A method for processing soil arching and stagnation in the soil bin of an earth pressure balance shield machine without opening the bin

Abstract

A method for treating the arching and stagnant discharge of slag in the soil bin of an earth pressure balance shield machine without opening the bin. First, grouting is used to form a closed space at the arching part of the spiral machine in the bin. Then, clay-like bentonite is pumped into the bin. The pressure is controlled during the pumping process. If the pressure in the bin is too high, the clay-like bentonite is stopped. The cutterhead is then rotated to restore the bin pressure to normal. The cutterhead is stopped and the clay-like bentonite is resumed. This cycle is repeated until the arching part of the spiral machine is destroyed. This method can effectively solve the problem of abnormal arching and slag discharge in the spiral machine. It has the characteristics of high arch breaking efficiency, short cycle, low construction cost, and easy operation. In addition, this method can not only ensure that the ground does not rise during the treatment process, reducing the impact on the surrounding environment, but also avoid the safety risks of manual bin opening and clearing, thereby improving construction safety.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnel construction, and in particular to a method for processing the arching of a screw machine in a soil bin of an earth pressure balance shield machine in complex strata. Background Art

[0002] Shield construction is suitable for various geological conditions and has the advantages of fast construction speed, high construction efficiency, small impact on construction safety and small environmental impact. More and more tunnels are widely used in shield construction.

[0003] When tunneling in complex strata, Earth Pressure Balance (EPB) shields often fail to remove large debris from the bottom of the soil bin through the screw conveyor in a timely manner. This large amount of debris accumulates in the soil bin and gradually forms an arch at the top of the screw conveyor's inlet. This arch prevents the soil from falling smoothly during the screw conveyor's discharge, leading to abnormal screw discharge and crushing of the cutterhead, significantly impacting the shield machine's tunneling efficiency.

[0004] The existing methods for dealing with soil arches in shield soil bins include the following three: 1. The screw machine reverse back pressure method breaks the stone arch in the bin by extending and retracting the screw machine; 2. The bin clearing method is to clear the debris in the bin after opening the bin, and then manually destroy the stone arch after clearing it to the top of the screw machine; 3. The bin water injection method is to connect the water source through the reserved hole at the bottom of the screw machine and inject water to destroy the stone arch.

[0005] However, the above treatment methods cannot deal with the soil arch in the warehouse in a timely and effective manner. The reverse pressure of the spiral machine is poor and inefficient in breaking the arch. It requires multiple spiral machine reversals and cannot effectively break the stone arch. The warehouse clearance treatment method has many auxiliary measures, is time-consuming, costly, inefficient, and has a high safety risk for personnel entering the warehouse. The water injection method is difficult to control the pressure in the warehouse, which can easily cause the pressure in the warehouse to increase, leading to ground uplift, pipeline damage and other social impacts. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a method for treating the arching and stagnant discharge of slag in the soil bin of an earth pressure balance shield machine without opening the bin. The method has the characteristics of easy operation, good effect, high efficiency, low safety risk and little impact on the surrounding environment.

[0007] In order to achieve the above-mentioned object, the technical solution adopted by the present invention is to provide a method for treating the arching and stagnant drainage of slag in the soil bin of an earth pressure balance shield machine without opening the bin, comprising the following steps:

[0008] 1) Construction preparation: Grouting is used to separate the gap between the soil bin and the shield, so that the arched part of the screw machine in the soil bin forms a closed space;

[0009] 2) Pumping clay: Pump clay-like bentonite into the soil bin. The pressure of the clay-like bentonite is greater than the load pressure of the arched part of the screw machine;

[0010] 3) Control pressure: If the pressure in the soil bin is too high, stop pumping the clay-like bentonite, then rotate the cutter disc until the soil bin pressure returns to normal, stop rotating the cutter disc, and resume pumping the clay-like bentonite. Repeat this cycle until the arched part of the screw machine is destroyed.

[0011] As a further improvement of the present invention, in step 1), grouting is performed using radial holes of the shield machine and grouting holes of the segments.

[0012] As a further improvement of the present invention, in step 1), grouting is performed in the radial holes of the shield in the shield machine from bottom to top, and segment grouting holes are set at the third ring segment that comes out of the shield tail for grouting. The positions of the segment grouting holes are 1 o'clock and 11 o'clock in the clock direction.

[0013] As a further improvement of the present invention, in step 2), a clay delivery pump is used to pump clay-like bentonite, and the clay-like bentonite is sodium bentonite. The sodium bentonite is stirred by a stirring system of the clay delivery pump in a ratio of sodium bentonite: water = 12 to 18:1 before being pumped.

[0014] As a further improvement of the present invention, in step 2), the ratio of sodium bentonite to water is 15:1.

[0015] As a further improvement of the present invention, in step 2), a reserved hole is provided at the bottom of the screw machine, and the clay-like bentonite is pumped through the reserved hole at the bottom of the screw machine.

[0016] As a further improvement of the present invention, in step 2), the pumping pressure of the clay-like bentonite is controlled to be 0.4-0.5 MPa.

[0017] As a further improvement of the present invention, in step 3), excessive soil bin pressure means that the soil bin pressure exceeds 2.5 bar, and returning to normal soil bin pressure means that the soil bin pressure is lower than 2.0 bar.

[0018] As a further improvement of the present invention, in step 3), when the cutter disc rotates, its rotation speed is controlled to be 0.3-0.7 rpm.

[0019] As a further improvement of the present invention, in step 3), when the cutter disc rotates, its rotation speed is controlled to 0.5 rpm.

[0020] The beneficial effects of the present invention are as follows: the method forms an enclosed space in the soil bin by grouting, and then locally pressurizes the soil bin by pumping clay-like bentonite in the enclosed space, and then destroys the arched part by rotating the cutter disc, thereby effectively solving the problem of abnormal arching and slag discharge of the spiral machine. It has the characteristics of high arch breaking efficiency, short cycle, low construction cost and easy operation. In addition, this method can not only ensure that the ground does not rise during the treatment process, reducing the impact on the surrounding environment, but also does not require opening the bin for construction, can avoid the safety risks of manual opening and clearing of the bin, and improve construction safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the construction structure of the method of the present invention;

[0022] Markings: Soil bin 1, screw conveyor 2, arching part 3, confined space 4, radial hole in the middle shield 5, grouting hole in the segment 6, clay delivery pump 7, cutterhead 8 DETAILED DESCRIPTION

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figure 1 As shown, a method for processing the arching and stagnant drainage of slag in the earth bunker of an earth pressure balance shield machine without opening the bunker includes the following steps:

[0025] 1) Construction preparation: Use grouting to isolate the gap between the soil bin 1 and the shield. Specifically, when the top of the earth pressure balance shield machine's screw machine 2 is arched, grouting is performed from bottom to top through the shield machine's middle shield radial holes 5. At the same time, segment grouting holes 6 are set at the third ring segment that has emerged from the shield tail for grouting. The segments grouting holes 6 are located at 1 o'clock and 11 o'clock in the clock direction. After the grouting is completed, the machine is shut down for 5 hours to achieve the strength of the slurry, and the effect of the secondary grouting is checked, with "no obvious water stains" as the standard. The above-mentioned double grouting is used to isolate the gap between the soil bin 1 and the shield, so that the arched part 3 of the screw machine 2 in the soil bin 1 forms a closed space 4.

[0026] 2) Pumping Clay: Clay-like bentonite is pumped into the soil bin 1. The pressure of the clay-like bentonite is greater than the load pressure of the arched portion 3 of the screw conveyor 2. Specifically, a 7.5 kW clay delivery pump 7 is used to pump the clay-like bentonite. The clay-like bentonite is sodium-based bentonite. The sodium-based bentonite is stirred by the stirring system of the clay delivery pump 7 at a ratio of sodium-based bentonite:water = 12-18:1 until it becomes viscous before being pumped. In this embodiment, the ratio of sodium-based bentonite:water = 15:1. The bottom of the screw conveyor 2 is provided with a reserved hole, through which the clay-like bentonite is pumped into the sealed soil bin 1. The pumping pressure is controlled at 0.4-0.5 MPa. The clay-like bentonite is pumped to locally increase the pressure of the arched portion 3 of the screw machine 2 in the soil bin 1. The pressure of the clay-like bentonite is made greater than the load pressure of the arched portion 3 at the top of the screw machine 2, thereby destroying the stone arch at the arched portion 3.

[0027] 3) Pressure Control: While injecting clay-like bentonite into the pre-installed hole in the screw conveyor 2, observe changes in soil pressure in the soil chamber 1 and maintain the pressure at 2.5 bar. If the pressure in the soil chamber 1 is excessive, i.e., exceeds 2.5 bar, stop pumping the clay-like bentonite and rotate the cutterhead 8. The cutterhead 8 speed is controlled to 0.3-0.7 rpm. In this embodiment, the cutterhead 8 speed is controlled to 0.5 rpm. After the cutterhead 8 rotates for 20 minutes, observe changes in soil pressure. When the pressure in the soil chamber 1 returns to normal, i.e., below 2.0 bar, stop rotating the cutterhead 8 and resume pumping the clay-like bentonite. Repeat this cycle until the arched portion 3 of the screw conveyor 2 is destroyed.

[0028] After completing all the above steps, the clay pump 7 uses pressure to break the stone arch at the arching portion 3 of the screw conveyor 2 in the soil bin 1. The screw conveyor 2 can then discharge the slag smoothly, eliminating the need for manual opening of the bin at normal pressure to break the stone arch. This method is characterized by easy operation, good treatment results, and high construction efficiency, effectively shortening the construction period and reducing construction costs. By rotating the cutterhead 8 to reduce local pressure, this method can minimize the impact on the surrounding environment and reduce safety risks.

[0029] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention in any form. Any person with ordinary knowledge in the technical field can make equivalent embodiments by making partial changes or modifications to the technical contents disclosed by the present invention without departing from the scope of the technical features of the present invention, and the equivalent embodiments still fall within the scope of the technical features of the present invention without departing from the technical features of the present invention.

Claims

1. A method for treating soil arching and stagnation in the earth bunker of an earth pressure balance shield machine without opening the bunker, characterized in that The following steps are involved: 1) Construction Preparation: Grouting is used to isolate the gap between the soil bin and the shield, forming a closed space at the arch of the screw machine inside the soil bin. Grouting is carried out using the radial holes of the shield machine and the grouting holes of the segments. Grouting is carried out in the radial holes of the shield from bottom to top. Segment grouting holes are set at the third ring of segments after they have emerged from the shield tail. The grouting holes are located at 1 and 11 o'clock. 2) Pumping clay: Clay-like bentonite is pumped into the confined space of the soil bin. The pressure of the clay-like bentonite is greater than the load pressure of the arched part of the screw conveyor. The bottom of the screw conveyor is provided with a reserved hole, through which the clay-like bentonite is pumped. The pumping pressure of the clay-like bentonite is controlled at 0.4-0.5 MPa. 3) Control pressure: If the pressure in the soil bin is too high, stop pumping the clay-like bentonite, then rotate the cutter disc until the soil bin pressure returns to normal, stop rotating the cutter disc, and resume pumping the clay-like bentonite. Repeat this cycle until the arched part of the screw machine is destroyed. When the cutter disc rotates, its speed is controlled at 0.3-0.7 rpm.

2. The method for treating soil arching and stagnation in the earth bunker of an earth pressure balance shield machine without opening the bunker according to claim 1, characterized in that: In step 2), clay-like bentonite is pumped by a clay delivery pump. The clay-like bentonite is sodium bentonite. The sodium bentonite is stirred by a stirring system of the clay delivery pump in a ratio of sodium bentonite to water of 12 to 18:1 before being pumped.

3. The method for treating soil arching and stagnation in the earth bunker of an earth pressure balance shield machine without opening the bunker according to claim 2, characterized in that: In step 2), the ratio of sodium bentonite to water is 15:

1.

4. A method for treating soil arching and stagnation in the earth bunker of an earth pressure balance shield machine without opening the bunker according to claim 1, 2 or 3, characterized in that: In step 3), excessive soil bin pressure means that the soil bin pressure exceeds 2.5 bar, and normal soil bin pressure means that the soil bin pressure is lower than 2.0 bar.

5. The method for treating soil arching and stagnation in the earth bunker of an earth pressure balance shield machine without opening the bunker according to claim 1, characterized in that: In step 3), when the cutter disc rotates, its speed is controlled to 0.5 rpm.

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