Construction method for manufacturing shield synchronous grouting slag slurry by utilizing shield muck

Abstract

The invention relates to the field of shield tunnel design and construction, and discloses a construction method for manufacturing shield synchronous grouting slag slurry by using shield muck, which comprises the following steps: 1) field test and performance determination; (2) muck slurry is mixed and prepared; 3) preparing finished product slurry; and 4) synchronous grouting. Compared with the prior art, the synchronous grouting material has the advantages that the cost of the synchronous grouting material is obviously reduced; the problem that muck is difficult to treat in the shield tunneling process is effectively solved, reutilization of resources is achieved, and remarkable environmental protection benefits are achieved; the prepared novel composite synchronous slag slurry for the shield has good workability and flowability, building gaps in the shield construction process can be fully filled, and the stability and bearing capacity of a tunnel are improved; preparation of slag slurry and cement mortar can be switched at any time, and normal tunneling of a shield is not affected.

Description

Technical Field

[0001] The invention relates to the field of shield tunnel design and construction, in particular to a construction method for manufacturing shield synchronous grouting slurry by utilizing shield slag. Background Art

[0002] In the construction of transportation, water conservancy projects, and municipal engineering, shield construction is a commonly used tunnel excavation method, and it occupies an increasingly large market share. The traditional shield excavation normal section synchronous grouting currently mainly uses cement, lime, fly ash, sand, bentonite, etc. and water to prepare cement mortar and then grouting. The steps are as follows:

[0003] 1. Before each ring starts to advance, mix enough slurry for one ring according to the mix ratio and inject it into the grouting tank. When excavation begins, ensure that the slurry stored in the grouting tank can meet the requirements of synchronous grouting to ensure the continuity of construction.

[0004] 2. Strictly control the synchronous grouting volume and slurry quality, timely fill the building gaps through synchronous grouting, and reduce the deformation of the soil during construction. Do a good job in ground deformation and surface monitoring and analysis, and adjust the grouting volume in time.

[0005] 3. The grouting pressure should be properly controlled to fill rather than split. If the grouting pressure is too high, the soil layer outside the segment will be disturbed by the slurry, causing a large settlement and easily causing slurry leakage. At the same time, if the grouting pressure is too low, the filling speed is too slow, and the filling is insufficient, which will also increase the deformation.

[0006] 4. After the segment is out of the shield tail for 5 rings, secondary grouting is carried out behind the wall for the building gap of the segment. Grouting is carried out every 5 rings in the entire interval, and the grouting amount is controlled according to the deformation information.

[0007] Cement mortar shield synchronous grouting has formed a complete system. Since the mortar synchronous grouting liquid uses a large variety of raw materials, the corresponding grouting equipment required is relatively large and occupies a large area. Shield slag is mainly discarded, with high discard costs and large pollution. The present invention uses shield slag as the main raw material, adds a small amount of cement and admixtures to configure synchronous grouting slurry with similar performance to synchronous grouting mortar, which is particularly important for cost management, environmental protection, resource utilization and sustainable development in the field of engineering construction. Summary of the invention

[0008] The present invention aims to provide a construction method for manufacturing shield synchronous grouting slurry using shield slag, which requires that the synchronous grouting slurry produced by the shield can adapt to the grouting system of the shield machine and has the following two common control indicators: the consistency is basically 150-170mm, the initial setting time is 5-6h, and the longest can reach 10h. This method can effectively utilize shield slag, reduce the cost of synchronous grouting materials, improve economic benefits, and solve the problem of difficult slag treatment and environmental protection in cities.

[0009] A construction method for manufacturing shield synchronous grouting slurry by using shield slag, specifically comprising the following steps:

[0010] 1) On-site test and performance measurement: various performance indicators of earth pressure shield slag are measured in the on-site laboratory, and the slurry mix ratio test of slag is carried out synchronously to determine the best slurry formula;

[0011] 2) Mixing and preparation of slag slurry: Use a slag crusher to crush the earth pressure shield slag, use a screening machine to screen the crushed slag, and then use an intelligent centralized slurry station to mix it evenly to obtain a semi-finished product of the shield new composite synchronous slurry;

[0012] 3) Preparation of finished slurry: After mixing the semi-finished slurry, add cement and admixtures, and mix them evenly in the intelligent centralized slurry making station according to the mix ratio to obtain the finished shield new composite synchronous slurry;

[0013] 4) Synchronous grouting: The finished slurry is pumped into a slurry storage tank for standby use, and then transported to the synchronous grouting equipment by a rail transport vehicle, and the synchronous grouting slurry is poured during the shield tunnel construction.

[0014] As a preferred embodiment, the performance index determination in step 1) includes determining the moisture content, particle grading, plasticity index, and organic matter content of the earth pressure shield slag, and determining the sand content, slurry specific gravity, and pH value of the semi-finished slurry.

[0015] As a preferred solution, the semi-finished product slurry has a sand content of 25% to 45% and a specific gravity of 1.45 to 1.5 g / cm 3 .

[0016] As a preferred solution, the specific gravity of the finished slurry in step 3) is 1.55-1.65 g / cm 3 , consistency of 150~170mm.

[0017] As a preferred solution, in step 2), the slag crusher is an impact crusher, and the screening machine is a vibrating screening machine.

[0018] As a preferred solution, the cement added in step 3) is ordinary Portland cement, and the admixtures include suspending agent, water reducing agent, accelerating setting agent and expanding agent.

[0019] As a preferred solution, in the step 4), during the grouting construction, the grouting material is filled into the gap behind the shield tail, and after it solidifies and hardens, a hole is opened to check the fullness of the shield segment wall and the slurry coagulation to ensure the grouting quality.

[0020] As a preferred solution, during the grouting construction operation, the grouting parameters are monitored in real time and adjusted in time, and the grouting parameters include grouting pressure, grouting speed, and grouting volume.

[0021] Compared with the prior art, the advantages of the present invention are as follows: shield slag is used as raw material to make semi-finished slag slurry for storage, and then improved by adding cement and admixtures, which can reduce the cost of synchronous grouting materials by 60% to 42% compared with cement mortar; the problem of difficult slag treatment during the shield process is effectively solved; the recycling of waste is achieved, the project is more sustainable, and has significant environmental benefits; the prepared new composite synchronous slag slurry for shield has a stone rate of more than 98%, a consistency of 150 to 170 mm, good workability and fluidity, can fully fill the building gaps during the shield construction process, and improve the stability and bearing capacity of the tunnel; only slag crushing and slurry making equipment needs to be added on the ground, and the original slurry conveying system and shield tunnel grouting system do not need to be modified, and the preparation of slag slurry and cement mortar can be switched at any time without affecting the normal excavation of the shield. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention is a flow chart of the construction method of composite synchronous slag slurry for shield construction. DETAILED DESCRIPTION

[0023] In order to facilitate the understanding of the present invention by those skilled in the art, the technical solutions in the above invention content of this application will be further described and demonstrated in the form of specific implementation schemes. The following embodiments are only practical examples used to illustrate and explain the contents of the technical solutions in the specification, and should not limit the scope of the claims to be protected by this application. All technical products based on the technical solutions described in the invention content of this application should be included in the scope to be protected by this application.

[0024] A construction method for manufacturing shield synchronous grouting slurry by using shield slag, specifically comprising the following steps:

[0025] 1) On-site test and performance measurement: various performance indicators of earth pressure shield slag are measured in the on-site laboratory, and the slurry mix ratio test of the slag is carried out synchronously to determine the best slurry formula; the performance indicator measurement includes the measurement of the specific gravity, sand content, mud content, water content, particle grading, plasticity index, and organic matter content of the earth pressure shield slag, and the measurement of the sand content, slurry specific gravity, pH value, and viscosity index after the slag slurry is configured;

[0026] Determine the appropriate slag slurry sand content of 20-45%, the maximum particle size <3mm, slurry specific gravity of 1.45-1.5g / cm 3 , viscosity is 25~28pa.s;

[0027] 2) Mixing and preparation of slag slurry: Use an excavator or loader to put shield slag into the crusher feed port. After crushing with an impact crusher, it can be automatically fed to the clay slurry machine of the submersible pump connected to the water level controller through a belt conveyor according to the set weight. The mixed slurry after forced mixing and crushing is screened again with a vibrating screening machine. After removing particles larger than 3 mm, the semi-finished shield new composite synchronous slurry is obtained and stored in the slurry pool for standby use;

[0028] 3) Preparation of finished slurry: After the semi-finished slurry is stored, it is pumped into a high-speed slurry making system with weighing and metering by a slurry pump, and then ordinary Portland cement, suspending agent, accelerating setting agent, expanding agent, etc. are added according to the mix ratio, and stirred evenly to obtain the finished product of the new composite synchronous grouting slurry for shield tunneling;

[0029] 4) Synchronous grouting: The finished slurry is pumped into a slurry storage tank for standby use, and then transported to the synchronous grouting equipment originally configured by the shield machine by a rail transport vehicle, and synchronous grouting slurry is poured during the shield tunnel construction;

[0030] During the grouting construction process, the grouting material is filled into the gap behind the shield tail. After it solidifies and hardens, the fullness of the shield segment wall and the slurry coagulation are checked by opening holes to ensure the grouting quality.

[0031] During the grouting operation, the grouting parameters are monitored in real time and adjusted in time. The grouting parameters include the grouting pressure being controlled at 0.3-0.4 MPa, the grouting speed being matched with the shield tunneling speed, and the grouting amount being based on the cutterhead excavation diameter and the outer diameter of the segment. The grouting amount of each ring of the segment can be calculated according to V=Π / 4KL(D1-D2).

[0032] Where V: ring grouting volume (m 3 ), L: ring width (m), D1: excavation diameter (m), D2: segment outer diameter (m), K: expansion coefficient, take 1.3~1.5.

[0033] In the specific implementation of the present invention, a test section is selected for testing (according to the geological profile, the rock properties of the shield excavation strata in this section are determined, and the slurry parameters suitable for mixing synchronous grouting slag slurry are determined), and the slag soil is sampled on site for indoor testing;

[0034] The optimal slurry formula is tested indoors in the laboratory in three stages: in the first stage, the density, consistency, water bleeding rate, shrinkage rate, pH value and other tests are carried out on the preliminary slurry formula to determine the slurry formula; direct shear test and consolidation compression test are carried out on the selected slurry formula to determine the cohesion, internal friction angle, compression coefficient and compression modulus of the slurry material; compressive strength tests are carried out at different ages such as 3d, 7d, and 28d to determine the strength of the slurry at different ages.

[0035] In the second stage, admixtures are added to the grouting slurry formula, and various technical indicators are tested and determined; technical and economic analysis is conducted to recommend a low-cost and high-quality slurry formula (the main performance indicators of synchronous grouting slurry are controlled: the sand content of the mortar after crushing, screening and stirring by the slurry making system is 30-35%, and the specific gravity of the shield mud is 1.45-1.5g / cm 3 ).

[0036] In the third stage, the recommended formula is further studied. Direct shear test and consolidation compression test are carried out again to determine the cohesion, internal friction angle, compression coefficient and compression modulus. On the basis of conventional tests, dynamic triaxial test is carried out to examine the dynamic mechanical properties of the slurry. The durability of the recommended formula of grouting material is predicted by immersion test. The effect of formula fluctuation on the performance of synchronous grouting slurry is tested by orthogonal method.

[0037] Through the above three stages, the best slurry formula is obtained as follows: slag slurry: cement: accelerator: admixture

[0038] =1200:180~240:3~7:2~5, the performance is as follows: initial setting time is controlled at 3~6h, which can be adjusted to 10h at most according to the transportation distance; 3d unconfined compressive strength>0.5MPa, 28d compressive strength>2.5MPa; specific gravity 1.55~1.65g / cm 3 ; Initial consistency is 155-170mm, and the lowest injectable consistency is 80mm; The slurry stone rate is >98%.

[0039] On-site slurry mixing: hardening is carried out at the site next to the earth pressure shield slag pit, and 30 to 50 m3 of slurry can be stored during construction. 3The slurry pool of the slag slurry, arrange the slurry making system next to the slag pit, use excavators or loaders to transport the slag, store the slurry after slurry making, and then transport the slurry to the high-speed mixer through a slurry pump, add cement, mix it into paste, and then store it in the slurry truck at the wellhead. Due to the complexity of on-site construction, synchronous grouting construction needs to be based on indoor tests, and the construction conditions and materials of the project site need to be used for trial mixing of slurry, and adjustments should be made according to the trial mixing results. In the in-depth construction process, the grouting effect may still be weakened due to changes in the stratum and construction conditions. It is necessary to carry out improved tests according to the specific conditions of the site to improve the effect of synchronous grouting. The slurry preparation process during construction is: first, add water to the mixing drum according to the ratio, then weigh the materials according to the mix ratio and add them to the mixing drum, then start the mixer to stir, inject the slurry into the slurry storage drum, and send the slurry into the tunnel for synchronous grouting. Finally, check the grouting construction effect.

[0040] If it fails, re-mix.

[0041] Production test stage: According to the test data after indoor test and on-site slurry mixing, further production test is applied to the current stage of low mix strength. It is planned to adjust the mix ratio, mainly the amount of cement and admixtures in the mix ratio, to improve the strength, and conduct physical engineering application tests at the same time, and dynamically adjust according to the usage during the process. (The main control indicators of the synchronous grouting slurry in the production test stage are: consistency: 150~170mm. Specific gravity: 1.55~1.65g / cm 3 ).

[0042] Storage and transportation of synchronous grouting slurry: After the indoor test and production test mix ratio adjustment are completed, the tunnel synchronous grouting is carried out on a 300-ring tunnel actual application test section. The slurry is pumped to the horizontal transport slurry truck using a slurry pump. Each train is equipped with a 15-cubic-meter mortar truck, which is transported to the trolley and synchronous grouting is carried out through the shield machine's synchronous grouting system.

[0043] A construction method for using shield slag to make shield synchronous grouting slurry was developed. The posture of the test section segments was manually remeasured. The maximum vertical deviation of the 300-ring shield tunnel was 33mm, mainly concentrated in the range of ±20mm. The floating amount of the segments was small and the overall stability was achieved.

[0044] The maximum cumulative change of surface settlement in the test section is -2.59mm, and the maximum change this time is -0.74mm; the maximum cumulative change of horizontal displacement of segment lining in the test section is -1.1mm, and the maximum change this time is -0.9mm; the maximum cumulative change of vertical displacement of segment lining in the test section is 0.9mm, and the maximum change this time is -0.7mm; the maximum cumulative change of clearance convergence of segment lining is 1.1mm, and the maximum change this time is -0.4mm; there is no abnormality in the monitoring data, and the changes in monitoring data are similar to those in the normal excavation section, with no obvious differences.

[0045] The hole was opened to check the fullness of the wall and the slurry coagulation. There was a small amount of water dripping behind the wall of the segment, but no air. It was initially judged that the slurry could coagulate behind the wall of the segment and fill it up. The radar scan of the wall of the segment in the slurry area was carried out, and the scanning results showed that the wall of the segment was full.

[0046] By checking for leakage on the test section segments, it was found that there was almost no leakage, which is better than the simultaneous grouting with cement mortar.

[0047] The invention discloses a construction method for manufacturing shield synchronous grouting slurry by using shield slag, which can solve the problem of processing some slag in shield tunnel construction, fully recycle resources in terms of environmental protection, and achieve the goal of turning waste into treasure. By adding admixtures for improvement, a complete set of slurry mechanized mixing equipment is operated in a flow line, and finally the purpose of reducing production costs, improving the linearity of shield interval tunnels and reducing leakage rates is achieved.

[0048] The present invention and its implementation methods and test results are described above, and such description is not restrictive. The drawings show only one implementation method of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can creatively design a structure and embodiment similar to the technical solution, which should fall within the protection scope of the present invention.

Claims

1. A construction method for manufacturing shield synchronous grouting slurry using shield slag, specifically comprising the following steps: 1) On-site test and performance measurement: The performance index of shield slag is measured in the on-site laboratory, and the slurry mix ratio test of synchronous grouting slag is carried out to determine the best slurry formula; 2) Mixing and preparation of semi-finished slurry: Use a screening crusher to crush and screen the shield slag, weigh the usable material and send it to the mud slurry making machine to make slag slurry, and then use a screening machine for secondary screening. After removing the coarse particles, the slurry performance is measured in the buffer tank. When it meets the requirements, the semi-finished shield synchronous grouting liquid is obtained and stored in the semi-finished slurry pool; 3) Preparation of finished slurry: After the semi-finished slurry is injected into the intelligent slurry making system by a slurry pump, cement, admixtures, etc. are added according to the mix ratio and stirred evenly to obtain the finished slurry slurry for shield synchronous grouting; 4) Synchronous grouting: The finished slurry is pumped to a slurry truck for standby use, and then transported to the synchronous grouting position of the shield machine by a rail transport vehicle. The synchronous grouting is carried out using the original grouting system configured on the shield machine.

2. A construction method for manufacturing shield synchronous grouting slurry using shield slag according to claim 1, characterized in that: The performance index determination in step 1) includes determining the water content, particle grading, plasticity index and organic matter content of the earth pressure shield slag, and determining the sand content, viscosity, specific gravity and pH value of the semi-finished slurry, and determining the consistency, specific gravity, initial setting and final setting time, stone rate and other indicators of the finished slurry.

3. A construction method for manufacturing shield synchronous grouting slurry using shield slag according to claim 2, characterized in that: The semi-finished product slurry has a sand content of 25% to 45% and a specific gravity of 1.45 to 1.5 g / cm 3 .

4. The construction method for manufacturing shield synchronous grouting slurry by using shield slag according to claim 1, characterized in that: The specific gravity of the finished slurry in step 3) is 1.55-1.65 g / cm 3 , consistency of 150~170mm.

5. The construction method for manufacturing shield synchronous grouting slurry by using shield slag according to claim 1, characterized in that: In the step 2), the soil crusher is an impact crusher, and the screening machine is a vibrating screening machine.

6. The construction method for manufacturing shield synchronous grouting slurry by using shield slag according to claim 1, characterized in that: The cement added in step 3) is ordinary Portland cement, and the admixtures include suspending agent, water reducing agent, thickening agent, accelerating setting agent and expanding agent.

7. The construction method for manufacturing shield synchronous grouting fluid using shield slag according to claim 1, characterized in that: In the step 4), during the grouting construction, the grouting material is filled into the gap behind the shield tail, and after it is solidified, a hole is opened to check the fullness of the shield segment wall and the slurry coagulation to ensure the grouting quality.

8. The construction method for manufacturing shield synchronous grouting slurry by using shield slag according to claim 7, characterized in that: During the grouting operation, the original grouting system of the shield machine is fully utilized. According to the shield excavation parameters and tunnel parameters, the grouting parameters including grouting pressure, grouting speed, grouting volume, etc. are monitored in real time and adjusted in time.

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