Novel heavy dynamic sounding method for foundation soil dynamic characteristic in-situ test

Abstract

The invention discloses a novel heavy dynamic sounding method for foundation soil dynamic characteristic in-situ testing. The novel heavy dynamic sounding method comprises the steps that A, a small acceleration sensor is installed on a heavy dynamic sounding rod steel anvil; b, performing an indoor calibration test, and establishing a function relationship between a dynamic penetration acceleration parameter and a foundation soil dynamic parameter; c, carrying out novel heavy dynamic penetration test on the to-be-detected foundation; d, comprehensively processing the acquired heavy dynamic sounding hammering number and acceleration data; and E, calculating the static and dynamic parameters of the foundation soil according to the function relationship in the step B. The method is easy to implement and simple and convenient to operate, acceleration parameters in the penetration process are obtained by installing a small acceleration sensor on the heavy dynamic sounding rod, static and dynamic parameters of foundation soil are calculated according to the established empirical relation between the acceleration parameters and the dynamic parameters of the foundation soil, and the problem that when the foundation soil is detected through existing heavy dynamic sounding, the static and dynamic parameters of the foundation soil cannot be detected is solved. And power parameters cannot be provided.

Description

Technical Field

[0001] The present invention belongs to the technical field of heavy-duty dynamic penetration testing for in-situ testing of foundation soil, and more specifically relates to a novel heavy-duty dynamic penetration method for in-situ testing of dynamic properties of foundation soil, which is suitable for engineering property testing of foundation soil, especially miscellaneous fill foundation. Background Art

[0002] For some important civil engineering projects and civil engineering projects in areas with active seismic activity, the dynamic parameters of foundation soil are crucial to evaluating the seismic performance of the project. However, currently, except for geophysical exploration methods and indoor test methods, there is a lack of testing methods for the dynamic parameters of foundation soil that can be used for on-site testing.

[0003] The geophysical test method is an indirect measurement method. The test results must be verified by drilling data and are greatly affected by factors such as groundwater level and uniformity, so the accuracy is difficult to guarantee. Indoor tests require sampling from the site. The disadvantages of soil sampling, large disturbance, and high cost also limit the application of this method. Heavy-duty dynamic penetration is an in-situ test method often used for foundation soils such as sand, gravel, miscellaneous fill, and extremely soft rock. According to empirical data, static parameters such as density, deformation modulus, and foundation bearing capacity of the foundation soil can be obtained, but dynamic parameters cannot be obtained. In the heavy-duty dynamic penetration test, when the cone probe is continuously hammered into the foundation soil, the touch rod will vibrate to a certain extent. The physical and mechanical properties of the foundation soil are different, and the vibration characteristics are also different. Therefore, the relationship between the vibration characteristic parameters of the penetration rod and the dynamic parameters of the foundation soil can be established to obtain the foundation dynamic parameters required for theoretical analysis.

[0004] Therefore, it is necessary to develop a new in-situ testing method to overcome the problems of insufficient accuracy, high testing cost, and small amount of data in the existing foundation soil dynamic parameter testing methods, so as to provide rich and reliable in-situ data for the seismic performance evaluation of civil engineering projects. Summary of the invention

[0005] The purpose of the present invention is to provide a new heavy-duty dynamic probing method for in-situ testing of the dynamic characteristics of foundation soil. The method is easy to implement and simple to operate. A small acceleration sensor is installed on the heavy-duty dynamic probing rod to obtain the acceleration parameters of the penetration process. The static and dynamic parameters of the foundation soil are calculated based on the established empirical relationship between the acceleration parameters and the dynamic parameters of the foundation soil. This solves the technical problem that the existing heavy-duty dynamic probing cannot provide dynamic parameters when detecting foundation soil.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0007] A new heavy-duty dynamic penetration method for in-situ testing of dynamic properties of foundation soil, the method comprising the following steps:

[0008] Step 1: Install a small accelerometer on the heavy-duty dynamic sounding rod: On the steel anvil of the heavy-duty dynamic sounding rod, a small acceleration sensor is completely attached to the sounding rod by welding a mounting frame, and a data line of the acceleration sensor is connected to a data acquisition instrument; a small accelerometer is installed on the upper sounding rod, and data is recorded using a data acquisition instrument;

[0009] Step 2: Establish the functional relationship between the dynamic penetration acceleration parameters and the dynamic parameters of the foundation soil: Through indoor calibration tests, establish the functional relationship between the heavy dynamic penetration acceleration parameters (maximum acceleration, attenuation coefficient, etc.) and the dynamic parameters of the foundation soil (foundation stiffness, damping ratio, vibration mass) of sand, gravel, miscellaneous fill and extremely soft rock foundation soils:

[0010] P N =f(A N )

[0011] Where P N is the dynamic parameter of foundation soil;

[0012] A N It is the acceleration parameter of heavy-duty dynamic penetration;

[0013] f is the functional relationship obtained from the calibration test;

[0014] Step 3: Conduct a new type of heavy-duty dynamic penetration test: Conduct a new type of heavy-duty dynamic penetration test on the foundation to be tested, record the number of heavy-duty dynamic penetration hammer strikes at a depth of about 10 cm, and record the acceleration value obtained during each dynamic penetration hammer strike;

[0015] Step 4: Comprehensively process the heavy-duty dynamic penetration test hits and acceleration data: Comprehensively process the collected heavy-duty dynamic penetration test hits and acceleration data to obtain the number of hammer strikes and acceleration parameters (maximum acceleration value, attenuation coefficient, etc.) at a depth of about 10 cm;

[0016] Step 5: Calculate the static and dynamic parameters of the foundation soil based on the existing functional relationship: Substitute the acceleration parameter A obtained in step 4 into N Substitute the functional relationship between the heavy dynamic penetration acceleration parameter and the foundation soil dynamic parameter P N =f(A N ) to obtain the dynamic parameters of the foundation soil (foundation stiffness, damping ratio, parametric mass, etc.); at the same time, consult the relationship between existing empirical data and the number of hammer blows to obtain parameters such as the density, deformation parameters and foundation bearing capacity of the foundation soil. For example, in the "Fifth Edition of the Engineering Geology Manual", the density of sand can be obtained by looking up Table 3-2-7, the characteristic values ​​of the foundation bearing capacity of sandy soil and crushed stone soil can be obtained by looking up Table 3-2-28, and the deformation modulus of round gravel and pebble soil can be determined by looking up Table 3-2-24.

[0017] Through the technical measures of the above five steps: the most critical one is step one, by installing a small acceleration sensor, the vibration characteristic parameters of the foundation soil during the hammering process are obtained. Although this method seems simple, it is a new method for in-situ testing of foundation soil dynamics based on the principle of foundation soil dynamic parameter testing. It can quickly and conveniently obtain the in-situ dynamic test characteristic parameters of the foundation soil, laying the foundation for solving the problem of direct, rapid and effective testing of foundation soil dynamic parameters, and effectively solving the bottleneck diameter existing in the prior art.

[0018] The technical progress of the present invention is mainly reflected in two aspects. On the one hand, a small acceleration sensor is used and directly installed on a heavy-duty dynamic probing rod, so that a large number of foundation soil vibration characteristic parameters can be collected while obtaining the number of hammer blows; on the other hand, through calibration tests supplemented by machine learning methods, the functional relationship between the heavy-duty dynamic probing acceleration parameters (maximum acceleration, attenuation coefficient, etc.) of foundation soils such as sand, gravel, miscellaneous fill and extremely soft rock and the dynamic parameters of the foundation soil (foundation stiffness, damping ratio, parametric mass) is established respectively, and the more data accumulated, the more accurate and richer the parameters are.

[0019] The main difference between the present invention and the prior art is that the present invention fills the gap of the current lack of testing methods and technologies that can directly collect in-situ foundation soil dynamic parameters in large quantities within the entire survey depth range.

[0020] Through the above-mentioned technical measures, a new type of heavy-duty dynamic probing device for in-situ testing of dynamic characteristics of foundation soil is obtained. The device consists of a guide rod, a core hammer, a steel anvil and a hammer pad, a probing rod, a conical probe, a mounting frame, a small acceleration sensor, a data cable, a data acquisition instrument, foundation soil and the ground. The connection relationship is as follows: the core hammer is connected to the steel anvil and the hammer pad through the guide rod, the probing rod is connected to the guide rod through the ground, the probing rod is connected to the foundation soil, the steel anvil and the hammer pad are respectively equipped with a mounting frame, a small acceleration sensor and a data cable, and the data cable is connected to the data acquisition instrument.

[0021] Compared with the prior art, the present invention has the following advantages and effects:

[0022] The present invention obtains acceleration parameters of the penetration process by installing a small acceleration sensor on a heavy-duty dynamic probing rod, and infers the static and dynamic parameters of the foundation soil based on the established empirical relationship between the acceleration parameters and the dynamic parameters of the foundation soil, thereby solving the problem that the existing heavy-duty dynamic probing cannot provide dynamic parameters when detecting foundation soil.

[0023] The device of the present invention collects dynamic data by installing a small accelerometer, has the advantages of simple and reliable structure, small size, and easy operation, and achieves the effect of real-time, accurate and continuous collection of dynamic parameters with rich data volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The flowchart is a new heavy-duty dynamic penetration method for in-situ testing of dynamic properties of foundation soil.

[0025] Figure 2 The figure is a schematic diagram of a new heavy-duty dynamic penetration method for in-situ testing of dynamic properties of foundation soil.

[0026] In the figure: 1. guide rod, 2. core hammer, 3. steel anvil and hammer pad, 4. feeler rod, 5. cone probe, 6. mounting frame, 7. small acceleration sensor (ARF-20A, Japan TML), 8. data cable, 9. data acquisition instrument (G01NET-3D high-precision dynamic data acquisition instrument), 10. foundation soil, 11. ground. DETAILED DESCRIPTION

[0027] The present invention is further described with reference to the following device drawings and specific embodiments.

[0028] Embodiment 1:

[0029] like Figure 1 and Figure 2 As shown in the figure, a new heavy-duty dynamic penetration method for in-situ testing of dynamic properties of foundation soil is implemented as follows:

[0030] A. Install a small accelerometer on the heavy-duty dynamic sounding rod: On the steel anvil of the heavy-duty dynamic sounding rod, a small acceleration sensor is completely attached to the sounding rod by welding the mounting frame. The size of the accelerometer is 14mm×14mm×18mm. Connect the data line of the acceleration sensor to the dynamic data acquisition instrument. Install a small accelerometer on the upper sounding rod and use the data acquisition instrument to record the data.

[0031] B. Establish the functional relationship between the acceleration parameters of dynamic penetration and the dynamic parameters of foundation soil: Conduct indoor calibration tests, that is, obtain the dynamic parameters of foundation soil through sampling indoor tests, and use data analysis methods such as machine learning to establish the quantitative relationship between the vibration characteristic parameters obtained on site and the dynamic parameters. Establish the functional relationship between the acceleration parameters of heavy dynamic penetration (maximum acceleration, attenuation coefficient, etc.) and the dynamic parameters of foundation soil (foundation stiffness, damping ratio, vibration mass) of sand, gravel, miscellaneous fill and extremely soft rock foundation soils, P N =f(A N ).

[0032] C. Conduct a new type of heavy-duty dynamic penetration test: Conduct a new type of heavy-duty dynamic penetration test on the foundation to be tested, record the number of heavy-duty dynamic penetration hammer strikes for every 10cm hammer depth, and record the acceleration value obtained during each dynamic penetration hammer strike.

[0033] D. Comprehensive processing of heavy-duty dynamic penetration test hits and acceleration data: Comprehensively process the collected heavy-duty dynamic penetration test hits and acceleration data to obtain the number of hammer strikes per 10 cm depth and the corresponding acceleration parameter A. N (maximum acceleration value, attenuation coefficient, etc.).

[0034] E. Calculate the static and dynamic parameters of the foundation soil based on the existing functional relationship: obtain the above acceleration parameter A N Substitute the functional relationship between the heavy dynamic penetration acceleration parameter and the foundation soil dynamic parameter P N =f(A N ) to obtain the dynamic parameters of the foundation soil (foundation stiffness, damping ratio, parametric mass, etc.); at the same time, by consulting the relationship between existing empirical data and the number of hammer blows, the density of the foundation soil, deformation parameters and foundation bearing capacity and other parameters can be obtained. For example, in the "Engineering Geology Handbook Fifth Edition", the density of sand can be obtained by looking up Table 3-2-7, the characteristic values ​​of the foundation bearing capacity of sandy soil and crushed stone soil can be obtained by looking up Table 3-2-28, and the deformation modulus of round gravel and pebble soil can be determined by looking up Table 3-2-24.

[0035] Embodiment 2:

[0036] A novel heavy-duty dynamic sounding device for in-situ testing of dynamic characteristics of foundation soil, the device comprises a guide rod 1, a core hammer 2, a steel anvil and a hammer pad 3, a sounding rod 4, a cone probe 5, a mounting frame 6, a small acceleration sensor 7, a data line 8, a data acquisition instrument 9, foundation soil 10, and a ground 11. The connection relationship is as follows: the core hammer 2 transmits hammering energy to the hammer pad and the steel anvil through the guide rod 1, the sounding rod 4 is connected with the hammer pad and the steel anvil 3, passes through the ground 11 and is connected with the cone probe 5, and each hammering energy is transmitted to the cone probe 5, so that the depth of the cone probe 5 continuously entering the foundation soil 10 increases continuously, the sounding rod 4 is connected with the foundation soil 10, and the mounting frame 6 and the small acceleration sensor 7 are respectively installed on the hammer pad and the steel anvil 3, the data line 8 is connected with the small acceleration sensor 7, the data acquisition instrument 9 is connected with the data line 8, and the automatic acquisition instrument 9 collects and stores the vibration parameters measured by the small acceleration sensor 7.

Claims

1. A new heavy-duty dynamic penetration method for in-situ testing of dynamic properties of foundation soil, characterized by: The method comprises the following steps: A. Install a small accelerometer on the heavy-duty dynamic sounding rod: On the steel anvil of the heavy-duty dynamic sounding rod, attach the acceleration sensor to the sounding rod by welding the mounting frame, and connect the data line of the acceleration sensor to the data acquisition instrument; B. Establish the functional relationship between the acceleration parameters of dynamic penetration and the dynamic parameters of foundation soil: Through indoor calibration tests, the functional relationship between the acceleration parameters of heavy dynamic penetration and the dynamic parameters of foundation soil is established for sand, gravel, miscellaneous fill and extremely soft rock foundation soil: P N =f(A N ) Where: P N is the dynamic parameter of foundation soil; A N It is the acceleration parameter of heavy-duty dynamic penetration; f is the functional relationship obtained from the calibration test; C. Conduct a new type of heavy-duty dynamic penetration test: Conduct a new type of heavy-duty dynamic penetration test on the foundation to be tested, record the number of heavy-duty dynamic penetration hammer strikes for every 10cm hammer strike depth, and record the acceleration value obtained during each dynamic penetration hammer strike; D. Comprehensive processing of the number of heavy-duty dynamic penetration test hits and acceleration data: Comprehensively process the collected heavy-duty dynamic penetration test hits and acceleration data to obtain the number of hammer strikes and acceleration parameters per 10 cm depth; E. Calculate the static and dynamic parameters of the foundation soil based on the existing functional relationship: Substitute the acceleration parameter A obtained in step (D) N Substitute the functional relationship between the heavy dynamic penetration acceleration parameter and the foundation soil dynamic parameter P N =f(A N ) to obtain the dynamic parameters of the foundation soil: foundation stiffness, damping ratio, and parametric mass; at the same time, by consulting the existing empirical data and the relationship between the number of hammer blows, the density of the foundation soil, deformation parameters, and foundation bearing capacity parameters are obtained.

2. A novel heavy-duty dynamic penetration method for in-situ testing of dynamic properties of foundation soil according to claim 1, characterized in that: A small accelerometer is installed on the upper probe rod in the step (A), and a data acquisition instrument is used to record data.

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