A pre-reinforcement device and method for tunnel passing through saturated sand

Abstract

A pre-reinforcement device and method for a tunnel passing through saturated sand belongs to the technical field of tunnel construction. The invention mainly comprises five parts: a transport control device (1), a grouting device (2), a pipeline system (3), a drainage device (4), and an intelligent monitoring and control system (5). The invention adopts a drainage induction and displacement grouting device and method to perform grouting on the tunnel surrounding rock area in the saturated sand area, thereby achieving the effect of reinforcing the tunnel surrounding rock.

Description

Technical Field

[0001] The invention relates to a tunnel surrounding rock reinforcement device and a construction method for a tunnel passing through a saturated sandy soil section, which mainly solves the technical problem of tunnel construction in the saturated sandy soil section and belongs to the technical field of tunnel construction. Background Art

[0002] Saturated sand has low strength and poor self-stabilization ability during tunnel excavation. When groundwater is abundant and construction machinery disturbs the soil, it liquefies and the face rock becomes unstable and unable to bear its own load, resulting in collapse and engineering accidents. When a tunnel passes through a saturated sandy area, it is necessary to pre-reinforce the area to be traversed to block water and reinforce it, so that the surrounding rock has a certain bearing capacity and self-stabilization ability, and ensure that the soil will not collapse after excavation.

[0003] Tunnel pre-reinforcement grouting can effectively fill the gaps between sand and soil. When the slurry reaches a certain strength, it can bond the sand particles in the saturated sand together, and form a surrounding rock reinforcement area with high strength in the saturated sand, ensuring that the tunnel has stable surrounding rock and water-stopping effects when passing through the saturated sand area. The grouting reinforcement methods usually used in tunnel pre-reinforcement are mainly based on the diffusion theory, dynamic water grouting theory, compaction grouting diffusion theory and splitting grouting diffusion theory. The transportation and installation of the grouting device are often time-consuming and labor-intensive. The direction of grouting is uncertain in the process, the slurry diffuses randomly in the soil, the shape of the reinforced area in the soil is quite different from the shape required for construction, and the grouting effect is not ideal.

[0004] The present invention provides a new engineering pre-reinforcement treatment scheme for tunnel excavation in saturated sand soil, and performs pre-reinforcement and sealing and water stopping when the tunnel passes through the saturated sand soil layer, thereby ensuring normal tunnel construction. Summary of the invention

[0005] The present invention provides a pre-reinforcement device and method for a tunnel passing through saturated sand soil. The pre-reinforcement device and method are based on the induction and displacement principles. Directional drainage induction is performed in the sand soil layer to form a displacement channel in the saturated sand soil layer. Injectable cement slurry is used to displace groundwater in the saturated sand soil layer along the negative pressure induction channel, fills and retains in the saturated sand soil layer, and forms an ideal grouting slurry solid together with the sand soil, thereby reinforcing the soft soil layer and closing the groundwater flow channel, thereby performing advanced pre-reinforcement on the tunnel.

[0006] The present invention mainly comprises five parts: a transport control device (1), a grouting device (2), a pipeline system (3), a drainage device (4), and an intelligent monitoring and control system (5).

[0007] The transport control device (1) comprises a control room (1.1) of the grouting device and a main vehicle body (1.2); the control room (1.1) includes an alarm device, a control device and a display screen in addition to basic vehicle operating equipment.

[0008] The grouting device (2) mainly comprises a slurry storage box (2.1), a grouting pump (2.2), a steel support (2.3), a grouting pressure control box (2.4), a grouting guide tube (2.5), a slurry outlet pipe (2.6), a pressure sensor (2.7), a mixer (2.8) and a grouting quantity measuring meter (2.9);

[0009] The pipeline system (3) mainly includes a grouting pipe (3.1), a drainage pipe (3.2), a first joint (3.4.1), a second joint (3.4.2), a first valve (3.5.1), and a first valve (3.5.1);

[0010] The drainage device (4) comprises a water pump (4.1), a drainage conduit (4.2), a drainage pressure control box (4.3), a transparent plastic pipe (4.4), and a drainage volume measuring meter (4.5);

[0011] The intelligent monitoring and control system (5) comprises a grouting pressure gauge (5.1), a drainage pressure gauge (5.2), and an intelligent pressure control device (5.3).

[0012] The alarm and control devices in the control room (1.1) are independent of the intelligent monitoring and control system (5).

[0013] The control room (1.1) and the grouting device (2) are carried by the main vehicle body (1.2).

[0014] The slurry storage box (2.1) is connected to the grouting pressure control box (2.4) via a grouting pump (2.2) by means of a grouting conduit (2.5), and a slurry outlet pipe (2.6) is installed at the slurry outlet of the grouting pressure control box (2.4).

[0015] The grouting pump (2.2) is connected to the main body (1.2) by means of a steel bracket (2.3).

[0016] The pressure sensor (2.7) in the grouting pressure control box (2.4) is connected to the alarm device and display screen in the control room (1.1) through a wire.

[0017] The mixer (2.8) is placed on the top of the slurry storage tank (2.1) and is connected to the control device in the control room (1.1) by means of a wire.

[0018] The pressure detection gauge (2.9) is arranged at the end of the pulp outlet pipe (2.6) and is connected to the display screen of the control room (1.1) by means of a wire.

[0019] The slurry outlet pipe (2.6) is connected to the grouting pipe (3.1) via the first conduit (3.3.1), the first joint (3.4.1) and the first valve (3.5.1).

[0020] The water inlet of the water pump (4.1) is connected to the drainage pipe (3.2) via the drainage pressure control box (4.3), the drainage meter (4.5), the second conduit (3.3.2), the second joint (3.4.2), and the second valve (3.5.2) in sequence, and the interfaces of each component are connected by threaded connection.

[0021] The water outlet of the water pump (4.1) is connected to the drainage conduit (4.2), and a section of transparent plastic pipe (4.4) is arranged in the drainage conduit (4.2).

[0022] The control room (1.1) is located on the main vehicle body (1.2). In addition to basic vehicle operations, the control room (1.1) also monitors the amount of slurry in the slurry storage tank (2.1) and the amount of slurry injected per time through the alarm device, control device and display screen therein, and controls the mixer (2.8).

[0023] A pressure sensor (2.7) is installed at the bottom of the slurry storage box (2.1). The pressure sensor (2.7) is connected to the alarm device and display screen in the control room (1.1) through a wire. The pressure value fed back by the pressure sensor (2.7) is displayed on the display screen of the control room (1.1). When the pressure value is lower than a certain value, the alarm device in the control room (1.1) sounds an alarm. The mixer (2.8) is placed inside the slurry storage box (2.1) and connected to the control device in the control room (1.1) through a wire. The stirring time and stirring time interval are set in the control device in the control room (1.1) to automatically prevent the slurry from solidifying during the grouting process. The slurry storage box (2.1) is connected to the grouting pressure control box (2.4) via the grouting pump (2.2). The grouting pressure in the grouting device (2) is reasonably adjusted through the grouting pressure control box (2.4). The grouting pressure control box (2.4) is provided with a grouting pipe (2.6), which is threaded to ensure that it can be tightly connected to the first guide tube (3.3.1). The grouting pipe (2.6) is provided with a grouting quantity meter (2.9), which is connected to the display screen of the control room (1.1) by a wire. Before grouting, the grouting quantity meter (2.9) is zeroed; during the grouting process, the grouting quantity meter (2.9) will continuously monitor the grouting quantity and feed it back to the display screen of the control room (1.1). After each grouting is completed, the single grouting quantity is recorded for the final grouting evaluation.

[0024] The grouting pipe (3.1) and the drainage pipe (3.2) are both flower pipes with holes on the side, and the ends are pointed and closed. During grouting, the slurry is evenly diffused from the small holes on the side of the grouting pipe (3.1) into the saturated sand and soil. The drainage pipe (3.2) is wrapped with a mesh to prevent the sand and soil particles around the drainage pipe (3.2) from being lost or blocking the drainage pipe (3.2). During the grouting process, a negative pressure area is formed around the drainage pipe (3.2), inducing the slurry ejected by the grouting pipe (3.1) to flow around the negative pressure pipe, thereby realizing directional grouting. Multiple grouting pipes (3.1) and drainage pipes (3.2) are arranged in a cross-spaced manner and the arrangement route is arranged according to the required process. The first conduit (3.3.1) and the second conduit (3.3.2) are both steel pipes for conveying slurry and draining water. The first valve (3.5.1) is arranged at the entrance of the grouting pipe (3.1) and is mainly used to block the entrance of the grouting pipe (3.1); the second valve (3.5.1) is arranged at the entrance of the drainage pipe (3.2) and is mainly used to block the drainage pipe (3.2) to prevent the water in the soil before grouting and the slurry in the soil after grouting from flowing in the opposite direction along the corresponding pipes; after the slurry in the grouting area solidifies, the first valve (3.5.1) and the second valve (3.5.1) can be disassembled and cleaned for recycling.

[0025] A water pump (4.1) of suitable specifications is used in the drainage device (4) to form negative pressure in the drainage device (4). The drainage conduit (4.2) uses an appropriate steel pipe to drain water. The drainage pressure control box (4.3) adjusts the pressure in the drainage device (4) and adjusts the reasonable negative pressure range to ensure the effect of grouting. A transparent plastic pipe (4.4) is installed at the drainage outlet of the system. The flow rate and consistency changes of the slurry are observed through the transparent plastic pipe (4.4) to determine whether to stop grouting. When slurry flows through the transparent plastic pipe (4.4), the valve (3.5) should be closed in time to prevent the slurry from flowing out. The drainage volume detection table (4.5) detects the drainage volume of a grouting during the grouting process for grouting effect evaluation.

[0026] Each grouting pressure gauge (5.1) is connected to the grouting pressure control box (2.4) through the intelligent pressure control device (5.3), and each drainage pressure gauge (5.2) is connected to the drainage pressure control box (4.3) through the intelligent pressure control device (5.3). During the grouting process, the grouting pressure gauge (5.1) and the drainage pressure gauge (5.2) can dynamically monitor and measure the grouting pressure and the drainage pressure, and timely feed back the pressure value to the intelligent pressure control device (5.3), and then the intelligent pressure control device (5.3) controls the grouting pressure control box (2.4) and the drainage pressure control box (4.3);

[0027] The intelligent pressure control device (5.3) is set with an automatic control program and has a plurality of interfaces. Each drainage pressure gauge (5.2), drainage pressure control box (4.3), grouting pressure control box (2.4) and drainage pressure control box (4.3) corresponds to an interface of the intelligent pressure control device (5.3).

[0028] The core content of the present invention is the displacement drainage and induced grouting construction device and technology. The interior of saturated sand can be considered as a closed area. When the water inside the soil flows in the induced direction, a certain negative pressure can be generated inside the soil. The cement slurry flows to the negative pressure area in the form of a fluid under a certain grouting pressure under the action of the pressure difference, displacing the groundwater in the soil. When the grouting pressure and the negative pressure difference in any micro-unit in the grouting soil exceed the groundwater and driving pressure in the soil, the cement slurry begins to be injected into the soil pre-reinforcement area in the expected induced direction, and the grouting area is oriented and quantitatively grouted to achieve the expected purpose of grouting reinforcement of the soil. An intelligent monitoring and control system (5) is used to intelligently monitor the grouting pressure value and negative pressure value in the entire system to ensure that the grouting speed is uniform and the grouting effect is qualified.

[0029] The method can reasonably control the grouting direction and position, improve the grouting efficiency and reduce ineffective grouting.

[0030] The specific construction sequence of the present invention is:

[0031] (I) Buried pipeline

[0032] According to the corresponding grouting specifications, the positions of the grouting holes and the drainage holes for installing the grouting pipe (3.1) and the drainage pipe (3.2) are designed. The parameters that need to be calculated in advance to determine the hole positions in the present invention include: the spacing S between the grouting holes and the drainage holes, the diameters d of the grouting pipe and the drainage pipe, the diffusion diameter D around the grouting pipe, and the number of layers w of the grouting pipe distribution; and the positions of the grouting holes and the drainage holes are reasonably arranged according to the designed parameters.

[0033] Drill holes according to the designed grouting holes and drainage holes using a drilling machine, and bury the grouting pipe (3.1) and the drainage pipe (3.2); when burying the grouting pipe (3.1) and the drainage pipe (3.2), it should be noted that each grouting pipe and the drainage pipe are arranged alternately to facilitate the diffusion of the slurry.

[0034] (II) System connection

[0035] The transport device (1) and the grouting device (2) are assembled in advance, and after the construction site is ready, the transport device (1) carries the grouting device (2) and transports it to the construction site.

[0036] Pipeline system (3): Grouting pipes (3.1) and drainage pipes (3.2) are buried in blocks in the tunnel bottom area, left wall area, right wall area, and tunnel top area; all grouting pipes (3.1) and drainage pipes (3.2) are installed at one time, but each area is grouted separately. After the grouting pipes (3.1) and drainage pipes (3.2) are buried, valves and joints are installed at the pipe openings. Grouting pressure gauges (5.1) and drainage pressure gauges (5.2) are installed at the pipe openings of the grouting pipes (3.1) and drainage pipes (3.2) respectively to measure the grouting pressure and drainage pressure; then, a conduit is used to connect the joint of a single grouting pipe (3.1) and the grouting device (2) slurry outlet pipe (2); a conduit is used to connect the joints of the drainage pipes (3.2) on both sides of the grouting pipe (3.1) and the drainage device (4);

[0037] A grouting pipe (3.1) and the drainage pipes (3.2) on both sides thereof form a construction cycle;

[0038] All conduits are made of threaded steel pipes to ensure tightness of the connection;

[0039] Drainage device (4): Use a conduit to connect the joint of the drainage pipe to the drainage pressure control box (4.5), install a drainage meter between the two, and ensure the sealing of the connection when connecting; the water pump (4.1) and the drainage pressure control box are connected by a conduit. The drainage conduit (4.2) is connected to the water outlet of the water pump (4.1) to drain the water to the outside of the tunnel. At the interface where the drainage conduit (4.2) connects to the water pump (4.1), a section of transparent plastic pipe (4.6) is connected to observe whether the slurry flows out; a valve (4.4) is installed after the transparent plastic pipe (4.6), and it is closed when the slurry flows out of the drainage outlet to prevent the slurry from flowing out.

[0040] The grouting pressure gauge (5.1) and the drainage pressure gauge (5.2) are connected to the intelligent pressure control device (5.3) by means of wires; the grouting pressure control box (2.4) and the drainage pressure control box (4.3) are connected to the intelligent pressure control device (5.3) by means of wires, so as to ensure that the intelligent pressure control device (5.3) performs intelligent monitoring of the grouting pressure and the drainage pressure according to the pressure value fed back from the system.

[0041] (III) Drainage grouting

[0042] For the grouting process, the parameters that need to be designed in advance are: pre-drainage pressure P1, pre-drainage time t1, grouting pressure P2 and continuous grouting time t2; pre-drainage pressure P1 is the pressure applied to the soil for drainage before grouting, pre-drainage time t1 refers to the duration of drainage in the soil before grouting, and grouting pressure P2 is the pressure applied by the grouting device during the grouting process. Under the action of pre-drainage pressure P1 and grouting pressure P2, an induction channel is formed inside the soil to achieve directional and quantitative grouting; in order to ensure the compactness of the grouting in the soil, the valve (3.5) should be closed after the slurry reaches the drainage area, and the soil is continuously grouted. The continuous grouting time is t2 to achieve the required grouting effect.

[0043] During construction of the present invention, drainage precedes grouting, and the grouting quantity measuring table (2.9) and the drainage quantity measuring table (4.7) need to be zeroed before each grouting. Before grouting, the negative pressure value in the intelligent pressure control device (5.3) is adjusted to P1, and the grouting pressure value is adjusted to P2. The intelligent pressure control device (5.3) automatically controls the grouting pressure control box (2.4) and the drainage pressure control box (4.3) to pressurize or depressurize the system according to the pressure values ​​fed back by the grouting pressure gauge (5.1) and the drainage pressure gauge (5.2). When the pressure values ​​of the grouting pressure gauge (5.1) and the drainage pressure gauge (5.2) exceed a certain pressure difference range between P2 and P1 (the range size is determined according to the slurry consistency, particle size and grading, and the grouting range size is determined according to the test results), the intelligent pressure control device (5.3) automatically controls the grouting pressure control box (2.4) and the drainage pressure control box (4.3) to perform pressure control on the system;

[0044] During grouting, the water pump (4.1) is first turned on to drain the saturated sand area for a continuous period of time t1; after negative pressure is formed in the local area, the grouting device is turned on to grout the saturated sand, so that the soil is split or an induced channel is generated in the induced direction, thereby achieving the effect of induced displacement grouting; when slurry is seen in the transparent plastic pipe (4.4), the valve corresponding to the drainage pipe is closed, and the grouting area is continued to be grouted for a continuous period of time t2 to ensure that the grouting area is fully grouted, and the grouting pump (2.2) and the valve corresponding to the grouting pipe are closed, and the data of the grouting volume measurement table (2.9) and the drainage volume measurement table (4.5) are recorded for grouting effect evaluation. After grouting is completed, the grouting pipe (3.1) and the drainage pipe (3.2) are filled with slurry. The grouting pipe (3.1) and the drainage pipe (3.2) can be pulled out and left in the grouting area to strengthen the strength of the grouting area. After grouting is completed, the equipment can be disassembled from the joint (3.4) to carry out the next cycle of construction; after the slurry solidifies, the valve, grouting pressure gauge and drainage pressure gauge can be disassembled.

[0045] During grouting, grouting of the tunnel bottom, both side walls, and the tunnel crown is completed in sequence to prevent less grout volume and lower strength at the tunnel crown due to the downward flow of the grout at the tunnel top.

[0046] (4). Grouting evaluation

[0047] After grouting in the present invention, the evaluation of the grouting effect in the grouting area is divided into: grouting density evaluation, water-stop effect evaluation, and reinforcement effect evaluation.

[0048] Grouting density evaluation:

[0049] The grouting density evaluation includes two parts: supplementary grouting evaluation and grouting effect evaluation.

[0050] The supplementary grouting evaluation is carried out after the grouting is completed, using the ratio of the grout volume C1 and the drainage volume C2 measured during the grouting process as the basis for whether supplementary grouting is needed. A set of grout volume C1 and drainage volume C2 is measured for each grouting, and the slurry filling rate When the slurry filling rate reaches w1, the grouting is considered qualified. When w < w1, the grouting density is considered unqualified, and the grouting area needs to be supplemented with grout.

[0051] The grouting effect evaluation is carried out using geophysical prospecting methods. After the slurry solidifies, the density of the grouting in the soil is detected using the self-invented detection equipment for grouting density in the water-rich area. The computer processes the data results accordingly to obtain the reinforcement effect image after the slurry diffusion in the grouting area, and evaluates the grouting effect.

[0052] Water-stop effect evaluation:

[0053] The evaluation is carried out using the sampling method. After the grouting area reaches an appropriate strength and before the excavation of the tunnel core soil area, the water-stop effect of the grouting area is evaluated. A small area is excavated at the heading face, and boreholes are drilled at the top, invert, and side walls of a cross-section in the grouting area to collect the water seepage volume at the boreholes for evaluating the grouting water-blocking effect. When the water seepage volume C3 at each location is less than the specified water seepage volume c, the water-stop effect is considered qualified. Otherwise, remedial measures need to be taken.

[0054] Reinforcement effect evaluation:

[0055] Using the specimens taken out in the water-stop effect evaluation, the strength of the specimens is tested experimentally. The average strength of the specimens is used as the basis for calculating the surrounding rock strength of the grouting area, and the reinforced surrounding rock strength of the grouting area is calculated. By comparing with the expected surrounding rock reinforcement strength, the grouting reinforcement effect is evaluated. When it reaches m% of the expected surrounding rock reinforcement strength, the surrounding rock reinforcement effect can be considered qualified.

[0056] (5). Tunnel excavation

[0057] After all indicators of grouting evaluation are qualified, the saturated sand in the core soil area of ​​the tunnel is excavated. During excavation, sufficient support is set up in the tunnel excavation area to prevent tunnel collapse during excavation.

[0058] Beneficial Effects

[0059] The present invention applies a new drainage induction and displacement grouting device and method to perform grouting on the tunnel surrounding rock area in the saturated sand area, thereby achieving the effect of reinforcing the tunnel surrounding rock. The beneficial effects of the present invention are as follows:

[0060] (1) Using the principles of drainage induction and displacement, directional grouting is carried out inside the saturated sand, forming the expected grouting reinforcement area inside the saturated sand, thereby achieving the purpose of strengthening the tunnel surrounding rock.

[0061] (2) An intelligent monitoring and control system (5) is used to automatically control the grouting pressure value and negative pressure value during the grouting process, thereby maintaining the uniformity of the grouting speed and achieving a good grouting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 Schematic diagram of grouting construction;

[0063] Figure 2 Schematic diagram of grouting vehicle;

[0064] Figure 3 Schematic diagram of the transport control device;

[0065] Figure 4 Schematic diagram of grouting device;

[0066] Figure 5 Schematic diagram of the piping system;

[0067] Figure 6 Schematic diagram of drainage device;

[0068] Figure 7 Schematic diagram of intelligent monitoring and control system;

[0069] Figure 8 Schematic diagram of pipeline layout at the tunnel face;

[0070] Fig. 9 Schematic diagram of the connection between the control room and the grouting device;

[0071] Fig.10 Schematic diagram of the monitoring and control principle of the intelligent monitoring and control system.

[0072] Figure annotation:

[0073] 1. Transportation control device, 2. Grouting device, 3. Pipeline system, 4. Drainage device, 5. Intelligent monitoring and control system.

[0074] Transport control device 1: 1.1, control room; 1.2, main body.

[0075] Grouting device 2: 2.1, slurry storage box, 2.2, grouting pump, 2.3, steel support, 2.4, grouting pressure control box, 2.5, grouting conduit, 2.6, slurry outlet pipe, 2.7, pressure sensor, 2.8, mixer, 2.9 grouting quantity measuring meter.

[0076] Pipeline system 3: 3.1, grouting pipe, 3.2, drainage pipe, 3.3.1, first conduit, 3.4.1, first joint, 3.5.1, first valve, 3.3.2, second conduit, 3.4.2, second joint, 3.5.2, second valve;

[0077] Drainage device 4: 4.1. water pump, 4.2. drainage conduit, 4.3. drainage pressure control box, 4.4. transparent plastic pipe, 4.5. drainage volume meter.

[0078] Intelligent monitoring and control system 5: 5.1. Grouting pressure gauge, 5.2. Drainage pressure gauge, 5.3. Intelligent pressure control device.

[0079] The present invention is specifically described by arranging the pipelines in a single grouting layer, and multiple layers of pipelines can be arranged according to actual conditions. The grouting pipes (3.1) and the drainage pipes (3.2) are alternately distributed. DETAILED DESCRIPTION

[0080] The present invention will be further described below in conjunction with examples, but the present invention is not limited to the following examples.

[0081] Example 1

[0082] The present invention mainly adopts the drainage induced grouting method, which forms a pressure difference inside the soil by draining water and applying grouting pressure, inducing directional flow of slurry and quantitative grouting to form the expected soil reinforcement area and range. After the slurry solidifies, it will coagulate the sand particles to form a surrounding rock reinforcement area with a certain strength, achieving the dual effects of water blocking and surrounding rock reinforcement. The specific implementation of the whole process of the present invention includes the following four links:

[0083] 1. Pipeline burial:

[0084] According to the corresponding grouting specifications, the following parameters are determined: the spacing S between the grouting hole and the drain hole, the diameter d of the grouting pipe and the drain pipe, the diffusion diameter D around the grouting pipe, and the number of layers w of the grouting pipe distribution. The present invention is specifically introduced with the distribution of two layers of grouting pipes. The present invention is only introduced with the construction of single-layer pipeline grouting and one-cycle grouting.

[0085] According to the condition of the soil in front of the tunnel, the positions of the grouting pipe (3.1) and the drainage pipe (3.2) are planned on the tunnel face. A drilling machine is used to drill holes on the tunnel face, and the drilling direction is ensured to have a certain angle with the horizontal plane. After the drilling is completed, the grouting pipe (3.1) and the drainage pipe (3.2) are alternately inserted into the holes to ensure that the slurry is evenly diffused in the soil during grouting. The grouting pipe (3.1) and the drainage pipe (3.2) are provided with small holes on the sides, and the slurry and water in the soil flow out and in from the small holes; each drainage pipe is wrapped with a layer of gauze to prevent the loss of sand and soil particles during the drainage process, forming a cavity area and affecting the strength of the surrounding rock.

[0086] 2. System connection

[0087] The transport device (1) and the grouting device (2) are assembled in advance before construction. After the construction site is ready, the transport device (1) directly transports the grouting device (2) to the construction site.

[0088] First, bury the grouting pipe (3.1) and the drainage pipe (3.2) in the soil. The drainage pipe (3.2) needs to be wrapped with a mesh before burying. The pre-buried grouting pipe (3.1) and the drainage pipe (3.2) are divided into four areas: the tunnel bottom area, the left wall area and the right wall area, and the tunnel top area. When installing the pipes, all the pipes in the entire grouting area are installed, but each area is grouted separately. After the grouting pipe (3.1) and the drainage pipe (3.2) are buried, the valve (3.5) and the joint (3.4) are installed on the grouting pipe (3.1) and the drainage pipe (3.2). Use a conduit (3.3) to connect the grouting device (2) The slurry outlet pipe (2.6) and the joint (3.4) at the grouting pipe (3.1), and use a conduit (3.3) to connect the drainage device (4) and the joints (3.4) at the drainage pipe (3.2) on both sides of the grouting pipe (3.1). The interfaces of all conduits (3.3) are made of threaded steel pipes to enhance the tightness of the connection.

[0089] The drainage device (4) mainly includes a water pump (4.1), a drainage conduit (4.2), a drainage pressure control box (4.3), a transparent plastic pipe (4.4) and a drainage volume meter (4.5). The conduit (3.3) is used to connect the joint (3.4) at the drainage pipe (3.2) and the drainage pressure control box (4.3), and the drainage volume meter (4.5) is installed at the joint between the two, and the sealing of the connection is ensured during the connection; the water pump (4.1) and the drainage pressure control box (4.3) are connected by the conduit (3.3). The drainage conduit (4.2) is connected to the water outlet of the water pump (4.1) to divert the water to a suitable area outside the tunnel. A transparent plastic tube (4.4) is connected to the interface where the drainage conduit (4.2) is connected to the water pump (4.1) to observe whether the slurry flows out of the drainage outlet; when the transparent plastic tube (4.4) sees that the slurry begins to flow out, the drainage pipe valve (3.5) is closed in time to prevent the slurry from flowing out.

[0090] After the grouting device 2, the pipeline system 3 and the drainage device 4 are connected, the grouting pressure gauge (5.1) and the drainage pressure gauge (5.2) are connected to the intelligent pressure control device (5.3) by using a wire. The grouting pressure control box (2.4) and the drainage pressure control box (4.3) are connected to the intelligent pressure control device (5.3) by using a wire to ensure that the intelligent pressure control device (5.3) performs intelligent monitoring of the grouting pressure and the drainage pressure according to the pressure value fed back from the system.

[0091] 3. Drainage grouting:

[0092] During grouting, the grouting is completed in the order of bottom invert grouting, side wall grouting, and tunnel vault grouting to prevent the risk of low strength of the tunnel top due to the loss of slurry at the tunnel top, which may cause voids at the tunnel top.

[0093] After the slurry storage box (2.1) is filled with slurry, the mixer (2.8) is immediately turned on to prevent the slurry from solidifying and affecting the grouting effect. Before each grouting, the grouting volume meter (2.9) and the drainage volume meter (4.5) need to be zeroed.

[0094] Before grouting, the negative pressure value in the intelligent pressure control device (5.3) is adjusted to P1, and the grouting pressure value is adjusted to P2. The intelligent pressure control device (5.3) automatically controls the grouting pressure control box (2.4) and the drainage pressure control box (4.3) to pressurize or depressurize the system according to the pressure values ​​fed back by the grouting pressure gauge (5.1) and the drainage pressure gauge (5.2).

[0095] When the pressure values ​​of the grouting pressure gauge (5.1) and the drainage pressure gauge (5.2) exceed a certain range of P2 and P1, the intelligent pressure control device (5.3) automatically controls the grouting pressure control box (2.4) and the drainage pressure control box (4.3) to control the pressure of the system.

[0096] Before grouting, the water pump (4.1) needs to be turned on in advance. The intelligent pressure control device (5.3) controls the drainage pressure control box (4.3) to adjust the pressure in the drainage device 4 according to the pressure value of the drainage pressure gauge (4.3), and controls the table value of the drainage pressure gauge (4.3) to be within a certain range of P1. The area around the drainage pipe (3.2) is drained under the negative pressure of P1, and a negative pressure area is formed around the drainage pipe (3.2). After the saturated sand is drained for time t1 under the negative pressure of P1, the grouting pump (2.2) is started, and the system starts grouting. During the grouting, the intelligent pressure control device (5.3) controls the grouting pressure control box (4.3) to adjust the pressure in the grouting device 2 according to the pressure value of the grouting pressure gauge (4.3), and controls the table value of the water pressure gauge (4.3) to be within a certain range of P2. During the entire grouting process, the intelligent pressure control device (5.3) continuously adjusts the pressure in the system according to the pressure values ​​fed back from the grouting pressure gauge (4.3) and the drainage pressure gauge (4.3). Ensure that the slurry is injected into the saturated sand at a uniform speed during the grouting process and that the grouting effect is reasonable.

[0097] When the grouting is completed until the slurry is visible in the transparent plastic tube (4.4), close the pump (4.1) and the drain pipe valve (3.5). Continue grouting the saturated sand area for a period of time t2 to ensure that the entire grouting area is fully grouted, and close the grouting pipe valve (3.5) and the grouting pump (2.2). Record the data on the grouting volume measurement table (2.9) and the drainage volume measurement table (4.5) for grouting effect evaluation. Disconnect the first conduit (3.3.1) from the grouting pipe (3.1) and the second conduit (3.3.2) from the drain pipe (3.2) to carry out the next cycle of construction. After the slurry in the grouting area solidifies, disassemble and clean the grouting pressure gauge (5.1), the drainage pressure gauge (5.2), the first valve (3.5.1), the first joint (3.4.1), the second valve (3.5.2) and the second joint (3.4.2).

[0098] After the grouting is completed, the grouting pipe (3.1) and the drainage pipe (3.2) remain in the grouting soil. After the slurry in the grouting pipe (3.1) and the drainage pipe (3.2) solidifies, it has good compressive strength and bending resistance, and has the effect of strengthening the strength of the grouting area.

[0099] 4. Grouting effect evaluation:

[0100] The evaluation indexes of the present invention include: grouting density evaluation, water-stopping effect evaluation and reinforcement effect evaluation. The grouting density evaluation includes grouting evaluation and grouting effect evaluation.

[0101] Grouting density evaluation:

[0102] Grout replenishment evaluation: Measure a set of grouting volume C1 and drainage volume C2 each time grouting is carried out. The grouting volume measured during the grouting process is C1, and the drainage volume is C2. The slurry filling rate When the slurry filling rate reaches w1, it is considered that the grouting is qualified. When w < w1, it is considered that the grouting density is unqualified, and the grouting area needs to be replenished with grout.

[0103] Grouting effect evaluation: After the slurry solidifies, use the independently invented detection equipment for grouting density in the water-rich area to scan the soil body in the grouting area, and use a computer to process the data results to obtain the reinforcement effect image after the slurry diffuses in the grouting area, and evaluate the grouting effect.

[0104] Water stop effect evaluation:

[0105] After the grouting area reaches an appropriate strength and before the excavation of the tunnel core soil area, excavate a small area at the heading face, drill and take samples at the top, invert, and side walls on a cross-section of the grouting area, collect the seepage volume at the drilling holes. When the seepage volume C3 at each location is less than the specified seepage volume c, it is considered that the water stop effect is qualified. Otherwise, remedial measures need to be taken.

[0106] Reinforcement effect evaluation:

[0107] The specimens taken out during the water stop effect evaluation are subjected to experimental tests, and the surrounding rock strength of the grouting area is calculated using the average strength of the specimens. When it reaches m% of the expected surrounding rock reinforcement strength, it can be considered that the surrounding rock reinforcement effect is qualified. Otherwise, reinforcement is required.

[0108] 5. Tunnel excavation:

[0109] After grouting, wait for the slurry in the grouting area to reach a certain strength, and the saturated sand and the slurry fuse to form a surrounding rock with a certain bearing capacity. After the density evaluation, water stop effect evaluation, and reinforcement effect evaluation of the grouting effect evaluation all reach the qualified standard, the tunnel section can be excavated and constructed.

[0110] The present invention includes but is not limited to the above content.

Claims

1. A pre-reinforcement device for a tunnel passing through saturated sand, characterized in that: It consists of five parts: transportation control device, grouting device, pipeline system, drainage device, and intelligent monitoring and control system; The transport control device includes the control room of the grouting device and the main body; in addition to the basic vehicle operating equipment, the control room also includes an alarm device, a control device and a display screen; The grouting device includes a slurry storage box, a grouting pump, a steel support, a grouting pressure control box, a grouting guide tube, a slurry outlet pipe, a pressure sensor, a mixer and a grouting quantity measuring meter; The pipeline system includes a grouting pipe, a drainage pipe, a first joint, a second joint, a first valve, and a second valve; The drainage device includes a water pump, a drainage conduit, a drainage pressure control box, a transparent plastic pipe, and a drainage volume meter; The intelligent monitoring and control system includes a grouting pressure gauge, a drainage pressure gauge, and an intelligent pressure control device; The pressure sensor in the grouting pressure control box is connected to the alarm device and display screen in the control room through wires; The mixer is placed on the top of the slurry storage tank and connected to the control device in the control room by wires; The grouting quantity meter is placed at the end of the grouting pipe and connected to the display screen in the control room by wires; The slurry outlet pipe is connected to the grouting pipe via the first conduit, the first joint and the first valve; The water inlet of the water pump is connected to the drainage pipe via the drainage pressure control box, the drainage meter, the second conduit, the second joint, the second valve in sequence, and the interfaces of each component are connected by threaded connection; The water outlet of the water pump is connected to a drainage conduit, and a section of transparent plastic pipe is arranged in the drainage conduit; A pressure sensor is installed at the bottom of the slurry storage box. The pressure sensor is connected to the alarm device and display screen in the control room through a wire. The pressure value fed back by the pressure sensor is displayed on the display screen in the control room. When the pressure value is lower than a certain value, the alarm device in the control room will sound an alarm. The mixer is placed inside the slurry storage box and connected to the control device in the control room through a wire. The stirring time and the stirring time interval are set in the control device in the control room to automatically prevent the slurry from solidifying during the grouting process. The slurry storage box is connected to the grouting pressure control box via a grouting pump. The grouting pressure in the grouting device is reasonably adjusted through the grouting pressure control box. The grouting pressure control box is provided with a slurry outlet pipe with a thread to ensure that it can be tightly connected with the first conduit. A grouting volume meter is provided on the slurry outlet pipe. The grouting volume meter is connected to the display screen in the control room through a wire. The grouting volume meter is zeroed before grouting. During the grouting process, the grouting volume meter will continuously monitor the grouting volume and feed it back to the display screen in the control room. After each grouting is completed, the single grouting volume is recorded for the final grouting evaluation. Each grouting pressure gauge is connected to the grouting pressure control box through an intelligent pressure control device, and each drainage pressure gauge is connected to the drainage pressure control box through an intelligent pressure control device. The grouting pressure gauge and drainage pressure gauge can dynamically monitor and measure the grouting pressure and drainage pressure during the grouting process, and timely feedback the pressure value to the intelligent pressure control device, which then controls the grouting pressure control box and the drainage pressure control box; A pump of suitable specifications is used in the drainage device to form negative pressure in the drainage device; the drainage conduit uses appropriate steel pipes to drain water; the drainage pressure control box adjusts the pressure in the drainage device and adjusts the reasonable negative pressure range to ensure the effect of grouting; a transparent plastic pipe is installed at the drainage outlet of the system, and the flow and consistency changes of the slurry are observed through the transparent plastic pipe to determine whether to stop grouting; when slurry flows through the transparent plastic pipe, the valve should be closed in time to prevent the loss of slurry; the drainage meter detects the drainage volume of a grouting during the grouting process, which is used to evaluate the grouting effect; Both the grouting pipe and the drainage pipe are flower tubes with holes on the side, and the ends are pointed and closed. During grouting, the slurry is evenly diffused from the small holes on the side of the grouting pipe into the saturated sand and soil. The drainage pipe is wrapped with gauze to prevent sand and soil particles around the drainage pipe from being lost or clogging the drainage pipe.

2. A pre-reinforcement device for a tunnel passing through saturated sand according to claim 1, characterized in that: The control room is located on the main vehicle body. In addition to performing basic operations on the vehicle, the control room also monitors the amount of slurry in the slurry storage tank and the amount of single grouting through the alarm device, control device and display screen, and controls the mixer.

3. A pre-reinforcement device for a tunnel passing through saturated sand according to claim 1, characterized in that: During the grouting process, a negative pressure area is formed around the drainage pipe, inducing the slurry discharged from the grouting pipe to flow into the negative pressure area, thus achieving directional grouting.

4. A pre-reinforcement device for a tunnel passing through saturated sand according to claim 1, characterized in that: Multiple grouting pipes and drainage pipes are set in the same tunnel. The grouting pipes and drainage pipes are arranged in a cross-spaced manner and the routes are arranged according to the required process.

5. A pre-reinforcement device for a tunnel passing through saturated sand according to claim 1, characterized in that: The first duct and the second duct are both made of steel pipes for conveying slurry and draining water; the first valve is placed at the entrance of the grouting pipe, mainly used to block the entrance of the grouting pipe; the second valve is placed at the entrance of the drainage pipe, mainly used to block the drainage pipe to prevent water in the soil before grouting and slurry in the soil after grouting from flowing in the opposite direction along the corresponding pipes.

6. A method for constructing a tunnel through saturated sand using a pre-reinforcement device according to any one of claims 1 to 5, characterized in that: The following steps are involved:

1. Buried pipelines According to the corresponding grouting specifications, the positions of the grouting holes and drainage holes for installing the grouting pipes and drainage pipes are designed. The parameters that need to be calculated in advance to determine the hole positions include: the spacing S between the grouting holes and the drainage holes, the diameters d of the grouting pipes and drainage pipes, the diffusion diameter D around the grouting pipes, and the number of layers w of the grouting pipe distribution; and the positions of the grouting holes and drainage holes are reasonably arranged according to the designed parameters; Use a drilling rig to drill holes according to the designed grouting holes and drainage holes, and bury the grouting pipes and drainage pipes; when burying the grouting pipes and drainage pipes, pay attention to the alternating arrangement of each grouting pipe and drainage pipe to facilitate the diffusion of the slurry; (II) System connection The transport control device and the grouting device are assembled in advance. When the construction site is ready, the transport control device carries the grouting device and transports it to the construction site; Pipeline system: bury the grouting pipes and drainage pipes in blocks in the tunnel bottom area, left wall area, right wall area, and tunnel top area; all the grouting pipes and drainage pipes are installed at one time, but each area is grouted separately; after the grouting pipes and drainage pipes are buried, valves and joints are installed at the pipe openings, and grouting pressure gauges and drainage pressure gauges are installed at the pipe openings of the grouting pipes and drainage pipes respectively to measure the grouting pressure and drainage pressure; then use a conduit to connect the joint of a single grouting pipe and the grouting device's grouting pipe; use a conduit to connect the joints of the drainage pipes on both sides of the grouting pipe and the drainage device; A grouting pipe and the drainage pipes on both sides of it constitute a construction cycle; All conduits are made of threaded steel pipes to ensure tightness of the connection; Drainage device: Use a conduit to connect the joint of the drainage pipe and the drainage pressure control box, install a drainage meter between the two, and ensure the sealing of the connection during connection; use a conduit to connect the water pump and the drainage pressure control box; connect the drainage conduit to the water outlet of the water pump to divert water to the outside of the tunnel; connect a section of transparent plastic pipe to the interface where the drainage conduit connects to the water pump to observe whether the slurry flows out; install a valve after the transparent plastic pipe, close it when observing the slurry flowing out of the drainage outlet to prevent the slurry from flowing out; Use wires to connect the grouting pressure gauge and drainage pressure gauge to the intelligent pressure control device; use wires to connect the grouting pressure control box and drainage pressure control box to the intelligent pressure control device to ensure that the intelligent pressure control device can intelligently monitor the grouting pressure and drainage pressure according to the pressure value fed back from the system; (III) Drainage grouting For the grouting process, the parameters that need to be designed in advance are: pre-drainage pressure , pre-drainage time , grouting pressure And the duration of grouting ;Pre-drainage pressure The pre-drainage time is the pressure applied to the soil before grouting. It refers to the duration of drainage of soil before grouting and the grouting pressure. It is the pressure applied by the grouting device during the grouting process. Grouting pressure Under the action of the induction channel formed inside the soil to achieve directional and quantitative grouting; in order to ensure the compactness of the grouting in the soil, the valve should be closed after the slurry reaches the drainage area, and the grouting in the soil should be continued for a continuous grouting time of The desired grouting effect can be achieved; During construction, drainage precedes grouting. Before each grouting, the grouting volume meter and drainage volume meter need to be zeroed. Before grouting, adjust the negative pressure value in the intelligent pressure control device to The grouting pressure is The intelligent pressure control device automatically controls the grouting pressure control box and the drainage pressure control box to pressurize or depressurize the system according to the pressure values ​​fed back by the grouting pressure gauge and the drainage pressure gauge; when the pressure values ​​of the grouting pressure gauge and the drainage pressure gauge exceed and When the pressure difference is within a certain range, the intelligent pressure control device automatically controls the grouting pressure control box and the drainage pressure control box to control the pressure of the system; When grouting, start the pump first and continue pre-draining the saturated sand area for a certain period of time. ; After negative pressure is formed in the local area, the grouting device is turned on to grout the saturated sand, and the soil is split or an induced channel is generated along the induced direction, which can achieve the effect of induced displacement grouting; when the slurry is seen in the transparent plastic pipe, the valve corresponding to the drainage pipe is closed, and the grouting area is continued for the grouting time , ensure that the grouting area is fully grouted, close the grouting pump and the valves corresponding to the grouting pipe, and record the data of the grouting volume measurement table and the drainage volume measurement table for grouting effect evaluation; after the grouting is completed, the grouting pipe and the drainage pipe are filled with slurry, and the grouting pipe and the drainage pipe are not pulled out, but left in the grouting area to strengthen the strength of the grouting area. After the grouting is completed, the equipment can be disassembled from the joint to carry out the next cycle of construction; after the slurry solidifies, the valve, grouting pressure gauge and drainage pressure gauge are disassembled; During grouting, the grouting should be completed in the order of tunnel bottom grouting, two side wall grouting, and tunnel vault grouting to prevent the grout at the top of the tunnel from flowing downward, resulting in less grout at the top of the tunnel and lower strength at the top of the tunnel; 4. Grouting evaluation After grouting, the grouting effect of the grouting area is evaluated in three ways: grouting density evaluation, water stop effect evaluation and reinforcement effect evaluation; Grouting density evaluation: The evaluation of grouting density includes two parts: grouting evaluation and grouting effect evaluation; Grouting evaluation is the grouting volume measured during the grouting process after the grouting is completed. and displacement The ratio of is used to evaluate whether grouting is needed; each grouting is performed to measure a group of grouting volume Displacement , slurry filling rate ; When the slurry filling rate reaches When When the grouting density is determined to be unqualified, the grouting area needs to be supplemented with grout; The evaluation of grouting effect is carried out by geophysical prospecting. After the grouting solidifies, the density of the grouting in the soil is tested by grouting density testing equipment. The data results are processed by computer to obtain the reinforcement effect image after the grouting area diffuses, and the grouting effect is evaluated. Water-stopping effect evaluation: Evaluation is carried out by sampling method; after the grouting area reaches the appropriate strength, before the core soil area of ​​the tunnel is excavated, the water-stopping effect of the grouting area is evaluated; a small area is excavated at the face, and drilling holes are taken at the top of a section of the grouting area, the invert, and the walls on both sides to collect the seepage volume at the boreholes for evaluating the grouting water-stopping effect; when the seepage volume at each location is , are both less than the specified water seepage volume c, the water stopping effect is deemed qualified; otherwise, remedial measures need to be taken; Evaluation of reinforcement effect: The strength of the samples taken out during the water-stopping effect evaluation is tested experimentally. The average strength of the samples is used as the basis for calculating the surrounding rock strength of the grouting area. The strength of the reinforced surrounding rock in the grouting area is calculated and compared with the expected surrounding rock reinforcement strength to evaluate the grouting reinforcement effect. When the expected surrounding rock reinforcement strength reaches m%, the surrounding rock reinforcement effect is considered qualified.

5. Tunnel excavation After all indicators of the grouting evaluation are qualified, the saturated sand in the core soil area of ​​the tunnel is excavated; during excavation, sufficient support is first set up in the tunnel excavation area to prevent tunnel collapse during excavation.

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