CN115387805A - Method for cleaning mud cake of slurry balance shield cutter head - Google Patents
Method for cleaning mud cake of slurry balance shield cutter head Download PDFInfo
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- CN115387805A CN115387805A CN202211156720.8A CN202211156720A CN115387805A CN 115387805 A CN115387805 A CN 115387805A CN 202211156720 A CN202211156720 A CN 202211156720A CN 115387805 A CN115387805 A CN 115387805A
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- 239000002002 slurry Substances 0.000 title claims abstract description 103
- 238000000034 method Methods 0.000 title claims abstract description 51
- 238000004140 cleaning Methods 0.000 title claims abstract description 18
- 239000002270 dispersing agent Substances 0.000 claims abstract description 119
- 238000009412 basement excavation Methods 0.000 claims abstract description 17
- 238000002791 soaking Methods 0.000 claims abstract description 16
- 230000008859 change Effects 0.000 claims abstract description 10
- 230000002441 reversible effect Effects 0.000 claims abstract description 9
- 238000003756 stirring Methods 0.000 claims abstract description 6
- 238000012360 testing method Methods 0.000 claims description 75
- 239000004927 clay Substances 0.000 claims description 67
- 238000002347 injection Methods 0.000 claims description 36
- 239000007924 injection Substances 0.000 claims description 36
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 24
- 239000000243 solution Substances 0.000 claims description 20
- 230000008569 process Effects 0.000 claims description 15
- 238000010276 construction Methods 0.000 claims description 14
- 239000007788 liquid Substances 0.000 claims description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 230000005484 gravity Effects 0.000 claims description 5
- 239000011259 mixed solution Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 231100000252 nontoxic Toxicity 0.000 claims description 3
- 230000003000 nontoxic effect Effects 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 238000010998 test method Methods 0.000 claims description 2
- 239000002689 soil Substances 0.000 description 15
- 230000000694 effects Effects 0.000 description 9
- 239000002245 particle Substances 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000011148 porous material Substances 0.000 description 5
- 230000002265 prevention Effects 0.000 description 5
- 229910000831 Steel Inorganic materials 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
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- 239000000047 product Substances 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 230000001360 synchronised effect Effects 0.000 description 3
- 239000002775 capsule Substances 0.000 description 2
- 238000007596 consolidation process Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 230000005641 tunneling Effects 0.000 description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/06—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining
- E21D9/08—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining with additional boring or cutting means other than the conventional cutting edge of the shield
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/06—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining
- E21D9/0642—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining the shield having means for additional processing at the front end
- E21D9/0678—Adding additives, e.g. chemical compositions, to the slurry or the cuttings
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- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Environmental & Geological Engineering (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Excavating Of Shafts Or Tunnels (AREA)
Abstract
The invention relates to a method for cleaning a slurry balance shield cutter disc mud cake, which comprises the following steps: stopping the shield, plugging the shield tail, and filling an excavation gap between the shield tail and the surrounding stratum to ensure that the shield tail is tightly attached to the surrounding stratum; closing the slurry circulating system and idling the cutter head, and fully stirring the slurry in the slurry tank by the cutter head until the torque value is stable; injecting a dispersant solution into the excavation gap between the shield shell and the surrounding ground layer through the radial grouting hole of the middle shield; and (3) alternately idling the cutter head in a forward and reverse rotation manner to soak the cabin, and observing the change condition of the torque of the cutter head in real time until the mud cakes are discharged and removed, or soaking the cabin for two or more times again until the mud cakes are cleaned. The mud cake cleaning machine can quickly and effectively clean mud cakes without opening the cabin, and is time-saving, labor-saving, money-saving and effective; the method is suitable for slurry balance shields of any type and under any working condition.
Description
Technical Field
The invention relates to the technical field of slurry balance shields, in particular to a method for cleaning a cutter head mud cake of a slurry balance shield.
Background
The mud-water balance principle of the mud-water balance shield is based on the mud permeation effect, and a good permeable mud film is formed on the excavation surface, so that the mud-water balance shield plays a role in maintaining the stability of the excavation surface; on the other hand, the grain composition of the slag soil on the excavation surface can be improved, and the smooth discharge of the slag soil is facilitated. The foundation for forming the permeable mud film is the result that fine particles in the slurry of the excavation cabin penetrate into the pores of the soil particles on the excavation surface, if the pores of the soil particles on the excavation surface are smaller (such as clay), the slurry particles are difficult to penetrate, and the mud film is difficult to form; on the contrary, in a sandy soil stratum, because the pores are relatively large, mud particles are easy to permeate, and a good mud film can be quickly generated, so that the mud water balance shield is more widely suitable for the construction of the sandy soil stratum from the viewpoint of mud film forming, which is approximately unified in the research of a plurality of related shield model selection.
In fact, because the incomplete scheduling problem of planning design and geological exploration of circuit, the balanced shield of muddy water can not guarantee that whole tunnelling process is all at the sand section, can pass through the construction of partly clay section sometimes, full section clay section even, and at this moment, not only is the formation quality problems of mud film, still derives a more serious construction difficult problem: the cutter head is used for forming mud cakes. The cutter head mud cake is actually the clay content in the excavation cabin which is too high, the clay is difficult to timely and effectively discharge and is accumulated in the cabin, meanwhile, the clay in the cabin is solidified on the cutter head due to the pressurization of muddy water (especially, the clay is solidified easily at the position with a small opening of the cutter head), when the clay with compactness is gradually pasted on the cutter head panel, the opening and the cutter, the whole cutter head is finally lost in cutting capacity, the shield has to be stopped to open the cabin to clean the mud cake, and the construction period and the economic benefit are seriously affected.
The formation of the cutter mud cake can be generally predicted and judged through three aspects, namely exploration based on stratum types: if the geological survey report is more detailed, the stratum into which the shield is about to enter can be accurately judged, and then the cutter head mud cake can be predicted and prepared according to the clay content of the section stratum; secondly, judging according to the actual construction parameters of the shield: if the shield cutter head is blocked by mud cakes, the shield can lose certain cutting capability, the simple understanding is that the cutter is sharp and sharp before the cutter head is not blocked by the mud cakes, and the cutter is stuck by the mud cakes and becomes blunt after the mud cakes are blocked, so that a soil body cannot be well cut; thirdly, the mud is analyzed according to the change of the mud index in the mud-water circulation system, and if the specific gravity of the mud discharged circularly is increased and the viscosity is increased, the fact that the muck contains a large amount of clay components is shown. In conclusion, the mud cake forming condition of the cutter disc can be accurately predicted and judged by combining the changes in the three aspects and comprehensively considering the changes.
However, even if the mud cake formation of the cutter head can be accurately predicted and judged, no effective method for cleaning the mud cake of the cutter head exists in the prior art, and the pursuit of shield construction on the construction period and the economic benefit cannot be met.
Disclosure of Invention
In view of the defects in the prior art, the main object of the present invention is to provide a method for cleaning a slurry balance shield cutterhead mud cake, so as to solve one or more problems in the prior art.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for cleaning mud cakes of a slurry balance shield cutter head comprises the following steps:
firstly, stopping the shield, plugging the shield tail, filling an excavation gap between the shield tail and the surrounding stratum, and ensuring that the shield tail is tightly attached to the surrounding stratum;
step two, closing the slurry circulating system and idling the cutter head, fully stirring the slurry in the slurry cabin by the cutter head, observing the torque change condition of the cutter head until the torque value is stable, and recording the torque value T 0 ；
Injecting a dispersant solution through the radial grouting hole of the middle shield, wherein the dispersant solution flows forward into the muddy water cabin along the excavation gap between the shield shell and the surrounding ground layer and does not flow backward into the shield tail;
step four, carrying out cabin soaking by alternately idling the cutter head in forward and reverse rotation, observing the change condition of the torque of the cutter head in real time, and:
if the idle time is more than a time lower limit t 1 Less than an upper time limit t 2 And the torque is reduced to a certain value and kept stable, the cutter head rotates forwards and the slurry circulating system is started, mud cakes fall off and are discharged, the torque of the cutter head is reduced again until the stability is achieved, and the mud cake is cleaned;
if the idle time is greater than the upper time limit t 2 And if the torque reduction amplitude is not obvious, starting a slurry circulating system, closing the slurry circulating system after partial mud cakes fall off and are discharged, and re-executing the third step and the fourth step to carry out secondary or multiple times of cabin soaking until the mud cakes are cleaned.
As an embodiment, in the fourth step, the step of immersing the capsule in the forward and reverse rotation alternate idling cutter head specifically comprises: and the cutter head is rotated reversely at the same rotating speed after the forward rotation torque is reduced to a certain value and is stabilized, and the cutter head is rotated normally at the same rotating speed after the reverse rotation torque is reduced to a certain value, and the steps are repeated until the torque value is not changed any more.
As an embodiment, in step four, the t 1 ＝2h，t 2 ＝7h。
As an embodiment, step three is preceded by the steps of:
1) Selecting the type of the dispersing agent, and selecting the dispersing agent capable of meeting the characteristic requirements;
2) Determining a dispersant index of the type based on the selected dispersant type, wherein the dispersant index comprises the concentration and the injection rate of the dispersant;
3) And (3) carrying out dispersant index test to test whether the dispersant index meets the requirements:
if so, converting the volume of the slurry in the slurry tank to obtain the injection amount of the dispersant solution;
if the concentration of the dispersant and the injection rate are not satisfied, firstly increasing the concentration of the dispersant and the injection rate, and if the concentration or the injection rate is increased to a certain extent to satisfy the requirements, converting the volume of the slurry in the slurry tank to obtain the injection amount of the dispersant solution; if the concentration is increased to a certain level or the injection rate is not satisfactory, the use of the dispersant of the type is abandoned, and the type of the dispersant is selected again.
As an embodiment, the dispersant properties should be:
1) The slurry is non-toxic, harmless and easily soluble in water, and does not generate strong chemical reaction when being mixed with slurry;
2) The pH value is between 6.5 and 7.5;
3) The viscosity of the Marfan funnel is less than or equal to 15s;
4) After the dispersant with determined indexes is added into the slurry, the slurry should meet the following requirements: the specific gravity is 1.08-1.12, the Ma funnel viscosity is 17-19 s, otherwise, the type of the dispersant needs to be selected again.
As an embodiment, the criterion of whether the concentration or the injection rate can be increased to meet the requirement is as follows: the concentration of the dispersant is not more than 10 percent, and the injection rate is not more than 15 percent.
As one embodiment, a test apparatus for performing a dispersant index test includes:
the mud box, rotating electrical machines are all installed to its box lateral wall all around, and rotating electrical machines disposes towards the inside rotating vane of box, and rotating vane stretches into certain distance to the box in.
As an embodiment, the dispersant indicator test method is:
1) Taking a clay sample from the site engineering, carrying out saturation treatment on the clay sample to be detected, and then preparing a clay test block;
2) Filling the slurry tank with a mixed solution of slurry and a dispersant, wherein the slurry index is consistent with that of the slurry in field engineering construction;
3) Starting the rotating motor and setting the rotating speed to ensure that the slurry stably flows in the box body;
4) Soaking clay test block in the mixed solution in the box body for about 1s, taking out the clay test block immediately, and weighing the initial mass m of the clay test block 0 ；
5) Soaking the clay test block into the mixed liquid in the slurry box again, measuring the mass m of the clay test block every 10min, and when the mass of the clay test block is reduced to m 0 At time/2, the time t at that time is recorded 50 When the clay test block is completely dissolved, recording the time t 100 ；
t 50 Less than or equal to 2h and t 100 If the index is less than or equal to 7 hours, the index of the dispersant meets the requirement, otherwise, the index does not meet the requirement.
As an embodiment, the test apparatus further comprises:
the wire netting is placed in the box body when in use and is used for placing clay test blocks;
one end of the stay bar is hung around the wire netting through a plurality of ropes.
In one embodiment, the clay test block is a 5 × 5 × 5cm cube, and the wire mesh is a 1 × 1cm grid woven with wires.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention can quickly and effectively clean mud cakes under the condition of not opening the cabin. Because the shield cabin opening is time-consuming, costly and dangerous work, the shield can not be opened under the condition that the shield cannot be tunneled due to serious mud cake accumulation of a cutter head unless the shield is in an unforeseen condition (such as the cutter is seriously abraded and needs to be changed, a bearing part is damaged and the like), therefore, the shield cabin opening device has the advantages that the mud cake can be effectively cleaned under the condition that the shield cabin is not opened, and the shield cabin opening device is time-saving, labor-saving, money-saving and effective.
(2) The method is suitable for the slurry balance shield of any type and under any working condition. The equipment utilized by the method is basically the own of the shield, such as a middle shield grouting pipeline, a muddy water circulating system, a synchronous grouting system and the like, other large-scale auxiliary equipment is not needed, only the change of the torque of the cutter head and the conversion of forward rotation and reverse rotation of the cutter head are combined in the process, and the operation is basically not difficult, so that the method can be used as a muddy water balance shield, and has strong applicability.
(3) The dispersant testing device with the unique design is simple and practical in structure, a testing method using the testing device can quickly and accurately verify whether a selected dispersant of a certain type can reach a required index, and the proper dispersant ensures that a cutter disc mud cake is quickly and effectively cleaned.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.
The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art can understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the functions and purposes of the present invention, shall fall within the scope covered by the technical contents disclosed in the present invention.
FIG. 1 is a flow chart of mud cake cleaning according to an embodiment of the present invention;
FIG. 2 is a schematic view of shield tail plugging and dispersant injection according to one embodiment of the present invention;
FIG. 3 (a) is a schematic diagram of a testing state of a dispersant indicator according to an embodiment of the present invention, (b) is a schematic diagram of an overall structure of a testing device, and (c) is a schematic diagram of a wire mesh structure;
FIG. 4 is a flow chart of a mud cake dispersant foam cabin method according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are described in further detail below with reference to the embodiments and the accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.
It is to be understood that the terms "comprises/comprising," "consists of … …," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product, apparatus, process, or method that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such product, apparatus, process, or method if desired. Without further limitation, an element defined by the phrases "comprising/including … …", "consisting of … …" does not exclude the presence of additional like elements in a product, apparatus, process or method that includes the element.
It should also be understood that the terms "mounted," "connected," "fixed," and the like are intended to be broadly construed, and may include, for example, a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the present invention, unless otherwise expressly stated or limited, the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on orientations or positional relationships illustrated in the drawings, merely for convenience in describing the present invention and to simplify the description, and do not indicate or imply that the device, component, or structure referred to must have a particular orientation, be constructed or operated in a particular orientation, and should not be construed as limiting the present invention.
In the slurry balance shield process, when a slurry cake is seriously accumulated on a cutter head of the slurry balance shield, the opening of the cutter head is blocked, and a cutter is stuck, most of cutting and slag discharging capabilities of the cutter head are lost, the tunneling construction cannot be carried out, and the most intuitive expression is that the shield thrust is large, the torque is large, and the propulsion speed is very low. At this time, the mud cake must be cleaned by a certain method.
As shown in fig. 1 and 2, the method for cleaning mud cakes of a slurry balance shield cutterhead specifically comprises the following steps:
1. plugging preparation work:
the shield is shut down, before the mud cake is to be cleaned, shield tail plugging work is firstly carried out, namely, grouting is carried out on the shield tail wall through the synchronous grouting holes, the grouting amount is controlled so as to completely plug the excavation gap behind the segment wall, and after the plugging of the gap behind the segment wall is finished, bentonite (or other clay plugging materials) and the like are injected through the synchronous grouting holes to fill the excavation gap between the shield tail and the ground layer, so that the shield tail part is ensured to be tightly attached to the ground layer around the shield tail part.
2. Idling the cutter head:
closing a slurry circulating system and idling a cutter head, enabling the cutter head to fully stir slurry in a slurry cabin, controlling the rotating speed of the cutter head to be 0.5 r/min (taking a 6 m-shaped diameter shield as an example, other types of shields can adjust the rotating speed according to actual working conditions as long as the rotating speed is stabilized at a determined value), observing the torque change condition of the cutter head, and recording a value T after the torque value is stabilized 0 。
3. Injecting a dispersing agent:
and converting the injection rate of a dispersant solution according to the selected optimal dispersant index and the volume of mud in the mud tank, injecting the dispersant solution through a radial grouting port at the middle shield position, wherein the dispersant solution flows forward into the mud tank along the excavation gap between the shield shell and the surrounding stratum, and the dispersant can only flow into the front of the shield shell but cannot flow into the rear shield tail position due to the plugging of the shield tail. The injection of the dispersant is shown in figure 2.
4. Bubble chamber completion and stop conditions:
alternately idling the cutter head in forward and reverse rotation, soaking the dispersing agent in the muddy water cabin in the stirring process, observing the change condition of the torque of the cutter head in real time, reversing the cutter head at the same rotating speed after the torque is reduced to a certain value and stabilized, and then rotating forward after the torque in reverse rotation is reduced to a certain value, repeating the steps until the torque value is not changed, wherein the soaking time (namely the idling time of the cutter head) is more than a time lower limit t 1 Less than an upper time limit t 2 The cutter head is rotated forward and a mud circulation system is opened, the mud proportion is reduced due to the dropping and discharging of mud cakes in the cabin, the torque of the cutter head is reduced again until the whole cabin soaking process is finished after the torque of the cutter head is stabilized.
If the time for soaking the cabin is greater than the upper time limit t 2 (at the moment, the torque of the cutter head is relatively stable but the reduction amplitude is not obvious), the slurry circulating system is opened for a period of time, the slurry circulating system is closed after part of dropped mud cakes are discharged, and the cabin is soaked for two times or more according to the steps.
According to the formation characteristics and the type selection of the dispersing agent, the lower limit t1 of the time is 2h, and the upper limit t2 of the time is 7h. According to the test, the critical time of half mass of the clay test block dissolved is 2h, and the critical time of complete dissolution of the clay test block is 7h. In actual construction, when the clay dissolves half the mass, the mud water concentration in the mud water cabin can change to a certain extent, so that subsequent dissolution is influenced, at the moment, a mud circulating system needs to be opened to discharge mud, and meanwhile, the mud in the mud water cabin is updated, and the steps are repeated until mud cakes completely fall off and are discharged.
As described above, the type of the dispersant is selected before the dispersant is injected, and a dispersant that can satisfy the characteristic requirements is selected.
At present, a plurality of manufacturers for producing the dispersing agent for the tunnel at home and abroad relate to the confidentiality problem of companies, the components of the dispersing agent produced by each manufacturer are different, and sometimes the dispersing agent can be distinguished from apparent phenomena such as appearance color, viscosity, smell and the like, and the dispersing effects of various dispersing agents are different.
The dispersing agent adopted by the capsule method of the invention has the following characteristics:
(1) The slurry is non-toxic, harmless and easily soluble in water, and does not produce strong chemical reaction when mixed with slurry, such as generation of a large amount of bubbles, generation of precipitates or viscous substances and the like.
(2) The pH value is ensured to be between 6.5 and 7.5, and the dispersing effect of the dispersing agent is prevented from being influenced by the neutralization of the peracid or over-alkali dispersing agent solution and acid-base substances contained in the stratum, such as a large amount of silicate contained in a sand layer, carbonate contained in a viscous soil layer and the like. (the red and yellow soil widely distributed in the south China and the southwest China is acidic, the pH value is mostly between 4.5 and 5.5, and the soil of the north China and the northwest China mostly contains CaCO 3 Is alkaline, and the pH value is generally between 7.5 and 8.5).
(3) The viscosity of the Marfan funnel is less than or equal to 15s, (the viscosity of the Marfan funnel refers to the time required for 700ml of liquid in the Marfan funnel to drip 500ml of liquid, the viscosity of pure water is 14 s), and the liquid with high viscosity influences the penetration effect of slurry to a soil layer, so that the dissolving effect of the dispersing agent is influenced.
4) After the dispersant with determined indexes is added into the slurry, the slurry must be ensured to be in the following range: the specific gravity is 1.08-1.12, and the Ma funnel viscosity is 17-19 s. And if the requirement cannot be met, the selection of the dispersant type is carried out again.
The dispersant can not be directly applied after being selected, and a dispersant index test is carried out, wherein the dispersant index comprises the concentration of the dispersant and the injection rate, the concentration of the dispersant is the adding amount of the dispersant in a certain volume of water, and the injection rate is the adding amount of the dispersant solution in the volume of the slurry, namely the ratio of the volume of the dispersant solution to the volume of the slurry to be added. Generally, the higher the concentration and injection rate of the dispersant is, the faster the rate of dissolving clay is, but a certain peak value is reached, that is, under a certain index, even if the concentration and injection rate are increased, the clay dissolution speed is not increased, so that it is necessary to first test whether a certain brand and a certain type of dispersant can reach the standard.
In order to test the index of the dispersant and determine whether the type of the selected dispersant meets the requirement of dispersing and cleaning mud cakes in a certain stratum, the invention designs a simple and practical dispersant index testing device in a targeted manner, and as shown in fig. 3, the testing device at least comprises:
mud case 1, its lateral wall all installs rotating electrical machines 2 all around, and rotating electrical machines 2 disposes towards the inside rotating vane of box, and rotating vane stretches into certain distance to the box in.
As a specific example, as shown in fig. 3, the test apparatus further has:
the wire netting 3 is placed in the box body when in use and is used for placing the clay test block 4;
one end of the stay bar 5 is hung around the iron wire net through a plurality of ropes 6.
The plurality of ropes 6 may be steel wire ropes which are gathered at one end of the stay 5 and hung on the stay by a detachable hook 7.
The mud box 1 is of a square structure, four rotating motors 2 are arranged on the peripheral side walls of the mud box, four corners of a wire mesh 3 are connected with steel wire ropes with hooks 7, and the steel wire rope hooks are directly hung by support rods 5. The blade of rotating electrical machines stretches into the inside certain distance of box in order to ensure can be to the mud stirring in the box abundant, nevertheless can not touch wire netting and clay sample. The rotating motor is used for driving the slurry in the slurry box to flow through rotation, so that on one hand, the slurry can be prevented from being accumulated and precipitated, and the effect of a dispersing agent is influenced; on the other hand, the dynamic process of the circulation of the slurry in the slurry cabin of the slurry balance shield slurry pipeline can be completely simulated. The rotating speed of the rotating motor is set according to the flow rate of the circulation slurry pipeline, the shield types of different projects and the slurry flow rate of the stratum characteristics are different, for example, the slurry flow rate of a certain project is 2-4 m/s, the diameter of the slurry pipeline is 0.3m, the shield excavation diameter is 6.28m, the width of the slurry cabin is about 1.9m, and the calculated slurry flow is about 0.57-1.13 m 3 And/s, the flow speed of the slurry in the muddy water cabin is converted into 0.048-0.096 m/s on average, so that the rotating speed of the motor is well controlled in the test process, and the flow speed of the slurry near the clay test block is as high as possible.
The wire netting is 1 x 1 cm's net that the iron wire was worked out the combination and is formed, and its four minutes is fixed a wire rope respectively, and wire rope's other end cover has the couple of dismantling, and the couple directly links to each other with the vaulting pole.
The wire netting is filled with a cubic clay test block with the volume of 5 multiplied by 5cm, the clay test block needs to be obtained from an engineering stratum and manufactured, and finally the clay test block is placed into a slurry box through a support rod for testing.
In addition, the device can also test the dispersion effect of dispersant to the clay after the certain time concreties, like this, only need with the clay test block adopt behind the consolidation apparatus or other consolidation modes concreties a period again put on the wire netting and disperse can.
The method for testing the index of the dispersant in the specific test comprises the following steps:
taking a clay sample from site engineering, removing large-particle-size soil particles in the soil sample according to the actual situation of site sampling according to the situation, carrying out saturation treatment on the clay sample to be detected, and then preparing the clay sample into a clay test block 4; since clay is used for causing the mud cake of the cutter head, and other types of soil (such as sandy soil and the like) are not used, the clay is sampled from the site and tested, so that the action effect of the selected dispersing agent on the engineering stratum can be ensured. In addition, the tested clay needs to be saturated, the saturation treatment is to fill the pores of the clay with water and discharge the air influence in the pores, the slurry in the slurry cabin in the engineering is filled with slurry, the clay adhered to the cutter head is in the slurry, so the clay is in a saturated state and can be matched with the actual engineering, and a certain air influence adhesion effect exists among unsaturated clay particles, so the saturated clay is adopted for testing.
The mud tank 1 is filled with mixed liquid of mud and a dispersant (to-be-measured concentration index), and the mud index is consistent with that during engineering construction;
starting the rotating motor 2 and setting the rotating speed to ensure that the slurry stably flows in the tank;
after the slurry flows stably, the clay test block 4 is placed on the wire netting 3 and is placed into the slurry box 1 by means of the support rods 5, so that the clay test block 4 is immersed into the mixed liquid for about 1s and is immediately immersed into the mixed liquidTaking out and weighing the initial mass m of the clay test block 4 0 (ii) a When the test block is put into the test block, the position of the test block keeps a certain distance from the motor blade, and the test block cannot be interfered by the motor blade.
Immersing the clay test block 4 into the mixed liquid in the slurry box 1 again, measuring the mass m of the clay test block 4 every 10min, and when the mass of the clay test block 4 is reduced to m 0 At time/2, the time t at that time is recorded 50 ，
Finally, when the clay test block 4 is completely dissolved, recording the time t at the moment 100 。
After the test is finished, judging whether the index of the dispersing agent in the test process meets the requirement:
if the slurry volume meets the requirement, the currently selected dispersant type meets the requirement of the stratum shield to be used, the slurry volume can be used for cleaning mud cakes in the current stratum shield process, and then the injection amount of the dispersant solution is obtained according to the conversion of the volume of the slurry in the mud water cabin;
if the concentration of the dispersant and the injection rate are not satisfied, firstly increasing the concentration of the dispersant and the injection rate, and if the concentration or the injection rate is increased to a certain extent to satisfy the requirements, converting the volume of the slurry in the slurry tank to obtain the injection amount of the dispersant solution; if the concentration or the injection rate cannot meet the requirement at a certain level or the concentration is extremely high, the requirement can be met only marginally, and then the dispersant type is selected again without using the dispersant of the type.
According to the actual project, the concentration of the used dispersant is about 5%, and the injection rate is generally not more than 10%, therefore, the above-mentioned standard for determining whether the required concentration or injection rate can be satisfied after increasing a certain concentration or injection rate is as follows: the concentration of the dispersant is not more than 10 percent, the injection rate is not more than 15 percent, if the upper limit is reached, the requirement can not be met, or the requirement can not be met only if the upper limit is exceeded, the type of the dispersant is not suitable, and the type of the dispersant should be selected again.
In the present invention, specifically, the dispersant index requirement needs to be t 50 Less than or equal to 2h and t 100 And (7) h or less is regarded as meeting the requirement, otherwise, the requirement is not met.
The mud cake cleaning method disclosed by the invention has the advantages that the time for cleaning mud cakes once by adopting the dispersing agent cabin soaking method is at least 12-18 h, and the adoption of the cabin cleaning method is not economical and wastes the construction period, which is only necessary to clean the mud cakes.
Certainly, under the condition that mud cake formation does not occur or is not serious in the shield process, the dispersant selected by the testing device and the testing method can be adopted in advance for mud cake prevention, namely, the invention also provides a mud cake prevention method which does not influence the normal construction, as shown in fig. 4, the mud cake prevention method and the cleaning method are similar and both adopt a cabin soaking principle to fully exert the characteristics of the dispersant, but are different from the cleaning of mud cake by a shutdown cabin soaking cabin, the dispersant cabin soaking method for mud cake prevention is to directly add dispersant solution into a mud returning pool of a mud circulating system in the process of digging without shutdown, the concentration and the injection rate of the dispersant solution are determined according to the indexes determined by the dispersant index test and the mud volume in the mud returning pool, and if the indexes of the dispersant determined by the test are as follows: volume ratio dispersing agent: slurry =1, then the dispersant is injected in an amount converted from the volume of slurry in the mud pit. The dispersing agent is required to be injected into the slurry returning pool once every 5 rings of the shield tunneling.
And similarly, the condition of the mud water cabin is observed in real time, and if the thrust and torque parameters of the cutter head are stable, the specific gravity and the viscosity of the mud do not increase any more, and the mud cake prevention is finished.
Thus, it should be understood by those skilled in the art that while exemplary embodiments of the present invention have been illustrated and described in detail herein, many other variations and modifications can be made, which are consistent with the principles of the invention, from the disclosure herein, without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.
Claims (10)
1. A method for cleaning mud cakes of a slurry balance shield cutter head comprises the following steps:
firstly, stopping the shield, plugging the shield tail, filling an excavation gap between the shield tail and the surrounding stratum, and ensuring that the shield tail is tightly attached to the surrounding stratum;
step two, closing the slurry circulating system and idling the cutter head, fully stirring the slurry in the slurry cabin by the cutter head, observing the torque change condition of the cutter head until the torque value is stable, and recording the torque value T 0 ；
Injecting a dispersant solution through the radial grouting hole of the middle shield, wherein the dispersant solution flows forward into the muddy water cabin along the excavation gap between the shield shell and the surrounding ground layer and does not flow backward into the shield tail;
step four, alternately idling the cutter head in a forward and reverse rotation manner to soak the cabin, observing the change condition of the torque of the cutter head in real time, and:
if the idle time is more than a time lower limit t 1 Less than an upper time limit t 2 And the torque is reduced to a certain value and kept stable, the cutter head rotates forwards and the slurry circulating system is started, mud cakes fall off and are discharged, the torque of the cutter head is reduced again until the stability is achieved, and the mud cake is cleaned;
if the idle time is greater than the upper time limit t 2 And if the torque reduction amplitude is not obvious, starting a slurry circulating system, closing the slurry circulating system after partial mud cakes fall off and are discharged, and re-executing the third step and the fourth step to carry out secondary or multiple times of cabin soaking until the mud cakes are cleaned.
2. The method of claim 1, wherein:
in the fourth step, the step of alternately idling cutter head forward and backward to soak the cabin specifically comprises the following steps: and the cutter head is rotated reversely at the same rotating speed after the forward rotation torque is reduced to a certain value and stabilized, and the cutter head is rotated normally at the same rotating speed after the reverse rotation torque is reduced to a certain value, and the process is repeated until the torque value is not changed.
3. The method of claim 1, wherein:
in step four, the t 1 ＝2h，t 2 ＝7h。
4. The method of claim 1, wherein step three is preceded by the steps of:
1) Selecting the type of the dispersing agent, and selecting the dispersing agent capable of meeting the characteristic requirements;
2) Determining a dispersant index of the type based on the selected dispersant type, wherein the dispersant index comprises a dispersant concentration and an injection rate;
3) And (3) carrying out dispersant index test to test whether the dispersant index meets the requirement:
if so, converting the volume of the slurry in the slurry tank to obtain the injection amount of the dispersant solution;
if the concentration of the dispersant and the injection rate are not satisfied, firstly increasing the concentration of the dispersant and the injection rate, and if the concentration or the injection rate is increased to a certain extent to satisfy the requirements, converting the volume of the slurry in the slurry tank to obtain the injection amount of the dispersant solution; if the concentration is increased to a certain level or the injection rate is not satisfactory, the use of the dispersant of the type is abandoned, and the type of the dispersant is selected again.
5. The method of claim 4, wherein the dispersant characteristics are such that:
1) The slurry is non-toxic, harmless and easily soluble in water, and does not generate strong chemical reaction when being mixed with slurry;
2) The pH value is between 6.5 and 7.5;
3) The viscosity of the Marfan funnel is less than or equal to 15s;
4) After the dispersant with determined indexes is added into the slurry, the slurry should meet the following requirements: the specific gravity is 1.08-1.12, the Ma funnel viscosity is 17-19 s, otherwise, the type of the dispersant needs to be selected again.
6. The method of claim 4, wherein:
the standard of whether the requirement can be met after the certain concentration or the injection rate is improved is as follows: the concentration of the dispersant is not more than 10 percent, and the injection rate is not more than 15 percent.
7. The method of claim 4, wherein the testing device used to perform the dispersant index test comprises:
the mud case, its box lateral wall all installs the rotating electrical machines all around, and the rotating electrical machines disposes towards the inside rotating vane of box, and rotating vane stretches into the certain distance to the box in.
8. The method of claim 7, wherein the dispersant index test method is:
1) Taking a clay sample from the site engineering, carrying out saturation treatment on the clay sample to be detected, and then preparing a clay test block;
2) Filling a slurry tank with a mixed solution of slurry and a dispersing agent, wherein the slurry index is consistent with that of the slurry in the field engineering construction;
3) Starting the rotating motor and setting the rotating speed to ensure that the slurry stably flows in the box body;
4) Soaking clay test block in the mixed solution in the box body for about 1s, taking out the clay test block immediately, and weighing the initial mass m of the clay test block 0 ；
5) Soaking the clay test block into the mixed liquid in the slurry box again, measuring the mass m of the clay test block every 10min, and when the mass of the clay test block is reduced to m 0 At time/2, record time t at that time 50 When the clay test block is completely dissolved, recording the time t 100 ；
t 50 Less than or equal to 2h and t 100 If the time is less than or equal to 7 hours, the index of the dispersant meets the requirement, otherwise, the index does not meet the requirement.
9. The method of claim 7, wherein the testing device further comprises:
the wire netting is placed in the box body when in use and is used for placing clay test blocks;
one end of the stay bar is hung around the wire netting through a plurality of ropes.
10. The method of claim 9, wherein:
the clay test block is a 5 x 5cm cube test block, and the wire netting is a 1 x 1cm grid woven by iron wires.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116297105A (en) * | 2023-03-30 | 2023-06-23 | 浙江大学 | Device and method for simulating three-dimensional dynamic slurry permeation test under supergravity |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116297105A (en) * | 2023-03-30 | 2023-06-23 | 浙江大学 | Device and method for simulating three-dimensional dynamic slurry permeation test under supergravity |
| CN116297105B (en) * | 2023-03-30 | 2023-11-28 | 浙江大学 | Device and method for simulating three-dimensional dynamic slurry permeation test under supergravity |
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