Method for reducing coastal shield launching risk

Abstract

The invention discloses a method for reducing coastal shield launching risk, and relates to the technical field of tunnel construction, and the method comprises the following steps: S1, in-hole horizontal grouting reinforcement: in-hole horizontal grouting performs full-section grouting along a tunnel portal range, and adopts a drilling and grouting all-in-one machine to perform retreating grouting; s2, ground vertical grouting reinforcement is conducted, and ground vertical reinforcement is conducted on a tunnel body and the left side and the right side of the tunnel body in the axis direction of the tunnel; s3, grouting effect detection, wherein one or more of the three methods of in-hole horizontal drilling water seepage amount measurement, in-hole image observation inspection and earth surface drilling coring is / are adopted for grouting effect detection; s4, a steel sleeve is installed, specifically, the steel sleeve is installed at the starting end of the tunnel; and S5, a starting sealing device is installed, a shield tail brush is arranged in the steel sleeve, and a sealing cavity is formed. Through the arrangement, the method for reducing the coastal shield launching risk is provided, and the problems of water leakage, water gushing and sand gushing of a launching tunnel portal in the near sea area shield launching process are solved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a method for reducing the starting risk of a shield machine near the sea. Background Art

[0002] With the continuous development of underground engineering, more and more cross-sea shield tunnel projects have begun to be built. Shield construction is an underground project, facing many uncertain factors such as abundant groundwater and unclear geological conditions. During the initial operation of the shield, risks such as water and sand gushing from the tunnel portal are prone to occur. Grouting and other methods are required to reinforce the starting end of the shield before starting.

[0003] At present, conventional shield tunneling reinforcement measures include: using high-pressure jet grouting piles to reinforce the tunnel body and surrounding areas along the tunnel axis, and installing water-stop curtains at the tunnel portal.

[0004] The shortcomings are as follows: the reinforcement of the starting end of the coastal shield machine faces the characteristics of limited surface construction space, abundant groundwater within the reinforcement range and connected with seawater, large influence of tidal effects, and difficulty in protecting seawalls. It is difficult to ensure the safety of the starting end of the coastal shield machine by using conventional starting methods. Summary of the invention

[0005] The purpose of the present invention is to solve the defects in the prior art and to propose a method for reducing the risk of starting a shield machine near the sea, so as to solve the problem of water leakage and water and sand gushing in the starting tunnel during the starting of a shield machine near the sea.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for reducing the risk of starting a shield machine near the sea, comprising the following steps:

[0008] S1: Horizontal grouting reinforcement in the tunnel. Horizontal grouting in the tunnel is carried out along the entire section of the tunnel portal, and the drilling and grouting machine is used for backward grouting;

[0009] S2: Ground vertical grouting reinforcement, vertical reinforcement of the tunnel body and its left and right sides within 2-5m along the tunnel axis, the reinforcement depth is within the tunnel body and 2-5m above and below the tunnel;

[0010] S3: Grouting effect detection, which adopts one or more of the following three methods: measuring water seepage by horizontal drilling in the hole, observing the image in the inspection hole, and coring by surface drilling;

[0011] S4: Steel sleeve installation: install the steel sleeve at the tunnel starting end;

[0012] S5: Initial sealing device installation, shield tail brush is set in the steel sleeve to form a sealing cavity.

[0013] Furthermore, step S1 specifically includes:

[0014] S1.1: Determine the spacing and layout of the double-liquid grouting holes;

[0015] S1.2: Position the drilling rig, drill holes, and set the double-liquid grouting pipe at the predetermined depth;

[0016] S1.3: Inject clean water and let it flow out from the end of the slurry mixer to check whether the pipeline is unobstructed;

[0017] S1.4: Cement slurry and water glass are respectively introduced into the slurry mixing section through two grouting pressure units and two grouting pipes, and injected into the target formation after being mixed evenly;

[0018] S1.5: Withdrawal of double-liquid grouting: During the double-liquid grouting process, when the pressure reaches the design value, stop pressurizing and withdraw part of the grout;

[0019] S1.6: Seal and clean, lift the grouting pipe out of the hole, and seal the hole with sealing material.

[0020] Furthermore, in step S1, conventional grouting materials are cement slurry and water glass slurry, and when there are large cracks underground, the grouting material is a combination of cement slurry, water glass slurry and phosphoric acid.

[0021] Furthermore, in step S1, the grouting pressure is controlled between 0.5 and 0.9 MPa, wherein the final grouting pressure of the grouting holes at the upper part of the tunnel portal is 0.5 to 0.6 MPa, and the final grouting pressure of the remaining grouting holes is 0.8 to 0.9 MPa.

[0022] Furthermore, in step S2, a double-liquid grouting construction method of cement slurry and water glass slurry is adopted, and the grouting pressure is controlled between 0.8 and 1.2 MPa, wherein the final hole pressure of the outer grouting hole is between 0.8 and 1.0 MPa, and the final hole pressure of the inner grouting hole is between 1 and 1.2 MPa.

[0023] Furthermore, the water seepage measurement by horizontal drilling in the cave includes: opening a horizontal exploration hole in the cave, draining the water after storing water in the exploration hole for more than 10 hours, observing whether the accumulated water in the hole is under pressure, and recording the water flow within a given time and the time consumed for the water to be drained;

[0024] Inspection hole image observation includes: selecting 2 to 5 inspection holes within the tunnel portal, using a borehole imager for inspection, and judging the water seepage in the hole and the reinforcement effect of the reinforcement body through image observation;

[0025] After the grouting is completed, select 2 to 5 verification holes within the surface end reinforcement range for drilling and coring to observe whether the core samples are complete, whether they are consistent with the geological survey report, and whether the reinforcement effect is satisfactory.

[0026] Furthermore, in step S4, the assembly sequence of the steel sleeve is as follows: lowering and installing the lower semicircle of the steel sleeve, lowering the shield body, lowering and installing the upper semicircle of the steel sleeve, and installing the reaction frame; and filling mortar between the steel rails at the bottom of the steel sleeve and between the shield machine and the steel sleeve.

[0027] Furthermore, it also includes step S7: during the initial start of the shield tunneling, high-grade cement mortar is used for synchronous grouting when the second or third ring is excavated, and the next ring is advanced after the synchronous grouting has initially set; the tunnel portal is sealed after the shield tail has completely entered the tunnel portal, that is, when excavating to the seventh ring, the wall grouting is started at the 0th ring and the 1st ring through the segment lifting holes.

[0028] Beneficial Effects

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention adopts a method to reduce the starting risk of coastal shield tunneling, and solves the problem of water leakage and water and sand gushing in the starting tunnel gate during the starting process of shield tunneling in the sea area. The method is to first perform horizontal grouting reinforcement at the starting tunnel gate, and then perform vertical grouting reinforcement on the ground. After the grouting is completed, the reinforcement effect is tested by using methods such as horizontal drilling in the tunnel to measure the amount of water seepage, inspection hole image observation, and surface drilling coring. After the end reinforcement is completed, the steel sleeve and the starting sealing device in the steel sleeve are installed, and the tunnel gate is grouting and sealed in time after the shield tunneling starts. Through the above method, zero leakage at the start of coastal shield tunneling is achieved, and the starting risk of coastal shield tunneling is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0032] Figure 1 Construction flow chart for reducing the risk of offshore shield tunneling;

[0033] Figure 2 This is a schematic diagram of the high-pressure jet spray end reinforcement;

[0034] Figure 3 This is a schematic diagram of the tunnel gate water-stop curtain;

[0035] Figure 4 This is a schematic diagram of the horizontal reinforcement grouting range in the tunnel at the starting end of the shield tunnel;

[0036] Figure 5 This is a schematic diagram of the horizontal reinforcement grouting range in the tunnel at the starting end of the shield tunnel;

[0037] Figure 6 This is a schematic diagram of strengthening the grouting holes for the weak areas of horizontal reinforcement grouting in the tunnel;

[0038] Figure 7 This is a schematic diagram of the construction principle of backward grouting reinforcement;

[0039] Figure 8 This is a schematic diagram of the effect of horizontal grouting in the cave;

[0040] Fig. 9 This is the layout diagram of the grouting holes;

[0041] Fig.10 This is a schematic diagram of the longitudinal section of the surface vertical reinforcement grouting;

[0042] Fig.11 It is the horizontal exploration hole distribution map;

[0043] Fig.12 It is a schematic diagram of a steel sleeve;

[0044] Fig.13 This is the schematic diagram of the second ring excavation;

[0045] Fig.14 This is a schematic diagram of the tunnel gate blocking; DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0047] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0048] Reference Figure 1-Figure 14 ,

[0049] 1. Horizontal grouting reinforcement in the tunnel

[0050] Horizontal grouting in the tunnel is carried out along the entire section of the tunnel portal, using a drilling and grouting machine with a backward grouting method, with a hole spacing of 1m and a longitudinal length of 12m. The specific grouting range is as follows:

[0051] ① Grouting order: from top to bottom, first the surroundings then the middle, first the outside then the inside.

[0052] ②Technology flow:

[0053] A. Arrange the spacing and positions of double-liquid grouting holes.

[0054] B. Position the drilling rig, drill holes, and place the double-liquid grouting pipe at the predetermined depth.

[0055] C. Inject clean water and let it flow out from the end of the slurry mixer to check whether the pipeline is unobstructed.

[0056] D. The slurry adopts double-liquid grouting, and cement slurry and water glass are respectively introduced into the slurry mixing section through two grouting pressure units and two grouting pipes, and injected into the target formation after being mixed evenly. The ratio and performance of the two slurries are adjusted according to the formation conditions.

[0057] E. Back-drawing double-liquid grouting, when applying pressure for double-liquid grouting, the pressure must be carefully controlled. When the pressure reaches the design value, stop pressurizing and back-draw a certain amount of slurry. The purpose of back-drawing is to prevent leakage, loss and other problems.

[0058] F. Seal and clean, lift the grouting pipe out of the hole, and seal the hole with cement mortar or other materials. Clean the site and check the equipment.

[0059] ③ Grouting materials:

[0060] The construction method of cement slurry + water glass slurry double liquid grouting is adopted. If there are large cracks in the ground during the construction process, and there is no pressure increase trend after long-term grouting or grouting on the surface, cement slurry, water glass slurry and phosphoric acid are used for grouting to speed up the grouting time, control the grouting range, avoid material waste and pollute the sea area.

[0061] Water-cement ratio 1:0.8~1:1; water-glass ratio 3:1~1:1; double liquid slurry volume ratio 1:1; phosphoric acid: water-glass 1:20~1:30

[0062] The slurry coagulation time is controlled at 20-40s. After the high-pressure slurry is sprayed and mixed from the double drill bit, it can be forced into the formation cracks under the action of high pressure, meet the diffusion range requirements and solidify quickly, achieving the purpose of water stopping, reinforcement and improvement of the formation.

[0063] ④ Grouting pressure control

[0064] During the construction process, the grouting pressure is adjusted in time according to the changes in the surface, structural walls and other environments. If there is an obvious trend of further pressure increase after the grouting time is maintained for 3 minutes, the grouting of this section should be stopped and the drill rod should be pulled out. The pulling distance should be controlled between 0.4 and 0.6m each time. If the pressure is stable for more than 30 minutes during the grouting process and there is no obvious trend of pressure increase, the slurry setting time needs to be appropriately adjusted.

[0065] During the horizontal grouting construction in the tunnel, the grouting pressure is controlled between 0.5 and 0.9 MPa, among which the final grouting pressure of the grouting holes on the upper part of the tunnel portal is 0.5 to 0.6 MPa, and the final grouting pressure of the remaining grouting holes is 0.8 to 0.9 MPa.

[0066] 2. Ground vertical grouting reinforcement

[0067] The ground is vertically reinforced along the tunnel axis to the tunnel body and the 3m range on both sides. The reinforcement depth is the tunnel body and the range of 3m above and below the tunnel.

[0068] ②Technological process: Horizontal grouting reinforcement in the same tunnel

[0069] ③ Grouting materials: adopt the construction method of double-liquid grouting of cement slurry + water glass slurry, and the mix ratio is the same as horizontal grouting.

[0070] ④ Pressure control: During the surface vertical grouting construction process, the grouting pressure is controlled between 0.8 and 1.2 MPa, among which the final hole pressure of the outer grouting hole is between 0.8 and 1.0 MPa, and the final hole pressure of the inner grouting hole is between 1 and 1.2 MPa.

[0071] 3. Grouting effect detection

[0072] The grouting effect is tested by three methods: measuring water seepage through horizontal drilling in the hole, observing the image inside the inspection hole, and coring on the surface.

[0073] 1) Measure water seepage by horizontal drilling in the hole: 9 holes were drilled in the horizontal hole, with a diameter of 50mm and a depth of 5m. During the test, the ball valve was closed and the water was stored for 12 hours, then the ball valve was opened to observe whether the water in the hole was under pressure. The water flow within 1 minute and the time consumed for the water to be drained were recorded, and the grouting reinforcement effect was comprehensively judged based on the recorded results.

[0074] 2) Image observation inside the inspection hole: select 3 inspection holes within the tunnel portal and use a borehole imaging device for inspection. The water seepage situation in the hole and the reinforcement effect of the reinforcement body are determined by image observation.

[0075] 3) Surface drilling and coring: After grouting is completed, select 2 to 3 verification holes within the surface end reinforcement range for drilling and coring to observe whether the core samples are complete, whether they are consistent with the geological survey report, and whether the reinforcement effect is satisfactory.

[0076] 4. Steel sleeve installation

[0077] In order to ensure the safety of the coastal shield machine, a steel sleeve is used to assist the launch. The size of the steel sleeve is determined according to the size of the shield machine and the launch shaft. Take the shield tunnel with a cutter head outer diameter of 7.02m and a segment outer diameter of 6.7m as an example:

[0078] The inner diameter of the steel sleeve is 7320mm and the total length is 11.6m, of which the starting ring beam is 0.6m and the cylinder is 11.0m. The cylinder is divided into four sections, each section is 2.5m; the connecting cylinder is 1.0m long.

[0079] The steel sleeve is assembled in the order of “lower semicircle of steel sleeve lowered into the well and installed → lowering of shield body → lowering of upper semicircle of steel sleeve into the well and installed → installation of reaction frame”. The steel sleeve and shield body are lowered into the well and connected with the portal steel ring. During the installation process, the positioning error is controlled to be no more than 1cm. Steel rails need to be welded inside the lower semicircle of the steel sleeve, and mortar is filled between the steel rails at the bottom of the steel sleeve and between the shield machine and the steel sleeve. It is ensured that the mortar has a certain strength to provide sufficient friction reaction force to prevent the shield machine from torsional twisting.

[0080] 5. Installation of the initial sealing device

[0081] Due to the use of steel sleeve for starting, it is impossible to install rubber curtains, folding pressure plates and other devices as in the conventional starting plan. Therefore, two shield tail brushes are set in the steel sleeve to form a sealed cavity. Grease is injected into the shield tail through the reserved pipe before the shield starts excavation and warehouse construction. Manual inspection is performed to ensure that the shield tail is full of grease. At the same time, it is continuously replenished during the excavation process to prevent soil, groundwater, circulating mud, synchronous grouting slurry, etc. from being lost from the gap between the shield shell and the tunnel portal when the shield starts excavation.

[0082] 6. Shield tunneling starts

[0083] After the shield machine, steel sleeve and reaction frame are installed, a steel sleeve pressure test is required. After the pressure test is qualified and the whole machine is debugged, and all preparatory work before departure is completed and all conditions have been accepted and qualified, mud and water warehouse construction and shield excavation can be carried out.

[0084] 7. Tunnel door sealing

[0085] ① Strengthen synchronous grouting

[0086] During the initial operation of the shield machine, high-grade cement mortar was used for synchronous grouting during the second and third rings of excavation (cement content was about 250kg / m 3 ), and then advance to the next ring after the synchronous grouting begins to set.

[0087] ②Secondary grouting to seal the tunnel door

[0088] To ensure that groundwater does not gush out at the tunnel entrance after the shield machine completely enters the reinforcement body and the start is completed smoothly, the tunnel entrance must be blocked after the shield tail completely enters the tunnel entrance. To prevent the shield tail from being wrapped when the tunnel entrance is blocked, when excavating to the 7th ring, the wall grouting and blocking are started at the 0th and 1st rings through the segment hoisting holes. The slurry materials are 42.5 grade cement, water and water glass, and the slurry ratio is: water: cement mass ratio = 1:1, cement slurry: water glass volume ratio = 1:1, and the grouting pressure is 0.8MPa.

[0089] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for reducing the risk of starting a shield machine near the sea, characterized in that: The following steps are involved: S1: Horizontal grouting reinforcement in the tunnel. Horizontal grouting in the tunnel is carried out along the entire section of the tunnel portal, and the drilling and grouting machine is used for backward grouting; S2: Ground vertical grouting reinforcement, vertical ground reinforcement is carried out on the tunnel body and the left and right sides within 2-5m along the tunnel axis. The reinforcement depth is within the tunnel body and the range of 2-5m above and below the tunnel; S3: Grouting effect detection, which adopts one or more of the following three methods: measuring water seepage by horizontal drilling in the hole, observing the image in the inspection hole, and coring by surface drilling; S4: Steel sleeve installation: install the steel sleeve at the tunnel starting end; S5: Initial sealing device installation, shield tail brush is set in the steel sleeve to form a sealing cavity.

2. A method for reducing the risk of starting a shield machine near the sea according to claim 1, characterized in that: Step S1 specifically includes: S1.1: Determine the spacing and layout of the double-liquid grouting holes; S1.2: Position the drilling rig, drill holes, and set the double-liquid grouting pipe at the predetermined depth; S1.3: Inject clean water and let it flow out from the end of the slurry mixer to check whether the pipeline is unobstructed; S1.4: Cement slurry and water glass are respectively introduced into the slurry mixing section through two grouting pressure units and two grouting pipes, and injected into the target formation after being mixed evenly; S1.5: Withdrawal of double-liquid grouting: During the double-liquid grouting process, when the pressure reaches the design value, stop pressurizing and withdraw part of the grout; S1.6: Seal and clean, lift the grouting pipe out of the hole, and seal the hole with sealing material.

3. A method for reducing the risk of starting a shield machine near the sea according to claim 1 or 2, characterized in that: In step S1, conventional grouting materials are cement slurry and water glass slurry. When there are large cracks underground, the grouting materials are cement slurry, water glass slurry and phosphoric acid.

4. A method for reducing the risk of starting a shield machine near the sea according to claim 1 or 2, characterized in that: In step S1, the grouting pressure is controlled between 0.5 and 0.9 MPa, wherein the final grouting pressure of the grouting holes at the upper part of the tunnel portal is 0.5 to 0.6 MPa, and the final grouting pressure of the remaining grouting holes is 0.8 to 0.9 MPa.

5. A method for reducing the risk of starting a shield machine near the sea according to claim 1, characterized in that: In step S2, a double-liquid grouting construction method of cement slurry and water glass slurry is adopted, and the grouting pressure is controlled between 0.8 and 1.2 MPa, wherein the final hole pressure of the outer grouting hole is between 0.8 and 1.0 MPa, and the final hole pressure of the inner grouting hole is between 1 and 1.2 MPa.

6. A method for reducing the risk of starting a shield machine near the sea according to claim 1, characterized in that: The horizontal drilling method for measuring water seepage in a cave includes: opening a horizontal exploration hole in the cave, draining the water after storing water in the exploration hole for more than 10 hours, observing whether the accumulated water in the hole is under pressure, and recording the amount of water flowing within a given time and the time it takes for the water to be drained; Inspection hole image observation includes: selecting 2 to 5 inspection holes within the tunnel portal, using a borehole imager for inspection, and judging the water seepage in the hole and the reinforcement effect of the reinforcement body through image observation; After the grouting is completed, select 2 to 5 verification holes within the surface end reinforcement range for drilling and coring to observe whether the core samples are complete, whether they are consistent with the geological survey report, and whether the reinforcement effect is satisfactory.

7. A method for reducing the risk of starting a shield machine near the sea according to claim 1, characterized in that: In step S4, the assembly sequence of the steel sleeve is: lower semicircle of the steel sleeve is lowered into the well and installed, the shield is lowered into the well, the upper semicircle of the steel sleeve is lowered into the well and installed, and the reaction frame is installed, and mortar is filled between the steel rails at the bottom of the steel sleeve and between the shield machine and the steel sleeve.

8. A method for reducing the risk of starting a shield machine near the sea according to claim 1, characterized in that: The step S7 is also included: During the initial operation of the shield machine, high-grade cement mortar is used for synchronous grouting when the second or third ring is excavated. After the synchronous grouting has initially set, the next ring is advanced. After the shield tail has completely entered the tunnel portal, the tunnel portal is sealed. That is, when excavation reaches the seventh ring, grouting behind the wall is started at the 0th and 1st rings through the segment lifting holes.

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