Construction method for preparing synchronous double slurry by using shield tunneling mud

Abstract

The present application relates to the technical field of shield tunnel construction, and discloses a construction method for preparing synchronous double-liquid slurry by using shield tunneling mud, which comprises the following steps: preparing mud which meets the requirements of shield tunneling and synchronous grouting; introducing the mud into a cement-soil slurry mixing station on a supporting trolley behind a shield tunneling machine; storing the prepared main slurry in a main slurry storage tank; when synchronous grouting is performed, using a coaxial ring generator to flow together the main slurry and lubricating mud to form double-layer coaxial slurry, and pumping the double-layer coaxial slurry to a mixer, mixing the double-layer coaxial slurry with water glass, and then injecting the mixture into a shield tail gap. The present application not only solves the problem of difficult transportation in the whole process from slurry preparation to grouting by using waste mud to prepare synchronous double-liquid slurry, but also can treat the waste mud into mud which meets the requirements of shield tunneling and synchronous double-liquid grouting, and efficiently transport the mud into a tunnel through a slurry inlet pipe. Meanwhile, the present application can optimize the grouting pipeline to solve the problem of pipe blockage caused by the slurry prepared by the waste mud.

Description

Technical Field

[0001] This invention relates to the field of shield tunnel construction technology, and more specifically, to a construction method for preparing synchronous dual-liquid slurry using shield tunneling mud. Background Technology

[0002] Shield tunneling is one of the commonly used construction methods for tunnels. During shield tunneling, the gap between the shield tail strata and the tunnel segments needs to be filled with grout, a process known as synchronous grouting. Synchronous grouting materials include single-component and double-component grouts; in recent years, cement-water glass double-component grout has become the more common choice for large-diameter shield tunnels, replacing single-component grout. Slurry-balanced shield tunneling machines are the most widely used type for large-diameter shield tunnel construction in China. These machines balance the water and soil pressure at the tunnel face using slurry. The slurry is a mixture of water, clay, and additives, and also serves to transport excavated soil and cool and lubricate the cutterhead. The shield tunneling machine is equipped with a slurry transport system and a surface slurry station. Before the shield starts, sufficient slurry is prepared and stored. After starting, the slurry inlet pipe of the transport system transports the slurry to the tunnel face. The slurry, carrying excavated soil, travels through the slurry outlet pipe to the surface slurry station for slurry-water separation, removing large-diameter excavated soil, and then using a portion of the slurry to prepare qualified slurry before it is transported back to the tunnel face. However, the remaining large amount of mud is waste slurry, which, after dewatering by pressure filtration, becomes slag, which is then transported off-site for disposal or recycled. Currently, there is research on materials for preparing single-liquid or two-liquid slurries from waste mud or slag, but in practical engineering, convenient and efficient construction methods are still lacking.

[0003] For conventional slurry shield tunneling projects, when using dual-liquid grout as the synchronous grouting material, supporting ground facilities and sites such as a slurry station and an A-liquid (cement slurry) mixing station are essential and independent. During shield tunneling, slurry produced at the slurry station is transported to the tunnel face through the slurry inlet pipe, and then slurry containing excavated soil is transported back to the slurry station for processing through the slurry outlet pipe. A-liquid produced at the A-liquid mixing station is delivered to the shield machine via pump trucks or pipelines, and then injected into the gap between the shield tail segments and the ground through the synchronous grouting system. Currently, the A-liquid component of synchronous dual-liquid grout mainly consists of cement, bentonite, stabilizer, and water. Cement is a non-renewable resource, and its production process consumes a large amount of energy. Bentonite requires multiple treatment, processing, and modification processes to produce. To reduce the amount of cement and bentonite used, research is being conducted on using industrial waste and engineering solid waste (including waste slurry and excavated soil generated during slurry shield tunneling) as substitutes.

[0004] However, current methods for preparing synchronous grouting materials from waste mud or slag in the industry, including those already applied and conceptual ones, all involve treating the waste mud or slag on the ground using various methods to produce grouting materials before transporting them into the tunnel. These methods have the following defects or shortcomings:

[0005] 1) The process of recycling waste mud is complex. Existing technologies require separate treatment of waste mud to obtain raw materials that meet the requirements of synchronous grouting. It also requires the addition of a transportation link between the mud treatment site and the grouting material production site, which greatly increases the construction process, equipment and cost.

[0006] 2) Because the soil particles in waste mud or slag are unstable in properties and gradation, and contain a large number of ions commonly found in groundwater, the grout prepared from them is more prone to bleeding during transportation. Long-distance transportation will make it more difficult to guarantee the quality of the grout, which is not conducive to the quality control of grouting.

[0007] 3) The addition of waste mud increases the solid content of the synchronous grout, reduces its fluidity, and increases its viscosity. During grouting, the grout is more likely to adhere to the pipe wall, exacerbating the pipe blockage problem that already exists in synchronous grouting.

[0008] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0009] To address the problems in related technologies, this invention proposes a construction method for preparing synchronous dual-liquid slurry using shield tunneling mud, thereby overcoming the aforementioned technical problems existing in the prior art.

[0010] Therefore, the specific technical solution adopted by the present invention is as follows:

[0011] A construction method for preparing synchronous two-component slurry using shield tunneling mud includes:

[0012] S1. Through mix proportion tests, determine the mud index and mix proportion that simultaneously meet the requirements of shield tunneling and synchronous grouting, and prepare mud that simultaneously meets the requirements of both application conditions.

[0013] The mix proportions include the mix proportions of cement slurry and water glass, the mix proportions of lubricating mud and main slurry in cement slurry, and the mix proportions of mud, retarder and cement in main slurry.

[0014] S2. The prepared mud slurry is pumped into the tunnel through the slurry inlet pipe, and the mud slurry is introduced into the cement-soil slurry mixing station on the trolley behind the shield machine through the slurry preparation branch pipe.

[0015] S3. Based on the mixing ratio of lubricating mud and main slurry, extract the corresponding mass of mud from the mud tank in the cement-soil slurry mixing plant as lubricating mud; based on the mixing ratio of main slurry, add mud, retarder and cement to the main slurry mixing tank in the cement-soil slurry mixing plant in sequence and mix evenly, and store the prepared main slurry in the main slurry storage tank.

[0016] S4. During synchronous grouting, the coaxial ring generator is used to merge the main slurry and lubricating mud in the main slurry storage tank to form a double-layer coaxial slurry, so as to form a lubricating layer around the main slurry. Combined with the mixing ratio of cement-soil slurry and water glass, the double-layer coaxial slurry is pumped to the mixer to mix with water glass and then injected into the shield tail gap.

[0017] Furthermore, through mix proportion tests, the mud parameters and mix proportions that simultaneously meet the requirements of shield tunneling and synchronous grouting were determined, and mud that simultaneously meets the requirements of both application conditions was prepared, including:

[0018] S11. Based on the geological characteristics of the tunnel boring machine, determine the range of mud indexes for the tunneling mud, and combine the mud ratio test to determine the mud indexes and mix ratio required to prepare synchronous grouting slurry.

[0019] S12. Based on the determined mud index and mix ratio, prepare mud at the mud station that simultaneously meets the requirements of shield tunneling and synchronous grouting.

[0020] Furthermore, the parameters of the lubricating mud are the same as those of the mud in the main slurry, and the sum of the mass of the mud in the main slurry and the mass of the lubricating mud is equal to the mass of the mud in the cement-soil slurry.

[0021] Furthermore, several ball valves are installed on the slurry inlet pipe, and a slurry preparation branch pipe is connected to the ball valve near the cement-slurry mixing station. The slurry preparation branch pipe is equipped with a filter screen, valve and flow meter.

[0022] Furthermore, the slurry in the grout inlet pipe is used to balance the working face, carry slag, or flush, while the slurry in the grouting branch pipe is used to prepare the cement-soil slurry for synchronous grouting.

[0023] Furthermore, the cement-slurry mixing plant includes a mud tank, a main slurry mixing tank, a retarder tank, a cement tank, and a main slurry storage tank.

[0024] Furthermore, the coaxial ring generator consists of a coaxial ring and a cement-soil slurry connector that mates with it; wherein, the coaxial ring includes a main slurry connector, and the bottom end of the main slurry connector extends downward into the interior of the cement-soil slurry connector, and a matching connecting pipe is sleeved on the outside of the main slurry connector, and the bottom end of the connecting pipe is connected to the top end of the cement-soil slurry connector, and a coaxial ring cavity is formed between the inner diameter of the connecting pipe and the outer diameter of the main slurry connector, and a lubricating mud connector is provided on one side of the connecting pipe.

[0025] Furthermore, the main grout pipe, connecting pipe, and cement-soil grout pipe are coaxially arranged, and the top of the main grout pipe extends above the connecting pipe and is connected to the main grout storage tank through a pipeline.

[0026] Furthermore, the size of the coaxial annular cavity is matched with the volume ratio of the main slurry to the lubricating slurry in the cement slurry; the ratio of the net cross-sectional area of ​​the connecting pipe to the net cross-sectional area of ​​the main slurry pipe is equal to the volume ratio of the lubricating slurry to the main slurry.

[0027] Furthermore, before the first construction or before emptying the grouting pipeline and re-grouting, the mud in the mud tank is pumped to the lubricating mud connector, so that the lubricating mud enters the cement-soil grout connector and the cement-soil grouting pipeline through the coaxial annular cavity to pre-lubricate the pipeline.

[0028] The beneficial effects of this invention are as follows:

[0029] 1) This invention not only solves the transportation problem in the entire process of preparing synchronous dual-liquid grout from slurry preparation to grouting using waste mud, but also can process waste mud into grout that can simultaneously meet the requirements of shield tunneling and synchronous dual-liquid grouting, and efficiently transport it into the tunnel through the grout inlet pipe. At the same time, it can optimize the grouting pipeline to solve the problem of pipe blockage caused by grout made from waste mud.

[0030] 2) This invention can determine the mud index that meets the requirements of shield tunneling based on the geological characteristics of the tunnel boring machine, and then adjust the mixing ratio of the synchronous grouting slurry accordingly. Through this method, the mud can meet the requirements of both shield tunneling and synchronous grouting, achieving "one slurry for two purposes".

[0031] 3) This invention can directly use the mud after mud-water separation to prepare synchronous grouting slurry, which reduces the volume and cost of waste mud treatment and eliminates the need for additional waste mud treatment processes and equipment, thus effectively reducing construction costs. At the same time, for clay strata, it can also alleviate the constraint on shield tunneling speed caused by the difficulty in treating waste mud.

[0032] 4) This invention pumps the raw mud directly into the shield tunnel through the slurry inlet pipe, which not only ensures the stability of the slurry quality, but also avoids increasing the cost of transporting waste mud, and achieves efficient mud transportation.

[0033] 5) This invention directly uses mud from the grout inlet pipe to replace bentonite and water to prepare synchronous grouting slurry, which not only effectively reduces material costs but also saves the bentonite expansion process, improves the efficiency of synchronous grouting slurry preparation, and simplifies slurry preparation equipment.

[0034] 6) This invention uses a coaxial ring generator to form a double-layer coaxial grout in the cement-soil grout connector and cement-soil grouting pipeline, thereby utilizing low-viscosity mud as a drag-reducing fluid to form a lubricating layer around the main grout. Compared to directly pumping high-viscosity cement-soil grout, this invention can utilize mud, one of the raw materials, as a lubricating fluid for the grouting pipeline, reducing the residue of high-viscosity grout on the pipe wall and lowering the risk of grouting pipe blockage.

[0035] 7) The main slurry and lubricating mud slurry transported separately in this invention together form cement-soil slurry, which does not change the composition of raw materials, affect the reaction of slurry and products, and achieves the effect of reducing the risk of pipe blockage. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram illustrating the principle of a construction method for preparing synchronous dual-liquid slurry using shield tunneling mud, according to an embodiment of the present invention.

[0038] Figure 2 This is a schematic diagram of the mud preparation process in a construction method for preparing synchronous dual-liquid mud using shield tunneling mud according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of the structure of a cement-soil slurry mixing plant in a construction method for preparing synchronous dual-liquid slurry using shield tunneling mud, according to an embodiment of the present invention.

[0040] Figure 4 This is a schematic diagram of the coaxial ring generator in a construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to an embodiment of the present invention.

[0041] Figure 5 This is a schematic diagram of the coaxial ring structure in a construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to an embodiment of the present invention;

[0042] Figure 6 yes Figure 4 Cross-sectional view at point AA;

[0043] Figure 7 This is a schematic diagram of a dual-liquid grouting system in a construction method for preparing synchronous dual-liquid grout using shield tunneling mud, according to an embodiment of the present invention.

[0044] In the picture:

[0045] 1. Coaxial ring; 11. Main slurry connector; 12. Connecting pipe; 13. Coaxial ring cavity; 14. Lubricating mud connector; 2. Cement-soil slurry connector. Detailed Implementation

[0046] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0047] According to an embodiment of the present invention, a construction method for preparing synchronous dual-liquid slurry using shield tunneling mud is provided.

[0048] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments, such as... Figures 1-7 As shown, the construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to an embodiment of the present invention includes:

[0049] S1. Through mix proportion tests, determine the mud index and mix proportion that simultaneously meet the requirements of shield tunneling and synchronous grouting, and prepare mud that simultaneously meets the requirements of both application conditions.

[0050] like Figure 2 As shown, a mud station generally consists of a mud-water separation system, a mud preparation / conditioning system, and a waste mud / slag treatment system.

[0051] For the initial mud preparation before geyser launch, clay (usually bentonite), water, and necessary additives (such as flocculants, quicklime, carboxymethyl cellulose, etc.) are mixed thoroughly and a sufficient quantity is stored in the new mud tank, conditioning tank, and other tanks. During the mud preparation stage at the start of geyser launch, the mud is transported to the working face through the mud inlet pipe and fills the mud-water tank.

[0052] Once the tunnel boring machine begins excavation, the cutterhead cuts through the strata, and the excavated soil falls into the slurry. The slurry discharge pipe then sends the slurry carrying the excavated soil back to the slurry station, where it is further processed into slurry through a mud-water separation system and a slurry preparation / adjustment system.

[0053] The working process of the mud-water separation system is as follows: First, the larger sand particles and clay lumps are screened out by pre-screening equipment such as vibrating screens or drum screens; the remaining mud carrying smaller particles of slag is then passed through primary and secondary cyclone devices to remove even smaller particles of slag. The mud obtained after the secondary cyclone flows to the sedimentation tank and is left to stand in the sedimentation tank.

[0054] The slurry preparation / adjustment system operates as follows: Based on the required slurry performance and quantity for shield tunneling and synchronous grouting, an appropriate amount of slurry is taken from the sedimentation tank and transported to the slurry preparation tank to be re-adjusted to meet the performance requirements (the preparation method is to directly add water or add some new slurry, and add an appropriate amount of admixture as needed).

[0055] The prepared grout will be sent back to the tunnel face through the grout inlet pipe, and the above processes of carrying slag, separating mud and water, and preparing / mixing grout will be repeated. Synchronous grouting is only required after the shield tail of the tunnel boring machine enters the tunnel portal.

[0056] In this embodiment, the mud parameters must meet both the requirements of shield tunneling and synchronous grouting. However, the mud parameters are constantly adjusted according to the geological formation. When the mud parameters change, synchronous grouting slurry cannot be prepared directly. The mix ratio of synchronous grouting slurry needs to be adjusted accordingly to meet the functional requirements of synchronous grouting.

[0057] Specifically, through mix proportion tests, the mud parameters and mix proportions that simultaneously meet the requirements of shield tunneling and synchronous grouting were determined, and mud that simultaneously meets the requirements of both application conditions was prepared, including:

[0058] S11. Based on the geological characteristics of the tunnel boring machine, determine the range of mud indexes for the tunneling mud, and within this range, combine with mix proportion tests to determine the mud indexes and mix proportions required for preparing synchronous grouting slurry; wherein, the mix proportions include the mix proportions of cement-soil slurry and water glass, the mix proportions of lubricating mud and main slurry in cement-soil slurry, and the mix proportions of mud, retarder and cement in main slurry, and the indexes of lubricating mud are the same as those of mud in main slurry, and the sum of the mass of mud in main slurry and the mass of lubricating mud is equal to the mass of mud in cement-soil slurry;

[0059] Specifically, the parameters of tunneling mud include specific gravity, viscosity, sand content, and filtration loss, and the values ​​can be determined based on construction standards, experience, and trial tunneling.

[0060] The performance requirements of synchronous grouting slurry can be found in relevant standards or the requirements of the construction unit and design unit. Based on the required performance indicators, the mud index and the mix proportion for preparing synchronous grouting slurry are determined through mix proportion tests.

[0061] In this embodiment, the performance index range of the mud should preferably be limited to: specific gravity 1.10~1.30g / cm³. 3 The sand content does not exceed 5%. Normally, it covers all strata, so it has universal applicability.

[0062] S12. Based on the determined mud index and mix ratio, prepare mud at the mud station that simultaneously meets the requirements of shield tunneling and synchronous grouting.

[0063] In this embodiment, the core component of the synchronous grouting material used is cement-soil grout. Essential components of cement-soil grout include mud (comprising more than 60% of the total mass), cementitious materials (cement is recommended, but other cementitious materials can also be used), and a retarder (determined based on the type and performance of the retarder; when cement is used as the cementitious material, the dosage is controlled according to the mass ratio with cement; the principle for determining the dosage is to meet the setting time requirements at the construction site, generally requiring a setting time of not less than 72 hours; the dosage is related to the specific product performance and is determined based on the manufacturer's recommendations or on-site setting time testing).

[0064] In addition, this construction method can also be used if water, bentonite, mineral admixtures (fly ash, granulated blast furnace slag powder, etc.) and other additives are added to the cement slurry. The construction method is not affected by the material mix ratio.

[0065] In this embodiment, in order to reduce the amount of high-viscosity cement-soil slurry adhering to the inner wall of the grouting pipeline and thus reduce the risk of pipe blockage, the cement-soil slurry is divided into main slurry and lubricating mud (because the viscosity of the mud is much smaller than that of the cement-soil slurry, during the subsequent synchronous grouting construction, the lubricating mud forms a mud ring around the main slurry, which plays a role in lubrication and preventing blockage).

[0066] After the cement-soil slurry mix proportion is determined, the cement-soil slurry is divided into two parts: the main slurry and the lubricating mud slurry. The lubricating mud slurry is the same as the mud slurry in the cement-soil slurry and the main slurry (i.e., the lubricating mud slurry, the mud slurry in the cement-soil slurry, and the mud slurry in the main slurry are all prepared by S1), and the proportion of the lubricating mud slurry in the volume of the cement-soil slurry is 5% to 15%, and a fixed proportion can be taken for the same project; the slurry remaining after deducting the lubricating mud slurry in the cement-soil slurry is the main slurry.

[0067] S2. The prepared mud slurry is pumped into the tunnel using the slurry inlet pipe, and then introduced into the cement-soil slurry mixing station on the trolley behind the shield machine through the slurry preparation branch pipe.

[0068] Specifically, the grout inlet pipe is equipped with several ball valves, and a grouting branch pipe is connected to the ball valve near the cement-soil mixing station. The diameter of the grouting branch pipe meets the grouting requirements and is greater than or equal to 60mm. The grout inlet pipe still leads to the front of the tunnel boring machine. The slurry in the pipe is used to balance the working face, carry slag, or flush; the slurry in the grouting branch pipe is used to prepare the synchronous grouting slurry.

[0069] A filter screen is installed on the slurry branch pipe to filter out residual sand particles in the slurry (the particle size of the filter screen is determined according to the grouting pipeline, and the principle is that it can pass through all conveying pipelines, and the particle size can be controlled by 1 to 2 mm); a valve is installed on the slurry branch pipe to control the slurry entering the main slurry mixing station; a flow meter is installed on the pipeline to measure the amount of slurry entering the main slurry mixing station and control the amount of slurry to be dispensed as needed.

[0070] like Figure 3As shown, the cement-soil slurry mixing plant is installed on the supporting trolley at the rear of the tunnel boring machine. The necessary containers include a mud tank, a main slurry mixing tank, a retarder tank, a cement tank, and a main slurry storage tank. The containers can be adjusted accordingly based on the mix proportion determined in S1.

[0071] Before preparing the synchronous grouting slurry, the valve is opened to temporarily store the slurry in a slurry tank. The slurry tank is equipped with a hydrometer and a stirring device, used to test the slurry's specific gravity and to stir the slurry to prevent bleeding, respectively.

[0072] S3. Based on the mixing ratio of lubricating mud and main slurry, extract the corresponding mass of mud from the mud tank in the cement-soil mixing plant as lubricating mud; based on the mixing ratio of main slurry, add mud, retarder and cement to the main slurry mixing tank in the cement-soil mixing plant in sequence and mix evenly, and store the prepared main slurry in the main slurry storage tank.

[0073] Specifically, when pulp preparation is required, the valve between the mud tank and the main slurry mixing tank is opened, and a measured amount of mud is injected into the main slurry mixing tank. The volume of the mud is controlled by a flow meter installed at the valve. Based on the mixing ratio determined in S1, the amount of each raw material added is obtained. The order of raw material addition is as follows:

[0074] When the only raw materials are mud, retarder, and cement, firstly, an appropriate amount of mud is transported to the main slurry mixing tank; then, an appropriate amount of retarder is added according to the main slurry mix ratio and stirred evenly; finally, cement is added according to the main slurry mix ratio, and after being thoroughly stirred evenly, the main slurry is transported to the storage tank and stored therein.

[0075] When the raw materials include slurry, retarder, cement, and granulated blast furnace slag powder, firstly, an appropriate amount of slurry is transported to the main slurry mixing tank; then, an appropriate amount of retarder is added according to the main slurry mix ratio and stirred evenly; next, an appropriate amount of granulated blast furnace slag powder is added according to the main slurry mix ratio and stirred evenly; finally, cement is added according to the main slurry mix ratio, and after thorough mixing, the main slurry is transported to the slurry storage tank and stored therein.

[0076] A flow meter and a hydrometer are installed at the inlet of the main slurry storage tank to measure the volume and specific gravity of the main slurry entering the tank. A low-speed agitator is installed inside the main slurry storage tank to continuously agitate and prevent the main slurry from bleeding.

[0077] S4. During synchronous grouting, the coaxial ring generator is used to merge the main slurry and lubricating mud in the main slurry storage tank to form a double-layer coaxial slurry, so as to form a lubricating layer around the main slurry. Combined with the mixing ratio of cement-soil slurry and water glass, the double-layer coaxial slurry is pumped to the mixer to mix with water glass and then injected into the shield tail gap.

[0078] In this embodiment, a coaxial ring generator is added to the conventional synchronous grouting pipeline, and the coaxial ring generator is connected to the cement-soil grouting pipeline.

[0079] like Figures 4-6 As shown, the coaxial ring generator consists of a coaxial ring 1 and a cement-slurry slurry connector 2 that cooperates with it. The coaxial ring 1 includes a main slurry connector 11, and the bottom end of the main slurry connector 11 extends downward into the interior of the cement-slurry slurry connector 2. A connecting pipe 12 that cooperates with it is sleeved on the outside of the main slurry connector 11, and the bottom end of the connecting pipe 12 is connected to the top end of the cement-slurry slurry connector 2. A coaxial ring cavity 13 is formed between the inner diameter of the connecting pipe 12 and the outer diameter of the main slurry connector 11, and the top of the coaxial ring cavity 13 is sealed. A lubricating mud slurry connector 14 is provided on one side of the connecting pipe 12.

[0080] Specifically, the main grout connector 11, connecting pipe 12, and lubricating grout connector 14 are all made of steel and are round pipes. The cement-soil grout connector 2 is made of steel and is connected to the cement-soil grouting pipeline, with the same inner diameter as the cement-soil grouting pipeline.

[0081] The main grout connector 11, connecting pipe 12, and cement-soil grout connector 2 are coaxially arranged, with the top end of the main grout connector 11 extending above the connecting pipe 12 and connected to the main grout storage tank via a pipeline. The inner diameter of the connecting pipe 12 is slightly larger than the outer diameter of the main grout connector 11. The size of the coaxial annular cavity 13 matches the volume ratio of the main grout to the lubricating mud in the cement-soil grout. The ratio of the net cross-sectional area of ​​the connecting pipe 12 to the net cross-sectional area of ​​the main grout connector 11 is equal to the volume ratio of the lubricating mud to the main grout. The side wall opening of the connecting pipe 12 is welded to the lubricating mud connector 14, and the length l4 of the lubricating mud connector 14 is greater than or equal to 50 mm.

[0082] In this embodiment, the final mix ratio is the volume ratio. If the net cross-sectional area of ​​the lubricating mud and the main slurry is controlled to be equal to the volume ratio, then their flow rates will be the same, which is equivalent to them being relatively stationary, thus reducing disturbance to the interface. In actual construction, this can be controlled by adjusting their slurry supply rate per unit time.

[0083] The axial length l1 of the connecting pipe 12 is 100–300 mm. The main grouting pipe 11 extends beyond the top of the connecting pipe 12 by a length l2 greater than or equal to 50 mm and is connected to the main grouting storage tank via a pipe; the length of the main grouting pipe 11 extends beyond the bottom of the connecting pipe 12 and continues into the cement-soil grouting pipe 2 by a length l3 greater than or equal to 300 mm. The length of the cement-soil grouting pipe 2 is greater than or equal to the length l3 of the main grouting pipe 11 extending into the cement-soil grouting pipe 2.

[0084] like Figure 7As shown, before the initial construction or before clearing the grouting pipeline and re-grouting, the mud in the mud tank is pumped to the lubricating mud connector 14. The lubricating mud enters the cement-soil grout connector 2 and the cement-soil grouting pipeline through the coaxial annular cavity 13 to pre-lubricate the pipeline. After lubrication, the main grout in the main grout storage tank is pumped into the main grout connector 11 and the cement-soil grout connector 2 through the pipeline. When a stable coaxial grout is formed, it is then injected into the shield tail through the cement-soil grouting pipeline. The pre-lubricated mud and the unstable grout are discharged through the pipeline and do not enter the shield tail. During grouting, the mixing ratio of cement-soil grout is ensured by controlling the injection volume of the main grout and the lubricating mud. The ratio of the main grout injection volume to the lubricating mud injection volume is equal to the ratio of the main grout volume to the lubricating mud volume.

[0085] When using a two-component grout, the cement-soil grout and water glass solution are mixed in a mixer at a suitable location from the shield tail and then injected into the shield tail gap.

[0086] Furthermore, when using single-liquid grout construction, the above-mentioned construction method of the present invention can also be used, wherein the grout mainly replaces the bentonite and water in the grouting material.

[0087] Furthermore, to facilitate understanding of the above-mentioned technical solutions of the present invention, the construction method of the present invention will be described in detail below using a certain cross-river tunnel project as an example.

[0088] Step 1: When located in silty sand or clay strata, the specific gravity of the drilling mud can be 1.15–1.2 g / cm³ to meet the tunneling requirements. 3 The viscosity can be taken as 18-19s. This project uses a two-component grout as the synchronous grouting material, that is, cement-soil grout and water glass are mixed to form the grout body. The main focus of the synchronous grouting is the specific gravity of the mud, which should be between 1.15 and 1.25 g / cm³. 3 Within the specified range, through on-site mix proportion tests, the optimal concentration of 1.2 g / cm³ was determined. 3 The mud used had a water glass specific gravity of 1.37 g / cm³. 3 The mixing ratio of synchronous grout (cement-soil grout + water glass) per cubic meter is shown in Table 1 below:

[0089] Table 1. Mix proportion of synchronous grout (cement-soil grout + water glass) per cubic meter

[0090] The specific gravity of the cement-soil slurry under this mix proportion is 1.369 g / cm³. 3 The 3-hour bleeding rate was 1.8%, the gel time after mixing cement slurry and water glass was 12.5 seconds, the 1-day strength was 0.98 MPa, and the 28-day strength was 2.08 MPa, all of which met the requirements of the standards, the construction unit, and the construction.

[0091] In the above proportions, the volume of water glass is 0.06 cm³.3 The volume of the cement-soil slurry is 0.94 cm³. 3 If 9.5% of the cement-soil slurry volume (i.e., the ratio of main slurry to lubricating slurry volume is 9.5) is taken as the lubricating slurry, then the volume of the lubricating slurry is 0.089 m³. 3 , at 1.2g / cm 3 The calculated mass of the lubricating mud is 107.2 kg. Therefore, the mixing ratio of the lubricating mud and the main slurry is shown in Table 2 below:

[0092] Table 2. Mixing ratio of lubricating mud to main slurry

[0093] In Table 2, the mass of lubricating mud (107.2 kg) and the mass of mud in the main slurry (933.6 kg) add up to 1040.8 kg. Therefore, mixing the main slurry and lubricating mud to obtain cement-soil slurry does not change the mix proportion and reaction products.

[0094] Step 2: Install a cement-soil slurry mixing station on the supporting trolley behind the tunnel boring machine. Multiple ball valves are pre-installed on the slurry inlet pipe (DN500). Connect a slurry branch pipe (DN100) to the ball valve near the cement-soil slurry mixing station. Install a 1mm filter screen near the ball valve to remove any sand particles larger than 1mm that may remain.

[0095] This project includes two cement-soil slurry mixing systems (i.e., cement-soil slurry mixing plants), consisting of two slurry tanks (each with a capacity of 4m³). 3 ), two retarder tanks (each with a capacity of 1m³) 3 ), Cement silos *2 (each with a capacity of 20m³) 3 ), two main impeller mixing tanks (each with a capacity of 2m³). 3 ) and two main slurry storage tanks (each with a capacity of 30m³) 3 It consists of two sets of cement-soil slurry mixing systems. The slurry preparation branch pipe is further divided into two lines, which deliver slurry to two slurry tanks respectively, and each tank is equipped with a valve and flow meter.

[0096] For a single cement-soil slurry mixing system, if 2 cubic meters are mixed each time, it takes at least 5 minutes each time. If 40 cubic meters are prepared for one ring, it would take at least 100 minutes to work. Although this can keep up with the tunnel boring machine for most projects, the working pressure on the equipment is too great. Therefore, this embodiment is equipped with two cement-soil slurry mixing systems. Both systems also have time for maintenance, and if one system fails, the other can still be used without affecting the tunnel boring machine.

[0097] Before preparing the synchronous grouting slurry, open the ball valve and valve to introduce the slurry into the slurry tank through the slurry inlet pipe. The slurry tank is equipped with a hydrometer and a stirring device, which are used to detect the specific gravity of the slurry and to stir the slurry to prevent bleeding, respectively.

[0098] Step 3: When preparing the main slurry, open the valve between the mud tank and the main slurry mixing tank, and control the mud volume by installing a flow meter at the valve.

[0099] Taking a single-unit cement-soil slurry mixing system as an example, 1m³ of slurry is added to the main slurry mixing tank. 3 Mud, with a specific gravity of 1.2 g / cm³. 3 Therefore, the mass of the mud is 1200 kg. Based on the main slurry mix ratio determined in step one, it is easy to calculate that 1.54 kg of retarder and 311.31 kg of cement need to be added to the main slurry.

[0100] After adding the mud, add the retarder to the main slurry mixing tank and stir at a speed of 1000 rpm or higher for at least 1 minute; then add the cement and stir at a speed of 1000 rpm or higher for at least 3 minutes.

[0101] Under this mix ratio, adding 137.79 kg of lubricating mud and 109.00 kg of water glass during subsequent grouting can theoretically yield a 1.29 m... 3 According to calculations, the grouting slurry accounts for 76% of the mass and 87% of the volume of the grouting slurry. The utilization rate of the slurry in the synchronous grouting slurry is very high, which can greatly reduce the amount of waste slurry to be disposed of.

[0102] The prepared main pulp is transported through pipeline to the main pulp storage tank (capacity 30m³). 3 *2) Storage. A flow meter and hydrometer are installed at the inlet of the main slurry storage tank to measure the volume and specific gravity of the main slurry entering the tank. A stirring device is installed in the main slurry storage tank, rotating at approximately 80 rpm, to continuously stir and prevent the main slurry from bleeding.

[0103] Step 4: The cement-soil grouting pipe uses a DN50 pipe with an inner diameter of 53mm, and a custom coaxial ring generator is used.

[0104] The main grout connector uses a steel pipe with an inner diameter of 48.6 mm, a thickness of 1 mm, and an outer diameter of 50.6 mm. The connecting pipe has an inner diameter of 53 mm, and the gap between it and the main grout connector is 1.2 mm to ensure smooth passage of lubricating slurry; its axial length l1 is 200 mm. A hole is drilled in the side wall of the connecting pipe for welding connection to the lubricating slurry connector, which uses a steel pipe with an inner diameter of 20 mm and a length l4 of 50 mm. The total length of the main grout connector is 550 mm, of which 50 mm extends beyond the top of the connecting pipe (l2), 200 mm is inside the coaxial annular cavity (same as l1), and 300 mm extends beyond the bottom of the connecting pipe and into the cement-soil grout connector (l3). The length of the cement-soil grout connector must not be less than the length l3 of the main grout connector extending into the cement-soil grout connector, which is 400 mm. Therefore, the ratio of the net cross-sectional area of ​​the main grout connector to the net cross-sectional area of ​​the connecting pipe in this project is 9.50, which, after conversion, corresponds to the volume ratio of the main grout to the lubricating slurry.

[0105] In this invention, the pipeline is filled with the main slurry and the lubricating mud, so it can basically maintain coaxiality. Even if there is a moment when the lubricating mud mixes with the adjacent main slurry during the transportation process, the viscosity is lower than that of the cement slurry, so the risk of pipe blockage is relatively reduced.

[0106] Before the initial construction or before clearing and re-grouting the grouting pipeline, the mud in the mud tank is pumped to the lubricating mud connector. The lubricating mud enters the cement-soil grout connector and the cement-soil grouting pipeline through the coaxial annular cavity to pre-lubricate the pipeline. After lubrication, the main grout in the main grout storage tank is pumped into the main grout connector and the cement-soil grout connector through the pipeline. When a stable coaxial grout is formed, it is then injected into the shield tail through the cement-soil grouting pipeline. The pre-lubricating mud and the unstable grout are discharged through the pipeline and do not enter the shield tail.

[0107] During grouting, the mixing ratio of cement-soil grout is ensured by controlling the injection volume of the main grout and the lubricating mud. The ratio of the main grout injection volume to the lubricating mud injection volume is equal to the ratio of the main grout volume to the lubricating mud volume. This project uses a two-component grout. The main grout, lubricating mud, and water glass are mixed in a mixer about 6m away from the shield tail and then injected into the shield tail gap.

[0108] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A construction method for preparing synchronous dual-liquid slurry using shield tunneling mud, characterized in that, include: S1. Through mix proportion tests, determine the mud index and mix proportion that simultaneously meet the requirements of shield tunneling and synchronous grouting, and prepare mud that simultaneously meets the requirements of both application conditions. The mix proportions include the mix proportions of cement slurry and water glass, the mix proportions of lubricating mud and main slurry in cement slurry, and the mix proportions of mud, retarder and cement in main slurry. S2. The prepared mud slurry is pumped into the tunnel through the slurry inlet pipe, and the mud slurry is introduced into the cement-soil slurry mixing station on the trolley behind the shield machine through the slurry preparation branch pipe. S3. Based on the mixing ratio of lubricating mud and main slurry, extract the corresponding mass of mud from the mud tank in the cement-soil slurry mixing plant as lubricating mud; based on the mixing ratio of main slurry, add mud, retarder and cement to the main slurry mixing tank in the cement-soil slurry mixing plant in sequence and mix evenly, and store the prepared main slurry in the main slurry storage tank. S4. During synchronous grouting, the coaxial ring generator is used to merge the main slurry and lubricating mud in the main slurry storage tank to form a double-layer coaxial slurry, so as to form a lubricating layer around the main slurry. Combined with the mixing ratio of cement-soil slurry and water glass, the double-layer coaxial slurry is pumped to the mixer to mix with water glass and then injected into the shield tail gap.

2. The construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 1, characterized in that, The process of determining the mud index and mix ratio that simultaneously meets the requirements of shield tunneling and synchronous grouting through mix ratio tests, and preparing mud that simultaneously meets the requirements of both application conditions, includes: S11. Based on the geological characteristics of the tunnel boring machine, determine the range of mud indexes for the tunneling mud, and combine the mud ratio test to determine the mud indexes and mix ratio required to prepare synchronous grouting slurry. S12. Based on the determined mud index and mix ratio, prepare mud at the mud station that simultaneously meets the requirements of shield tunneling and synchronous grouting.

3. The construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 1, characterized in that, The parameters of the lubricating mud are the same as those of the mud in the main slurry, and the sum of the mass of the mud in the main slurry and the mass of the lubricating mud is equal to the mass of the mud in the cement-soil slurry.

4. The construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 1, characterized in that, The slurry inlet pipe is equipped with several ball valves, and a slurry preparation branch pipe is connected to the ball valves near the cement-soil slurry mixing station. The slurry preparation branch pipe is equipped with a filter screen, valves and flow meters.

5. The construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 1, characterized in that, The slurry in the slurry inlet pipe is used to balance the working face, carry slag, or flush, while the slurry in the slurry preparation branch pipe is used to prepare cement-soil slurry for synchronous grouting.

6. The construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 1, characterized in that, The cement-slurry mixing plant includes a mud tank, a main slurry mixing tank, a retarder tank, a cement tank, and a main slurry storage tank.

7. A construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 1, characterized in that, The coaxial ring generator consists of a coaxial ring (1) and a cement-soil grout connector (2) that cooperates with it; The coaxial ring (1) includes a main slurry connector (11), and the bottom end of the main slurry connector (11) extends downward into the interior of the cement-soil slurry connector (2). A connecting pipe (12) is sleeved on the outside of the main slurry connector (11) to cooperate with it, and the bottom end of the connecting pipe (12) is connected to the top end of the cement-soil slurry connector (2). A coaxial annular cavity (13) is formed between the inner diameter of the connecting pipe (12) and the outer diameter of the main slurry connector (11). A lubricating mud slurry connector (14) is provided on one side of the connecting pipe (12).

8. A construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 7, characterized in that, The main slurry pipe (11), the connecting pipe (12) and the cement-soil slurry pipe (2) are coaxially arranged, and the top end of the main slurry pipe (11) extends above the connecting pipe (12) and is connected to the main slurry storage tank through a pipe.

9. A construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 7, characterized in that, The size of the coaxial annular cavity (13) is matched with the volume ratio of the main slurry to the lubricating mud in the cement slurry; The ratio of the net cross-sectional area of ​​the connecting pipe (12) to the net cross-sectional area of ​​the main slurry pipe (11) is equal to the volume ratio of the lubricating mud to the main slurry.

10. A construction method for preparing synchronous dual-liquid slurry using shield tunneling mud according to claim 7, characterized in that, Before the first construction or before emptying the grouting pipeline and re-grouting, the mud in the mud tank is pumped to the lubricating mud connector (14), so that the lubricating mud enters the cement-soil grout connector (2) and the cement-soil grouting pipeline through the coaxial annular cavity (13) to pre-lubricate the pipeline.

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