Construction method of shield tunneling under buildings

Abstract

The present application relates to the technical field of tunnel construction, and particularly relates to a construction method of shield tunneling under buildings. The method comprises the following steps: S1: marking the tunnel center line and elevation according to the line center line control pile and elevation control point; S2: reinforcing the stratum above the tunnel by using the method of "steel flower pipe pouring", and reinforcing the stratum from the tunnel center to the ground by using the method of "sleeve valve pipe pouring"; S3: laying the ground settlement monitoring network; S4: shield construction. The method inserts the double-row steel flower pipe group into the soil above the shield machine at an inclined angle and a depth, effectively improving the stability of the building; the reinforcing depth of the sleeve valve pipe is the tunnel center line of the shield, effectively reinforcing the working face in front of the shield machine, ensuring the stability of the stratum where the shield machine is located, and also ensuring the stability of the building above; in addition, subsequent grouting can be carried out when the ground settlement occurs during the shield tunneling process, ensuring the safety of the construction process.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for tunneling a building using a shield tunneling machine. Background Technology

[0002] For the unique sandy gravel strata of Chengdu, due to the frequent dewatering caused by numerous building and municipal projects in the surrounding area, anhydrous sandy gravel strata may appear during shield tunneling. When working in this stratum, the fine particles in the sandy gravel strata are washed away by the rainwater, making the stratum highly susceptible to collapse after vibration. Therefore, this type of anhydrous sandy gravel stratum caused by human-induced dewatering is extremely prone to collapse during shield tunneling. For example, in the shield tunneling section from the intermediate ventilation shaft to Jiujiang North Station of the TJ07 section of Chengdu Metro Line 17 Phase I, because the open-cut foundation pit was constructed before the shield tunneling, the shield tunneling passed through an anhydrous sandy gravel stratum caused by human-induced dewatering due to the foundation pit dewatering. There are several 3-4 story buildings above the section, with a shallow burial depth (only 1 times the shield tunnel diameter). This condition was the first of its kind encountered by Chengdu Metro, presenting high construction difficulty and extremely high construction risks.

[0003] Therefore, how to provide a construction method for shield tunneling under buildings in waterless sand and gravel strata has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a method for tunneling a shield through a building, in order to solve the technical problem of unstable construction when tunneling under a building caused by the absence of water in water-rich sandy gravel strata and the shallow burial depth of the building.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for constructing a tunnel boring machine (TBM) under a building includes the following steps:

[0007] S1: Mark the tunnel centerline and elevation based on the control stakes and elevation control points of the line centerline;

[0008] S2: The strata above the tunnel are reinforced using the "steel flower pipe casting" method, and the strata from the center of the tunnel to the ground are reinforced using the "sleeve valve pipe casting" method.

[0009] The "steel pipe casting" method includes:

[0010] a1: Install steel pipes; Determine the hole position and insertion angle of the steel pipes based on the data obtained in step S1, and insert two rows of steel pipe groups at an angle into the stratum above one side of the tunnel. Each row of steel pipe groups includes multiple steel pipes arranged sequentially along the tunnel axis. After the steel pipes are drilled, they are sealed with steel plates, and air vent valves and grouting valves are reserved on the sealing steel plates.

[0011] a2: Grouting is performed after all holes in the steel pipe are drilled;

[0012] a3: After grouting is completed, check the grouting effect;

[0013] The "sleeve valve tube casting" method includes:

[0014] b1: Install sleeve valve pipes; Determine the hole position and insertion angle of the sleeve valve pipes based on the data obtained in step S1, and insert two rows of sleeve valve pipe groups inclined to the strata on one side of the tunnel. Each row of sleeve valve pipe groups includes multiple sleeve valve pipes arranged sequentially along the tunnel axis. The grouting depth of each sleeve valve pipe is the centerline of the tunnel section.

[0015] b2: Construction of the grout-stopping section;

[0016] b3: Grouting construction;

[0017] b4: Pipe removal and subsequent grouting measures;

[0018] S3: Deploy a surface subsidence monitoring network;

[0019] S4: Shield tunneling; During the tunneling process, grouting is tracked through two rows of sleeve valve pipes based on the results of surface settlement monitoring.

[0020] Further, in step a1, the steel pipe is a seamless steel pipe with a diameter of 108mm and a wall thickness of 6mm. Holes are drilled in the pipe wall, with the grouting holes spaced 200mm laterally in two rows, and a 200cm section without drilling at the end for stopping the grouting. The steel pipe is 1.5m away from the building foundation, and the double-row steel pipe group is arranged in a 1.5*1.5m quincunx pattern for point excavation. The drilling depth is 7.5m, of which the upper 3m of the steel pipe is solid pipe and the lower 4.5m is perforated pipe, with the steel pipe at a 45° angle to the horizontal plane. A grouting hole with a depth of 5m is reserved 1.5m away from the building foundation at a longitudinal spacing of 3m.

[0021] In step a2, the grout is a cement grout with a water-cement ratio of 1:1. Grouting is performed after all the holes in the steel pipe are drilled, and the grouting sequence proceeds from the lower hole position to the higher hole position.

[0022] In step a3, the methods for checking the grouting effect include analytical method, borehole inspection method and non-destructive testing method. For sections that do not meet the requirements, additional grouting is performed. After the grouting effect is achieved, the guide pipe is filled with micro-expansion concrete, fully vibrated, and the opening of the guide pipe is smoothed with cement grout.

[0023] Further, step b1 includes:

[0024] (1) Determine the hole position and insertion angle of the sleeve valve tube based on the data obtained in step S1; after the hole position is determined, drill the hole using a drilling machine;

[0025] (2) Lower the drill rod to the bottom of the hole and use a mud pump to inject the mixed casing material into the hole through the drill rod until it reaches 0.2m above the grouting section height;

[0026] (3) Lower the sleeve valve pipe, lower the perforated pipe at the grouting part and the solid pipe at the non-grouting part; add a cap at the bottom of the sleeve valve pipe, lower the sleeve valve pipe to the bottom of the hole and the upper part is above the ground; then fill the sleeve valve pipe with water, and then slowly pull out the sleeve pipe and cover the upper part of the sleeve valve pipe with a cap.

[0027] Furthermore, in step b1, the distance between the two rows of sleeve valve pipe groups is 1m, and grouting is performed by drilling holes using φ48×6mm flexible plastic pipes.

[0028] Further, step b2 includes: after the casing is pulled out, filling the area below 1.5m from the ground with sand or gravel, and sealing the section above 1.5m from the ground to the ground and around the orifice with quick-setting cement mortar.

[0029] Furthermore, in step b3, the grouting material is 42.5 silicate cement with a water-cement ratio of 1:1; the grouting is first applied to the outer perimeter and then to the middle; the grouting of the sleeve valve pipe on the outside of the reinforced area uses a two-component grout, which is a mixture of cement grout and water glass in a ratio of 1:1; the grouting of the inner side of the reinforced area uses slurry cement grout with a water-cement ratio of 1:1.

[0030] In the initial stage of grouting, a thin grout or clean water is used for pressurized opening. During pressurization, a sudden drop in pressure and a surge in grout volume indicate that the opening has been completed. The opening pressure is 0.25 MPa, and the grouting pressure is controlled within 0.6 MPa, gradually increasing from bottom to top. After opening the ring, formal grouting begins according to the designed mix ratio. During grouting, grouting proceeds from the bottom of the hole upwards, skipping one hole at a time. Each row of holes constitutes a grouting section with a length of 50 cm. After the entire hole section is grouted, a second grouting is performed after a set interval, controlled between 10 and 30 minutes. Grouting is stopped if the ground shows a tendency to rise, or if grout leakage or cross-contamination occurs.

[0031] Further, step b4 includes: after grouting each sleeve valve pipe is completed, pull out the grouting pipe, insert a φ20mm water pipe into the bottom of the inner hole of the sleeve valve pipe, pump in clean water, and rinse the residual cement slurry inside the sleeve valve pipe; after cleaning, seal the pipe opening of the sleeve valve pipe with tape, cover the exposed sleeve valve pipe with a top cap, and secure it with iron wire; mark the pile number on the pipe body exposed above ground with paint, and make construction records.

[0032] Furthermore, in step S3, the surface subsidence monitoring network is deployed as follows:

[0033] The centerline points of the tunnel section are set at 5m intervals to avoid conflict with the main monitoring section.

[0034] Within a 50m radius of the launching or receiving tunnel shaft, a monitoring main section is set up every 10m; within a 50-100m radius of the launching or receiving tunnel shaft, a monitoring main section is set up every 20m; and within a radius exceeding 100m of the launching or receiving tunnel shaft, a monitoring main section is set up every 30m.

[0035] A settlement monitoring point is set on the ground directly above the arch of the single-line tunnel and the two arch waists. A measuring point is set in the middle part between the left and right tunnels. A measuring point is set 2 to 4 meters away from the outer edge of the left and right tunnels.

[0036] The measuring points are installed 200m in front of the cutterhead, the monitoring section closely follows the tunneling face, and the section that exits the shield tail is monitored.

[0037] Furthermore, step S4 includes: setting two high-pressure water injection ports at the earth chamber partition of the tunnel boring machine, and alternating the use of the two high-pressure water injection ports after each ring of the tunnel boring machine is advanced during the tunneling process.

[0038] Furthermore, step S4 includes: adding grouting holes on the shield tunnel segments, and grouting and reinforcing the strata within a 3.0m radius outside the tunnel from inside the tunnel, based on the geological conditions and excavation progress.

[0039] The beneficial effects of this invention are:

[0040] This invention provides a construction method for tunneling under a building using a shield tunnel, comprising the following steps: S1: Marking the tunnel centerline and elevation based on the centerline control piles and elevation control points; S2: Reinforcing the strata above the tunnel using the "steel flower pipe casting" method, and reinforcing the strata from the tunnel center to the ground using the "sleeve valve pipe casting" method; S3: Deploying a surface settlement monitoring network; S4: Shield tunneling; During the shield tunneling process, grouting is tracked through two rows of sleeve valve pipes based on the surface settlement monitoring results. This method employs a composite reinforcement scheme of single-sided double-row steel perforated pipes and sleeve valve pipes. The double-row steel perforated pipes are inserted at an angle and depth into the soil above the tunnel boring machine (the shallow foundation of the building), providing support and stabilizing the foundation, effectively improving the building's stability. The sleeve valve pipes reinforce to the tunnel centerline, effectively reinforcing the tunnel face in front of the machine, ensuring the stability of the ground beneath the machine and the building above. Furthermore, during tunneling, subsequent grouting can be performed if ground settlement occurs, ensuring the safety of the construction process. Attached Figure Description

[0041] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0042] Figure 1 A process flow diagram of the shield tunneling construction method for passing under a building, provided in an embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the installation structure of the steel perforated pipe and sleeve valve pipe in the shield tunneling construction method for passing under a building provided in an embodiment of the present invention;

[0044] Figure 3 This is a plan view of the pre-grouting holes of a building in the shield tunneling construction method provided in this embodiment of the invention.

[0045] Figure 4 This is a schematic diagram of the soil chamber partition in the shield tunneling method for passing under a building, provided in an embodiment of the present invention.

[0046] Figure 5 This is a schematic diagram of the installation of surface settlement monitoring points in the shield tunneling method for passing under buildings provided in this embodiment of the invention.

[0047] icon:

[0048] 1-Steel pipe assembly; 11-Steel pipe arrangement position; 2-Sleeve valve assembly; 3-Soil chamber partition; 31-High-pressure water injection port; 4-Mud filling box; 5-Steel protective cover; 6-Threaded steel bar; 7-Coarse sand. Detailed Implementation

[0049] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] It should be noted that in the description of this invention, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0051] It should be noted that in the description of this invention, the terms "connection" and "installation" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or a connection through an intermediate medium; they can refer to a mechanical connection or an electrical connection. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] Reference Figure 1 and Figure 2 This invention provides a method for tunneling a building using a shield tunneling machine, comprising the following steps:

[0053] S1: Mark the tunnel centerline and elevation based on the control stakes and elevation control points of the line centerline;

[0054] S2: The strata above the tunnel are reinforced using the "steel flower pipe casting" method, and the strata from the center of the tunnel to the ground are reinforced using the "sleeve valve pipe casting" method.

[0055] The "steel pipe casting" method includes:

[0056] a1: Install steel pipes; Determine the hole position and insertion angle of the steel pipes based on the data obtained in step S1, and insert two rows of steel pipe groups 1 at an angle into the stratum above one side of the tunnel. Each row of steel pipe groups 1 includes multiple steel pipes arranged sequentially along the tunnel axis. After the steel pipes are drilled, they are sealed with steel plates, and air vent valves and grouting valves are reserved on the sealing steel plates.

[0057] a2: Grouting is performed after all holes in the steel pipe are drilled;

[0058] a3: After grouting is completed, check the grouting effect;

[0059] The "sleeve valve tube casting" method includes:

[0060] b1: Install sleeve valve pipes; Determine the hole position and insertion angle of the sleeve valve pipes based on the data obtained in step S1, and insert two rows of sleeve valve pipe groups 2 inclined towards the strata on one side of the tunnel. Each row of sleeve valve pipe groups 2 includes multiple sleeve valve pipes arranged sequentially along the tunnel axis. The grouting depth of each sleeve valve pipe is the centerline of the tunnel section.

[0061] b2: Construction of the grout-stopping section;

[0062] b3: Grouting construction;

[0063] b4: Pipe removal and subsequent grouting measures;

[0064] S3: Deploy a surface subsidence monitoring network;

[0065] S4: Shield tunneling; During the tunneling process, grouting is tracked through two rows of sleeve valve pipes based on the results of surface settlement monitoring.

[0066] Reference Figure 3 In step a1, two rows of steel pipes are inserted radially into the strata above the tunnel along the edge of the building. The pouring process for the steel pipes arranged radially along the tunnel is the same as that for the steel pipes arranged axially along the tunnel. Figure 3 As shown, multiple steel pipe arrangement positions 11 are set at the edges of the building parallel to the tunnel axis and at the edges of the building parallel to the tunnel radial direction, so that steel pipes are set along the radial direction and one-sided axis of the tunnel, further improving the stability of the building above.

[0067] In step a1, after the location of the steel pipe borehole is determined, manual exploration is required. A YGL-100 crawler drilling rig is used. After assembly, it is hoisted to the working platform using a 25t truck crane. Drilling is carried out using a horizontal geological drilling rig. During the drilling process, a horizontal inclinometer should be used to frequently measure the deviation of the pipe roof. If the deviation exceeds the design requirements, it should be corrected promptly. The steel pipe is a seamless steel pipe with a diameter of φ108mm and a wall thickness of 6mm. Holes are drilled in the pipe wall of the pipe roof, with a lateral spacing of 200mm between the grouting holes, arranged in two rows. The tail end is a 200cm section without drilling for grout stopping. The number of joints on the same cross-section of the steel pipe must not exceed [a certain number]. 50% of the pipes; the steel perforated pipes are installed using pipe-following drilling, with each section of the pipe roof being extended in 1.5m increments, and the two sections are connected by threaded connections, with the threaded section length greater than 150mm; the steel perforated pipes are 1.5m away from the building foundation, and the double-row steel perforated pipe group 1 is arranged in a 1.5*1.5m quincunx pattern for point excavation; the drilling depth is 7.5m, of which the upper 3m of the steel perforated pipes are solid pipes, and the lower 4.5m are perforated pipes, with the steel perforated pipes forming an angle of 45° with the horizontal plane; to promptly replenish grout for possible surface settlement during the excavation process, a grouting hole with a depth of 5m is reserved 1.5m away from the building foundation, with a longitudinal spacing of 3m.

[0068] In step a2, grouting is achieved by connecting the pre-reserved grouting valve on the sealing steel plate to the grouting pump's delivery pipe. The grout used is a cement grout with a water-cement ratio of 1:1. Grouting is performed after all the steel perforated pipes are drilled, proceeding from lower to higher hole positions. Single-liquid grouting is performed on the steel perforated pipes. The designed grouting pressure is 0.2–0.4 MPa. If the grouting pressure is 1.5 times higher than the design pressure and the pressure continues to rise, the grout gelation time is adjusted or intermittent grouting is used. Grouting is stopped once the test grouting pressure reaches the designed medium pressure. Because the spacing between the steel perforated pipes is small, grouting after all holes are drilled and proceeding from lower to higher hole positions avoids cross-hole blockage caused by grouting. This allows the grout to diffuse and fill the loose rock layer, consolidating the broken rock. This reduces rock fragmentation during drilling of adjacent holes, prevents drill bit jamming, and accelerates the construction progress.

[0069] In step a3, the methods for checking the grouting effect include:

[0070] 1) Analytical method

[0071] After grouting is completed, statistical analysis of the drilling grouting records is performed to check whether each hole has met the grouting completion standard, whether all grouting holes have been reinforced with grout, and whether there are any omissions in the grouting.

[0072] 2) Non-destructive testing method

[0073] After grouting is completed, a ground-penetrating radar system is used to detect the geological conditions of the grouting area and check for cavities or loose areas. If any are found, grouting should be carried out in time to fill the holes.

[0074] 3) Drilling inspection method

[0075] If necessary, borehole inspections should be conducted to check the grout filling in the grouting reinforcement area. A geological borehole machine should be used for drilling, selecting three different areas, with one borehole selected from each area to check the grouting effect.

[0076] For sections that do not meet the requirements for grouting effect, fill the holes with grout; after the grouting effect is achieved, fill the guide pipe with micro-expansion concrete, vibrate it thoroughly, and smooth the guide pipe opening with cement grout.

[0077] Step b1 includes:

[0078] (1) Based on the data obtained in step S1 (according to the tunnel centerline and building edge line), determine the hole position and insertion angle of the sleeve valve pipe. The angle between the sleeve valve pipe and the horizontal plane can be between 20° and 45°. For example, the angle between the upper row of sleeve valve pipes and the horizontal plane is 30°, and the angle between the lower row of sleeve valve pipes and the horizontal plane is 23°. Specifically, first use a total station to measure and mark the coordinates of the two outermost points on both sides of each row. Then, using these coordinates, determine the positions of other drill holes between the two points by using a string line and a measuring tape. After determining the hole positions, mark them with paint. After the hole positions are determined, use... YGL-100 engineering geological drilling rig construction; to ensure the bottom of the drilling rig is flat and stable, the verticality of the drill bit and the borehole is checked using a hammer drill bit before drilling begins, and the drilling rig needs to be leveled and corrected after drilling 2m and after each additional section of drill rod; the drilling rig creates holes with mud wall protection, and grouting is applied from bottom to top. If a turning hole is encountered, the hole spacing should be adjusted appropriately to ensure a tight connection between the turning hole and the adjacent hole; the drilling rig uses mud wall protection for hole creation, and the hole depth is in accordance with the design requirements. The spacing between the two rows of sleeve valve pipe groups 2 is 1m, and φ48×6mm flexible plastic pipes are used for drilling and grouting;

[0079] (2) Lower the drill rod to the bottom of the hole and use a mud pump to inject the mixed casing material into the hole through the drill rod until it reaches 0.2m above the grouting section height; within the grouting section, casing material (casing material is clay-cement grout, with a mix ratio of cement:clay:water = 1:1.50:1.88) should be poured to prevent the sleeve valve grouting pipe from deforming, shifting or being damaged during the grouting process, and to allow the cement grout to pass through; the casing material should have low shrinkage, high brittleness and high early strength;

[0080] (3) Lower the sleeve valve pipe. The sleeve valve pipe is a φ48×6mm flexible plastic pipe with a segment length of 0.5m. The perforated pipe is lowered at the grouting part and the solid pipe is lowered at the non-grouting part. A cap is added to the bottom of the sleeve valve pipe. The sleeve valve pipe is lowered to the bottom of the hole and the top is above the ground. Then fill the sleeve valve pipe with water. After that, slowly pull out the sleeve pipe and cover the top of the sleeve valve pipe with a cap to prevent debris from entering the sleeve valve pipe and affecting the quality of the grouting operation.

[0081] Step b2 includes: after the casing is pulled out, sand or gravel is used to fill the area below 1.5m from the ground, and quick-setting cement mortar is used to seal the section from 1.5m above the ground to the ground and around the borehole to prevent grout leakage during the grouting process.

[0082] In step b3, 42.5 silicate cement is used as the grouting material, with a water-cement ratio of 1:1. Grouting is performed first on the outer perimeter and then on the middle. For grouting the sleeve valve pipes on the outer side of the reinforced area, a two-component grout is used, consisting of cement grout and water glass mixed in a 1:1 ratio. For the inner side of the reinforced area, a slurry-cement grout with a water-cement ratio of 1:1 is used. This setup achieves the goal of forming a wall on the outer perimeter and compacting the interior, while also ensuring that the grout is not affected by the pit dewatering during grouting, thus guaranteeing the grout diffusion effect.

[0083] In step b3, during the initial stage of grouting, a thin grout or clean water is used for pressurized opening of the ring. During pressurization, a sudden drop in pressure and a sharp increase in grout volume indicate that the ring has been opened. The opening pressure is 0.25 MPa, and the grouting pressure is controlled within 0.6 MPa, gradually increasing from bottom to top. After opening the ring, formal grouting begins according to the designed mix ratio. During grouting, grouting is carried out from the bottom of the hole upwards, skipping one hole at a time. Each row of holes constitutes a grouting section with a length of 50 cm. After the entire hole section is grouted, a second grouting is performed after a set interval, with the set interval controlled between 10 and 30 minutes. Grouting is stopped if the ground shows a tendency to rise, or if grout leakage or cross-contamination occurs.

[0084] Step b4 includes: After grouting of each sleeve valve pipe is completed, pull out the grouting pipe, insert a φ20mm water pipe into the bottom of the inner hole of the sleeve valve pipe, pump in clean water, and rinse the residual cement slurry in the sleeve valve pipe to prepare for secondary grouting; after cleaning, seal the pipe opening of the sleeve valve pipe with tape, cover the exposed sleeve valve pipe with a top cap, and tie it firmly with iron wire; mark the pile number on the pipe body exposed above the ground with paint, and make construction records to prepare for subsequent grouting when the ground settles during the subsequent shield tunneling process.

[0085] As the most important control indicator for shield tunneling sections, the layout of monitoring sections should fully consider the characteristics of shield tunneling construction. During the shield launching and arrival stages, due to the disturbance of the strata caused by the excavation and reinforcement of the shield shaft (launching or receiving), the soil in this section is prone to collapse and significant surface settlement during the tunneling machine's excavation, endangering the safety of surrounding ground structures and underground pipelines. Especially at the time of shield launching, when earth pressure balance has not yet been established or the balance is not stable, the excavation will cause significant stratum loss and reduce the bearing capacity of the strata. Since this section mainly passes through important urban roads, especially in areas with high traffic volume, shield tunneling construction is prone to various accidents.

[0086] Taking into account various factors, the deployment method of the surface subsidence monitoring network in step S3 is as follows:

[0087] The centerline points of the tunnel section are set at 5m intervals to avoid conflict with the main monitoring section.

[0088] Within a 50m radius of the launching or receiving tunnel shaft, a monitoring main section is set up every 10m; within a 50-100m radius of the launching or receiving tunnel shaft, a monitoring main section is set up every 20m; and within a radius exceeding 100m of the launching or receiving tunnel shaft, a monitoring main section is set up every 30m.

[0089] One settlement monitoring point is set on the ground directly above the arch of the single-line tunnel and the two arch waists. One monitoring point is set in the middle of the left and right tunnels. One monitoring point is set 2 to 4 meters from the outer edge of the left and right tunnels. In this way, no less than 11 settlement monitoring points are set up in each monitoring section.

[0090] The measuring points are installed 200m in front of the cutterhead, the monitoring section closely follows the tunnel face, and the section that has exited the shield tail is monitored; during the monitoring process, initial values ​​need to be taken in advance for subsequent comparison.

[0091] Throughout the entire shield tunneling process, the building is systematically and comprehensively monitored and measured through a surface settlement monitoring network (including building deformation monitoring). Information-based construction is implemented, and depending on the monitoring results, follow-up grouting is used as an effective supplementary measure to protect the building (structure).

[0092] In step S3, for key areas, such as those crossing buildings, rivers, or important pipelines, the number of monitoring points and items should be appropriately increased to ensure the continuity of monitoring data and to accurately reflect the actual settlement and deformation of the section, so as to ensure construction safety and quality. Considering that surface monitoring has certain limitations in judging the actual state of the strata, on-site monitoring should also be combined with on-site intuitive feelings and observations, and the results should be reported in a timely manner.

[0093] Reference Figure 5 Ground settlement monitoring points are arranged on the surface within the construction impact area according to the monitoring and measurement design requirements in the design drawings. Before setting up the monitoring points, pipelines must be checked based on the pipeline detection results of the construction unit. The principles for setting up settlement points are as follows: Ground settlement monitoring point markers are in the form of pit monitoring points, which are buried by manual excavation or drilling. They are required to penetrate the road structure layer and be buried 20cm into the original soil layer. 6 threaded steel bars and 7 coarse sand are placed in the hole, and the hole opening is covered with a steel protective cover 5. The hole diameter shall not be less than 110mm. The monitoring points for road and ground settlement monitoring should be buried on a flat surface to prevent unevenness from affecting the passage of people and vehicles. At the same time, the monitoring points should be buried firmly, clearly marked, and easy to preserve.

[0094] Building settlement monitoring can be shared with the surface settlement leveling monitoring network, incorporating building settlement monitoring points into closed loops, attached loops, etc. Different methods of burying building settlement monitoring point markers are used depending on the monitoring object: drilled holes are used for frame and brick-concrete structures, welded points are used for steel structures, and concealed points are used for structures with special finishes. When burying various settlement monitoring points, care should be taken to avoid obstacles that may hinder marker placement and observation, such as rainwater pipes, window sills, and electrical switches. The measuring rod should be placed a certain distance away from the wall (column) surface and the ground, generally 0.2–0.5 m above the indoor floor level. After the monitoring point is buried, an anti-corrosion agent should be applied to the measuring rod end.

[0095] Step S4 includes: installing two high-pressure water injection ports 31 at the earth chamber partition 3 of the tunnel boring machine (TBM). During the TBM's tunneling process, the two high-pressure water injection ports 31 are used alternately after each ring of the TBM is advanced. (Refer to...) Figure 4 Two pipelines are installed at the mud filling box 4 and the soil chamber partition 3 of the rotating soil chamber. Two high-pressure water injection ports 31 are installed at the soil chamber partition 3 to continuously inject water into the center of the soil chamber. The injection ports are selected to be the left center and the right center. During the advancement process, only the ball valve of one injection port is opened. After each ring of advancement, the other ball valve is opened, and the two are used alternately. The above settings can ensure smooth shield construction and prevent mud cake formation inside the soil chamber.

[0096] Step S4 further includes: adding grouting holes on the shield tunnel segments, and grouting and reinforcing the strata within a 3.0m radius outside the tunnel from inside the tunnel, based on the geological conditions and excavation progress. Optionally, each shield tunnel segment is provided with at least one grouting hole, thereby forming multiple groups of grouting holes distributed along the tunnel axis inside the tunnel, and each group of grouting holes includes multiple grouting holes distributed along the tunnel circumference; through the above arrangement, grouting and reinforcement of the strata outside the tunnel can be carried out from inside the tunnel, and subsequent grouting can be carried out from inside the tunnel to the outside when ground settlement occurs, ensuring the safety of the construction process.

[0097] According to construction efficiency statistics, the foundation reinforcement period for a single building using this method is within 20 days. For the same type of building, the traditional method (i.e., indoor ground grouting) requires at least 37 days of occupancy for both the residential area and foundation reinforcement. Furthermore, based on the analysis of settlement monitoring results between the machine and the final shield tunnel section, this method can effectively improve ground stability and reduce the risk of the shield tunnel passing underneath. Compared with the original indoor grouting reinforcement scheme, this method demonstrates significant benefits and has value for widespread application.

[0098] The construction method provided in this application adopts a composite reinforcement scheme of single-sided double-row steel perforated pipes and sleeve valve pipes. The double-row steel perforated pipes are inserted into the soil above the tunnel boring machine (the shallow foundation of the building) at a large oblique angle and depth, providing support and stabilizing the shallow foundation, effectively improving the stability of the building. The reinforcement depth of the sleeve valve pipes is along the tunnel centerline, effectively reinforcing the working face in front of the tunnel boring machine, ensuring the stability of the strata where the tunnel boring machine is located, and also ensuring the stability of the building above. The single-sided double... While using inclined steel pipes and single-sided inclined sleeve valve pipes for grouting reinforcement, the soil chamber of the tunnel boring machine (TBM) is optimized by adding high-pressure nozzles at the center of the chamber's rotation position. This ultimately achieves the goal of safe, efficient, and stable TBM tunneling through structures, with controllable settlement of the structures simultaneously. After TBM excavation, grouting reinforcement of the ground outside the tunnel can be carried out from inside the tunnel through grouting holes on the tunnel segments. Furthermore, by rationally deploying a surface settlement monitoring network, subsequent grouting can be carried out when ground settlement occurs during TBM excavation, ensuring the safety of the construction process. This method effectively guarantees the stability of the sand and gravel soil layer and the stability of the structure during TBM tunneling under buildings, ensuring both the safety and progress of construction.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a tunnel boring machine (TBM) under a building, characterized in that, Includes the following steps: S1: Mark the tunnel centerline and elevation based on the control stakes and elevation control points of the line centerline; S2: The stratum above the tunnel is reinforced using the "steel flower pipe casting" method, and the stratum from the center of the tunnel to the ground is reinforced using the "sleeve valve pipe casting" method. The "steel pipe casting" method includes: a1: Install steel pipes; Determine the hole position and insertion angle of the steel pipes based on the data obtained in step S1, and insert two rows of steel pipe groups at an angle into the stratum above one side of the tunnel. Each row of steel pipe groups includes multiple steel pipes arranged sequentially along the tunnel axis. After the steel pipes are drilled, they are sealed with steel plates, and air vent valves and grouting valves are reserved on the sealing steel plates. a2: Grouting is performed after all holes in the steel pipe are drilled; a3: After grouting is completed, check the grouting effect; The "sleeve valve tube casting" method includes: b1: Install sleeve valve pipes; Determine the hole position and insertion angle of the sleeve valve pipes based on the data obtained in step S1, and insert two rows of sleeve valve pipe groups inclined to the strata on one side of the tunnel. Each row of sleeve valve pipe groups includes multiple sleeve valve pipes arranged sequentially along the tunnel axis. The grouting depth of each sleeve valve pipe is the centerline of the tunnel section. b2: Construction of the grout-stopping section of the pipe; b3: Grouting construction; b4: Pipe removal and subsequent grouting measures; S3: Deploy a surface subsidence monitoring network; S4: Shield tunneling; During the tunneling process, grouting is tracked through two rows of sleeve valve pipes based on the results of surface settlement monitoring.

2. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, In step a1, seamless steel pipes with a diameter of 108mm and a wall thickness of 6mm are used for the steel pipe shed. Holes are drilled in the pipe wall, with the grouting holes spaced 200mm laterally in two rows. The tail end is a 200cm section without drilling for grout stopping. The steel pipe shed is 1.5m away from the building foundation. The double-row steel pipe shed is arranged in a 1.5*1.5m quincunx pattern for point excavation. The drilling depth is 7.5m. The upper 3m of the steel pipe shed is solid pipe, and the lower 4.5m is perforated pipe. The angle between the steel pipe shed and the horizontal plane is 45°. A grouting hole with a depth of 5m is reserved 1.5m away from the building foundation at a longitudinal spacing of 3m. In step a2, the grout is a cement grout with a water-cement ratio of 1:

1. Grouting is performed after all the holes in the steel pipe are drilled, and the grouting sequence proceeds from the lower hole position to the higher hole position. In step a3, the methods for checking the grouting effect include analytical method, borehole inspection method and non-destructive testing method. For sections that do not meet the requirements, additional grouting is performed. After the grouting effect is achieved, the guide pipe is filled with micro-expansion concrete, fully vibrated, and the opening of the guide pipe is smoothed with cement grout.

3. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, Step b1 includes: (1) Determine the hole position and insertion angle of the sleeve valve tube based on the data obtained in step S1. After the hole position is determined, drill the hole using a drilling machine. (2) Lower the drill rod to the bottom of the hole and use a mud pump to inject the mixed casing material into the hole through the drill rod until it reaches 0.2m above the grouting section height; (3) Lower the sleeve valve pipe, lower the perforated pipe at the grouting part and the solid pipe at the non-grouting part; add a cap at the bottom of the sleeve valve pipe, lower the sleeve valve pipe to the bottom of the hole and the upper part is above the ground; then fill the sleeve valve pipe with water, and then slowly pull out the sleeve pipe and cover the upper part of the sleeve valve pipe with a cap.

4. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, In step b1, the distance between the two rows of sleeve valve pipe groups is 1m, and grouting is performed by drilling holes using φ48×6mm flexible plastic pipes.

5. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, Step b2 includes: after the casing is pulled out, sand or gravel is used to fill the area below 1.5m from the ground, and quick-setting cement mortar is used to seal the section from 1.5m from the ground to the ground and around the opening.

6. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, In step b3, 42.5 silicate cement is used as the grouting material, with a water-cement ratio of 1:1; the grouting is first applied to the outer perimeter and then to the middle; the grouting of the sleeve valve pipe on the outside of the reinforced area uses a two-component grout, which is a mixture of cement grout and water glass in a ratio of 1:1; the grouting of the inner side of the reinforced area uses a cement grout with a water-cement ratio of 1:

1. In the initial stage of grouting, a thin grout or clean water is used for pressurized opening. During pressurization, a sudden drop in pressure and a surge in grout volume indicate that the opening has been completed. The opening pressure is 0.25 MPa, and the grouting pressure is controlled within 0.6 MPa, gradually increasing from bottom to top. After opening the ring, formal grouting begins according to the designed mix ratio. During grouting, grouting proceeds from the bottom of the hole upwards, skipping one hole at a time. Each row of holes constitutes a grouting section with a length of 50 cm. After the entire hole section is grouted, a second grouting is performed after a set interval, controlled between 10 and 30 minutes. Grouting is stopped if the ground shows a tendency to rise, or if grout leakage or cross-contamination occurs.

7. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, Step b4 includes: After grouting is completed for each sleeve valve pipe, pull out the grouting pipe, insert a φ20mm water pipe into the bottom of the inner hole of the sleeve valve pipe, pump in clean water, and rinse the residual cement slurry inside the sleeve valve pipe; after cleaning, seal the pipe opening of the sleeve valve pipe with tape, cover the exposed sleeve valve pipe with a top cap, and secure it with iron wire; mark the pile number on the pipe body exposed above ground with paint, and make construction records.

8. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, In step S3, the surface subsidence monitoring network is deployed as follows: The centerline points in the tunnel section are set at 5m intervals to avoid conflict with the main monitoring section. Within a 50m radius of the launching or receiving tunnel shaft, a monitoring main section is set up every 10m; within a 50-100m radius of the launching or receiving tunnel shaft, a monitoring main section is set up every 20m; and within a radius exceeding 100m of the launching or receiving tunnel shaft, a monitoring main section is set up every 30m. A settlement monitoring point is set on the ground directly above the arch of the single-line tunnel and the two arch waists. A measuring point is set in the middle part between the left and right tunnels. A measuring point is set 2 to 4 meters away from the outer edge of the left and right tunnels. The measuring points are installed 200m in front of the cutterhead, the monitoring section closely follows the tunneling face, and the section that exits the shield tail is monitored.

9. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, Step S4 includes: setting two high-pressure water injection ports at the earth chamber partition of the tunnel boring machine. During the tunnel boring machine's excavation, the two high-pressure water injection ports are used alternately after each ring of the tunnel boring machine is advanced.

10. The construction method for tunneling a building using a shield tunneling machine according to claim 1, characterized in that, Step S4 includes: adding grouting holes on the shield tunnel segments, and grouting and reinforcing the strata within a 3.0m radius outside the tunnel from inside the tunnel, based on the geological conditions and excavation progress.

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