck temporary storage bin and the muck reprocessing bin.

[0033] According to the division results of the shield tunnel section, determine the storage length of the horizontal continuous belt conveyor (400, 500, 600 m), and at the same time determine the vulcanization connection spacing of the horizontal continuous belt conveyor (for every 200, 250, 300 m of shield equipment tunneling);

[0034] S7. Set up early warning for the failure state of muck transportation and self - response plan;

[0035] According to the detection data in the muck temporary storage bin, if the particle size of the transported material is between 0 - 80 mm and the rough internal friction angle obtained by cross - shear at different depths is less than 20°, or the appearance characteristics of the muck shown in the image at the outlet of the temporary storage bin are in a slurry state and water seepage occurs, it is considered that the fluidity of the muck is poor and the belt conveyor is in an adhesion early warning state. At this time, the adhesion treatment equipment records and tracks this batch of soil samples, and removes the adhesion on the lower belt after it completes the muck discharging work;

[0036] If the particle size of the material is between 180 - 400 mm, and the appearance characteristics of the muck shown in the image at the outlet of the temporary storage bin are loose or the water - soil separation is serious, it is considered that the muck is in a slipping early warning state. At this time, the dynamic inclination angle of the horizontal continuous belt conveyor for this batch of muck should be less than 4% and continuous monitoring should be carried out. For the section where requirements are made for the muck lifting height, a vertical belt conveyor can be set at the tail of the horizontal belt conveyor for segmented lifting treatment;

[0037] S8. Determine key shield parameters such as thrust, torque, tunneling speed, cutter head rotation speed, etc., and make real - time adjustments under intelligent algorithms according to the groundwater abundance - rock mass reliability - fracture development degree in the front 0 - 50 m obtained and combined with the information in the geological exploration report;

[0038] When the distance between adjacent formation characteristic layers in the shield tunnel section is mostly more than 100 m and the section settlement requirement is loose, parameter control can be carried out according to mudstone, sandstone, and composite sand - mudstone;

[0039] Mudstone: The tunneling rate is 45 - 60 mm / min, the tunneling cutter head torque is 65% - 80% of the rated torque, and the cutter head rotation speed is 1.5 - 2.8 r / min;

[0040] Sandstone: The tunneling rate is 40 - 50 mm / min, the tunneling cutter head torque is 75% - 90% of the rated torque, and the cutter head rotation speed is 2.3 - 3 r / min;

[0041] Composite sand - mudstone: The tunneling rate is 40 - 50 mm / min, the tunneling cutter head torque is 70% - 80% of the rated torque, and the cutter head rotation speed is 2.3 - 3 r / min;

[0042] In the shield section, the formation characteristics are complex, with thin interlayers and interbedded layers frequently appearing, or the advanced detection results showing highly developed fissures and strong weathering characteristics in the front area. In such cases, it is necessary to make full use of means such as advanced grouting and overexcavation to reduce surface settlement and prevent the shield from deviating. At the same time, adjust the shield parameters for the poor sandy mudstone interbedded layer: the tunneling speed is 30 - 45 mm / min, the torque of the tunneling cutterhead is 70% - 80% of the rated torque, and the cutterhead rotation speed is 2.4 - 3.2 r / min.

[0043] In addition, the rolling angle of the cutterhead is controlled within ±20°. When the rolling angle exceeds the limit, immediately switch the cutterhead rotation direction.

[0044] S9. Based on the key shield parameters, select the appropriate synchronous grouting slurry for the sandy mudstone interbedded layer:

[0045] Final setting time: Generally, it is 2 - 4 h. According to the formation conditions and tunneling speed, adjust the gel time by adding accelerators and changing the ratio through on-site tests. For highly permeable formation conditions and sections where higher early strength is required for grouting, adjust the ratio and add early strength agents through on-site tests to further shorten the gel time, obtain early strength, and ensure the grouting effect.

[0046] Strength of the consolidated body: Not less than 0.3 MPa in one day (slightly higher than the unconfined compressive strength of soft rock), and not less than 3 MPa in 28 days (slightly greater than the natural compressive strength of strongly weathered rock). Slurry stone formation rate: 95%, that is, the consolidation shrinkage rate < 5%. Slurry consistency: 12 ± 2 cm. Slurry stability: Inclination rate (the ratio of the volume of floating water to the total volume after static precipitation) is less than 5%.

[0047] During construction, strengthen the daily monitoring of the mud performance indicators. When it is found that the mud performance exceeds the set indicators, immediately carry out waste mud treatment to ensure that the mud performance meets the construction requirements of the sandy mudstone interbedded layer.

[0048] S10. Based on the gel time and grouting parameters, coordinate with the shield speed to establish a rapid shield settlement control material plan for the sandy mudstone interbedded layer and carry out synchronous grouting;

[0049] When the shield speed is 25 - 35 mm / min, the injection rate is taken as 1.2 - 1.3, the grouting pressure is the static water and soil pressure + 0.15 - 0.2, and the final setting time of the slurry is 3 - 4 h;

[0050] When the shield speed is 35 - 50 mm / min, the injection rate is taken as 1.3 - 1.4, the grouting pressure is the static water and soil pressure + 0.2 - 0.25, and the final setting time of the slurry is 2.5 - 3 h;

[0051] When the shield speed is 50 - 60 mm / min, the injection rate is taken as 1.4 - 1.55, the grouting pressure is the static water and soil pressure + 0.25 - 0.35, and the final setting time of the slurry is 2 - 2.5 h;

[0052] S11. Check and revise the scheme at the first 2-8 rings of the shield machine, set up a fast shield settlement monitoring system and perform settlement maintenance;

[0053] The horizontal attitude is controlled within ±20mm, and the vertical attitude is judged as -40--20mm according to the floating situation of the pipe segment. When the attitude exceeds the control range, the attitude must be corrected in time. The horizontal attitude correction shall not exceed 6mm per ring, and the vertical attitude correction shall not exceed 4mm per ring.

[0054] The surveying team shall re-measure the formed tunnel segments in time according to the requirements of the specification. When the floating amount is found to exceed 40mm, the 4-6 ring segments behind the shield tail shall be re-grouted in time. The secondary grouting shall be carried out with cement slurry, and double slurry shall be used when necessary. The grouting pressure shall be controlled between 0.3-0.5MPa. The grouting amount can be adjusted at any time according to the management level and the actual situation on site to control the floating of the segments. Among them, the double liquid slurry shall use water glass with a modulus of 2.4-2.8 and a Baume degree of about 39-48; the cement slurry / water glass slurry value shall be 1:0.7-1; the water-cement ratio of the single liquid slurry shall be 0.6-0.9, and the early strength agent or other external penetration agent may be added; the grouting outlet pressure shall be 0.1MPa-0.2MPa greater than the static water and soil pressure at the grouting outlet, and controlled at 0.3-0.5MPa.

[0055] The aforementioned sand-mudstone interlayer belt coordinated shield rapid shield construction method is characterized in that: wherein, the air pressure array driven hammer source feedback-fiber demodulation advance detection described in step S1 includes a circumferential hammer source system, an analytical device, a fiber demodulation system, a signal relay system, and a three-component sensor. Five source systems are arranged in the middle of the upper, lower, left, and right parts of the shield machine, drilling positioning and construction, pneumatic hammer source base welding, source system core device installation, source system shield body internal fixation, and source control system connection; preferably, a shield air pressure of 0.6-0.8MPa is used for hammer source excitation.

[0056] The specific implementation steps are as follows: ① Check the connection status between the wireless control module of the pneumatic seismic source and the host control software; ② Check whether the air pressure displayed on the shield machine air compressor is normal. Generally speaking, the air pressure can be greater than 0.5MPa, and open the valve to keep the main air inlet of the pneumatic seismic source connected to the air outlet of the air compressor; ③ Use electromagnetic wave signals to send instructions to the wireless control device, wait for the equipment to complete energy storage, and drive the seismic source excitation device to hammer the surrounding rock through the internal solenoid valve of the wireless control device; ④ Use the position recovery module to retract the hammer rod to the seismic source excitation device to complete the elastic wave excitation; ⑤ Receive the signal through the sensor, transfer the signal through the relay system, and use the optical fiber and computer system to demodulate and analyze the signal to complete the advanced detection and analysis.

[0057] The above-mentioned rapid shield construction method for sandstone-mudstone interbedded belt cooperative shield is characterized in that: in step S1, when the sandstone-mudstone interbed shows any of the following characteristics, it is considered unsuitable for setting a working shaft or as a section division point: ① The joints of the rock strata around the tunnel are developed, the crack length is greater than 3m, and the spacing is 0.2-0.4m; ② The thickness ratio of the sandstone-mudstone layer is less than 2:1, there are interbedded layers in a disorderly manner, sandy mudstone interbedded with thin sandstone layers, or the rock strata at the shield face show strongly weathered characteristics; ③ There is a complex soft stratum that is difficult to control from the tunnel top to the ground surface, and there is a high water pressure of more than 0.5MPa.

[0058] The above-mentioned rapid shield construction method for sandstone-mudstone interbedded belt cooperative shield is characterized in that: in step S2, in the double-mode shield method, the soil slag generated in the earth pressure mode is output to the muck distributor by the screw conveyor, and the muck distributor with two-way transmission transports the muck to the muck temporary storage bin and the muck reprocessing bin, and drainage devices are respectively arranged in the two bins to separate the excess water of the muck; in the slurry shield stage, the slurry is discharged by the slurry pump, and the muck stones, mud materials, and crushed materials broken out are screened and discharged into the muck treatment bin. After the muck treatment bin drains and crushes the muck inside, the muck is collected in the muck temporary storage bin; when the sensor in the muck temporary storage bin detects that the temporary storage capacity reaches 60% of the total capacity, the muck temporary storage bin discharges the muck in batches, and the belt unit starts to transport the muck.

[0059] The above-mentioned rapid shield construction method for sandstone-mudstone interbedded belt cooperative shield is characterized in that: in step S3, the bandwidth of the muck distributor adopts the same parameters as the continuous horizontal belt conveyor; at the same time, a hydraulic roller is used to drive the belt to realize forward and reverse transportation and stepless speed change.

[0060] The above-mentioned rapid shield construction method for sandstone-mudstone interbedded belt cooperative shield is characterized in that: in step S3, image monitoring equipment is set at the screw muck outlet and the muck outlet of the temporary storage bin to collect and screen the muck morphology images. Preferably, through mechanical training techniques such as training and optimizing convolutional neural network models, BP network models, and Monte Carlo, automatic classification and feature recognition of muck characteristics are realized according to information such as color, texture, shape, and surface smoothness, forming a muck image recognition technology.

[0061] The aforesaid rapid shield construction method for sandstone-mudstone interbedded belt collaborative shield is characterized in that: the horizontal continuous belt conveyor support in step S3 includes components such as upper and lower idler groups, side guard roller supports, cross beams, and tunnel supports; the upper and lower idler groups are fixed to the cross beam by bolts. The cross beam is an extendable structure, with a group of 50 - 60 m, fixed to the tunnel segment by a lifting connecting rod, and a small-angle rotation within the range of 0 - 2° can be achieved through a lifting rod to realize the change of the dynamic inclination angle. When the belt conveyor passes through the horizontal straight section, the spacing between the upper idler groups is 1.2 - 1.6 m, the spacing between the lower idler groups is 2.4 - 3.2 m, and one group of side guard rollers (with discs at the top) is arranged every 16 - 20 m. The cross beam is made of I-beam or channel steel, with a length of 2.6 - 3.0 m; when the belt conveyor passes through the horizontal turning section, the spacing between the upper idler groups is 0.8 - 1 m, the spacing between the lower idler groups is 1.2 - 1.6 m, and one group of side guard rollers (with discs at the top) is arranged every 4 - 5 m.

[0062] The aforesaid rapid shield construction method for sandstone-mudstone interbedded belt collaborative shield is characterized in that: in step S6, the shield speed (V, mm / s), excavation diameter (D, mm), muck density (ρ, g / mm 3 ), stacking coefficient of sandstone-mudstone interbeds (K, taking values from 1.3 - 1.8 from large to small according to the joint development state of sandstone and mudstone), complex transmission surplus coefficient (T, taking values of ρ + 0.1 to ρ + 0.25), and the maximum transmission capacity (Q, mm 3 / s) of the belt conveyor group are as follows:

[0063]

[0064] The aforesaid rapid shield construction method for sandstone-mudstone interbedded belt collaborative shield is characterized in that: in step S7, multiple sets of deviation preventing rollers and pull cord switches are arranged along the body of the conveyor system, a blockage monitoring device is set at the slag transfer and discharging places, a backstop is configured for the transmission mechanism, and multiple types of protection measures such as speed, over-temperature, power-off, and leakage protectors and audible and visual alarms are set for the drive control system to realize the dynamic monitoring of the conveyor system, record the operation data throughout the process, automatically stop the machine and give an alarm in case of abnormal conditions, and fully guarantee the safety of personnel and equipment.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] 1. The present invention adopts a pneumatic array-driven hammering seismic source feedback - fiber optic demodulation to achieve three-characteristic forward detection, and establishes a reliable shield section and route planning scheme in combination with the exploration report; provides a risk perception method for sandstone-mudstone interbedded shields, which can timely detect dangerous working conditions existing in the sandstone-mudstone interbeds, so as to take corresponding measures in time. Based on the detection results, the shield parameters, belt conveyor working parameters, and grouting parameters can be pre-acted in advance to ensure the safe and efficient development of shield tunneling, muck transportation, and grouting protection.

[0067] 2. By setting retractable splitting cones and advanced reinforcement devices on the shield cutter head surface, precise interruption and reinforcement of the outer edge of the surrounding rock and soil of the heading face are achieved, reducing the additional disturbance of the shield machine to the surrounding rock and soil in the sandstone-mudstone interlayer and decreasing the occurrence of local collapses and side wall or surrounding rock collapses. In addition, the present invention sets profiling overexcavation cutters, providing a highly feasible solution for quickly correcting the shield attitude deviation.

[0068] 3. A muck transportation and treatment solution is proposed. By setting a muck classifier to classify and store the muck, and setting a muck treatment bin and a muck temporary storage bin to collect, process, and detect the muck at the muck outlet, the characteristics of the treated muck are made more stable, solving the engineering problem of difficult improvement of muck with large differences in a short interval; through the drainage treatment of the muck, the muck transported on the conveyor belt has better fluidity, ensuring the stability and safety of transportation; setting muck soil mechanics property sampling and detection devices, and adjusting the transportation attitude and transmission rate of the belt conveyor according to the muck property information obtained by cross shear, etc., improving the coordination degree of muck excavation and transportation.

[0069] 4. The present invention designs an adaptation solution for a continuous belt conveyor under large horizontal turning angles. According to different horizontal turning angle grades, self-aligning rollers are used to apply a centrifugal inclination angle in the direction perpendicular to the belt, and the self-tensioning of belt transportation is achieved by utilizing the self-weight of the muck combined with a tension driving machine, effectively avoiding engineering problems such as belt deviation and slipping of the belt conveyor due to horizontal turning angles. In addition, the present invention considers the route slope and lifting height in combination with the monitoring of the belt conveyor transportation state. By setting a dynamic inclination angle for the belt conveyor and combining measures such as segmental heightening of the vertical belt conveyor, the occurrence of muck slipping is reduced, ensuring the shield construction environment.

[0070] 5. The present invention sets up an intelligent monitoring and early warning system for muck adhesion and slipping, arranges cleaners and high-pressure flushing equipment to complete the anti-adhesion operation of the belt conveyor; solves the problem of muck slipping by adjusting the extendable crossbeam to achieve dynamic inclination angle transportation of the belt conveyor. Thus, an autonomous response plan for early warning situations is formed, improving the intelligence of construction and reducing the manual maintenance cost; reducing the frequency of belt conveyor maintenance and shutdown repair, avoiding construction period delays caused thereby, and improving the reliability and stability of the muck transportation project.

[0071] 6. In view of the characteristics of the sandstone-mudstone interlayer, the present invention stipulates the applicability of the performance of the grouting material; based on the gelation time and grouting parameters in coordination with the shield speed, a grouting material and process plan for rapid shield settlement control in the sandstone-mudstone interlayer is established, and the plan is tested and corrected, thereby forming a technology for controlling settlement and deformation of rapid shield tunneling in the sandstone-mudstone interlayer. Solving the engineering problem of the forced slowdown of the tunneling speed due to the complex characteristics of the sandstone-mudstone interlayer. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 The figure shows the flow chart of the rapid shield construction method for the sandstone-mudstone interlayer belt collaborative shield of the present invention.

[0073] Figure 2 The figure shows the schematic diagram of the muck transportation plan for the belt conveyor collaborative shield of the present invention. Specific embodiments

[0074] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0075] Embodiment 1

[0076] Rapid tunneling construction method for the sandstone-mudstone interlayer belt collaborative shield in a certain section of Chongqing Rail Transit Line 15

[0077] S1. Obtain the geological shield section survey report as the original data, and lay out the shield advanced detection facilities; establish an advanced detection plan considering the mileage of the shield section and the formation differences between each section, delimit the shield segments and lay out the construction working wells:

[0078] ① Conduct the formation information collection work before shield tunneling to form a geological survey report: Taking a section of characteristic formation as an example, its rock layer sequence is normal, the dip is 85°-93°, and the dip angle is 5°-10°. In the plane, the dip angle is smaller near the syncline axis and larger away from the syncline axis; vertically, the surface dip angle is relatively gentle, and the dip angle of the deep rock layer gradually becomes steeper, and the bedding plane combination is very poor, which is a soft structural plane. There are mainly two groups of tectonic fissures developed in the rock layer: J1: The dip is 176-205°, the dip angle is 60-78°, the extension is 3-8m, slightly open 1-3mm, gentle wave-shaped, the spacing is 1-3m, locally filled with argillaceous, the combination is poor, and it belongs to a hard structural plane. J2: The dip is 83-115°, the dip angle is 70-85°, the extension is 2-8m, generally closed-slightly open, straight, the spacing is 2-3m, occasionally filled with argillaceous, the combination is poor, and it belongs to a hard structural plane.

[0079] The buried depth of the tunnel roof in this section is about 7.5-63m, the overlying rock thickness is 0-60m, and the rock layers passed through mainly include sandstone, sandy mudstone and plain fill, which belongs to the typical sandstone-mudstone interlayer geology. Most areas are characterized by medium weathering. The air pressure array-driven hammering seismic source feedback-fiber optic demodulation is used to realize the three-characteristic advanced detection of water, rock and fissures. The results show that the upper part of the formation passed through by the shield is mudstone and the lower part is sandstone, and there is an upper-soft-lower-hard formation.

[0080] ②Design the interval with the actual situation of the sandstone-mudstone interbed as the final decision-making condition. The total length of the shield interval is 2,900 m, and there are 3,212 rings of segments. This reduces non-advancing operations such as the starting, turning around, and transfer of the shield machine. According to the groundwater abundance-rock mass reliability-fracture development degree of 0 - 50 m ahead obtained and combined with the information in the geological exploration report, working shafts are set at continuously stable strata locations, and the construction spacing of the working shafts is 1.5 km; the depth of the starting shaft and the hoisting shaft is about 21 m, and a 15.0×9.5 m shield working shaft is reserved as the muck outlet and the normal tunneling material hoisting port.

[0081] Among them, the air pressure array-driven hammering vibration source feedback - fiber optic demodulation advanced detection includes a circumferential hammering vibration source system, an analysis device, a fiber optic demodulation system, a signal transfer system, and a three-component sensor. Five vibration source systems are arranged at the upper, lower, left, right, and middle parts of the shield machine, including drilling positioning and construction, welding of the pneumatic hammering vibration source base, installation of the core device of the vibration source system, fixing of the vibration source system inside the shield body, and connection of the vibration source control system; preferably, a shield air pressure of 0.6 MPa is used to excite the sandstone-mudstone interbed by the hammering vibration source.

[0082] The specific implementation steps are as follows: ① Detect the connection status of the pneumatic vibration source wireless control module and the host control software; ② Check whether the air pressure displayed by the shield machine air compressor is normal. Generally, the air pressure greater than 0.5 MPa is sufficient, and open the valve to keep the main air inlet of the pneumatic vibration source connected to the air outlet of the air compressor; ③ Send an instruction to the wireless control device using an electromagnetic wave signal, wait for the equipment to complete energy storage, and drive the vibration source excitation device to hammer the surrounding rock through the solenoid valve inside the wireless control device; ④ Retract the hammer rod into the vibration source excitation device through the setting and recovery module to complete the elastic wave excitation; ⑤ Receive signals through the sensor, transfer the signals by the transfer system, and use the fiber optic and computer system to demodulate and analyze the signals to complete the advanced detection analysis.

[0083] S2. Due to the influence of the geographical environment in Chongqing area, there are mostly hills and valleys, and the buried depth of the strata varies greatly, so the earth pressure on the shield machine will also change greatly. Determine the shield mode and cutterhead modification plan based on the characteristics of the sandstone-mudstone interbed:

[0084] ① In this embodiment, the distance between adjacent stratum characteristic layers on the tunneling route is mostly 100 m and above. When the geological data shows that the medium-weathered rock core is medium-long columnar, the fissures are not developed - relatively developed, the rock mass is relatively complete, the rock quality is relatively hard, and the groundwater level is relatively low, a compound earth pressure balance shield is adopted and a cutterhead modification plan is set to prevent the attitude deviation caused by rapid shield tunneling under uneven strata;

[0085] ③ Due to the huge change in the buried depth of the strata, once the strata become unstable (collapse phenomenon), it is very easy to cause the problem of shield jamming. For the shield tunneling in the sandstone-mudstone interbed, a reverse cutter seat is set on the spoke panel cutterhead to realize the orderly switching of the button cutters and the smooth wide-edge cutters;

[0086] ④Set a retractable splitting cone drill and a profiling overexcavation cutter to reduce the disturbance and settlement of the surrounding strata and provide measures for quickly correcting the shield attitude deviation, while facilitating the shield to get out of trouble. Configure a composite bentonite injection system and an advanced reinforcement device with sufficient capacity. Because of the excellent injection performance of bentonite, the resistance between the shield and the rock stratum can be effectively reduced.

[0087] S3. The maximum longitudinal slope is -44‰, with a large slope and a long distance; the horizontal transportation risk of the battery vehicle with heavy load is high, the efficiency is low, and the vehicle is prone to slipping. When using an 8m-class shield for construction, the excavation section is large, and the amount of slag removed per ring of tunneling is large. According to the construction experience of 6m-class shields in Chongqing, the loose slag is calculated at 1.5. The amount of slag discharged per ring of tunneling in this project is about 165m3. The project plans to use a continuous belt conveyor for slag transportation and a battery vehicle for segment, mortar and material transportation to reduce the horizontal transportation risk. The belt conveyor set used for shield slag transportation includes a slag distributor, a horizontal continuous belt conveyor, and a vertical belt conveyor. The soil slag generated under the earth pressure mode is output to the slag distributor through the screw conveyor. The slag distributor with two-way transmission transports the slag to the slag temporary storage bin and the slag reprocessing bin. Drainage devices are respectively set in the two bins to separate the excess water of the slag; the crushed slag stones, mud materials, and crushed materials are screened and discharged into the slag treatment bin. After the slag treatment bin drains and crushes the slag inside, the slag is collected in the slag temporary storage bin; when the sensor in the slag temporary storage bin detects that the temporary storage amount reaches 60% of the total capacity, the temporary storage bin discharges the slag in batches, and the belt conveyor set starts to transport the slag.

[0088] ①The slag distributor has two storage bins at the end, one slag temporary storage bin and one slag reprocessing bin; when the temporary storage bin and the treatment bin reach a certain volume, the soil is discharged centrally, and the slag is transferred to the horizontal continuous belt conveyor for long-distance horizontal transportation;

[0089] The horizontal continuous belt conveyor support includes components such as upper and lower idler groups, side roller supports, cross beams, and tunnel supports; the upper and lower idler groups are fixed to the cross beam with bolts. The cross beam is an extendable structure, with a group of 54m, fixed to the tunnel segment through a lifting link rod, and the cross beam can rotate at a small angle within the range of 0-2° through a lifting rod to achieve the change of the dynamic inclination angle. When the belt conveyor passes through the horizontal straight section, the spacing of the upper idler group is 1.4m, the spacing of the lower idler group is 2.8m, and the side rollers (with discs at the top) are arranged in groups of 1 every 18m. The cross beam is made of I-beam or channel steel with a length of 2.8m; when the belt conveyor passes through the horizontal turning section, the spacing of the upper idler group is 1m, the spacing of the lower idler group is 2m, and the side rollers (with discs at the top) are arranged in groups of 1 every 4m.

[0090] ②The tail of the reprocessing bin for muck is connected to the temporary storage bin for muck, enabling remixing after muck treatment. Inside the temporary storage bin for muck, there are portable mechanical soil extractors, cross-shearing devices, and rapid direct shear equipment. By combining image recognition, the soil characteristics of batches of soil can be detected (rough particle size of materials, internal friction angle, muck density, muck flow plasticity state). The muck image recognition technology involves setting image monitoring devices at the spiral muck outlet and the muck outlet of the temporary storage bin respectively to collect and screen muck morphology images. Through the mechanical training technology of training and optimizing the convolutional neural network model, automatic classification and feature recognition of muck characteristics are achieved based on information such as color, texture, shape, and surface smoothness.

[0091] ③On the back of the downward section of the belt, an active flapper cleaner and a scraper cleaner are respectively set, and multiple groups of high-pressure water flushing devices are set at the front end as adhesion treatment equipment;

[0092] ④The vertical belt conveyor is set at the end of the horizontal continuous belt conveyor or in the vertical working shaft, and is used for vertical transportation according to the height requirement of the muck. After the vertical belt conveyor transports the muck to its end, the muck drops into the muck pool for storage or treatment, and finally the muck discharging work is completed;

[0093] S4. Based on the shield route planning scheme, design the horizontal rotation angle of the continuous belt conveyor in coordination with the shield attitude; among them, the flat curve types include straight line, transition curve, and circular curve. Among them, the curve radius is 600 - 1500 m, and the section length is 112 - 678 m; the extreme sections A is a circular curve with a radius R = 1500 m and a length of 199.5 m, and B is a circular curve with a radius R = 600 m and a length of 659.4 m.

[0094] ①For the turning section with a flat circular curve radius greater than 1200 m, self-aligning rollers are used to apply a centrifugal inclination angle of 2 - 8° in the direction of the vertical belt;

[0095] ②For the turning section with a flat circular curve radius of 400 - 1200 m, self-aligning rollers are used to apply a centrifugal inclination angle of 5 - 10°, and by utilizing the self-weight of the muck combined with the tension drive, self-tensioning of the belt transportation is achieved;

[0096] S5. The shield machine line in this section starts from Station X with a downhill slope of -2‰, and then goes downhill with -43.323‰ and -5.3‰, and uphill with 12.584‰, 37.26‰, and 2‰ to access Station Y; the left line starts from Station X with a downhill slope of -2‰, and then goes downhill with -44.044‰ and 5.3‰, and uphill with 12.5‰, 37.26‰, and 2‰ to access Station Y; the required muck lifting height is 25 m. Considering the slope angle and lifting height requirements on the shield route, design the vertical inclination angle of the continuous belt conveyor in coordination with the shield attitude;

[0097] ①When the longitudinal slope inclination angle of the shield is 0 - 3%, the inclination angle of the horizontal continuous belt conveyor can be set to 0 - 4%;

[0098] ② When the longitudinal gradient inclination angle of the shield is greater than 3%, the inclination angle of the horizontal continuous belt conveyor is set to 2-6%.

[0099] S6. The total muck output of the shield section in this embodiment is 354,067 m³ (in-situ volume), and the designed collaborative working parameters of the belt conveyor are as follows:

[0100] ① According to the existing tunneling rate, shield diameter size, and physical parameters of the muck, predict the required collaborative conveying capacity of the belt conveyor unit, and determine the belt width of the belt conveyor to be 800 mm and the real-time belt speed of the belt conveyor (0-3.2 m / s); the belt width of the muck distributor is adopted with the same parameters as the continuous horizontal belt conveyor; at the same time, use a hydraulic roller to drive the belt to achieve forward and reverse transportation and stepless speed change.

[0101] ② Monitor the muck transportation situation in real time, and combine the discharging conditions of the muck temporary storage bin and the muck treatment bin to carry out speed regulation and collaborative control of the continuous belt conveyor during the muck excavation process;

[0102] ③ According to the division results of the shield section, determine the storage belt length of the horizontal continuous belt conveyor to be 500 mm, and at the same time determine the vulcanization connection spacing of the horizontal continuous belt conveyor. The shield equipment advances 250 mm each time;

[0103] S7. In this shield section, a warning for the failure state of muck transportation and a self-response plan are set for muck particle sizes of 0-300 mm;

[0104] ① According to the detection data in the muck temporary storage bin, if the particle size of the transported material is between 0-80 mm and the rough internal friction angle obtained by cross shear at different depths is less than 20°, or the muck appearance characteristics shown in the image at the outlet of the temporary storage bin are in a slurry state and water seepage occurs, it is considered that the muck has poor fluidity and the belt conveyor is in an adhesion warning state. At this time, the adhesion treatment equipment records and tracks this batch of soil samples, and removes the adhesion on the lower belt after its muck excavation work is completed;

[0105] ② If the particle size of the material is between 180-300 mm, and the muck appearance characteristics shown in the image at the outlet of the temporary storage bin are loose or the water and soil separation is serious, it is considered that the muck is in a sliding warning state. At this time, the dynamic inclination angle of the horizontal continuous belt conveyor for this batch of muck should be less than 4% and continuous monitoring should be carried out. For the sections with requirements for the muck lifting height, a vertical belt conveyor can be set at the tail of the horizontal belt conveyor for segmented lifting treatment;

[0106] The conveyor system is provided with multiple sets of deviation prevention rollers, pull cord switches along the fuselage, blockage monitoring devices are set at the muck transfer and discharging places, a backstop is configured for the transmission mechanism, and speed, over-temperature, power-off, leakage protection devices, audible and visual alarms and other types of protection measures are set for the drive control system to realize dynamic monitoring of the conveying system, record the operation data throughout the process, and the abnormal conditions can automatically stop the machine and alarm, fully ensuring the safety of personnel and equipment.

[0107] S8. Determine key shield parameters such as thrust, torque, tunneling speed, cutterhead rotation speed, etc., and based on the water abundance - rock mass reliability - fracture development degree of the front 0 - 50m obtained and combined with the information in the geological exploration report, perform real - time adjustment under intelligent algorithms;

[0108] (1) When the distance between adjacent formation characteristic layers in the shield section is mostly above 100m and the settlement requirement of the section is loose, parameter control can be carried out according to mudstone, sandstone, and composite sand - mudstone;

[0109] ① Mudstone: The tunneling rate is 45 - 60mm / min, the tunneling cutterhead torque is 65% - 80% of the rated torque, and the cutterhead rotation speed is 1.5 - 2.8r / min;

[0110] ② Sandstone: The tunneling rate is 40 - 50mm / min, the tunneling cutterhead torque is 75% - 90% of the rated torque, and the cutterhead rotation speed is 2.3 - 3r / min;

[0111] ③ Composite sand - mudstone: The tunneling rate is 40 - 50mm / min, the tunneling cutterhead torque is 70% - 80% of the rated torque, and the cutterhead rotation speed is 2.3 - 3r / min;

[0112] (2) When the formation characteristics in the shield section are complex, thin interlayers and interbedded layers appear frequently, or the advanced detection results show that the fissures in the front area are highly developed and have strong weathering characteristics, it is necessary to make full use of means such as advanced grouting and over - excavation to reduce surface settlement and reduce shield deviation. At the same time, adjust the shield parameters for the bad sand - mudstone interlayer: the tunneling rate is 30 - 45mm / min, the tunneling cutterhead torque is 70% - 80% of the rated torque, and the cutterhead rotation speed is 2.4 - 3.2r / min;

[0113] In addition, the cutterhead rolling angle is controlled within ±20°. When the rolling angle exceeds the limit, immediately switch the cutterhead rotation direction.

[0114] S9. Based on the adopted shield key parameters, select the appropriate type of synchronous grouting slurry for the sand - mudstone interlayer:

[0115] ① Final setting time: According to the formation conditions and tunneling speed, it is generally 2 - 4h. The setting time is adjusted by adding accelerators and changing the ratio through on - site tests. For strongly permeable formation conditions and sections that require grouting to provide higher early strength, the ratio is adjusted and early - strength agents are added through on - site tests to further shorten the setting time, obtain early strength, and ensure the grouting effect.

[0116] ② Consolidated body strength: Not less than 0.3MPa in one day (slightly higher than the unconfined compressive strength of soft rock strata), and not less than 3MPa in 28d (slightly greater than the natural compressive strength of strongly weathered rock).

[0117] ③ Slurry stone formation rate: 95%, i.e., the consolidation shrinkage rate < 5%.

[0118] ④ Slurry consistency: 12 ± 2 cm.

[0119] ⑤ Slurry stability: Inclination rate (the ratio of the volume of floating water to the total volume after static precipitation) is less than 5%.

[0120] The mixing ratio of the synchronous grouting material used in this embodiment is as shown in the table:

[0121]

[0122] During construction, strengthen the daily monitoring of the slurry performance indicators. When it is found that the slurry performance exceeds the set indicators, waste slurry treatment shall be carried out immediately to ensure that the slurry performance meets the construction requirements of the interbedded sandstone and mudstone.

[0123] S10. In the shield section, the total synchronous grouting volume is 38956 m 3 (The grouting coefficient is about 1.5). Based on the setting time and grouting parameters, coordinate with the shield speed to establish a rapid shield settlement control material plan for the interbedded sandstone and mudstone.

[0124] (1) Mixing and transportation of slurry

[0125] The slurry is mixed well at the mixing station. All kinds of materials are metered by an automatic metering device. The mixing time of each batch of materials should meet the requirements of the specification, and all kinds of aggregates should be fully mixed evenly.

[0126] The slurry is transported to the construction site by a tank truck and put into the storage tank. After the slurry is stirred evenly in the tank, it is put into the mortar truck at the bottom of the well. The battery car drags the mortar train car to the storage tank of the trailer in the tunnel, and the slurry in the mortar truck is pumped into the storage tank in the trailer by a mortar pump.

[0127] (2) Grouting time and speed

[0128] In different strata, the length of the grouting time is specifically controlled according to the slurry with different setting times and the tunneling speed. Achieve "simultaneous tunneling and grouting, no tunneling without grouting", and determine the grouting time by controlling the double standards of synchronous grouting pressure and grouting volume. Stop grouting only after the grouting volume and grouting pressure reach the set values, otherwise additional grouting is still required.

[0129] The synchronous grouting speed is matched with the tunneling speed, and the average grouting speed is determined according to the completion of the grouting volume of the current ring within the time when the shield completes one ring of tunneling. For the grouting end standard and the inspection of the grouting effect, a double-index control standard of grouting pressure and grouting volume is adopted, that is, when the grouting pressure reaches the set value, it can be considered that the quality requirements are met.

[0130] (3) Main technical parameters of synchronous grouting:

[0131] ① When the shield speed is 25-35mm / min, the injection rate is 1.2-1.3, the grouting pressure is static water and soil pressure + 0.15-0.2, and the final setting time of the slurry is 3-4h;

[0132] ② When the shield speed is 35-50mm / min, the injection rate is 1.3-1.4, the grouting pressure is static water and soil pressure + 0.2-0.25, and the final setting time of the slurry is 2.5-3h;

[0133] ③ When the shield speed is 50-60mm / min, the injection rate is 1.4-1.55, the grouting pressure is static water and soil pressure + 0.25-0.35, and the final setting time of the slurry is 2-2.5h;

[0134] (4) Slurry end standard and effect inspection

[0135] Synchronous grouting is comprehensively evaluated with dual control indicators of grouting volume and grouting pressure, that is, when the grouting pressure reaches the set value and the grouting volume reaches more than 85% of the design value, it can be considered that the quality requirements have been met. During the excavation process, the grouting standards are optimized and corrected through ground settlement monitoring data, shield tail leakage, pipe segment floating, etc. The grouting effect inspection mainly adopts the analytical method, that is, according to the PQt curve, combined with the excavation speed and the deformation measurement results of the lining and surrounding buildings on the surface, a comprehensive analysis and judgment is made. If necessary, non-destructive detection methods are used to inspect the effect.

[0136] S11: This section passes through underground passages, rivers, roadbeds, etc., and passes through facilities or landforms such as overpasses and road bridges. The scheme is checked and corrected at the first 2-8 rings of the shield tunneling. A rapid shield tunneling settlement monitoring system is set up and settlement maintenance is carried out.

[0137] ① The horizontal attitude is controlled within ±20mm, and the vertical attitude is judged as -40--20mm according to the floating situation of the pipe segment. When the attitude exceeds the control range, the attitude must be corrected in time. The horizontal attitude correction shall not exceed 6mm per ring, and the vertical attitude correction shall not exceed 4mm per ring.

[0138] ② The measurement team shall re-measure the formed tunnel segments in time according to the requirements of the specification. When the floating amount is found to exceed 40mm, the 4-6 ring segments behind the shield tail shall be re-grouted in time. The secondary grouting shall be carried out with cement slurry, and double slurry shall be used when necessary. The grouting pressure shall be controlled between 0.3-0.5MPa. The grouting volume can be adjusted at any time according to the management level and the actual situation on site to control the floating of the segments; among them, the double liquid slurry adopts a modulus of 2.5 and a Baume degree of 42 water glass; the cement slurry / water glass slurry value should be 1:0.8; the water-cement ratio of the single liquid slurry is 0.6, and the early strength agent or other external infiltration agent can be added; the grouting outlet pressure shall be greater than the static water and soil pressure at the grouting outlet by 0.2MPa, and controlled at 0.5MPa.

Claims

1. A rapid shield construction method for interbedded sandstone and mudstone belts with belt cooperation shield, characterized in that Including the following steps: S1. Obtain the geological shield section survey report as the original data and deploy shield advanced detection facilities; establish an advanced detection plan considering the mileage of the shield section and the formation differences between sections, delimit the shield segments and deploy construction working wells: ① Conduct the formation information collection work before shield tunneling to form a geological survey report; for the interbedded sandstone and mudstone formation, adopt the air pressure array-driven hammering vibration source feedback - fiber optic demodulation to achieve the three-characteristic advanced detection of water, rock, and fissures; ② Take the actual situation of the interbedded sandstone and mudstone as the final decision-making condition, control the mileage of urban rail sections within 3 - 8 km, and control the mileage of sections crossing rivers and lakes within 5 - 10 km; thus reducing the non-advancing operations such as the starting, turning around, and transferring of the shield machine; according to the groundwater abundance - rock mass reliability - fracture development degree of 0 - 50 m ahead obtained and combined with the information in the geological exploration report, set up working wells at continuous and stable formations, and the construction spacing of working wells is 1.5 km - 3.5 km; S2. Determine the shield mode and cutterhead modification plan according to the characteristics of the interbedded sandstone and mudstone: ① If the distance between adjacent formation characteristic layers on the tunneling route is mostly 100 m or more, and the geological data shows that the moderately weathered rock cores are medium - long columnar, the fissures are not developed - moderately developed, the rock mass is relatively complete, the rock quality is relatively hard, and the groundwater level is relatively low, adopt the earth pressure - slurry double - mode shield or earth pressure balance shield and set up a cutterhead modification plan to prevent the attitude deviation caused by rapid shield tunneling under uneven formations; ② If the distance between adjacent formation characteristic layers is concentrated below 100 m, or the sandstone and mudstone have strong weathering characteristics, or the mileage of the shield section with soft - upper - hard - lower, mudstone intercalated with thin sandstone, or sandstone intercalated with mudstone exceeds 60%, then adopt the earth pressure - slurry double - mode shield with partial slurry wall protection or the slurry shield mode for this section; ③ For the shield tunneling of the interbedded sandstone and mudstone, set up a reverse tool holder on the spoke - type cutterhead to realize the orderly switching of button cutters and smooth - faced wide - edge cutters; ④ Set up a retractable splitting cone drill, an advanced reinforcement device, and a profiling over - excavation cutter to provide a rapid rectification measure for the shield attitude deviation while reducing the disturbance and settlement of the surrounding formation; S3. Determine the belt conveyor muck transportation plan: The belt conveyor group used for shield muck transportation includes a muck distributor, a horizontal continuous belt conveyor, and a vertical belt conveyor; ① For the muck distributor, two storage bins, one muck temporary storage bin, and one muck re - treatment bin are set at the end; when the muck temporary storage bin and the muck re - treatment bin reach a certain volume, centralized soil discharging is carried out, and the muck is transferred to the horizontal continuous belt conveyor for long - distance horizontal transportation; ② The tail of the muck re - treatment bin is connected to the muck temporary storage bin to realize the re - mixing of muck after treatment; a portable mechanical soil sampler, a cross - shear device, and a rapid direct - shear device are arranged inside the muck temporary storage bin, and the soil properties of batches of soil can be detected by combining image recognition, including the rough particle size of the material, the internal friction angle, the muck density, and the muck fluidity state; ③ Active flapping cleaners and scraper cleaners are respectively set on the back of the downward section of the belt, and multiple groups of high - pressure water flushing devices are set at the front end as adhesion treatment equipment; ④The vertical belt conveyor is installed at the end of the horizontal continuous belt conveyor or in the vertical working shaft, and is used for vertical transportation according to the height requirement of the muck. When the vertical belt conveyor transports the muck to its end, the muck drops into the muck pool for storage or treatment, and finally the mucking work is completed; S4. Based on the shield route planning scheme, design the horizontal turning angle of the continuous belt conveyor in coordination with the shield attitude; ①In the turning section with a flat circular curve radius greater than 1200 m, self-aligning rollers are used, and a centrifugal inclination angle of 2-8° is applied in the direction of the vertical belt; ②In the turning section with a flat circular curve radius of 400-1200 m, self-aligning rollers are used and a centrifugal inclination angle of 5-10° is applied. By utilizing the self-weight of the muck and the tension driving machine, self-tensioning of the belt transportation is achieved; S5. Considering the slope angle and lifting height requirements on the shield route, design the vertical inclination angle of the continuous belt conveyor in coordination with the shield attitude; ①When the longitudinal slope inclination angle of the shield is 0-3%, the inclination angle of the horizontal continuous belt conveyor is set to 0-4%; ②When the longitudinal slope inclination angle of the shield is greater than 3%, the inclination angle of the horizontal continuous belt conveyor is set to 2-6%; S6. Based on the existing tunneling rate, shield diameter size, muck density, and muck loose coefficient, design the collaborative working parameters of the belt conveyor: ①Predict the collaborative conveying capacity required by the belt conveyor unit, determine the belt width, the belt width is 600 mm or 800 mm, and the real-time belt speed of the belt conveyor, the belt speed is 0-3.2 m / s; ②Monitor the muck transportation situation in real time, and conduct speed regulation and collaborative control of the continuous belt conveyor during the mucking process in combination with the discharging conditions of the muck temporary storage bin and the muck reprocessing bin; ③According to the shield section division result, determine the storage belt length of the horizontal continuous belt conveyor, the storage belt length is 400 m or 500 m or 600 m, and at the same time determine the vulcanization connection spacing of the horizontal continuous belt conveyor, the vulcanization connection spacing is that the shield equipment advances 200 m or 250 m or 300 m per tunneling; S7. Set up an early warning for the failure state of muck transportation and a self-response plan; ①According to the detection data shown in the muck temporary storage bin, if the particle size of the transported material is between 0-80 mm and the rough internal friction angle obtained by cross-shearing at different depths is less than 20°, or the image at the outlet of the temporary storage bin shows that the appearance characteristics of the muck are muddy and there is water seepage, it is considered that the muck has poor fluidity and the belt conveyor is in an adhesion early warning state. At this time, the adhesion treatment equipment records and tracks this batch of soil samples, and removes the adhesion on the lower belt after its mucking work is completed; ②If the particle size of the material is between 180-400 mm, and the image at the outlet of the temporary storage bin shows that the appearance characteristics of the muck are loose or the water and soil separation is serious, it is considered that the muck is in a slipping early warning state. At this time, make the dynamic inclination angle of the horizontal continuous belt conveyor for this batch of muck less than 4% and conduct continuous monitoring. For the section with requirements for the muck lifting height, a vertical belt conveyor is set at the tail of the horizontal belt conveyor for segmented lifting treatment; S8. Determine the key shield parameters such as thrust, torque, tunneling speed, and cutter head speed, and make real-time adjustments under the intelligent algorithm according to the groundwater abundance - rock mass reliability - fracture development degree of 0-50 m ahead obtained and the information in the geological exploration report; (1)When the distance between adjacent formation characteristic layers in the shield section is mostly above 100 m and the settlement requirement of the section is loose, parameter control is carried out according to mudstone, sandstone, and composite sand-mudstone; ① Mudstone: The tunneling rate is 45 - 60 mm / min, the torque of the tunneling cutterhead is 65% - 80% of the rated torque, and the cutterhead rotation speed is 1.5 - 2.8 r / min; ② Sandstone: The tunneling rate is 40 - 50 mm / min, the torque of the tunneling cutterhead is 75% - 90% of the rated torque, and the cutterhead rotation speed is 2.3 - 3 r / min; ③ Composite sand-mudstone: The tunneling rate is 40 - 50 mm / min, the torque of the tunneling cutterhead is 70% - 80% of the rated torque, and the cutterhead rotation speed is 2.3 - 3 r / min; (2)When the formation characteristics in the shield section are complex, thin interlayers and interbedded interlayers frequently appear, or the advanced detection results show that the fissures in the front area are highly developed and have strong weathering characteristics, it is necessary to make full use of advanced grouting and overexcavation means to reduce surface settlement and reduce shield deviation. At the same time, adjust the shield parameters for the poor sand-mudstone interlayer: the tunneling rate is 30 - 45 mm / min, the torque of the tunneling cutterhead is 70% - 80% of the rated torque, and the cutterhead rotation speed is 2.4 - 3.2 r / min; In addition, the rolling angle of the cutterhead is controlled within ±20°. When the rolling angle exceeds the limit, immediately switch the cutterhead rotation direction; S9. According to the key shield parameters adopted, conduct compatibility selection for the synchronous grouting slurry of the sand-mudstone interlayer: ① Final setting time: According to the formation conditions and tunneling speed, it is 2 - 4 h. Adjust the gel time by adding accelerators and changing the ratio through on-site tests; For strongly permeable formation conditions and sections that require grouting to provide high early strength, adjust the ratio and add early strength agents through on-site tests to further shorten the setting time, obtain early strength, and ensure the grouting effect; ② Strength of the consolidated body: Not less than 0.3 MPa in one day and not less than 3 MPa in 28 days; ③ Slurry stone formation rate: 95%, that is, the consolidation shrinkage rate < 5%; ④ Slurry consistency: 12 ± 2 cm; ⑤ Slurry stability: The inclination rate or the ratio of the volume of floating water after standing precipitation to the total volume is less than 5%; Strengthen the daily monitoring of the slurry performance indicators during construction. When it is found that the slurry performance exceeds the set indicators, it is necessary to immediately carry out waste slurry treatment to ensure that the slurry performance meets the construction requirements of the sand-mudstone interlayer; S10. Based on the setting time and grouting parameters, coordinate with the shield speed to establish a rapid shield settlement control material plan for the sand-mudstone interlayer and conduct synchronous grouting; ① When the shield speed is 25 - 35 mm / min, the injection rate is taken as 1.2 - 1.3, the grouting pressure is the static water and soil pressure + 0.15 - 0.2 MPa, and the final setting time of the slurry is 3 - 4 h; ② When the shield speed is 35 - 50 mm / min, the injection rate is taken as 1.3 - 1.4, the grouting pressure is the static water and soil pressure + 0.2 - 0.25 MPa, and the final setting time of the slurry is 2.5 - 3 h; ③ When the shield speed is 50-60 mm / min, the injection rate is 1.4-1.55, the grouting pressure is static water and soil pressure + 0.25-0.35 MPa, and the final setting time of the slurry is 2-2.5 h; S11. Check and revise the scheme at the first 2-8 rings of the shield machine, set up a fast shield settlement monitoring system and perform settlement maintenance; ① The horizontal attitude is controlled within ±20 mm, and the vertical attitude is judged as -40--20 mm according to the floating situation of the pipe segment. When the attitude exceeds the control range, the attitude correction must be carried out in time. The horizontal attitude correction shall not exceed 6 mm per ring, and the vertical attitude correction shall not exceed 4 mm per ring; The surveying team shall re-measure the formed tunnel segments in time according to the requirements of the specifications. When it is found that the floating amount exceeds 40 mm, the secondary grouting operation shall be carried out on the 4-6 ring segments behind the shield tail in time. Cement slurry shall be used for the secondary grouting, and double grouting shall be used when necessary. The grouting pressure shall be controlled between 0.3-0.5 MPa. The grouting volume shall be adjusted at any time according to the management level and the actual situation on site to control the floating of the segments. Among them, the double liquid slurry should adopt water glass with a modulus of 2.4-2.8 and a Baume degree of 39-48. The cement slurry / water glass slurry value should be 1:0.7-1. The water-cement ratio of the single liquid slurry is 0.6-0.9, and an early strength agent or other external penetration agent is added. The grouting outlet pressure should be 0.1-0.2 MPa greater than the static water and soil pressure at the grouting outlet and controlled at 0.3-0.5 MPa.

2. The sand-mudstone interlayer belt coordinated shield rapid shield construction method according to claim 1 is characterized by: (1) The air pressure array driven hammer source feedback-fiber demodulation advance detection described in step S1 includes a circumferential hammer source system, an analytical device, a fiber demodulation system, a signal relay system, and a three-component sensor; five source systems are arranged in the upper, lower, left, right, and middle parts of the shield machine, drilling positioning and construction, pneumatic hammer source base welding, source system core device installation, source system shield body internal fixation, and source control system connection; a shield air pressure of 0.6-0.8 MPa is used for hammer source excitation; (2) The specific implementation steps are as follows: ① Check the connection status between the wireless control module of the pneumatic seismic source and the host control software; ② Check whether the air pressure displayed by the shield machine air compressor is greater than 0.5 MPa, and open the valve to keep the main air inlet of the pneumatic seismic source connected to the air outlet of the air compressor; ③ Use electromagnetic wave signals to send instructions to the wireless control device, wait for the equipment to complete energy storage, and drive the seismic source excitation device to hammer the surrounding rock through the internal solenoid valve of the wireless control device; ④ Use the position recovery module to retract the hammer rod to retract the seismic source excitation device to complete the elastic wave excitation; ⑤ Receive the signal through the sensor, transfer the signal through the relay system, and use the optical fiber and computer system to demodulate and analyze the signal to complete the advanced detection and analysis.

3. The rapid shield tunneling construction method for sandstone-mudstone interbedded belt cooperation shield tunneling according to claim 1, characterized in that: In step S1, when the sandstone-mudstone interbed shows any of the following characteristics, it is considered unsuitable for setting up a working shaft or as a section division point: ① The joints of the rock strata around the tunnel are developed, the crack length is greater than 3 m, and the spacing is 0.2 - 0.4 m; ② The thickness ratio of the sandstone-mudstone layer is less than 2:1, there are interbedded and disordered layers, sandy mudstone intercalated with thin sandstone layers, or the rock strata at the shield face show strong weathering characteristics; ③ There is a complex soft stratum that is difficult to control from the tunnel top to the ground surface, and there is a high water pressure above 0.5 MPa.

4. The rapid shield tunneling construction method for sandstone-mudstone interbedded belt collaborative shield tunneling according to claim 1, characterized in that: In step S2, in the double-mode shield method, the soil residues generated in the earth pressure mode are output to the muck distributor through the screw conveyor. The muck distributor with two-way transmission transports the muck to the muck temporary storage bin and the muck reprocessing bin. Drainage devices are respectively set in the two bins to separate the excess water of the muck; in the slurry shield stage, the slurry is discharged through the slurry discharge pump. The muck stones, mud materials, and crushed materials are screened and discharged into the muck reprocessing bin. After the muck reprocessing bin drains and crushes the muck inside, the muck is collected in the muck temporary storage bin; when the sensor in the muck temporary storage bin detects that the temporary storage capacity reaches 60% of the total capacity, the temporary storage bin discharges the muck in batches, and the belt unit starts to transport the muck.

5. The rapid shield tunneling construction method of the sandstone-mudstone interlayer belt collaborative shield tunneling according to claim 1, characterized in that: In step S3, the bandwidth of the muck distributor adopts the same operating parameters as the continuous horizontal belt conveyor; at the same time, a hydraulic roller is used to drive the belt to achieve forward and reverse transportation and stepless speed change.

6. The rapid shield tunneling construction method for sandstone-mudstone interbedded belt collaborative shield tunneling according to claim 1, characterized in that: In step S3, image monitoring devices are set at the screw muck outlet and the temporary storage bin muck outlet to collect and screen the muck morphology images. By training and optimizing the convolutional neural network model, BP network model, and Monte Carlo mechanical training technology, automatic classification and feature recognition of muck characteristics are realized according to color, texture, shape, and surface smoothness information, forming a muck image recognition technology.

7. The belt-coordinated shield rapid shield construction method for sandstone-mudstone interbeds according to claim 1, characterized in that: The horizontal continuous belt conveyor support in step S3 includes upper and lower idler groups, retaining edge roller supports, cross beams, and tunnel support components; the upper and lower idler groups and the cross beams are fixed by bolts. The cross beam is an extendable structure, with a group of 50 - 60 m, fixed on the tunnel segment through a lifting link rod, and a small-angle rotation within the range of 0 - 2° of the cross beam is realized through a lifting rod to achieve the change of the dynamic inclination angle; when the belt conveyor passes through the horizontal straight section, the spacing of the upper idler group is 1.2 - 1.6 m, the spacing of the lower idler group is 2.4 - 3.2 m, and a set of retaining edge rollers with discs at the top is arranged every 16 - 20 m. The cross beam is made of I-beam or channel steel, with a length of 2.6 - 3.0 m; when the belt conveyor passes through the horizontal turning section, the spacing of the upper idler group is 0.8 - 1 m, the spacing of the lower idler group is 1.2 - 1.6 m, and a set of retaining edge rollers with discs at the top is arranged every 4 - 5 m.

8. The rapid shield tunneling construction method of the sandstone-mudstone interbedded belt collaborative shield tunneling according to claim 1, characterized in that: In step S6, the maximum transmission capacity Q of the belt conveyor unit, mm 3 / s is: ； In the formula, the shield speed V, in mm / s, the excavation diameter D, in mm, and the density of muck ρ, in g / mm 3 , the stacking coefficient K of the sandstone-mudstone interbedded formation takes values from 1.3 to 1.8 from large to small according to the joint development state of the sandstone and mudstone, and the complex transmission surplus coefficient T takes values of ρ + 0.1 to ρ + 0.25, in g / mm 3 .

9. The rapid shield tunneling construction method for the interbedded sandstone and mudstone belt in cooperation with a shield as claimed in claim 1, wherein: In step S7, multiple sets of deviation-proof rollers and pull cord switches are set along the body of the conveyor system. A blockage monitoring device is set at the muck transfer and unloading places. A backstop is configured for the transmission mechanism, and speed, over-temperature, power-off, and leakage protectors and multi-type protection measures such as sound and light alarms are set for the drive control system to realize dynamic monitoring of the conveyor system, record the operation data throughout the process, automatically stop and alarm in case of abnormal conditions, and fully ensure the safety of personnel and equipment.

Images