Device for measuring deep settlement of soil body right above shield tunnel

Abstract

The utility model discloses a device for measuring the deep settlement of a soil body right above a shield tunnel, which comprises the ground, a measuring hole arranged on the ground, a measuring rod arranged in the measuring hole, a cement weighting block fixedly connected to the bottom of the measuring rod, a sleeve sleeved on the measuring rod, and the bottom end of the sleeve extending into the cement weighting block. By adopting the device for measuring the deep settlement of the soil body right above the shield tunnel, the sealing performance of the measuring hole is ensured, the sensitivity of settlement feedback is improved, and the ground is prevented from being punctured by shield pressure.

Description

Technical Field

[0001] The utility model belongs to the field of shield tunnel construction. Specifically, the utility model relates to a device for measuring the deep settlement of soil above a shield tunnel. Background Technique

[0002] Due to the safe and efficient construction characteristics of shield tunnel technology, it is increasingly widely used in the utilization of urban underground space. Due to the complex surrounding environment in cities, with crisscrossed ground and underground buildings and structures, higher requirements are imposed on the control of ground settlement during tunnel construction. In order to timely grasp the ground settlement changes and facilitate the adoption of emergency measures to control the settlement impact, a deep settlement monitoring device is used to monitor the deformation deep in the ground. The commonly used deep settlement monitoring methods include the deep benchmark level method, the magnetic ring settlement gauge method, and the fixed rod method. Since shield construction needs to be advanced under a certain pressure, these three methods do not consider the sealing between the measuring device and the soil of the hole wall. Drilling a deep hole is equivalent to weakening the overburden pressure on the top of the tunnel, which is likely to cause the shield pressure to break through the measuring hole, resulting in the inability to maintain a stable shield construction pressure. At the same time, after breakthrough, foam or mud will emerge on the ground, which has a greater impact on the surrounding environment.

[0003] The utility model patent with the publication number of CN211737214U was published on October 23, 2020, with the name of a shield tunnel segment settlement monitoring and alarm system, including a monitoring system and an alarm system; the monitoring system includes a pore water pressure sensor, a first displacement sensor, and a data acquisition instrument; the pore water pressure sensor is arranged in the soil at different positions of the tunnel; the first displacement sensor is arranged between the outer surface of the tunnel segment and the soil outside the segment; the pore water pressure sensor and the first displacement sensor are connected to the data acquisition instrument by wired or wireless means; the alarm system includes an alarm controller, an alarm, and an alarm map for displaying the position of the abnormal area; the alarm controller receives signals from the monitoring system and outputs signals to the alarm and the alarm map. This shield tunnel segment settlement monitoring and alarm system cannot solve the above technical problems. Content of the Utility Model

[0004] The purpose of the utility model is to provide a device for measuring the deep settlement of soil above a shield tunnel that ensures the sealing of the measuring hole, improves the sensitivity of settlement feedback, and avoids the shield pressure from breaking through the ground in view of the deficiencies of the prior art.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0006] The device for measuring the deep settlement of soil above a shield tunnel includes the ground. A measuring hole is provided on the ground. A measuring rod is arranged in the measuring hole. A cement weighting block is fixedly connected to the bottom of the measuring rod. A casing is sleeved on the measuring rod. The bottom end of the casing extends into the cement weighting block. A backfill layer is arranged in the measuring hole outside the casing and the cement weighting block.

[0007] A pipe groove is provided in the middle of the cement weighting block. The bottom end of the measuring rod is fixedly connected to the cement weighting block in an anchored manner, and the bottom end of the casing extends into the pipe groove.

[0008] The backfill layer includes a first fine sand layer, a medium-coarse sand layer, quick-drying cement, and a second fine sand layer. The first fine sand layer, the medium-coarse sand layer, the quick-drying cement, and the second fine sand layer are filled in the measuring hole in sequence from bottom to top. The quick-drying cement is fixedly connected to the casing.

[0009] The quick-drying cement is lower than the top end of the casing, and the top pipe orifice of the casing is sealed.

[0010] The top end of the casing is lower than the top end of the measuring rod, the top end of the measuring rod is lower than the ground surface, the first fine sand layer is higher than the cement weighting block, and the top end of the second fine sand layer is lower than the top end of the measuring rod.

[0011] The casing includes a joint, and the casing is of a segmented structure.

[0012] The measuring rod is a threaded steel bar, and the casing is made of PVC.

[0013] The technical effect of the present utility model is as follows: By using the deep soil layer settlement measuring device above the shield tunnel of the present utility model, the self-weight of the cement weighting block and the pressure of the surrounding soil on it are used to pull the measuring rod to sink. At the same time, a casing is provided to separate the soil from the measuring rod, reducing the resistance of the measuring rod to sink, thereby improving the sensitivity of settlement feedback. The casing is inserted into the cement weighting block, and the cement weighting block itself is impermeable, blocking the channel for underground muddy water or shield foam to seep out along the gap between the casing and the measuring rod, solving the problem that the current deep settlement measurement method cannot ensure the tightness of the measuring hole; at the same time, sand, soil, and quick-drying cement are backfilled in the space between the casing and the measuring hole to seal the drilling space, thereby avoiding the shield pressure from breaking through the ground surface and avoiding adverse effects on the surrounding environment. Description of the Drawings

[0014] This specification includes the following drawings, and the shown contents are respectively:

[0015] Figure 1 It is a structural schematic diagram of the deep soil layer settlement measuring device above the shield tunnel of the present utility model;

[0016] Figure 2 It is a backfill schematic diagram of the measuring hole of the present utility model;

[0017] The markings in the figure are: 1, measuring hole; 2, measuring rod; 3 joint; 4, casing; 5, cement weighting block; 6, first fine sand layer; 7, quick-drying cement; 8, medium-coarse sand layer; 9, second fine sand layer; 10, ground surface; 11, pipe groove. Detailed Embodiment

[0018] The following will further describe the specific implementation manners of the present utility model in detail with reference to the accompanying drawings through the description of the embodiments, aiming to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concept and technical solutions of the present invention and facilitate its implementation.

[0019] As Figure 1 and Figure 2 shown, the deep soil settlement measurement device above the shield tunnel includes the ground 10. A measurement hole 1 is provided on the ground 10. A measuring rod 2 is provided in the measurement hole 1. A cement weighting block 5 is fixedly connected to the bottom of the measuring rod 2. A sleeve 4 is sleeved on the measuring rod 2. The bottom end of the sleeve 4 extends into the cement weighting block 5. A backfill layer is provided outside the sleeve 4 and the cement weighting block 5 in the measurement hole 1.

[0020] The measurement hole 1 is located directly above the shield tunnel. The cement weighting block 5 can reflect the settlement of the soil below it. The measuring rod 2 is fixedly connected to the cement weighting block 5, and the movement reaction of the cement weighting block 5 can be transferred to the measuring rod 2, facilitating the observation by the staff. The sleeve 4 is used to separate the soil and the measuring rod 2, reducing the resistance of the measuring rod 2 to sink. The backfill layer is used to seal the measurement hole 1 to prevent the shield pressure from breaking through the ground 10. To prevent the shield mud or foam from flowing out of the ground 10 along the gap between the sleeve 4 and the measuring rod 2, the bottom end of the sleeve 4 is extended into the cement weighting block 5.

[0021] As Figure 1 shown, a pipe groove 11 is provided in the middle of the cement weighting block 5. The bottom end of the measuring rod 2 is anchored to the cement weighting block 5. The bottom end of the sleeve 4 extends into the pipe groove 11. The cement weighting block 5 is made of quick-drying cement and is a cylinder with a diameter of 80 mm and a height of 200 mm. The measuring rod 2 and the bottom of the sleeve 4 are cast with the cement weighting block 5. The sleeve 4 can be pulled out before the cement solidifies to form a pipe groove 11 for placing the bottom of the sleeve 4. The measuring rod 2 is anchored into the cement weighting block 5, and 100 mm at the bottom of the measuring rod 2 is directly fixedly connected to the cement weighting block 5. There is a space for the pipe groove 11 between the upper part of the measuring rod 2 and the cement weighting block 5. After the cement weighting block 5 solidifies, the bottom end of the sleeve 4 can be inserted into the pipe groove 11. The cement weighting block 5 is not fixedly connected to the sleeve 4 to seal the gap between the sleeve 4 and the measuring rod 2.

[0022] As Figure 2As shown, the backfill layer includes a first fine sand layer 6, a medium-coarse sand layer 8, quick-drying cement 7, and a second fine sand layer 9. The first fine sand layer 6, the medium-coarse sand layer 8, the quick-drying cement 7, and the second fine sand layer 9 are filled in the measuring hole 1 in sequence from bottom to top. The quick-drying cement 7 is fixedly connected to the casing 4. The space between the measuring device and the hole wall is backfilled. First, fine sand is backfilled at the bottom, drilling muck or medium-coarse sand is backfilled in the middle, and quick-drying cement 7 is backfilled at the upper part. Fine sand is backfilled upward from the quick-drying cement 7. Among them, the quick-drying cement 7 will consolidate the upper soil layer and the casing 4. When the deep soil layer settles, the settlement of the upper soil layer will lag, and the settlement of the deep soil layer can be accurately reflected by the measuring rod 2. The medium-coarse sand can quickly occupy the side hole space and improve the measuring efficiency.

[0023] As Figure 2 shown, the quick-drying cement 7 is lower than the top end of the casing 4, and the top pipe orifice of the casing 4 is sealed. The liquid level of the quick-drying cement 7 needs to be lower than the top end of the casing 4 to prevent the quick-drying cement 7 from contacting the measuring rod 2 and causing the measuring rod 2 to be consolidated with the casing 4. The top pipe orifice of the casing 4 is sealed to prevent cement from entering the casing 4 during backfilling and causing the casing 4 and the measuring rod 2 to be consolidated, ensuring that the relative movement between the casing 4 and the measuring rod 2 is unobstructed.

[0024] As Figure 2 shown, the top end of the casing 4 is lower than the top end of the measuring rod 2, the top end of the measuring rod 2 is lower than the ground 10, the first fine sand layer 6 is higher than the cement weighting block 5, and the top end of the second fine sand layer 9 is lower than the top end of the measuring rod 2. After the measuring hole 1 is drilled to the specified depth, the measuring device is lowered into place. The bottom of the casing 4 needs to be inserted into the bottom of the pipe slot 11, and the top height is 100 mm lower than the top of the measuring rod 2, and the top of the measuring rod 2 is 20 mm lower than the ground 10. The above structure is used to ensure that the top end of the measuring rod 2 is exposed, ensuring that it has enough measurable space. The cement weighting block 5 is surrounded by the first fine sand layer 6, and it will not affect the settlement movement of the cement weighting block 5.

[0025] As Figure 1 and Figure 2 shown, the casing 4 includes a joint 3, and the casing 4 is a segmented structure. The outer diameter of the casing 4 is 24 mm, and the length of the casing 4 can be extended through the joint 3 to realize the use of measuring holes 1 at different depths.

[0026] The measuring rod 2 is a threaded steel bar, and the material of the casing 4 is PVC. The measuring rod 2 is a threaded steel bar with a diameter of 18 mm. The materials of the measuring rod 2 and the casing 4 are easily available, which is beneficial to reducing costs.

[0027] Example: As Figure 1The deep settlement measurement device shown includes a measurement hole 1, a measuring rod 2, a joint 3, a casing 4, and a cement weight 5. The diameter of the measurement hole 1 is d3, the diameter of the measuring rod 2 is d1 = 18 mm, the diameter of the casing 4 is d2 = 24 mm, and the diameter of the cement weight 5 is d4 = 80 mm. The depth of the measurement hole 1 is L1, the height of the cement weight 5 is L2 = 200 mm, the depth of the pipe groove 11 of the casing 4 is L4 = 100 mm, the anchoring and bonding length between the measuring rod 2 and the cement weight 5 is L3 = 100 mm, the distance from the top of the measuring rod 2 to the top of the casing 4 is L5 = 100 mm, and the height L6 from the top of the measuring rod 2 to the ground 10 is 10.

[0028] As Figure 2 shown, the backfill of the measurement hole 1 includes upper fine sand backfill, quick-drying cement backfill 7, medium and coarse sand backfill 8, lower fine sand backfill, and ground 10. The distance from the top of the upper fine sand backfill to the ground 10 is L7, the distance from the top of the quick-drying cement backfill 7 to the top of the casing 4 is L8, the height of the quick-drying cement backfill 7 is L9, and the height of the lower fine sand backfill is L10.

[0029] The specific implementation process is as follows:

[0030] Step 1: Prepare a measuring rod 2 and a casing 4 of appropriate lengths according to the required burial depth of the measurement hole 1. Pour a cement weight 5 at the bottom of the measuring rod 2 with quick-drying cement. The cross-section of the weight is circular. The diameter d4 of the cement weight 5 is 80 mm. The diameter d3 of the measurement hole 1 should be greater than the diameter d4 of the cement weight 5. The height L2 of the weight is 200 mm. The upper part of the embedded part is the pipe groove 11 of the casing 4 with a depth L4 = 100 mm to facilitate the insertion of the casing 4. Before the cement solidifies, the casing 4 needs to be inserted and then pulled out to leave space for the casing 4. The anchoring and bonding length between the measuring rod 2 and the cement weight 5 is L3 = 100 mm. The distance from the top of the measuring rod 2 to the top of the casing 4 is L5 = 100 mm. The height L6 from the top of the measuring rod 2 to the ground 10 is not less than 20 mm.

[0031] Step 2: After the strength of the cement weight 5 is sufficient to anchor the measuring rod 2, connect the casing 4 in sections. The casing 4 is connected through a joint 33. The connection length of the casing 4 should ensure that 100 mm at the top of the measuring rod 2 is not covered by the casing 4. The bottom of the casing 4 is inserted into the groove of the cement weight 5.

[0032] Step 3: Drill a hole according to the determined depth L1 of the deep hole. When the formation stability is good, the hole can be directly drilled with a drill rod. When the formation stability is poor, the casing 4 can be used for pipe-following drilling. After the hole is formed, the drill rod is pulled out, and the deep settlement measurement device is lowered.

[0033] Step 4: Lower the fabricated deep settlement measurement device. Before lowering, ensure that the strength of the cement weight 5 is sufficient to anchor the steel bars. At the same time, ensure that the length of the measuring rod 2 matches the depth of the borehole. After lowering in place, the distance L6 from the top of the measuring rod 2 to the ground 10 shall not be less than 20 mm.

[0034] Step 5: Backfill the borehole. During the backfilling process, seal the top nozzle of the casing 4 to prevent cement from entering. First, backfill the lower part with fine sand, and the height L10 of the lower fine sand backfill shall not be less than 1000 mm. Then backfill with medium and coarse sand until the filling height is 1000 mm from the top nozzle of the casing 4. Then let it stand for 2 - 3 days and then backfill with quick-drying cement 7. The liquid level of the quick-drying cement 7 shall not exceed the top nozzle of the casing 4, and the distance L8 from the top of the backfilled quick-drying cement 7 to the top of the casing 4 shall not be less than 50 mm. After the quick-drying cement 7 solidifies, fine sand can be filled on it, and the distance L7 from the top of the upper fine sand backfill to the ground 10 shall not be less than 100 mm, leaving enough measurable space.

[0035] The measurement principle is as follows: When ground loss occurs during the shield tunneling process, causing the soil below the cement weight 5 to subside, the soil pressure above the cement weight 5 acts on the cement weight 5, pressing the cement weight 5 and the measuring rod 2 downward, causing the measuring rod 2 to sink. Due to the upper quick-drying cement 7, the casing 4 is consolidated with the upper soil layer, and the reaction will lag. Since the measuring rod 2 is anchored to the cement weight 5, the measuring rod 2 sinks together with the cement weight 5, thereby achieving high sensitivity of the deep settlement reaction. Since the lower part of the casing 4 is embedded in the cement weight 5, although the cement weight 5 sinks relative to the casing 4, when the settlement amount is within 100 mm, it will not cause the bottom of the casing 4 to come out of the cement weight 5, thus ensuring that the shield mud or foam will not flow out of the ground 10 along the gap between the casing 4 and the measuring rod 2; when the settlement amount exceeds 100 mm, it indicates that the ground loss is large. At this time, the deep measurement hole 1 is meaningless and can be sealed, and measures need to be taken to compensate for the ground loss.

[0036] For the deep settlement measurement device of the soil mass directly above the shield tunnel, the self-weight of the cement weight 5 and the pressure of the surrounding soil on it are used to pull the measuring rod 2 to sink. At the same time, the casing 4 is set to separate the soil from the measuring rod 2, reducing the resistance of the measuring rod 2 to sink, thereby improving the sensitivity of the settlement feedback. The casing 4 is inserted into the cement weight 5. The cement weight 5 itself is impermeable, blocking the channel for the underground mud or shield foam to seep out along the gap between the casing 4 and the measuring rod 2, solving the problem that the current deep settlement measurement method cannot ensure the sealing of the measurement hole 1; at the same time, the space between the casing 4 and the measurement hole 1 is backfilled with sand, soil and quick-drying cement 7 to seal the borehole space, thus avoiding the shield pressure from piercing the ground 10 and avoiding adverse effects on the surrounding environment.

[0037] The above has made an exemplary description of the present utility model in conjunction with the accompanying drawings. Obviously, the specific implementation of the present utility model is not limited by the above-mentioned manner. As long as various non-substantive improvements are made by adopting the method concept and technical solution of the present utility model; or without improvement, the above-mentioned concept and technical solution of the present utility model are directly applied to other occasions, all are within the protection scope of the present utility model.

Claims

1. A device for measuring the deep settlement of soil mass directly above a shield tunnel, characterized in that: It includes a ground (10) with a measuring hole (1) provided thereon. A measuring rod (2) is arranged in the measuring hole (1). A cement weight (5) is fixedly connected to the bottom of the measuring rod (2). A sleeve (4) is sleeved on the measuring rod (2). The bottom end of the sleeve (4) extends into the cement weight (5). A backfill layer is arranged outside the sleeve (4) and the cement weight (5) in the measuring hole (1).

2. The deep soil settlement measurement device above the shield tunnel according to claim 1, characterized in that: A pipe groove (11) is arranged in the middle of the cement weight (5). The bottom end of the measuring rod (2) is anchored and connected to the cement weight (5). The bottom end of the sleeve (4) extends into the pipe groove (11).

3. The deep soil settlement measuring device above the shield tunnel according to claim 2, characterized in that: The backfill layer includes a first fine sand layer (6), a medium and coarse sand layer (8), quick-drying cement (7) and a second fine sand layer (9). The first fine sand layer (6), the medium and coarse sand layer (8), the quick-drying cement (7) and the second fine sand layer (9) are filled in the measuring hole (1) in sequence from bottom to top. The quick-drying cement (7) is fixedly connected to the sleeve (4).

4. The device for measuring the deep settlement of the soil mass directly above a shield tunnel according to claim 3, wherein: The quick-drying cement (7) is lower than the top end of the sleeve (4). The top pipe orifice of the sleeve (4) is sealed.

5. The deep soil settlement measuring device above the shield tunnel according to claim 4, characterized in that: The top end of the sleeve (4) is lower than the top end of the measuring rod (2). The top end of the measuring rod (2) is lower than the ground (10). The first fine sand layer (6) is higher than the cement weight (5). The top end of the second fine sand layer (9) is lower than the top end of the measuring rod (2).

6. The deep soil settlement measurement device above the shield tunnel according to any one of claims 1-5, characterized in that: The sleeve (4) includes a joint (3). The sleeve (4) is of a segmented structure.

7. The deep soil settlement measurement device above the shield tunnel as described in claim 1, wherein: The measuring rod (2) is a threaded steel bar. The material of the sleeve (4) is PVC.

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