A construction method for cast-in-place drilling using a double slurry mixer

Abstract

The application discloses a construction method for drilling perfusion by using a double-liquid slurry mixer, and comprises the following steps: step ST100, tool positioning; step ST200, geological surveying and determining double-slurry mixing ratio; step ST300, system interfacing; the double-liquid slurry mixer is communicated with a drill rod, a sodium silicate slurry pipe and a water pressure plug pipe respectively, and is lowered to a depth of 1-2 meters above a first discovered water gushing or loss layer; step ST400, hole sealing; step ST500, double-slurry injection; and step ST600, system closing and tool taking out. The double-slurry perfusion construction method can adapt to various geological drilling processes, and effectively seals water gushing or loss at various stratum depths. When a hole with a large preset depth is constructed, the method can seal water gushing layers or loss layers at different depths, and is not affected by the depth and the water gushing degree.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of geological grouting, in particular to the technical field of plugging and grouting of water gushing and leakage in the process of grouting drilling, and specifically relates to a construction method for drilling and grouting by using a double slurry mixer. BACKGROUND

[0002] Double slurry plugging is mainly applied to large leakage or large water gushing conditions to plug the leakage or water gushing at a specific depth. Double slurry plugging construction is not equivalent to geological grouting. Before geological grouting construction is performed on the target area, drilling is needed to provide a channel for slurry to enter during subsequent grouting operations. During drilling, water gushing and hole collapse may occur due to different geological environments, especially water gushing during drilling, which greatly hinders the drilling operation. At this time, double slurry plugging can be used to solve the problems of water gushing or leakage, so that drilling work can continue. If the water gushing problem is not effectively controlled and solved, it is almost impossible to reach the preset drilling depth, and even underground hole collapse may occur. In order to avoid the problem of being unable to continue drilling due to water gushing during drilling, mud and weighted mud are often used in combination with drilling construction in the prior art to balance the underground pressure, and mud can form a protective wall during drilling to prevent the expansion of water gushing and hole collapse. However, when serious water gushing occurs, conventional mud cannot achieve plugging, and water glass slurry and cement slurry need to be used together to plug water gushing underground to avoid hole collapse and enable drilling to continue to the specified depth.

[0003] However, in order to achieve plugging under the condition of large water gushing, water glass slurry and cement slurry need to be sent to the specified depth according to the specified ratio to effectively plug the water gushing, which requires a specific construction process or method. There are many construction grouting methods for double slurry plugging in the prior art, such as the invention patent application with publication number CN106639973A, which discloses a grouting structure and a grouting method for double slurry grouting of an ultra-deep hole on the ground. It provides a double slurry grouting structure. The basic principle adopted is to independently send cement slurry and water glass slurry to the hole at the specified depth, and then use a stopper to define a section of the hole as a mixing chamber to send the independent cement slurry and water glass slurry into the mixing chamber to achieve mixing. The above prior art can reach a larger depth in the hole, but its disadvantages are also very obvious, mainly including: first, mixing in the hole, as the hole has various slurry impurities, the water glass slurry and cement slurry sent by hand cannot be mixed according to the preset ratio. Second, natural mixing in the hole space does not guarantee the uniformity control mechanism of double slurry mixing, which can easily cause uneven mixing and lose the advantages of double slurry plugging. SUMMARY

[0004] In order to solve the problems existing in the prior art, the application provides a construction method for drilling and grouting by using a double-liquid slurry mixer to overcome the disadvantages of the prior art, achieve precise slurry control and slurry delivery, implement targeted and precise rapid plugging for water gushing or loss layers, and solve the problems of discrete loss and / or water gushing in particularly difficult and complex strata drilling.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0006] A construction method for drilling and grouting by using a double-liquid slurry mixer, comprising the following steps:

[0007] Step ST100: tool positioning; assemble the double-liquid slurry mixer including the mixer body and the water pressure plug, and wait for use;

[0008] Step ST200: determining the mixing ratio of the double slurry according to the geological survey; perform hole scanning, fracture flushing and water pressure test on the target hole, and determine the mixing ratio of the cement slurry and the water glass according to the water pressure test;

[0009] Step ST300: system interfacing; connect the double-liquid slurry mixer with the drill pipe, the water glass slurry pipe and the water pressure plug pipe respectively, and lower the hole to 1-2 meters above the first discovered water gushing or loss;

[0010] Step ST400: hole sealing; inject water into the water pressure plug pipe to pressurize, so that the water pressure plug expands until a stable clamping structure is formed between the water pressure plug and the hole wall, and the entire hole space is divided into an upper open cavity and a lower closed cavity;

[0011] Step ST500: double slurry injection; simultaneously inject the cement slurry of the preset concentration into the drill pipe and the water glass slurry into the water glass slurry pipe, and the injection amount and the grouting pressure are executed according to the preset scheme until the grouting is completed;

[0012] Step ST600: close the system and take out the tool; close the cement slurry pipeline, the water glass slurry pipeline and the water pressure plug pipeline in sequence, take out and clean the double-liquid slurry mixer, and complete the current drilling and grouting; when the hole wall loss and water gushing are plugged, continue to scan and drill, and repeat steps ST100-ST600 when a second water gushing or loss point is found.

[0013] In order to ensure that the construction method provided by the application can directly obtain the expected technical effect, the double-liquid slurry mixer which plays a key role in the entire construction method is optimized and set in a series of ways, specifically, the following multiple optimization structure design schemes are adopted: the double-liquid slurry mixer is composed of a mixer body for mixing cement slurry and water glass, and a water pressure plug for fixing the mixer body at a specified depth in the hole and detachably connecting the mixer body below.

[0014] Preferably, the mixer body comprises an outer shell, a reverse valve fixedly arranged in the outer shell for dividing the inner cavity of the outer shell into independent and sealed first and second channels, the reverse valve having a valve core for unidirectional conduction of the first channel, the first and second channels being communicated at the ends thereof through a mixing chamber provided at the tail of the outer shell, the mixing chamber having an expanded structure and an axial section gradually converging along the fluid flow direction; the inlet end of the first channel is connected with a cement slurry inlet pipe, and the outlet end near the mixing chamber is provided with a converging axial section along the fluid flow direction; the inlet end of the second channel is connected with a water glass slurry inlet pipe, and the outlet end is provided with a wire drawing nozzle, and the mixing chamber is connected with a mixed slurry outlet pipe. Regarding the cement slurry conveying principle in the first channel, the cement slurry is pressurized by the slurry conveying pump and then reaches the valve core position from the cement slurry inlet pipe and the reverse valve in sequence. Since the valve core has the function of blocking the cement slurry from entering, when the pressure of the cement slurry conveyed by the slurry conveying pump is greater than the pressure of the valve core, the cement slurry enters the mixing chamber after overcoming the resistance of the valve core. At the same time, the water glass is conveyed by the slurry conveying pump to the water glass slurry inlet pipe, thereby entering the second channel, and finally the water glass is sent into the mixing chamber in a predetermined form through the wire drawing nozzle to mix with the cement slurry in the first channel. The wire drawing nozzle has the function of preventing backflow, avoiding the problem of water glass pipeline blockage caused by the backflow of cement slurry into the wire drawing nozzle after stopping pressurization. Since the mixing chamber has an expanded structure, it can reduce the flow rate of the cement slurry after entering the expanded structure and fully mix with the water glass slurry after wire drawing. In addition, the mixing chamber is provided in a converging structure along the fluid flow direction, which further extrudes the mixed slurry and changes the mixing uniformity of the mixed slurry, further improving the mixing uniformity of the slurry. After the double slurry is fully mixed in the mixing chamber, it enters the pre-set depth section of the hole through the mixed slurry outlet pipe to form a seal for the wall of the gushing hole section.

[0015] It is worth noting that the mixing ratio of the double slurry is not related to the mixer provided in the present application, and the preset ratio is determined by the conveying flow of the conveying pump for providing cement slurry and water glass slurry respectively. Regarding the conveying depth, the cement slurry inlet pipe of the mixer provided in the present application is communicated with the slurry conveying pipeline of the drill pipe, which can mix the double slurry to the specified depth according to the actual construction requirements, and is not limited to the shallow layer of mixed slurry. In order to improve the stability, the mixer can also be fixed with the existing water pressure plug pipe, which can better play the effect of precise sealing.

[0016] Further preferably, the first channel is composed of a cement slurry inlet pipe, a valve core and a jet pipe connected to the mixing chamber in sequence, the valve core comprises a high-pressure spring and a steel ball in abutting contact with the high-pressure spring for preventing backflow of the cement slurry, the jet pipe is gradually convergent inside along the flow direction of the cement slurry, and the critical section where the jet pipe intersects with the mixing chamber is the minimum cross section; the side wall of the jet pipe is provided with a plurality of through holes for absorbing water glass slurry. The purpose of using a spherical steel ball as the valve core component is to provide reliable sealing and prevent backflow in the cement slurry containing particulate impurities. The steel ball sealing is a linear sealing, which can naturally avoid particulate matters in the cement slurry, and has better practicability and adaptability to the environment compared with a face sealing one-way valve. The purpose of setting the jet pipe with a convergent internal channel is to enable the cement slurry to accelerate when flowing in the jet pipe. The cross section through which the cement slurry exits the jet pipe at the moment is the smallest, and the flow rate of the cement slurry is the fastest at this time. When entering the mixing chamber at the maximum speed, a local negative pressure is formed, which instantly sucks in the water glass slurry on the side to form a local cyclone. This internal cyclone is similar to the Venturi effect, which can positively promote the mixing of the water glass slurry and the cement slurry. After the cyclone, the mixing chamber is enlarged compared with the jet pipe, which can quickly reduce the speed and form a limited turbulent flow in the mixing chamber. In combination with the convergent mixing chamber at the tail section, the slurry mixing is further made more uniform. The second channel is connected to the side wall of the jet pipe through the plurality of through holes, which realizes the first premixing of the cement slurry and the water glass slurry. Since the jet pipe is convergent, the overall flow rate of the cement slurry flowing in the jet pipe is equal. Since the cross-sectional area is constantly decreasing, the flow rate of the cement slurry is constantly increasing. Based on the Venturi principle, the water glass in the second channel will be sucked into the jet pipe under the negative pressure formed by the high-speed flowing cement slurry, realizing a small amount of double slurry mixing. Since the uniformity of double slurry mixing will directly affect the plugging effect, setting time and stability of the lost circulation zone and gushing layer, the more uniform the slurry, the closer the plugging setting time and the stability to the expected theoretical value, the more uniform the double slurry mixing is, which is the technical effect that any mixer pursues, and the present application is no exception.

[0017] In summary, the above structure can realize two-stage mixing, i.e. the primary mixing of the water glass absorbed through the through holes on the jet pipe and the secondary mixing of the double slurry in the mixing chamber, to ensure the uniformity of the double slurry mixing. It is worth noting that the convergent structure inside the jet pipe is necessary. If an expanding pipe or a straight pipe is used, the structure with the through holes cannot achieve the expected mixing effect and the Venturi effect cannot occur.

[0018] Further preferably, the outer shell comprises a first shell segment and a second shell segment, the first shell segment and the second shell segment are connected by a detachable fixed connection of a connecting sleeve, the connecting sleeve has a plurality of through holes that communicate with the first shell segment and the second shell segment, any of the through holes is provided with the wire drawing nozzle near one end of the mixing chamber; the second channel is composed of an annular space formed between the inner wall of the first shell segment and the outer lateral wall of the first channel and a plurality of through holes; the first channel and the second channel meet in the mixing chamber provided in the second shell segment; the second shell segment is provided with a plurality of groups of spiral guides alternately on the pipe wall downstream of the mixing chamber in the fluid flow direction, the guide directions of adjacent two groups of spiral guides are opposite; any group of the spiral guides is composed of at least three spiral blades that are located at the same axial position and are uniformly distributed on the inner wall of the second shell segment. After the double slurry is mixed in the mixing chamber, when flowing through the downstream pipe wall, due to the contact with the spiral guide, under the guiding action of the spiral guide, the mixed double slurry will flow along the guide; however, because the spiral guide is provided with a plurality of groups, and the guide directions of adjacent two groups are opposite, that is, the guide direction of the previous group of spiral guides is clockwise, and the guide direction of the next group of spiral guides is counterclockwise, and so on. Then the mixed slurry flows repeatedly in the circulation action of forward flow → turbulence → reverse flow → turbulence → forward flow, and after multiple circulations, the mixed slurry will be mixed more uniformly. The guide directions of any spiral blade of the same group are the same, and each spiral blade is fixedly provided on the pipe wall. There is no any movable component, the structure is compact, simple and highly reliable.

[0019] In order to reliably fix the mixer, preferably, the water pressure plug is provided with a mixing slurry inlet pipe that is detachably fixedly connected to the mixing slurry outlet pipe through a wire connector; a pair of fixed connectors that are fixedly and oppositely arranged on the circumferential side wall of the mixing slurry inlet pipe, a rubber pipe that connects the two fixed connectors, and a water pressure plug pipe arranged on any of the fixed connectors for communicating the space between the inner wall of the rubber pipe and the outer wall of the mixing slurry inlet pipe.

[0020] In order to improve the adaptability and compatibility of the water pressure plug to different geological environments, preferably, the fixed connector that is not provided with the water pressure plug pipe is replaced with a movable connector that fixedly connects the rubber pipe, the movable connector is in sliding sealing connection with the outer lateral wall of the mixing slurry inlet pipe; the inner lateral wall of the movable connector is provided with a plurality of sealing rings that are in close contact with the mixing slurry inlet pipe.

[0021] In order to improve the better plugging effect of the mixed double slurry on the hole wall after injection, the mixing ratio of the cement slurry and the water glass is 17:0.9-1.1.

[0022] Beneficial effects

[0023] The double slurry perfusion construction method can adapt to various geological drilling processes and effectively block water gushing or leakage at various stratum depths.

[0024] The double liquid slurry mixer can fix the mixer at a specified depth position, so that the specificity and accuracy of the double slurry water gushing blocking are higher. The mixer mixes the cement slurry and the water glass slurry near the target area, which can solve the problems of pipe blocking caused by premature solidification and uneven mixing of the double slurry in the hole, and solve the industry pain points and technical difficulties in the double slurry perfusion blocking technology. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0026] Figure 1 is a process schematic diagram of the present application;

[0027] Figure 2 is a three-dimensional structure schematic diagram of the double liquid slurry mixer;

[0028] Figure 3 is Figure 2 the axial sectional view of the mixer in the embodiment;

[0029] Figure 4 is Figure 3 the enlarged view of the A area structure in the embodiment (slurry mixing schematic diagram of Venturi principle);

[0030] Figure 5 is Figure 3 the enlarged view of the A area structure in the embodiment (another embodiment structure);

[0031] Figure 6 is Figure 3 the enlarged view of the B area structure in the embodiment;

[0032] Figure 7 is Figure 2 the axial sectional view of the water pressure plug in the embodiment;

[0033] Figure 8 is a structure schematic diagram of the water pressure plug in the fixed state;

[0034] Figure 9 is a hole structure schematic diagram after being separated by the water pressure plug;

[0035] Figure 10 Structure diagram for example 4;

[0036] Figure 11 For Figure 10 Structure enlargement of C area.

[0037] In the figure: 1-outer shell; 2-water pressure plug; 3-cement slurry inlet pipe; 4-sodium silicate slurry inlet pipe; 5-water pressure plug pipe; 6-reverse valve; 7-steel ball; 8-high pressure spring; 9-connection sleeve; 10-through hole; 11-wire drawing nozzle; 12-mixing cavity; 13-wire connecting connector; 14-mixed slurry inlet pipe; 15-fixed joint; 16-rubber pipe; 17-sealing ring; 18-movable joint; 19-open upper cavity; 20-closed lower cavity; 21-slit; 22-ball check valve. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts are within the scope of protection of the present application.

[0040] In order to better illustrate the construction method claimed in the present application, and the dual-liquid slurry mixer which plays a major role in the method, the following will be elaborated in the form of actual cases.

[0041] Example 1:

[0042] This embodiment is illustrated in combination with the actual construction case of Luding Hydropower Station, aiming to clearly and thoroughly express the construction method described in the present application and the technical effects achieved.

[0043] Luding Hydropower Station is located in Luding County, Sichuan Province, and is the 12th cascade hydropower station on the main stream of Dadu River. The normal storage level of the reservoir is 1378.00 m, the total storage capacity is 219.5 million m3, the installed capacity is 920 MW, and the project is a large-sized project. The dam of the power station is a clay core rockfill dam built on the overburden layer, with a crest elevation of 1385.50 m and a maximum height of 79.50 m. The overburden layer at the dam site is deep, with a general thickness of 120-130 m and a maximum thickness of 148.6 m. The riverbed part is 0+105.50 m-0+250.30 m, and the dam foundation anti-seepage system is composed of three rows of grouting curtains connected with the vertical concrete anti-seepage wall, with a thickness of 1 m and a maximum depth of 110 m. The overburden grouting curtain has a depth of about 40 m. The dam foundation anti-seepage system on both sides is composed of vertical concrete anti-seepage wall and bedrock curtain grouting.

[0044] On March 31, 2013, seepage was found about 186 m downstream of the right-bank measuring weir, with coordinates X=3313814.9, Y=521975.9 and an elevation of about 1306 m, located 448 m downstream of the dam axis and about 209 m from the dam toe. The initial flow rate was about 5 L / s, and by April 15, 2013, ground collapse occurred in the seepage area, with a flow rate of about 200 L / s and a large amount of gray-black fine particles. The flow rate was later between 188 L / s and 212 L / s. Ground cracking and riverbed collapse occurred near the seepage point.

[0045] According to the exploration, the engineering geological conditions are as follows:

[0046] The overburden layer at the dam site is deep and complex, with a general thickness of 120-130 m and a maximum thickness of 148.6 m. According to the material composition, distribution, origin and formation age, it can be divided into the following four layers and seven sub-layers from bottom to top:

[0047] The first layer is a drift (block) ovate (crushed) gravel layer, which is an ice-water deposit, with a thickness of 51.85-75.31 m and a top plate buried depth of 62.2-81.8 m. The particle composition is mainly weakly weathered granite and diorite, with strong to moderate permeability.

[0048] The 2-1 sub-layer is a drift (block) ovate (crushed) gravel layer, with a thickness of 26.25-28.06 m and a top plate buried depth of 46.2-56.8 m, with strong to moderate permeability.

[0049] The 2-2 sub-layer is a crushed (ovate) gravel soil layer, with a thickness of 8.2-79.45 m and a top plate buried depth of 1.85-68.2 m. The particle composition is diorite and granite, mainly sub-angular, with strong to moderate permeability.

[0050] Sublayer ②-3: Silty fine sand and silt layer, lens-shaped, distributed in the middle and lower part of the river valley at the upper dam site, 6.52-32.8m thick, with a top plate buried at a depth of 29.68-39.36m. It is mainly composed of silt and fine sand, with a silt layer at the bottom, and has strong to medium permeability.

[0051] Sublayer ③-1: This layer contains loose (blocky) and pebbly (crushed) gravel. It is distributed on the first terrace of the dam site and on the right bank of the river valley at the upper dam site. It is 5.0-39.36m thick, with a top plate depth of 0-39.36m. The coarse-grained soil is primarily composed of weakly weathered granite and diorite, and is highly to weakly permeable.

[0052] The lens body of the ③-1b layer is medium-coarse sand containing muddy gravel, distributed in a lens shape, and is a weakly permeable soil.

[0053] ③-2 sublayer: gravel sand layer, about 8.3m thick, mainly composed of medium and coarse sand, with medium permeability.

[0054] Layer 4: Alluvial deposits of drifting gravel, distributed in the modern riverbed and floodplain of the dam site, with a thickness of 5.6-25.5m. Its particles are mainly composed of weakly weathered diorite and granite, and are highly permeable.

[0055] Because the ground is partially sandy, hole collapse is common during drilling, significantly impacting construction progress. Managing hole collapse is both a challenge and a key issue. To address these technical challenges, the applicant, through repeated research, invented a novel dual-liquid slurry mixer and utilized it for dual-slurry injection, addressing the aforementioned technical challenges of water gushing, hole collapse, and water loss.

[0056] like Figure 1 A construction method for drilling and grouting using a double slurry mixer is shown, comprising the following steps:

[0057] Step ST100: Put the tools in place; assemble the double slurry mixer including the mixer body and the hydraulic plug 2 and set aside for use; see Figure 2 The structure shown.

[0058] Step ST200: Conduct geological survey to determine the mixing ratio of the two slurries; perform hole sweeping, fissure flushing, and water pressure testing on the target hole, and determine the mixing ratio of cement slurry and water glass based on the water pressure test results; the specific hole sweeping construction sequence is as follows:

[0059] 1. First, use a φ60 composite sheet to make a hole;

[0060] 2. Use φ75 composite sheet to expand the hole;

[0061] 3. Use φ91 composite sheet to expand the hole;

[0062] 4. Use a short drill with a diameter of 91 mm and a length of 1 m to repair the hole;

[0063] 5 Adopt φ91 long 2m long drilling tool repair hole, ensure that the sleeve valve pipe can be smoothly set.

[0064] Step ST300 system interface; the double liquid slurry mixer is respectively communicated with the drill pipe, the water glass slurry pipe and the water pressure plug pipe, and the hole is lowered to 1-2 meters above the first discovered water gushing or loss; in the embodiment, the distance between the double liquid slurry mixer and the loss / water gushing point is controlled to be 1 meter ± 0.2 meters. It should be noted that the distance between the water gushing point and the lower end of the double liquid slurry mixer should be as small as possible, but cannot be negative, otherwise the water gushing point will be blocked and the double slurry plugging cannot be realized; the maximum is not more than 2 meters, when the distance is larger, the capacity of the double slurry contained in the hole is more, not only the slurry is wasted, but also the slurry is easy to solidify in the hole and cannot continue to be grouted, so that the hole wall plugging effect is poor, and even good plugging cannot be realized. Moreover, too much residual slurry in the hole will significantly increase the difficulty of subsequent hole sweeping, and reduce the total amount of double slurry penetrating into the hole wall. When loss or water gushing is found during drilling, drilling should be stopped immediately and the step is started.

[0065] Step ST400 hole sealing; water is injected into the water pressure plug pipe to pressurize, so that the water pressure plug 2 expands until a stable clamping structure is formed between the water pressure plug 2 and the hole wall, and the entire hole space is divided into an upper open cavity 19 and a lower closed cavity 20, as shown in Figure 9 ;

[0066] Step ST500 double slurry injection; cement slurry of a predetermined concentration is injected into the drill pipe and water glass slurry is injected into the water glass slurry pipe at the same time, the injection amount and grouting pressure are executed according to the preset scheme until the grouting is completed.

[0067] Step ST600 system closing and tool taking out; the cement slurry pipeline, the water glass slurry pipeline and the water pressure plug pipeline are closed in sequence, the double liquid slurry mixer is taken out and cleaned, and the current drilling grouting is completed; after the hole wall loss and water gushing are plugged, continue to sweep and drill, and repeat steps ST100-ST600 when secondary water gushing or loss point is found. Therefore, no matter what kind of complex formation and what degree of water gushing and loss, the hole wall can be plugged according to the above construction method, and after plugging, secondary hole sweeping is carried out. If the hole sweeping resistance is small, stop for 5 minutes and then sweep, until the hole sweeping resistance or the hole sweeping drilling speed is normal. It should be noted that the hole sweeping should not be carried out after dry condensation for a long time, so as to avoid excessive dry condensation of the double slurry mixed slurry at the bottom of the hole, increase the difficulty of secondary hole sweeping, and make the hole wall plugging effect not good.

[0068] In the above, it should be noted that the cement slurry pipe interface refers to airtight and reliable connection of the cement slurry pipe for flowing cement slurry. The cement slurry pipe refers to the pipeline through which the cement slurry flows alone, and not a specific structural part, but does not include the pipeline through which the double liquid slurry flows after mixing.

[0069] Water glass slurry pipe butt joint refers to airtight and reliable connection for water glass slurry pipeline for circulating water glass slurry, and the water glass slurry pipeline specifically refers to a pipeline through which the entire water glass slurry flows alone, and does not specifically refer to a certain structural part, but does not include a pipeline through which a double-liquid slurry flows after mixing.

[0070] Water pressure plug pipeline butt joint refers to airtight and reliable connection for water pressure plug pipeline for circulating clear water, and the water pressure plug pipeline specifically refers to a pipeline through which the entire clear water flows alone, and does not specifically refer to a certain structural part, and does not include any other pipeline.

[0071] In the step ST200 of the embodiment, the pressure parameters collected in the water pressure test are used to better select the specific gravity of the cement slurry and the mixing ratio between the cement slurry and the water glass slurry. Through repeated tests by the applicant, the mixing ratio of the cement slurry and the water glass is controlled to be between 17:0.9-17:1.1. Of course, as a person skilled in the art can conclude from the above content, if the water gushing in the actual application scene is more suitable for using the weighted fiber mud slurry with the water glass slurry, it is also understood that the technical content disclosed in the present application is the same.

[0072] Embodiment 2:

[0073] In order to better illustrate the originality of the present application and the principle and effect of the double-liquid slurry mixer for realizing precise plugging, the double-liquid slurry mixer is further described and illustrated based on the construction steps of Embodiment 1.

[0074] First, the double-liquid slurry mixer provided in the embodiment has the following structure:

[0075] As shown in the specific structure, Figures 2-7 The double-liquid slurry mixer includes an outer shell 1, a reverse valve 6 fixedly arranged in the outer shell 1 for dividing the inner cavity of the outer shell 1 into independent and airtight first and second channels, the reverse valve 6 having a valve core for unidirectional conduction of the first channel, the first and second channels being connected through a mixing chamber 12 arranged at the tail of the outer shell 1, the mixing chamber 12 having an enlarged structure and an axial cross section gradually converging along the fluid flow direction;

[0076] The inlet end of the first channel is connected with a cement slurry inlet pipe 3, and the outlet end is arranged in a converging manner along the axial section of the fluid flow direction near the mixing cavity 12; the inlet end of the second channel is connected with a water glass slurry inlet pipe 4, and the outlet end is provided with a wire drawing nozzle 11, and the mixing cavity 12 is connected with a mixed slurry outlet pipe. The first channel is composed of the cement slurry inlet pipe 3, a valve core and a jet pipe connected with the mixing cavity 12 in sequence, the valve core includes a high-pressure spring 8 and a steel ball 7 in abutting contact with the high-pressure spring 8 for preventing backflow of the cement slurry, and the inside of the jet pipe gradually converges in the direction of the cement slurry flow, and the critical surface intersecting with the mixing cavity 12 is the minimum cross section. The outer shell 1 includes a first shell section and a second shell section, the first shell section and the second shell section are connected through a detachable fixed connection of a connecting sleeve 9, the connecting sleeve 9 has a plurality of through holes 10 communicating the first shell section and the second shell section, and any through hole 10 is provided with the wire drawing nozzle 11 near one end of the mixing cavity 12; the second channel is composed of an annular space formed between the inner wall of the first shell section and the outer side wall of the first channel and a plurality of through holes 10; the first channel and the second channel meet in the mixing cavity 12 arranged in the second shell section. The second shell section is provided with a plurality of groups of spiral guides alternately arranged on the pipe wall downstream of the mixing cavity 12 along the fluid flow direction, and the guide directions of adjacent two groups of spiral guides are opposite. Any group of the spiral guides is composed of at least three spiral blades located at the same axial position and uniformly distributed on the inner wall of the second shell section.

[0077] The water pressure plug 2 is provided with a mixed slurry inlet pipe 14 connected with the mixed slurry outlet pipe through a detachable fixed connection of a wire connector 13; a pair of fixed joints 15 fixedly and oppositely arranged on the circumferential side wall of the mixed slurry inlet pipe 14, a rubber pipe 16 connecting the two fixed joints 15, and a water pressure plug pipe 5 arranged on any fixed joint 15 for communicating the space between the inner wall of the rubber pipe 16 and the outer wall of the mixed slurry inlet pipe 14.

[0078] Working principle:

[0079] When drilling is carried out, if the slurry mixing amount increases or significantly decreases, it indicates that there is water gushing or loss in the current stratum, and drilling is immediately stopped according to the standard construction steps. The following steps are sequentially performed:

[0080] Step ST100 tool positioning; the double-liquid slurry mixer including the mixer body and the water pressure plug 2 is assembled and ready for use; see the structure shown in Figure 2

[0081] Step ST200 geological survey to determine the mixing ratio of double slurry; the target hole is swept, the fracture is washed and the water pressure test is performed, and the mixing ratio of the cement slurry and the water glass is determined according to the water pressure test.​

[0082] Step ST300 system connection; the double-liquid slurry mixer is respectively communicated with the drill pipe, the water glass slurry pipe and the water pressure plug pipe, the hole is drilled to the depth of 1-2 meters above the first discovered water gushing or loss; in the embodiment, the distance between the double-liquid slurry mixer and the loss / water gushing point is controlled to be 1 meter±0.2 meters.

[0083] Step ST400 hole sealing; water is injected into the water pressure plug pipe to press, so that the water pressure plug 2 expands until a stable clamping structure is formed between the water pressure plug 2 and the hole wall, and the whole hole space is divided into the upper open cavity 19 and the lower closed cavity 20, as shown in Figure 9

[0084] Step ST500 double slurry injection; the cement slurry of a preset concentration is injected into the drill pipe and the water glass slurry is injected into the water glass slurry pipe at the same time, the injection amount and the grouting pressure are executed according to the preset scheme until the grouting is completed;

[0085] ​In the process of grouting, the cement slurry is pressurized by the slurry pump and then enters the valve core position from the cement slurry inlet pipe 3 and the reverse valve 6 in turn. Since the valve core has the function of blocking the cement slurry, when the pressure of the cement slurry delivered by the slurry pump is greater than the pressure of the valve core, the cement slurry overcomes the resistance of the valve core and enters the mixing chamber 12. At the same time, the water glass is delivered by the slurry pump and enters the water glass slurry inlet pipe 4, and then enters the second channel, and finally enters the mixing chamber 12 through the drawing jet head 11 to mix with the cement slurry in the first channel. Since the mixing chamber 12 has an expanding structure, the flow rate of the cement slurry can be reduced after entering the expanding structure to fully mix with the water glass slurry after drawing. In addition, the mixing chamber 12 is arranged in a converging structure along the fluid flow direction, which further extrudes the mixed slurry and changes the mixing uniformity of the mixed slurry, further improving the mixing uniformity of the slurry. After the double slurry is fully mixed in the mixing chamber 12, it enters the hole through the mixed slurry outlet pipe to the pre-set depth section to form a seal for the wall of the gushing hole section. The steel ball is used as the valve core component in this embodiment to provide reliable sealing and prevent backflow in the cement slurry containing particulate impurities. The steel ball seal is a linear seal, which can naturally avoid particulate matter in the cement slurry, and has better practicality and adaptability to the environment compared to the face seal one-way valve. The purpose of arranging the converging internal channel of the jet pipe is to accelerate the flow of the cement slurry in the jet pipe. The cross-sectional area of the cement slurry passing through the jet pipe at the moment it leaves the jet pipe is the smallest, and the flow rate of the cement slurry is the fastest at this time. When the cement slurry enters the mixing chamber 12 at the maximum speed, a local negative pressure is formed, which instantly sucks in the water glass slurry on the side to form a local cyclone. This internal cyclone is similar to the Venturi effect, which can actively promote the mixing of the water glass slurry and the cement slurry. After the cyclone, the mixing chamber 12 is expanded compared to the jet pipe, which rapidly decelerates and forms a limited turbulent effect in the mixing chamber 12. In combination with the converging mixing chamber 12 at the tail section, the slurry mixing is further more uniform. The through hole is arranged on the jet pipe and inclined along the fluid flow direction. Since the cement slurry in the jet pipe is faster along the flow direction, according to the Venturi principle, the closer the through hole is to the end of the jet pipe, the easier it is for the water glass on the side to enter the jet pipe and mix with the cement slurry. When the cement slurry and the water glass slurry are mixed and ejected into the mixing chamber 12, the process is repeated Figure 4The secondary mixing process is shown, so that the double slurry mixing is more sufficient. After the double slurry is mixed in the mixing chamber 12, when flowing through the downstream pipe wall, due to the contact with the spiral guide, under the guidance of the spiral guide, the mixed double slurry will flow along the guide. However, because the spiral guide is provided with multiple groups, and the guide direction between the adjacent two groups is opposite, that is, the previous group of spiral guide is clockwise, and the next group of spiral guide is counterclockwise, and so on. Then the mixed slurry flows repeatedly in the cycle of forward flow → turbulence → reverse flow → turbulence → forward flow, see Figure 6 as shown, Figure 6 The arrow in the middle indicates the spiral direction of the slurry flow. After multiple cycles, the mixed slurry will be mixed more uniformly. In this embodiment, the mixed slurry will undergo a maximum of three mixings. The first primary mixing is through the through hole provided on the slurry injection pipe, according to the Venturi principle to inhale mixing; the second mixing is in the mixing chamber 12, as shown in Figure 5 ; the third mixing is through the spiral guide, as shown in Figure 4 ; this can ensure the sufficiency of the double slurry mixing, and ensure the effectiveness of the water gushing plugging, and solve the problem of poor plugging or secondary water gushing. Figure 6

[0086] Step ST600 closes the system and takes out the tool; in order, close the cement slurry pipeline, the water glass slurry pipeline and the water pressure plug pipeline, take out and clean the double liquid slurry mixer, complete the current drilling grouting; continue to sweep the hole after the hole wall loss water gushing plugging.

[0087] Embodiment 3:

[0088] This embodiment particularly describes the hole sealing step of step ST400 in combination with the structure of the water pressure plug 2. On the basis of embodiment 2, further in combination with Figures 7-9 as shown, the water pressure plug 2 is provided with a mixed slurry inlet pipe 14 through the thread connector 13 detachable fixedly connected to the mixed slurry outlet pipe; a pair of fixed joints 15 fixedly and oppositely arranged on the circumferential side wall of the mixed slurry inlet pipe 14, a rubber pipe 16 connecting the two fixed joints 15, and a water pressure plug pipe 5 arranged on any one of the fixed joints 15 for communicating the space between the inner wall of the rubber pipe 16 and the outer wall of the mixed slurry inlet pipe 14.

[0089] Working principle: after the mixer is sent to the specified depth, the clean water is delivered into the water pressure plug pipe 5 through the ground pressurizing equipment. As the clean water injection increases, the rubber pipe 16 is constantly stressed and expanded. Because the fixed structure 15 and the mixed slurry inlet pipe 14 are closed structures, the rubber pipe 16 is constantly expanded and enlarged under the water pressure until it contacts the hole wall. Specifically as shown in Figure 8 ​As shown, at this time, as the rubber tube 16 continues to increase, the outer surface of the rubber tube 16 is in contact with the hole wall, forming a huge extrusion force, so that the rubber tube 16 and the hole wall are stationary due to the huge static friction, and play a fixed role. At this time, the mixed slurry enters the designated depth section of the hole through the mixed slurry inlet pipe 14 to implement the water inrush plugging. Due to the action of the water pressure plug pipe 5, the hole is divided into an upper open cavity 19 and a lower closed cavity 20, as shown in detail Figure 9 As shown, when the lower closed cavity 20 is plugged, the mixed slurry cannot enter the hole in the upper open cavity 19, which realizes the targeting and accuracy of plugging. The above operation not only has obvious plugging technical effect, but also can minimize the amount of slurry consumed. When deep hole construction is required, if water inrush is encountered in multiple hole sections, one section can be constructed and plugged, and this process is repeated until the preset depth. The method of the embodiment can meet the requirements of existing drilling holes of various depths and various difficult and complex geological conditions.

[0090] Based on the same inventive concept, the embodiment also provides another independent optimization scheme, that is, the fixed joint 15 in the above structure which is not provided with the water pressure plug pipe 5 is replaced by a movable joint 18 which is fixedly connected to the rubber tube 16, and the movable joint 18 is in sliding sealing connection with the outer side wall of the mixed slurry inlet pipe 14.

[0091] In order to meet the sliding requirements of the movable joint 18 and better realize the sealing effect, preferably, the inner side wall of the movable joint 18 is provided with a plurality of sealing rings 17 which are in abutment with the mixed slurry inlet pipe 14. The arrangement of the sealing rings 17 can further reduce the surface roughness requirement and the matching tolerance requirement between the inner diameter of the movable joint 18 and the outer diameter of the mixed slurry inlet pipe 14, so that the processing difficulty is lower, the subsequent maintenance is more convenient, the maintenance cost is more economical and convenient. The use of the movable joint 18 can obviously reduce the pressure increase value in the water pressure plug pipe 5 under the same fixing effect. Since the movable joint 18 is used, when the rubber tube 16 is subjected to pressure, the rubber tube 16 will expand and become larger in the radial direction while further shortening the axial length, which is more conducive to the deformation of the rubber tube 16, greatly reducing the problem that the rubber tube 16 cannot reliably abut and fix due to the loose hole wall geology because the rubber tube 16 cannot shorten in the axial direction but only expands in the radial direction. During continuous pressurization, the rubber tube 16 may burst due to the pressure exceeding the expansion limit. After the fixed joint 15 is replaced by the movable joint 18, the rubber tube 16 of the same material and size can obviously increase the effective radial expansion range while shortening the axial length, which is more effective in dealing with loose geological conditions and avoids the problem of bursting due to excessive expansion. At the same time, after the movable joint 18 is used, the requirement for the ground pressurizing equipment is also obviously reduced, the requirement for the pipe connected to the water pressure plug pipe 5 is also reduced, the material cost investment is obviously reduced, and the service life is prolonged.

[0092] Embodiment 4:

[0093] This embodiment is a technical solution parallel to Embodiment 2, and specifically as shown in Figure 10 and Figure 11 The upper end of the connecting sleeve 9 is provided with a plurality of through holes 10, and the lower end is provided with a slit 21 arranged in a ring and communicated with any one of the through holes 10. The slit 21 can be arranged in multiple layers concentrically to meet different water glass flow requirements, but any layer of slit 21 is communicated with the through hole 10 for discharging the water glass slurry into the mixing chamber 12. Compared with the wire drawing nozzle 11 in Embodiment 2, the design of the slit 21 has the following advantages: first, the same end surface area of the connecting sleeve 9 can have a larger flow capacity, avoiding the limitation of the maximum flow rate of the wire drawing nozzle 11; second, the design of the slit 21 can be micron-level, thereby realizing the blocking of the reverse flow of the cement slurry, and preventing the condensation and plugging of the connecting sleeve 9. When the minimum distance of the slit 21 is less than the particle size of the cement slurry, the reverse flow of the cement slurry can be effectively blocked, and the pipe plugging event can be avoided. When the slit 21 with the above small gap is used, if the flow requirement of the water glass slurry cannot be met, the number of slits 21 can be increased or the gap of the slit 21 can be expanded to solve the problem. When the gap of the slit 21 is expanded to increase the flow of the water glass slurry, a ball one-way valve 22 must be arranged at the upper end of the connecting sleeve 9 to prevent reverse flow, so that the cement slurry is blocked downstream of the connecting sleeve 9, and further pipe plugging is avoided. Of course, as a person skilled in the art, when using the double liquid slurry mixer according to the embodiment, the cement slurry booster pipeline must be closed first, and then the water glass slurry booster pipeline is closed, so as to further avoid the pipe plugging caused by the reverse flow mixing due to the higher pressure of the cement slurry conveying pipeline than that of the water glass slurry conveying pipeline. In this way, three safety measures are formed to avoid pipe plugging.

[0094] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various modifications and changes to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method of construction for cast-in-place drilling using a double slurry mixer, characterized by: The method comprises the following steps: Step ST100: tool positioning; assemble the double slurry mixer including the mixer body and the water pressure plug (2) and wait for use; Step ST200: determine the mixing ratio of the double slurry according to the geological survey; perform hole scanning, fissure flushing and water pressure test on the target hole, and determine the mixing ratio of the cement slurry and the water glass according to the water pressure test; Step ST300: system interfacing; connect the double slurry mixer with the drill pipe, the water glass slurry pipe and the water pressure plug pipe respectively, and lower the hole to 1-2 meters above the first discovered water gushing or loss; Step ST400: hole sealing; inject water into the water pressure plug pipe to pressurize, so that the water pressure plug (2) expands until a stable clamping structure is formed between the water pressure plug (2) and the hole wall, and the entire hole space is divided into an upper open cavity (19) and a lower closed cavity (20); Step ST500: double slurry injection; simultaneously inject the cement slurry of the preset concentration into the drill pipe and the water glass slurry into the water glass slurry pipe, and the injection amount and the grouting pressure are executed according to the preset scheme until the grouting is completed; Step ST600: close the system and take out the tool; close the cement slurry pipeline, the water glass slurry pipeline and the water pressure plug pipeline in sequence, take out and clean the double slurry mixer, and complete the current hole grouting; continue to scan the hole when the hole wall loss is sealed, and repeat steps ST100-ST600 when the second water gushing or loss point is found; The double slurry mixer is composed of a mixer body for mixing the cement slurry and the water glass and a water pressure plug (2) for fixing the mixer body at a specified depth in the hole and detachably connecting the water pressure plug (2) below the mixer body; The mixer body comprises an outer shell (1), a reverse valve (6) fixedly arranged in the outer shell (1) for dividing the inner cavity of the outer shell (1) into independent and closed first and second channels, the reverse valve (6) having a valve core for unidirectional conduction of the first channel, the first and second channels being communicated through a mixing cavity (12) arranged at the tail of the outer shell (1), the mixing cavity (12) having an expanding structure and an axial section gradually converging along the fluid flow direction, the inlet end of the first channel being connected with a cement slurry inlet pipe (3), the outlet end being arranged in a converging manner along the axial section in the fluid flow direction near the mixing cavity (12), and the inlet end of the second channel being connected with a water glass slurry inlet pipe (4), the outlet end being provided with a wire drawing nozzle (11), and the mixing cavity (12) being connected with a mixed slurry outlet pipe; The first channel is composed of the cement slurry inlet pipe (3), the valve core and the jet pipe communicating with the mixing cavity (12) in sequence, the valve core comprising a high-pressure spring (8) and a steel ball (7) in abutting contact with the high-pressure spring (8) for preventing backflow of the cement slurry, the jet pipe gradually converging along the cement slurry flow direction inside and the critical surface intersecting with the mixing cavity (12) being the minimum cross section, and the side wall of the jet pipe being provided with a plurality of through holes for absorbing the water glass slurry; The outer shell (1) includes a first shell segment and a second shell segment, which are connected by a detachable fixed connection connecting sleeve (9), the connecting sleeve (9) has a plurality of through holes communicating the first shell segment and the second shell segment, any of the through holes is provided with the wire drawing nozzle (11) near one end of the mixing chamber (12); the second channel is composed of an annular space formed between the inner wall of the first shell segment and the outer lateral wall of the first channel and a plurality of through holes; the first channel and the second channel meet in the mixing chamber (12) provided in the second shell segment; the second shell segment is provided with a plurality of groups of spiral guides on the pipe wall downstream of the mixing chamber (12) in the fluid flow direction, and the guide directions of adjacent two groups of spiral guides are opposite; any group of the spiral guides is composed of at least three spiral blades located at the same axial position and uniformly distributed on the inner wall of the second shell segment.

2. The construction method for cast-in-place drilling using a double slurry mixer according to claim 1, characterized in that: The water pressure plug (2) is provided with a mixed slurry inlet pipe (14) detachably fixedly connected to the mixed slurry outlet pipe by a wire connector (13); a pair of fixed joints (15) fixedly and oppositely arranged on the circumferential side wall of the mixed slurry inlet pipe (14), a rubber pipe (16) connecting the two fixed joints (15), and a water pressure plug pipe (5) arranged on any one of the fixed joints (15) for communicating the space between the inner wall of the rubber pipe (16) and the outer wall of the mixed slurry inlet pipe (14).

3. The method according to claim 2, wherein the method is characterized by: The fixed joint (15) without the water pressure plug pipe (5) is replaced by a movable joint (18) fixedly connected to the rubber pipe (16), and the movable joint (18) is in slidingly sealed connection with the outer lateral wall of the mixed slurry inlet pipe (14); the inner lateral wall of the movable joint (18) is provided with a plurality of sealing rings (17) in abutment with the mixed slurry inlet pipe (14).

4. The method of claim 1, wherein the method further comprises: The mixing ratio of cement slurry and water glass is 17:0.9-1.

1.

5. The method of claim 1, wherein the method further comprises: providing a double liquid slurry mixer. The outer shell (1) in claim 1 is replaced by the following structure: the outer shell (1) includes a first shell segment and a second shell segment, which are connected by a detachable fixed connection connecting sleeve (9), the connecting sleeve (9) has a plurality of through holes (10) communicating the first shell segment and the second shell segment, any of the through holes (10) is communicated by at least one annular slot (21) near one end of the mixing chamber (12); the second channel is composed of an annular space formed between the inner wall of the first shell segment and the outer lateral wall of the first channel and a plurality of through holes (10); the upper end of the through hole (10) is detachably connected with a ball-shaped one-way valve (22) for preventing backflow.

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