A deep burying device and burying method of pore water pressure gauge in soft soil area

Abstract

The present invention relates to a deep-layer buried device and method for a pore water pressure gauge in a soft soil area. The device comprises an outer tube, a casing, a compactor, a soil squeezer, a columnar connecting rod and a compactor handle; the outer tube is connected to the soil squeezer by a tying method; the casing and the outer tube are coaxially sleeved; a plurality of vertical guide grooves are evenly arranged on the inner wall of the casing along the circumference, a wire protection tube is also arranged on the inner wall of the casing, and a plurality of pore water pressure gauges are buried in the permeable material; the pore water pressure gauge is connected to a signal transmission line, and a plurality of limit blocks and wire reserved holes are arranged on the compactor; the limit blocks are buckled in the guide grooves of the casing. The burying method of the present invention comprises the following steps: hole forming, hole bottom sealing treatment, burying the pore water pressure gauge, hole sealing, repeated burying of the pore water pressure gauge and hole sealing, and data collection and analysis. The device of the present invention is simple, low-cost, and easy to operate. The survival rate of pore water pressure gauges buried in the field is high, the positioning is accurate, the sealing quality is good, and the data is reliable.

Description

Technical Field

[0001] The invention relates to a deep-layer burying device of a pore water pressure gauge in a soft soil area and a burying method thereof, belonging to the technical field of civil engineering. Background Art

[0002] In the field of civil engineering, it is often necessary to measure or monitor the changes in pore water pressure in the soil to study the stress, consolidation degree and foundation treatment effect of the soil. The pore water pressure value is an important data for scientific research and engineering projects, especially when it comes to the study of stress distribution and change law between soil and structure, consolidation and settlement calculation in foundation treatment, and stress monitoring of foundation pit retaining. A pore water pressure gauge is an instrument used to measure the changes in pore water pressure in the formation within a certain area and depth range under different construction conditions, so as to obtain the stress changes in the required soil layer section. The pore water pressure values ​​at different depths of the foundation soil layer can be obtained by burying pore water pressure gauges at different positions in the soil layer for testing. When burying, it is generally buried by drilling. However, since the soft soil foundation is relatively weak, it is easy to shrink the diameter when drilling. The mud used for mud wall protection will produce buoyancy on the pore water pressure meter and its signal transmission cable. At the same time, the field working environment is harsh and the burial method of the pore water pressure meter is not standardized, resulting in cumbersome installation and burial process of the pore water pressure meter, high burial cost, low survival rate, poor sealing quality, inaccurate burial position and other problems, making the measured data unable to truly reflect the actual pore water pressure of the measured soil layer, and the credibility is difficult to guarantee. All these problems directly affect the accuracy and reliability of the monitoring data, and may even cause wrong judgment and evaluation. Summary of the invention

[0003] The purpose of the present invention is to provide a deep-layer burying device and burying method of a pore water pressure gauge in a soft soil area in order to solve the problems existing in the current burying of pore water pressure gauges. In addition to achieving deep burying, the present invention also has compaction and hole sealing functions.

[0004] The technical solution adopted by the present invention is:

[0005] A deep-layer buried device for a pore water pressure gauge in a soft soil area, comprising an outer tube, a casing, a compactor, a soil squeezer, a columnar connecting rod and a compactor handle;

[0006] The outer tube is connected to the soil squeezer by a sleeve knot; the outer tube is used to protect the wall to prevent the hole from collapsing or shrinking; the soil squeezer is used to squeeze the soil to form a vertical borehole; the vertical borehole is filled with sealing materials and water-permeable materials;

[0007] The sleeve and the outer tube are coaxially sleeved, and both are hollow inside; a plurality of vertical guide grooves are evenly arranged on the inner wall of the sleeve along the circumferential direction, and a wire protection tube is also arranged on the inner wall of the sleeve;

[0008] A pore water pressure gauge is buried in the water-permeable material; the pore water pressure gauge is connected to a signal transmission line, and the wire protection tube is used to protect the signal transmission line;

[0009] The compactor is provided with a plurality of limit blocks and wire reserved holes; the limit blocks are buckled in the guide grooves of the sleeve to ensure that the movement of the compactor in the sleeve is piston movement; the wire reserved holes are for the signal transmission lines to pass through and eventually extend to the ground;

[0010] The columnar connecting rod is used to connect the compactor and the compactor handle. The compactor handle is tubular or has other shapes that are convenient for applying force. It is used to apply force to the compactor to compact the sealing material and the water-permeable material.

[0011] In the above technical solution, further, the outer tube is made of metal, the sleeve is made of metal or plastic, and each section of the outer tube or each section of the sleeve is connected by a thread.

[0012] Furthermore, the soil squeezer is a conical soil squeezer made of PVC plastic or metal, and is filled with materials such as clay soil so that its weight is equal to or close to that of the site soil, so that the settlement caused by the soil squeezer can be ignored.

[0013] Furthermore, the sealing material and the water-permeable material are poured in from above the outer tube.

[0014] Furthermore, the upper end of the cylindrical long rod is connected to the compactor handle through a thread, and the lower end of the cylindrical long rod is connected to the compactor through a thread. The length of the cylindrical long rod can be connected to multiple cylindrical connecting rods to enable the compactor to reach a set depth.

[0015] Furthermore, in order to facilitate the detachment of the soil squeezer from the outer tube when the outer tube is lifted later, lubricants such as vaseline and butter may be applied to the contact parts between the outer tube and the soil squeezer and between the outer tube and the sleeve.

[0016] Furthermore, the sealing material is clay or bentonite.

[0017] Furthermore, the water-permeable material may be medium sand or fine sand.

[0018] The present invention also provides a method for burying a pore water pressure gauge in a soft soil area. The method is implemented based on the above device, and the burying steps are as follows:

[0019] Step 1: Drilling. The soil squeezer and outer tube are placed at the designated location, and then the outer tube and soil squeezer are pushed by on-site excavators and other equipment to squeeze the soft soil around the soil squeezer and push it to the predetermined depth to form a vertical borehole. The outer tube is used to protect the wall to avoid shrinkage or collapse.

[0020] Step 2: Sealing the bottom of the hole. Pour a certain amount of sealing materials such as clay or bentonite into the outer tube, lift the outer tube to a certain height (greater than 10cm), and compact the sealing materials with a compactor.

[0021] Step 3: Bury the pore water pressure gauge. Pour a certain amount of permeable materials such as medium sand or fine sand into the outer tube and lift the outer tube. Use a compactor to compact it to a density of more than 90% (the first pore water pressure gauge buried depth). Place the pore water pressure gauge and wire protection tube into the casing. Lift the casing vertically and lower it vertically into the outer tube to the pore water pressure gauge buried depth.

[0022] Step 4: Sealing treatment. Pour a certain amount of permeable material into the casing and lift the casing to a certain height (the lifting height is the thickness of the permeable material), and compact it with a compactor to a density of more than 90%. Pour a certain amount of sealing material and permeable material into the casing in turn, lift the outer tube and casing, and compact them with a compactor in turn to a density of more than 90%. Fill the sealing material to the specified depth (i.e. the burial depth of the next pore water pressure gauge).

[0023] Step 5: Repeat the process of burying the pore water pressure gauge. Remove the casing and repeat steps 3 and 4 as many times as needed to bury the second and third pore water pressure gauges.

[0024] Step 6: Read the initial reading. When the pore water pressure meter is buried, remove the casing and outer tube, fill the hole with sealing material and compact it to the ground surface. After completion, connect the plug of each pore water pressure meter signal transmission line to the frequency meter and read the initial data of the pore water pressure meter.

[0025] In the above technical solution, further, the lifting height of the outer tube 1 or the sleeve 2 is equal to the height of the sealing material or the water-permeable material in the outer tube 1 or the sleeve 2, and the height of the sealing material is greater than 10 cm.

[0026] The beneficial effects of the present invention are:

[0027] The device of the present invention is simple, reusable and easy to use. There is no need to use a drilling rig to drill holes, which saves installation costs. During the burial process, the burial depth of the pore water pressure gauge can be well controlled, the burial depth is not limited, the positioning is accurate, and the sealing quality is good. In addition, during the burial process, the signal transmission line of the pore water pressure gauge is protected by the wire protection tube, is not easy to be damaged, and has a high survival rate. The test data is true and accurate, and has good regularity and correlation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of the present invention.

[0029] Figure 2It is a large-scale drawing of the soil squeezer of the present invention.

[0030] Figure 3 Schematic diagram of the cross section of the sleeve of the present invention.

[0031] Figure 4 It is a large-scale drawing of the handle of the compactor of the present invention.

[0032] Figure 5 It is a large-scale drawing of the compactor of the present invention.

[0033] Figure 6 It is a large-scale drawing of the pore water pressure gauge of the present invention.

[0034] Figure 7 This is a large-scale drawing of a single-section columnar connecting rod of the present invention.

[0035] Figure 8 This is a large-scale drawing of the signal transmission line protection tube of the present invention.

[0036] Fig. 9 It is a flow chart of burying the pore water pressure meter of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0038] A deep buried device for a pore water pressure gauge in a soft soil area, characterized in that it comprises an outer tube 1, a casing 2, a compactor 4, a soil squeezer 6, a columnar connecting rod 7, and a compactor handle 8. The outer tube 1, the compactor 4, the columnar connecting rod 7, and the compactor handle 8 are all made of metal, and the outer tube 1 is coaxially sleeved outside the casing 2; the bottom of the outer tube 1 is connected to the soil squeezer 6; the upper and lower ends of the columnar connecting rod 7 are respectively connected to the compactor handle 8 and the compactor 4 by threads; the casing 2 is made of metal or PVC plastic; a limit block 11 and a wire reserved hole 10 are provided on the compactor 4. A guide groove 12 is provided in the casing 2. A wire protection tube 9 is also provided on the inner wall of the casing 2, and a pore water pressure gauge 5 is buried in the permeable material. The pore water pressure gauge 5 is connected to a signal transmission line 3.

[0039] In the above device, each section of the outer tube 1 or each section of the casing 2 is connected by threading; the soil squeezer 6 is connected to the outer tube 1 by a caulking method. The soil squeezer 6 is a conical soil squeezer made of PVC plastic or metal, and is filled with a material with a weight equal to or close to the weight of the soil on the site. The outer tube 1 and the soil squeezer 6 are in place at a designated position, and the outer tube 1 and the soil squeezer 6 are pushed by the external force of an excavator or a bulldozer to squeeze the soft soil around the soil squeezer and push it to a predetermined depth to form a vertical borehole. The vertical borehole is filled with sealing materials and water-permeable materials. The sealing materials and water-permeable materials are poured from the top of the outer tube 1. The length of the columnar connecting rod 7 is adjustable and can be achieved by connecting multiple columnar connecting rods to each other. Lubricant is applied between the outer tube 1 and the soil squeezer 6 and the contact part between the outer tube 1 and the casing 2. The sealing material is clay or bentonite, and the water-permeable material is medium sand or fine sand.

[0040] A method for burying a pore water pressure gauge in a soft soil area is as follows: a certain amount of sealing materials such as clay or bentonite is poured into an outer tube 1, and the outer tube 1 is lifted to a certain height (the thickness of the sealing layer, generally more than 10 cm), and the sealing material is compacted with a compactor 4;

[0041] Next, pour a certain amount of permeable materials such as medium sand or fine sand into the outer tube 1, and compact it with a compactor 4 to a density of more than 90% (the bottom depth of the hole is the burial depth of the first pore water pressure gauge at this time); place the pore water pressure gauge 5 and the wire protection tube 9 in the casing 2, and the pore water pressure gauge signal transmission line 3 is passed through the wire protection tube 9. Lift the casing 2 vertically and lower it vertically into the outer tube 1 to a predetermined depth.

[0042] A certain amount of permeable material is poured into the casing 2 and the outer tube 1 and casing 2 are simultaneously lifted to a certain height (the lifting height is the thickness of the permeable material), and compacted to a density of more than 90% with a compactor 4. A certain amount of sealing material and permeable material is poured into the casing 2 in sequence, and the outer tube 1 and casing 2 are simultaneously lifted to a certain height (the lifting height is the thickness of the sealing material), and compacted to a certain density (more than 90%) with a compactor 4.

[0043] Remove casing 2. Repeat the above steps as needed to bury the second and third pore water pressure gauges.

[0044] After the pore water pressure meter 5 is buried, the casing 2 and the outer tube 1 are removed, and the sealing material is filled into the borehole and compacted to the ground surface. After completion, the plug of each pore water pressure meter signal transmission line 3 is connected to the frequency meter (not shown in the figure) to read the initial data of the pore water pressure meter.

[0045] The contents described in the embodiments of this specification are merely an enumeration of implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms described in the embodiments. The protection scope of the present invention also includes equivalent technical means that can be thought of by those skilled in the art based on the inventive concept.

Claims

1. A method for burying a pore water pressure gauge in a soft soil area, characterized in that: The invention is realized based on a deep-layer buried device for a pore water pressure gauge in a soft soil region, the device comprising an outer tube (1), a casing (2), a compactor (4), a soil squeezer (6), a columnar connecting rod (7) and a compactor handle (8); The outer tube (1) is connected to the soil squeezer (6) by means of a grommet; the outer tube (1) is used to protect the wall to prevent the hole from collapsing or shrinking; the soil squeezer (6) is used to squeeze the soil to form a vertical borehole; the vertical borehole is filled with a sealing material and a water-permeable material; The sleeve (2) and the outer tube (1) are coaxially sleeved, and both are hollow inside; a plurality of vertical guide grooves (12) are evenly arranged on the inner wall of the sleeve (2) along the circumferential direction, and a wire protection tube (9) is also arranged on the inner wall of the sleeve (2); A pore water pressure gauge (5) is buried in the water-permeable material; the pore water pressure gauge (5) is connected to a signal transmission line (3), and the wire protection tube (9) is used to protect the signal transmission line (3); The compactor (4) is provided with a plurality of limit blocks (11) and wire reserved holes (10); the limit blocks (11) are buckled in the guide grooves (12) of the sleeve (2) to ensure that the movement of the compactor (4) in the sleeve (2) is piston movement; the wire reserved holes (10) are for the signal transmission lines (3) to pass through; The columnar connecting rod (7) is used to connect the compactor (4) and the compactor handle (8), and the compactor handle (8) is used to apply force to the compactor (4), thereby compacting the sealing material and the water-permeable material; The steps of burying method are as follows: Step 1) Drilling: Connect and vertically push the outer tube (1) and the soil squeezer (6), squeeze the soft soil around the soil squeezer (6), and push it to a predetermined depth to form a vertical borehole; Step 2). Sealing the bottom of the hole: pour the sealing material into the outer tube (1) and raise the height of the outer tube (1), and compact the sealing material with a compactor (4); Step 3). Bury the pore water pressure gauge: pour the permeable material into the outer tube (1) and lift the outer tube (1), and compact it with a compactor (4) to a density of more than 90%; then place the pore water pressure gauge (5) and the wire protection tube (9) into the casing (2), vertically lift the casing (2), and vertically lower it into the outer tube (1) to the burial depth of the pore water pressure gauge; Step 4). Sealing treatment: pouring a water-permeable material into the casing (2) and raising the height of the casing (2), and then compacting it with a compactor (4) to a density of more than 90%; pouring a sealing material and a water-permeable material into the casing (2) in sequence, and raising the height of the outer tube (1) and the casing (2), and then compacting them with a compactor (4) in sequence to a density of more than 90%; filling the sealing material to the next pore water pressure gauge burial depth; Step 5). Repeat the process of burying the pore water pressure gauge: remove the casing (2), and repeat steps 3) and 4) as needed to bury the next pore water pressure gauge (5); Step 6). Reading the initial reading: After the pore water pressure meter (5) is buried, the casing (2) and the outer tube (1) are removed, the sealing material is filled into the borehole and compacted to the ground surface, and then the plug of the signal transmission line (3) of each pore water pressure meter (5) is connected to the frequency meter to read the initial data of the pore water pressure meter (5).

2. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The outer tube (1) is made of metal, and the sleeve (2) is made of metal or plastic. Each section of the outer tube (1) and each section of the sleeve (2) are connected by threads.

3. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The soil squeezer (6) is a conical soil squeezer made of PVC plastic or metal, and is filled with a material having a weight equal to or close to that of the soil on the site.

4. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The sealing material and the water-permeable material are poured in from above the outer tube (1).

5. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The upper end of the columnar connecting rod (7) is connected to the compactor handle (8) via a thread, and the lower end is connected to the compactor (4) via a thread; the length of the columnar connecting rod (7) is adjustable, which is achieved by connecting a plurality of columnar connecting rods to each other.

6. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The contact parts between the outer tube (1) and the soil squeezer (6) and between the outer tube (1) and the sleeve (2) are coated with lubricant.

7. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The sealing material is clay or bentonite.

8. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The water-permeable material is medium sand or fine sand.

9. The method for burying a pore water pressure gauge in a soft soil area according to claim 1, characterized in that: The lifting height of the outer tube (1) or the sleeve (2) is equal to the height of the sealing material or the water-permeable material in the outer tube (1) or the sleeve (2), and the height of the sealing material is greater than 10 cm.

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