CN112362155A

CN112362155A - Dry hole elastic wave speed test probe and test method

Info

Publication number: CN112362155A
Application number: CN202011162460.6A
Authority: CN
Inventors: 熊燕; 冯少孔; 冯源; 张国新; 李松辉
Original assignee: Yuban Engineering Technology Shanghai Co ltd
Current assignee: Yuban Engineering Technology Shanghai Co ltd
Priority date: 2020-10-27
Filing date: 2020-10-27
Publication date: 2021-02-12

Abstract

The invention provides a probe and a method for testing the velocity of elastic waves in a dry hole, which comprises the following steps: the outer container is a flexible tubular structure with two open ends, two ends of the flexible tubular structure are respectively provided with a first front sealing head and a first rear sealing head, and a first sealing cavity is formed in the flexible tubular structure; the first sealed cavity is provided with a water injection channel and a water drainage channel; the inner container is arranged in the first sealed cavity, the inner container is of a flexible tubular structure with two open ends, a second front sealing head and a second rear sealing head are respectively arranged at two ends of the flexible tubular structure, and a second sealed cavity is formed in the flexible tubular structure; the second front sealing head and the rear sealing head are respectively fixed on the first front sealing head and the rear sealing head; the transducer is arranged in the second sealed cavity filled with insulating substances; injecting water into the first sealed cavity, and expanding the outer liner to make the outer wall of the outer liner closely contact with the wall of the hole, so that the elastic wave velocity test of the dry hole is converted into a water-containing well hole test; the invention utilizes the pressure wave sensor to test the elastic wave speed, and has high efficiency and good precision.

Description

Dry hole elastic wave speed test probe and test method

Technical Field

The invention relates to the technical field of geotechnical engineering detection, in particular to a probe and a test method for testing elastic wave velocity in a dry hole (waterless well hole).

Background

In recent years, energy infrastructure represented by hydropower stations and energy storage peak shaving power stations and water conservancy projects represented by large-scale water storage and water diversion are not only in China, but also extend abroad along with national strategies. First, in the electric power field, in order to actively develop hydropower resources in our country, a large hydropower station of world level such as sanxia hydropower station, lineate ferry hydropower station, and the like are successively built, and in addition, in order to reasonably utilize existing electric power resources, various pumped storage power stations are being vigorously developed in recent years. The construction of a hydropower station generally comprises the steps of excavating a water guide tunnel, an underground plant and constructing a dam; in the aspect of energy safety, China is building various underground petroleum and natural gas storage facilities and underground low-radioactive nuclear waste storage facilities; in the aspect of water conservancy construction, various long-distance water conveying and large-scale water storage facilities are actively constructed all over the country. All the large projects can not be constructed by geotechnical engineering, and in geotechnical engineering design and construction, the elastic wave velocity of geotechnical media is one of the most important physical parameters and is generally obtained by drilling and utilizing the in-hole elastic wave velocity test.

The in-hole elastic wave velocity test generally has 2 forms: when water exists in the well hole, the water is used as a transmission medium, and the pressure wave transducer is used for directly exciting and receiving elastic waves in the water, so that the method has high efficiency and good precision; when the borehole is empty of water, for example above the water level, or flat and inclined boreholes, because there is no elastic wave transmission medium in the borehole, it is common to use moving coil transducers which are mechanically pressed against the walls of the borehole and then excited at the surface to receive the elastic waves in the borehole. Because a mechanical device is needed to press the sensor on the hole wall, the efficiency is low, the data discreteness is large, and because the well hole is generally small, the reliability of the mechanical device is low, and the hole blocking accident that the probe is blocked in the well hole often occurs.

Through search, Chinese patent with application number CN200910068266.9 discloses a penetration type soil layer in-situ elastic wave testing device. The device comprises a connecting rod, an elastic wave damping block, two radiators, two shells, two piezoelectric ceramic ring vibrators, a conical penetration head, a probe connecting part and two signal wires. The penetration type soil layer in-situ elastic wave testing device provided by the patent can save the drilling step in the prior art, so that the testing cost can be greatly reduced. However, the above patents have the following disadvantages: firstly, the method is to additionally arrange a wave velocity testing device on a static sounding probe, belongs to the field of static sounding, is only suitable for softer strata such as cohesive soil, silty soil, sandy soil and the like, cannot be used for gravel strata, and cannot be used for wave velocity testing of rock strata; secondly, the applicable depth of static sounding in softer strata such as cohesive soil, silty soil, sandy soil and the like is generally several m to 10m, generally not more than 50m, and large-depth testing cannot be carried out; third, static sounding typically involves pressing the probe vertically downward into the ground, and cannot be pressed upward or laterally into the probe for testing.

Therefore, it is urgently needed to develop a testing device and a testing method capable of rapidly measuring the velocity of elastic waves in dry holes, especially in dry holes of rock masses.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a dry hole elastic wave speed test probe and a test method.

In order to solve the above problems, a first aspect of the present invention provides a dry borehole elastic wave velocity test probe, including: the outer container is of a first flexible tubular structure with two open ends, and a first front sealing head and a first rear sealing head are respectively arranged at two ends of the first flexible tubular structure, so that a first sealing cavity is formed inside the first flexible tubular structure; a water injection channel and a water drainage channel are arranged in the first sealed cavity, the water injection channel is used for injecting water into the first sealed cavity, and the water drainage channel is used for discharging water and air in the first sealed cavity;

the inner container is arranged in the first sealed cavity and is of a second flexible tubular structure with two open ends, and a second front sealing head and a second rear sealing head are respectively arranged at two ends of the second flexible tubular structure, so that a second sealed cavity is formed inside the second flexible tubular structure; the second front sealing head and the second rear sealing head are respectively fixed on the first front sealing head and the first rear sealing head, so that the inner container is fixed in a first sealing cavity of the outer container;

the transducer is arranged in the second sealed cavity, and an insulating substance is filled between the transducer and the second sealed cavity;

by injecting water into the first sealing cavity, the outer liner is expanded, the outer wall of the outer liner is in close contact with the wall of the well hole to be tested, and the probe is in a pressure water filling state, so that the dry hole elastic wave velocity test is converted into the water well hole elastic wave velocity test.

Preferably, the dry borehole elastic wave velocity test probe comprises:

the operating rod interface is arranged at the outer end of the first rear sealing head;

the operating rod is a rod-shaped component, one end of the operating rod is connected with the operating rod interface, and the other end of the operating rod is a free end and is used for being held by an operator.

Preferably, the second front sealing head and the second rear sealing head are respectively inserted into the first front sealing head and the first rear sealing head.

Preferably, the second rear sealing head is provided with a through hole for penetrating out of a signal line of the transducer, so that a signal lead of the transducer is led out of the second sealing cavity;

and the first rear sealing head is provided with a cable connector for connecting a signal lead of the transducer.

Preferably, the water filling channel includes:

the U-shaped water tank is arranged on the first front sealing head and is communicated with the first sealing cavity;

the water injection pipe is arranged in the first sealed cavity and positioned outside the second sealed cavity, one end of the water injection pipe is connected with the U-shaped water tank, and the other end of the water injection pipe penetrates out of the first sealed cavity and is used for being connected with a water pump; the water injection pipe and the U-shaped water tank form a J-shaped pipeline;

and the water injection valve is connected with the water injection pipe and is positioned outside the first seal cavity.

Preferably, the drain passage includes:

the drain hole is arranged on the first rear sealing head, and the inside of the first sealing cavity is communicated with the outside through the drain hole;

one end of the drain pipe is connected with the drain hole;

and the drain valve is connected with the drain pipe.

Preferably, the dry borehole elastic wave velocity test probe comprises: the large end part of the conical fairing is connected with the first front sealing head and covers the outer part of the first front sealing head.

Preferably, the number of the transducers is multiple, and the multiple transducers are distributed in a linear array along the length direction of the second sealed cavity.

Preferably, the insulating substance is a polyurethane gel;

preferably, the first flexible tubular structure and the second flexible tubular structure are polyurethane tubes;

preferably, the transducer is a pressure wave transducer.

The second aspect of the present invention provides a method for measuring the velocity of an elastic wave in a dry hole, which is performed by using the probe for measuring the velocity of an elastic wave in a dry hole, and includes:

injecting water into the first sealed cavity of the outer liner through the water injection channel, discharging air in the first sealed cavity through the water drainage channel, and completely filling the space between the inner liner and the outer liner with water;

when the water pressure in the first sealed cavity is higher than the external air pressure, the probe is enabled to be stiff but not expanded and thickened, water injection is stopped, and the probe is in a micro-pressure water filling state;

placing the probe into a position to be detected in a well hole, injecting water into the first sealed cavity through the water injection channel until the outer wall of the outer container is tightly contacted with the wall of the well hole after the outer container expands, wherein the state of the probe is called a pressure water filling state, and water injection is stopped; the pressure in the probe is kept unchanged, and the elastic wave speed test of the dry hole is converted into the elastic wave speed test of the water well hole.

Compared with the prior art, the invention has at least one of the following beneficial effects:

according to the probe, through the innovation of the integral structure, a water environment is formed by the inner container and the outer container of the flexible tubular structure, the dry hole elastic wave speed test is converted into the water well hole elastic wave speed test, the elastic wave speed test is carried out by using the pressure wave sensor, the efficiency is high, and the precision is good; the outer container can deform along with the shape of the well hole under the action of water pressure, can be used for straight well holes and inclined well holes, can also be used for bent holes and non-circular well holes, and has wide application range.

The probe has small diameter, the outer liner is expanded to be tightly coupled with the hole wall under the action of water pressure, and the outer liner recovers the original diameter immediately after water in the outer liner is discharged, so that the phenomenon that the probe is blocked in the hole and cannot be taken out is avoided.

According to the probe, the operating rod is arranged, the probe can be accurately placed in the test position by the operating rod, the operation is simple and visual, the cable does not need to be lifted, and the cable is not damaged, so that a thinner cable can be used.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic structural diagram of a dry hole elastic wave velocity test probe according to a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram illustrating an outer bladder micro-pressure water-filling state of a dry hole elastic wave velocity test probe according to a preferred embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating an outer bladder pressure water-filling state of the dry hole elastic wave velocity test probe according to a preferred embodiment of the present invention;

FIG. 4 is a schematic diagram of a dry hole elastic wave velocity test probe according to an embodiment of the present invention;

FIG. 5 is a waveform data example of a reception pattern within a ground excitation hole according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of a test procedure for excitation-reception in a well according to another embodiment of the present invention;

FIG. 7 is a waveform data example of an intra-hole transmit-receive mode in accordance with another embodiment of the present invention;

the scores in the figure are indicated as: the device comprises an outer liner 1, an inner liner 2, a transducer 3, an operation rod interface 4, an operation rod 5, a cable 6, a conical fairing 7, a data acquisition terminal 8, a stratum 9, a well 10, a hammer 11, a first sealing cavity 101, a first front sealing head 102, a first rear sealing head 103, a water injection pipe 104, a water injection valve 105, a water injection hole 106, a water discharge hole 107, a water discharge pipe 108, a water discharge valve 109, a first groove 110, a second groove 111, a U-shaped water tank 112, a second sealing cavity 201, a second front sealing head 202, a second rear sealing head 203, a first connecting piece 204, a second connecting piece 205 and a cable joint 206.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

Referring to fig. 1, a schematic structural diagram of a dry hole elastic wave velocity test probe according to a preferred embodiment of the present invention is shown, where the schematic structural diagram includes: an outer container 1, an inner container 2 and an energy converter 3; wherein, the inner container 2 is arranged inside the outer container 1, and the energy converter 3 is arranged inside the inner container 2. During testing, a probe is extended into a position to be tested of a well hole 10, a water environment is formed by the outer container 1 and the inner container 2, and elastic wave speed testing is carried out in a dry hole (a water-free hole) by using the pressure wave sensor.

The outer container 1 is a first flexible tubular structure with two open ends, and the first flexible tubular structure has elasticity and can expand under the action of water pressure; preferably, the first flexible tubular structure may be a polyurethane tube. A first front sealing head 102 and a first rear sealing head 103 are respectively arranged at the front end and the rear end of the first flexible tubular structure, so that a first sealing cavity 101 is formed inside the first flexible tubular structure; a water injection channel and a water drainage channel are arranged in the first sealed cavity 101, and the water injection channel is used for injecting water into the first sealed cavity 101. The drainage channel is used for draining water and air in the first sealed cavity 101, and the air is in the first sealed cavity 101 before water is injected. When water is injected into the first sealed cavity 101 in specific implementation, air in the first sealed cavity 101 is discharged through the water discharge channel, and after the air is discharged, water is discharged. The front and rear of the front and rear ends of the first flexible tubular structure are relative to the position of insertion into the borehole 10 to be measured, and the rear end of the first flexible tubular structure is near the inlet end of the borehole 10 to be measured.

The inner container 2 is arranged in the first sealed cavity 101, the inner container 2 is a second flexible tubular structure with two open ends, and two ends of the second flexible tubular structure are respectively provided with a second front sealing head 202 and a second rear sealing head 203, so that the interior of the second flexible tubular structure forms a second sealed cavity 201; the second front sealing head 202 and the second rear sealing head 203 are respectively fixed on the first front sealing head 102 and the first rear sealing head 103, so that the inner container 2 is fixed in the first sealed cavity 101 of the outer container 1. Preferably, the second flexible tubular structure may be a polyurethane tube. The transducer 3 is disposed in the second sealed cavity 201, and an insulating material is filled between the transducer 3 and the second sealed cavity 201. In a preferred embodiment, the insulating material is a material having an elastic wave velocity close to that of water, such as polyurethane gel or kerosene, and serves to transmit elastic waves. Since electronic components such as sensors are immersed in the insulating material, the insulating material is required.

As a preferred mode, the transducer 3 is a pressure wave transducer 3; the pressure wave transducer 3 includes both the transducer 3 that converts pressure waves into an electrical signal (i.e., the transducer 3 is used as a sensor) and the transducer 3 that converts an electrical signal into pressure waves (i.e., the transducer 3 is used as a seismic source). In specific implementation, the input end of the transducer 3 used as a seismic source is connected with the excitation drive circuit, and the output end of the transducer 3 used as a sensor is connected with an external data acquisition terminal 8; and the data acquisition is used for processing the received data to obtain the elastic wave velocity of the medium.

By injecting water into the first sealed cavity 101, the outer liner 1 is expanded, the outer wall of the outer liner 1 is in close contact with the wall of the well bore to be tested, and the probe is in a pressure water filling state, so that the dry-hole elastic wave velocity test is converted into the water-well-bore elastic wave velocity test. The probe can create a water environment in the dry hole through the inner container and the outer container, and the pressure wave transducer 3 is used for realizing high-efficiency and high-precision elastic wave speed measurement. The probe is simple in structure and convenient to operate, and is suitable for testing in various drill holes including vertical upward drill holes.

In other preferred embodiments, referring to fig. 1, the dry hole elastic wave velocity test probe comprises a lever interface 4 and a lever 5, wherein the lever interface 4 is disposed at an outer end of the first rear sealing head 103. The operating rod 5 is a rod-shaped component, one end of the operating rod 5 is connected with the operating rod interface 4, and the other end of the operating rod 5 is a free end and is used for being held by an operator. Utilize action bars 5 can accurately put into test position with the probe, easy operation is directly perceived, need not promote with cable 6, does not harm cable 6, consequently, can use thinner cable 6.

In other preferred embodiments, the second front sealing head 202 and the second rear sealing head 203 are respectively fixed to the first front sealing head 102 and the first rear sealing head 103 in an inserting manner. As a preferable mode, referring to fig. 1, outward extending protrusions are provided at the outer ends of the second front sealing head 202 and the second rear sealing head 203 (located outside the second sealing cavity 201), that is, the outer ends of the second front sealing head 202 and the second rear sealing head 203 are respectively formed for inserting the first connecting element 204 and the second connecting element 205. The inner ends (located inside the first sealed cavity 101) of the first front sealed head 102 and the first rear sealed head 103 are respectively provided with a first groove 110 and a second groove 111 for receiving and inserting a first connecting piece 204 and a second connecting piece 205, the sizes of the first groove 110 and the second groove 111 are matched with those of the first connecting piece 204 and the second connecting piece 205, the first connecting piece 204 is inserted into the first groove 110, and the second connecting piece 205 is inserted into the second groove 111, so that the two ends of the inner cavity are fixed with the two ends of the outer cavity. Of course, the second front sealing head 202 and the first front sealing head 102, and the second rear sealing head 203 and the first rear sealing head 103 may be fixed by other connection methods besides the plug connection method.

In other preferred embodiments, referring to fig. 1, the second rear sealing head 203 is provided with a through hole for passing through the signal line of the transducer 3, so that the signal lead of the transducer 3 is led out of the second sealing cavity 201.

The first rear sealing head 103 is provided with cable connections 206 for connecting the signal leads of the transducer 3.

In some other preferred embodiments, the number of the transducers may be one or more, and when a plurality of transducers are used for measurement, the plurality of transducers are distributed in a linear array along the length of the second sealed cavity.

In other preferred embodiments, referring to fig. 1, the water injection passage includes a U-shaped water tank 112 (or U-shaped water pipe), a water injection pipe 104, and a water injection valve 105; the U-shaped water tank 112 is disposed on the first front sealing head 102, and the U-shaped water tank 112 is communicated with the first sealing chamber 101. One end of the U-shaped water tank 112 is connected to the water injection pipe 104, and the other end is provided with a water injection hole 106, and water is injected into the first sealed cavity 101 from the water injection hole 106.

The water injection pipe 104 is arranged in the first sealed cavity 101 and is positioned outside the second sealed cavity 201, one end of the water injection pipe 104 is connected with the U-shaped water tank 112, and the other end of the water injection pipe 104 penetrates out of the first sealed cavity 101 and can be used for connecting a water pump; the water injection pipe 104 and the U-shaped water tank form a J-shaped pipeline.

The water injection valve 105 is connected to the water injection pipe 104 and is located outside the first hermetically sealed chamber 101. The water inlet of the water injection valve 105 is externally connected with a water pump. The water inlet switch in the water filling channel is controlled by a water filling valve 105.

In some other preferred embodiments, the drain channel includes: a drain hole 107, a drain pipe 108 and a drain valve 109, wherein the drain hole 107 is arranged on the first rear sealing head 103, and the inside of the first sealing cavity is communicated with the outside through the drain hole 107; one end of the drain pipe 108 is connected with the drain hole 107; the drain valve 109 is connected to the drain pipe 108.

In other preferred embodiments, the dry hole elastic wave velocity test probe comprises a conical fairing 7, and the large end of the conical fairing 7 is connected with the first front sealing head 102 and covers the outside of the first front sealing head 102. The fairing with the conical structure can reduce the penetration resistance, so that the probe can be more easily placed in the drill hole.

Based on the elastic wave velocity test probe in the dry hole, in another embodiment, a method for testing the elastic wave velocity in the dry hole is provided, which is performed by using the elastic wave velocity test probe in the dry hole, and includes the following steps:

before testing:

referring to fig. 1, a water filling valve 105 is first connected to a water pump, and a drain valve 109 is connected to a waste water tank.

Then, the water filling valve 105 and the water discharge valve 109 are opened, the water pump is started to fill water into the outer liner 1, and the air in the outer liner 1 is discharged from the water discharge hole 107 through the water discharge valve 109.

When the space between the inner container 2 and the outer container 1 is completely filled with water and a small amount of water flows into the waste water bucket through the drain valve 109, the drain valve 109 is turned off.

When the internal water pressure of the outer liner 1 is slightly higher than the external air pressure and the probe is deformed but does not expand to be thick, the water pump and the water injection valve 105 are closed, and the state of the probe is called a micro-pressure water filling state, which is shown in figure 2, which is a schematic diagram of the micro-pressure water filling state of the outer liner 1 and shows that the outer liner 1 is filled with water, the probe is deformed to be thick, but the water pressure is not enough to expand and thicken the outer wall of the outer liner 1; at this point, the preparation is complete. The purpose of filling the probe to a slight pressure prior to placing the probe in the wellbore 10 is to make the probe stiff and easier to place in the bore.

During testing:

firstly, an operating rod 5 is connected with an operating rod interface on a first rear sealing head 103 of the outer container 1;

connecting the probe with data acquisition equipment by using a cable 6;

connecting a water injection valve 105 with a water pump;

the probe is placed in the desired position in the borehole 10 by means of the operating rod 5.

The water injection valve 105 is opened, the water pump is started to inject water between the inner container and the outer container 1 of the probe until the outer container 1 expands and the outer wall of the outer container 1 is in close contact with the hole wall, at the moment, the state of the probe is called a pressure water filling state, referring to fig. 3, a schematic diagram of the pressure water filling state of the outer container 1 is shown, the diagram shows that the outer container 1 is filled with water, the outer wall of the outer container 1 expands and becomes thick under the action of water pressure, and if the probe is placed in the well hole 10, the outer wall of the outer container 1 is in close coupling with the hole wall.

The water injection valve and the water pump are closed to keep the pressure in the probe unchanged, and then the elastic wave speed test can be carried out as in the case of the well hole 10 with water.

After the test is completed, the drain valve 109 is opened, water flows into the waste water barrel, the outer container 1 is contracted to the original size, and then the probe is taken out by the operating rod.

If the borehole 10 is deep and cannot be tested at one time, the operation rod can be put into the required depth, and the process is repeated to complete the test at all depths.

Referring to fig. 4, a first application example of the dry-hole elastic wave velocity test probe is provided based on the structural features of the dry-hole elastic wave velocity test probe, all transducers in the application example adopt the transducer 3 for converting pressure wave signals into electrical signals, namely, a sensor, and an output end of the sensor is connected with an external data acquisition terminal 8. The sensor may be a hydrophone.

The transducer 3 in the probe is composed of 12 sensors which are arranged linearly at equal intervals to form a linear sensor array, wherein the distance between the sensors is 0.2 m. During testing, firstly, filling water into the probe to a micro-pressure water filling state; secondly, the probe is placed in the position to be tested in the well hole 10 by using an operating rod, so that the sensor at the most front end is aligned to the maximum depth of the testing section; filling water into the probe to a pressure water filling state, and closely coupling the outer wall of the probe outer container 1 with the hole wall; impacting the ground at the position of the wellhead by using the hammer head 11, enabling elastic waves generated by impact to pass through the stratum 9 to sequentially reach each sensor in the well hole 10 and be sensed by the sensors, and simultaneously outputting a signal (trigger signal) to the data acquisition terminal 8 by a force sensor on the impact hammer head 11; after receiving the trigger signal, the data acquisition terminal 8 starts to acquire and record the vibration signal sensed by the sensor in the well 10; sixthly, if the sensor array of the probe cannot cover the whole testing well section, the drainage valve is opened to drain the outer container 1, then the probe is moved to a new position through the operating rod, the steps from step three to step five are repeated until the whole testing well section is tested, then the drainage valve is opened to drain the outer container 1 to a non-pressure state, then the probe is taken out, and the test is finished.

Referring to fig. 5, since the linear sensor array is used, and the waveform data received by each sensor is arranged according to the sensor depth, it can be seen that the arrival time of the elastic wave increases from shallow to deep. The elastic wave velocity of the formation 9 in the borehole 10 between the ith sensor and the (i + 1) th sensor may be calculated by:

Vi＝δDi/δTi

δ Di ═ (depth of i +1 th sensor-depth of i th sensor)

δ Ti ═ (time of arrival of elastic wave at the i +1 th sensor — time of arrival of elastic wave at the i th sensor).

Referring to fig. 6, another application example of the dry hole elastic wave velocity test probe is provided based on the structural features of the dry hole elastic wave velocity test probe, in which the first transducer is a transducer (seismic source) for converting an electrical signal into mechanical vibration, and the remaining transducers are transducers, i.e., sensors, for converting a pressure wave signal into an electrical signal.

The transducer of the probe is composed of 12 transducers to form a transducer array, wherein the first transducer is a transducer (namely used as a seismic source) for converting a voltage signal into a mechanical vibration signal and is used as a transmitting signal source, and the input end of the first transducer is connected with an excitation driving circuit; and the first transducer is linearly arranged with the remaining 11 transducers at equal intervals. The remaining 11 transducers are sensors (the remaining 11 transducers convert the vibration signals into electric signals, namely, the electric signals are used as the sensors), and the output ends of the 11 sensors are connected with an external data acquisition terminal 8; and the data acquisition is used for processing the received data to obtain the elastic wave velocity of the medium. The distance between the signal source and the first sensor is 0.2m, and the distance between the sensors is also 0.2 m. During testing, firstly, filling water into the probe to a micro-pressure water filling state; secondly, the probe is placed in the position to be tested in the well hole 10 by using the operating rod, and the transducer at the most front end is aligned to the maximum depth of the testing section; filling water into the probe to a pressure water filling state, and closely coupling the outer wall of the probe outer container 1 with the hole wall; the data acquisition terminal 8 sends an excitation command to the signal source, the signal source transmits elastic waves, the elastic waves penetrate through the water in the outer container 1 and the outer wall of the outer container 1 and are refracted along the hole wall, the refracted waves penetrate through the outer wall of the outer container 1 and the water in the outer container 1 again and sequentially reach each sensor in the well hole 10 and are sensed by the sensors, and the data acquisition terminal 8 starts to acquire and record vibration signals sensed by the sensors in the well hole 10 while sending the excitation command; sixthly, if the sensor array of the probe cannot cover the whole testing well section, opening the water discharge valve to discharge water to the outer container 1, then moving the probe to a new position through the operating rod, repeating the steps from step three to step five until the whole testing well section is tested, then, opening the water discharge valve to discharge water to the outer container 1 until the pressure is not applied, then taking out the probe, and finishing the test.

Referring to fig. 7, since a plurality of sensors are arranged in a linear array, and the waveform data received by each sensor is arranged according to the depth of the sensor, it can be seen that the arrival time of the elastic wave increases from shallow to deep. The elastic wave velocity of the formation 9 in the borehole 10 between the ith sensor and the (i + 1) th sensor may be calculated by:

Vi＝δDi/δTi

δ Di ═ (depth of the i +1 st sensor-depth of the i th sensor)

The probe and the method for testing the velocity of the dry hole elastic wave can be used for testing the velocity of the elastic wave of the dry hole with low underground water level, rock crack development and incapability of maintaining the water level in the dry hole, can also be used for testing the velocity of the wave of a flat hole, an inclined hole inclined upwards and a vertical hole upwards in ceilings of tunnels, underground plants and the like, have the advantages of good interference resistance, high testing efficiency, convenience in operation, safety and reliability, and can provide powerful testing tools and testing methods for geotechnical engineering of the tunnels, the underground plants and the like.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. A dry borehole elastic wave velocity test probe, comprising:

the outer container is of a first flexible tubular structure with two open ends, and a first front sealing head and a first rear sealing head are respectively arranged at two ends of the first flexible tubular structure, so that a first sealing cavity is formed inside the first flexible tubular structure; a water injection channel and a water drainage channel are arranged in the first sealed cavity, the water injection channel is used for injecting water into the first sealed cavity, and the water drainage channel is used for discharging water and air in the first sealed cavity;

2. The dry borehole elastic wave velocity test probe according to claim 1, further comprising:

3. The dry hole elastic wave velocity test probe according to claim 1, wherein the second front sealing head and the second rear sealing head are respectively plugged with the first front sealing head and the first rear sealing head.

4. The dry borehole elastic wave velocity test probe according to claim 1,

the second rear sealing head is provided with a through hole for penetrating out of a signal wire of the transducer, so that a signal lead of the transducer is led out of the second sealing cavity;

5. The dry borehole elastic wave velocity test probe according to claim 1, wherein the water injection channel comprises:

6. The dry borehole elastic wave velocity test probe according to claim 1, wherein the drainage channel comprises:

one end of the drain pipe is connected with the drain hole;

and the drain valve is connected with the drain pipe.

7. The dry borehole elastic wave velocity test probe according to any one of claims 1 to 6, further comprising: the large end part of the conical fairing is connected with the first front sealing head and covers the outer part of the first front sealing head.

8. The dry borehole elastic wave velocity test probe according to any one of claims 1 to 6, wherein the number of the transducers is plural, and the plural transducers are distributed in a linear array along a length direction of the second sealed cavity.

9. The dry borehole elastic wave velocity test probe according to any one of claims 1 to 6, characterized by one or more of the following features:

the insulating substance is polyurethane gel or kerosene;

the first flexible tubular structure and the second flexible tubular structure are polyurethane tubes;

the transducer is a pressure wave transducer.

10. A method for measuring the velocity of an elastic wave in a dry hole, which is performed by using the probe for measuring the velocity of an elastic wave in a dry hole according to any one of claims 1 to 9, comprising: