Self-excited seismic wave static sounding testing device

Abstract

The invention relates to the field of geological exploration, in particular to a self-excited seismic wave static sounding testing device. Comprising a seismic wave self-excitation probe rod, a pore pressure static sounding conical probe and ground test analysis equipment, a seismic wave exciter is arranged in the seismic wave self-excitation probe rod; the upper part and the lower part of the pore pressure static sounding conical probe are respectively provided with a group of three-way detectors; and the three-way detector and the seismic wave exciter are electrically connected with the ground test analysis equipment. According to the invention, seismic wave self-excitation can be carried out, and seismic wave data can be tested while drilling in real time. Meanwhile, other sensors are combined, the small strain shear deformation characteristic and the soil dynamic property of the soil body are comprehensively evaluated, and more accurate, efficient and comprehensive data reference and performance evaluation basis are provided for geotechnical engineering investigation and soil body characteristic research.

Description

Technical Field

[0001] The present invention relates to the field of geological exploration, and particularly to a self-excited seismic wave static cone penetration test device. Background Art

[0002] The piezocone penetration test (CPTU) technology, as a new type of static cone penetration technology, has been widely used in various current engineering projects. This technology is developed on the basis of the traditional CPT static cone penetration technology. The traditional CPT technology is to press the sounding rod equipped with a cone tip into the test soil layer by means of a pressure device, and then use a measurement system to measure geotechnical engineering parameters such as the cone tip resistance and the sidewall friction resistance of the soil, so as to determine some basic physical and mechanical properties of the soil. The piezocone penetration test technology fully considers the special engineering properties of the soil, adds a pore water pressure sensor in the static cone penetration probe, and can measure the pore water pressure in real time. This technology has significant advantages such as high accuracy of test parameters, large amount of data acquisition, in-situ testability, convenient operation, small disturbance to the soil and low cost. In the field of international engineering investigation, the static cone penetration technology has partially or completely replaced drilling and sampling operations.

[0003] The seismic wave static cone penetration technology can effectively measure the in-situ shear wave velocity and dynamic shear modulus of soil layers, and has characteristics such as fast speed, economy and in-situ measurement. When the probe penetrates to a specific depth, a shear wave is excited by manually hitting an iron plate with a hammer. At the same time, the built-in circuit of the probe starts to collect and store the seismic wave waveform data. After the storage is completed, the data will be automatically transmitted to the surface computer through the serial port, and then the computer software will process the collected data and display the waveform. However, the measurement of the shear wave velocity is affected by the propagation direction and excitation intensity of the shear wave, and both of these factors are affected by the manual hammer excitation operation. In the current seismic wave static cone penetration test, the transient excitation method is usually adopted, such as blasting, hammering, etc., which generates shear waves with uncontrollable frequency, phase and amplitude, and estimates the shear wave velocity of the rock and soil layer by calculating the time difference between the initial motion moment of the measuring point and the moment when the shear wave is emitted. These methods have the following defects: 1) It is difficult to determine the propagation direction of the excited shear wave because the position of the hammering point or blasting point is uncertain due to human factors, which affects the propagation direction of the shear wave; 2) The excitation intensity of the shear wave is not fixed because the hammering energy or blasting energy varies due to human factors, resulting in uncertain excitation intensity, which affects the propagation depth of the shear wave; 3) The excitation methods such as hammering and blasting are cumbersome and time-consuming, which is not conducive to improving the experimental efficiency, and there are certain safety risks. Generally speaking, the seismic wave excitation method in the current seismic wave static cone penetration test has deficiencies such as difficult quality control, low measurement accuracy, poor repeatability and cumbersome and time-consuming operation. Summary of the Invention

[0004] Objective of the Invention: In view of the many deficiencies in the seismic wave excitation method used in the seismic wave static cone penetration test in the prior art, such as great difficulty in quality control, low measurement accuracy, poor repeatability, and cumbersome and time-consuming operation, a self-excited seismic wave piezocone penetration device is proposed. This device can achieve self-excitation of seismic waves and real-time test seismic wave data during the drilling process, so as to accurately and effectively identify the seismic resistance level, fracture development status, and other special soil engineering properties of the formation.

[0005] Technical Solution: A self-excited seismic wave static cone penetration test device includes a seismic wave self-excitation drill rod, a piezocone penetration conical probe, and ground test and analysis equipment;

[0006] Among them, the seismic wave self-excitation drill rod and the piezocone penetration conical probe are sequentially connected up and down;

[0007] Inside the seismic wave self-excitation drill rod, a seismic wave exciter is provided;

[0008] The piezocone penetration conical probe includes a friction sleeve and a cone tip probe that are sequentially connected up and down;

[0009] A set of three-component geophones are respectively provided at the upper and lower parts of the friction sleeve;

[0010] The three-component geophones, the seismic wave exciter are electrically connected to the ground test and analysis equipment.

[0011] Preferably, the material of the seismic wave self-excitation drill rod is wave-absorbing material; the three-component geophones are wrapped and isolated by a wave-absorbing material sleeve.

[0012] Preferably, the piezocone penetration conical probe is internally integrated with a pore water pressure sensor, a skin friction sensor, and a cone tip pressure sensor;

[0013] The pore water pressure sensor, the skin friction sensor, and the cone tip pressure sensor are electrically connected to the ground test and analysis equipment.

[0014] Preferably, a pore pressure filter ring is also arranged between the friction sleeve and the cone tip probe.

[0015] Preferably, the detection process of the seismic wave static cone penetration test device is as follows:

[0016] The connected seismic wave self-excitation drill rod and the piezocone penetration conical probe are in-situ penetrated through a static cone penetration equipment at a penetration speed of v;

[0017] After the seismic wave static cone penetration test device is inserted into the soil, the ground test and analysis equipment controls the seismic wave exciter to intermittently send out impact signals;

[0018] After each impact signal is emitted, the ground test and analysis equipment calculates the soil layer parameters based on the signals received from two sets of three-component geophones.

[0019] Preferably, the soil layer parameters include the dynamic shear modulus of the soil mass ;

[0020] Specifically, the calculation steps of

[0021] Calculate the time difference of signal propagation:

[0022]

[0023] where, △t is the time difference of signal propagation;

[0024] t1 is the time when the lower three-component geophone receives the signal after this impact signal is emitted;

[0025] t2 is the time when the upper three-component geophone receives the signal after this impact signal is emitted;

[0026] Calculate the signal propagation distance:

[0027]

[0028]

[0029] where, D is the signal propagation distance;

[0030] L is the spacing between two sets of three-component geophones;

[0031] S is the penetration distance of the probe rod within the time of Δt;

[0032] Calculate the shear wave velocity:

[0033]

[0034] where, V S is the shear wave velocity;

[0035] Calculate the dynamic shear modulus of the soil mass:

[0036]

[0037] where, represents the natural density of the soil layer.

[0038] Preferably, the soil layer parameters include the surface wave velocity of the soil layer ;

[0039] Specifically, the calculation method of

[0040]

[0041] Among them, μ represents the Poisson's ratio of the soil mass.

[0042] Beneficial effects:

[0043] Based on in-depth exploration and a large number of experimental analyses of conventional piezocone penetrometers, the present invention proposes a self-excited seismic wave piezocone penetrometer device. This device can perform self-excitation of seismic waves and can measure seismic wave data in real time while drilling. At the same time, by combining the tip resistance data, sidewall friction resistance data, and pore water pressure data measured by the piezocone penetrometer conical probe, it comprehensively evaluates the small-strain shear deformation characteristics and soil dynamic properties of the soil mass, providing more accurate, efficient, and comprehensive data reference and performance evaluation basis for geotechnical engineering investigation and soil property research. Description of the drawings

[0044] Figure 1 is the structural schematic diagram of the present invention;

[0045] Figure 2 is the schematic diagram of the application process of the present invention;

[0046] Figure 3 is the correlation fitting schematic diagram of the average shear wave velocity and dynamic shear modulus of different soil layers.

[0047] Reference numerals: self-excited seismic wave drill rod 1, piezocone penetrometer conical probe 2, seismic wave exciter 3, coaxial transmission cable 4, seismic wave excitation ring 5, signal conditioner 6, ground test and analysis equipment 7, data reception and processing system 8, wave velocity test system 9, friction sleeve 10, tip probe 11, three-component geophone 12, pore water pressure sensor 13, friction resistance sensor 14, tip pressure sensor 15, pore pressure filter ring 16. Detailed implementation manners

[0048] In order to make the objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the embodiments described below are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0049] As Figure 1 shown, a self-excited seismic wave piezocone penetrometer device mainly consists of an upper self-excited seismic wave drill rod 1 and a lower piezocone penetrometer conical probe 2.

[0050] The upper seismic wave self-excitation sounding rod 1 is constructed of wave-absorbing material, with a seismic wave exciter 3 and a signal conditioner 6 built therein. It is connected to the ground test and analysis equipment 7 by means of a vertically arranged coaxial transmission cable 4, thereby achieving the functions of real-time seismic wave signal conditioning and transmission.

[0051] The lower piezocone annular probe 2 is composed of a friction sleeve 10 and a cone tip probe 11. A set of three-component geophones 12 are respectively arranged at the upper and lower parts of the friction sleeve, and the three-component geophones are wrapped and isolated by wave-absorbing material sleeves; the piezocone probe 2 internally integrates a pore water pressure sensor 13, a skin friction sensor 14, and a cone tip pressure sensor 15, which are used to collect data and upload the measured data through the coaxial transmission cable. A pore pressure filter ring 16 is also arranged between the friction sleeve 10 and the cone tip probe 11.

[0052] In this embodiment, the length of the upper seismic wave self-excitation sounding rod 1 reaches 1000 mm, and it is prepared from a high-strength styrene wave-absorbing polyester material, with its wave-absorbing efficiency exceeding 80%.

[0053] The seismic wave exciter 3 is located at the upper part of the seismic wave self-excitation sounding rod 1 and 100 mm away from the top, and is arranged in a ring shape; the width of the seismic wave excitation ring 5 is set to 100 mm.

[0054] A set of three-component geophones 12 are respectively arranged at the upper and lower parts of the friction sleeve. The distance L between the two sets of three-component geophones 12 is 50 mm, and they are wrapped and isolated by high-strength styrene wave-absorbing polyester sleeves. The natural vibration frequency of the geophones is usually 10 Hz.

[0055] The cone angle of the cone tip probe 11 is 60°, and the cross-sectional area of the cone bottom is 10 cm 2 The surface area of the friction sleeve 10 is 150 cm 2 The thickness of the pore pressure filter ring 16 is 5 mm.

[0056] The self-excitation seismic wave piezocone device for evaluating the small-strain shear deformation characteristics and soil dynamic properties of soil masses in this embodiment excites seismic waves through the self-vibrating seismic wave exciter 3 built in the first sounding rod, and then relies on the three-component geophones 12 built in the piezocone probe to test the real-time seismic wave data of each stratum during the penetration process, thereby realizing the functions of seismic wave self-excitation and real-time measurement of seismic wave data while drilling, and can effectively distinguish the seismic grade, fracture development degree, and other special soil engineering properties of the stratum.

[0057] Among them, the specific process of the self-excitation seismic wave piezocone test is as follows:

[0058] a. Connect the seismic wave self-excitation probe 1 and the piezocone penetrometer probe 2, place them in the static penetrometer equipment, and perform in-situ penetration. Set the penetration speed v to 100 mm / 2 s;

[0059] b. After the entire seismic wave self-excitation probe 1 is buried in the soil, start the ground test and analysis equipment 7. The control signal regulator uses waveform modulation to generate a short-term impact signal, and set the impact signal to be emitted once every 10 s;

[0060] c. Receive the excited seismic wave signals through the two sets of three-component geophones 12 built into the probe. After confirming that the waveform is complete and correct, automatically save the data and perform the test at the next depth;

[0061] As Figure 2 shown, after each impact signal is emitted, the wave velocity test system 9 in the ground test and analysis equipment 7 calculates the shear wave velocity V S The specific method is:

[0062] a. Calculate the time difference of signal propagation:

[0063]

[0064] Among them, △t is the time difference of signal propagation;

[0065] t1 is the time when the lower three-component geophone receives the signal after this impact signal is emitted;

[0066] t2 is the time when the upper three-component geophone receives the signal after this impact signal is emitted.

[0067] b. Calculate the signal propagation distance D. Specifically, D is the sum of the distance L between the two sets of three-component geophones 12 and the penetration distance S of the probe during the Δt time,

[0068] Then the penetration distance is:

[0069]

[0070] In the formula, S is the penetration distance of the probe; is the set penetration speed.

[0071] Then the propagation distance:

[0072]

[0073] In the formula, D is the signal propagation distance; L is the distance between the two sets of three-component geophones.

[0074] c. Calculate the shear wave velocity V S :

[0075]

[0076] In the formula, V S is the shear wave velocity, in m / s.

[0077] The data receiving and processing system 8 in the ground test analysis device 7 can be used to calculate the dynamic shear modulus of the current soil layer according to the shear wave velocity Vs calculated by the wave velocity test system 9:

[0078]

[0079] In the formula, G max represents the dynamic shear modulus of the soil mass, in MPa; ρ represents the natural density of the soil layer, in g / cm 3 . As Figure 3 shown is the schematic diagram of the correlation fitting between the shear wave velocity and the dynamic shear modulus of different soil layers.

[0080] The data receiving and processing system 8 can also be used to calculate the surface wave velocity of the current soil layer according to the shear wave velocity Vs calculated by the wave velocity test system 9 :

[0081]

[0082] In the formula, μ represents the Poisson's ratio of the soil mass. For sandy soil, μ takes 0.20 - 0.25, and for clay, μ takes 0.25 - 0.45.

[0083] In addition, the data receiving and processing system 8 can perform processing and analysis operations based on various data of the seismic wave obtained by the wave velocity test system 9, and then realize the accurate discrimination of the soil layer and the effective identification of the soil properties.

[0084] The data receiving and processing system 8 can also integrate various data of the in-situ measured seismic wave with the cone tip resistance data, side wall friction resistance data, and pore water pressure data measured by the piezocone penetrometer 2 of the piezocone, comprehensively evaluate the small-strain shear deformation characteristics and soil dynamic properties of the soil mass, so as to provide key basic data and scientific decision-making basis for the exploration, design, and construction of geotechnical engineering.

[0085] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A self-excited seismic wave static cone penetration test device, characterized in that, It includes a self-exciting seismic wave sounding rod, a piezocone penetrometer probe, and a ground test and analysis device; Among them, the self-exciting seismic wave sounding rod and the piezocone penetrometer probe are connected vertically in sequence; Inside the self-exciting seismic wave sounding rod, a seismic wave exciter is provided; The piezocone penetrometer probe includes a friction sleeve and a cone tip probe that are connected vertically in sequence; A set of three-component geophones are respectively provided at the upper and lower parts of the friction sleeve; The three-component geophones, the seismic wave exciter are electrically connected to the ground test and analysis device.

2. The self-excited seismic wave static cone penetration test device according to claim 1, characterized in that, The material of the self-exciting seismic wave sounding rod is an absorbing material; the three-component geophones are wrapped and isolated by an absorbing material sleeve.

3. The self-excited seismic wave static cone penetration test device according to claim 1, characterized in that, The piezocone penetrometer probe is internally integrated with a pore water pressure sensor, a skin friction sensor, and a cone tip pressure sensor; The pore water pressure sensor, the skin friction sensor, and the cone tip pressure sensor are electrically connected to the ground test and analysis device.

4. A self-excited seismic wave static cone penetration test device according to claim 1, characterized in that A pore pressure filter ring is also arranged between the friction sleeve and the cone tip probe.

5. A self-excited seismic wave static cone penetration testing device according to claim 1, characterized in that The detection process of the seismic piezocone penetration testing device is as follows: The connected self-exciting seismic wave sounding rod and the piezocone penetrometer probe are in-situ penetrated through a piezocone penetration device at a penetration speed of v; After the seismic piezocone penetration testing device is inserted into the soil, the ground test and analysis device controls the seismic wave exciter to intermittently emit impact signals; After each impact signal is emitted, the ground test and analysis device calculates soil layer parameters according to the signals received from the two sets of three-component geophones.

6. The self-excited seismic wave static cone penetration testing device according to claim 5, characterized in that, The soil layer parameters include the dynamic shear modulus of the soil mass ; Specifically, The calculation steps are as follows: Calculate the time difference of signal propagation: Among them, △t is the time difference of signal propagation; t1 is the time when the lower three-component geophone receives the signal after this impact signal is emitted; t2 is the time when the upper three-component geophone receives the signal after this impact signal is emitted; Calculate the signal propagation distance: Among them, D is the signal propagation distance; L is the distance between the two sets of three-component geophones; S is the penetration distance of the sounding rod within the time of Δt; Calculate the shear wave velocity: Among them, V S is the shear wave velocity; Calculate the dynamic shear modulus of the soil body: Among them, represents the natural density of the soil layer.

7. The self-excited seismic wave static cone penetration test device according to claim 6, characterized in that, The soil layer parameters include the surface wave velocity of the soil layer ; Specifically, The calculation method is as follows: Among them, μ represents the Poisson's ratio of the soil body.

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