CN116517583A - Construction method for generating filter cake by grouting shield tail of water-rich powder fine sand layer and filling shield tail gap - Google Patents
Construction method for generating filter cake by grouting shield tail of water-rich powder fine sand layer and filling shield tail gap Download PDFInfo
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- 239000012065 filter cake Substances 0.000 title claims abstract description 82
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 49
- 239000004576 sand Substances 0.000 title claims abstract description 46
- 238000010276 construction Methods 0.000 title claims abstract description 33
- 239000000843 powder Substances 0.000 title claims description 3
- 239000002002 slurry Substances 0.000 claims abstract description 130
- 239000002689 soil Substances 0.000 claims abstract description 39
- 239000004568 cement Substances 0.000 claims abstract description 32
- 230000001360 synchronised effect Effects 0.000 claims abstract description 21
- 239000003673 groundwater Substances 0.000 claims abstract description 12
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 230000005641 tunneling Effects 0.000 claims abstract description 5
- 229920000663 Hydroxyethyl cellulose Polymers 0.000 claims abstract description 3
- 239000004354 Hydroxyethyl cellulose Substances 0.000 claims abstract description 3
- 239000000440 bentonite Substances 0.000 claims abstract description 3
- 229910000278 bentonite Inorganic materials 0.000 claims abstract description 3
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000010881 fly ash Substances 0.000 claims abstract description 3
- 235000019447 hydroxyethyl cellulose Nutrition 0.000 claims abstract description 3
- 239000002245 particle Substances 0.000 claims description 25
- 238000009792 diffusion process Methods 0.000 claims description 24
- 230000000694 effects Effects 0.000 claims description 24
- 239000011148 porous material Substances 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 14
- 238000005325 percolation Methods 0.000 claims description 14
- 238000012360 testing method Methods 0.000 claims description 12
- 230000008569 process Effects 0.000 claims description 11
- 230000008859 change Effects 0.000 claims description 6
- 238000005056 compaction Methods 0.000 claims description 6
- 238000006073 displacement reaction Methods 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- 230000004044 response Effects 0.000 claims description 3
- 230000035882 stress Effects 0.000 claims 2
- 230000032683 aging Effects 0.000 claims 1
- 230000035699 permeability Effects 0.000 claims 1
- 230000000704 physical effect Effects 0.000 claims 1
- 238000001179 sorption measurement Methods 0.000 claims 1
- 238000009991 scouring Methods 0.000 abstract description 2
- 230000004888 barrier function Effects 0.000 abstract 1
- 230000015572 biosynthetic process Effects 0.000 description 14
- 238000010586 diagram Methods 0.000 description 6
- 238000011010 flushing procedure Methods 0.000 description 4
- 238000011160 research Methods 0.000 description 4
- 238000007569 slipcasting Methods 0.000 description 4
- 239000012530 fluid Substances 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000012466 permeate Substances 0.000 description 3
- 241000537371 Fraxinus caroliniana Species 0.000 description 2
- 235000010891 Ptelea trifoliata Nutrition 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
Classifications
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D11/00—Lining tunnels, galleries or other underground cavities, e.g. large underground chambers; Linings therefor; Making such linings in situ, e.g. by assembling
- E21D11/04—Lining with building materials
- E21D11/10—Lining with building materials with concrete cast in situ; Shuttering also lost shutterings, e.g. made of blocks, of metal plates or other equipment adapted therefor
- E21D11/105—Transport or application of concrete specially adapted for the lining of tunnels or galleries ; Backfilling the space between main building element and the surrounding rock, e.g. with concrete
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
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- Engineering & Computer Science (AREA)
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- Architecture (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
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Abstract
The invention discloses a rapid construction method for generating a filter cake layer by synchronous grouting of shield tails of a water-rich fine sand layer, which mainly comprises the following steps: establishing a filter cake growth rate equation based on the theory of capillary groups and the law of conservation of mass; according to calculation, in the fine sand layer with the porosity of 0.38, the water-cement ratio of the slurry is controlled to be 0.7-0.8, so that a filter cake can be quickly generated; preparing a novel slurry with water dispersibility, wherein the water-gel ratio is 0.72, the gel-sand ratio is 0.80, the mixing amount of fly ash is 5%, the mixing amount of bentonite is 14.94% and the mixing amount of hydroxyethyl cellulose is 0.9%; grouting pressure is 0.4Mpa, grouting rate is 180%, tunneling speed of shield machine is 40-50 mm/min, grouting quantity ratio of upper and lower grouting holes is 1.5:1, and position relation is theta Upper part ：θ Lower part(s) =3pi/10: the surface settlement is small at pi/5. Aiming at the problem that the synchronous grouting slurry of the water-rich fine sand layer is eroded by groundwater, the slurry generates a filter cake layer on the surface of a soil body and forms a water stop barrier, so that the slurry on the inner side of the filter cake layer is ensured to be subjected to small groundwater scouring force, and the gap between the shield tails is filled rapidly.
Description
Technical Field
The invention relates to the field of tunnel engineering, in particular to a synchronous grouting construction of a shield tail and a method for determining a slurry ratio.
Background
Along with the continuous development of the underground engineering field of China, the tunnel construction of China is in a high-speed development period, the shield construction also faces various complex strata, and the process involves a large number of synchronous grouting of shield tails. When the shield passes through the water-rich stratum, the slurry can be dispersed under the action of the flushing force of groundwater, so that the slurry is not uniformly filled in the shield tail gap, the earth surface is greatly settled, the construction safety is endangered, a regular annular shield tail gap is difficult to form after the shield is excavated for round gravel or fine sand stratum with poor self-stability, the stratum collapses towards the shield tail gap quickly, and if the slurry cannot timely fill in the shield tail gap and bear the unloading pressure of the stratum, the earth surface is greatly settled, the tunnel stability and the earth surface building are greatly influenced, and a series of safety problems are caused.
For a long time, in order to solve the problems during synchronous grouting of the shield tails, a large number of students develop experiments and theoretical researches, and in the aspect of the experiments, different types of additives are selected for different strata, the proportion of slurry suitable for the strata is prepared, and the grouting equipment is independently researched and developed to simulate the shield grouting, wherein the method mainly comprises the research on the changes of the slurry speed, the water content of the strata, the density and the like in the grouting process; for the numerical simulation aspect, based on finite element software such as comsol and the like, researching the diffusion rule of shield grouting slurry and the influence of the shield grouting slurry on surface subsidence under different construction parameters; in the aspect of theoretical research, for slurry filling diffusion, based on a crack grouting theory, a diffusion equation of Newton fluid, bingham fluid and power flow type fluid in a shield tail gap is established, slurry timeliness is respectively introduced into a formula, the rationality of the formula is enhanced, for a slurry permeation diffusion stage, partial scholars establish a slurry permeation diffusion equation considering a percolation effect based on Darcy's law and a linear permeation law, and for a slurry compaction diffusion stage, a disturbance range theoretical formula of the slurry compaction diffusion stage on a coating is established based on a column hole or ball hole expansion theory.
Currently, most scholars default the slurry diffusion stage to a single stage, and a diffusion equation considering the slurry percolation effect is yet to be studied, and is actually affected by the formation percolation effect, the slurry can generate a filter cake on the surface of the formation, i.e. the slurry can permeate and diffuse first and then diffuse compactly. The slurry plays a role in filling the shield tail gap, supporting the stratum collapsed under the unloading effect, timely sealing the slurry in the shield tail gap into a ring to ensure the stability of the stratum, and in actual engineering, if the filter cake can be ensured to be generated in the shield tail gap as soon as possible, the underground water can be effectively blocked, the slurry at the inner side of the filter cake can be ensured to be rapidly filled in the shield tail gap, so that the research on the generation speed of the filter cake under the percolation effect of the slurry is extremely necessary.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a rapid construction method for generating a filter cake layer by synchronous grouting of a shield tail of a water-rich fine sand layer, which establishes a filter cake growth rate equation suitable for synchronous grouting of the shield tail based on a capillary group theory, a mass conservation law and a momentum conservation law, and uses the rapid generation of the filter cake as a final aim by comparing the generation rate of the filter cake under different factors, so as to develop slurry water-cement ratios with suitability for different pore ratio strata, prepare novel slurry with water-resistant dispersibility by an indoor test, and adopt a shield tail grouting similar model test system to determine shield tail grouting construction parameters, and provides a rapid construction method for generating the filter cake layer by synchronous grouting of the shield tail of the water-rich fine sand layer, so as to realize the aims and advantages of the invention, and the rapid construction method comprises the following steps:
step 1: when slurry permeates and diffuses in the fine sand layer, slurry particles are influenced by the percolation effect of fine sand, slurry particles can be deposited in soil layer pores and gradually block the soil layer pores to finally form a filter cake, the water-rich fine sand layer contains rich groundwater, a slurry diffusion equation considering the percolation effect is established for the groundwater displacement effect in the soil body when the slurry diffuses in the soil layer, and a filter cake growth rate equation is further deduced;
establishing a filter cake growth rate equation includes:
preferably, based on the theory of capillary group and the law of conservation of mass, a filter cake growth rate equation formed by the permeation and diffusion of slurry in a water-rich fine sand layer is established, and the viscosity timeliness of the slurry is considered, wherein the formula parameters comprise grouting pressure, soil layer grain composition and slurry water-cement ratio, and the formula parameters comprise the following steps:
considering the displacement effect of slurry on groundwater in soil when the slurry diffuses in soil layer, and establishing a filter cake growth thickness equation considering the percolation effect based on capillary group theory:
n 0 for the initial porosity of the formation,
n is the formation porosity, determined by:
k is the initial pore radius of the formation, which can be determined by:
phi is the formation porosity, and can be determined by:
gamma is the volume weight of the soil body,
γ s is the volume weight of the soil particles,
w is the water content of the stratum;
k 1 taking the KC constant as 180;
is the initial slurry particle volume fraction;
p c the pressure at the filter cake and formation interface is determined by the following formula:
p c ＝γ w p 0 (5)；
p 0 is grouting pressure;
p a is a dimension parameter;
for the slurry-related coefficients, taken herein as-34;
τ 0 yield shear stress for the slurry;
μ 0 the initial viscosity Pa.s of the slurry;
b is a viscosity timeliness parameter of the slurry;
d 10 the diameter of the soil particles in the soil layer is corresponding to 10 percent;
d 85 the particle diameter is corresponding to 85 percent of the cement particles;
ρ c is the density g/cm of cement particles 3 ；
w/c is the water-ash ratio of the slurry;
deriving it with respect to time to obtain the filter cake growth rate equation:
the growth thickness and the growth rate of the cement filter cake can be obtained through the formula (1) and the formula (6), and the cement slurry water-cement ratio range required by grouting the shield in the water-rich fine sand layer can be preliminarily determined through comparing the change curve of the growth rate of the filter cake.
Step 2: the filter cake can prevent the underground water from flushing the slurry after being formed at the shield tail, so that the effect of plugging the underground water is achieved, the slurry at the inner side of the filter cake can be ensured to rapidly fill the gap of the shield tail and form a closed hoop, namely, the filter cake is formed earlier, and the grouting construction in the water-rich fine sand layer is facilitated to be rapidly completed;
step 3: aiming at a filter cake generation rate equation, the water-cement ratio of the slurry suitable for the water-rich fine sand layer is provided, and for the fine sand layer with the porosity of 0.38, the water-cement ratio is controlled to be 0.7-0.8, and the novel slurry with water dispersibility is prepared through an indoor test: the water-cement ratio is 0.72, the cement-sand ratio is 0.80, the mixing amount of the fly ash is 5%, the mixing amount of the bentonite is 14.94% and the mixing amount of the hydroxyethyl cellulose is 0.9%, so that the slurry has the capability of resisting the flushing of underground water, and can permeate and diffuse in a shield tail gap to generate a filter cake;
step 4: the self-developed shield tail synchronous grouting similar model test system is characterized in that grouting pressure is controlled to be 0.4Mpa, grouting rate is controlled to be 180%, tunneling speed of a shield machine is 40-50 mm/min, and when the ratio of grouting amounts of upper grouting holes to lower grouting holes is 1.5:1, the ground surface settlement is small; because in the synchronous slip casting work progress of actual shield tail, receive thick liquid self gravity and shield tail clearance irregularity influence, the thick liquid that is located last slip casting hole department can flow to shield tail clearance bottom and lead to shield tail clearance top thick liquid filling rate lower and be difficult for generating the filter cake, can obtain from upper and lower slip casting hole grouting amount relation from top to bottom slip casting hole location relation: θ Upper part ：θ Lower part(s) =3pi/10: pi/5, namely, the upper grouting pipe can be properly moved to the top of the shield tail gap in the actual construction process, the position of the lower grouting hole is determined according to the position relation, the top of the shield tail gap is ensured to be fully filled with slurry, and the formation of a filter cake is ensured.
Preferably, for the water-rich fine sand layer with poor self-stability, after the shield is driven in, the soil body is influenced by unloading effect and collapses towards the shield tail gap, so that the formed shield tail gap has irregularity, slurry is firstly permeated and diffused in the shield tail gap, after a filter cake formed by slurry congestion of a soil layer pore is formed into a hoop at the shield tail, slurry pressure acts on the filter cake, the slurry pressure is converted into effective force to act on the soil layer through the filter cake, namely, the slurry enters a compaction and diffusion stage, the efficiency of filling the shield tail gap in the slurry water-rich fine sand layer can be effectively improved by reasonably changing slurry proportion and shield tail grouting construction parameters, and the safe and rapid construction of shield tail grouting is ensured.
Compared with the prior art, the invention has the beneficial effects that: different from the previous scholars' study and determination of the slurry proportioning method, the slurry diffusion stage of the shield tail synchronous grouting is divided into the permeation diffusion stage and the compaction diffusion stage, and the influence of the stratum percolation effect is considered, so that a filter cake growth speed equation applicable to the stratum with smaller porosity is established, the early generation of the filter cake is helpful for ensuring that the slurry is sealed into a ring in the shield tail gap, and the slurry water-cement ratio range of the adaptation stratum is determined through a theoretical formula.
Drawings
FIG. 1 is an analysis chart of a synchronous grouting slurry diffusion mode of a shield in a water-rich fine sand layer;
FIG. 2 is a plot of slurry pressure profile of slurry in a water-rich silty sand layer;
FIG. 3 is a diagram of a process of slurry to form a filter cake on the surface of fine silt;
FIG. 4 is a schematic illustration of slurry compact diffusion;
FIG. 5 is a schematic diagram of a shield tail synchronous grouting similar model system;
FIG. 6 is a schematic diagram of a filter cake and slurry produced during the test;
FIG. 7 is a schematic diagram of an upper and lower grouting hole arrangement;
Detailed Description
The technical solutions in the examples of the present invention will be clearly and completely described below with reference to the accompanying drawings of the examples of the present invention, and it is apparent that the described examples are only some, but not all, embodiments of the present invention, which are only used to explain and illustrate the technical solutions of the present invention, and are not to be construed as limiting the technical solutions of the present invention.
Referring to fig. 1-7, a rapid construction method for generating a filter cake layer by synchronous grouting of shield tails of a water-rich fine sand layer comprises the following steps:
step 1: because the slurry is permeated and diffused in the fine sand layer, and is influenced by the percolation effect of fine sand, slurry particles can be deposited in soil layer pores and gradually deposit and jam the soil layer pores to finally form a filter cake, abundant groundwater is contained in the water-rich fine sand layer, the filter cake can prevent the groundwater from permeating into a shield tail gap after the shield tail is formed, the slurry on the inner side of the filter cake rapidly fills the shield tail gap due to the fact that the slurry is subjected to small groundwater scouring force, along with the continuous grouting time, the slurry pressure acts on the filter cake, and the filter cake converts the slurry pressure into effective stress to act on the soil layer, so that a tunnel structure is stabilized. According to the invention, the displacement effect of slurry on groundwater in soil pores is considered when the slurry diffuses in a soil layer, and a slurry diffusion equation considering the percolation effect is established; establishing a filter cake growth rate equation based on the theory of capillary groups and the law of conservation of mass;
establishing a filter cake growth rate equation includes:
preferably, based on the theory of capillary group and the law of conservation of mass, a filter cake growth rate equation formed by the permeation and diffusion of slurry in a water-rich fine sand layer is established, and the viscosity timeliness of the slurry is considered, wherein the formula parameters comprise grouting pressure, soil layer grain composition and slurry water-cement ratio, and the formula parameters comprise the following steps:
considering the displacement effect of slurry on groundwater in soil when the slurry diffuses in soil layer, and establishing a filter cake growth thickness equation considering the percolation effect based on capillary group theory:
n 0 for the initial porosity of the formation,
n is the formation porosity, determined by:
k is the initial pore radius of the formation, which can be determined by:
phi is the formation porosity, and can be determined by:
gamma is the volume weight of the soil body,
γ s is the volume weight of the soil particles,
w is the water content of the stratum;
k 1 taking the KC constant as 180;
is the initial slurry particle volume fraction;
p c the pressure at the filter cake and formation interface is determined by the following formula:
p c ＝γ w p 0 (5)；
p 0 is grouting pressure;
p a is a dimension parameter;
for the slurry-related coefficients, taken herein as-34;
τ 0 yield shear stress for the slurry;
μ 0 the initial viscosity Pa.s of the slurry;
b is a viscosity timeliness parameter of the slurry;
d 10 the diameter of the soil particles in the soil layer is corresponding to 10 percent;
d 85 the particle diameter is corresponding to 85 percent of the cement particles;
ρ c is the density g/cm of cement particles 3 ；
w/c is the water-ash ratio of the slurry;
deriving it with respect to time to obtain the filter cake growth rate equation:
the growth thickness and the growth rate of the cement filter cake can be obtained through the formula (1) and the formula (6), and the cement slurry water-cement ratio range required by grouting the shield in the water-rich fine sand layer can be preliminarily determined through comparing the change curve of the growth rate of the filter cake.
Step 2: the filter cake will hinder the flushing of the slurry by the underground water after the formation of the shield tail, achieves the effect of plugging the underground water, ensures that the slurry at the inner side of the filter cake can quickly fill the shield tail gap, and therefore, the slurry forms the filter cake earlier in the shield tail gap, which is helpful for the quick completion of grouting construction in the water-rich fine sand layer, and the construction parameters and the slurry proportioning range can be determined according to the filter cake generation theoretical equation in claim 1 in practical engineering.
Step 3: aiming at a filter cake generation rate equation, the cement slurry water-cement ratio suitable for the water-rich fine sand layer is provided, the water-cement ratio is controlled to be 0.7-0.8 for the fine sand layer with the porosity of 0.38, and the novel slurry with water-dispersion resistance is prepared through an indoor response surface test:
table 1 novel slurry formulation
Step 4: according to the change rule of the growth rate curve of the filter cake, for the fine sand layer with the porosity of 0.38, slurry with the water-cement ratio of 0.7-0.8 is determined, and the grouting pressure is controlled to be 0.4Mpa in the actual grouting process, so that the quick generation of the filter cake can be ensured; 5-6, grouting construction parameters are further optimized by changing grouting working conditions of the shield tail, wherein grouting pressure is 0.4Mpa, grouting rate is 180%, grouting quantity ratio of upper grouting holes to lower grouting holes is 1.5:1, and shield tunneling speed of a shield tunneling machine is 40-50 mm/min, so that shield grouting construction of a water-rich fine sand layer can be completed rapidly.
In the actual grouting construction process, slurry at the upper part of the grouting pipe flows to the bottom of the shield tail gap under the influence of slurry dead weight, so that slurry at the top of the shield tail gap is unevenly filled, and a larger sedimentation value is generated on the ground surface.
After the ratio of the grouting amounts of the upper grouting hole to the lower grouting hole is determined, preferably, the optimal position of the grouting pipe is deduced through the grouting amount required by the shield tail gap, so that the slurry is fully filled in the shield tail gap.
Knowing the grouting amount further determines the grouting pipe position, which can be determined by the following formula:
wherein Q is the grouting amount required by a ring segment;
R 2 the distance between the shield shell and the center of the tunnel is set;
R 1 is the outer diameter of the duct piece;
l s is a ring segment length;
θ is the central angle corresponding to the grouting influence range of the grouting pipe;
the relation between the upper grouting hole and the lower grouting hole can be obtained by the optimal grouting amount ratio of the upper grouting hole and the lower grouting hole determined in the test process:
from Q 1 /Q 2 =1.5 derived: θ 1 /θ 2 ＝1.5；
And theta 1 +θ 2 =pi, further yielding:
in practice, the upper grouting pipe can be properly arranged near the top of the shield tail clearance, so that slurry can be diffused at the top of the shield tail clearance to form a filter cake to block water in time, as shown in fig. 7, which is a schematic diagram of the arrangement of upper and lower grouting holes, and can be obtained from the diagram, when the arrangement of the upper grouting holes is completed, the theta can be obtained 1 According to theta 1 And theta 2 And the relation between the positions of the lower grouting holes is determined, so that the smooth proceeding of the construction process is ensured.
By combining fig. 1 to 6 and formulas (1) and (6), it can be seen that the filter cake growth equation is related to slurry properties (water cement ratio), so that the theoretical formula of the invention can determine that the slurry cement ratio range is required when the shield is used for grouting in stratum with different porosities, and the rapid construction method for generating the filter cake layer by synchronous grouting of the shield tail of the water-rich fine sand layer is realized by analyzing the thickness and rate change curve of the filter cake by the formulas (1) and (6), preliminarily determining the suitability slurry cement ratio range and reasonable grouting pressure setting value of a certain porosity soil layer, determining the novel slurry ratio by an indoor response surface test, and further ensuring that the slurry can form a filter cake hoop at the shield tail quickly, determining grouting construction parameters by a shield tail grouting similar model test, ensuring that the slurry can fill the shield tail clearance quickly in the water-rich fine sand stratum, and ensuring that the follow-up slurry can fill the support tunnel tail clearance timely.
The above is an example of the present invention, but it is not limited to the modes of operation listed in the specification and the embodiments, and it is fully applicable to various fields suitable for the present invention, and further modifications thereof can be easily realized by those skilled in the art. Therefore, the invention is not to be limited to the specific details and illustrations shown and described herein, and all are intended to be included within the scope of the invention as defined by the following claims and their equivalents.
Claims (4)
1. A rapid construction method for generating a filter cake layer by synchronous grouting of shield tails of a water-rich fine sand layer is characterized by comprising the following steps of: considering the displacement effect of slurry on groundwater in soil when the slurry diffuses in soil, establishing a slurry diffusion equation considering the percolation effect, and deducing a filter cake growth rate equation in the grouting process of the water-rich powder fine sand layer based on capillary theory, mass conservation law and momentum conservation law:
wherein n is 0 Is the initial porosity of the stratum, n is the porosity of the stratum, k is the initial pore radius of the stratum, phi is the porosity of the stratum, gamma is the volume weight of the soil body, gamma s Is the volume weight of soil particles, w is the water content of stratum，For the initial slurry particle volume fraction, p c To the pressure at the junction of the filter cake and the stratum, p 0 For grouting pressure, p a As dimensional parameters τ 0 Yield shear stress of slurry, mu 0 The initial viscosity of the slurry, B is the aging parameter of the viscosity of the slurry, d 10 The diameter d of the soil particles corresponding to the proportion of 10% in the soil layer 85 Is the particle diameter ρ corresponding to 85% of the cement particles c The density of cement particles is given, and w/c is the water-cement ratio of the slurry.
2. The rapid construction method for generating a filter cake layer by synchronous grouting of the shield tails of a water-rich fine sand layer as claimed in claim 1, wherein the water-rich fine sand layer is a typical porous medium, and is extremely easy to generate a percolation effect when grouting is carried out in the injected medium, namely, slurry particles are diffused in stratum pores and can be subjected to adsorption and interception effects of stratum pores, so that slurry particles deposited in the pores and crowded with slurry are firstly permeated and diffused in stratum pores in the shield tails, and are influenced by the percolation effect, slurry particles generate a filter cake on the surface of a soil layer after the soil layer pores are filled and blocked by slurry particles, and the slurry pressure acts on the filter cake and converts the slurry pressure into an effective stress to act on the soil layer through the filter cake along with the continuous grouting process, and the slurry enters a compaction and diffusion stage; therefore, the diffusion mode of the shield tail synchronous grouting slurry in the soil layer can be divided into permeation diffusion and compaction diffusion, and the slurry at the inner side of the filter cake can rapidly fill the shield tail gap by enabling the filter cake to be generated on the surface of the soil layer as soon as possible, so that the safe, stable and rapid construction process is ensured.
3. The rapid construction method for generating a filter cake layer by synchronous grouting of the shield tail of a water-rich fine sand layer according to claim 1, further comprising the steps of determining the grain composition, density, permeability coefficient and porosity of fine sand through an indoor test, substituting each physical parameter of the fine sand into a filter cake growth rate equation according to claim 1, comparing the change rule of the filter cake growth rate under different water-cement ratios according to the filter cake growth rate equation of different physical property strata, controlling the water-cement ratio of the fine sand layer with the porosity of 0.38 to be 0.7-0.8 so as to ensure the smooth operation of the novel construction method, and preparing the novel slurry with water-resistant dispersibility through an indoor response surface test, wherein the water-cement ratio is 0.72, the cement-sand ratio is 0.80, the fly ash mixing amount is 5%, the bentonite mixing amount is 14.94% and the hydroxyethyl cellulose mixing amount is 0.9%, so as to ensure the smooth operation of the novel construction method.
4. The rapid construction method for generating a filter cake layer by synchronous grouting of a shield tail of a water-rich fine sand layer according to claim 1 is characterized in that grouting pressure of construction parameters of shield tail grouting is substituted into a filter cake growth rate equation according to claim 1 to compare change rules of filter cake growth rate curves under different grouting pressures, for slurry with a water cement ratio of 0.8-0.9 of the fine sand layer with a porosity of 0.38, the grouting pressure is controlled at 0.4MPa, rapid generation of the filter cake can be ensured, a test system of a similar model of synchronous grouting of the shield tail is automatically developed, the grouting pressure is controlled at 0.4MPa, the grouting rate is 180%, the tunneling speed of a shield machine is controlled at 40-50 mm/min, the grouting quantity ratio of an upper grouting hole to a lower grouting hole is 1.5:1, and the relation of the grouting hole positions of the upper grouting hole to the lower grouting hole is theta Upper part ：θ Lower part(s) =3pi/10: the surface settlement is minimum at pi/5.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211580952.6A CN116517583A (en) | 2022-12-09 | 2022-12-09 | Construction method for generating filter cake by grouting shield tail of water-rich powder fine sand layer and filling shield tail gap |
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| CN202211580952.6A CN116517583A (en) | 2022-12-09 | 2022-12-09 | Construction method for generating filter cake by grouting shield tail of water-rich powder fine sand layer and filling shield tail gap |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116732979A (en) * | 2023-08-11 | 2023-09-12 | 中冶成都勘察研究总院有限公司 | Method for treating deep red layer backfill soil foundation by using grouting steel pipe pile |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116732979A (en) * | 2023-08-11 | 2023-09-12 | 中冶成都勘察研究总院有限公司 | Method for treating deep red layer backfill soil foundation by using grouting steel pipe pile |
| CN116732979B (en) * | 2023-08-11 | 2023-10-20 | 中冶成都勘察研究总院有限公司 | Method for treating deep red layer backfill soil foundation by using grouting steel pipe pile |
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