A method and system for integrated construction of water-rich miscellaneous filling ground stratum tunnel portal upward slope section dewatering and grouting reinforcement

Abstract

The application provides a water-rich miscellaneous filling stratum tunnel portal upward slope section dewatering and pumping and grouting reinforcement integrated construction method and system, designs a set of dewatering and pumping and grouting combined construction control system, realizes the quick conversion of functions through a position switching mechanism by integrating drilling, pumping and grouting three functions of a main drill rod, adopts a "one hole multiple use, continuous operation" mode, immediately carries out grouting through the same borehole after pumping, avoids the secondary excavation and disturbance to the slope body, establishes a dynamic decision and regulation mechanism based on real-time monitoring data, judges the stratum characteristics in real time through the water yield change in the pumping stage, dynamically adjusts the grouting mix proportion parameters according to the stratum characteristics, and implements accurate control in the grouting process according to the pressure and flow feedback. Through integrated design and continuous operation, the "one hole multiple use, water treatment and reinforcement cooperation" is realized, so that the construction period is shortened, the cost is reduced, the secondary disturbance is avoided, and the reinforcement effect is improved.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering and tunnel construction technology, specifically relating to an integrated construction method and supporting system for dewatering and grouting reinforcement of the landslide section of the tunnel entrance slope in water-rich miscellaneous fill strata. Background Technology

[0002] In tunnel construction, the stability of the tunnel entrance slope directly affects construction safety and project progress. Miscellaneous fill, as a special type of unfavorable foundation soil, possesses engineering characteristics such as low bearing capacity, high permeability, and high compressibility. Especially under the influence of heavy rainfall, due to the poor uniformity of the miscellaneous fill strata, when a poorly permeable soil layer exists in the slope, it easily forms an impermeable layer, leading to localized waterlogging. Under hydraulic coupling, seepage from the slope forms a dynamic water-stagnant zone at the impermeable layer, continuously reducing the shear strength of the surrounding soil and ultimately causing slope collapse at the tunnel entrance, significantly increasing the safety risks during tunnel entrance construction.

[0003] In existing technologies, for tunnel entrance slope sections in water-rich, miscellaneous fill strata affected by landslides due to heavy rainfall, a separate construction process of "drainage first, grouting later" is often adopted. This process has the following main drawbacks: 1. Separation of processes, resulting in low efficiency: The drainage and grouting processes, which should be coordinated, are separated into two independent construction stages. This leads to the need to repeat preparatory work such as equipment arrival, drilling, and platform construction twice, causing the construction period to be extended significantly and affecting the critical path of the entire tunnel project. At the same time, the repeated equipment dispatch, installation and dismantling costs, drilling progress, and indirect costs such as labor, management, and equipment rental resulting from the extended construction period significantly increase the overall project cost. In addition, the need for two drillings and two equipment deployments at the same location results in a serious waste of manpower, materials, and machine shifts, which does not conform to the modern engineering concept of green and efficient operation. 2. Secondary disturbance and soil damage: Drainage construction itself causes initial disturbance to the slope. Subsequent grouting drilling and pressure grouting after drainage completion create secondary disturbance, damaging the already loose and fragile structure of the fill soil and becoming a direct human factor inducing settlement and landslides. 3. Lack of coordination and inconsistent reinforcement system: Drainage and grouting are implemented at different stages and under different conditions, lacking coordinated design and synergy in spatial location and timing. Preferred seepage channels may form around the drainage pipes, which subsequent grouting cannot effectively seal, resulting in poor integrity of the reinforced structure and ineffective waterproofing.

[0004] Therefore, there is an urgent need to develop a new technology and system for slope reinforcement that can integrate rainwater drainage and grouting reinforcement, avoid secondary disturbance, and improve construction efficiency. Summary of the Invention

[0005] To address the aforementioned deficiencies and shortcomings of existing technologies, this invention provides an integrated construction method and system for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich, miscellaneous fill strata. It transforms existing technical solutions, based on the bias of "high-pressure confrontation," into an innovative "drainage first, reinforcement later, dynamic adaptation" approach. This involves first efficiently draining water through integrated boreholes to reduce pore water pressure, while simultaneously using pumping and stratum permeability coefficients to diagnose stratum permeability in real time. Furthermore, it innovatively proposes a collaborative control mechanism for grouting pressure and grout mix ratio, along with dynamic adjustments and segmented grouting during the grouting process. This overcomes the technical bias of "pressurizing upon encountering water," achieving "multi-purpose use of a single borehole, synergistic water control and reinforcement," thereby shortening the construction period, reducing costs, avoiding secondary disturbances, and improving reinforcement effectiveness.

[0006] This invention also designs a combined construction control system for dewatering, pumping, and grouting. The main drill rod integrates drilling, pumping, and grouting functions, and a position switching mechanism enables rapid function switching. It adopts a "one-hole-multiple-use, continuous operation" mode, allowing grouting to be performed immediately after pumping, avoiding secondary excavation and disturbance to the slope. A dynamic decision-making and control mechanism based on real-time monitoring data is established. The system uses changes in water output during the pumping stage to determine geological characteristics in real time and dynamically adjusts the grouting mix ratio parameters accordingly. Precise control is implemented during grouting based on pressure and flow feedback.

[0007] The present invention is achieved using the following technical solution:

[0008] A method for integrating dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata includes the following steps:

[0009] Step 1: Determine the location, number, and grouting parameters of the integrated pumping and grouting operation holes based on the slope precipitation parameters and slope perimeter;

[0010] Step 2: Stabilize the slope by backfilling with soil at the leading edge of the landslide. Drill holes for integrated pumping and grouting operations at the outer edge of the slope top elevation above the landslide line.

[0011] Step 3: After drilling to the required depth, switch to pumping mode to pump water, monitor the water output L of a single borehole in real time, and obtain the formation permeability coefficient k based on the on-site survey; judge the formation permeability based on the formation permeability coefficient k and the monitored water output L of a single borehole, and dynamically adjust the grouting pressure and grout mix ratio accordingly.

[0012] Step 4: After the drainage is terminated, switch to grouting mode to carry out grouting operations. Divide the area below the water inflow line into several grouting points from bottom to top. Starting from the first grouting point, monitor the changes in flow rate and grouting pressure in real time, and dynamically control the termination of grouting and the lifting of the drill rod. When the lifting conditions are met, lift the drill rod to the next grouting point until the segmented grouting from bottom to top is completed.

[0013] The pumping and grouting operations in steps 3 and 4 can be carried out one hole at a time or multiple holes simultaneously until all holes have completed the pumping and grouting operations.

[0014] Furthermore, the integrated extraction and grouting operation holes are arranged in a staggered pattern using an equidistant hole layout.

[0015] Furthermore, the number of integrated extraction and grouting operation holes was determined. n The method is as follows: , Q Total water inflow for foundation pit dewatering (m³) 3 / d), the calculation method is: ,in, H 1 The thickness of the unconfined aquifer. S d Design the depth of groundwater level in the foundation pit. R The radius of influence of precipitation is calculated as follows: ; The equivalent radius of the precipitation area is calculated as follows: , A The area of ​​the foundation pit; q The single-hole water output (m³) 3 / d), the calculation method is: ; r The radius of the integrated extraction and grouting operation hole. l The effective length of the water inlet section of the integrated pumping and grouting operation hole; k The permeability coefficient of each soil layer is calculated as a weighted average based on the thickness of each soil layer. ,in k j The permeability coefficients of each soil layer; H j This represents the average thickness of each soil layer; H This represents the average total thickness of the overlying soil layer.

[0016] Based on the actual slope perimeter, the spacing between grouting holes is determined using the average well placement method. Different grout diffusion radii are flexibly designed according to the geological conditions at different locations. After determining the grouting radius, to maximize the effect of each grouting hole, a higher degree of overlap in the grout diffusion range between adjacent holes is achieved, thus ensuring uniform grouting of the formation.

[0017] Furthermore, the method for determining grouting parameters is as follows: overburden pressure , The overburden density is given by ρ, g is the acceleration due to gravity, and h is the thickness of the fill layer. Grouting pressure P2 = 2 × overburden pressure P. Design grouting pressure P1 = grouting pressure P2 - initial grouting loss pressure ΔP, where ΔP is the initial grouting loss pressure. Test well grouting is conducted at the engineering site, and the pressure-flow curve during the initial grouting stage is recorded. The maximum pressure loss value before pressure stabilization is taken. Q1 is the design grouting volume per well (m³). 3 ), , The grout filling coefficient is... denoted as grout loss coefficient; r1 as effective diffusion radius of grout; l as effective length of water inlet of integrated pumping and grouting operation hole; n as soil porosity; the mixing ratio of cement grout and water glass grout meets the requirements of initial setting time ≤ 60s and 28-day compressive strength ≥ 10MPa.

[0018] Furthermore, the method in step 3 for determining formation permeability based on the formation permeability coefficient k and the monitored single-well water output L, and dynamically adjusting the grouting pressure and grout mix ratio accordingly, is as follows:

[0019] When k>10m / d or L>120m 3 When the grouting pressure is / d, it is determined to be a high-permeability formation. The grouting pressure is increased by 20%-40% based on the design grouting pressure P1 to overcome the resistance of high-speed water flow in large pores. The volume ratio of cement grout to water glass is adjusted to 1:1.0-1:1.5. By increasing the proportion of water glass, the grout gelation is accelerated and excessive loss is prevented.

[0020] When 1m / d≤k≤10m / d or 12m 3 / d≤L≤120m 3 When the grouting pressure is / d, it is determined to be a medium-permeability formation. The grouting pressure is maintained at the design value, or slightly adjusted within ±10% above or below it. The volume ratio of cement grout to water glass is adjusted to 1:0.7-1:1.0 to achieve the grout balance diffusion and consolidation requirements.

[0021] When k < 1m / d or L < 12m 3 When the grouting pressure is / d, it is determined to be a low-permeability formation. The grouting pressure is reduced by 15%-30% based on the design grouting pressure P1 to avoid hydraulic fracturing that damages the original soil structure. The volume ratio of cement grout to water glass is adjusted to 1:0.4-1:0.7 to reduce the amount of water glass used, thereby extending the pumpable period of the grout and ensuring that it can penetrate into the micropores.

[0022] Furthermore, the threshold range and percentage adjustment of the formation permeability coefficient k and the monitoring single-well water output L can be empirically calibrated within ±20% according to specific engineering geological conditions.

[0023] Furthermore, in step 4, the method for dynamically controlling the termination of grouting and the lifting of the drill rod based on the dynamically adjusted grouting pressure and grout ratio, and according to the real-time monitoring of changes in flow rate and grouting pressure, is as follows:

[0024] The initial grouting flow rate is set to 15–25 L / min. When the grouting pressure reaches the dynamically adjusted grouting pressure and is stabilized for 3 to 5 minutes, the grouting flow rate drops to 7–8 L / min and remains stable for at least 5 to 10 minutes. If the conditions for lifting the drill rod are met, the rod lifting operation is carried out.

[0025] When the grouting pressure increases and the rate of pressure increase is greater than 0.1 MPa / min, and the grouting flow rate has dropped to less than 50% of the initial grouting flow rate, it is determined that there is a risk of pipe blockage. Pipeline inspection is carried out. If there is no blockage, the rod lifting operation is performed.

[0026] When the grouting pressure is lower than 50% of the dynamically adjusted grouting pressure for 3 to 5 minutes and the grouting flow rate increases to 26-28 L / min, grouting is paused and the drill rod is not lifted. The volume ratio of cement slurry to water glass is adjusted to increase the volume percentage of water glass in the mixed slurry by 10-30% to accelerate soil solidification. Then, grouting is resumed and the flow rate is reduced to 7-8 L / min. At the same time, the actual grouting pressure is monitored to see if it returns to the dynamically adjusted grouting pressure. Once the pressure returns to the dynamically adjusted grouting pressure and is stabilized for 3 to 5 minutes, the conditions for lifting the drill rod are met, and the rod lifting operation is performed.

[0027] When the grouting flow rate is lower than 50% of the initial flow rate for 5-8 minutes and the grouting pressure shows an upward trend, and grout appears to be seeping out of the borehole, it is determined that the conditions for lifting the drill rod are met, and the rod lifting operation is performed.

[0028] In this step, the area below the water inflow line will be divided into several grouting points from bottom to top. The number of grouting points will be determined according to the actual site conditions and will not affect the technical effect of the present invention.

[0029] Furthermore, it also includes step 5: after grouting is completed, the slope of the slope is reduced, local unstable fill is removed, and the overall stability of the slope is enhanced.

[0030] A combined dewatering, dewatering, and grouting reinforcement construction control system for the tunnel entrance slope section in water-rich miscellaneous fill strata, comprising: drilling equipment; a main drill rod including a casing, a core tube, and a position switching mechanism, wherein the casing and core tube can rotate relative to each other via the position switching mechanism; a water extraction pipe and a grouting pipe branching off from the main drill rod, wherein a water extraction valve and a water extraction pump, and a grouting valve and a grouting pump are respectively installed on the water extraction pipe and the grouting pipe to control the water extraction volume and the grouting volume respectively; the core tube has two external channels, a water extraction hole and a grouting hole, with the water extraction hole arranged within the core tube. The sidewall has grouting holes located at the bottom of the core tube. The sleeve has a water inlet corresponding to the water extraction hole, and the front end has a slot corresponding to the grouting hole. The sleeve and the core tube can rotate relative to each other through a position switching mechanism to achieve angular matching between the sleeve and the core tube, thus opening or closing the water inlet and water extraction hole for water extraction, and opening or closing the grouting hole for grouting. The grouting pipe is connected to the mixed slurry storage tank, which is connected to the cement slurry storage tank, the delivery pump, and the water glass storage tank and delivery pump, enabling real-time preparation of the mixed slurry. The mixed slurry storage tank is also equipped with a mixer.

[0031] Furthermore, the water extraction holes are evenly arranged on the side wall of the core tube at 120° intervals, the water extraction ports are evenly arranged on the side wall of the casing at 120° intervals, and the grouting holes are fan-shaped openings evenly arranged at 120° intervals at the bottom of the core tube; the front end of the casing has three slots corresponding to the grouting holes.

[0032] Furthermore, a sealing ring is used to seal the casing and the core tube, enabling the tubes to withstand positive and negative pressures, which is beneficial for pumping and grouting operations. It also includes a monitoring device, which includes a flow meter and a grouting pressure gauge. The flow meter is installed on the pumping pipeline, and the grouting pressure gauge is installed on the grouting pipeline, for real-time monitoring of pumping volume, grouting pressure, and grouting volume.

[0033] Compared with the prior art, the present invention has the following beneficial technical effects:

[0034] 1. Integrated design for improved efficiency: The combined construction control system designed in this invention integrates drilling, pumping, and grouting functions into the same main drill rod. Through the position switching mechanism, it can quickly switch functions to achieve "multi-purpose use of one hole and continuous operation". It combines the two traditionally separate construction stages into a continuous process, significantly shortens the construction period, reduces the costs of equipment dispatch, drilling, and labor, and greatly improves resource utilization.

[0035] 2. Avoid secondary disturbance and ensure safety: Pumping and grouting are carried out continuously through the same borehole, avoiding the secondary disturbance to the slope caused by drilling and grouting again after drainage in traditional methods. This effectively protects the original loose and fragile structure of the fill soil, reduces the risk of secondary landslides, and improves construction safety.

[0036] 3. Dynamic control and precise reinforcement: This invention establishes a dynamic decision-making mechanism based on real-time monitoring data. By analyzing the changes in water output and permeability coefficient during the pumping stage, the permeability and water-bearing characteristics of the formation are judged in real time, and the grouting mix ratio and pressure parameters are dynamically adjusted accordingly. During the grouting process, real-time control is based on pressure and flow feedback to achieve precise lifting and stopping of the grouting rod, ensuring that the grout effectively fills the target area, significantly improving the integrity of the reinforced body and the water-stopping effect.

[0037] 4. Wide range of applications: This invention is not only applicable to the reinforcement of tunnel entrance slopes, but can also be extended to the treatment of slope collapses in similar water-rich miscellaneous fill strata in municipal, construction, and transportation projects, and has broad application prospects.

[0038] Specifically, in the traditional practice of grouting reinforcement of water-rich strata, especially for loose and highly permeable strata such as miscellaneous fill, there has long been a common and deep-rooted technical bias among those skilled in the art: that the stronger the water-richness and the higher the permeability of the stratum, the more necessary it is to increase the grouting pressure to overcome the water flow resistance and force the grout to diffuse, thereby achieving the purpose of water stoppage and reinforcement. This mindset of "using high pressure to counteract water-richness" stems from a simple understanding of Darcy's law of seepage, that is, the belief that increasing the pressure gradient is the only direct means to improve the grout injection capacity. However, after in-depth research on the engineering characteristics of water-rich miscellaneous fill strata, this invention found that the above-mentioned traditional understanding has serious misconceptions, and is precisely one of the root causes of problems such as "secondary disturbance" and "poor reinforcement effect" in the existing technology: (1) Risk of structural damage: the miscellaneous fill structure is loose and has low strength. Blindly increasing the grouting pressure is very likely to produce a "hydraulic splitting" effect on the soil. Not only will it fail to achieve uniform filling, but it will also artificially create or expand cracks, forming new preferential seepage channels and destroying the stability of the slope. (2) Ineffective grout loss: When excessive pressure is applied in high-permeability formations, the grout (especially expensive two-component grout with controllable setting time) will be lost too quickly and too far along the existing large pore channels under pressure, and will not be able to stay, solidify and cement effectively in the target area, resulting in material waste and discontinuous solidification. (3) Lack of feedback mechanism: The traditional "drainage first and then grouting" separation process and the practice of setting a fixed grouting pressure completely ignore the spatial non-uniformity of formation permeability and the role of drainage process in revealing formation conditions.

[0039] Based on a profound reflection on and breakthrough of the above-mentioned technical biases, this invention proposes a different technical approach: for water-rich mixed fill strata, the key to successful grouting is not simply increasing the pressure, but achieving "drainage and pressure reduction, and precise matching". This invention overcomes the technical biases in the prior art and achieves unexpected technical effects: (1) Core concept transformation: from "high pressure confrontation" to "drainage first and then consolidation, dynamic adaptation", that is, firstly, efficient drainage is achieved through integrated drilling to reduce pore water pressure, while at the same time, the permeability of the strata is diagnosed in real time using pumping data. (2) Innovatively, a collaborative control technical strategy is proposed, and an effective control scheme is provided: the grouting pressure and grout ratio are dynamically adjusted according to the diagnostic results. For high-permeability formations, while moderately increasing the grouting pressure (20%~40%), the grout ratio is adjusted simultaneously to control the setting rate and prevent loss; for low-permeability formations, the grouting pressure is actively reduced (15%-30%) and the amount of water glass in the grout ratio is reduced simultaneously to extend the pumpable period of the grout and ensure that it can penetrate into the micropores; this strategy of "pressure-ratio" coordinated control breaks the traditional dogma and technical prejudice of "increasing pressure when encountering water". (3) Innovatively, a dynamic adjustment and segmented grouting effective technical solution is proposed: during the grouting process, the lifting rod operation and the stopping grouting operation are dynamically adjusted according to the grouting pressure and flow rate, and a specific and clear control strategy is provided. Compared with the existing grouting scheme, this dynamic adjustment strategy ensures the completion of segmented grouting from bottom to top and full hole filling, avoiding uneven and incomplete grouting, which affects the overall reinforcement effect. (4) Integrated synergistic advantages: This invention completes drainage and grouting in the same borehole and continuous operation, ensuring "zero time difference" linkage between diagnostic information and execution actions, enabling dynamic control, which is something that the separate process in the prior art cannot achieve.

[0040] Therefore, this invention overcomes the technical prejudice that "high-pressure grouting must be used in water-rich strata" and provides an innovative core concept and a more scientific, safer and more economical integrated solution with specific and effective synergistic control technology strategies, resulting in shorter construction period, avoidance of secondary disturbance and improved reinforcement effect. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the combined construction control system for dewatering, drainage, and grouting.

[0042] The components are as follows: 1-Drilling equipment, 2-Main drill rod, 3-Casing, 4-Core tube, 5-Position switching mechanism, 6-Water pumping pipe, 7-Grouting pipe, 8-Water pumping valve, 9-Water pump, 10-Grouting valve, 11-Grouting pump, 12-Water pumping hole, 13-Grouting hole, 14-Water pumping outlet, 15-Grooving, 16-Mixed slurry storage tank, 17-Cement slurry storage tank, 18-Cement slurry delivery pump, 19-Water glass storage tank, 20-Water glass delivery pump, 21-Agitator, 22-Grouting pressure gauge, 23a-Flow meter one, 23d-Flow meter two, 23b-Flow meter three, 23d-Flow meter four, 24-Casing front end.

[0043] Figure 2 A schematic diagram of the main drill pipe assembly;

[0044] Figure 3 A schematic diagram of the layout of the water pumping holes and grouting holes in the main drill pipe core tube, and a cross-sectional view of the main drill pipe.

[0045] Figure 4 This is a schematic diagram showing the opening and closing states of the pumping and grouting ports when the switching mechanism is rotating.

[0046] Figure 5 This is a schematic diagram of the rainwater pumping and drainage construction.

[0047] Figure 6a , Figure 6b , Figure 6c This is a schematic diagram of the grouting process;

[0048] Figure 7 This is a schematic diagram of construction step 5 - slope reduction;

[0049] Figure 8 A schematic diagram of the plum blossom-shaped arrangement of the integrated extraction and grouting operation holes. Detailed Implementation

[0050] The present invention will now be further described with reference to embodiments. It should be understood that the preferred embodiments described herein are preferred embodiments.

[0051] Examples are used only to illustrate and explain the invention and are not intended to limit the invention.

[0052] Example 1

[0053] A method for integrating dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata includes the following steps:

[0054] Step 1: Determine the location, number, and grouting parameters of the integrated pumping and grouting operation holes based on the slope precipitation parameters and slope perimeter.

[0055] The aquifer thickness and borehole depth are obtained from preliminary exploration work. Various mature existing technologies can be employed. For example, during preliminary exploration, the elevation of the actual water inflow point (the unconfined aquifer) on the actual slope section of the borehole entrance can be determined by on-site surveys and existing technologies such as on-site water injection tests. This allows the determination of the unconfined aquifer thickness within the slope body, and the borehole depth is then determined based on the unconfined aquifer thickness and the distance from the slope crest. The slope precipitation parameters and slope perimeter can also be obtained from preliminary exploration work. Therefore, the number of integrated pumping and grouting operation boreholes can be determined using various mature existing technologies.

[0056] The integrated extraction and grouting operation holes are laid out using an equidistant hole layout method, with the spacing determined according to the average well layout method and arranged in a quincunx pattern. Different grout diffusion radii are flexibly designed based on the formation conditions at different locations. After determining the grouting radius, to maximize the effect of each grouting hole, a higher degree of overlap in the grout diffusion range between adjacent holes is achieved, thus realizing the goal of uniform grouting of the formation.

[0057] The method for determining grouting parameters is: overburden pressure. , Where is the natural density of the overburden layer, g is the gravitational acceleration, h is the thickness of the fill layer, grouting pressure P2 = 2 × overburden pressure P, design grouting pressure P1 = grouting pressure P2 - initial grouting loss pressure ΔP, ΔP is the initial grouting loss pressure. In this embodiment, grouting is carried out in test holes on the engineering site, and the pressure-flow curve of the initial grouting stage is recorded. The maximum pressure loss value before the pressure stabilizes is taken, which is 0.1-0.2 MPa.

[0058] Q 1 represents the design grouting volume per hole (m³). 3 ), , The grout filling coefficient is... This is the slurry loss coefficient; r 1 represents the effective diffusion radius of the grout, which is the farthest distance that the grout can effectively diffuse in the pores or fissures of the rock and soil under a certain pressure and achieve the expected reinforcement or seepage prevention effect. The determination method is based on the "Grouting Technology Specification" (YS / T5211-2018) and is determined by field tests. Specifically, in important or geologically complex projects, grouting tests are conducted in representative areas on site, and the actual diffusion range that meets the quality requirements is directly measured through drilling grouting, sampling and testing and other means. l The effective length of the water inlet section of the integrated pumping and grouting operation hole; n The soil porosity is specified; the ratio of cement grout to water glass grout meets the requirements of initial setting time ≤ 60 seconds and 28-day compressive strength ≥ 10 MPa.

[0059] Step 2: Stabilize the slope by backfilling with soil at the leading edge of the landslide and drilling at the outer edge of the slope top elevation above the landslide line until the drilling depth is reached.

[0060] Step 3: After drilling to the designated depth, switch to pumping mode for pumping operations. Monitor the single-hole water output L in real time, record the pumping volume change curve over time, and determine the formation permeability based on the formation permeability coefficient k obtained from the field survey. Adjust the grouting pressure and grout mix ratio dynamically accordingly, specifically: when k > 10 m / d or L > 120 m... 3 When the grouting pressure is 1m / d, it is determined to be a high-permeability formation. The grouting pressure is increased by 20%-40% based on the design grouting pressure P1 to overcome the resistance of high-speed water flow in large pores. The volume ratio of cement grout to water glass is adjusted to 1:1.0-1:1.5 to accelerate grout gelation and prevent excessive loss by increasing the proportion of water glass. When 1m / d≤k≤10m / d or 12m 3 / d≤L≤120m 3 When k < 1 m / d, the formation is classified as medium permeability. The grouting pressure should be maintained at the design value, or adjusted slightly within ±10% above or below it. The volume ratio of cement grout to water glass should be adjusted to 1:0.7-1:1.0 to achieve balanced diffusion and consolidation of the grout. When k < 1 m / d or L < 12 m... 3 When the grouting pressure is / d, it is determined to be a low-permeability formation. The grouting pressure is reduced by 15%-30% based on the design grouting pressure P1 to avoid hydraulic fracturing that damages the original soil structure. The volume ratio of cement grout to water glass is adjusted to 1:0.4-1:0.7 to reduce the amount of water glass used, thereby extending the pumpable period of the grout and ensuring that it can penetrate into the micropores.

[0061] Formation permeability coefficients can be directly determined through in-situ surveys (in-situ testing). Various mature methods available in the field can be used for this purpose. According to the "Standard for Geotechnical Engineering Investigation," pumping tests, injection tests, and pressure tests can be employed. In this embodiment, the pumping test method is used to determine the k-value. This involves setting up observation wells at different distances from the main well and measuring the pumping rate and drawdown under steady-state conditions. If the formation is not a type of formation, then k is the weighted average of the permeability coefficients of each formation based on its thickness, calculated as follows: , where kj is the permeability coefficient of each stratum; Hj is the average thickness of each stratum, determined according to the geological survey report; and H is the average total thickness of the overlying soil layer.

[0062] Step 4: After the drainage is terminated, switch to grouting mode for grouting operations. Divide the area below the water inflow line into several grouting points from bottom to top. Starting from the first grouting point, based on the grouting pressure and grout mix ratio dynamically adjusted in Step 3 according to the formation permeability coefficient k and the monitored single-hole outflow L, monitor the flow rate and grouting pressure changes in real time to dynamically control the termination of grouting and the lifting of the drill rod. When the lifting conditions are met, lift the drill rod to the next grouting point until the bottom-up segmented grouting and full hole filling are completed. Specifically:

[0063] The initial grouting flow rate is set to 15–25 L / min. When the grouting pressure reaches the dynamically adjusted grouting pressure and is stabilized for 3 to 5 minutes, the grouting flow rate drops to 7–8 L / min and remains stable for at least 5 to 10 minutes. If the conditions for lifting the drill rod are met, the rod lifting operation is carried out.

[0064] When the grouting pressure increases and the rate of pressure increase is greater than 0.1 MPa / min, and the grouting flow rate has dropped to less than 50% of the initial grouting flow rate, it is determined that there is a risk of pipe blockage. Pipeline inspection is carried out. If there is no blockage, the rod lifting operation is performed.

[0065] When the grouting pressure is lower than 50% of the dynamically adjusted grouting pressure for 3 to 5 minutes and the grouting flow rate increases to 26-28 L / min, grouting is paused and the drill rod is not lifted. The volume ratio of cement slurry to water glass is adjusted to increase the volume percentage of water glass in the mixed slurry by 10-30% to accelerate soil solidification. Then, grouting is resumed and the flow rate is reduced to 7-8 L / min. At the same time, the actual grouting pressure is monitored to see if it returns to the dynamically adjusted grouting pressure. Once the pressure returns to the dynamically adjusted grouting pressure and is stabilized for 3 to 5 minutes, the conditions for lifting the drill rod are met, and the rod lifting operation is performed.

[0066] When the grouting flow rate is lower than 50% of the initial flow rate for 5-8 minutes and the grouting pressure shows an upward trend, and grout appears to be seeping out of the borehole, it is determined that the conditions for lifting the drill rod are met, and the rod lifting operation is performed.

[0067] The pumping and grouting operations in steps 3 and 4 are carried out one hole at a time until all holes have been pumped and grouted.

[0068] Example 2

[0069] Compared with Example 1, the difference in this example is that: in step 1, the number of integrated drainage and grouting operation holes is determined based on the slope precipitation parameters and slope perimeter, and the number n of the integrated drainage and grouting operation holes is: Q is the total inflow of water from the foundation pit (m³). 3 / d), the calculation method is: Where H1 is the thickness of the unconfined aquifer, s dThe design drawdown depth for the groundwater level in the foundation pit, where R is the radius of influence of the drawdown, is calculated as follows: ; The equivalent radius of the precipitation area is calculated as follows: A is the area of ​​the foundation pit; q is the water output per single hole (m³). 3 / d), the calculation method is: ; r is the radius of the integrated pumping and grouting operation hole, which is 0.15m in this embodiment based on the operation hole used; l is the effective length of the water inlet of the integrated pumping and grouting operation hole, which is determined considering the dewatering process and site geology of this project, and is 4.5m in this embodiment; k is the weighted average of the permeability coefficient of each soil layer according to the soil layer thickness, and is calculated as follows: , where k j H represents the permeability coefficient of each soil layer. j The average thickness of each soil layer is determined according to the geological survey report; H is the average total thickness of the overlying soil layer.

[0070] Based on the actual slope perimeter, the integrated drainage and grouting operation holes are laid out using an equidistant hole layout method. The spacing is determined according to the average well layout method, and a quincunx pattern is adopted. In this implementation, if... Figure 8 As shown, every three integrated extraction and grouting operation holes are arranged in a plum blossom pattern. For the remaining holes that are less than three, the remaining holes are arranged according to the method of equal spacing.

[0071] Step 2: Fill soil at the leading edge of the landslide to stabilize the slope, and carry out drilling operations at the outer edge of the slope top elevation more than 5m away from the landslide line until the drilling depth is reached.

[0072] Example 3

[0073] Compared with Examples 1 and 2, this embodiment also includes step 5: after grouting, the slope ratio of the slope is adjusted from 1:1 to 1:1.5, local unstable fill is removed, and the overall stability of the slope is enhanced.

[0074] Example 4

[0075] The difference between this embodiment and Embodiment 1 is that:

[0076] In the method for determining grouting parameters, ΔP represents the initial grouting loss pressure. This is achieved by grouting test holes at the engineering site, recording the pressure-flow curve during the initial grouting stage, and taking the maximum pressure loss value before pressure stabilization. In this embodiment, this value is 0.1 MPa. The initial setting time of the cement grout and water glass two-component grout is 60 seconds, and the 28-day compressive strength is 10 MPa.

[0077] In step 3: when the k obtained from the on-site investigation is 12 m / d, or the monitored single-well outflow L is maintained at 121 m... 3When the grouting pressure is / d, it is determined to be a high-permeability formation. The grouting pressure is increased by 20% based on the design pressure, and the volume ratio of cement grout to water glass is adjusted to 1:1.0. When the field survey yields k = 1m / d or the monitoring single-well outflow L = 12m 3 When the grouting pressure is / d, it is determined to be a medium-permeability formation, and the grouting pressure is reduced by 10% from the design grouting pressure; the volume ratio of cement grout to water glass is adjusted to 1:0.7 to achieve the grout balance diffusion and consolidation requirements; when the field investigation yields k = 0.8m / d or L = 10m 3 When the grouting pressure is / d, it is determined to be a low-permeability formation. The grouting pressure is reduced by 15% based on the design grouting pressure P1 to avoid hydraulic fracturing that could damage the original structure of the soil. The volume ratio of cement grout to water glass is adjusted to 1:0.7 to reduce the amount of water glass used, thereby extending the pumpable period of the grout and ensuring that it can penetrate into the micropores.

[0078] In step 4: the initial grouting flow rate is set to 15 L / min. When the grouting pressure reaches the adjusted grouting pressure and is stabilized for 3 minutes, the grouting flow rate is reduced to 7 L / min and stabilized for at least 5 minutes. This is considered to meet the drill rod lifting conditions, and the rod lifting operation is performed. When the grouting pressure increases and the pressure rise rate is 0.2 MPa / min, while the grouting flow rate has dropped to 7.5 L / min, it is considered that there is a risk of pipe blockage. The pipeline is checked, and no blockage is found. The rod lifting operation is then performed. When the grouting pressure is 50% of the adjusted grouting pressure for 3 minutes and the grouting flow rate increases to 26 L / min, grouting is paused and the drill rod is not lifted. The volume ratio of cement slurry to water glass is adjusted to increase the volume percentage of water glass in the mixed slurry by 10% to accelerate soil solidification. Then, grouting is resumed and the flow rate is controlled to be reduced to 7 L / min. At the same time, the grouting pressure is monitored. When the adjusted grouting pressure is restored and stabilized for 3 minutes, it is considered to meet the drill rod lifting conditions, and the rod lifting operation is performed.

[0079] When the grouting flow rate is consistently below 7.5 L / min for 5 minutes and the grouting pressure shows an upward trend, and grout appears to be seeping out of the borehole, the conditions for lifting the drill rod are deemed met, and the rod lifting operation is executed.

[0080] Example 5

[0081] The difference between this embodiment and Embodiment 1 is that:

[0082] In the method for determining grouting parameters, ΔP represents the initial grouting loss pressure. This is achieved by grouting test holes at the engineering site, recording the pressure-flow curve during the initial grouting stage, and taking the maximum pressure loss value before pressure stabilization. In this embodiment, this value is 0.2 MPa. The mixing ratio of cement grout and water glass grout is consistent with an initial setting time of 40 seconds and a 28-day compressive strength of 20 MPa.

[0083] In step 3: when k is 15m / d or L is 125m3 When k is 5 m / d, the formation is identified as highly permeable. The grouting pressure is increased by 30% based on the design grouting pressure P1 to overcome the resistance of high-speed water flow in large pores. The volume ratio of cement grout to water glass is adjusted to 1:1.2 to accelerate grout gelation and prevent excessive loss by increasing the proportion of water glass. When k is 5 m / d or L is 50 m... 3 When k is 0.5 m / d, the formation is classified as medium permeability, and the grouting pressure remains at the design value. The volume ratio of cement grout to water glass is adjusted to 1:0.8 to achieve the required grout balance diffusion and consolidation. When k is 0.5 m / d or L is 8 m... 3 When the grouting pressure is / d, it is determined to be a low-permeability formation. The grouting pressure is reduced by 20% based on the design grouting pressure P1 to avoid hydraulic fracturing that could damage the original structure of the soil. The volume ratio of cement grout to water glass is adjusted to 1:0.6 to reduce the amount of water glass used, thereby extending the pumpable period of the grout and ensuring that it can penetrate into the micropores.

[0084] In step 4: the initial grouting flow rate is set to 25 L / min. When the grouting pressure reaches the adjusted grouting pressure and is stabilized for 5 minutes, the grouting flow rate is reduced to 8 L / min and stabilized for at least 10 minutes. This is considered to meet the drill rod lifting conditions, and the rod lifting operation is performed. When the grouting pressure increases and the pressure rise rate is 1 MPa / min, while the grouting flow rate has dropped to 12.5 L / min, it is considered that there is a risk of pipe blockage. The pipeline is inspected, and if a blockage is found, it is cleared. Grouting continues. When the grouting pressure is lower than 50% of the adjusted grouting pressure for 5 minutes and the grouting flow rate increases to 28 L / min, grouting is paused and the drill rod is not lifted. The volume ratio of cement slurry to water glass is adjusted to increase the volume percentage of water glass in the mixed slurry by 30% to accelerate soil solidification. Then, grouting is resumed and the flow rate is controlled to be reduced to 8 L / min. At the same time, the grouting pressure is monitored until it is restored to the adjusted grouting pressure and stabilized for 5 minutes. This is considered to meet the drill rod lifting conditions, and the rod lifting operation is performed.

[0085] When the grouting flow rate is consistently below 12.5 L / min for 8 minutes and the grouting pressure shows an upward trend, and grout leakage occurs at the borehole opening, the conditions for drill rod lifting are deemed met, and the rod lifting operation is executed.

[0086] Example 6

[0087] The difference between this embodiment and Embodiment 1 is that:

[0088] In the method for determining grouting parameters, ΔP represents the initial grouting loss pressure. This is achieved by grouting test holes at the engineering site, recording the pressure-flow curve during the initial grouting stage, and taking the maximum pressure loss value before pressure stabilization. In this embodiment, this value is 0.15 MPa. The mixing ratio of cement grout and water glass grout meets the requirements of an initial setting time of 20 seconds and a 28-day compressive strength of 30 MPa.

[0089] In step 3: when k is 20m / d or L is 130m 3 When k is 10 m / d, the formation is identified as highly permeable. The grouting pressure is increased by 40% based on the design grouting pressure P1 to overcome the resistance of high-speed water flow in large pores. The volume ratio of cement slurry to water glass is adjusted to 1:1.5 to accelerate slurry gelation and prevent excessive loss by increasing the proportion of water glass. When k is 10 m / d or L is 120 m... 3 When k is 0.3 m / d, the formation is classified as medium permeability, and the grouting pressure is increased by 10% from the design value; the volume ratio of cement grout to water glass is adjusted to 1:1.0 to achieve balanced diffusion and consolidation of the grout; when k is 0.3 m / d or L is 5 m 3 When the soil is classified as a low-permeability formation, the grouting pressure is reduced by 30% from the design grouting pressure P1 to avoid hydraulic fracturing that could damage the original soil structure. The volume ratio of cement grout to water glass is adjusted to 1:0.4 to reduce the amount of water glass used, thereby extending the pumpable period of the grout and ensuring that it can penetrate into the micropores.

[0090] In step 4: the initial grouting flow rate is set to 20 L / min. When the grouting pressure reaches the adjusted grouting pressure and is stabilized for 4 minutes, the grouting flow rate is reduced to 7.5 L / min and stabilized for at least 8 minutes. This is considered to meet the drill rod lifting conditions, and the rod lifting operation is performed. When the grouting pressure increases and the pressure rise rate is 0.8 MPa / min, while the grouting flow rate has dropped to 10 L / min, it is considered to be at risk of pipe blockage. A pipeline inspection is performed, and no blockage is found. The rod lifting operation is then performed. When the grouting pressure is lower than 50% of the adjusted grouting pressure for 4 minutes and the grouting flow rate increases to 27 L / min, grouting is paused and the drill rod is not lifted. The volume ratio of cement slurry to water glass is adjusted to increase the volume percentage of water glass in the mixed slurry by 20% to accelerate soil solidification. Then, grouting is resumed and the flow rate is reduced to 7.5 L / min. The grouting pressure is monitored until it is restored to the adjusted grouting pressure and stabilized for 4 minutes. This is considered to meet the drill rod lifting conditions, and the rod lifting operation is then performed.

[0091] When the grouting flow rate is consistently below 10 L / min for 7 minutes and the grouting pressure shows an upward trend, and grout leakage occurs at the borehole opening, the conditions for drill rod lifting are deemed met, and the rod lifting operation is executed.

[0092] Example 7

[0093] This embodiment describes the specific implementation of the present invention in detail with a specific engineering implementation plan.

[0094] The tunnel entrance has a vertical slope difference of 36m, with an original design slope ratio of 1:1. The slope is covered by 10-38m thick loose fill and plain fill, underlying strongly to moderately weathered granite. After 6 hours of heavy rainfall (cumulative rainfall of 70-80mm), the slope experienced a volume change of approximately 2000m³.3 The landslide revealed that the fill soil contained a large amount of construction waste. Subsequent investigation found that the fill soil layer had low bearing capacity (90 kPa) and a high permeability coefficient (8.0 m / d); the underlying silty clay layer had a permeability coefficient of only 0.01 m / d, forming a perched water layer; large-scale water inrush occurred at elevations of 88m and 87m, with a total inrush volume of approximately 2700 m³. 3 .

[0095] Step 1: Water-rich area detection and parameter determination. Transient electromagnetic method and ground-penetrating radar were used to detect the slope section (area 25754m²). 2 A joint survey was conducted, with 16 survey lines totaling 700m in length. The survey results show:

[0096] At points 20-38 on survey line N3, at depths of 11-18m, the apparent resistivity was 140 Ω·m. Ground-penetrating radar showed a phase axis misalignment accompanied by low-frequency oscillations, indicating a water-rich anomaly area. In the area between survey lines N5 and N8, at depths of 20-37m, the apparent resistivity was 120-210 Ω·m. The two anomaly areas showed good connectivity, indicating a major water-rich area. The final delineated overlapping area totaled approximately 1200 m². 2 This area is designated as a priority processing zone.

[0097] Water injection tests were conducted to determine the aquifer thickness: 26 boreholes were drilled on the upslope, with a spacing of 8-15m. A segmented, top-down plugging water injection test was performed: the permeability coefficient was measured in the 8-12m depth section (mixed fill area). K =8.29 m / d; in the 18-20m depth section (silty clay layer), the permeability coefficient K was measured to be 0.008 m / d, which is lower than the standard for impermeable layers specified in GB50487-2008. K <1×10 - 6 cm / s≈0.0086 m / d); drawing depth - K The groundwater level curve shows a clear inflection point at a depth of 18m, determining the top elevation of the unconfined aquifer to be 70m. The on-site measured groundwater level on the slope is 88m; therefore, the thickness of the unconfined aquifer is... H 1 is 18m.

[0098] Calculation of precipitation parameters: Based on the survey report, the area of ​​the foundation pit... A =25754m 2 Total thickness of overlying soil layer H =20.81m, weighted average permeability coefficient K =8.29 m / d; the radius of influence of precipitation is , H 1 represents the thickness of the unconfined aquifer, taken as 18m; s d The design drawdown depth for the groundwater level in the foundation pit is taken as 13.5m. The radius of influence of the drawdown is calculated.R The total precipitation inflow was 329.94m. The total precipitation inflow was calculated to be 4706.42 m³. 3 / d; Single-hole water output The calculated single-hole outflow rate is 513.77 m³. 3 / d; Number of integrated extraction and grouting operation holes Rounded down to 11.

[0099] Grouting parameter design: Grouting pressure: Overburden layer thickness h is 20m, density... 1.8 g / cm 3 g is the acceleration due to gravity, taken as 9.79 m / s². 2 Calculate the pressure of the overfill soil. =0.29MPa, the required grouting pressure is calculated to be 0.58MPa, which is twice the pressure of the overlying fill. Considering the pressure loss ΔP, it is taken as 0.2MPa in this embodiment, so the design grouting pressure is 0.78MPa. Grouting volume: calculate, The grout filling coefficient is set to 0.5. The grout loss coefficient is taken as 1.2; r1 is the effective diffusion radius of the grout, taken as 1.1m; l is the effective length of the water inlet of the integrated pumping and grouting operation hole, taken as 20m; n is the soil porosity, taken as 0.3. The calculated grouting volume Q1 per hole is 13.68m³. 3 The two-component slurry ratio was determined through indoor testing and comparison to be 1:0.5, with an initial setting time of 11 seconds and a 28-day compressive strength of 14.51 MPa.

[0100] Step 2: Drilling and Pumping Operations. Eleven dewatering pumping grouting holes are arranged in a staggered pattern (three holes per hole) along a 157m perimeter of the slope. The remaining two holes are then spaced evenly within the slope. The borehole diameter is Φ300mm, and the depth is 25m (5m into the permeable layer). Each hole has a flow rate of 25m³ / h. 3 A submersible pump with a flow rate of / h and a head of 28m. Pumping continued for 7 days.

[0101] Step 3: Dynamic Adjustment and Implementation of Grouting Parameters. Based on the pumping volume and the k-value characteristics obtained from on-site exploration, different grouting strategies are adopted: Hole 1 (high permeability): The grouting pressure is increased by 20% from the design pressure, i.e., from 0.78 MPa to 0.936 MPa, the volume ratio of cement grout to water glass is adjusted to 1:1.0, and the grouting speed is controlled at 5-8 L / min; Hole 5 (medium permeability): The grouting pressure is maintained at 0.78 MPa, the volume ratio of cement grout to water glass is 1:0.7, and the grouting speed is 10-12 L / min; Hole 9 (low permeability): The grouting pressure is reduced to 0.663 MPa, the volume ratio of cement grout to water glass is adjusted to 1:0.7, the amount of water glass is reduced to extend the pumpable period of the grout, ensuring that it can penetrate into the micropores, and the grouting speed is 3-5 L / min. Other holes can be adjusted accordingly using the following strategy: when k>10 m / d or L>120 m 3 When the grouting pressure is 1m / d, it is determined to be a high-permeability formation, and the grouting pressure is increased by 20%-40% based on the design grouting pressure P1; the volume ratio of cement grout to water glass is adjusted to 1:1.0-1:1.5; when 1m / d≤k≤10m / d or 12m 3 / d≤L≤120m 3 When k < 1 m / d, the formation is classified as medium permeability, and the grouting pressure is maintained at the design grouting pressure P1 or ±10%; the volume ratio of cement grout to water glass is adjusted to 1:0.7-1:1.0; when k < 1 m / d or L < 12 m 3 When the grouting pressure is / d, it is determined to be a low-permeability formation. The grouting pressure is reduced by 15%-30% based on the design grouting pressure P1; the volume ratio of cement grout to water glass is adjusted to 1:0.4-1:0.7.

[0102] Step 4: After the drainage is terminated, switch to grouting mode for grouting operations. Divide the area below the water inflow line of Hole 1 into five grouting points from bottom to top. Starting from the first grouting point, monitor the flow rate and grouting pressure changes in real time, and dynamically control the termination of grouting and the lifting of the drill rod. When the lifting conditions are met, lift the drill rod to the next grouting point until the bottom-up segmented grouting and full hole filling are completed. Specifically: The initial grouting flow rate is set to 25L / min. When grouting is performed in the first grouting hole, according to the real-time monitoring data, if the grouting pressure reaches the adjusted grouting pressure value of 0.936MPa and remains stable for 3 minutes, and the grouting flow rate drops to 7L / min and remains stable for 6 minutes, it is determined that the drill rod lifting conditions are met, and the lifting operation is performed, raising the drill rod to the height of the second grouting hole.

[0103] During the grouting operation in the second grouting hole, according to the real-time monitoring data, the grouting pressure reached the adjusted grouting pressure value of 0.936MPa and remained stable for 5 minutes, and the grouting flow rate dropped to 8L / min and remained stable for 7 minutes. It was determined that the conditions for lifting the drill rod were met, and the rod lifting operation was carried out to lift the drill rod to the height of the third grouting hole.

[0104] During grouting at the third grouting hole, real-time monitoring data showed that the grouting pressure dropped to 0.45 MPa, which was 50% below the adjusted grouting pressure of 0.936 MPa for 4 minutes, and the flow rate increased to 27.5 L / min. At this point, grouting was paused and the drill rod was not lifted. The volume ratio of cement slurry to water glass was adjusted to increase the volume percentage of water glass in the mixed slurry by 20% to accelerate soil solidification. Grouting was then resumed and the flow rate was reduced to 8 L / min. The grouting pressure was monitored. After the pressure returned to the adjusted grouting pressure of 0.936 MPa and was stabilized for 5 minutes, it was determined that the conditions for lifting the drill rod were met. The rod lifting operation was then performed, and the drill rod was lifted to the height of the fourth grouting hole.

[0105] During the grouting operation at the fourth grouting hole, real-time monitoring data showed that the grouting pressure increased at a rate of 0.2 MPa / min, while the grouting flow rate dropped to 12 L / min. This indicated a risk of pipe blockage, so a pipeline inspection was conducted. No blockage was found, and the drill rod was raised to the height of the fifth grouting hole.

[0106] When grouting is performed in the fifth grouting hole, according to the real-time monitoring data, the grouting flow rate remains below 12.5 L / min for 7 minutes, and the grouting pressure shows an upward trend reaching 0.92 MPa. When grout overflows from the hole, it is determined that the conditions for lifting the drill rod are met, and the rod lifting operation is performed. Since the fifth grouting hole is the last grouting hole, grouting is stopped at the same time when the rod is lifted, and the grouting operation is completed. At this time, the segmented grouting from bottom to top and the full hole filling are completed.

[0107] The implementation also shows that the setting of grouting points is determined according to the actual site conditions, and the number of grouting points does not affect the technical effect of the present invention.

[0108] Step 5: Slope adjustment and effect verification: After grouting, reduce the slope ratio from 1:1 to 1:1.5, remove loose material from the slope surface, and spray 10cm thick C25 concrete.

[0109] The engineering case adopted the integrated construction method of dewatering and grouting reinforcement for the tunnel entrance slope section in water-rich miscellaneous fill strata provided by this invention. The monitoring results showed that: (1) Settlement monitoring: During the 22-day monitoring period, the maximum settlement at the top of the slope was 11.13 mm, which was lower than the standard limit of 30 mm; (2) Safety factor: increased from 0.97 to 1.45. The method provided by this invention achieved excellent reinforcement effect.

[0110] Example 8

[0111] like Figure 1 , Figure 2 , Figure 3 As shown, an integrated construction control system for dewatering, drainage, and grouting is used to implement an integrated construction method for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata. The system includes: a drilling equipment 1; a main drill rod 2, comprising a casing 3, a core tube 4, and a position switching mechanism 5, wherein the casing 3 and the core tube 4 can rotate relative to each other via the position switching mechanism 5; a water extraction pipe 6 and a grouting pipe 7 are branched from the main drill rod 2, and a water extraction valve 8 and a water pump 9, and a grouting valve 10 and a grouting pump 11 are respectively installed on the water extraction pipe 6 and the grouting pipe 7 to control the water extraction volume and the grouting volume respectively; the core tube 4 has two external channels, a water extraction hole 12 and a grouting hole 13, with the water extraction hole 12 located on the core tube. 4. The grouting hole 13 is arranged at the bottom of the core tube 4 on the side wall; the sleeve 3 is provided with a water inlet 14 corresponding to the water inlet 12, and the front end 24 is provided with a slot 15 corresponding to the grouting hole 13. The sleeve 3 and the core tube 4 can rotate relative to each other through the position switching mechanism 5 to realize the angle cooperation between the sleeve 3 and the core tube 4, so as to open or close the water inlet 14 for water pumping, and to open or close the grouting hole 13 for grouting; the grouting pipe 7 is connected to the mixed slurry storage tank 16, and the mixed slurry storage tank 16 is connected to the cement slurry storage tank 17, the cement slurry delivery pump 18, the water glass storage tank 19, and the water glass delivery pump 20, so as to realize the real-time configuration of the mixed slurry.

[0112] The position switching mechanism 5 is a locking mechanism with an angular apex, used to limit the relative position between the sleeve 3 and the core tube 4. The upper end cap of this mechanism is installed on the end of the sleeve 3 by screws. This part is connected to the sleeve 3 and has no relative movement, while simultaneously limiting the axial movement of the core tube 4. The upper end cap of the position switching mechanism 5 has three threaded holes, distributed in a fan shape with the center of the sleeve 3. The core tube 4 has a protruding structure with a threaded hole. When the core tube 4 rotates, this hole will have three points on its circumferential trajectory that coincide with the three threaded holes on the upper end cap of the position switching mechanism 5. When they coincide, two of the threaded holes can be threaded onto the screw using a screw and nut, and locking the nut will complete the position change. The three holes correspond to the three working states.

[0113] like Figure 4As shown, the pumping holes are evenly arranged on the side wall of the core tube at 120° intervals, and the grouting holes are fan-shaped openings and evenly arranged at the bottom of the core tube at 120° intervals; the front end of the casing 4 has three slots corresponding to the grouting holes. The position switching mechanism 5 achieves three modes by rotation. When the core tube 4 rotates, the threaded holes on its extension mechanism will have three points on the circumferential trajectory that coincide with the three threaded holes on the upper end cover of the position switching mechanism 5. When they coincide, the two threaded holes can be put into the screws by screws and nuts, and the position can be changed by locking the nuts. The three holes correspond to the three working states: (1) Drilling mode: the grouting valve and the pumping valve are all closed, and the pumping port and the grouting port are both closed; (2) Pumping mode: the grouting valve is closed, the pumping valve is open, the pumping port is open and the grouting port is closed; (3) Grouting mode: the grouting valve is open, the pumping valve is closed, the grouting port is open and the pumping port is closed. In addition, it can also be switched to the well washing mode: the casing slots and the grouting holes are partially overlapped to achieve low-pressure water flushing. In other embodiments, the pumping holes are evenly spaced on the sidewalls of the core tube and the casing, and the grouting holes are evenly spaced at the bottom of the core tube. A slot corresponding to the grouting holes is provided at the front end of the casing. The angle and number of slots are not limited to this embodiment; all can achieve the technical effect of adjusting the relative rotation between the core tube and the casing through the rotation of the position switching mechanism 5, thereby opening and closing the pumping holes and grouting holes. A sealing ring is used between the casing and the core tube to seal them, allowing the tubes to withstand positive and negative pressure, which is beneficial for pumping, drainage, and grouting operations.

[0114] It also includes a monitoring device, which includes a flow meter 23a installed on the pumping pipeline, a flow meter 23d installed on the grouting pipeline, a flow meter 23b installed on the water glass conveying pipeline, a flow meter 23c installed on the cement slurry conveying pipeline, and a grouting pressure gauge 22 installed on the grouting pipeline, for real-time monitoring of pumping volume, grouting pressure, and grouting volume; a mixer 21 is also installed on the mixed slurry storage tank.

[0115] Example 9

[0116] This embodiment details the structure and operation of a combined construction control system for dewatering pumping and grouting:

[0117] The system consists of four parts: drill rod assembly, pipeline system, grout preparation unit and automatic control unit. The drill rod assembly structure is as follows: inner core tube: Φ76mm×6mm hot-rolled seamless steel pipe, 14m in length. Three rows of Φ15mm water extraction holes are opened at 120° intervals on the side wall; three 60° fan-shaped grouting holes are opened at the bottom; outer sleeve: Φ89mm×6mm steel pipe, 14.2m in length. Water extraction ports are opened on the side wall that coincide with the water extraction holes; three 60° slots are opened at the bottom; the position switching mechanism 5 adopts a gear transmission device, and the rotation angle corresponds to the following states: (1) Drilling mode: the grouting valve and the water extraction valve are all closed, and the water extraction port and the grouting port are both closed; (2) Water extraction mode: the grouting valve is closed, the water extraction valve is open, the water extraction port is open and the grouting port is closed; (3) Grouting mode: the grouting valve is open, the water extraction valve is closed, the grouting port is open and the water extraction port is closed. In addition, it can switch to well-washing mode: the casing groove and the grouting hole partially overlap to achieve low-pressure water flushing. The position switching mechanism can also be implemented using other methods in the prior art that allow the core tube and casing to rotate relative to each other and lock at a specific angle.

[0118] Dynamic control logic: The flow meter monitors the pumping rate in real time. When k>10m / d or L>120m 3 When the grouting pressure is 1m / d, it is determined to be a high-permeability formation, and the grouting pressure is increased by 20%-40% based on the design grouting pressure P1; the volume ratio of cement grout to water glass is adjusted to 1:1.0-1:1.5; when 1m / d≤k≤10m / d or 12m 3 / d≤L≤120m 3 When k < 1 m / d, the formation is classified as medium permeability, and the grouting pressure is maintained at the design grouting pressure P1 or ±10%; the volume ratio of cement grout to water glass is adjusted to 1:0.7-1:1.0; when k < 1 m / d or L < 12 m 3 When the grouting pressure is / d, it is determined to be a low-permeability formation. The grouting pressure is reduced by 15%-30% based on the design grouting pressure P1; the volume ratio of cement grout to water glass is adjusted to 1:0.4-1:0.7.

[0119] When this system is used to implement the integrated construction method of dewatering, drainage, and grouting reinforcement at the tunnel entrance slope in water-rich, miscellaneous fill strata, its working process is as follows:

[0120] System installation and drilling. For example... Figure 5As shown, the water-rich area was determined based on geophysical exploration results and the actual elevation of the landslide water inflow point. First, backfilling was carried out at the leading edge of the landslide to stabilize the slope. The combined dewatering, pumping, and grouting control system was installed at the outer edge of the slope crest elevation, at least 5 meters outside the landslide line, based on settlement control requirements. This system, together with the original intercepting ditch, constituted the slope dewatering and pumping system. After installation, the main drill rod switching mechanism was switched to drilling mode. At this time, both the grouting and pumping holes were closed, and the grouting and pumping valves were shut off. The drilling rig was then started to begin drilling operations, inserting the main drill rod to the designed depth.

[0121] Pumping operation. After the main drill pipe is inserted into position, switch the drill pipe switching mechanism to pumping mode. At this time, the grouting port is closed, the pumping hole is opened, the grouting valve is closed, the pumping valve is opened, and the pumping pump is started to begin pumping. During the pumping process, the k value obtained from the on-site survey and the flow rate of a single hole are monitored in real time by the flow meter. The change curve of the pumping rate over time is recorded to determine the formation permeability, the thickness of the water-rich layer, and the drainage effect. When 1m / d ≤ k ≤ 10m / d or 12m 3 / d≤L≤120m 3 When the grouting pressure is / d, it is determined to be a medium-permeability formation. The grouting pressure is maintained at the design value, or slightly adjusted within ±10% above or below it. The volume ratio of cement grout to water glass is adjusted to 1:0.7-1:1.0 to achieve the grout balance diffusion and consolidation requirements.

[0122] In this embodiment, the initial pumping volume is 50m³. 3 / h indicates that the formation has moderate permeability and contains fine particles. When the precipitation gradually decreases and tends to stabilize (the pumping rate changes by less than 5% for 1 consecutive hour), the precipitation pumping operation is terminated. This step lasts approximately 3 days and 6 hours.

[0123] Dynamic configuration of grouting materials. After the pumping operation is completed, the pumping valve should be closed promptly. Based on the formation conditions (medium permeability) reflected by the change in pumping volume in step 3, the mixing ratio of cement grout and water glass should be dynamically adjusted to 1:0.8 to achieve rapid setting and effective filling. The cement grout and water glass should be pumped to a mixer for mixing and preparation, and the prepared two-component mixture should be stored in a storage tank for later use.

[0124] Grouting operation. After the two-component mix ratio is prepared, close the pumping valve and open the grouting valve. Switch the main drill pipe switching mechanism to grouting mode, close the pumping port and open the grouting port to begin grouting. There are 10 grouting points from bottom to top. Figure 6aAs shown in Figures 6b and 6c: First, grout is injected to fill the area below the water inflow line. The grouting pressure gauge and flow meter of this system are used to closely observe changes in these parameters for dynamic control. When the conditions for lifting the drill rod are met, the drill rod is raised to the next grouting point. This process continues until the last grouting point meets the lifting conditions, at which point the drill rod is finally pulled out, ending the grouting operation. During this process, the soil layer is uniformly grouted throughout the entire vertical depth.

[0125] It should be noted that: 1. The technical solution and specific implementation of this invention are described in the context of a landslide caused by water inrush at the tunnel entrance slope in a water-rich, mixed-fill soil stratum after heavy rainfall. However, the application of this invention is not limited to the tunnel industry described; it is compatible with slope diseases under similar geological conditions and rainfall conditions. 2. The drilling equipment listed in this invention is not limited in type or form; manual or other methods are also compatible. 3. The grouting method of this solution is not limited to two-liquid mixed grouting; single-liquid grouting or multi-liquid mixed grouting are also acceptable. Existing technologies that meet the requirements of short setting time and high compressive strength of grouting materials can be applied.

Claims

1. A method for integrated dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata, characterized in that, Includes the following steps: Step 1: Determine the location, number, and grouting parameters of the integrated pumping and grouting operation holes based on the slope precipitation parameters and slope perimeter; Step 2: Stabilize the slope by backfilling with soil at the leading edge of the landslide. Drill holes for integrated pumping and grouting operations at the outer edge of the slope top elevation above the landslide line. Step 3: After drilling to the required depth, switch to pumping mode to pump water, monitor the water output L of a single borehole in real time, and obtain the formation permeability coefficient k based on the on-site survey; judge the formation permeability based on the formation permeability coefficient k and the monitored water output L of a single borehole, and dynamically adjust the grouting pressure and grout mix ratio accordingly. Step 4: After the drainage is terminated, switch to grouting mode to carry out grouting operations. Divide the area below the water inflow line into several grouting points from bottom to top. Starting from the first grouting point, monitor the changes in flow rate and grouting pressure in real time, and dynamically control the termination of grouting and the lifting of the drill rod. When the lifting conditions are met, lift the drill rod to the next grouting point until the segmented grouting from bottom to top is completed.

2. The integrated construction method for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata according to claim 1, characterized in that: The method for determining the layout of the integrated extraction and grouting operation holes is as follows: using an equidistant hole layout in a quincunx pattern.

3. The integrated construction method for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata according to claim 2, characterized in that: The method for determining the number n of integrated extraction and grouting operation holes is as follows: Q is the total inflow of water from the foundation pit (m³). 3 / d), the calculation method is: Where H1 is the thickness of the unconfined aquifer, and S d The design drawdown depth for the groundwater level in the foundation pit, where R is the radius of influence of the drawdown, is calculated as follows: ; The equivalent radius of the precipitation range is calculated as follows: A is the area of ​​the foundation pit; q is the water output per single hole (m³). 3 / d), the calculation method is: ; r is the radius of the integrated pumping and grouting operation hole, l is the effective length of the water inlet section of the integrated pumping and grouting operation hole; k is the weighted average of the permeability coefficient of each soil layer according to the soil layer thickness, calculated as follows: , where k j H represents the permeability coefficient of each soil layer. j H represents the average thickness of each soil layer; H represents the average total thickness of the overlying soil layer.

4. The integrated construction method for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata according to claim 2 or 3, characterized in that: The method for determining grouting parameters described in step 1 is as follows: Overburden pressure , Where ρ is the natural density of the overburden, g is the acceleration due to gravity, h is the thickness of the fill layer, grouting pressure P2 = 2 × overburden pressure P, design grouting pressure P1 = grouting pressure P2 - initial grouting loss pressure ΔP; Q1 is the design grouting volume per hole (m³). 3 ), , The grout filling coefficient is... denoted as grout loss coefficient; r1 as effective diffusion radius of grout; l as effective length of water inlet of the integrated pumping and grouting operation hole; n as soil porosity; the ratio of cement grout and water glass mixed grout used for grouting meets the requirements of initial setting time ≤ 60s and 28-day compressive strength ≥ 10MPa.

5. The integrated construction method for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata according to claim 4, characterized in that: The method in step 3 for determining formation permeability based on the formation permeability coefficient k and the monitored single-well water output L, and then dynamically adjusting the grouting pressure and grout mix ratio accordingly, is as follows: When k>10m / d or L>120m 3 When the grouting pressure is / d, it is determined to be a high-permeability formation, and the grouting pressure is increased by 20%-40% based on the design grouting pressure P1; the volume ratio of cement grout to water glass is adjusted to 1:1.0-1:1.

5. When 1m / d≤k≤10m / d or 12m 3 / d≤L≤120m 3 When the grouting pressure is / d, it is determined to be a medium-permeability formation. The grouting pressure is maintained at the design grouting pressure P1 or ±10%; the volume ratio of cement grout to water glass is adjusted to 1:0.7-1:1.

0. When k < 1m / d or L < 12m 3 When the grouting pressure is / d, it is determined to be a low-permeability formation. The grouting pressure is reduced by 15%-30% based on the design grouting pressure P1; the volume ratio of cement grout to water glass is adjusted to 1:0.4-1:0.

7.

6. The integrated construction method for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata according to claim 5, characterized in that: The method for dynamically controlling the grouting termination and drill pipe lifting in step 4 is as follows: The initial grouting flow rate is set to 15–25 L / min. When the grouting pressure reaches the dynamically adjusted grouting pressure and is stabilized for 3 to 5 minutes, the grouting flow rate drops to 7–8 L / min and remains stable for at least 5 to 10 minutes. If the conditions for lifting the drill rod are met, the rod lifting operation is carried out. When the grouting pressure increases and the rate of pressure increase is greater than 0.1 MPa / min, and the grouting flow rate has dropped to less than 50% of the initial grouting flow rate, it is determined that there is a risk of pipe blockage. Pipeline inspection is carried out. If there is no blockage, the rod lifting operation is performed. When the grouting pressure is lower than 50% of the dynamically adjusted grouting pressure for 3 to 5 minutes and the grouting flow rate increases to 26-28 L / min, grouting is paused and the drill rod is not lifted. The volume ratio of cement slurry to water glass is adjusted to increase the volume percentage of water glass in the mixed slurry by 10-30% to accelerate soil solidification. Then, grouting is resumed and the flow rate is reduced to 7-8 L / min. At the same time, the actual grouting pressure is monitored to see if it returns to the dynamically adjusted grouting pressure. Once the pressure returns to the dynamically adjusted grouting pressure and is stabilized for 3 to 5 minutes, the conditions for lifting the drill rod are met, and the rod lifting operation is performed. When the grouting flow rate is lower than 50% of the initial flow rate for 5-8 minutes and the grouting pressure shows an upward trend, and grout appears to be seeping out of the borehole, it is determined that the conditions for lifting the drill rod are met, and the rod lifting operation is performed.

7. The integrated construction method for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata according to claim 1, characterized in that: It also includes step 5: after grouting is completed, the slope of the slope is reduced, local unstable fill is removed, and the overall stability of the slope is enhanced.

8. A combined construction control system for dewatering, drainage, and grouting reinforcement of the tunnel entrance slope section in water-rich miscellaneous fill strata as described in claims 1-7, characterized in that: The system includes: a drilling equipment (1); a main drill rod (2), comprising a casing (3), a core tube (4), and a position switching mechanism (5), wherein the casing (3) and the core tube (4) can rotate relative to each other via the position switching mechanism (5); a water pumping pipe (6) and a grouting pipe (7) are branched off from the main drill rod (2), and a water pumping valve (8), a water pumping pump (9), a grouting valve (10), and a grouting pump (11) are respectively installed on the water pumping pipe (6) and the grouting pipe (7) to control the water pumping volume and the grouting volume respectively; the core tube (4) is provided with two external channels, a water pumping hole (12) and a grouting hole (13), the water pumping hole (12) being arranged on the side wall of the core tube (4), and the grouting hole (13) being arranged at the bottom of the core tube (4); the casing (3) is provided with a... The pumping hole (12) corresponds to the pumping port (14). The front end of the sleeve (24) is provided with a slot (15) corresponding to the grouting hole (13). The sleeve (3) and the core tube (4) can rotate relative to each other through the position switching mechanism (5) to achieve the angle matching between the sleeve (3) and the core tube (4), so as to open or close the pumping hole (12) and the pumping port (14) for pumping water, and to open or close the grouting hole (13) for grouting. The grouting pipe (7) is connected to the mixed slurry storage tank (16). The mixed slurry storage tank (16) is connected to the cement slurry storage tank (17), the cement slurry delivery pump (18), the water glass storage tank (19), and the water glass delivery pump (20), so as to realize the real-time configuration of the mixed slurry.

9. The integrated construction control system for dewatering pumping and grouting as described in claim 8, characterized in that: The water extraction holes (12) are evenly arranged at 120° intervals on the side wall of the core tube (4), the water extraction ports (14) are evenly arranged at 120° intervals on the side wall of the sleeve (3), the grouting holes (13) are fan-shaped openings and are evenly arranged at 120° intervals on the bottom of the core tube (4); the front end of the sleeve (3) is provided with three slots (15) corresponding to the grouting holes (13).

10. The integrated construction control system for dewatering pumping and grouting according to claim 9, characterized in that: The sleeve (3) and the core tube (4) are sealed with a sealing ring, so that the tubes can withstand positive and negative pressure, which is beneficial to pumping and grouting operations; it also includes a monitoring device, which includes a flow meter 1 (23a) installed on the pumping pipeline, a flow meter 2 (23d) installed on the grouting pipeline, a flow meter 3 (23b) installed on the water glass conveying pipeline, a flow meter 4 (23c) installed on the cement slurry conveying pipeline, and a grouting pressure gauge (22) installed on the grouting pipeline, for real-time monitoring of pumping volume, grouting pressure and grouting volume; a stirrer (21) is also installed on the mixed slurry storage tank.

Images