Pre-grouting system at the bottom of the communication channel and method for controlling thawing settlement after freezing construction
By setting up multiple grouting holes and grouting pipes at the bottom of the contact channel, and grouting section by section using cement-water glass double slurry, the problem of melting and sinking control after freezing construction is solved, and the uniformity of formation settlement and construction cost are achieved. The reduction.
Patent Information
- Application Number
- CN201910392423.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2019-05-13
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2039-05-13
AI Technical Summary
The existing frozen construction technology is difficult to effectively control the melting and subsidence after the contact channel construction, resulting in uneven formation settlement, affecting the safety of surrounding buildings and subway operations, and has high construction costs and long cycles.
The pre-grouting system at the bottom of the contact channel is designed to have multiple grouting holes and grouting pipes at the bottom. The grouting material is cement-water glass double slurry. Grouting is carried out through a variable speed grouting pump, following a small amount and multiple times. , multi-point and uniform principle, grouting section by section to ensure the reinforcement of the frozen area.
Effectively control the formation settlement caused by the thawing of frozen soil after freezing construction, without pre-grouting or compensation for grouting on the upper part of the contact channel and both sides, shortening the construction period and reducing costs.
Smart Images
Figure CN110130316B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of freezing construction, and relates to a method for controlling thawing settlement of a communication channel after freezing construction, in particular to a communication channel bottom pre-grouting system and a method for controlling thawing settlement after freezing construction. Background Art
[0002] Freezing reinforcement is widely used in the construction of tunnel communication channels in water-rich soft soil layers in Shanghai, Nanjing, Suzhou and other places. This method has high reinforcement strength and good water-stopping performance, but the later thawing settlement of this method is large. After the freezing construction of the communication channel is completed, the thawing period tracking grouting filling soil is generally used to control the stratum settlement. The selection of grouting locations mostly depends on engineering experience, and the grouting amount is only based on daily ground settlement monitoring. The controllability of the project is poor, and it is difficult to completely control the post-construction thawing settlement of the soft soil layer, which will cause settlement, cracking and other adverse effects on surrounding buildings; at the same time, due to the long thawing settlement period, the inadequate grouting in the early stage often leads to uneven settlement of the up and down lines during the operation of the subway, causing serious safety hazards.
[0003] In order to ensure the smooth progress of the project and the safety of the surrounding environment, before freezing the construction of some communication channels, cement slurry is first injected into the upper and lower sides and both sides of the communication channels, and then artificial freezing method construction is carried out on the already formed cement soil foundation. The frozen soil layer that has been pre-grouted has less settlement during the melting period, but the amount of cement used is large, and the labor and equipment costs are high.
[0004] One of the most critical technical issues in controlling post-thaw settlement and freezing of pre-grouting of connecting channels is the construction of pre-grouting of connecting channels. The construction method is relatively complicated and the construction cost is relatively high. The commonly used method is to inject cement slurry above and below and on both sides of the connecting channel, which can not only reinforce the soil layer but also control the thawing settlement after freezing. However, it consumes a large amount of grouting slurry, uses a large amount of equipment and manpower, and has a great impact on the pipe segments, and the construction period is long. Studies have found that the thawing settlement of connecting channels is mainly caused by the thawing settlement of the bottom area. Controlling the thawing settlement of the bottom can make the overall thawing settlement reach the allowable settlement range of the project without affecting the surrounding buildings and the later operation of the subway. Therefore, it is necessary to focus on strengthening the reinforcement of the bottom of the connecting channel during construction. Summary of the invention
[0005] Technical problem to be solved: In order to overcome the shortcomings of the prior art, a construction method is obtained that can quickly and effectively control thawing settlement after freezing work, without the need for pre-grouting on the upper part and both sides of the connecting channel, and without the need for compensatory grouting after freezing. The present invention provides a pre-grouting system for the bottom of the connecting channel and a method for controlling thawing settlement after freezing construction.
[0006] Technical solution: A pre-grouting system for the bottom of the connecting channel, wherein the system is provided with at least one row of grouting holes within the designed freezing range at the bottom of the connecting channel, and each row of grouting holes has at least one grouting hole, and grouting pipes are inserted from the grouting holes into the designed freezing range, and the angle between each row of grouting holes and the centerline of the tunnel is 10°-80°, and the angle between the grouting pipe and the centerline of the tunnel is 15°-75°.
[0007] Preferably, the grouting holes are arranged in three rows, namely the first grouting hole, the second grouting hole and the third grouting hole.
[0008] Preferably, the angle between the first grouting hole and the center line of the tunnel is 15°, the angle between the second grouting hole and the center line of the tunnel is 30°, and the angle between the third grouting hole and the center line of the tunnel is 60°.
[0009] Preferably, the ratio of the spacing between the first grouting hole and the second grouting hole to the spacing between the second grouting hole and the third grouting hole is 1:2-1:0.8.
[0010] Preferably, there are 7 grouting holes in each row, and they are arranged symmetrically along the center line of the connecting channel.
[0011] Preferably, the grouting pipes corresponding to the first grouting hole, the second grouting hole and the third grouting hole are the first grouting pipe, the second grouting pipe and the third grouting pipe, respectively, wherein the angle between the first grouting pipe and the center line of the tunnel is 45°, and the angle between the second grouting pipe and the third grouting pipe and the center line of the tunnel is 60°.
[0012] Preferably, the first grouting pipe, the second grouting pipe and the third grouting pipe are all segmented grouting pipes, and the ratio of grouting depths is 1:2:2.
[0013] The method for controlling thawing settlement after freezing construction by the pre-grouting system at the bottom of any of the above communication channels comprises the following steps:
[0014] a. Grouting hole arrangement: When the shield advances and splices the pipe segments, pipe segments with reserved grouting holes are used on both sides of the communication channel, and the left and right lines are arranged symmetrically. It is preferred to set 4 pieces on each side, for a total of 8 pieces;
[0015] b. Grouting pipe arrangement: Drill into the grouting pipe from the reserved grouting hole to carry out grouting. The grouting pipe is arranged in sections. It is preferred that the grouting pipe is Φ30×6mm, 20# low-carbon seamless steel pipe, with a length of 1m per section;
[0016] c. Grouting materials and parameters. The grouting equipment is BW250 variable speed grouting pump. The grouting slurry is mainly cement-water glass double liquid slurry, supplemented by single liquid cement slurry. The volume ratio of cement slurry and water glass solution is 3:1-4:1, of which the water-cement ratio of cement slurry is 0.7-1.25, the concentration of water glass is 20Be′-50Be′, the grouting pressure is 0.2-0.8MPa, and the grouting flow rate is controlled at 1.0-2m3 / h;
[0017] d. Grouting principles and methods: First, grout the grouting holes of the pipe segments on both sides of the bottom of the left line communication channel. After the left line is fully grouted, grout the right line. The pre-grouting follows the principle of small amount, multiple times, multiple points and uniformity. Grouting is carried out section by section according to the designed depth. When grouting, start grouting from the middle grouting hole of the first row, and then pour into the grouting holes at both ends in turn; then start grouting from the grouting holes at both ends of the second row, and then pour into the middle grouting hole in turn, and then grout from the middle grouting hole of the third row to the grouting holes at both ends;
[0018] e. Arrange freezing station, install equipment, connect pipes, insulate and test instruments, dissolve calcium chloride and fill fluorine and oil for the unit;
[0019] f. After the grouting is completed, use hydrophilic epoxy resin concrete to seal the holes and cure for 14 days. Then start the freezing construction and maintain the minimum brine temperature at -30 to -28°C until the reinforcement of the designed freezing area is completed.
[0020] Beneficial effects: (1) The pre-grouting system for the bottom of the connecting channel and the method for controlling thawing settlement after freezing construction described in the present invention can effectively control the ground settlement caused by the melting of frozen soil after freezing construction, without the need for pre-grouting on the top and both sides of the connecting channel, and without the need for compensatory grouting after freezing; (2) The system and method described in the present invention have a short construction period and low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the bottom structure of the communication channel bottom pre-grouting system of the present invention;
[0022] Figure 2 yes Figure 1 AA section view;
[0023] Figure 3 yes Figure 1 BB cross-section diagram;
[0024] Among them, 1-the first grouting hole, 2-the second grouting hole, 3-the third grouting hole, 4-the first grouting pipe, 5-the second grouting pipe, 6-the third grouting pipe, 7-the center line of the communication channel, 8-the center line of the tunnel, 9-the designed freezing range, 10-the pipe segment with reserved grouting holes. DETAILED DESCRIPTION
[0025] The following examples further illustrate the content of the present invention, but should not be construed as limiting the present invention. Without departing from the spirit and essence of the present invention, modifications and substitutions made to the method, steps or conditions of the present invention all belong to the scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.
[0026] Example 1
[0027] A pre-grouting system for the bottom of the connecting channel, wherein the system is provided with at least one row of grouting holes within the designed freezing range 9 at the bottom of the connecting channel, and each row of grouting holes has at least one grouting hole, and a grouting pipe is inserted from the grouting hole into the designed freezing range 9, and the angle between each row of grouting holes and the center line of the tunnel is 10°-80°, and the angle between the grouting pipe and the center line of the tunnel is 15°-75°.
[0028] The grouting holes are arranged in three rows, namely the first grouting hole 1, the second grouting hole 2 and the third grouting hole 3.
[0029] The angle between the first grouting hole 1 and the center line of the tunnel is 15°, the angle between the second grouting hole 2 and the center line of the tunnel is 30°, and the angle between the third grouting hole 3 and the center line of the tunnel is 60°.
[0030] The ratio of the spacing between the first grouting hole 1 and the second grouting hole 2 to the spacing between the second grouting hole 2 and the third grouting hole 3 is 1:2-1:0.8.
[0031] There are 7 grouting holes in each row, and they are arranged symmetrically along the center line 7 of the connecting channel.
[0032] The grouting pipes corresponding to the first grouting hole 1, the second grouting hole 2 and the third grouting hole 3 are the first grouting pipe 4, the second grouting pipe 5 and the third grouting pipe 6 respectively, wherein the angle between the first grouting pipe 4 and the center line of the tunnel is 45°, and the angle between the second grouting pipe 5 and the third grouting pipe 6 and the center line of the tunnel is 60°.
[0033] The first grouting pipe 4 , the second grouting pipe 5 and the third grouting pipe 6 are all segmented grouting pipes, and the ratio of grouting depths is 1:2:2.
[0034] The method for controlling thawing settlement after freezing construction by the pre-grouting system at the bottom of any of the above communication channels comprises the following steps:
[0035] a. Grouting hole arrangement: When the shield advances and splices the pipe segments, pipe segments with reserved grouting holes are used on both sides of the communication channel, and the left and right lines are arranged symmetrically. It is preferred to set 4 pieces on each side, for a total of 8 pieces;
[0036] b. Grouting pipe arrangement: Drill into the grouting pipe from the reserved grouting hole to carry out grouting. The grouting pipe is arranged in sections. It is preferred that the grouting pipe is Φ30×6mm, 20# low-carbon seamless steel pipe, with a length of 1m per section;
[0037] c. Grouting materials and parameters. The grouting equipment is BW250 variable speed grouting pump. The grouting slurry is mainly cement-water glass double liquid slurry, supplemented by single liquid cement slurry. The volume ratio of cement slurry and water glass solution is 3:1-4:1, of which the water-cement ratio of cement slurry is 0.7-1.25, the concentration of water glass is 20Be′-50Be′, the grouting pressure is 0.2-0.8MPa, and the grouting flow rate is controlled at 1.0-2m 3 / h;
[0038] d. Grouting principles and methods: First, grout the grouting holes of the pipe segments on both sides of the bottom of the left line communication channel. After the left line is fully grouted, grout the right line. The pre-grouting follows the principle of small amount, multiple times, multiple points and uniformity. Grouting is carried out section by section according to the designed depth. When grouting, start grouting from the middle grouting hole of the first row, and then pour into the grouting holes at both ends in turn; then start grouting from the grouting holes at both ends of the second row, and then pour into the middle grouting hole in turn, and then grout from the middle grouting hole of the third row to the grouting holes at both ends;
[0039] e. Arrange freezing station, install equipment, connect pipes, insulate and test instruments, dissolve calcium chloride and fill fluorine and oil for the unit;
[0040] f. After the grouting is completed, use hydrophilic epoxy resin concrete to seal the holes and cure for 14 days. Then start the freezing construction and maintain the minimum brine temperature at -30 to -28°C until the reinforcement of the designed freezing area is completed.
[0041] Example 2
[0042] The stratum of a subway communication channel in Suzhou is composed of silty clay layer, clayey silt intercalated with silty clay layer, silty sand layer, and silty clay layer from top to bottom. The stratum where the communication channel is located is silty sand layer. The buried depth of the communication channel is 14m. The reinforcement project adopts the combined reinforcement of pre-grouting at the bottom of the communication channel + horizontal freezing method. According to the designer's requirements, the reinforcement depth of the communication channel is 6m.
[0043] This project adopts the technology of pre-grouting at the bottom to control post-construction melting and settlement. The specific technical scheme is as follows:
[0044] a. Arrangement of grouting holes. When the shield advances and splices the pipe segments, pipe segments with reserved grouting holes are used on both sides of the communication channel, 4 on each side, for a total of 8. Three rows of grouting holes are set on both sides of the communication channel in the part close to the designed freezing range at the bottom of the communication channel. The first row has an angle of 15° with the center line of the tunnel, and 7 grouting holes are arranged with a spacing of 50cm; the second row has an angle of 30 degrees with the center line of the tunnel, and 7 grouting holes are arranged with a spacing of 50cm; the third row has an angle of 60° with the center line of the tunnel, and 7 grouting holes are arranged with a spacing of 50cm; the spacing between the first row and the second row is 60cm, and the spacing between the second row and the third row is 70cm.
[0045] b. Grouting pipe arrangement: drill grouting pipes into the reserved grouting holes for grouting. Φ30mm seamless steel pipe grouting pipes are used, with a length of 1m per section. The first row of grouting pipes is inserted from the grouting holes to the soil at a 45° angle, reaching the position of the designed freezing bottom range. The second and third rows of grouting pipes are both inserted from the grouting holes to the soil at a 60° angle. The design reinforcement depth of the grouting pipes arranged in the third row of grouting holes is 6m, divided into 6 sections of grouting pipes, and the grouting depth of each time is 1m, that is, segmented grouting, each time 1m of grouting pipe is inserted, and the next section of grouting pipe is inserted after the grouting is completed; the design reinforcement depth of the grouting pipes arranged in the second row of grouting holes is 6m, divided into 6 sections of grouting pipes, and segmented grouting; the design reinforcement depth of the grouting pipes arranged in the first row of grouting holes is 3m, divided into 3 sections of grouting pipes, and segmented grouting.
[0046] c. Grouting materials and parameters. The grouting equipment is a BW250 variable speed grouting pump. The grouting slurry is mainly cement-water glass double liquid slurry, supplemented by single liquid cement slurry. The volume ratio of cement slurry and water glass solution is 1:0.25, of which the water-cement ratio of cement slurry is 1:0.8, the concentration of water glass is 20Be′, the grouting pressure is 0.5MPa, and the grouting flow rate is controlled at 2m 3 / h.
[0047] d. Grouting principles and methods: First, grout the grouting holes of the pipe segments on both sides of the bottom of the left line connection channel. After the left line is fully grouted, grout the right line. Pre-grouting follows the principle of small amount, multiple times, multiple points, and uniformity. Grout each section according to the designed depth. When grouting, start grouting from the grouting hole in the middle of the first row, and then pour into the grouting holes at both ends in turn; then start grouting from the grouting holes at both ends of the second row, and then pour into the grouting holes in the middle in turn. Then grout from the grouting hole in the middle of the third row to the grouting holes at both ends.
[0048] e. Arrange freezing station, install equipment, connect pipes, insulate and test instruments, dissolve calcium chloride and fill fluorine and oil into the unit.
[0049] f. After the grouting is completed, the holes are sealed with hydrophilic epoxy resin concrete and freezing construction is started, maintaining the minimum brine temperature at -30 to -28°C until the reinforcement of the designed freezing area is completed.
[0050] Example 3
[0051] The soil layers of a subway communication channel in Changzhou are mixed fill layer, silty clay layer, silty clay layer, silty sand and clayey silt layer, silty sand layer, and silty clay layer from top to bottom. The stratum where the communication channel is located is silty sand layer. The buried depth of the communication channel is 15m. The reinforcement project adopts the combined reinforcement of pre-grouting at the bottom of the communication channel + horizontal freezing method. According to the designer's requirements, the reinforcement depth of the communication channel is 8m.
[0052] This project adopts the technology of pre-grouting at the bottom to control post-construction melting and settlement. The specific technical scheme is as follows:
[0053] a. Arrangement of grouting holes. When the shield advances and splices the pipe segments, pipe segments with reserved grouting holes are used on both sides of the communication channel, 4 on each side, for a total of 8. Three rows of grouting holes are set on both sides of the communication channel in the part close to the designed freezing range at the bottom of the communication channel. The first row is at an angle of 15° with the center line of the tunnel, with 7 grouting holes arranged at a spacing of 50cm; the second row is at an angle of 30° with the center line of the tunnel, with 7 grouting holes arranged at a spacing of 60cm; the third row is at an angle of 60° with the center line of the tunnel, with 7 grouting holes arranged at a spacing of 60cm; the spacing between the first row and the second row is 60cm, and the spacing between the second row and the third row is 60cm.
[0054] b. Grouting pipe arrangement: drill grouting pipes into the reserved grouting holes for grouting. Φ30mm seamless steel pipe grouting pipes are used, with a length of 1m per section. The first row of grouting pipes is inserted into the soil from the grouting holes at a direction of 45° to the bottom of the designed freezing range. The second and third rows of grouting pipes are inserted into the soil from the grouting holes at a direction of 60°. The design reinforcement depth of the grouting pipes arranged in the third row of grouting holes is 8m, divided into 8 sections of grouting pipes, and the grouting depth of each time is 1m, that is, segmented grouting, each time 1m of grouting pipe is inserted, and the next section of grouting pipe is inserted after the grouting is completed; the design reinforcement depth of the grouting pipes arranged in the second row of grouting holes is 8m, divided into 8 sections of grouting pipes, and segmented grouting; the design reinforcement depth of the grouting pipes arranged in the first row of grouting holes is 5m, divided into 5 sections of grouting pipes, and segmented grouting.
[0055] c. Grouting materials and parameters. The grouting equipment is a BW250 variable speed grouting pump. The grouting slurry is mainly cement-water glass double liquid slurry, supplemented by single liquid cement slurry. The volume ratio of cement slurry and water glass solution is 1:0.25, of which the water-cement ratio of cement slurry is 1:0.8, the concentration of water glass is 30Be′, the grouting pressure is 0.8MPa, and the grouting flow rate is controlled at 1.5m 3 / h.
[0056] d. Grouting principles and methods: First, grout the grouting holes of the pipe segments on both sides of the bottom of the left line connection channel. After the left line is fully grouted, grout the right line. Pre-grouting follows the principle of small amount, multiple times, multiple points, and uniformity. Grout each section according to the designed depth. When grouting, start grouting from the grouting hole in the middle of the first row, and then pour into the grouting holes at both ends in turn; then start grouting from the grouting holes at both ends of the second row, and then pour into the grouting holes in the middle in turn. Then grout from the grouting hole in the middle of the third row to the grouting holes at both ends.
[0057] e. Arrange freezing station, install equipment, connect pipes, insulate and test instruments, dissolve calcium chloride and fill fluorine and oil into the unit.
[0058] f. After the grouting is completed, the holes are sealed with hydrophilic epoxy resin concrete and freezing construction is started, maintaining the minimum brine temperature at -30 to -28°C until the reinforcement of the designed freezing area is completed.
[0059] Example 4
[0060] The soil layers of a subway communication channel in Wuxi are mixed fill layer, silty clay layer, silty sand layer, silty clay layer, silty sand layer, and silty clay layer from top to bottom. The stratum where the communication channel is located is silty clay with silty soil layer. The communication channel is buried 18m deep, with a net width of 2.50m and a net height of 2.75m. The reinforcement project adopts the combined reinforcement of pre-grouting at the bottom of the communication channel + horizontal freezing method. According to the designer's requirements, the reinforcement depth of the communication channel is 6m.
[0061] This project adopts the technology of pre-grouting at the bottom to control post-construction melting and settlement. The specific technical scheme is as follows:
[0062] a. Arrangement of grouting holes. When the shield advances and splices the pipe segments, pipe segments with reserved grouting holes are used on both sides of the communication channel, 3 pieces on each side, for a total of 6 pieces. Three rows of grouting holes are set on both sides of the communication channel in the part close to the designed freezing range at the bottom of the communication channel. The first row is at an angle of 30° with the center line of the tunnel, with 7 grouting holes arranged at a spacing of 50cm; the second row is at an angle of 45° with the center line of the tunnel, with 7 grouting holes arranged at a spacing of 50cm; the third row is at an angle of 60° with the center line of the tunnel, with 7 grouting holes arranged at a spacing of 50cm; the spacing between the first row and the second row is 80cm, and the spacing between the second row and the third row is 80cm.
[0063] b. Grouting pipe arrangement: drill grouting pipes into the reserved grouting holes for grouting. The grouting pipes are Φ30mm seamless steel pipes, with a length of 1m per section. The first row of grouting pipes are inserted into the soil from the grouting holes at a direction of 45° to the bottom of the designed freezing range. The second and third rows of grouting pipes are inserted into the soil from the grouting holes at a direction of 60°. The design reinforcement depth of the grouting pipes arranged in the third row of grouting holes is 8m, divided into 8 sections of grouting pipes, and the grouting depth of each time is 1m, that is, segmented grouting, each time 1m of grouting pipe is inserted, and the next section of grouting pipe is inserted after the grouting is completed; the design reinforcement depth of the grouting pipes arranged in the second row of grouting holes is 6m, divided into 6 sections of grouting pipes, and segmented grouting; the design reinforcement depth of the grouting pipes arranged in the first row of grouting holes is 6m, divided into 6 sections of grouting pipes, and segmented grouting.
[0064] c. Grouting materials and parameters. The grouting equipment is a BW250 variable speed grouting pump. The grouting slurry is mainly cement-water glass double liquid slurry, supplemented by single liquid cement slurry. The volume ratio of cement slurry and water glass solution is 1:0.5, of which the water-cement ratio of cement slurry is 1:1, the concentration of water glass is 50Be′, the grouting pressure is 0.3MPa, and the grouting flow rate is controlled at 1.8m 3 / h.
[0065] d. Grouting principles and methods: First, grout the grouting holes of the pipe segments on both sides of the bottom of the left line connection channel. After the left line is fully grouted, grout the right line. Pre-grouting follows the principle of small amount, multiple times, multiple points, and uniformity. Grout each section according to the designed depth. When grouting, start grouting from the grouting hole in the middle of the first row, and then pour into the grouting holes at both ends in turn; then start grouting from the grouting holes at both ends of the second row, and then pour into the grouting holes in the middle in turn. Then grout from the grouting hole in the middle of the third row to the grouting holes at both ends.
[0066] e. Arrange freezing station, install equipment, connect pipes, insulate and test instruments, dissolve calcium chloride and fill fluorine and oil into the unit.
[0067] f. After the grouting is completed, the holes are sealed with hydrophilic epoxy resin concrete and freezing construction is started, maintaining the minimum brine temperature at -30 to -28°C until the reinforcement of the designed freezing area is completed.
[0068] Example 5
[0069] The soil layers of a subway communication channel in Changzhou are fill layer, clay layer, silty clay layer, silty sand and silty soil layer, silty sand layer, sandy silty soil and silty clay layer from top to bottom. The stratum where the communication channel is located is sandy silty soil and silty clay layer. The buried depth of the communication channel is 14m. The reinforcement project adopts the combined reinforcement of pre-grouting and horizontal freezing method at the bottom of the communication channel. According to the designer's requirements, the reinforcement depth of the communication channel is 7m.
[0070] This project adopts the technology of pre-grouting at the bottom to control post-construction melting and settlement. The specific technical scheme is as follows:
[0071] a. Arrangement of grouting holes. When the shield advances and splices the pipe segments, pipe segments with reserved grouting holes are used on both sides of the communication channel, 3 pieces on each side, for a total of 6 pieces. Three rows of grouting holes are set on both sides of the communication channel in the part close to the designed freezing range at the bottom of the communication channel. The first row has an angle of 20° with the center line of the tunnel, and 6 grouting holes are arranged with a spacing of 50cm; the second row has an angle of 55° with the center line of the tunnel, and 6 grouting holes are arranged with a spacing of 50cm; the third row has an angle of 75° with the center line of the tunnel, and 6 grouting holes are arranged with a spacing of 50cm; the spacing between the first row and the second row is 50cm, and the spacing between the second row and the third row is 50cm.
[0072] b. Grouting pipe arrangement: drill grouting pipes into the reserved grouting holes for grouting. Φ25mm seamless steel pipe grouting pipes are used, with a length of 1m per section. The first row of grouting pipes is inserted into the soil from the grouting holes at a direction of 45° to the bottom of the designed freezing range. The second and third rows of grouting pipes are inserted into the soil from the grouting holes at a direction of 60°. The design reinforcement depth of the grouting pipes arranged in the third row of grouting holes is 7m, divided into 7 sections of grouting pipes, and the grouting depth of each time is 1m, that is, segmented grouting, each time 1m of grouting pipe is inserted, and the next section of grouting pipe is inserted after the grouting is completed; the design reinforcement depth of the grouting pipes arranged in the second row of grouting holes is 7m, divided into 7 sections of grouting pipes, and segmented grouting; the design reinforcement depth of the grouting pipes arranged in the first row of grouting holes is 5m, divided into 5 sections of grouting pipes, and segmented grouting.
[0073] c. Grouting materials and parameters. The grouting equipment is a BW250 variable speed grouting pump. The grouting slurry is mainly cement-water glass double liquid slurry, supplemented by single liquid cement slurry. The volume ratio of cement slurry and water glass solution is 3:1, of which the water-cement ratio of cement slurry is 1:1.25, the concentration of water glass is 35Be′, the grouting pressure is 0.6MPa, and the grouting flow rate is controlled at 1.6m 3 / h.
[0074] d. Grouting principles and methods: First, grout the grouting holes of the pipe segments on both sides of the bottom of the left line connection channel. After the left line is fully grouted, grout the right line. Pre-grouting follows the principle of small amount, multiple times, multiple points, and uniformity. Grout each section according to the designed depth. When grouting, start grouting from the grouting hole in the middle of the first row, and then pour into the grouting holes at both ends in turn; then start grouting from the grouting holes at both ends of the second row, and then pour into the grouting holes in the middle in turn. Then grout from the grouting hole in the middle of the third row to the grouting holes at both ends.
[0075] e. Arrange freezing station, install equipment, connect pipes, insulate and test instruments, dissolve calcium chloride and fill fluorine and oil into the unit.
[0076] f. After the grouting is completed, the holes are sealed with hydrophilic epoxy resin concrete and freezing construction is started, maintaining the minimum brine temperature at -30 to -28°C until the reinforcement of the designed freezing area is completed.
Claims
1. A method for controlling thawing and settling after freezing construction using a pre-grouting system at the bottom of a communication channel, characterized in that: The system is provided with three rows of grouting holes within the designed freezing range (9) at the bottom of the connecting channel, and each row of grouting holes has seven holes. Grouting pipes are inserted from the grouting holes into the designed freezing range (9). The angle between each row of grouting holes and the center line of the tunnel is 10°-80°, and the angle between the grouting pipe and the center line of the tunnel is 15°-75°. The three rows of grouting holes are respectively the first grouting holes (1), the second grouting holes (2), and the third grouting holes (3). Each row of grouting holes is symmetrically arranged along the center line (7) of the connecting channel. The method comprises the following steps: a. Arrangement of grouting holes: When the shield advances and splices the pipe segments, pipe segments with reserved grouting holes are used on both sides of the communication channel, and the left and right lines are symmetrically arranged; b. Grouting pipe arrangement: drill into the grouting pipe from the reserved grouting hole to carry out grouting. The grouting pipe is arranged in sections; c. Grouting materials and parameters: The grouting slurry is mainly cement-water glass double liquid slurry, supplemented by single liquid cement slurry. The grouting pressure is 0.2-0.8MPa, and the grouting flow rate is controlled at 1.0-2.0m 3 / h; d. Grouting principles and methods: First, grout the grouting holes of the pipe segments on both sides of the bottom of the left line communication channel. After the left line is fully grouted, grout the right line. The pre-grouting follows the principle of small amount, multiple times, multiple points and uniformity. Grouting is carried out section by section according to the designed depth. When grouting, start grouting from the middle grouting hole of the first row, and then pour into the grouting holes at both ends in turn; then start grouting from the grouting holes at both ends of the second row, and then pour into the middle grouting hole in turn, and then grout from the middle grouting hole of the third row to the grouting holes at both ends; e. Arrange freezing station, install equipment, connect pipes, insulate and test instruments, dissolve calcium chloride and fill fluorine and oil for the unit; f. After the grouting is completed, the holes are sealed with hydrophilic epoxy resin concrete. After curing, the freezing construction begins, maintaining the minimum brine temperature at -30°C until the reinforcement of the designed freezing area is completed.
2. The method for controlling thawing settlement after freezing construction by a pre-grouting system at the bottom of a communication channel according to claim 1 is characterized in that: The included angle between the first grouting hole (1) and the tunnel centerline is 15°, the included angle between the second grouting hole (2) and the tunnel centerline is 30°, and the included angle between the third grouting hole (3) and the tunnel centerline is 60°.
3. The method for controlling thawing settlement after freezing construction by a pre-grouting system at the bottom of a communication channel according to claim 1 is characterized in that: The ratio of the spacing between the first grouting hole (1) and the second grouting hole (2) to the spacing between the second grouting hole (2) and the third grouting hole (3) is 1:2-1:0.
8.
4. The method for controlling thawing settlement after freezing construction by a pre-grouting system at the bottom of a communication channel according to claim 1 is characterized in that: The grouting pipes corresponding to the first grouting hole (1), the second grouting hole (2) and the third grouting hole (3) are respectively the first grouting pipe (4), the second grouting pipe (5) and the third grouting pipe (6), wherein the angle between the first grouting pipe (4) and the tunnel centerline is 45°, and the angle between the second grouting pipe (5) and the third grouting pipe (6) and the tunnel centerline is 60°.
5. The method for controlling thawing settlement after freezing construction by a pre-grouting system at the bottom of a communication channel according to claim 4 is characterized in that: The first grouting pipe (4), the second grouting pipe (5) and the third grouting pipe (6) are all segmented grouting pipes, and the ratio of grouting depths is 1:2:2.