Construction method for removing cutterhead mud cake by sodium percarbonate

Abstract

The application discloses a construction method for removing mud cake of a cutter head by sodium peroxycarbonate, and comprises the following steps: (1) cleaning a bentonite box and a bentonite grouting pipeline of a shield machine; (2) configuring a sodium peroxycarbonate aqueous solution, and feeding the sodium peroxycarbonate aqueous solution into the bentonite box; (3) injecting the sodium peroxycarbonate aqueous solution in the bentonite box into a gap between a cutter head panel and a working face of the shield machine and / or a soil bin of the shield machine through the bentonite grouting pipeline to remove the mud cake. The sodium peroxycarbonate is easily soluble in water and is dissociated into sodium carbonate and hydrogen peroxide, and reacts with silicates and other main mineral components of the muck to destroy the original mineral components in the mud cake, so that the muck has good compressibility and low cohesion, and the mud cake consolidation gradually dissolves.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of shield construction, in particular to a construction method for removing mud cake on cutter head by sodium carbonate peroxide. BACKGROUND

[0002] Shield construction method is widely used in urban and intercity rail transit engineering, and various studies on improving the tunneling efficiency are numerous. Among them, the mud cake on the cutter head of the shield is a phenomenon that the cuttings cut down by the cutter head are retained between the cutter head and the excavation face of the shield, and are generated into solid or semi-solid blocks under the extrusion action of the shield machine, and adhere to the cutter head.

[0003] The problem of mud cake on the cutter head is very prominent in mudstone, argillaceous siltstone, argillaceous sandstone and other strata, but most of the current researches on the problem of mud cake on the cutter head of the shield are carried out around the improvement of the cuttings by the foaming agent. In the process of tunneling, the foaming agent needs to be added to improve the cuttings, and the foaming effect of the foaming agent is optimized, but it is found in actual construction that once the mud cake appears on the cutter head, the mud cake will only accumulate more and more, accelerating the wear of the cutter and reducing the tunneling efficiency. Therefore, from the perspective of promoting the overall development of shield technology, it is necessary to find a new type of chemical agent which has remarkable effect, is widely applicable and is economically reasonable for removing the mud cake on the cutter head. SUMMARY

[0004] The main purpose of the present application is to provide a construction method for removing mud cake on cutter head by sodium carbonate peroxide.

[0005] To achieve the above purpose, the present application provides a construction method for removing mud cake on cutter head by sodium carbonate peroxide, which comprises the following steps:

[0006] (1) cleaning the bentonite box and bentonite grouting pipeline of the shield machine;

[0007] (2) configuring a sodium carbonate peroxide aqueous solution, and passing the sodium carbonate peroxide aqueous solution into the bentonite box;

[0008] (3) injecting the sodium carbonate peroxide aqueous solution in the bentonite box into the gap between the cutter head panel and the working face of the shield machine and / or the soil chamber of the shield machine through the bentonite grouting pipeline to remove the mud cake.

[0009] Further, the concentration of the sodium carbonate peroxide aqueous solution is 5%.

[0010] Further, step (3) is divided into two working conditions, and the operation method of each working condition is:

[0011] Mud cake removal working condition after normal advancing is completed:

[0012] After normal advancing is completed, when the cutter head or the roller cutter cutter box of the shield machine is caked with mud, the sodium carbonate peroxide aqueous solution is injected into the gap between the cutter head panel and the working face, and when the soil bin of the shield machine is caked with mud, the sodium carbonate peroxide aqueous solution is injected into the soil bin, after the sodium carbonate peroxide aqueous solution is injected, the segment is assembled, and the cutter head is rotated and stirred during the segment assembly period;

[0013] In this working condition, for the clay stratum, mudstone, argillaceous siltstone, argillaceous sandstone, fully weathered and strongly weathered rock stratum and other strata prone to mud cake, the mud cake can be removed during the segment assembly time (generally 30-50 min), which does not affect the normal construction organization and facilitates construction, and can effectively prevent and decompose the mud cake on the cutter head;

[0014] After the cutter replacement is completed, the mud cake is removed in the working condition:

[0015] After the cutter replacement is completed, the sodium carbonate peroxide aqueous solution is injected into the gap between the cutter head panel and the working face and / or the soil bin, and the soaking and rotating and stirring treatment is performed once or more.

[0016] In this working condition, for the stratum, the composite clay mud film is often established on the working face before the cutter replacement under pressure, and the sticky mud film becomes mud cake and is attached to the cutter head opening and the four sides of the roller cutter cutter box under the high temperature and high pressure environment, which can effectively avoid the transformation of the mud film material on the working face into mud cake.

[0017] Further, in the mud cake removal working condition after normal advancing is completed, the sodium carbonate peroxide aqueous solution is injected at 5% of the soil bin volume.

[0018] Further, in the mud cake removal working condition after the cutter replacement is completed, the sodium carbonate peroxide aqueous solution is injected at 10% of the soil bin volume.

[0019] Further, in the mud cake removal working condition after normal advancing is completed, the rotating speed of the cutter head is 0.5 revolutions per minute.

[0020] Further, in the mud cake removal working condition after the cutter replacement is completed, the soaking and rotating and stirring treatment is performed three times, the soaking time is 30 minutes each time, the rotating and stirring time of the cutter head is 10 minutes, and the rotating speed is 0.5 revolutions per minute.

[0021] Further, the specific process of configuring the sodium carbonate peroxide aqueous solution is that the sodium carbonate peroxide is added to water, and then stirred and dissolved, the stirring speed is not more than 1.5 revolutions per minute, and the stirring time is not more than 1 hour. In order to prevent the sodium carbonate peroxide from decomposing too early, the stirring is performed at this low speed and for a short time, and high speed or long time stirring is strictly prohibited.

[0022] The on-site configured sodium carbonate peroxide aqueous solution is used in time, used up at one time, and the storage time should not be more than 12 hours. Any chemical agent inevitably has corrosiveness, and before the sodium carbonate peroxide solution is injected into the bubble bin, the amount of sealing grease is injected to the main bearing seal, the pressure value of the inner and outer peripheral sealing grease cavities is ensured, and the damage of the sodium carbonate peroxide solution to the main bearing seal caused by long-term use is prevented. After the sodium carbonate peroxide solution removes the mud cake, if the bentonite system is not used for a long time, water or mud is used for cleaning to prevent the sodium carbonate peroxide from blocking the pipeline or the long-term storage of the salt from causing corrosion to the pipeline.

[0023] Sodium carbonate peroxide (2Na2CO3·3H2O2) is easily soluble in water and is dissociated into sodium carbonate and hydrogen peroxide, and reacts with silicates and other main mineral components of the sludge, destroys the original mineral components in the mud cake, and makes the sludge have good compressibility and low cohesion, and the mud cake consolidation body gradually dissolves.

[0024] During the shield construction, after each ring of the shield machine is pushed in the easy mud cake formation stratum, the sodium carbonate peroxide solution is injected into the soil bin during the segment assembly time, which can reduce the temperature in the bin in time, avoid high temperature from accelerating the production of mud cake, remove small mud cake in time, avoid the formation of large area mud cake, and prevent the generation of mud cake.

[0025] The beneficial effects of the present application are embodied in:

[0026] (1) The construction process operation is convenient, the sodium carbonate peroxide is directly added in the bentonite box of the shield machine according to the designed proportion for dissolution, and then can be put into use, without the need to increase equipment or personnel, and without the need to specially transform the equipment.

[0027] (2) The application range is wide for different strata, and the generation and removal of mud cake can be effectively prevented for various easy mud cake formation strata (such as plastic or hard plastic clay strata, mudstone, argillaceous siltstone, argillaceous sandstone, fully weathered and strongly weathered rock strata, etc.), which shows stable effect and does not have obvious difference due to different strata.

[0028] (3) The mud cake formed on the cutter head is dissolved, and the risk of manual cleaning is reduced. When the traditional foam agent and other modified sludge are used, once the mud cake is formed on the cutter head, the mud cake will be more and more, and the formed mud cake cannot be removed. The sodium carbonate peroxide solution used in the present method can effectively remove the formed mud cake in addition to preventing the generation of mud cake, which reduces the influence of manual cleaning on the construction.

[0029] (4) the adopted sodium carbonate peroxide material is high in safety and easy to store. The sodium carbonate peroxide is cheap, widely available and low in price, and is high in safety and non-toxic and harmless in use, and has no special requirement on the operating environment and no damage to the shield equipment, and is easy to store and has no change in material performance after being stacked on site. The hydrogen peroxide solution is unstable in property, and has high requirement on ground and in-hole transportation and poor environmental adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a mud cake treatment specification photo in the embodiment 2 of the present application.

[0031] Figure 2 It is a mud cake decomposition effect comparison chart of different concentrations of sodium carbonate peroxide aqueous solution in the embodiment 2 of the present application.

[0032] Figure 3 It is a mud cake decomposition effect comparison chart of water, oxalic acid and sodium carbonate peroxide aqueous solution in the embodiment 2 of the present application.

[0033] Figure 4 It is a mud cake decomposition effect comparison chart of different concentrations of sodium carbonate peroxide aqueous solution at different temperatures in the embodiment 2 of the present application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions. For example, "A and / or B" includes A solution, or B solution, or A and B solution.

[0035] Embodiment 1

[0036] The construction method of the sodium carbonate peroxide for removing the cutter head mud cake comprises the following steps:

[0037] (1) The bentonite box and the bentonite grouting pipeline of the shield machine are cleaned to ensure that the pipeline is unobstructed and the spray outlet is not blocked.

[0038] The existing shield machine is generally provided with a bentonite box and a bentonite grouting pipeline connected thereto, which is used for injecting bentonite into the soil bin and other positions to achieve soil improvement. The bentonite grouting system is used to inject the sodium carbonate peroxide aqueous solution, which is convenient to operate and does not increase additional structure.

[0039] (2) The sodium carbonate peroxide is added to the water, stirred for 50 minutes under the condition of 1.5 revolutions per minute, and a sodium carbonate peroxide aqueous solution with a concentration of 5% is configured, and then introduced into the bentonite box.

[0040] (3) Through the bentonite grouting pipeline, the sodium carbonate peroxide aqueous solution in the bentonite box is injected into the gap between the cutter head panel of the shield machine and the working face and / or the soil chamber of the shield machine to remove the mud cake;

[0041] Step (3) is divided into two working conditions, and the operation method of each working condition is as follows:

[0042] Mud cake removal working condition after normal advancing is completed:

[0043] After normal advancing is completed, when the cutter head or the cutter box of the shield machine is caked with mud, the sodium carbonate peroxide aqueous solution is injected into the gap between the cutter head panel and the working face, and when the soil chamber of the shield machine is caked with mud, the sodium carbonate peroxide aqueous solution is injected into the soil chamber. According to the situation, the sodium carbonate peroxide aqueous solution can be injected into any one or both places at the same time, and no matter what the situation is, the total amount of the sodium carbonate peroxide aqueous solution injected is 5% of the volume of the soil chamber. After the sodium carbonate peroxide aqueous solution is injected, the segment is assembled, and the cutter head is rotated at a speed of 0.5 revolutions per minute for stirring treatment within 30 minutes of segment assembly;

[0044] Mud cake removal working condition after cutter replacement is completed:

[0045] After the cutter replacement is completed, the sodium carbonate peroxide aqueous solution is injected into the gap between the cutter head panel and the working face and / or the soil chamber at 10% of the volume of the soil chamber, and the cutter head is rotated for stirring treatment three times after soaking, with a soaking time of 30 minutes each time, a cutter head rotating time of 10 minutes, and a rotating speed of 0.5 revolutions per minute.

[0046] Example 2

[0047] Effect test of sodium carbonate peroxide ablation mud cake

[0048] The experimental method is as follows:

[0049] (1) First, a piece of mud cake is taken from the same position of the cutter head or the soil chamber, and is processed into multiple pieces of the same size for standby, as shown in the following Figure 1 .

[0050] (2) The solution is configured with a concentration of 5% as the initial reference value, and an equal amount of solutions with concentrations of 2% and 7% are configured for comparison.

[0051] (3) The mud cake decomposition test is carried out, the decomposition efficiency of mud cake by sodium carbonate peroxide solutions with different concentrations is compared, and the decomposition efficiency of mud cake by 5% sodium carbonate peroxide solution is compared with water and oxalic acid solution. At the same time, the influence of temperature on mud cake decomposition is considered, and a mud cake decomposition efficiency column chart is drawn, as shown in Figures 2 to 4 , and the optimal ratio is determined by comparison.

[0052] From Figure 1 and Figure 4It can be concluded that the temperature has little effect on the decomposition effect, and good results can be obtained at room temperature during construction. The effect of a 5% sodium percarbonate solution on preventing and decomposing mud cakes has met the construction requirements. High concentration will increase the amount of sodium percarbonate, increase the cost, and high-concentration solutions may also erode the shield mud system. The effect of sodium percarbonate solution is much better than water, and basically achieves the effect of 10% oxalic acid treatment. Oxalic acid is not suitable for use in shield equipment due to its strong corrosion.

[0053] Application Example

[0054] I. Guangzhou-South to Dashi Station Intercity Tunnel of Guangfo Ring Line GFHD-1

[0055] (1) Project Overview

[0056] The uplink of Guangzhou-South to Dashi Station Intercity Tunnel is 4998.675m, and the combined ring is 2777. The downlink is 5061.157m, and the combined ring is 2811. The total length is 10059.832m. The buried depth of the inter-tunnel is 16.3m to 94m, with an average buried depth of 46m. The maximum longitudinal slope is 22‰, and the minimum longitudinal slope is 2‰. The outer diameter of the segment is 8.8m, and the ring width is 1.8m. The inter-tunnel mainly passes through strongly and moderately weathered argillaceous sandstone, and fully and strongly weathered monzonitic granite. Among them, the strongly and moderately weathered argillaceous sandstone, and the fully and strongly weathered monzonitic granite are all easy to form mud cakes during shield tunneling, with a total length of 5496m, accounting for 54.6% of the total length of the inter-tunnel.

[0057] (2) Construction and Actual Effect

[0058] The two shields of Guangzhou-South to Dashi Station Intercity Tunnel were launched on June 30, 2018 and December 13, 2018, respectively. After launching, the tunneling stratum was fully and strongly weathered argillaceous sandstone. After tunneling 650m, it gradually entered fully, strongly, and moderately weathered argillaceous sandstone.

[0059] The average buried depth of the inter-tunnel is 46m, and the maximum buried depth is 94m. The shield tunnels through fully and strongly weathered argillaceous sandstone, densely overpasses and underpasses buildings, and uses the full soil pressure mode for tunneling, with soil chamber pressure exceeding 2.5Bar. After tunneling more than 50m, the thrust increases and the speed decreases, and the measured screw machine outlet soil temperature exceeds 40℃, indicating that the soil chamber is caked. Surface grouting reinforcement was immediately carried out, and after opening the chamber for inspection, a large amount of mud cake was found in the center of the cutter head and the soil chamber wall, which was removed manually.

[0060] In the subsequent advance, the improvement of foaming agent on the slag soil was strengthened, the foaming effect of the foam was adjusted to good effect, and the injection amount of the foam was increased, and the use amount of the foam stock solution was 250-300L per ring. The parameter change during the advance is improved compared with the previous period, but the mud cake problem appears again after advancing 80-90m. And the pressure changing tool needs to establish a composite clay film on the working face. After the advance, the sticky film with high viscosity under high temperature and high pressure environment becomes mud cake attached to the opening of the cutter head and the four sides of the cutter box. The efficiency of cleaning mud cake under pressure is low, the cost is high, the normal process conversion is greatly affected, and the construction period is delayed.

[0061] After the project, the construction method of Example 1 was used to remove the mud cake under the working condition of removing the mud cake after the normal advance and the working condition of removing the mud cake after the tool change, and the sodium peroxide aqueous solution was injected into the gap between the cutter head panel and the working face and the soil chamber to remove the mud cake, which achieved good results. The cutter head did not appear mud cake problem affecting the advance, and the same effect was achieved in the subsequent mudstone, whole, and strongly weathered monzonitic granite strata. It not only saves the construction period, but also saves the cost, reduces the risk of opening inspection, and achieves excellent comprehensive benefits.

[0062] II. Hangzhou West Station-Central Park Station Section of Hangzhou Airport Express Line

[0063] (1) Project Overview

[0064] The Hangzhou West Station-Central Park Station section is a double-line single circular shield section. The design start and end mileage of the tunnel is: right line K6+357.921-K8+654.837, with a long chain of 2.171m at right K8+032.171, and the total length of the right line section is 2299.087m; left line K6+357.923-K8+656.929, with a short chain of 28.682m at left K8+021.318, and the total length of the left line section is 2270.324m.

[0065] The main stratum of the shield starting section is sandy silt, silt clay, clay, and silty clay. The main stratum of the receiving section is silty clay with silt and clay. The geological conditions of the normal section are as follows: the tunnel mainly passes through ⑤2 silty clay with silt, ⑤3 sandy silt, ⑥1 silt clay, ⑦1 clay, ⑧2 silty clay, ⑨1 silty clay, ⑩1 silty clay, 1 fine sand, 4 round gravel, 2 silty clay.

[0066] (2) Construction and Actual Effect

[0067] During the process of shield construction, the problem of mud cake formed on the cutter head in the clay stratum is often encountered. The main strata where the mud cake is formed on the cutter head include weathered (full and medium) mudstone, argillaceous siltstone, argillaceous sandstone, silt, mucky clay and silty clay. It is a phenomenon that the cuttings cut down by the cutter head are retained between the cutter head and the shield excavation face, and form solid or semi-solid block materials by the repeated extrusion and friction of the cutter head, and adhere to the cutter head. When the mud cake is formed on the cutter head of the shield, the cutters on the cutter head will be gradually covered by the consolidated clay, resulting in the decrease of the cutter penetration when the cutter head cuts the stratum. When the cutters and the cutter head opening are completely covered by the mud cake, the tunneling speed will be greatly reduced, and the phenomena of large thrust, large cutter head torque, high cutting temperature and the like will occur, and the controllability of the tunneling risk will be greatly reduced, which will cause great threat to the safety of the equipment. At this time, measures need to be taken to remove the mud cake on the cutter head and increase the opening rate. When the mud cake is serious, the traditional method of opening the chamber under pressure is used for manual cleaning, which takes a long time and has great construction risk.

[0068] The construction method of Example 1 is used in the project, and the mud cake removal condition treatment after normal advancing and the mud cake removal condition treatment after cutter replacement are implemented, and sodium percarbonate aqueous solution is injected into the gap between the cutter head panel and the working face and the soil chamber to remove the mud cake, so that the mud cake on the cutter head of the shield machine in the clay stratum is quickly removed by this method. The method of removing the mud cake has the characteristics of convenience, speed, economy and high safety, and can realize the rapid tunneling in the clay stratum.

[0069] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for removing cutterhead cake using sodium percarbonate, characterized in that, Includes the following steps: (1) Clean the bentonite box and bentonite grouting pipeline of the tunnel boring machine; (2) Prepare a sodium percarbonate aqueous solution with a concentration of 5%. Sodium percarbonate dissolves in water and dissociates into sodium carbonate and hydrogen peroxide, which react chemically with silicate, the main mineral component of the slag, thereby destroying the original mineral components in the mud cake and gradually dissolving the mud cake solid. The sodium percarbonate aqueous solution is then introduced into the bentonite box. (3) The sodium percarbonate aqueous solution in the bentonite box is injected into the gap between the cutterhead panel and the tunnel face and / or the soil chamber of the tunnel boring machine through the bentonite grouting pipeline to remove the mud cake; Step (3) is divided into two working conditions, and the operation method for each working condition is as follows: After normal tunneling is completed, mud cake removal is performed during the segment assembly time for tunneling in formations such as plastic clay, stiff plastic clay, mudstone, silty mudstone, sandstone, and completely weathered and strongly weathered rock. After normal progress is completed, when mud cake forms on the cutterhead or cutter box of the tunnel boring machine, sodium percarbonate aqueous solution is injected into the gap between the cutterhead panel and the working face. When mud cake forms in the soil chamber of the tunnel boring machine, sodium percarbonate aqueous solution is injected into the soil chamber. After the sodium percarbonate aqueous solution is injected, the tunnel segments are assembled, and the cutterhead is rotated to stir during the segment assembly. After the cutterhead replacement is completed, the mud cake is removed. For through formations, before the pressurized cutterhead replacement, a composite clay mud film needs to be established on the working face. After subsequent advancement, the highly viscous mud film will turn into mud cake under high temperature and high pressure, adhering to the cutterhead opening and the area around the cutter head box. After the cutter is changed, inject sodium percarbonate aqueous solution into the gap between the cutter head panel and the working face and / or into the soil chamber, and perform soaking and stirring treatment once or more by rotating the cutter head to prevent the mud film material on the working face from turning into mud cake. After the normal progress is completed and the mud cake is removed, inject sodium percarbonate aqueous solution at 5% of the soil chamber volume; After the cutter is replaced and the mud cake is removed, inject sodium percarbonate solution at 10% of the soil chamber volume.

2. The method for removing cutter cake from a cutting disc using sodium percarbonate as described in claim 1, characterized in that, After normal propulsion is completed and the mud cake is removed, the rotation speed of the cutter head is 0.5 revolutions per minute.

3. The method for removing cutter cake from a cutting disc using sodium percarbonate as described in claim 1, characterized in that, After the blade was changed and the mud cake was removed, a total of three soaking and rotating blade disc agitation processes were performed. Each soaking time was 30 minutes, and the rotating blade disc time was 10 minutes, with a rotation speed of 0.5 rpm.

4. The method for removing cutter cake from a cutting disc using sodium percarbonate as described in claim 1 or 2, characterized in that, The specific process for preparing sodium percarbonate aqueous solution is as follows: add sodium percarbonate to water, then stir to dissolve it. The stirring speed should not exceed 1.5 rpm, and the stirring time should not exceed 1 hour.

Images