A static pressure type pore water pressure testing device and testing method

Abstract

A static pressure type pore water pressure testing device includes a static cone penetrometer, a static cone penetration rod, and a pore water pressure gauge device. The static cone penetration rod is installed on the static cone penetrometer, and the lower end of the static cone penetration rod is connected to the pore water pressure gauge device. The pore water pressure gauge device includes a pore water pressure gauge, a static cone penetration rod connecting sleeve, a penetration protection pipe, and dry sand. The static cone penetration rod connecting sleeve and the penetration protection pipe are sleeved outside the pore water pressure gauge in an up-and-down arrangement and the three can move axially relative to each other. The upper end of the static cone penetration rod connecting sleeve is connected to the static cone penetration rod, and the penetration protection pipe is filled with dry sand that can be extruded upward to cover the surface of the pore water pressure gauge body. A pore water pressure testing method using this device is also proposed. The present invention avoids the mud generated during drilling and burying, is environmentally hygienic, has a simple device structure, is convenient to operate, has high testing accuracy, saves time and effort, and is both economical and environmentally friendly.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering testing, and particularly relates to a static pressure type pore water pressure testing device and a testing method. Background Art

[0002] When it is necessary to understand the pore water pressure in the stratum during engineering design and construction, a pore water pressure gauge is often buried in the stratum. The main testing method is to first form a hole with a drill rig, then lower the pore water pressure gauge, and then backfill. The traditional testing method has the following disadvantages: 1. When burying, it is necessary to form a hole in advance. A drill rig is used to pre-drill a hole, and then the pore water pressure gauge testing equipment is lowered and backfilled. The whole process is relatively cumbersome and time-consuming; 2. After the pore water pressure gauge is placed, it is necessary to fill in sand-like filter materials and sealing clay, etc., which is time-consuming and laborious, and will damage the pore water pressure gauge. It is difficult to ensure the water-stop sealing effect of the pore water pressure gauge, resulting in low test accuracy; 3. A large amount of mud will be generated during the hole-forming process of the drill rig, polluting the environment; 4. The pore water pressure gauge cannot be recovered after being buried, which is neither economical nor environmentally friendly; 5. The testing method is relatively complex, and it is difficult to ensure the burial depth and the accuracy of the testing equipment. Summary of the Invention

[0003] In view of the above problems, the present invention provides a static pressure type pore water pressure testing device and a testing method.

[0004] The object of the present invention can be achieved by the following technical solutions: A hydrostatic pore water pressure testing device includes a static cone penetrometer, a static cone penetration rod, and a pore water pressure gauge device. The static cone penetrometer is installed with the static cone penetration rod, and the lower end of the static cone penetration rod is connected to the pore water pressure gauge device. The pore water pressure gauge device includes a pore water pressure gauge, a static cone penetration rod connecting sleeve, a penetration protection tube, and dry sand. The static cone penetration rod connecting sleeve and the penetration protection tube are sleeved outside the pore water pressure gauge in an up-and-down arrangement, and the pore water pressure gauge, the static cone penetration rod connecting sleeve, and the penetration protection tube can move axially relative to each other. The pore water pressure gauge includes a pore water pressure gauge connecting pipe and a pore water pressure gauge body connected up and down. The upper end of the pore water pressure gauge connecting pipe is provided with an upper connector and an upper rubber sealing ring, and the lower end of the pore water pressure gauge body is provided with a lower connector and a lower rubber sealing ring. The upper end of the static cone penetration rod connecting sleeve is connected to the lower end of the static cone penetration rod, and the lower end of the static cone penetration rod connecting sleeve is provided with an upper connecting support. The upper connecting support is arranged below the upper connector and the upper rubber sealing ring and limits the axial downward movement of the upper connector and the upper rubber sealing ring. The upper rubber sealing ring is arranged between the upper connecting support and the upper connector. The penetration protection tube includes an upper penetration protection tube, a lower penetration protection tube, and a penetration head connected in sequence from top to bottom. The upper end of the upper penetration protection tube is provided with a lower connecting support. The lower connecting support is arranged above the lower connector and the lower rubber sealing ring and limits the axial upward movement of the lower connector and the lower rubber sealing ring. The lower rubber sealing ring is arranged between the lower connecting support and the lower connector. Among them, dry sand is filled between the lower connecting support and the lower rubber sealing ring in the penetration protection tube, and a hole groove structure for the dry sand to be extruded upward out of the penetration protection tube is provided at the lower connecting support.

[0005] Further, both the upper connecting support and the lower connecting support are conical. Further still, the bottom surface of the upper connecting support is flush with the lower end pipe orifice of the static cone penetration rod connecting sleeve, and the outer diameter of the bottom surface of the upper connecting support is larger than the outer diameter of the static cone penetration rod connecting sleeve. The bottom surface of the lower connecting support is flush with the upper end pipe orifice of the upper penetration protection tube, and the outer diameter of the bottom surface of the lower connecting support is larger than the outer diameter of the upper penetration protection tube.

[0006] Further, the hole groove structure is: a plurality of protrusions are circumferentially and uniformly arranged on the inner wall of the lower connecting support. A plurality of axially extending holes are circumferentially and uniformly arranged between the inner wall of the lower connecting support, the plurality of protrusions, and the outer wall of the pore water pressure gauge. The holes are for the dry sand to be extruded upward out of the penetration protection tube.

[0007] Further, a cable is connected to the upper end of the pore water pressure gauge body, and the cable is led out from the pore water pressure gauge connecting pipe, the static cone penetration rod connecting sleeve, and the static cone penetration rod.

[0008] Further, the penetration head is conical.

[0009] Furthermore, the lower end of the pore water pressure gauge connecting pipe is threadedly connected to the upper end of the pore water pressure gauge body, the upper end of the CPT rod connecting sleeve is threadedly connected to the lower end of the CPT rod, and the lower end of the upper penetration protection pipe is threadedly connected to the upper end of the lower penetration protection pipe.

[0010] A pore water pressure testing method using the above-mentioned static pressure type pore water pressure testing device includes the following steps:

[0011] (1) Set the static cone penetrometer on the test ground, and gradually press the CPT rod into the test formation through the static cone penetrometer until the required burial depth is reached;

[0012] (2) Slowly lift the CPT rod through the static cone penetrometer, lift the pore water pressure gauge out of the penetration protection pipe, and control the lifting length so that the pore water pressure gauge body is exposed to contact with the test formation for pore water pressure testing;

[0013] (3) After the test, lift the CPT rod and the pore water pressure gauge device out together through the static cone penetrometer.

[0014] Furthermore, in step (2), the CPT rod connecting sleeve and the upper connecting support are lifted together with the CPT rod. During the lifting process, the upper connecting support drives the upper connector to move upward, thereby lifting the pore water pressure gauge out of the penetration protection pipe.

[0015] Furthermore, in step (2), during the process of lifting the pore water pressure gauge out of the penetration protection pipe, the dry sand in the penetration protection pipe is extruded upward from the hole groove by the lower rubber sealing ring and covers the surface of the pore water pressure gauge body.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] (1) Modify the traditional pore water pressure gauge device, connect it to the CPT rod, and use the static cone penetrometer to gradually press the pore water pressure gauge device into the soil through the CPT rod during burial. The burial depth can be accurately controlled as needed and can be recovered at any time. The whole device has a simple structure, convenient operation, high test accuracy, and is simpler and faster than the traditional drilling hole burial method during test operation, and does not generate mud;

[0018] (2) The pore water pressure gauge device uses the CPT rod connecting sleeve and the penetration protection pipe to cooperate with the CPT rod, and can expose the pore water pressure gauge when lifting the CPT rod to make it contact with the test formation;

[0019] (3) The penetration protection pipe of the pore water pressure gauge device can prevent the soil layer from rubbing the pore water pressure gauge during the static pressure process and avoid damage;

[0020] (4) Rubber sealing rings are respectively provided at both ends of the pore water pressure gauge of the pore water pressure gauge device at the connection parts with the static penetration rod connecting sleeve and the penetration protection pipe, eliminating the need for the original sealing filler to be buried after hole formation and meeting the sealing requirements of the test part;

[0021] (5) The dry sand of the pore water pressure gauge device can cover the surface of the pore water pressure gauge when being extruded, playing a role in water permeability, ensuring the test effect, eliminating the need for the original filter material to be buried after hole formation, and meeting the water permeability requirements of the test part;

[0022] (6) The upper connection support on the static penetration rod connecting sleeve and the lower connection support on the penetration protection pipe of the pore water pressure gauge device are designed to be conical, increasing the contact area between the pore water pressure gauge device and the formation, facilitating ensuring the stability of the pore water pressure gauge device during penetration. And when the static penetration rod is lifted, the lower connection support increases the resistance to keep the penetration protection pipe stationary, facilitating the pore water pressure gauge to be pulled out with the static penetration rod 2, so as to expose the penetration protection pipe for testing.

[0023] (7) Using the static penetration rod, the cable of the pore water pressure gauge is led out to the ground from the static penetration rod and connected to the receiving device, and the static penetration rod plays a role in protecting the cable.

[0024] In summary, the present invention avoids the mud generated during drilling and burying, is environmentally hygienic, has a simple device structure, is convenient to operate, has high test accuracy, saves time and effort, and is both economical and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0026] Figure 2 It is a schematic diagram of the structure of the pore water pressure gauge device in the present invention when the static penetration rod connecting sleeve and the penetration protection pipe are closed.

[0027] Figure 3 It is an assembly schematic diagram of the pore water pressure gauge in the present invention.

[0028] Figure 4 It is a schematic diagram of the structure of the pore water pressure gauge in the present invention when the pore water pressure gauge connecting pipe and the pore water pressure gauge body are separated.

[0029] Figure 5 It is a schematic diagram of the structure of the static penetration rod connecting sleeve in the present invention.

[0030] Figure 6 It is an assembly schematic diagram of the penetration protection pipe in the present invention.

[0031] Figure 7 It is a schematic diagram of the structure of the penetration protection pipe in the present invention when the upper penetration protection pipe and the lower penetration protection pipe are separated.

[0032] Figure 8 This is a cross-sectional view of the lower connecting support in the present invention.

[0033] Figure 9 This is a schematic structural view of the pore water pressure gauge device in the present invention when the static penetration sounding rod connecting sleeve is driven to be lifted.

[0034] The component numbers in the figure are as follows:

[0035] 1 Static cone penetrometer

[0036] 2 Static penetration sounding rod

[0037] 3 Pore water pressure gauge device

[0038] 4 Pore water pressure gauge connecting pipe

[0039] 5 Upper connector

[0040] 6 Upper rubber sealing ring

[0041] 7 Pore water pressure gauge body

[0042] 8 Lower connector

[0043] 9 Lower rubber sealing ring

[0044] 10 Cable

[0045] 11 Static penetration sounding rod connecting sleeve

[0046] 12 Upper connecting support

[0047] 13 Upper penetration protection pipe

[0048] 14 Lower connecting support

[0049] 15 Lower penetration protection pipe

[0050] 16 Penetration head

[0051] 17 Dry sand

[0052] 18 Protrusion. Detailed implementation manners

[0053] The following details the specific implementation manners of the present invention with reference to the accompanying drawings, so that those skilled in the art can more clearly understand how to practice the present invention. Although the present invention is described in conjunction with its preferred specific implementation manners, these implementation manners are only illustrative and do not limit the scope of the present invention.

[0054] See Figure 1 , a static pressure type pore water pressure testing device, including a static cone penetrometer 1, a static penetration sounding rod 2, and a pore water pressure gauge device 3. The static cone penetrometer 1 is installed with the static penetration sounding rod 2, and the lower end of the static penetration sounding rod 2 is installed with the pore water pressure gauge device 3.

[0055] See Figure 2 The pore water pressure gauge device 3 includes a pore water pressure gauge, a static penetration rod connecting sleeve 11, a penetration protection tube, and dry sand 17. The static penetration rod connecting sleeve 11 and the penetration protection tube are sleeved outside the pore water pressure gauge in an up-and-down arrangement, and the pore water pressure gauge, the static penetration rod connecting sleeve 11, and the penetration protection tube can move relatively axially.

[0056] See Figure 3 and Figure 4 The pore water pressure gauge includes a pore water pressure gauge connecting pipe 4 and a pore water pressure gauge body 7 connected up and down. The upper end of the pore water pressure gauge connecting pipe 4 is connected with an upper connector 5 and is sleeved with an upper rubber sealing ring 6. The lower end of the pore water pressure gauge connecting pipe 4 is threadedly connected to the upper end of the pore water pressure gauge body 7. The pore water pressure gauge body 7 is used for pore water pressure detection. A cable 10 is connected to the upper end of the pore water pressure gauge body 7, and the cable 10 is led upward from the pore water pressure gauge connecting pipe 4, the static penetration rod connecting sleeve 11, and the static penetration rod 2. The lower end of the pore water pressure gauge body 7 is connected with a lower connector 8 and is sleeved with a lower rubber sealing ring 9.

[0057] See Figure 5 The upper end of the static penetration rod connecting sleeve 11 is threadedly connected to the lower end of the static penetration rod 2, and an upper connecting support 12 is installed at the lower end of the static penetration rod connecting sleeve 11. The upper connecting support 12 is arranged below the upper connector 5 and the upper rubber sealing ring 6 and limits the axial downward movement of the upper connector 5 and the upper rubber sealing ring 6. The upper rubber sealing ring 6 is arranged between the upper connecting support 12 and the upper connector 5 and plays a role in water stop and sealing.

[0058] See Figure 6 and Figure 7 The penetration protection tube includes an upper penetration protection tube 13, a lower penetration protection tube 15, and a penetration head 16 connected in sequence from top to bottom. The upper end of the upper penetration protection tube 13 is installed with a lower connecting support 14. The lower end of the upper penetration protection tube 13 is threadedly connected to the upper end of the lower penetration protection tube 15. The lower connecting support 14 is arranged above the lower connector 8 and the lower rubber sealing ring 9 and limits the axial upward movement of the lower connector 8 and the lower rubber sealing ring 9. The lower rubber sealing ring 9 is arranged between the lower connecting support 14 and the lower connector 8 and plays a role in water stop and sealing. Among them, dry sand 17 is filled between the lower connecting support 14 and the lower rubber sealing ring 9 inside the penetration protection tube. The dry sand 17 is mainly used to cover the surface of the pore water pressure gauge body 7 and plays a role as a filter material; See Figure 8, a hole and groove structure for upward extrusion of dry sand 17 to the outside of the penetration protection tube is provided at the lower connecting support 14. Specifically, a plurality of circumferentially uniformly distributed protrusions 18 are provided on the inner wall of the lower connecting support 14. A plurality of axially extending holes are formed circumferentially uniformly by the inner wall of the lower connecting support 14, the plurality of protrusions 18, and the outer wall of the pore water pressure gauge. The holes are for upward extrusion of dry sand 17 to the outside of the penetration protection tube. The lower end of the lower penetration protection tube 15 is connected with a conical penetration head 16, and the penetration head 16 is used for opening a hole in the soil.

[0059] When assembling the pore water pressure gauge device 3, first disassemble the pore water pressure gauge, then disassemble the penetration protection tube, install the pore water pressure gauge body 7 into the upper penetration protection tube 13, and then connect the lower penetration protection tube 15 with the upper penetration protection tube 13. Next, install the pore water pressure gauge connecting pipe 4 into the static cone penetration rod connecting sleeve 11, then connect the pore water pressure gauge connecting pipe 4 and the pore water pressure gauge body 7, and then penetrate dry sand 17 into the penetration protection tube through the hole and groove structure. Finally, lead out the cable 10 of the pore water pressure gauge body 7 from the pore water pressure gauge connecting pipe 4, the static cone penetration rod connecting sleeve 11, and the static cone penetration rod 2.

[0060] The pore water pressure gauge device 3 has the following two states: Refer to Figure 1 , when the static cone penetration rod connecting sleeve 11 is closed with the penetration protection tube, the pore water pressure gauge is located in the static cone penetration rod connecting sleeve 11 and the penetration protection tube. The upper connecting head 5 at the upper end of the pore water pressure gauge connecting pipe 4 is axially arranged in the static cone penetration rod connecting sleeve 11, and the lower connecting head 8 at the lower end of the pore water pressure gauge body 7 is arranged in the lower penetration protection tube 15. Dry sand 17 is penetrated into the pipe wall gap between the pore water pressure gauge and the penetration protection tube. Refer to Figure 8 , when the static cone penetration rod connecting sleeve 11 is driven to be lifted, the upper connecting support 12 at the lower end of the static cone penetration rod connecting sleeve 11 drives the upper connecting head 5 to lift the pore water pressure gauge out of the penetration protection tube. At the same time, the dry sand 17 in the penetration protection tube is extruded upward from the hole and groove structure by the lower rubber seal ring 9.

[0061] Before starting the test, refer to Figure 1 , place the static cone penetrometer 1 on the test ground, connect the static cone penetration rod 2 with the static cone penetration rod connecting sleeve 11 of the pore water pressure gauge device 3, and lead out the cable 10 of the pore water pressure gauge body 7 from the static cone penetration rod 2.

[0062] When conducting a test, the static penetration rod 2 is gradually pressed into the test formation by the static penetrometer 1 until the required burial depth. During this process, the penetration protection tube can prevent the pore water pressure gauge from being damaged due to soil layer friction. Then, the static penetration rod 2 is slowly lifted by the static penetrometer 1. The connecting sleeve 11 of the static penetration rod and the upper connecting support 12 are lifted together with the static penetration rod 2. During the lifting process, the upper connecting support 12 drives the upper connecting head 5 to move upward, thereby pulling out the pore water pressure gauge from the penetration protection tube. By controlling the length of the lifted static penetration rod 2, the body 7 of the pore water pressure gauge is exposed, and the pore water pressure test can be carried out with the body 7 of the pore water pressure gauge in contact with the test formation. During this process, the dry sand 17 is extruded and covers the surface of the body 7 of the pore water pressure gauge, playing a role of filter material for water permeability and ensuring the test effect.

[0063] When the test is completed, the static penetration rod 2 and the pore water pressure gauge device 3 are lifted out together by the static penetrometer 1 to achieve the purpose of recovery.

[0064] Among them, both the upper connecting support 12 and the lower connecting support 14 are conical; the bottom surface of the upper connecting support 12 is flush with the lower end pipe orifice of the connecting sleeve 11 of the static penetration rod, and the outer diameter of the bottom surface of the upper connecting support 12 is larger than the outer diameter of the connecting sleeve 11 of the static penetration rod, and the inner diameter of the bottom surface of the upper connecting support 12 is smaller than the inner diameter of the connecting sleeve 11 of the static penetration rod; the bottom surface of the lower connecting support 14 is flush with the upper end pipe orifice of the upper penetration protection tube 13, and the outer diameter of the bottom surface of the lower connecting support 14 is larger than the outer diameter of the upper penetration protection tube 13, and the inner diameter of the bottom surface of the lower connecting support 14 is smaller than the inner diameter of the upper penetration protection tube 13. Such a design increases the contact area between the pore water pressure gauge device 3 and the formation, facilitating ensuring the stability of the pore water pressure gauge device 3 during penetration. And when the static penetration rod 2 is lifted, the lower connecting support 14 increases the resistance to keep the penetration protection tube stationary, facilitating the pore water pressure gauge to be pulled out with the static penetration rod 2, so as to expose the penetration protection tube for testing. The upper connecting support 12 is closely fitted with the upper rubber sealing ring 6 to play a role of water stop and sealing.

[0065] It should be noted that for the present invention that has been fully described, there can also be various transformation and modification implementation schemes, which are not limited to the specific embodiments of the above implementation manners. The above embodiments are only used as the description of the present invention, rather than the limitation of the present invention. In short, the protection scope of the present invention should include those transformations, substitutions, and modifications that are obvious to those of ordinary skill in the art.

Claims

1. A hydrostatic pore water pressure testing device, characterized in that, it includes a static cone penetrometer, a static cone penetration rod, and a pore water pressure gauge device. The static cone penetration rod is installed on the static cone penetrometer, and the lower end of the static cone penetration rod is connected to the pore water pressure gauge device; the pore water pressure gauge device includes a pore water pressure gauge, a static cone penetration rod connection sleeve, a penetration protection tube, and dry sand. The static cone penetration rod connection sleeve and the penetration protection tube are sleeved outside the pore water pressure gauge in an up-and-down arrangement, and the pore water pressure gauge, the static cone penetration rod connection sleeve, and the penetration protection tube can move axially relative to each other; the pore water pressure gauge includes a pore water pressure gauge connection pipe and a pore water pressure gauge body connected up and down. The upper end of the pore water pressure gauge connection pipe is provided with an upper connection head and an upper rubber sealing ring, and the lower end of the pore water pressure gauge body is provided with a lower connection head and a lower rubber sealing ring; the upper end of the static cone penetration rod connection sleeve is connected to the lower end of the static cone penetration rod. The lower end of the static cone penetration rod connection sleeve is provided with an upper connection support. The upper connection support is arranged below the upper connection head and the upper rubber sealing ring, and limits the axial downward movement of the upper connection head and the upper rubber sealing ring. The upper rubber sealing ring is arranged between the upper connection support and the upper connection head; the penetration protection tube includes an upper penetration protection tube, a lower penetration protection tube, and a penetration head connected in sequence from top to bottom. The upper end of the upper penetration protection tube is provided with a lower connection support. The lower connection support is arranged above the lower connection head and the lower rubber sealing ring, and limits the axial upward movement of the lower connection head and the lower rubber sealing ring. The lower rubber sealing ring is arranged between the lower connection support and the lower connection head. Among them, dry sand is filled between the lower connection support and the lower rubber sealing ring in the penetration protection tube, and a hole groove structure for the dry sand to be extruded upward outside the penetration protection tube is provided at the lower connection support; the upper end of the pore water pressure gauge body is connected with a cable, and the cable is led out from the pore water pressure gauge connection pipe, the static cone penetration rod connection sleeve, and the static cone penetration rod; the lower end of the pore water pressure gauge connection pipe and the upper end of the pore water pressure gauge body, the upper end of the static cone penetration rod connection sleeve and the lower end of the static cone penetration rod, and the lower end of the upper penetration protection tube and the upper end of the lower penetration protection tube are all connected by threads.

2. The hydrostatic pore water pressure testing device according to claim 1, characterized in that, both the upper connection support and the lower connection support are conical.

3. The hydrostatic pore water pressure testing device according to claim 2, characterized in that, the bottom surface of the upper connection support is flush with the lower end pipe orifice of the static cone penetration rod connection sleeve, and the outer diameter of the bottom surface of the upper connection support is larger than the outer diameter of the static cone penetration rod connection sleeve; the bottom surface of the lower connection support is flush with the upper end pipe orifice of the upper penetration protection tube, and the outer diameter of the bottom surface of the lower connection support is larger than the outer diameter of the upper penetration protection tube.

4. The hydrostatic pore water pressure testing device according to claim 1, characterized in that, the hole groove structure is: a plurality of protrusions are circumferentially and evenly arranged on the inner wall of the lower connection support. The inner wall of the lower connection support, the plurality of protrusions, and the outer wall of the pore water pressure gauge enclose a plurality of axially extending holes circumferentially and evenly arranged, and the holes are for the dry sand to be extruded upward outside the penetration protection tube.

5. The hydrostatic pore water pressure testing device according to claim 1, characterized in that, the penetration head is conical.

6. A pore water pressure testing method, characterized in that, using the hydrostatic pore water pressure testing device according to any one of claims 1 to 5, comprising the following steps: (1) Set the static cone penetrometer on the test ground, and gradually press the static cone penetration rod into the test formation through the static cone penetrometer until the required burial depth; (2) Slowly lift the static cone penetration rod through the static cone penetrometer, lift the pore water pressure gauge out of the penetration casing, and control the lifting length so that the body of the pore water pressure gauge is exposed to contact with the test formation for pore water pressure testing; (3) After the test, lift the static cone penetration rod and the pore water pressure gauge device together through the static cone penetrometer.

7. The pore water pressure testing method according to claim 6, characterized in that, in step (2), the connecting sleeve of the static cone penetration rod and the upper connecting support are lifted together with the static cone penetration rod, and the upper connecting support drives the upper connecting head to move upward during the lifting process, thereby lifting the pore water pressure gauge out of the penetration casing.

8. The pore water pressure testing method according to claim 6 or 7, characterized in that, in step (2), during the process of lifting the pore water pressure gauge out of the penetration casing, the dry sand in the penetration casing is extruded upward from the hole groove by the lower rubber seal and covers the surface of the body of the pore water pressure gauge.

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