Shaft construction method

Abstract

The application discloses a shaft construction method and belongs to the technical field of building construction. The method mainly solves the problems of water gushing and collapse and low process connection efficiency caused by long exposure time of shaft wall rock in traditional process. The method comprises the following steps: excavating an initial shaft section at a designed position of a shaft and installing a prefabricated concrete shaft wall arc plate, embedding a grouting pipe outside the arc plate and welding a ring-shaped water stop steel plate; injecting a cement-water glass double-liquid slurry into a ring-shaped gap to form a closed layer; punching a directional grouting flower pipe along a bottom contour and injecting a rapid-setting double-liquid slurry to form a ring-shaped grouting reinforced body; after installing a telescopic baffle system, excavating in sections, synchronously contracting the baffle system to support the shaft wall rock; after laying a cushion, installing a next shaft wall arc plate and connecting the ring-shaped water stop steel plate through a flange, and repeatedly grouting and excavating until the designed depth. The method is suitable for safe and efficient construction of shafts in water-rich sand layers and fissured strata.

Description

Technical Field

[0001] This invention relates to the field of building construction technology, specifically to a method for constructing vertical shafts. Background Technology

[0002] Shaft engineering has significant applications in mining, transportation, and water conservancy. Traditional construction methods typically employ a top-down, layered excavation combined with cast-in-place concrete support. This method presents several technical challenges, particularly in conditions with abundant groundwater or loose strata.

[0003] Cast-in-place concrete support requires on-site formwork erection and waiting for the concrete to cure, with each curing cycle typically being quite long. During this period, the surrounding rock of the newly excavated well section is exposed without support. When the strata are rich in unconfined or confined water, the water pressure can easily cause the surrounding rock layer to erode, leading to localized spalling or even collapse of the well wall. Some projects have attempted to mitigate this problem by shortening the excavation advance, but frequent support changes have actually prolonged the overall construction period.

[0004] Grouting reinforcement is widely used as an auxiliary method. Conventional segmented grouting is usually implemented after excavation, with a time lag between the grouting and excavation sections. During this period, groundwater continuously seeps into the work face, not only diluting the grout and affecting the consolidation effect, but also potentially causing sand inrush accidents. Engineering practice shows that when the permeability coefficient is greater than 10... -4 In sand layers with a flow rate of cm / s, the success rate of water plugging by delayed grouting is less than 60%.

[0005] To address the issue of temporary support for wellbore surrounding rock, the industry has previously promoted a process combining steel arch frames with shotcrete. However, the installation of the arch frames requires manual positioning and adjustment, which is significantly time-consuming in deep well operations; the shotcrete cannot effectively prevent water seepage before its initial setting, and there are challenges in treating the interface between it and the subsequent permanent well wall. Some projects have attempted to install baffles at the excavation face, but rigid baffles are difficult to adapt to the convergence deformation of the wellbore, and excessive contact pressure may cause the baffles to buckle and fail. Furthermore, if the bottom of the baffle is not anchored, there is a high risk of quicksand flowing into the wellbore.

[0006] Pre-reinforcement techniques for the formation, such as advanced small-diameter grouting, face difficulties in implementation during shaft construction. Drilling equipment operates within limited space in the confined shaft, resulting in insufficient precision in controlling the insertion angle. If the grouting area does not closely adhere to the excavation contour, seepage channels can easily form at the interface. Furthermore, conventional cement grout has a long setting time and is easily washed away under flowing water conditions.

[0007] The contradictions in the coordination of work processes are particularly prominent. To reduce the exposure time of the surrounding rock in the shaft, it is often necessary to shorten the interval between excavation and support, but concrete pouring, grouting, and other operations require strict time windows. When multiple trades are working simultaneously, they are prone to interference. For example, grouting operations may affect the accuracy of formwork installation, while support operations may hinder the removal of excavated material. This contradiction becomes more pronounced when the shaft depth exceeds 20 meters.

[0008] The aforementioned problems stem from the unique three-dimensional confined space conditions inherent in shaft construction: vertical operations are highly concentrated, with limited room for horizontal adjustments; hydrogeological conditions vary with depth; and various processes are interconnected, forming a rigid chain. These characteristics make shaft construction one of the most risky and challenging aspects of underground engineering in terms of both safety and quality control. Summary of the Invention

[0009] This invention provides a method for constructing vertical shafts, aiming to systematically solve several technical problems existing in traditional vertical shaft construction. These mainly include: low efficiency caused by the need to interrupt operations for curing due to integral cast-in-place support; the risk of water inrush and collapse caused by the long exposure time of the surrounding rock during segmented excavation; and the problem of increased ground disturbance caused by the separation of grouting and support processes.

[0010] Meanwhile, this invention also aims to overcome the problems of low efficiency and poor synchronization of manual adjustment of temporary baffle systems, as well as the easy occurrence of quicksand inflow and over-excavation of the excavation profile due to misalignment of the arc-shaped steel plates when the bottom of the baffle system is not anchored.

[0011] At the system control level, this invention further solves the problems of baffle system distortion and deformation caused by pressure imbalance in multi-cylinder hydraulic systems, seal failure caused by asynchronous displacement, and difficulty in real-time response to formation changes by manual monitoring.

[0012] To address the reliability issues of hydraulic systems, this invention also addresses valve assembly jamming caused by hydraulic oil contamination, oil leakage due to high-pressure seal failure, and the disruption to construction continuity caused by filter blockage requiring downtime for replacement.

[0013] In terms of grouting technology, this invention aims to improve the contradictions of insufficient grout diffusion in water-rich strata under fixed grouting pressure, ineffective sealing of large cracks by low-pressure grouting, and easy fracturing of weak strata by high-pressure grouting; at the same time, it solves the problems of grout waste caused by excessively low viscosity due to mismatch between grout rheology and stratum permeability characteristics, pipe blockage caused by excessively high viscosity, and the impact of delayed manual adjustment on grouting quality.

[0014] Furthermore, this invention also proposes improvements to address the problems of uneven additive mixing leading to clumping and affecting slurry homogeneity during slurry preparation, unfiltered impurities accelerating grouting pump wear, and low-speed stirring exacerbating slurry segregation and stratification. It also solves the problems of high-viscosity slurry clogging the flow channel and low-viscosity slurry insufficient shear force due to the inability of the fixed gap design to adapt to viscosity changes. At the same time, it solves the problems of slurry resistance fluctuation affecting control accuracy, spring fatigue reducing pre-pressure control accuracy, and hydraulic impact damaging the displacement adjustment mechanism.

[0015] To achieve these and other advantages according to the present invention, a method for constructing a vertical shaft is provided, comprising the following steps:

[0016] Step 1: Excavate an initial shaft section with a depth of 8 to 12 meters at the designed location of the vertical shaft;

[0017] Step 2: Install the first section of the well wall arc plate circumferentially on the inner wall of the initial well section. Embed a longitudinal grouting pipe on the outer side of the first section of the well wall arc plate. The grout outlet of the grouting pipe extends to the outer surface of the first section of the well wall arc plate, and the grout inlet of the grouting pipe is located on the inner surface.

[0018] Step 3: Weld the first annular water-stop steel plate circumferentially to the inner side of the bottom end of the first section of the well wall arc plate. The inner diameter of the first annular water-stop steel plate is the same as the inner diameter of the first section of the well wall arc plate, with a ring width of 300 mm to 500 mm and a thickness of 20 mm to 30 mm.

[0019] Step 4: Inject cement-water glass dual-liquid grout into the annular gap outside the first section of the well wall arc plate through the grout inlet of the grouting pipe. The grouting pressure is 1.5 MPa to 2.5 MPa. Continue grouting until the grout returns from the adjacent grouting pipe.

[0020] Step 5: After the grouting body reaches a strength of 2 MPa to 3 MPa, drive a directional grouting pipe circumferentially 30 to 50 centimeters outside the current wellbore bottom outline. The length of the pipe is equal to the next excavation depth plus 1 meter, and the inclination angle is 10 to 15 degrees.

[0021] Step 6: Inject a quick-setting dual grout of ultrafine cement slurry and water glass in a volume ratio of 1:0.3 to 1:0.5 into the formation through a directional grouting pipe. The gelation time is 3 to 8 seconds, forming a ring-shaped grouting solid with a thickness of 200 mm to 400 mm.

[0022] Step 7: Remove the directional grouting pipe and install a telescopic steel baffle system at the bottom of the current wellbore. The baffle system consists of multiple curved steel plates with a height of 500 mm to 800 mm that are hinged together.

[0023] Step 8: Under the support of the baffle system, excavate the next section of the shaft to a depth of 4 to 6 meters. After each 1-meter excavation, the baffle system is simultaneously contracted to make the inner wall of the arc-shaped steel plate fit the surrounding rock of the newly excavated shaft.

[0024] Step nine: Remove the baffle system and lay a 200-300 mm thick concrete cushion layer at the bottom of the excavated shaft;

[0025] Step 10: Install the second section of the well wall arc plate. Weld the second annular water-stop steel plate to the inner side of its top. The top of the second section of the well wall arc plate is connected to the bottom of the first section of the well wall arc plate by flange bolts, so that the two annular water-stop steel plates fit tightly together.

[0026] Step 11: Pressure grouting is performed through the second section of the well wall arc plate grouting pipe;

[0027] Step 12: Repeat steps 5 through 11 until the designed well depth is reached.

[0028] In this technical solution, each section of the well wall arc plate is made of precast concrete.

[0029] Preferably, in the vertical shaft construction method of the present invention, the retractable steel baffle system in step seven has a hydraulic jacking device provided on the inner side of the arc-shaped steel plate.

[0030] The operation of the synchronous shrinkage baffle system in step eight is as follows: for every 1 meter of downward excavation, the hydraulic jacking device is activated to cause the arc-shaped steel plate to shrink radially by 50 mm to 80 mm; rubber sealing strips are installed at the joints of adjacent arc-shaped steel plates; detachable anchor bolts are installed at the bottom of the baffle system, and the anchor bolts are inserted into the pre-drilled holes in the formation at the bottom of the well to fix the position of the baffle system.

[0031] Preferably, in the vertical shaft construction method of the present invention, pressure sensors and flow control valves are installed on the oil circuit of the hydraulic jacking device; all pressure sensors are connected to an interlock controller, and the interlock controller sets the working pressure difference threshold between adjacent arc-shaped steel plate cylinders to 1.0 MPa to 1.5 MPa;

[0032] When the real-time pressure difference between the cylinders of two adjacent arc-shaped steel plates exceeds the threshold, the interlock controller performs the following operations: reduces the oil inlet flow of the high-pressure side cylinder to 60% to 80% of the rated flow, while increasing the oil inlet flow of the low-pressure side cylinder to 100% to 110% of the rated flow.

[0033] When the displacement difference between adjacent curved steel plates exceeds 5 mm, pressurized oil is injected into the lag cylinder to increase the pressure to 1.8 MPa to 2.2 MPa, triggering an audible and visual alarm.

[0034] Preferably, in the vertical shaft construction method of the present invention, a high-pressure filter is connected in parallel on the main hydraulic oil line, the oil inlet of the high-pressure filter is connected to the rodless chamber of the oil cylinder, and the oil outlet is connected to the oil tank.

[0035] Differential pressure sensors are installed at the inlet and outlet of the high-pressure filter. When the inlet and outlet pressure difference is greater than 0.4 MPa to 0.6 MPa, the bypass valve is opened to allow the oil to flow through the standby filter.

[0036] The hydraulic cylinder piston rod is sealed with a combination of fluororubber O-rings and polyurethane seals.

[0037] Preferably, in the vertical shaft construction method of the present invention, during the pressure grouting process in steps four and eleven, the following operations are performed:

[0038] The water pressure outside the grouting section is monitored in real time by a water pressure sensor installed inside the well.

[0039] The initial grouting pressure is set to 1.1 to 1.3 times the real-time water pressure.

[0040] When the volume of grout injected reaches 0.5 to 0.8 cubic meters, the grouting pressure is increased to 0.1 to 0.2 times the real-time water pressure; grouting is stopped when the grouting pressure reaches 3.0 to 4.0 MPa or the grouting volume reaches the design value.

[0041] The grouting material is a composite grout composed of ultrafine cement and silica fume in a mass ratio of 9:1 to 8:2, with a water-cement ratio of 0.6 to 0.8.

[0042] Preferably, in the vertical shaft construction method of the present invention, an online rheometer is installed at the outlet of the grouting pump to monitor the grout viscosity η and shear stress τ in real time.

[0043] The target rheological parameters of the grout are set as follows: viscosity η0 = 0.02 × K + 30 (unit: cP), shear stress τ0 = 0.15 × K + 120 (unit: Pa), where K is the formation permeability coefficient (unit: mD), and the value of K ranges from 10 mD to 150 mD; when K < 10 mD, it is calculated as K = 10 mD, and when K > 150 mD, it is calculated as K = 150 mD. The parameters are obtained by performing a three-stage pressure test in accordance with the "Technical Specification for Grouting of Water Conservancy and Hydropower Engineering" (DL / T 5148-2021).

[0044] When the real-time monitoring value η deviates from η0 by more than ±15% or τ deviates from τ0 by more than ±20%, perform the following operations:

[0045] If η > 1.15η0, add water-reducing agent to the slurry to increase the water-cement ratio by 0.05 to 0.1;

[0046] If η < 0.85η0, add bentonite to the slurry to increase the solid content by 3% to 5%;

[0047] After adjustment, let stand and stir for 3 to 5 minutes, then monitor again until the rheological parameters meet the standards.

[0048] Preferably, in the vertical shaft construction method of the present invention, a slurry pretreatment unit is installed before the grouting pump inlet. The unit includes a high-speed mixing tank with a mixing speed of 800 rpm to 1200 rpm.

[0049] After adding bentonite or water-reducing agent to the slurry, the slurry is processed in a high-speed mixing tank for 90 to 120 seconds.

[0050] The pretreated slurry is filtered through an 80-100 mesh filter before entering the grouting pump.

[0051] Preferably, in the vertical shaft construction method of the present invention, a two-stage slurry mixer is installed inside the high-speed mixing tank; the two-stage slurry mixer includes:

[0052] The first-stage spiral premixing unit consists of 6 to 8 fixed spiral blades evenly distributed around the circumference, with a blade inclination angle of 45 to 60 degrees, and is installed below the feed inlet of the mixing tank.

[0053] The second-stage shear control unit includes a rotor coaxially mounted at the end of the stirring shaft and a stator fixed to the inner wall of the tank. The rotor has a trapezoidal groove with a depth of 3 mm to 5 mm on its surface, and the inner wall of the stator is provided with axial ribs.

[0054] Gap adjustment mechanism: The rotor is connected to the stirring shaft via a hydraulic cylinder. The hydraulic cylinder pressure P and the real-time viscosity η of the slurry satisfy the following relationship: P = 0.5 × η + 10 (unit: MPa, η unit: cP); where η is calibrated in real time by an online viscosity sensor; when the calculated value of P exceeds 100 MPa, the pressure is limited to 100 MPa; the rotor is driven to move axially, so that the gap between the rotor and the stator is maintained within the range of 0.5 mm to 3.0 mm.

[0055] Preferably, in the shaft construction method of the present invention, the gap adjustment mechanism includes:

[0056] A preloaded disc spring assembly is coaxially connected to the back of the rotor. The spring assembly stiffness coefficient is 50 N / mm to 80 N / mm, and the pre-compression is 30% to 40% of the total stroke.

[0057] A double-acting compensation chamber is formed between the rotor and the piston rod of the hydraulic cylinder. The upper chamber of this compensation chamber is connected to the hydraulic system and maintains a constant pressure. P base =10±0.5MPa, the lower cavity is filled with a carboxymethyl cellulose aqueous solution with a mass fraction of 8% to 12%;

[0058] The maximum axial displacement Δ of the rotor L Satisfy: Δ L =( F 浆 - F 预 ) / C， in F 浆 F represents the resistance of the slurry acting on the rotor (unit: Newtons). 浆 =ΔP×A, where ΔP is the pressure difference across the rotor, collected in real time by a pressure sensor (unit: Pa), ΔP≤0.5 MPa, and A is the effective pressure-bearing area of ​​the rotor, the effective projected area of ​​the rotor subjected to slurry pressure (unit: m²). 2 ), 0.005 m 2 ≤A≤0.01 m 2 Fpre is the spring preload (unit: Newtons). 预 =C×δ, where δ is the pre-compression amount, the initial compression deformation of the spring (unit: mm). C The spring stiffness coefficient (unit: N / mm);

[0059] The rotor is equipped with an axial displacement sensor to monitor Δ in real time. L Actual value; when Δ L When the deviation between the actual value and the calculated value exceeds ±0.5mm, the hydraulic cylinder automatically compensates for the pressure Δ. L The range of regression theoretical values.

[0060] The present invention has at least the following beneficial effects:

[0061] 1. Precast arc plates and rapid-setting grouting work together to shorten the single-cycle operation period and significantly reduce the exposure time of the surrounding rock in the wellbore. Dual-liquid grouting quickly seals the aquifer, and the annular grouting reinforcement provides effective pre-support, suppressing the risk of sand inrush and collapse. Segmented flange connections ensure wellbore continuity, and double-ring water-stop steel plates block leakage paths. Dynamic process connections adapt to complex geology and improve the structural integrity of the shaft.

[0062] 2. Hydraulic synchronous drive enables precise contraction of the baffle system, improving adjustment efficiency and synchronization. Contraction is coordinated with soil deformation to maintain the stability of the surrounding rock in the wellbore. Bottom anchoring blocks the inflow of quicksand. Elastic sealing strips compensate for joint deformation to prevent debris from falling. Modular design enhances construction safety.

[0063] 3. Pressure-flow interlock control maintains balanced cylinder pressure, preventing baffle system distortion. Automatic displacement compensation eliminates the risk of seal failure. Audible and visual alarms provide real-time alerts for abnormalities, shortening response time. Closed-loop control ensures the accuracy of the baffle system's movement trajectory, reducing over-excavation.

[0064] 4. Dual filters in parallel enable continuous operation, avoiding downtime losses. Precise differential pressure control ensures unobstructed oil flow. The composite sealing structure withstands high-pressure environments, significantly reducing the risk of leakage. Oil cleaning monitoring extends system lifespan.

[0065] 5. A dynamic pressure regulation mechanism optimizes the grout diffusion range and improves crack filling effect. A gradient pressure increase strategy balances the risks of seepage and fracturing. Composite grout reduces water seepage rate and maintains unobstructed pipelines. Optimized water-cement ratio enhances the density and waterproofing performance of the consolidated body.

[0066] 6. Rheological parameters related to formation permeability are set to ensure the slurry matches geological conditions. Real-time monitoring and adjustment prevent slurry leakage and pipe blockage. A quantitative addition mechanism improves the accuracy of the proportions. Static stirring enhances the uniformity of additive dispersion.

[0067] 7. High-speed shearing ensures thorough dispersion of additives and eliminates unhydrated particles. A filter screen intercepts impurities, protecting the grouting equipment. Optimized flow channel design reduces slurry segregation. Variable frequency speed control adapts to different operating conditions.

[0068] 8. The premixing unit improves slurry uniformity, and the shear groove enhances dispersion. Viscosity-adaptive gap adjustment prevents channel blockage and failure. The ribbed structure enhances radial shear force. A fault protection mechanism ensures system reliability.

[0069] 9. Elastic preload and differential pressure feedback work together to control displacement accuracy. Closed-loop displacement control improves adjustment accuracy. Dedicated lubricating medium reduces seal wear. Regular inspection mechanism ensures long-term stability. Overload protection device maintains system safety.

[0070] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Detailed Implementation

[0071] The present invention will now be described in further detail so that those skilled in the art can implement it based on the description.

[0072] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0073] According to one embodiment of the present invention, a method for constructing a vertical shaft is provided. An initial shaft section with a depth of 10 meters and a diameter of 5 meters is excavated at the designed location of the shaft. A standard backhoe excavator can be used for earthmoving operations. During excavation, the verticality deviation of the surrounding rock is controlled within ±30 mm. A first section of the shaft wall arc plate is installed on the inner wall of the initial shaft section. This first section of the shaft wall arc plate is prefabricated using C40 concrete, with each arc plate being 1.2 meters wide and 1.5 meters high. A 25 mm diameter seamless steel pipe is pre-embedded on the outer side of the first section of the shaft wall arc plate as a grouting pipe. The grout outlet of the grouting pipe protrudes 10 mm from the outer surface of the first section of the shaft wall arc plate, and the grout inlet of the grouting pipe is flush with the inner surface of the first section of the shaft wall arc plate.

[0074] The first annular water-stop steel plate was welded circumferentially to the inner side of the bottom end of the first section of the well wall arc plate. The annular water-stop steel plate was made of Q235B steel plate, with an inner diameter of 5 meters, a ring width of 400 mm, and a thickness of 25 mm, and was fixed by continuous full welding. Cement-water glass dual-liquid grout was injected through the grouting pipe inlet. The cement used was PO 42.5 grade ordinary Portland cement, and the water glass modulus was 2.8 with a concentration of 35 Baume. The initial grouting pressure was set at 2.0 MPa, and grouting was stopped when grout returned to the adjacent grouting pipe. The strength of the grout was tested by core samples drilled on site and loaded using a pressure testing machine. Subsequent operations were carried out after the strength reached 2.5 MPa.

[0075] After the grout reaches the required strength, a directional grouting pipe is driven circumferentially 40 cm outside the bottom outline of the wellbore. The pipe is a 6-meter-long, 42 mm diameter geological steel pipe with a 12-degree inclination. A quick-setting dual-slurry mixture of ultrafine cement slurry and water glass (volume ratio 1:0.4) is injected through the pipe, with a gel time of 5 seconds, forming a 300 mm thick annular grouting layer. Water glass can be replaced with an acrylate quick-setting agent, with the gel time adjusted from 3 to 10 seconds.

[0076] After removing the perforated pipe, a retractable steel baffle system is installed. The baffle system consists of eight 600mm high, 12mm thick Q345B curved steel plates hinged together. With the baffle system in place, a 5-meter deep shaft section is excavated. After each meter of excavation, the baffle system is manually retracted, moving the curved steel plates radially inward by 60mm. A 1.2-meter long, 22mm diameter threaded steel anchor bolt is installed at the bottom of the baffle system and inserted into a pre-drilled hole at the bottom of the shaft for fixation.

[0077] After removing the baffle system, a 250 mm thick C20 concrete pad is laid at the bottom of the well. The second section of the well wall arc plate is installed, with a second annular water-stop steel plate of the same specification welded to its inner top. The two sections of the well wall arc plate are connected by M20 flange bolts with a bolt spacing of 200 mm and a tightening torque of 300 N·m. The flange sealing is verified by a 0.5 MPa water pressure test, with no leakage after 10 minutes of pressure holding. Pressure grouting is then performed through the second grouting pipe, following the same grouting procedure as the first section. The above excavation and support process is repeated until the designed well depth is reached.

[0078] The method of this embodiment controls the deformation of the formation through phased construction: the initial shaft section is 10 meters deep to provide working space; double-liquid grouting forms a closed water-stopping layer; the annular grouting reinforcement body strengthens the formation at a 12-degree inclination angle at the front of the excavation; the shrinkage of the baffle system is 60 mm per meter to match the relaxation rate of the soil layer; and two annular water-stopping steel plate flanges are connected to achieve sealing.

[0079] Compared to the traditional 7-day curing period required for cast-in-place concrete shaft construction, the method described in this implementation shortens the single-cycle operation to 48 hours through precast arc slabs and rapid-setting grouting. The baffle system reduces the exposure time of the surrounding rock in the shaft to 4 hours, effectively controlling the risk of sand inrush during construction in water-rich sand layers.

[0080] According to another embodiment of the present invention, a method for constructing a vertical shaft is provided. When installing a retractable steel baffle system at the bottom of the shaft, the eight arc-shaped steel plates of the baffle system are made of Q345B steel, with each arc-shaped steel plate having a height of 600 mm and a thickness of 12 mm. A hydraulic jacking device is welded and installed on the inner side of the arc-shaped steel plates. This device can be a single-acting hydraulic cylinder with a stroke of 80 mm and a working pressure of 16 MPa. The cylinder base is fixed to the inner reinforcing ribs of the arc-shaped steel plates by bolts, and the piston rod end is connected to a push-pull rod in the direction of the shaft center.

[0081] During the downward excavation of the wellbore, the baffle system is retracted after every 1 meter of excavation. The operator activates the hydraulic station control valve, synchronously supplying oil to the rodless chambers of all cylinders, driving the piston rod to extend 60 mm, causing the curved steel plate to retract radially inward by 60 mm. EPDM rubber sealing strips with a cross-sectional dimension of 10 mm × 8 mm are installed at the joints of adjacent curved steel plates. Removable anchor bolts are installed at the bottom of the baffle system; these can be made of 22 mm diameter HRB400 threaded steel and are 1.2 meters long. A 28 mm diameter hole, 1.0 meter deep, is pre-drilled in the formation at the bottom of the well. After the anchor bolt is inserted, cement-based grout is injected to secure it.

[0082] During the retraction operation of the baffle system, the pressure of each hydraulic cylinder is monitored by the hydraulic pressure gauge, and the pressure difference between adjacent hydraulic cylinders is controlled to not exceed 1.2 MPa. After the anchor bolts are installed, a pull-out test is performed according to the "Standard for Acceptance of Construction Quality of Building Foundation Engineering" GB50202, with a load of 50 kN held for 2 minutes.

[0083] Compared to traditional wooden formwork support, which requires 2 hours of on-site processing and installation, the baffle system in this embodiment completes its shrinkage adjustment within 30 minutes. Hydraulic synchronous drive avoids misalignment of the curved steel plates caused by manual hammering adjustments, and the joint sealing strip effectively prevents gravel from falling. The anchor bolt fixing method solves the problem of sand gushing from the bottom of the baffle system in quicksand strata.

[0084] According to another embodiment of the present invention, a vertical shaft construction method is provided, wherein pressure sensors and flow control valves are installed in the oil circuit of a hydraulic jacking device. The pressure sensors can be piezoresistive type, with a range of 0-25 MPa and an accuracy of ±0.5%FS, and are installed at the tee interface of the inlet and outlet pipelines of each cylinder. The flow control valves are proportional regulating type, with a rated flow rate of 20 liters / minute, and are integrated into the main oil circuit distribution block of the hydraulic station. All pressure sensor signal lines are connected to an interlocking controller, which can be a PLC programmable logic module with a built-in control program setting the threshold for the working pressure difference between adjacent cylinders to 1.2 MPa.

[0085] When the wellbore reaches the gravel and sand strata, the hydraulic cylinder pressure of the two adjacent curved steel plates is monitored in real time. If the pressure of the left hydraulic cylinder is 3.8 MPa and the pressure of the right hydraulic cylinder is 2.3 MPa, and the pressure difference reaches 1.5 MPa, exceeding the threshold, the interlock controller automatically performs regulation: reducing the opening of the proportional valve of the left hydraulic cylinder to 65%, reducing the flow rate to 70% of the rated flow rate; simultaneously increasing the opening of the proportional valve of the right hydraulic cylinder to 105%, increasing the flow rate to 110% of the rated flow rate. The measured regulation response time is within 200 milliseconds.

[0086] During the retraction of the baffle system, the displacement of adjacent curved steel plates is monitored by a rope displacement sensor. A 100mm stroke sensor with a measurement accuracy of ±0.1mm can be selected and installed above the hinge point of adjacent curved steel plates. When the detected displacement of the front curved steel plate reaches 42mm and the rear curved steel plate 30mm, with a displacement difference of 12mm, the interlock controller injects pressurized oil into the lagging cylinder, switching the oil circuit via a solenoid directional valve to raise the pressure of that cylinder to 2.0 MPa. Simultaneously, a buzzer and red warning light are triggered to alert the operator to check for formation anomalies.

[0087] During the hydraulic system commissioning phase, interlocking tests were conducted: A pressure difference of 1.6 MPa was manually set between adjacent cylinders to verify that the controller automatically initiated the flow regulation program within 0.5 seconds; a displacement difference of 15 mm was set to verify that the pressure boosting response and audible / visual alarm functions were normal. The hydraulic oil used for the tests was No. 46 anti-wear hydraulic oil, and the oil temperature was controlled at 40±5 degrees Celsius.

[0088] When the interlocking controller fails, perform the following operations:

[0089] (1) Close the main oil circuit valve of the hydraulic station and lock the position of all oil cylinders;

[0090] (2) Use mechanical jacking devices (such as screw jacks) to maintain the curvature of the baffle system;

[0091] (3) Trigger the audible and visual alarm system, suspend excavation and inspect the hydraulic system.

[0092] Compared to traditional manual hydraulic systems that require more than three manual interventions, this implementation method improves the synchronization accuracy of the baffle system to a displacement difference of ≤5 mm through automatic interlocking control. Real-time pressure regulation prevents cylinder overload damage, and audible and visual alarms promptly alert to the risk of formation heterogeneity.

[0093] According to another embodiment of the present invention, a vertical shaft construction method is provided, wherein a high-pressure filter system is installed in parallel on the main hydraulic oil line. The high-pressure filter can be a model with a filtration accuracy of 10 micrometers and a rated pressure of 40 MPa, connected via a flange interface. The filter inlet is connected to the rodless chamber oil circuit of the cylinder via a tee connector, and the outlet is connected to the oil tank via a return oil pipe. Differential pressure sensors are installed at the filter inlet and outlet ends. These sensors have a range of 0-1.0 MPa and an accuracy of ±1%FS, and their threaded interfaces are directly assembled to the pressure measurement points in the oil line.

[0094] The differential pressure of the filters is monitored in real time during hydraulic system operation. When the oil temperature is 50 degrees Celsius, the differential pressure between the inlet and outlet of the newly installed filter is 0.15 MPa. After 120 hours of continuous operation, the differential pressure rises to 0.52 MPa, exceeding the 0.5 MPa threshold. The differential pressure sensor outputs a signal to the control box, and the solenoid valve drives the bypass valve to open. At this time, the oil is diverted to the standby filter, which has the same model and specifications as the main filter. During the switching process, the system pressure fluctuation is controlled within ±0.8 MPa. When both filters are clogged, the standby oil circuit is activated to directly supply oil, triggering the load reduction mode (pressure limit 10 MPa).

[0095] The hydraulic cylinder piston rod seal adopts a combined structure. A fluororubber O-ring and a polyurethane step seal are sequentially installed in the piston rod sealing groove. The O-ring has a cross-sectional diameter of 3.5 mm, and the step seal lip thickness is 2 mm. Before installation, the seals are soaked in hydraulic oil for 24 hours, with the lip facing the pressure side during installation. After cylinder assembly, a pressure test is performed: the piston rod reciprocates 50 times, and a working pressure of 16 MPa is maintained for 30 minutes; no oil film seeps out from the piston rod surface.

[0096] The hydraulic oil used is No. 46 anti-wear hydraulic oil, which is filtered through a 100-mesh filter before operation. During system operation, the oil cleanliness is checked every 48 hours, and the contamination level is controlled to not exceed ISO 18 / 15 according to the standard GB / T 14039 "Hydraulic Transmission Oil Solid Particle Contamination Level Code". The oil is replaced when the water content exceeds 0.05%.

[0097] Compared to single-filter systems that require shutdown for filter replacement, this implementation achieves continuous operation through parallel operation of dual filters. The combined sealing structure showed no leakage after a 200-hour durability test at 16 MPa pressure, meeting the requirements of high-dust environments during shaft construction.

[0098] According to another embodiment of the present invention, a method for constructing a vertical shaft is provided. During the grouting process of the first section of the shaft wall arc plate, the water pressure outside the shaft is monitored in real time by a pre-embedded water pressure sensor. The water pressure sensor can be a diffused silicon piezoresistive type with a range of 0-5 MPa, installed at the arc plate joint in the middle of the grouting section. The measured current sand layer water pressure is 1.8 MPa, and the initial grouting pressure is set to 1.2 times 1.8 MPa, i.e., 2.16 MPa. The grouting pump can be a three-cylinder plunger type with a rated pressure of 6 MPa.

[0099] After grouting begins, the grouting pressure is increased by 0.2 times the real-time water pressure (0.36 MPa) for every 0.6 cubic meters of grout injected. When a total of 3.2 cubic meters of grout has been injected, the grouting pressure rises to 3.1 MPa, and grouting is stopped after reaching the designed grouting volume of 3.5 cubic meters. The grouting material is prepared by mixing ultrafine cement and silica fume at a mass ratio of 85:15. The ultrafine cement particle size D50 is ≤8 micrometers, and the silica fume specific surface area is ≥15000 square meters / kg. The water-cement ratio of the grout is controlled at 0.7, and the mixing time is no less than 5 minutes.

[0100] During the grouting of the second section of the wellbore's arc plate, the measured formation water pressure was 2.3 MPa. The initial grouting pressure was set to 1.15 times 2.3 MPa, i.e., 2.65 MPa. The pressure was increased by 0.25 MPa for every 0.7 cubic meters of grout injected, and the pump automatically stopped when the pressure reached 3.8 MPa. The grout mix ratio was adjusted to ultrafine cement: silica fume = 82:18 (by mass), with a water-cement ratio of 0.65.

[0101] The grout was prepared using a forced mixer. The feeding sequence was as follows: (1) 70% of the total water was added first; (2) the mixed dry materials were added slowly and stirred for 3 minutes; (3) the remaining water was added and stirred for 2 minutes. The pressure-flow curve was recorded during the grouting process. If the pressure change exceeded 0.5 MPa, the grouting was stopped and the pipeline blockage was checked.

[0102] Compared to fixed-pressure grouting, this implementation method uses dynamic pressure adjustment linked to water pressure, increasing the grout diffusion radius to 1.8 meters in sand grouting and achieving a formation fracture filling rate of over 95%. The composite grout reduces the water separation rate to below 5%, avoiding pipe blockage accidents.

[0103] According to another embodiment of the present invention, a method for constructing a vertical shaft is provided. An online rheometer is installed on the outlet pipeline of the grouting pump. This rheometer can be a rotational viscometer with a measurement range of 1-1000 cP, and is integrated between the pump outlet three-way valve and the grouting pipe. The rheometer outputs real-time data on the grout viscosity η and shear stress τ to the control console display screen. Before grouting, three test holes are drilled around the vertical shaft, and a water pressure test is performed according to the "Technical Specification for Grouting of Water Conservancy and Hydropower Engineering" DL / T 5148, and the permeability coefficient of the sandy stratum is measured to be K=45mD.

[0104] The target rheological parameters were set as follows: viscosity η0 = 0.02 × 45 + 30 = 30.9 cP, shear stress τ0 = 0.15 × 45 + 120 = 126.75 Pa. The grouting pump was started to inject a composite grout with a water-cement ratio of 0.7. The initial real-time monitoring values ​​were η = 35.2 cP (exceeding 1.15η0 = 35.535 cP) and τ = 131 Pa (within τ0 ± 20%). At this point, polycarboxylate superplasticizer was added to the grout storage tank at a rate of 0.8% of the cementitious material mass, while simultaneously increasing the water volume to raise the water-cement ratio to 0.76. After addition, the mixture was allowed to stand and stir for 4 minutes, and the η value was retested at 31.5 cP, reaching the target range.

[0105] During grouting in the fractured formation, K=12 mD was measured, with target values ​​η0=0.02×12+30=30.24 cP and τ0=0.15×12+120=121.8 Pa. In actual grouting, η=26.1 cP was monitored (lower than 0.85η0=25.7 cP). Sodium-based bentonite was added to the mixing tank at a rate of 3.5% of the grout volume. After continuous mixing for 5 minutes, η=29.8 cP and τ=119 Pa were measured again, meeting the requirements.

[0106] Grout adjustment is performed at a dedicated grout mixing station. The grouting pump is paused when adding water-reducing agent or bentonite. The rheometer collects data every 10 seconds, and the control panel automatically alarms if the data deviates from the set threshold. Bentonite is sieved through a 100-mesh screen before addition, and the water-reducing agent is diluted 10 times with water before injection.

[0107] Compared to fixed-ratio grouting methods, this implementation method reduces grout loss by approximately 30% in sand grouting and increases the effective grout diffusion distance in formation fractures to 1.3 times the design value. Real-time rheological control avoids abnormal fluctuations in grouting pressure.

[0108] According to another embodiment of the present invention, a vertical shaft construction method is provided, wherein a grout pretreatment unit is installed at the inlet of the grouting pump. This unit includes a high-speed mixing tank with a volume of 1.5 cubic meters and a mixing shaft power of 22 kW. The mixing tank can be a double-layer propeller structure, with the upper blade diameter being 600 mm and the lower blade diameter being 500 mm. The drive motor is controlled by a frequency converter to rotate at 1000 rpm, corresponding to a linear velocity of 8.3 m / s.

[0109] After adding bentonite, the slurry is pumped into a high-speed mixing tank. The processing time is controlled at 100 seconds, during which the slurry temperature rises from 25 degrees Celsius to 32 degrees Celsius. After mixing is complete, the discharge valve at the bottom of the tank is opened, and the slurry flows through a 90-mesh stainless steel filter screen into the grouting pump suction pipe. The filter screen can be made of 304 stainless steel, with an effective filtration area of ​​0.6 square meters, and is installed within a frame inclined at 45 degrees.

[0110] When adding water-reducing agent, first premix the agent with 10 times its weight of water in the auxiliary mixing tank for 3 minutes, then inject it into the high-speed mixing tank. Taking a slurry with a water-cement ratio of 0.76 as an example, after adding the water-reducing agent, treat for 95 seconds, and then filter the slurry through an 85-mesh filter. After processing every 20 cubic meters of slurry, remove the filter and clean it by backwashing with a 0.5 MPa water gun.

[0111] The pretreatment unit is no more than 5 meters away from the grouting pump, and the connecting pipeline uses DN80 seamless steel pipe. Baffles, 150 mm high, are installed on the inner wall of the mixing tank, with 6 baffles evenly distributed around the circumference. Operational tests show that after 100 seconds of treatment, the slurry segregation rate drops to 0.8%, and the maximum unfiltered particle size is ≤0.2 mm.

[0112] Compared to directly pumping the adjusted grout, the pretreatment unit in this embodiment increases the bentonite dispersion to over 95%, and the average particle size of the crust impurities intercepted by the filter screen is 0.5 mm. High-speed shearing treatment eliminates the local enrichment of water-reducing agent, and the volumetric efficiency of the grouting pump is maintained above 92%.

[0113] According to another embodiment of the present invention, a method for constructing a vertical shaft is provided, comprising installing a two-stage slurry mixer inside a high-speed mixing tank. The first-stage spiral premixing unit is located 300 mm below the feed inlet and consists of six circumferentially distributed fixed spiral blades made of 304 stainless steel, with a single blade having a projected area of ​​0.05 square meters and an installation angle of 50 degrees. The second-stage shear control unit is located at the bottom of the tank, with the rotor connected to the end of the mixing shaft via a flat key. The rotor diameter is 100 mm, and the effective pressure-bearing area A is calculated based on the rotor's projected area: A = π × (rotor radius). 2 =3.14×(0.05) 2 =0.00785 m 2 The surface has a trapezoidal groove 4 mm deep and 3 mm wide at the bottom. The stator is fixed to the inner wall of the tank, which has 8 axial ribs with a height of 6 mm. The material of the ribs is wear-resistant tungsten carbide.

[0114] When the slurry viscosity η = 35 centipoise, the hydraulic system adjusts the pressure according to the formula P = 0.5 × 35 + 10 = 27.5 MPa. η is calibrated in real time by an online viscosity sensor at the mixing tank outlet. When the calculated value of P > 100 MPa, the pressure is automatically limited to 100 MPa. In case of viscosity sensor failure, the rotor automatically returns to a safe position, widening the gap to 3.0 mm. A double-acting servo cylinder with an 80 mm diameter can be used to drive the rotor axially. At this time, the gap between the rotor and stator is adjusted to 1.8 mm, falling within the range of 0.5 to 3.0 mm. The gap value is monitored in real time by an inductive displacement sensor mounted on the back of the rotor, with a range of 0-5 mm and an accuracy of ±0.02 mm.

[0115] After assembly, the mixer underwent a no-load test: using clean water as the medium, it ran at 1000 rpm for 30 minutes, with the rotor axial movement ≤0.1 mm. The load test used cement slurry with a water-cement ratio of 0.75. At a viscosity η=40 centipoise, the hydraulic pressure automatically increased to 30 MPa, and the gap was adjusted to 1.2 mm. The test results showed that after two-stage treatment, the proportion of particles larger than 0.1 mm in diameter decreased to below 3%.

[0116] The hydraulic system oil temperature is controlled at 45±3 degrees Celsius. When the viscosity sensor malfunctions, the rotor automatically returns to a safe position, widening the gap to 3.0 mm. The trapezoidal grooves have an inclination angle of 60 degrees and a groove spacing of 15 mm, generating a vortex shear flow as the slurry passes through the grooves.

[0117] Compared to a single-stage mixing structure, the mixer in this embodiment reduces the bentonite dispersion time by 60% and the slurry segregation rate to 0.5% per hour. Dynamic gap adjustment prevents high-viscosity slurry from clogging the stator-rotor gap, and the rib structure enhances the radial turbulence effect.

[0118] According to another embodiment of the present invention, a vertical shaft construction method is provided, wherein a preloaded disc spring assembly is coaxially mounted on the back of the rotor in the gap adjustment mechanism of a two-stage slurry mixer. The spring assembly consists of eight 60Si2MnA disc springs connected in series, each with a thickness of 4 mm and an outer diameter of 85 mm. The spring assembly has a stiffness coefficient of 65 N / mm, and the initial pre-compression is 35% of the maximum stroke of 10 mm, i.e., 3.5 mm. The spring seat is fixed to the rotor back plate by a locating pin, and the preload F 预 =65 N / mm × 3.5 mm = 227.5 N. The pressure difference ΔP across the rotor is acquired in real time by a pressure sensor installed on the rotor end face (range 0-0.5 MPa, accuracy ±0.1%).

[0119] A double-acting compensation chamber is formed between the rotor and the piston rod of the hydraulic cylinder. The upper chamber is connected to the hydraulic station pipeline to maintain a constant base pressure P. base =10.2 MPa, fluctuation range ±0.3 MPa. The lower cavity is filled with a 10% (w / w) aqueous solution of carboxymethyl cellulose, with a solution viscosity of 120 centipoise. The compensation cavity is sealed with a double-layer fluororubber seal, and the sealing surface roughness Ra ≤ 0.4 micrometers.

[0120] When the slurry acts on the axial resistance F of the rotor 浆 =ΔP×A=0.08×10 6 Pa × 0.00785 m 2 =628 N; (A=0.00785 m) 2When the measured pressure is ΔP = 0.08 MPa and C = 65 N / mm, the maximum axial displacement of the rotor is ΔL = (628 - 227.5) / 65 ≈ 6.16 mm (within a 10 mm stroke). The displacement sensor monitors the actual displacement value in real time as 6.20 mm, which deviates from the calculated value by 0.04 mm (less than the ±0.5 mm threshold). In this case, the compensation mechanism is not triggered. If the actual displacement deviation reaches 0.55 mm, the hydraulic cylinder automatically increases the pressure to 3.5 MPa to bring the displacement back to the theoretical range. When the displacement sensor fails, the rotor automatically locks at the safety clearance position of 3.0 mm and starts the backup mechanical agitator.

[0121] The displacement system was calibrated every 24 hours: Under no-load conditions, the rotor was pushed to the zero position, and the sensor reading error was verified to be ≤0.05 mm. The load test used a slurry with a viscosity η=50 centipoise, and the hydraulic pressure was increased to P=0.5×50+10=35 MPa, while the base pressure of the compensation chamber was maintained at 10.2 MPa. The test showed a maximum axial displacement deviation of 0.35 mm, and the fatigue deformation of the spring assembly was less than 0.1 mm / 1000 cycles.

[0122] The carboxymethyl cellulose solution should be replaced every 200 hours. During replacement, the compensation chamber should be cleaned and the sealing surface should be inspected for wear. The spring assembly preload should be retested every 500 hours; if the attenuation exceeds 5%, the disc spring should be replaced. The safety valve setting pressure is 1.5 times the maximum working pressure, i.e., 52.5 MPa.

[0123] When the displacement sensor or hydraulic system fails: the rotor automatically returns to a safe position (gap 3.0 mm); a backup mechanical agitator is activated to maintain slurry treatment; an audible and visual alarm is triggered, and the grouting operation is suspended. Compared to a rigid gap structure, this implementation avoids 12 gap overload accidents in the treatment of injection molding grade ultrafine slurry (D95≤15μm). The fluid damping of the compensation chamber reduces the peak hydraulic shock pressure by 30%, and the displacement closed-loop control accuracy reaches ±0.3 mm.

[0124] Example:

[0125] Project Overview: This project involves a ventilation shaft in a mining area, with a depth of 40 meters and a diameter of 5 meters. The geological strata, from top to bottom, consist of: 0-15 meters of fine silt (permeability coefficient K=48 mD), 15-25 meters of gravel (K=120 mD), and 25-40 meters of strongly weathered mudstone. The groundwater level is 3 meters deep, and the measured water pressure in the sand layers is 1.8-2.0 MPa.

[0126] Construction process

[0127] Phase 1 (0-10 meters)

[0128] 1. Excavation and support

[0129] The excavation depth is 10 meters, and the verticality deviation of the surrounding rock of the shaft is controlled within ±25 mm.

[0130] Install the first section of C40 precast concrete curved slab (1.2×1.5 meters per slab);

[0131] Weld Q235B ring-shaped waterstop steel plate (ring width 400 mm, thickness 25 mm).

[0132] 2. Grouting operation

[0133] Pre-embedded grouting pipes are used to inject cement-water glass dual-liquid grout (PO 42.5 cement: 35Be water glass = 1:0.4 volume ratio);

[0134] The initial grouting pressure was 2.16 MPa (1.2 times the water pressure, 1.8 MPa), and the grouting depth was 0.6 m per injection. 3 Increase pressure by 0.36 MPa;

[0135] A total of 3.5 m of grouting was performed. 3 The pump stops when the pressure reaches 3.2 MPa.

[0136] 3. Ground pre-reinforcement

[0137] After the grout strength reaches 2.6 MPa (18 hours of curing).

[0138] Drive a 42 mm perforated pipe (12° inclination, 6 meters long) 40 cm outside the bottom outline of the well.

[0139] Inject ultrafine cement-water glass quick-setting grout (gel time 6 seconds) to form a 320 mm thick reinforced shell.

[0140] Second stage (10-40 meters)

[0141] 4. Application of baffle systems

[0142] Install 8 Q345B curved steel plates (600 mm high), and use φ22 mm threaded steel for the bottom anchor rod (anchoring depth 1.0 m).

[0143] Layered excavation (5 meters per section), with a 60 mm hydraulic retractable baffle system for every 1 meter of excavation depth;

[0144] The interlock controller measured a maximum pressure difference of 1.3 MPa between adjacent cylinders (threshold 1.2 MPa), and automatically adjusted the flow rate to reduce the pressure difference to 0.8 MPa.

[0145] 5. Dynamic grouting control

[0146] During gravel layer grouting, the grout viscosity was monitored by an online rheometer, η=28 cP (target η0=0.02×120+30=32.4cP).

[0147] After adding 3.2% sodium bentonite and processing in a high-speed mixing tank (1000 rpm) for 100 seconds, the viscosity increased to 31.5 cP.

[0148] The gap between the two-stage mixers was adjusted to 1.8 mm (when the viscosity η=50 cP, the hydraulic pressure P=0.5×50+10=35MPa, and η is monitored in real time by an online rheometer).

[0149] With a rotor diameter of 100 mm and a measured ΔP = 0.08 MPa, F 浆 =628 N, ΔL=6.16 mm.

[0150] 6. Sealing and Connection

[0151] The arc plate flange connection of the well wall uses M20 bolts (torque 300 N·m), and there is no leakage after a water pressure test of 0.5 MPa for 10 minutes;

[0152] The rotor displacement sensor measured ΔL = 6.2 mm (calculated value 6.16 mm), with a deviation of 0.04 mm, and compensation was not triggered.

[0153] Table 1. Key Construction Milestones and Result Verification

[0154]

[0155] Quality Inspection

[0156] Synchronization of the baffle system: The measured displacement difference was 4.8 mm, which did not exceed the 5 mm threshold (threshold 5 mm).

[0157] Grouting effect: Core sampling shows that the average thickness of the reinforced shell is 305 mm (design ≥ 300 mm).

[0158] Sealing system: Spring assembly preload attenuation 4.2% (tested after 500 hours, standard ≤5%);

[0159] Rotor displacement control accuracy: maximum deviation 0.35 mm (standard ≤ 0.5 mm).

[0160] Project Results: No sand inrush or roof collapse occurred during the entire construction process; the maximum wellbore convergence deformation was 7 mm. Single-cycle operation time was 46 hours (compared to 168 hours using traditional methods). Carboxymethyl cellulose solution was replaced every 200 hours, compensating for pressure fluctuations in the compensation chamber within ±0.4 MPa (set tolerance ±0.5 MPa).

[0161] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.

[0162] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for constructing vertical shafts, characterized in that, Includes the following steps: Step 1: Excavate an initial shaft section with a depth of 8 to 12 meters at the designed location of the vertical shaft; Step 2: Install the first section of the well wall arc plate circumferentially on the inner wall of the initial well section. Embed a longitudinal grouting pipe on the outer side of the first section of the well wall arc plate. The grout outlet of the grouting pipe extends to the outer surface of the first section of the well wall arc plate, and the grout inlet of the grouting pipe is located on the inner surface. Step 3: Weld the first annular water-stop steel plate circumferentially to the inner side of the bottom end of the first section of the well wall arc plate. The inner diameter of the first annular water-stop steel plate is consistent with the inner diameter of the first section of the well wall arc plate. Step 4: Inject cement-water glass grout into the annular gap outside the first section of the well wall arc plate through the grout inlet of the grouting pipe until the grout returns to the adjacent grouting pipe. The grouting pressure is 1.5 MPa to 2.5 MPa. Step 5: After the grouting body reaches a strength of 2 MPa to 3 MPa, drive a directional grouting pipe circumferentially 30 to 50 centimeters outside the current wellbore bottom outline. The length of the pipe is equal to the next excavation depth plus 1 meter, and the inclination angle is 10 to 15 degrees. Step 6: Inject a quick-setting dual grout of ultrafine cement slurry and water glass in a volume ratio of 1:0.3 to 1:0.5 into the formation through a directional grouting pipe. The gel takes 3 to 8 seconds to form a ring-shaped grouting solid with a thickness of 200 mm to 400 mm. Step 7: Remove the directional grouting pipe and install a retractable steel baffle system at the bottom of the current wellbore, consisting of multiple curved steel plates hinged together with a height of 500 mm to 800 mm. Step 8: Under the support of the baffle system, excavate the next section of the shaft to a depth of 4 to 6 meters. After each 1-meter excavation, the baffle system is simultaneously contracted to make the inner wall of the arc-shaped steel plate fit the surrounding rock of the newly excavated shaft. Step nine: Remove the baffle system and lay a 200-300 mm thick concrete cushion layer at the bottom of the excavated shaft; Step 10: Install the second section of the well wall arc plate, and weld the second annular water-stop steel plate to the inner side of its top. The top of the second section of the well wall arc plate is connected to the bottom of the first section of the well wall arc plate, so that the two annular water-stop steel plates fit tightly together. Step 11: Pressure grouting is performed through the second section of the well wall arc plate grouting pipe; Step 12: Repeat steps 5 through 11 until the designed well depth is reached.

2. The shaft construction method as described in claim 1, characterized in that, The retractable steel baffle system in step seven has a hydraulic jacking device on the inner side of its arc-shaped steel plate. The operation of the synchronous shrinkage baffle system in step eight is as follows: for every 1 meter of downward excavation, the hydraulic jacking device is activated to cause the arc-shaped steel plate to shrink radially by 50 mm to 80 mm; rubber sealing strips are installed at the joints of adjacent arc-shaped steel plates; detachable anchor bolts are installed at the bottom of the baffle system, and the anchor bolts are inserted into the pre-drilled holes in the formation at the bottom of the well to fix the position of the baffle system.

3. The shaft construction method as described in claim 2, characterized in that, Pressure sensors and flow control valves are installed on the oil circuit of the hydraulic jacking device; all pressure sensors are connected to the interlock controller, which sets the working pressure difference threshold between adjacent arc-shaped steel plate cylinders to 1.0 MPa to 1.5 MPa. When the real-time pressure difference between the cylinders of two adjacent arc-shaped steel plates exceeds the threshold, the interlock controller performs the following operations: reduces the oil inlet flow of the high-pressure side cylinder to 60% to 80% of the rated flow, while increasing the oil inlet flow of the low-pressure side cylinder to 100% to 110% of the rated flow. When the displacement difference between adjacent curved steel plates exceeds 5 mm, pressurized oil is injected into the lag cylinder to increase the pressure to 1.8 MPa to 2.2 MPa, triggering an audible and visual alarm.

4. The shaft construction method as described in claim 3, characterized in that, A high-pressure filter is connected in parallel on the main hydraulic line. The inlet of the high-pressure filter is connected to the rodless chamber of the cylinder, and the outlet is connected to the oil tank. Differential pressure sensors are installed at the inlet and outlet of the high-pressure filter. When the inlet and outlet pressure difference is greater than 0.4 MPa to 0.6 MPa, the bypass valve is opened to allow the oil to flow through the standby filter. The hydraulic cylinder piston rod is sealed with a combination of fluororubber O-rings and polyurethane seals.

5. The shaft construction method as described in claim 1, characterized in that, During the pressure grouting process in steps four and eleven, the following operations are performed: The water pressure outside the grouting section is monitored in real time by a water pressure sensor installed inside the well. The initial grouting pressure is set to 1.1 to 1.3 times the real-time water pressure. When the volume of grout injected reaches 0.5 to 0.8 cubic meters, the grouting pressure is increased to 0.1 to 0.2 times the real-time water pressure; grouting is stopped when the grouting pressure reaches 3.0 to 4.0 MPa or the grouting volume reaches the design value. The grouting material is a composite grout composed of ultrafine cement and silica fume in a mass ratio of 9:1 to 8:2, with a water-cement ratio of 0.6 to 0.

8.

6. The shaft construction method as described in claim 5, characterized in that, An online rheometer was installed at the outlet of the grouting pump to monitor the grout viscosity η and shear stress τ in real time. The target rheological parameters of the slurry are set as follows: viscosity η0 = 0.02 × K + 30, in cP, and shear stress τ0 = 0.15 × K + 120, where K is the formation permeability coefficient, and the value of K ranges from 10 mD to 150 mD; when K < 10 mD, it is calculated as K = 10 mD, and when K > 150 mD, it is calculated as K = 150 mD. When the real-time monitoring value η deviates from η0 by more than ±15% or τ deviates from τ0 by more than ±20%, perform the following operations: If η > 1.15η0, add water-reducing agent to the slurry to increase the water-cement ratio by 0.05 to 0.1; If η < 0.85η0, add bentonite to the slurry to increase the solid content by 3% to 5%; After adjustment, let stand and stir for 3 to 5 minutes, then monitor again until the rheological parameters meet the standards.

7. The shaft construction method as described in claim 6, characterized in that, A grout pretreatment unit is installed before the grouting pump inlet. This unit includes a high-speed mixing tank with a mixing speed of 800 to 1200 rpm. After adding bentonite or water-reducing agent to the slurry, the slurry is processed in a high-speed mixing tank for 90 to 120 seconds. The pretreated slurry is filtered through an 80-100 mesh filter before entering the grouting pump.

8. The shaft construction method as described in claim 7, characterized in that, A two-stage slurry mixer is installed inside the high-speed mixing tank; the two-stage slurry mixer includes: The first-stage spiral premixing unit consists of 6 to 8 fixed spiral blades evenly distributed around the circumference, with a blade inclination angle of 45 to 60 degrees, and is installed below the feed inlet of the mixing tank. The second-stage shear control unit includes a rotor coaxially mounted at the end of the stirring shaft and a stator fixed to the inner wall of the tank. The rotor has a trapezoidal groove with a depth of 3 mm to 5 mm on its surface, and the inner wall of the stator is provided with axial ribs. Gap adjustment mechanism: The rotor is connected to the stirring shaft through a hydraulic cylinder. The hydraulic cylinder pressure P and the real-time viscosity η of the slurry satisfy the following relationship: P=0.5×η+10; where η is calibrated in real time by an online viscosity sensor; when the calculated value of P exceeds 100MPa, the pressure is limited to 100MPa; the rotor is driven to move axially, so that the gap between the rotor and the stator is maintained within the range of 0.5 mm to 3.0 mm.

9. The shaft construction method as described in claim 8, characterized in that, In the gap adjustment mechanism: A preloaded disc spring assembly is coaxially connected to the back of the rotor. The spring assembly stiffness coefficient is 50 N / mm to 80 N / mm, and the pre-compression is 30% to 40% of the total stroke. A double-acting compensation chamber is formed between the rotor and the piston rod of the hydraulic cylinder. The upper chamber of this compensation chamber is connected to the hydraulic system and maintains a constant pressure. P base =10±0.5MPa, the lower cavity is filled with a carboxymethyl cellulose aqueous solution with a mass fraction of 8% to 12%; The maximum axial displacement ΔL of the rotor satisfies: ΔL = (F 浆 -F 预 ) / C, where F 浆 F represents the resistance exerted by the slurry on the rotor. 浆 =ΔP×A, where ΔP is the pressure difference across the rotor, ΔP≤0.5MPa, and A is the effective bearing area of ​​the rotor, 0.005 m². 2 ≤A≤0.01m 2 Fpre is the spring preload. 预 =C×δ, where δ is the pre-compression amount in millimeters, and C is the spring stiffness coefficient; the rotor is equipped with an axial displacement sensor to monitor Δ in real time. L Actual value; when Δ L When the deviation between the actual value and the calculated value exceeds ±0.5mm, the hydraulic cylinder automatically compensates for the pressure Δ. L The range of regression theoretical values.

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