Underwater drilling and coring detection method and underwater drilling and coring device

Abstract

The invention relates to an underwater drilling and coring detection method and an underwater drilling and coring device, and belongs to the technical field of underwater drilling and coring. The underwater drilling coring detection method comprises the steps of protecting pipe mounting, drilling machine positioning, casing pipe sinking, hole cleaning, pile top standard penetration test, coring, pile bottom supporting layer standard penetration test and core sample strength and deformation modulus detection. According to the underwater drilling coring detection method, a standard penetration test is carried out in the coring process, the standard penetration test and drilling coring can share one drilling hole, meanwhile, a drilling core sample is used for carrying out strength and deformation modulus tests, three tasks are completed through one-time drilling, the workload can be reduced, the construction period can be shortened, the detection efficiency can be improved, and the overall cost can be reduced; moreover, according to the method, through a pile top standard penetration test, a pile bottom bearing layer standard penetration test and detection of strength data and deformation modulus data of a core sample, comprehensive quality detection can be conducted on the pile to be detected, and the method is suitable for drilling and coring detection work of the underwater DCM pile.

Description

Technical Field

[0001] The invention belongs to the technical field of underwater drilling and coring, and in particular relates to an underwater drilling and coring detection method and an underwater drilling and coring device. Background Art

[0002] Underwater deep cement mixing piles (DCM piles) use cement to solidify soft soil layers such as clay and silty clay in situ to achieve the purpose of foundation treatment. They have the advantages of being fast, efficient and cost-controlled, and have become the preferred process for soft foundation treatment of immersed tube tunnels. The quality of DCM piles is the key to controlling differential settlement of immersed tube tunnels.

[0003] DCM pile quality inspection requires drilling and sampling of DCM piles to test the quality of core samples. Different from the mature terrestrial cement mixing pile inspection technology, underwater drilling and coring are greatly affected by water flow, especially in locations with turbulent water flow, and the coring direction of the drill rod is difficult to control.

[0004] In the prior art, Chinese invention patent application CN115979700A discloses a method for coring detection. This patent does not involve underwater operations, and all detection work is performed after coring, which increases the cost of coring detection.

[0005] Therefore, how to provide a drilling and coring method suitable for underwater DCM piles to perform quality inspection on DCM piles is a technical problem that urgently needs to be solved. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides an underwater drilling coring inspection method and an underwater drilling coring device, which can conduct a comprehensive quality inspection of the piles to be inspected through a standard penetration test on the pile top, a standard penetration test on the bearing layer at the pile bottom, and the strength data and deformation modulus data of the inspection core sample, and can be applicable to the drilling coring inspection of underwater DCM piles.

[0007] The present invention provides an underwater drilling coring detection method, comprising the following steps:

[0008] Install the protective pipe: Install the protective pipe vertically at the coring hole of the coring platform and extend it into the water body;

[0009] Drilling rig in place: Move the drilling rig to the coring platform, make the drill rod of the drilling rig located at the center of the coring hole, and level the drilling rig;

[0010] Sinking casing: The casing is placed inside the protective pipe for sinking. A drill bit is installed at the bottom of the casing. The casing is sunk to the top of the pile to be inspected. After the pile top elevation is determined, the casing is penetrated 20cm into the pile top. A drainage pipe is installed at the top of the casing.

[0011] Hole cleaning: A hole cleaning drill is installed at the bottom of the drill pipe and lowered through the casing to clean the hole;

[0012] Standard penetration test on pile top: remove the hole-cleaning drill and replace it with a standard penetrator to conduct a standard penetration test on the pile top to verify the pile top elevation;

[0013] Coring: Take out a small amount of core sample from the top of the pile, and select a sampler according to the cement strength of the core sample from the top of the pile; install the sampler at the bottom of the drill pipe, and connect the top of the drill pipe to the water pump. When coring, turn on the water pump, and after the water fills the inside of the casing, lower the sampler to start coring and continue coring to 1.0m below the bottom of the pile to be tested, and obtain the test core sample;

[0014] Standard penetration test of pile bottom bearing layer: remove the sampler and replace it with a standard penetrator, lower it to the bottom of the hole for a standard penetration test to determine the pile bottom position and the nature of the bearing layer;

[0015] Core sample strength and deformation modulus testing: Test the test core sample to obtain the strength data and deformation modulus data of the test core sample.

[0016] This technical solution can conduct comprehensive quality inspection on the piles to be inspected through standard penetration test on the pile top, standard penetration test on the bearing layer at the pile bottom, and strength data and deformation modulus data of the test core samples, and can be applied to the drilling and coring inspection of underwater DCM piles.

[0017] In some embodiments, the step of installing the protective pipe further includes evaluating the depth of the water body before installing the protective pipe, and the depth of the protective pipe inserted into the water is not less than one third of the depth of the water body.

[0018] This technical solution can stably install the protective pipe by reasonably setting the depth of the protective pipe entering the water, ensuring that the protective pipe can work stably in an environment with turbulent water flow.

[0019] In some of the embodiments, in the hole step, when the hole cleaning operation reaches the pile top elevation or does not reach the pile top elevation and it is found that the hole bottom strength is significantly increased, the drill rod stops drilling and continues to flush water until the return water at the hole mouth becomes significantly clear for 2 minutes and then stops flushing.

[0020] This technical solution can ensure the thorough removal of impurities in the hole and improve the accuracy and reliability of subsequent coring and testing.

[0021] In some embodiments, in the coring step, the method for selecting the sampler is as follows:

[0022] The cement strength of the pile top core sample is C 样 , unit is MPa; when C 样 >2.8, use single-action single-tube sampler; when 1.2≤C 样 ≤2.8, use a single-action double-tube sampler; when C 样 When <1.2, a three-layer core tube sampler is used.

[0023] This technical solution ensures the adaptability and effectiveness of the coring process by selecting different types of samplers according to the cement strength of the pile top core sample.

[0024] In some of the embodiments, in the coring step, the drill pipe rotation speed is 130-150 r / min and the drilling pressure is 0.8-1.0 MPa.

[0025] This technical solution optimizes the parameter setting of the coring operation by setting the drill pipe speed and drilling pressure of the drilling rig, thereby ensuring the stability and efficiency of the coring process.

[0026] In some of the embodiments, in the coring step, the sampler takes samples every one meter from the top of the pile to the bottom of the pile, and the obtained core sample is made into a first test core sample with a height-to-diameter ratio of 1:1; in the testing step, the first test core sample is subjected to an indoor unconfined compressive strength test to obtain strength data of the first test core sample.

[0027] In some of the embodiments, in the detection step, the obtained core samples are divided into three parts: upper, middle and lower parts according to the pile body position, and two groups of core samples are selected from each part to make second detection core samples, and the second detection core samples are subjected to a deformation modulus test.

[0028] This technical solution can ensure the comprehensiveness and representativeness of the test samples by preparing the second test core sample.

[0029] In some of the embodiments, a strain-controlled triaxial compression instrument is used to carry out a deformation modulus test on the second test core sample. In the deformation modulus test, the confining pressure of the triaxial compression instrument in the strain control room is set to 200 kPa, and axial stress is applied to the second test core sample at a loading rate of 0.12 mm / min to obtain a stress-strain curve; according to the stress-strain curve, the deformation modulus of the second test core sample is obtained by taking the stress value of 50% of the ultimate stress and the corresponding strain value.

[0030] Based on the above-mentioned underwater drilling coring detection method, the present invention further provides an underwater drilling coring device, which is applied to the above-mentioned underwater drilling coring detection method. The underwater drilling coring device comprises:

[0031] A coring platform, which is disposed on the hull deck and partially extends out of the deck;

[0032] A protective pipe is vertically installed at the coring hole of the coring platform and extends into the water body;

[0033] The casing is sleeved inside the protective pipe, the bottom of the casing is embedded in the top of the pile to be inspected, and a drainage pipe is installed on the top;

[0034] The drill rig, whose drill rod is located at the center of the core hole, is leveled and a sampler is installed at the bottom of the drill rod;

[0035] A water pump is provided, wherein the interior of the drill pipe is hollow, and the water outlet of the water pump is connected to the interior of the drill pipe.

[0036] The underwater drilling and coring device of this technical solution ensures the stability and efficiency of the underwater drilling and coring process through the coordinated action of the coring platform, protective pipe, casing, drilling rig and water pump, and effectively reduces the interference of water flow on the coring operation.

[0037] In some of the embodiments, a platform leg for support is provided at the bottom of the coring platform.

[0038] This technical solution enhances the stability of the coring platform by setting up platform legs.

[0039] Based on the above scheme, the underwater drilling coring detection method in the embodiment of the present invention performs a standard penetration test during the coring process, which can make the standard penetration test and the drilling coring share a borehole, and use the borehole core sample to perform strength and deformation modulus tests at the same time, completing three tasks in one drilling, which can reduce the workload of coring detection, shorten the detection period, improve detection efficiency, and reduce the overall detection cost; and, through the standard penetration test on the pile top, the standard penetration test on the bearing layer at the bottom of the pile, and the strength data and deformation modulus data of the detection core sample, the method can perform a comprehensive quality inspection on the pile to be inspected, and can be applicable to the drilling coring detection of underwater DCM piles. The underwater drilling coring device in the embodiment of the present invention ensures the stability and efficiency of the underwater drilling coring process through the coordinated action of the coring platform, protective pipe, casing, drilling rig and water pump, effectively reduces the interference of water flow on the coring operation, and improves the coring quality and the accuracy of the detection results. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0041] Figure 1 Flow chart of an underwater drilling coring detection method in an embodiment of the present invention;

[0042] Figure 2 It is a schematic structural diagram of an underwater coring device in an embodiment of the present invention.

[0043] In the figure:

[0044] 1. Coring platform; 101. Platform legs; 2. Protective pipe; 3. Casing; 4. Drilling rig; 401. Drill rod; 402. Sampler; 5. Water pump; 6. Piles to be inspected. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be understood that the terms "center", "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0047] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features.

[0048] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0049] In one embodiment of the underwater drilling coring detection method and underwater drilling coring device of the present invention, as Figure 1 As shown, the underwater drilling coring detection method comprises the following steps:

[0050] Installing the protective pipe: vertically install the protective pipe 2 at the coring hole of the coring platform 1 and extend it into the water body;

[0051] Drilling rig in place: the drilling rig 4 is moved to the coring platform 1, the drill rod 401 of the drilling rig 4 is located at the center of the coring hole, and the drilling rig 4 is leveled;

[0052] Casing: Casing 3 is placed inside protective tube 2 for sinking, a drill bit is installed at the bottom of casing 3, casing 3 is sunk to the top of pile 6 to be inspected, and after the pile top elevation is determined, it is penetrated 20cm into the pile top, and a drainage pipe is installed on the top of casing 3; in this step, casing 3 enters 20cm into the pile top to prevent the upper backfill sand from falling during coring and affecting the coring quality;

[0053] Hole cleaning: A hole cleaning drill is installed at the bottom of the drill rod 401 and lowered through the casing 3 to clean the hole;

[0054] Standard penetration test on pile top: remove the hole-cleaning drill and replace it with a standard penetrator to conduct a standard penetration test on the pile top to verify the pile top elevation;

[0055] Coring: Take out a small amount of the core sample from the top of the pile, and select the sampler 402 according to the cement strength of the core sample from the top of the pile; install the sampler 402 at the bottom of the drill rod 401, and connect the top of the drill rod 401 to the water pump 5; when coring, lower the sampler 402 to the top of the pile 6 to be inspected, then raise it by 10 cm, turn on the water pump 5, close the drain valve of the water pump 5, and only keep water in the drill rod 401. After the water fills the inside of the casing 3, lower the sampler 402 to start coring and continue coring to 1.0 m below the bottom of the pile 6 to obtain the test core sample;

[0056] Standard penetration test of pile bottom bearing layer: remove sampler 402 and replace it with a standard penetrator, lower it to the bottom of the hole to conduct a standard penetration test to determine the pile bottom position and the nature of the bearing layer;

[0057] Core sample strength and deformation modulus testing: Test the test core sample to obtain the strength data and deformation modulus data of the test core sample.

[0058] In the above-mentioned schematic embodiment, the underwater drilling coring inspection method in the embodiment of the present invention performs a standard penetration test during the coring process, which can enable the standard penetration test and the drilling coring to share a borehole, and at the same time use the borehole core sample to carry out strength and deformation modulus tests, completing three tasks in one drilling, which can reduce the workload of coring inspection, shorten the inspection period, improve the inspection efficiency, and reduce the overall inspection cost; and, the method can carry out a comprehensive quality inspection of the pile 6 to be inspected through the standard penetration test on the pile top, the standard penetration test on the bearing layer at the pile bottom, and the strength data and deformation modulus data of the inspection core sample, and can be applicable to the drilling coring inspection work of underwater DCM piles.

[0059] It should be noted that, in the drilling rig positioning step, after the drilling rig 4 is moved to the coring platform 1, the base of the drilling rig 4 is leveled; when the drill rod 401 of the drilling rig 4 is located at the center of the coring hole, the center of the vertical axis of the drilling rig 4, the center of the overhead sheave, the center of the protective pipe 2, and the center of the pile to be inspected 6 are on the same plumb line.

[0060] It should also be noted that in the coring step, after the coring operation begins, the drain valve of the water pump 5 is gradually opened to reduce the water pressure in the drill pipe 401 and ensure that there is a small amount of return water in the casing 3.

[0061] In some embodiments, the step of installing the protective pipe further includes evaluating the water depth before installing the protective pipe 2, and the water entry depth of the protective pipe 2 is not less than one third of the water depth.

[0062] In the above exemplary embodiment, by reasonably setting the water immersion depth of the protective tube 2, the protective tube 2 can be stably installed to ensure that the protective tube 2 can work stably in an environment with turbulent water flow, thereby improving the accuracy and reliability of the coring process.

[0063] In some embodiments, in the hole cleaning step, when the hole cleaning operation reaches the pile top elevation or does not reach the pile top elevation and the hole bottom strength is found to be significantly increased, the drill rod 401 stops drilling, and continues to flush water until the return water at the hole mouth becomes significantly clear for 2 minutes before stopping flushing. This embodiment can ensure the thorough removal of impurities in the hole and improve the accuracy and reliability of subsequent coring and detection.

[0064] In some embodiments, during the coring step, the sampler 402 is selected as follows:

[0065] The cement strength of the pile top core sample is C 样 , unit is MPa; when C 样 >2.8, use single-action single-tube sampler 402; when 1.2≤C 样 ≤2.8, use single-action double-tube sampler 402; when C 样 When <1.2, a three-layer core tube sampler 402 is used.

[0066] In the above exemplary embodiment, by selecting different types of samplers 402 according to the cement strength of the pile top core sample, the adaptability and effectiveness of the coring process are ensured, thereby improving the coring quality and the accuracy of the detection results.

[0067] It should be noted that the inner diameter of the sampler 402 is not less than 80 mm. The pile top core sample is sampled using a three-layer core tube sampler 402 .

[0068] In some embodiments, during the coring step, the rotation speed of the drill rod 401 is 130-150 r / min and the drilling pressure is 0.8-1.0 MPa. By setting the rotation speed and drilling pressure of the drill rod 401 of the drilling rig 4 and optimizing the parameter setting of the coring operation, the stability and efficiency of the coring process can be ensured, thereby improving the integrity of the core sample and the accuracy of the test results.

[0069] It should be noted that during the drilling process, the drilling speed is 50-100mm / min, and the drilling speed and drilling pressure are adjusted in time according to the drill core conditions and the impurity content and color of the return water. When it is found that the bottom hole pressure is significantly reduced or increased, the drilling pressure is adjusted in time or the drilling is stopped. During the drilling process, dry drilling without water for a long time is prohibited.

[0070] It should also be noted that the coring drilling is a round-trip drilling. After drilling to a predetermined depth, the water outlet of the water pump 5 is closed, the water valve is opened, and the drill is lifted, and a round of coring is completed. Each round of drilling does not exceed 1.0m. After each round of drilling, the sampler 402 is removed, the core sample is taken out, and the round drilling depth and the round core sample length are recorded; each round of drilling is performed to measure the depth of the drill rod 401 and the elevation of the hole.

[0071] In some embodiments, in the coring step, the sampler 402 takes samples every one meter from the top of the pile to the bottom of the pile, and makes the obtained core sample into a first test core sample with a height-to-diameter ratio of 1:1; in the testing step, the first test core sample is subjected to an indoor unconfined compressive strength test to obtain the strength data of the first test core sample.

[0072] Furthermore, a 100 kN press was used for the indoor unconfined compressive strength test. During the test, the profit control mode was adopted, and the pressure was applied at a rate of 0.15 kN / s until the pressure peak appeared. The test was terminated and the peak strength value was recorded.

[0073] In some embodiments, in the detection step, the core samples obtained are divided into three parts: upper, middle and lower parts according to the pile body position, and two groups of core samples are selected from each part to make the second detection core samples, and the deformation modulus test is performed on the second detection core samples. This embodiment can ensure the comprehensiveness and representativeness of the detection samples through the production of the second detection core samples, and improve the accuracy and reliability of the detection.

[0074] It should be noted that the second test core sample is produced according to a height-to-diameter ratio of 2:1; for example, a diameter of 10 cm and a height of 20 cm.

[0075] In some embodiments, a strain-controlled triaxial compression instrument is used to perform a deformation modulus test on the second test core sample. In the deformation modulus test, the confining pressure of the triaxial compression instrument in the strain control room is set to 200 kPa, and axial stress is applied to the second test core sample at a loading rate of 0.12 mm / min to obtain a stress-strain curve; according to the stress-strain curve, the deformation modulus of the second test core sample is calculated using the 50% stress value of the peak stress and its corresponding strain value.

[0076] It should be noted that the deformation parameter of the second test core sample is measured by the deformation modulus E50, which refers to the secant modulus of cement soil when the stress is 50% of the compressive strength. The ratio of stress to strain of half the peak stress of the second test core sample is taken, and the deformation modulus E50 of the second test core sample is obtained using formula (1). The expression of formula (1) is:

[0077]

[0078] In formula (1), σ 50 is the stress value corresponding to 50% of the peak stress of the second test core sample, ε50 It is the axial strain value when the peak stress of the second test core sample is 50%.

[0079] Based on the above underwater drilling coring detection method, such as Figure 2 As shown, the present invention also provides an underwater drilling coring device, which is applied to the above-mentioned underwater drilling coring detection method, and the underwater drilling coring device includes:

[0080] A coring platform 1, which is arranged on the hull deck and partially extends out of the deck;

[0081] A protective pipe 2 is vertically installed at the coring hole of the coring platform 1 and extends into the water body;

[0082] The casing 3 is sleeved inside the protective tube 2, the bottom of the casing 3 is embedded in the top of the pile 6 to be inspected, and a drainage pipe is installed on the top;

[0083] The drilling rig 4, whose drill rod 401 is located at the center of the core hole, is leveled, and a sampler 402 is installed at the bottom of the drill rod 401;

[0084] The water pump 5 and the drill rod 401 are hollow inside, and the water outlet of the water pump 5 is connected to the inside of the drill rod 401 .

[0085] In the above-mentioned schematic embodiment, the underwater drilling and coring device ensures the stability and efficiency of the underwater drilling and coring process through the coordinated action of the coring platform 1, the protective pipe 2, the casing 3, the drilling rig 4 and the water pump 5, effectively reduces the interference of the water flow on the coring operation, and improves the coring quality and the accuracy of the detection results.

[0086] In some embodiments, Figure 2 As shown, the bottom of the coring platform 1 is provided with a platform leg 101 for support. The arrangement of the platform leg 101 enhances the stability of the coring platform 1, reduces the influence of the water flow on the coring operation, and thus improves the accuracy and reliability of the coring process.

[0087] Furthermore, the platform legs 101 extend into the underwater strata to form an independent coring platform; or part of the platform legs 101 are fixed to the ship, and the coring platform 1 is partially cantilevered from the ship deck.

[0088] In some embodiments, the drainage pipe at the top of the casing 3 is connected to a wastewater collection tank to form a closed water circulation system.

[0089] Furthermore, the total length of the casing 3 is adjusted according to the fluctuation of the water surface, and the casing 3 is in the form of multiple sections of casing 3 connected to extend its total length.

[0090] Through the description of multiple embodiments of the underwater drilling coring detection method and underwater drilling coring device of the present invention, it can be seen that the underwater drilling coring detection method and underwater drilling coring device of the present invention have at least one or more of the following advantages:

[0091] 1. The underwater drilling coring detection method provided by the present invention performs a standard penetration test during the coring process, so that the standard penetration test and the drilling coring can share a borehole, and at the same time, the strength and deformation modulus tests are performed using the drilled core sample, so that three tasks can be completed in one drilling, which can reduce the workload of coring detection, shorten the detection period, improve the detection efficiency, and reduce the overall detection cost;

[0092] 2. The underwater coring inspection method provided by the present invention can conduct a comprehensive quality inspection of the pile 6 to be inspected through the standard penetration test of the pile top, the standard penetration test of the bearing layer at the pile bottom, and the strength data and deformation modulus data of the inspection core sample, and can be applicable to the drilling and coring inspection of underwater DCM piles;

[0093] 3. The underwater drilling and coring device provided by the present invention ensures the stability and efficiency of the underwater drilling and coring process through the coordinated action of the coring platform 1, the protective pipe 2, the casing 3, the drilling rig 4 and the water pump 5, effectively reduces the interference of the water flow on the coring operation, and improves the coring quality and the accuracy of the detection results.

[0094] Finally, it should be noted that: the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0095] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. An underwater drilling coring detection method, characterized in that: The following steps are involved: Install the protective pipe: Install the protective pipe vertically at the coring hole of the coring platform and extend it into the water body; Drilling rig in place: Move the drilling rig to the coring platform, make the drill rod of the drilling rig located at the center of the coring hole on the platform, and level the drilling rig; Sinking casing: The casing is placed inside the protective pipe for sinking. A drill bit is installed at the bottom of the casing. The casing is sunk to the top of the pile to be inspected. After the pile top elevation is determined, the casing is penetrated 20cm into the pile top. A drainage pipe is installed at the top of the casing. Hole cleaning: A hole cleaning drill is installed at the bottom of the drill pipe and lowered through the casing to clean the hole; Standard penetration test on pile top: remove the hole-cleaning drill and replace it with a standard penetrator to conduct a standard penetration test on the pile top to verify the pile top elevation; Coring: Take out a small amount of core sample from the top of the pile, and select a sampler according to the cement strength of the core sample from the top of the pile; install the sampler at the bottom of the drill pipe, and connect the top of the drill pipe to the water pump. When coring, turn on the water pump, and after the water fills the inside of the casing, lower the sampler to start coring and continue coring to 1.0m below the bottom of the pile to be tested, and obtain the test core sample; Standard penetration test of pile bottom bearing layer: remove the sampler and replace it with a standard penetrator, lower it to the bottom of the hole for standard penetration test, and determine the pile bottom position and bearing layer properties; Core sample strength and deformation modulus testing: Test the test core sample to obtain the strength data and deformation modulus data of the test core sample.

2. The underwater drilling coring detection method according to claim 1, characterized in that: The step of installing the protective pipe also includes evaluating the water depth before installing the protective pipe, and the water immersion depth of the protective pipe is not less than one third of the water depth.

3. The underwater drilling coring detection method according to claim 1, characterized in that: In the hole cleaning step, when the hole cleaning operation reaches the pile top elevation or does not reach the pile top elevation and it is found that the bottom strength of the hole is significantly increased, the drill rod stops drilling and continues to flush water until the return water at the hole mouth becomes obviously clear for 2 minutes and then stops flushing.

4. The underwater drilling coring detection method according to claim 1, characterized in that: In the coring step, the sampler selection method is as follows: The cement strength of the pile top core sample is C 样 , unit is MPa; when C 样 >2.8, use single-action single-tube sampler; when 1.2≤C 样 ≤2.8, use a single-action double-tube sampler; when C 样 When <1.2, a three-layer core tube sampler is used.

5. The underwater drilling coring detection method according to claim 1, characterized in that: In the coring step, when coring, the drill pipe speed is 130-150r / min and the drilling pressure is 0.8-1.0MPa.

6. The underwater drilling coring detection method according to claim 1 or 5, characterized in that: In the coring step, the sampler takes samples every one meter from the top of the pile to the bottom of the pile, and the obtained core sample is made into a first test core sample with a height-to-diameter ratio of 1:1; in the testing step, the first test core sample is subjected to an indoor unconfined compressive strength test to obtain the strength data of the first test core sample.

7. The underwater drilling coring detection method according to claim 6, characterized in that: In the testing step, the obtained core samples are divided into three parts: upper, middle and lower parts according to the position of the pile body. Two groups of core samples are selected from each part to make the second testing core samples, and the deformation modulus test is carried out on the second testing core samples.

8. The underwater drilling coring detection method according to claim 7, characterized in that: A strain-controlled triaxial compression instrument was used to conduct a deformation modulus test on the second test core sample. In the deformation modulus test, the confining pressure of the triaxial compression instrument in the strain control room was set to 200 kPa, and an axial stress was applied to the second test core sample at a loading rate of 0.12 mm / min to obtain a stress-strain curve. According to the stress-strain curve, the deformation modulus of the second test core sample is obtained by taking the stress value of 50% of the ultimate stress and the corresponding strain value.

9. An underwater coring device, characterized in that: The underwater coring detection method according to any one of claims 1 to 8, wherein the underwater coring device comprises: A coring platform, which is disposed on the hull deck and partially extends out of the deck; A protective pipe is vertically installed at the coring hole of the coring platform and extends into the water body; The casing is sleeved inside the protective pipe, the bottom of the casing is embedded in the top of the pile to be inspected, and a drainage pipe is installed on the top; The drilling rig, whose drill rod is located at the center of the core hole, is leveled and a sampler is installed at the bottom of the drill rod; A water pump is provided, wherein the interior of the drill pipe is hollow, and the water outlet of the water pump is connected to the interior of the drill pipe.

10. The underwater coring device according to claim 9, characterized in that: The bottom of the coring platform is provided with platform legs for support.

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