Grouting slurry and synchronous grouting method suitable for shield construction in water-rich sandy cobble stratum with large slope

Abstract

The application relates to a grouting slurry and a synchronous grouting method suitable for shield construction of a large-gradient section of a water-rich sandy cobble stratum and belongs to the technical field of shield construction. 3 , fly ash 500~650 kg / m 3 , sodium-based bentonite 70~90 kg / m 3 , sand 900~1100 kg / m 3 , polystyrene 1.5~2.5 kg / m 3 , silicon powder 2~3 kg / m 3 , hydroxypropyl methylcellulose 0.005~0.01 kg / m 3 , water 300~320 kg / m 3 , B liquid: water glass 25~40 L / m 3 , polyacrylamide solution 5~10 L / m 3 , modified polycarboxylate 0.5~1.5 kg / m 3 The slurry with specific components and proportions can effectively solve the anti-dispersion problem in a water-rich environment, and in combination with a specific grouting process, can effectively prevent the segment from floating and improve the tunnel forming quality.

Description

Technical Field

[0001] This application relates to the field of tunnel boring machine (TBM) construction technology, and in particular to grouting slurry and synchronous grouting method applicable to TBM construction in steep slope sections of water-rich sandy gravel strata. Background Technology

[0002] Shield tunneling, due to its high degree of mechanization and minimal disturbance to the surrounding strata, has become a key method for underground space construction such as urban subways and river-crossing tunnels. In shield tunnel construction, synchronous grouting to fill the annular gaps created during shield excavation is a crucial construction measure to ensure structural safety and control surface settlement and relative displacement of tunnel segments. Conventional synchronous grouting techniques and traditional grout formulations have been widely applied and validated in sections with relatively uniform soil and rock conditions and gentle slopes. However, when encountering water-rich sandy gravel strata with steep slopes, conventional synchronous grouting methods and traditional grout formulations face several technical challenges. Water-rich sandy gravel strata are characterized by coarse particle size distribution, high porosity, high permeability, and strong groundwater flow, leading to problems such as rapid grout loss, mud washing, difficulty in transmitting grouting pressure, and passive runoff. This reduces grouting efficiency and makes it difficult to form a continuous, uniform, and load-bearing grout coating. At the same time, the gravity driven by the steep slope causes the grout to flow asymmetrically in the pores, with the grout remaining at the shield tail in the uphill area and accumulating at the shield head in the downhill area. This makes it difficult to ensure uniform filling of the grout and cannot effectively reinforce the strata. It also increases the risk of segment floating, misalignment, uneven stress in the annulus, and local surface uplift or subsidence.

[0003] Synchronous grouting, a key method for filling the shield tail void and stabilizing the surrounding rock, involves injecting a grout with gelling and solidifying properties into the gap between the tunnel segments and the strata in real time. This forms a circumferential support to counteract ground stress release, control soil erosion, and reinforce the strata. Existing technologies generally use fly ash-bentonite inert grout or cement-based single-component grout, with grouting parameters relying on empirical values. In homogeneous strata, this generally meets construction requirements. However, when applied to tunnels in water-rich sandy and gravelly strata, traditional grout components lack anti-water-dispersion materials, making grout retention difficult and resulting in significant grout loss along the pores of the sand and gravel, failing to effectively seal seepage paths. Cement-based grouts have a delayed setting time, leading to excessive final setting time, high grout loss rates, and insufficient strength after grout formation, inducing excessive upward displacement of the tunnel segments. Meanwhile, existing grouting techniques are poorly adapted to steep slope conditions. Traditional grouting methods often employ a symmetrical grouting pattern, failing to consider the gravity effect and groundwater seepage in steep slope sections of water-rich sandy gravel strata. This fails to effectively suppress problems such as segment uplift and uneven grouting in steep sections. These issues severely affect the tunnel's forming quality and safety. Therefore, current shield tunneling in steep slopes in water-rich sandy gravel strata faces long-term risks such as segment misalignment and surface subsidence.

[0004] While Chinese patent CN111779494A proposes a grouting method for controlling segment uplift during shield tunneling, this method is not applicable to water-rich sandy gravel strata. Although it improves upon traditional grouting techniques, it only works in homogeneous strata and does not consider the influence of shield slope. Furthermore, its pressure compensation mechanism cannot cope with the uplift force caused by steep slopes. Water-rich sandy gravel strata are heterogeneous mixtures composed of sand, gravel, and a small amount of clay with significantly different particle sizes. These strata have high permeability and rapid groundwater flow. During steep-slope shield tunneling in water-rich sandy gravel strata, the unstable arrangement of the gravel skeleton easily leads to stress concentration. Fine particles are continuously lost under the influence of flowing water, making it difficult for traditional grout to form an effective seal, resulting in significant risks such as segment misalignment and surface subsidence. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of existing technologies, which cannot solve the problem of grout dispersion in water-rich environments and cannot adapt to the mechanical environmental changes brought about by steep slopes, severely restricting construction safety and quality. Therefore, this application proposes a grouting slurry and simultaneous grouting method suitable for shield tunneling in steep slopes of water-rich sandy gravel strata. This application uses a grouting slurry with specific components and proportions to effectively solve the problem of grout dispersion in water-rich environments. Furthermore, by combining the grouting slurry described in this application with a specific grouting process, it can effectively prevent the shield tunneling machine segments from floating during shield tunneling in steep slopes of water-rich sandy gravel strata, thereby improving tunnel forming quality and preventing disasters such as surface subsidence and rupture of adjacent pipelines.

[0006] Firstly, this application provides a technical solution for a grouting slurry suitable for shield tunneling in steep slope sections of water-rich sandy gravel strata, using the following method: the raw materials of the grouting slurry include liquid A and liquid B, with a grouting volume of 3.8 m³ per ring. 3 Based on the volume, the raw materials for liquid A include: 40~60 kg / m³ of slaked lime. 3 Specifically, for example, it could be 40 kg / m 3 45 kg / m 3 50 kg / m 3 55 kg / m 3 Or 60 kg / m 3 fly ash 500~650 kg / m³ 3 Specifically, for example, it could be 500 kg / m 3 550 kg / m 3 580 kg / m 3 625 kg / m 3 Or 650 kg / m 3 Sodium-based bentonite 70~90 kg / m³ 3Specifically, for example, it could be 70 kg / m 3 75 kg / m 3 80 kg / m 3 85 kg / m 3 Or 90 kg / m 3 Sand 900~1100 kg / m³ 3 Specifically, for example, it could be 900 kg / m 3 1000 kg / m 3 Or 1100 kg / m 3 Polystyrene 1.5~2.5 kg / m 3 Specifically, for example, it could be 1.5 kg / m³ 3 1.8 kg / m 3 2.0 kg / m 3 2.3 kg / m 3 Or 2.5 kg / m 3 Silicon powder 2~3 kg / m 3 Specifically, for example, it could be 2 kg / m 3 2.3 kg / m 3 2.7 kg / m 3 Or 3 kg / m 3 Hydroxypropyl methylcellulose 0.005~0.01 kg / m 3 Specifically, for example, it could be 0.005 kg / m 3 0.008 kg / m 3 Or 0.01kg / m 3 Water 300~320 kg / m 3 Specifically, for example, it could be 300 kg / m 3 310 kg / m 3 Or 320 kg / m 3 The raw materials for solution B include: 25-40 L / m³ of water glass. 3 Specifically, for example, it can be 25 L / m 3 26 L / m 3 30 L / m 3 or 40 L / m 3 5~10 L / m of polyacrylamide solution 3 Specifically, for example, it can be 5 L / m 3 8 L / m 3 Or 10 L / m 3 Modified polycarboxylate 0.5~1.5 kg / m 3 Specifically, for example, it could be 0.5 kg / m 3 0.9 kg / m3 1.3 kg / m 3 Or 1.5 kg / m 3 In this application, the grouting volume per ring is 3.8 m. 3 This refers to the total volume of grout injected into all grouting pipes in each ring of tunnel segments being 3.8 m³. 3 .

[0007] Through the above technical solution, liquid A serves as the base slurry. Slaked lime provides Ca(OH)2 activity, enhancing the water retention of the base slurry. Fly ash improves the workability of the slurry and reduces viscosity. Sodium-based bentonite improves the suspension stability of the slurry and controls the bleeding rate to ≤5%. Sand serves as aggregate to fill voids. Polystyrene adjusts the coefficient of thermal expansion and contraction of the slurry, enhancing crack resistance. Silica powder fills micropores and improves impermeability. Hydroxypropyl methylcellulose serves as an anti-dispersing agent, improving the slurry retention rate under dynamic water conditions. Water regulates the fluidity of the slurry. Liquid B serves as a coagulant accelerator. Water glass serves as the main coagulant accelerator, providing rapid gelation. Polyacrylamide solution enhances the shear resistance of the slurry and improves flow permeability. Modified polycarboxylate increases the early strength formation rate of the slurry.

[0008] With a grouting volume of 3.8 m per ring. 3 Based on the volume, in the A solution, when the amount of slaked lime is less than 40 kg / m³ 3 When the Ca(OH)2 content is insufficient, the water retention of the slurry decreases. When the amount of hydrated lime is greater than 60 kg / m³, the water retention of the slurry also decreases. 3 If the slurry viscosity is too high and its fluidity decreases, it will be difficult to pump. This is especially true when the fly ash content is less than 500 kg / m³. 3 When the amount of fly ash exceeds 650 kg / m³, the solidified structure becomes coarser, the porosity increases, and the strength is insufficient. 3 When the initial setting time of the grout is significantly prolonged and the early strength is insufficient, the amount of sodium-based bentonite used is less than 70 kg / m³. 3 When the amount of sodium-based bentonite used is greater than 90 kg / m³, the slurry bleeding rate increases significantly, and it is prone to segregation and stratification. 3 When the amount of sand used is less than 900 kg / m³, the diffusion range is significantly reduced, making it difficult to fill the entire annulus. 3 If the slurry density is insufficient, the skeleton structure is unstable, the bleeding rate increases, and the solidified body strength is insufficient, it can easily lead to segment floating and annular support failure. When the amount of sand used is greater than 1100 kg / m³, 3 When the viscosity of the grout increases significantly, pumping becomes difficult, diffusion capacity is insufficient, and the brittleness of the solidified body increases, easily causing uneven filling of the annulus and failing to meet the requirements of synchronous grouting construction in steep slope sections of water-rich sandy gravel strata. When the amount of polystyrene used is less than 1.5 kg / m³... 3When the amount of polystyrene used is greater than 2.5 kg / m³, the slurry's ability to resist buoyancy decreases. 3 If the amount of silica powder used is less than 2 kg / m³, the slurry strength will be too low to withstand external water pressure. 3 When the amount of hydroxypropyl methylcellulose exceeds 3 kg / m³, the solidified body becomes insufficiently dense and its porosity increases. 3 When the amount of hydroxypropyl methylcellulose is less than 0.005 kg / m³, the solidified body becomes more brittle and easily destroyed. 3 When the amount of hydroxypropyl methylcellulose exceeds 0.01 kg / m³, the slurry's resistance to erosion decreases, making it more susceptible to being carried away by groundwater. 3 When the grouting diffusion radius is reduced, it becomes difficult to fill the shield tail annulus. This is especially true when the water usage is less than 300 kg / m³. 3 When the water content exceeds 320 kg / m³, the slurry density becomes unstable and the overall molding quality decreases. 3 If the slurry is too thin and has excessive fluidity, it is prone to excessive diffusion and a decrease in strength.

[0009] With a grouting volume of 3.8 m per ring. 3 Based on the volume, in solution B, when the amount of water glass used is less than 25 L / m³ 3 When the initial setting time of the slurry is significantly prolonged, a rapid support layer cannot be formed. This is especially true when the amount of water glass used exceeds 40 L / m³. 3 When the slurry diffusion radius is significantly reduced, the filling becomes uneven, and the strength decreases, especially when the amount of polyacrylamide solution used is less than 5 L / m³. 3 When the viscosity of the slurry is too low and its fluidity is too high, it is difficult to retain in the pores. When the amount of the polyacrylamide solution used is greater than 10 L / m 3 If the slurry becomes too viscous, it cannot form a uniform support layer. This is especially true when the amount of the modified polycarboxylate is less than 0.5 kg / m³. 3 When the amount of the modified polycarboxylate exceeds 1.5 kg / m³, the gel bonding ability is insufficient, the erosion resistance is weak, and the early strength is low. 3 If the reaction is too fast, the viscosity will be too high, the diffusion will be insufficient, the solidified body will become brittle, and the filling will be uneven.

[0010] In a specific embodiment of the grouting slurry, the preparation method of liquid A is as follows: sand, slaked lime, sodium bentonite and polystyrene are mixed evenly in a mixer at a stirring speed of ≥60 r / min (uneven mixing will lead to uneven dispersion of aggregate and cementitious material, resulting in insufficient local strength). Then, fly ash and silica powder are added to the mixer and the mixture is stirred evenly. Next, water is added to the mixer in three batches (to avoid adding water all at once, which may cause slurry segregation). Water is added while stirring each time until the materials in the mixer are evenly mixed. Finally, hydroxypropyl methylcellulose is added to the mixer and stirred evenly (adding hydroxypropyl methylcellulose in advance will cause it to degrade due to prolonged stirring and lose its anti-water dispersion function). The preparation and storage environment temperature of the A liquid needs to be controlled between 5 and 35 ℃ (when the temperature is <5 ℃, the cement hydration reaction slows down, and the initial setting time will exceed the standard of 4 to 6 hours; when the temperature is >35 ℃, the slurry water evaporates too quickly, the consistency will exceed the range of 8 to 12 cm, and it is easy to set prematurely); the relative humidity needs to be ≥60% (too low humidity will cause the slurry surface to lose water and form a crust, and the internal bleeding rate will increase, affecting the integrity of the solidified body; if the humidity is <40%, the stone rate may drop to below 95%).

[0011] In a specific embodiment of the grouting slurry, the preparation method of liquid B is as follows: water glass and polyacrylamide solution are mixed evenly, then modified polycarboxylate is slowly added to the mixture and stirred evenly, and finally water is added to adjust the total volume of liquid B to 50~60 L / m³. 3 Use after standing and defoaming.

[0012] Optionally, the preparation method of the modified polycarboxylate includes the following steps:

[0013] (1) Polyethylene glycol monomethyl ether acrylate and water are mixed at 40~50 °C, and then the mixed system, acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid are mixed to form a monomer mixture;

[0014] (2) At 65~70 °C, an initiator solution is added dropwise to the monomer mixture to carry out a polymerization reaction. When the viscosity of the polymerization product is 800~1200 mPa·s, mercaptoacetic acid is added to the polymerization product, and the temperature is raised to 75~80 °C to carry out the reaction. After the reaction is completed, the temperature is lowered to 40~50 °C, and the pH value is adjusted to 6.0~7.0.

[0015] (3) The system after pH adjustment in step (2) is mixed with the silane coupling agent and reacted, wherein the content of the silane coupling agent is 1~2% based on the total mass of the system after pH adjustment as 100%, specifically, the content of the silane coupling agent can be 1%, 1.2%, 1.5%, 1.8% or 2%;

[0016] (4) Filter the reaction product in step (3) and spray dry the filtrate to obtain modified polycarboxylate.

[0017] Using the above technical solution, the modified polycarboxylate prepared by this method can be used as one of the raw materials of liquid B. With the synergistic effect of liquid A and liquid B, the grout prepared by mixing liquid A and liquid B can have excellent resistance to dynamic water erosion when tunneling is carried out in water-rich sandy gravel strata with steep slopes. It can also quickly achieve the required early strength, avoid the phenomenon of segment floating during tunneling, and significantly improve the safety and quality of tunneling.

[0018] When the viscosity of the polymerization product is less than 800 mPa·s, adding mercaptoacetic acid to the polymerization product will result in insufficient polymerization conversion, low molecular weight, and reduced dispersion, bonding, and early strength promotion effects of the modified polycarboxylate in the slurry. When the viscosity of the polymerization product is greater than 1200 mPa·s, adding mercaptoacetic acid to the polymerization product will result in poor solution operability, difficulty in subsequent dosing and dissolution, and excessive viscosity, pumping, and mixing problems in solution B. In step (3), when the content of the silane coupling agent is less than 1%, the coupling effect is weakened, and the interaction between the modified polycarboxylate and the inorganic is insufficient. When the content of the silane coupling agent is greater than 2%, it will cause excessive crosslinking or silane polymerization byproducts, increase viscosity, and lead to filtration difficulties.

[0019] In the specific preparation process of the modified polycarboxylate, in step (4), the reaction product in step (3) is filtered with an ultrafiltration membrane with a molecular weight cutoff of 5000 to remove unreacted monomers; the conditions for spray drying are: inlet air temperature of 180~200 ℃ and outlet air temperature of 80~90 ℃.

[0020] Optionally, the ratio of polyethylene glycol monomethyl ether acrylate, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, initiator solution and mercaptoacetic acid is 1 g: 10~12 mL: 3~6 g: 10~25 mL: 1~10 mL.

[0021] Through the above technical solutions and continuous adjustment and testing, the raw materials for the preparation of modified polycarboxylate can be limited to a certain range, which can further improve the grouting slurry's resistance to dynamic water erosion. The initial setting time of the grouting slurry can be adjusted to 2-6 hours to avoid insufficient slurry strength due to excessive final setting time, which could induce excessive floating displacement of the pipe segments.

[0022] Optionally, the fly ash is Class II fly ash, the fineness modulus of the sand is 0.5~1.5, the average particle size of the polystyrene is ≤50 μm, the SiO2 content in the silicon powder is ≥90%, and the viscosity of the hydroxypropyl methylcellulose is 20000~40000 mPa·s.

[0023] Through extensive experimental research, the inventors of this application have discovered that by limiting the relevant parameters of fly ash, sand, polystyrene, silica fume, and hydroxypropyl methylcellulose to a certain range, liquid A can meet the following performance requirements: initial setting time: 4~6 h; solidified body strength: not less than 0.2 MPa at 1 day and not less than 2.5 MPa at 28 days; slurry stone formation rate: >95%, i.e., consolidation shrinkage rate <5%; slurry consistency: 8~12 cm.

[0024] Optionally, the polyacrylamide solution is a mixed solution of anionic polyacrylamide and water, wherein the molecular weight of the anionic polyacrylamide is 8 million to 12 million.

[0025] Through the above technical solution, the use of anionic polyacrylamide can enhance the shear resistance of the slurry and improve its flow permeability. At the same time, the molecular weight of the anionic polyacrylamide is limited to 8 million to 12 million, which can make the B liquid meet the following performance requirements: mass concentration reaches 2‰, the initial setting time after mixing with the A liquid can be adjusted to 2 to 6 h, the slurry retention rate is >90% when the dynamic water flow rate is 1.2 m / s, and the compressive strength is ≥0.5 MPa after 1 h.

[0026] Secondly, the synchronous grouting method for shield tunneling in steep slope sections of water-rich sandy gravel strata provided in this application adopts the following technical solution: The method includes the following steps:

[0027] S1. During the construction process, real-time construction data is acquired, including earth pressure, slope, groundwater flow velocity, segment rolling angle, and grouting pressure.

[0028] S2. Construct a dynamic compensation model for grouting volume using the construction data. The dynamic compensation model for grouting volume is shown in equation (1):

[0029] Q d = Q b ×[1+ K p ×(θ-θ0)+ K v ×(v-v0)] Equation (1)

[0030] In equation (1), Q d This represents the adjusted grouting volume.Q b This represents the amount of grout injected into the foundation before adjustment. K p Represents the slope compensation coefficient. K p The value is 0.015 / ‰. K v Represents the velocity compensation coefficient. K v The value is 0.1, θ represents the real-time slope value, θ0 represents the initial slope value, v represents the real-time groundwater flow velocity, and v0 represents the initial groundwater flow velocity.

[0031] S3. Based on the dynamic compensation model for grouting volume and the real-time slope value and real-time groundwater flow velocity of the section to be grouted, the grouting volume of the section to be grouted during construction is dynamically adjusted. During construction, the grouting slurry used in the section to be grouted is the grouting slurry described above, suitable for shield tunneling in steep slopes of water-rich sandy gravel strata. In this application, the terrain in the initial stage of shield tunneling is horizontal; therefore, the foundation grouting volume before adjustment refers to the grouting volume under general conditions, which is an empirical value derived from the construction plan. For example, the foundation grouting volume before adjustment... Q b The grouting volume per ring can be 3.8m. 3 The initial slope value can be 0. Before the tunnel boring machine (TBM) starts excavating (i.e. when the TBM is on a horizontal surface), data will be collected. The initial groundwater flow velocity obtained at this time is the initial groundwater flow velocity.

[0032] By employing the aforementioned technical solution, when conducting shield tunneling in steep slope sections of water-rich sandy gravel strata, the grouting volume can be dynamically adjusted based on real-time acquired construction parameters and a dynamic compensation model for grouting volume. This can essentially meet the construction requirements of steep slope sections of water-rich sandy gravel strata, preventing secondary disasters such as ground subsidence and rupture of adjacent pipelines. In this application, the slope value of the steep slope section of the water-rich sandy gravel strata is ≥30‰, and the water content is 20~40%.

[0033] In a specific implementation of the synchronous grouting method, six sets of earth pressure sensors (two sets each at the front, middle, and rear of the tunnel boring machine) are installed on the shield machine to collect earth pressure at a sampling frequency of 10 Hz. Simultaneously, the roll angle and pitch angle (i.e., slope) of the tunnel segments are monitored in real time. Two pressure sensors with a range of 0-1 MPa and an accuracy of 0.01 MPa are installed in the grouting pipeline to collect grouting pressure data. Groundwater flow velocity is measured using a rotary velocimeter. During operation, by dynamically adjusting the grouting volume in the grouting section, the earth pressure and roll angle of the tunnel segments can be maintained within the specified requirements; that is, the earth pressure is maintained within 90-110% of the theoretical earth pressure, and the roll angle is maintained within the threshold range of ±0.5° to ±1.0°.

[0034] In a specific implementation of the synchronous grouting method, the method for constructing a dynamic compensation model for grouting volume using the construction data is as follows: First, numerical simulation is performed. Specifically, based on real-time data collected during construction, such as earth pressure, slope, rolling angle, and grouting pressure, a shield tunneling model for water-rich sandy gravel strata is constructed using FLAC3D. This simulates the grout diffusion range, loss rate, and segment displacement under multiple different working conditions. The simulation data is then imported into MATLAB software, and a stepwise regression method is used to construct the quantitative relationship with the input variables. Variables with weak correlations are eliminated, ultimately yielding the dynamic compensation model. K ad =1+ K p ×(θ-θ0)+ K v ×(v-v0) Equation (2), in Equation (2), K ad Represents the dynamic adjustment coefficient;

[0035] Then, theoretical analysis was conducted. The specific process of theoretical analysis was as follows: (1) The mechanical balance theory of segment anti-buoyancy: When going uphill on a steep slope, the segment is affected by the upward component of the shield thrust (F_up) and the buoyancy of the grout (F_buoy). It is necessary to adjust the grouting volume to ensure that the supporting force after the grout solidifies is ≥ F_up + F_buoy. Based on this theory, the numerical analysis was verified. K p The rationale is that when θ = 40‰, F_up increases, requiring an increase in the grouting volume to enhance the offsetting ability of F_buoy, which aligns with numerical analysis. K p =0.015 / ‰, which is consistent with the adjustment trend, and the calculated grouting volume adjustment is less than 5% of the numerical simulation result; (2) Darcy's law is used to analyze the grout diffusion loss: in water-rich sandy gravel strata, the grout diffusion radius R Satisfying equation (3):

[0036] Equation (3)

[0037] In equation (3), R Where is the slurry diffusion radius, Pg For grouting pressure, k The formation permeability coefficient, t The effective diffusion time of the slurry. u For slurry viscosity, n Formation porosity;

[0038] The grouting volume must cover the shield tail gap volume and the grout loss volume (V_loss=πR²×L×n, where L is the length of the grouting section). Based on this theory, verification... Kv The rationale is that as v increases (due to the increase in P_avg leading to an increase in the hydraulic gradient, where P_avg refers to the soil pressure), V_loss (the volume of grout loss) increases, requiring an increase in the grouting volume, which aligns with the numerical analysis. K v The adjustment logic of =0.1 / (m / s) is consistent, and the calculated value of V_loss matches the slurry loss rate in the numerical simulation by more than 90%.

[0039] Optionally, when the section to be grouted is an uphill section, the grouting holes in the uphill section include top grouting holes, bottom grouting holes, and side grouting holes. Taking the total grouting volume of the uphill section as 100%, the grouting volume of the top grouting holes is 60-70%, for example, 60%, 65%, or 70%; the grouting volume of the bottom grouting holes is 20-30%, for example, 20%, 25%, or 30%; and the grouting volume of the side grouting holes is 5-15%, for example, 5%, 10%, or 15%. In this application, the uphill section is a section with a certain slope above the horizontal plane. The positions of the top grouting holes, bottom grouting holes, and side grouting holes are as follows... Figure 1 As shown.

[0040] With the above technical solution, taking the total grouting volume of the upslope section as 100%, when the grouting volume of the top grouting hole is less than 60% and the grouting volume of the bottom grouting hole is greater than 30%, the grout distribution in the annulus will be eccentric downwards, weakening the covering and locking effect on the top of the segment, resulting in problems such as increased segment floating and rolling, uneven grouting filling, excessive pressure at the bottom, and grout loss. When the grouting volume of the top grouting hole is greater than 70% and the grouting volume of the bottom grouting hole is less than 20%, the top grout will be excessive and form an excessively thick or prematurely solidified rigid layer in the upper part of the annulus, thereby hindering the downward diffusion of the grout and causing insufficient filling at the bottom of the annulus, resulting in problems such as discontinuous filling, uneven stress, and tensile stress on the joints.

[0041] Optionally, when the section to be grouted is a downhill section, the grouting holes in the downhill section include top grouting holes, bottom grouting holes, and side grouting holes. With the total grouting volume of the downhill section as 100%, the grouting volume of the top grouting holes is 20-40%, for example, 20%, 30%, or 40%; the grouting volume of the bottom grouting holes is 40-60%, for example, 40%, 50%, or 60%; and the grouting volume of the side grouting holes is 10-30%, for example, 10%, 20%, or 30%. In this application, the downhill section is a section with a certain slope below the horizontal plane.

[0042] With the above technical solution, taking the total grouting volume of the downslope section as 100%, when the grouting volume of the top grouting hole is less than 20% and the grouting volume of the bottom grouting hole is greater than 60%, the grout will concentrate downwards and be lost in the far field, forming an insufficiently filled cavity at the top. This is accompanied by uneven annular pressure, increased pore water pressure at the bottom, and increased formation disturbance, which leads to problems such as discontinuous annular filling, local settlement or misalignment of tunnel segments, damage to the shield tail seal, and waste of grouting material. When the grouting volume of the top grouting hole is greater than 40% and the grouting volume of the bottom grouting hole is less than 40%, the excessive grout at the top will hinder the downward penetration of the grout and prematurely form a local thick or prematurely set layer, resulting in insufficient bottom filling, discontinuous annular bearing capacity, and increased risk of tunnel segment settlement and misalignment.

[0043] Alternatively, when the section to be grouted is an uphill section, the grout used in the top grouting hole is a mixture of liquid A and liquid B with a mass ratio of 3 to 5:1, the grout used in the bottom grouting hole is a mixture of liquid A and liquid B with a mass ratio of 2 to 4:1, and the grout used in the side grouting hole is a mixture of liquid A and liquid B with a mass ratio of 1 to 3:1.

[0044] Alternatively, when the section to be grouted is a downhill section, the grout used in the top grouting hole is a mixture of liquid A and liquid B with a mass ratio of 4 to 6:1, the grout used in the bottom grouting hole is a mixture of liquid A and liquid B with a mass ratio of 2 to 4:1, and the grout used in the side grouting hole is a mixture of liquid A and liquid B with a mass ratio of 1 to 3:1.

[0045] By employing the aforementioned technical solutions, when conducting shield tunneling in steep slope sections of water-rich sandy gravel strata, in the upslope section, a specific mass ratio of a mixture of liquid A and liquid B is used as the grouting slurry for the top, bottom, and side grouting holes. This effectively inhibits segment uplift in the upslope section, reduces the rate of misalignment, improves grout retention and material utilization, and enhances surface settlement control. In the downslope section, using a specific mass ratio of a mixture of liquid A and liquid B as the grouting slurry for the top, bottom, and side grouting holes allows the grout to achieve optimal retention and consolidation under the combined effects of gravity and seepage, prevents premature hardening at the top from hindering grouting in the lower section, and counteracts the tendency of segments to slide down and settle in the downslope section.

[0046] When arranging the grouting pipeline, the pipeline for liquid A uses DN50 high-pressure steel wire braided hose with a pressure resistance of 1.2MPa; the pipeline for liquid B uses DN40 stainless steel pipe, equipped with an electric heating system to control the pipeline temperature within the range of 20±5℃, and the pipeline joints adopt a quick-locking structure with a sealing pressure of 1.5MPa. In this application, both the electric heating system and the quick-locking structure are conventional choices in the shield tunneling machine field. The electric heating system is a system function of heating the grouting pipe in the shield tunneling machine grouting device. The temperature can be adjusted on a large screen to ensure that the grout is in the optimal grouting condition. The quick-locking structure is a system function of the shield tunneling grouting system. After the grouting volume is set on the system, the pipeline will automatically close and grouting will stop once the specified grouting volume is reached. During grouting operation, grout circulation should be started 30 minutes before the start of tunneling, the grouting speed should be controlled at 25±5 L / min, and the pressure should be stabilized for 2 minutes after each ring of grouting is completed.

[0047] In the specific mixing process of liquid A and liquid B, a three-stage spiral static mixer with a mixing unit length of 50 cm is used, and the mixing time is controlled within the range of 3 to 5 minutes. At the same time, a turbulence elimination section with a length of 30 cm is set at the outlet. Both the three-stage spiral static mixer and the turbulence elimination section are conventional technologies in this field. The three-stage spiral static mixer is a slurry mixing device matched with the tunnel boring machine. The function of the turbulence elimination section is to ensure that the injected slurry can achieve stable pressure and enhance the accuracy of slurry injection.

[0048] Optionally, when the section to be grouted is an uphill section, the grouting pressure of the top grouting hole is 0.4~0.5 MPa, the grouting pressure of the bottom grouting hole is ≤0.2 MPa, and the grouting pressure of the side grouting hole is 0.3~0.35 MPa.

[0049] With the above technical solution, when the grouting section is an uphill section and the grouting pressure of the top grouting hole is less than 0.4 MPa, the grout will have difficulty overcoming the water pressure in the annulus at the top of the uphill section and the pore resistance of the sand and gravel layer. This will result in insufficient grout rising at the top, increased risk of top voids and segment floating. When the grouting pressure of the top grouting hole is greater than 0.5 MPa, it will easily cause the top grout to penetrate into the far field or erode and crack, resulting in excessive loss and potentially causing ground disturbance or local uplift. When the grouting pressure of the bottom grouting hole is greater than 0.2 MPa, the bottom grout will flow down and flow away along the slope or through the pores of loose sand and gravel, failing to form an effective load-bearing filling layer under the segments, thus leading to insufficient bottom support and the risk of segment subsidence. When the grouting pressure of the side grouting hole is less than 0.3 MPa, the diffusion range of the grout in the side is insufficient, which cannot effectively block the seepage channel in the side and easily causes the grout to leak along the side and become discontinuous in the annulus. When the grouting pressure of the side grouting hole is greater than 0.35 MPa, the grout may break through the weak interlayer or loose particles in the side, causing local sand and soil disturbance and causing the grout to be lost over a long distance.

[0050] Optionally, when the section to be grouted is a downhill section, the grouting pressure of the top grouting hole is 0.25~0.3 MPa, the grouting pressure of the bottom grouting hole is 0.35~0.4 MPa, and the grouting pressure of the side grouting hole is 0.3~0.35 MPa.

[0051] Through the above technical solution, when the section to be grouted is a downhill section, if the grouting pressure of the top grouting hole is less than 0.25 MPa, the top grout cannot overcome the water pressure in the annulus above the downhill section, resulting in insufficient top filling, which easily leads to upper voids and segment instability. If the grouting pressure of the top grouting hole is greater than 0.3 MPa, the grout is prone to seep downhill from the top or scour far-field pores, causing far-field loss, expansion of top voids, and local stratum disturbance. If the grouting pressure of the bottom grouting hole is less than 0.35 MPa, the grout is difficult to form a sufficiently thick load-bearing skeleton at the bottom, leading to insufficient bottom support and an increased risk of segment slippage or subsidence. If the grouting pressure of the bottom grouting hole is greater than 0.4 MPa, it may cause the grout to be forcibly squeezed out along the slope, scour sand and gravel aggregates, and generate far-field leakage, thereby causing unevenness or even destruction of the bottom load-bearing layer. When the grouting pressure of the side grouting hole is less than 0.3 MPa, the grout is difficult to diffuse to the side to form a sealing zone, and cannot effectively block the seepage channels in the sand and gravel layer. The grout loss in the side is serious. When the grouting pressure of the side grouting hole is greater than 0.35 MPa, it is easy to erode the side sand layer, cause local displacement or loosening, and cause the grout to spread unexpectedly along the side or downhill direction.

[0052] In a preferred embodiment of the synchronous grouting method, secondary grouting is performed on the section to be grouted. The grouting is performed 2-4 hours after the tunnel segment exits the shield tail. The grouting material is a two-component grout of ultrafine cement and water glass, with a water-cement ratio of 0.8:1 and a water glass content of 15%. The grouting pressure is 0.6-0.8 MPa, using a segmented pressurization method with a pressure difference of 0.2 MPa per stage. Using the secondary grouting method described in this application, residual voids that may have formed during the initial synchronous grouting can be effectively filled, significantly improving the integrity and density of the annular consolidation, further enhancing the bearing capacity around the tunnel segment, effectively reducing the risk of uneven settlement in the later stages, and gradually filling the voids in the near and far fields through segmented pressurization, thereby comprehensively ensuring the long-term stability and seepage prevention performance of the tunnel structure in steep, water-rich sandy and gravelly strata.

[0053] In summary, this application includes at least one of the following beneficial technical effects:

[0054] (1) The grouting slurry described in this application contains a specific component and a specific proportion of component A, whose construction performance is as follows: initial setting time: 4~6 h, solidified body strength: not less than 0.2 MPa at 1 day, not less than 2.5 MPa at 28 days, grout stone rate: >95%, i.e., consolidation shrinkage rate <5%, grout consistency: 8~12 cm. The grouting slurry contains a specific component and a specific proportion of component B, whose construction performance is as follows: concentration reaches 2‰, initial setting time can be adjusted to 2~6 h after mixing with component A, grout retention rate >90% at a dynamic water flow rate of 1.2 m / s, and compressive strength ≥0.5 at 1 h. MPa, the synergistic effect of liquid A and liquid B can make the grout prepared by mixing liquid A and liquid B have excellent resistance to dynamic water erosion when shield tunneling is carried out in water-rich sandy gravel strata with large slopes, and can quickly form the required early strength, avoiding the phenomenon of segment floating during shield tunneling, and significantly improving the safety and quality of shield tunneling.

[0055] (2) When conducting shield tunneling in water-rich sandy gravel strata with steep slopes, this application combines the grouting slurry with the dynamic compensation model for grouting volume, and dynamically adjusts the grouting volume according to the real-time construction situation in water-rich sandy gravel strata with steep slopes, thereby effectively preventing shield tunnel segments from floating and misaligning, and preventing disasters such as surface subsidence, thereby improving the quality of tunnel forming;

[0056] (3) In the preferred case, based on the actual situation of shield tunneling in the steep slope section of the water-rich sandy gravel stratum, dynamic grouting is carried out in the upslope section and downslope section, and the grouting slurry and grouting volume of the upslope section and downslope section are limited respectively. This can accurately control the grouting situation in different construction processes, reduce the floating amount of the tunnel segment by about 60%, reduce the occurrence rate of tunnel segment misalignment by about 80%, reduce the surface settlement rate by about 65%, and control the total settlement within 10 mm. Attached Figure Description

[0057] Figure 1 This is a schematic diagram showing the locations of the top grouting hole, bottom grouting hole, and side grouting hole in the tunnel segment in this application. Detailed Implementation

[0058] The following is in conjunction with the appendix Figure 1 The present application will be further described in detail with reference to specific embodiments.

[0059] The following examples further illustrate the grouting slurry and synchronous grouting method applicable to shield tunneling in steep slope sections of water-rich sandy gravel strata, as described in this application. These examples are implemented based on the technical solution of this application, providing detailed implementation methods and specific operating procedures; however, the scope of protection of this application is not limited to the following examples.

[0060] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0061] Fly ash: Grade II fly ash, purchased from Chengdu Yaoxin New Building Materials Co., Ltd.;

[0062] Sodium-based bentonite: Purchased from Hexinrunda Bentonite Mining Co., Ltd.;

[0063] Sand: Purchased from Sichuan Lanfeng Cement Co., Ltd., with a fineness modulus of 0.5~1.5;

[0064] Polystyrene: Purchased from Ruige Biotechnology, product number PS01000, average particle size 50 μm;

[0065] Silicon powder: Jiangsu Lianrui New Materials Co., Ltd., SiO2 content is 98%;

[0066] Hydroxypropyl methylcellulose: Purchased from Jinan Yuanlian Chemical Co., Ltd., viscosity 20000 mPa·s;

[0067] Water glass: Purchased from Chengdu Huayao Chemical Co., Ltd.;

[0068] Polyacrylamide: Anionic polyacrylamide, purchased from Henan Shunzhibang Environmental Protection Technology Co., Ltd., product number: SZB-0051, molecular weight: 12 million;

[0069] Polyethylene glycol monomethyl ether acrylate: Purchased from TCI (Shanghai) Chemical Industry Development Co., Ltd., product number P2698;

[0070] Silane coupling agent: KH-570, purchased from Guangzhou Yuanda New Materials Co., Ltd.;

[0071] Ultrafiltration membrane: molecular weight cutoff of 5000, purchased from Maiborui Biomembrane Technology Co., Ltd.

[0072] Test case

[0073] Initial setting time: measured using a Vicat apparatus;

[0074] Stone formation rate: Measured using standard molds, oven, balance, drying oven, and sieves. First, record the fresh sample mass M0. Pour the slurry into the mold and cure at room temperature for 28 days. After curing, remove the mold, clean the surface, and dry it. Record the dried mass M. d Calculate the stone rate = (M) d / M0)×100%;

[0075] Solidified body strength and 1-hour compressive strength: measured using a standard compressive strength testing machine;

[0076] Slurry consistency: Place the slump cone on a flat plate, fill it in three layers at a time, compact each layer 10 times with a tamping rod, scrape the upper surface, lift the slump cone vertically, and measure the maximum expansion diameter or vertical sinking height after the slurry spreads out. Take the average of the three measurements as the consistency result.

[0077] Slurry retention rate: Take a certain volume of slurry, dry it to obtain slurry mass M1, inject an equal volume of slurry into a straight water tank, and simultaneously turn on the water flow at a constant velocity of 1.2 m / s. Collect the outflowing slurry at the outlet of the straight water tank for a certain period of time, dry it to obtain mass M2, and calculate the slurry retention rate = (M2 / M1) × 100%;

[0078] Segment uplift: Measured using a total station;

[0079] Segment misalignment rate: Within the construction section, record whether misalignment occurs in each ring of segments (the tunnel is circular, and the segments form a ring to constitute the tunnel, so the number of rings is used in the project).

[0080] Surface subsidence rate and total surface subsidence: Single-point displacement gauges were used for monitoring. The total surface subsidence was the total surface subsidence during the monitoring period (30 days). Surface subsidence rate = daily subsidence value / number of observations. The daily subsidence value refers to the subsidence value with the largest daily change (the most unfavorable value during the period). The number of observations is the number of measurements taken each day.

[0081] Preparation Examples 1-3 illustrate the preparation of modified polycarboxylate salts.

[0082] Preparation Example 1

[0083] Preparation of modified polycarboxylate:

[0084] (1) Add 1 g of polyethylene glycol monomethyl ether acrylate to the reactor and add 20 mL of deionized water. While stirring, raise the temperature to 45°C at a stirring rate of 350 r / min. After raising the temperature to 45°C, continue stirring for 30 min until the polyethylene glycol monomethyl ether acrylate is completely dissolved. Add 12 mL of acrylic acid and 5 g of 2-acrylamide-2-methylpropanesulfonic acid to the dissolved system in sequence, and continue stirring for 15 min to form a monomer mixture.

[0085] (2) The monomer mixture was heated to 70°C, and 25 mL of 3% ammonium persulfate solution (initiator solution) was added dropwise to the monomer mixture at a constant rate for 2 h. After the ammonium persulfate solution was added, the mixture was kept warm and stirred for 2.5 h. The viscosity of the polymerization product was found to be 1000 mPa·s. 8 mL of mercaptoacetic acid was added to the polymerization product, the temperature was raised to 80°C and reacted for 1 h. Then the temperature was lowered to 50°C and the pH value was adjusted to 6.5 with 30% sodium hydroxide solution.

[0086] (3) Mix 100 g of the pH-adjusted system from step (2) with 1.5 g of silane coupling agent KH-570 (the content of the silane coupling agent is 1.5% based on the total mass of the pH-adjusted system as 100%) and stir for 1 h.

[0087] (4) The reaction product in step (3) is filtered with an ultrafiltration membrane with a molecular weight cutoff of 5000, and the filtrate is spray-dried (inlet air temperature 180℃, outlet air temperature 90℃) to obtain a white powdery modified polycarboxylate.

[0088] Preparation Example 2

[0089] The preparation method was carried out as in Example 1, except that the content of the silane coupling agent was 5% based on the total mass of the system after pH adjustment as 100%.

[0090] Preparation Example 3

[0091] Preparation of modified polycarboxylate:

[0092] (1) Add 1.5 g of polyethylene glycol monomethyl ether acrylate to the reactor and add 25 mL of deionized water. While stirring, raise the temperature to 45°C at a stirring rate of 350 r / min. Continue stirring for 30 min after raising the temperature to 45°C until the polyethylene glycol monomethyl ether acrylate is completely dissolved. Add 15 mL of acrylic acid and 6 g of 2-acrylamide-2-methylpropanesulfonic acid to the dissolved system in sequence and continue stirring for 15 min to form a monomer mixture.

[0093] (2) The monomer mixture was heated to 70°C, and 20 mL of ammonium persulfate solution (initiator solution) with a mass fraction of 2% was added dropwise to the monomer mixture at a uniform rate for 2 h. After the ammonium persulfate solution was added, the mixture was kept warm and stirred for 2.5 h. The viscosity of the polymerization product was found to be 1500 mPa·s. 4 mL of mercaptoacetic acid was added to the polymerization product, the temperature was raised to 80°C and reacted for 1 h. Then the temperature was lowered to 50°C and the pH value was adjusted to 6.5 with sodium hydroxide solution with a mass fraction of 30%.

[0094] (3) Mix 150 g of the pH-adjusted system from step (2) with 2.25 g of silane coupling agent KH-570 (based on the total mass of the pH-adjusted system being 100%, the content of the silane coupling agent is 1.5%) and stir for 1 h.

[0095] (4) The reaction product in step (3) is filtered with an ultrafiltration membrane with a molecular weight cutoff of 5000, and the filtrate is spray-dried (inlet air temperature 180℃, outlet air temperature 90℃) to obtain a white powdery modified polycarboxylate.

[0096] Examples 1-4 and Comparative Examples 1-4 describe the raw materials and preparation of grouting fluids suitable for shield tunneling construction on steep slopes in water-rich sandy and gravelly strata.

[0097] Example 1

[0098] A grouting slurry suitable for shield tunneling in steep slopes with water-rich sandy and gravelly strata, the grouting slurry comprising liquid A and liquid B, with a grouting volume of 3.8 m per ring. 3 Based on the volume, the raw materials for liquid A include: 55 kg / m³ of slaked lime. 3 fly ash 625 kg / m³ 3 Sodium-based bentonite 80 kg / m 3 1100 kg / m³ of sand 3 Polystyrene 2.3 kg / m3 Silicon powder 2.7kg / m 3 Hydroxypropyl methylcellulose 0.01 kg / m 3 310 kg / m³ of water 3 The raw materials for solution B include: 40 L / m³ of water glass. 3 8 L / m³ of polyacrylamide solution (a mixed solution of polyacrylamide and water, concentration 8%) 3 The modified polycarboxylate obtained in Preparation Example 1 was 1.3 kg / m 3 56 L / m 3 .

[0099] The preparation process of liquid A is as follows: Liquid A is prepared according to the raw materials and dosages described in Example 1. First, sand, slaked lime, sodium bentonite, and polystyrene are added sequentially to a mixer and dry-mixed for 2 minutes. Then, fly ash and silica powder are added to the mixer and stirred for another 1 minute. Next, water is added to the mixer in three batches, stirring for 3 minutes each time. Finally, hydroxypropyl methylcellulose is added to the mixer and stirred for 5 minutes. All raw materials are mixed evenly to obtain liquid A. The stirring speed of the mixer is 60 r / min, the temperature during the preparation process is 25℃, and the relative humidity is 85%. Liquid A is tested for initial setting time, stone formation rate, solidified body strength, and slurry consistency. The test results are as follows: the initial setting time of liquid A is 4.5 h; the solidified body strength is 0.27 MPa at 1 day and 2.9 MPa at 28 days; the stone formation rate is 95%; and the slurry consistency is 9 cm.

[0100] The preparation process of liquid B is as follows: Liquid B is prepared according to the raw materials and dosages described in Example 1. First, water glass and polyacrylamide solution are mixed and stirred for 5 minutes until homogeneous. Then, the modified polycarboxylate obtained in Preparation Example 1 is slowly added to the homogeneous mixture, and stirring is continued for 10 minutes to ensure complete dissolution of the modified polycarboxylate. Finally, water is added and allowed to stand to defoam, resulting in liquid B with a mass concentration of 2‰. Liquid B and liquid A are mixed at a volume ratio of 3:1, and the initial setting time, slurry retention rate, and 1-hour compressive strength of liquid B are measured. The test results are as follows: the initial setting time of the mixture of liquid B and liquid A is 2.5 hours; the slurry retention rate of liquid B at a flowing water velocity of 1.2 m / s is 94%; and the initial 1-hour compressive strength of the mixed slurry is 0.7 MPa.

[0101] Example 2

[0102] The procedure is carried out as described in Example 1, except that the raw materials for liquid A include: 45 kg / m³ of slaked lime. 3 580 kg / m³ of fly ash 3Sodium-based bentonite 75 kg / m³ 3 1000 kg / m³ of sand 3 Polystyrene 2.0 kg / m 3 Silicon powder 2.3 kg / m 3 Hydroxypropyl methylcellulose 0.008 kg / m 3 300 kg / m³ of water 3 The initial setting time of liquid A is 4.8 h, the solidified body strength is 0.28 MPa at 1 day and 3.1 MPa at 28 days, the stone formation rate is 96%, and the slurry consistency is 10 cm.

[0103] The raw materials for solution B include: 26 L / m³ of water glass. 3 8 L / m³ of polyacrylamide solution (a mixed solution of polyacrylamide and water, concentration 8%) 3 The modified polycarboxylate obtained in Preparation Example 1 was 0.9 kg / m 3 52 L / m 3 The initial setting time of the mixture of liquid B and liquid A is 2.1 h. The slurry retention rate of liquid B is 94% when the water flow rate is 1.2 m / s. The compressive strength of the slurry after 1 h of initial setting is 0.8 MPa.

[0104] Example 3

[0105] The procedure was carried out as described in Example 1, except that 1.3 kg / m 3 The modified polycarboxylate obtained in Preparation Example 1 was completely replaced with 1.3 kg / m 3 The modified polycarboxylate obtained in Preparation Example 2.

[0106] Example 4

[0107] The procedure was carried out as described in Example 1, except that 1.3 kg / m 3 The modified polycarboxylate obtained in Preparation Example 1 was completely replaced with 1.3 kg / m 3 The modified polycarboxylate obtained in Preparation Example 3.

[0108] Comparative Example 1

[0109] The procedure was carried out as described in Example 1, except that the grouting slurry used was only liquid A, and the grouting volume per ring was 3.8 m. 3 Based on the volume, the raw materials for liquid A include: 55 kg / m³ of slaked lime. 3 fly ash 625 kg / m³ 3 Sodium-based bentonite 80 kg / m 3 1100 kg / m³ of sand 3 Polystyrene 2.3 kg / m3 2.7 kg / m³ of silicon powder 3 Hydroxypropyl methylcellulose 0.01 kg / m 3 310 kg / m³ of water 3 .

[0110] Comparative Example 2

[0111] The procedure was carried out as described in Example 1, except that the raw material for the grouting slurry was only liquid B, and the grouting volume per ring was 3.8 m. 3 Based on the volume, the raw materials for liquid B include: 40 L / m³ of water glass. 3 8 L / m³ of polyacrylamide solution (a mixed solution of polyacrylamide and water, concentration 8%) 3 The modified polycarboxylate obtained in Preparation Example 1 was 1.3 kg / m 3 56 L / m 3 .

[0112] Comparative Example 3

[0113] The procedure was carried out as described in Example 1, except that the raw materials for the grouting slurry included liquid A and liquid B, with a grouting volume of 3.8 m³ per ring. 3 Based on the volume, the raw materials for liquid A include: 30 kg / m³ of slaked lime. 3 fly ash 680 kg / m³ 3 Sodium-based bentonite 60 kg / m 3 1200 kg / m³ of sand 3 Polystyrene 1.0 kg / m 3 4 kg / m³ of silicon powder 3 Hydroxypropyl methylcellulose 0.02 kg / m 3 330 kg / m³ of water 3 ;

[0114] The raw materials for solution B include: 20 L / m³ of water glass. 3 Polyacrylamide solution (a mixed solution of polyacrylamide and water, concentration 8%) 3 L / m 3 The modified polycarboxylate obtained in Preparation Example 1 was 2.0 kg / m 3 56 L / m 3 .

[0115] Comparative Example 4

[0116] The procedure was carried out as described in Example 1, except that the raw materials for the grouting slurry included liquid A and liquid B, with a grouting volume of 3.8 m³ per ring. 3 Based on the volume, the raw materials for liquid A include: 70 kg / m³ of slaked lime. 3450 kg / m³ of fly ash 3 Sodium-based bentonite 100 kg / m 3 800 kg / m³ of sand 3 Polystyrene 3.0 kg / m 3 Silicon powder 1 kg / m 3 Hydroxypropyl methylcellulose 0.001 kg / m 3 280 kg / m³ of water 3 ;

[0117] The raw materials for solution B include: 50 L / m³ of water glass. 3 15 L / m³ of polyacrylamide solution (a mixture of polyacrylamide and water, concentration 8%) 3 The modified polycarboxylate obtained in Preparation Example 1 was 0.1 kg / m 3 56 L / m 3 .

[0118] Application Examples 1-3 and Comparative Examples 1-5 describe the application of the grouting slurry described in Examples 1-4 and Comparative Examples 1-4 in synchronous grouting during shield tunneling in steep slope sections of water-rich sandy gravel strata. The water-rich sandy gravel strata are the No. 1 construction area of ​​the Chengdu-Deyang line project, with a water content of 20-40%.

[0119] Application Example 1

[0120] A method for simultaneous grouting during shield tunneling in steep slope sections of water-rich sandy gravel strata, the method comprising the following steps:

[0121] S1. The tunnel boring machine first enters the flat area of ​​the water-rich sandy and gravelly strata for excavation. The A liquid described in Example 1 and the B liquid are mixed at a volume ratio of 4:1 and then injected into the ground. The grouting volume per ring is 3.8 m. 3 During construction, the soil pressure, slope, groundwater flow velocity, segment rolling angle, and grouting pressure are obtained in real time.

[0122] S2. Based on the real-time acquired earth pressure, slope, groundwater velocity, segment rolling angle and grouting pressure, a dynamic compensation model for grouting volume as described in equation (1) is constructed, wherein the initial slope value is 0 and the initial groundwater velocity is 0.1 m / s.

[0123] S3. The tunnel boring machine enters the uphill section. The real-time slope of the uphill section is measured to be 35‰, and the real-time groundwater flow velocity is 0.5m / s. According to formula (1), the total grouting volume of the uphill section is adjusted to 6.023 m³. 3The grouting slurry used in the upslope section is liquid A and liquid B as described in Example 1. The grouting holes in the upslope section include top grouting holes, bottom grouting holes, and side grouting holes. The total grouting volume of the upslope section is 100%, the grouting volume of the top grouting holes is 65%, the grouting volume of the bottom grouting holes is 25%, and the grouting volume of the side grouting holes is 10%. The grouting slurry used in the top grouting holes is a mixture of liquid A and liquid B with a mass ratio of 4:1. The grouting slurry used in the bottom grouting holes is a mixture of liquid A and liquid B with a mass ratio of 3:1. The grouting slurry used in the side grouting holes is a mixture of liquid A and liquid B with a mass ratio of 2:1. The grouting pressure of the top grouting holes is 0.45 MPa, the grouting pressure of the bottom grouting holes is 0.2 MPa, and the grouting pressure of the side grouting holes is 0.3 MPa.

[0124] The tunnel boring machine entered the downhill section, and the real-time slope of the downhill section was measured to be 32‰. The real-time groundwater flow velocity was 0.3 m / s. According to formula (1), the total grouting volume of the downhill section was adjusted to 5.738 m³. 3 The grouting slurry used in the downhill section is the mixture of liquid A and liquid B described in Example 2. The grouting holes in the downhill section include top grouting holes, bottom grouting holes, and side grouting holes. With the total grouting volume of the downhill section as 100%, the grouting volume of the top grouting holes is 30%, the grouting volume of the bottom grouting holes is 50%, and the grouting volume of the side grouting holes is 20%. The grouting slurry used in the top grouting holes is a mixture of liquid A and liquid B in a mass ratio of 5:1; the grouting slurry used in the bottom grouting holes is a mixture of liquid A and liquid B in a mass ratio of 3:1; and the grouting slurry used in the side grouting holes is a mixture of liquid A and liquid B in a mass ratio of 2:1. The grouting pressure of the top grouting holes is 0.25 MPa, the grouting pressure of the bottom grouting holes is 0.4 MPa, and the grouting pressure of the side grouting holes is 0.3 MPa.

[0125] Application Example 2

[0126] The application is carried out in the manner described in Example 1, except that liquid A and liquid B described in Example 1 are replaced with liquid A and liquid B described in Example 3.

[0127] Application Example 3

[0128] The application is carried out in the manner described in Example 1, except that liquid A and liquid B described in Example 1 are replaced with liquid A and liquid B described in Example 4.

[0129] Application Comparative Example 1

[0130] The application was carried out in the manner described in Example 1, except that the grouting slurry for both the uphill and downhill sections was completely replaced with the grouting slurry described in Comparative Example 1.

[0131] Application Comparative Example 2

[0132] The application was carried out in the manner described in Example 1, except that the grouting slurry for both the uphill and downhill sections was completely replaced with the grouting slurry described in Comparative Example 2.

[0133] Application Comparative Example 3

[0134] The application was carried out in the manner described in Example 1, except that the grouting slurry for both the uphill and downhill sections was completely replaced with the grouting slurry described in Comparative Example 3.

[0135] Application Comparative Example 4

[0136] The application was carried out in the manner described in Example 1, except that the grouting slurry for both the uphill and downhill sections was completely replaced with the grouting slurry described in Comparative Example 4.

[0137] Application Comparative Example 5

[0138] A method for simultaneous grouting during shield tunneling in steep slope sections of water-rich sandy gravel strata, the method comprising the following steps:

[0139] S1. The tunnel boring machine first enters the flat area of ​​the water-rich sandy and gravelly strata for excavation. The A liquid described in Example 1 and the B liquid are mixed at a volume ratio of 4:1 and then injected into the ground. The grouting volume per ring is 3.8 m. 3 ;

[0140] S2. The tunnel boring machine enters the uphill section and grouting is performed according to the foundation grouting volume. The grouting slurry for the uphill section uses liquid A and liquid B as described in Example 1. The grouting holes for the uphill section include top grouting holes, bottom grouting holes, and side grouting holes. Taking the total grouting volume of the uphill section as 100%, the grouting volume of the top grouting holes is 65%, the grouting volume of the bottom grouting holes is 25%, and the grouting volume of the side grouting holes is 10%. The grouting slurry used in the top grouting holes is a mixture of liquid A and liquid B in a mass ratio of 4:1; the grouting slurry used in the bottom grouting holes is a mixture of liquid A and liquid B in a mass ratio of 3:1; and the grouting slurry used in the side grouting holes is a mixture of liquid A and liquid B in a mass ratio of 2:1. The grouting pressure of the top grouting holes is 0.45. MPa, the grouting pressure of the bottom grouting hole is 0.2 MPa, and the grouting pressure of the side grouting hole is 0.3 MPa;

[0141] The tunnel boring machine (TBM) enters the downhill section, and grouting is performed according to the foundation grouting volume. The grouting slurry for the downhill section uses liquid A and liquid B as described in Example 2. The grouting holes for the downhill section include top grouting holes, bottom grouting holes, and side grouting holes. Taking the total grouting volume of the downhill section as 100%, the grouting volume of the top grouting holes is 30%, the grouting volume of the bottom grouting holes is 50%, and the grouting volume of the side grouting holes is 20%. The grouting slurry used in the top grouting holes is a mixture of liquid A and liquid B with a mass ratio of 5:1; the grouting slurry used in the bottom grouting holes is a mixture of liquid A and liquid B with a mass ratio of 3:1; and the grouting slurry used in the side grouting holes is a mixture of liquid A and liquid B with a mass ratio of 2:1. The grouting pressure for the top grouting holes is 0.25 MPa, and the grouting pressure for the bottom grouting holes is 0.4 MPa. MPa, the grouting pressure of the side grouting hole is 0.3 MPa.

[0142] The surface settlement rate of Application Examples 1-3 and Application Comparative Examples 1-5 was measured during the shield tunneling construction. After the shield tunneling construction was completed, the segment uplift and segment misalignment rate of the shield tunneling machines of Application Examples 1-3 and Application Comparative Examples 1-5 were measured, as well as the total surface settlement. The results are shown in Table 1.

[0143] Table 1

[0144]

[0145] As can be seen from the results in Table 1, the grouting slurry with specific components and proportions of this application can effectively solve the problem of anti-dispersion of slurry in water-rich environments. At the same time, when combined with the dynamic control model, it can effectively prevent the shield tunneling machine segments from floating when conducting shield tunneling in water-rich sandy gravel strata with steep slopes, thereby improving the tunnel forming quality and preventing disasters such as surface subsidence and rupture of adjacent pipelines.

[0146] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A grouting fluid suitable for shield tunneling in steep slope sections of water-rich sandy and gravelly strata, characterized in that, The raw materials for the grouting slurry include liquid A and liquid B, with a grouting volume of 3.8 m per ring. 3 Based on the volume, the raw materials for liquid A include: 40~60 kg / m³ of slaked lime. 3 fly ash 500~650 kg / m³ 3 Sodium-based bentonite 70~90 kg / m³ 3 Sand 900~1100 kg / m³ 3 Polystyrene 1.5~2.5 kg / m 3 Silicon powder 2~3 kg / m 3 Hydroxypropyl methylcellulose 0.005~0.01 kg / m 3 Water 300~320kg / m 3 The raw materials for solution B include: 25~40 L / m³ of water glass. 3 5~10 L / m of polyacrylamide solution 3 Modified polycarboxylate 0.5~1.5 kg / m 3 ; The preparation method of the modified polycarboxylate includes the following steps: (1) Polyethylene glycol monomethyl ether acrylate and water are mixed at 40~50 °C, and then the mixed system, acrylic acid and 2-acrylamide-2-methylpropanesulfonic acid are mixed to form a monomer mixture; (2) At 65~70 °C, an initiator solution is added dropwise to the monomer mixture to carry out a polymerization reaction. When the viscosity of the polymerization product is 800~1200 mPa·s, mercaptoacetic acid is added to the polymerization product, and the temperature is raised to 75~80 °C to carry out the reaction. After the reaction is completed, the temperature is lowered to 40~50 °C, and the pH value is adjusted to 6.0~7.

0. (3) The system after pH adjustment in step (2) is mixed with silane coupling agent and reacted, wherein the content of silane coupling agent is 1~2% based on the total mass of the system after pH adjustment as 100%; (4) Filter the reaction product in step (3) and spray dry the filtrate to obtain modified polycarboxylate.

2. The grouting slurry according to claim 1, characterized in that, The ratio of polyethylene glycol monomethyl ether acrylate, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, initiator solution and mercaptoacetic acid is 1 g: 10~12 mL: 3~6 g: 10~25 mL: 1~10 mL.

3. The grouting slurry according to claim 1, characterized in that, The fly ash is Class II fly ash, the fineness modulus of the sand is 0.5~1.5, the average particle size of the polystyrene is ≤50 μm, the SiO2 content in the silicon powder is ≥90%, and the viscosity of the hydroxypropyl methylcellulose is 20000~40000 mPa·s. The polyacrylamide solution is a mixture of anionic polyacrylamide and water, wherein the molecular weight of the anionic polyacrylamide is 8 million to 12 million.

4. A method for simultaneous grouting during shield tunneling in steep slope sections of water-rich sandy and gravelly strata, characterized in that, The method includes the following steps: S1. During the construction process, real-time construction data is acquired, including earth pressure, slope, groundwater flow velocity, segment rolling angle, and grouting pressure. S2. Construct a dynamic compensation model for grouting volume using the construction data. The dynamic compensation model for grouting volume is shown in equation (1): Q d = Q b ×[1 + K p ×(θ - θ0) + K v ×(v - v0)] Equation (1) In equation (1), Q d This represents the adjusted grouting volume. Q b This represents the amount of grout injected into the foundation before adjustment. K p Represents the slope compensation coefficient. K p The value is 0.015 / ‰. K v Represents the velocity compensation coefficient. K v The value is 0.1, θ represents the real-time slope value, θ0 represents the initial slope value, v represents the real-time groundwater flow velocity, and v0 represents the initial groundwater flow velocity. S3. Based on the dynamic compensation model for grouting volume and the real-time slope value and real-time groundwater flow velocity of the section to be grouted, the grouting volume of the section to be grouted during the construction process is dynamically adjusted. During the construction process, the grouting slurry used in the section to be grouted is the grouting slurry for shield tunneling construction in steep slope sections of water-rich sandy gravel strata as described in any one of claims 1 to 3.

5. The synchronous grouting method for shield tunneling in steep slope sections of water-rich sandy gravel strata according to claim 4, characterized in that, When the section to be grouted is an uphill section, the grouting holes of the uphill section include top grouting holes, bottom grouting holes, and side grouting holes. The total grouting volume of the uphill section is 100%, the grouting volume of the top grouting holes is 60-70%, the grouting volume of the bottom grouting holes is 20-30%, and the grouting volume of the side grouting holes is 5-15%.

6. The method for simultaneous grouting during shield tunneling in steep slope sections of water-rich sandy gravel strata according to claim 5, characterized in that, When the section to be grouted is a downhill section, the grouting holes in the downhill section include top grouting holes, bottom grouting holes, and side grouting holes. The total grouting volume of the downhill section is 100%, the grouting volume of the top grouting holes is 20-40%, the grouting volume of the bottom grouting holes is 40-60%, and the grouting volume of the side grouting holes is 10-30%.

7. The synchronous grouting method for shield tunneling in steep slope sections of water-rich sandy gravel strata according to claim 6, characterized in that, When the section to be grouted is an uphill section, the grout used in the top grouting hole is a mixture of liquid A and liquid B with a mass ratio of 3~5:1, the grout used in the bottom grouting hole is a mixture of liquid A and liquid B with a mass ratio of 2~4:1, and the grout used in the side grouting hole is a mixture of liquid A and liquid B with a mass ratio of 1~3:

1.

8. The method for simultaneous grouting during shield tunneling in steep slope sections of water-rich sandy and gravelly strata according to claim 6, characterized in that, When the section to be grouted is a downhill section, the grout used in the top grouting hole is a mixture of liquid A and liquid B with a mass ratio of 4~6:1, the grout used in the bottom grouting hole is a mixture of liquid A and liquid B with a mass ratio of 2~4:1, and the grout used in the side grouting hole is a mixture of liquid A and liquid B with a mass ratio of 1~3:

1.

9. The method for simultaneous grouting during shield tunneling in steep slope sections of water-rich sandy gravel strata according to claim 6, characterized in that, When the section to be grouted is an uphill section, the grouting pressure of the top grouting hole is 0.4~0.5 MPa, the grouting pressure of the bottom grouting hole is ≤0.2 MPa, and the grouting pressure of the side grouting hole is 0.3~0.35 MPa; When the section to be grouted is a downhill section, the grouting pressure of the top grouting hole is 0.25~0.3 MPa, the grouting pressure of the bottom grouting hole is 0.35~0.4 MPa, and the grouting pressure of the side grouting hole is 0.3~0.35 MPa.

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