AU2020233718B2

AU2020233718B2 - In-situ soil parameter measuring device based on pressure penetration

Info

Publication number: AU2020233718B2
Application number: AU2020233718A
Authority: AU
Inventors: Zeming WANG; Zhongtao WANG; Long Yu; Heyue ZHANG
Original assignee: Dalian University of Technology
Current assignee: Dalian University of Technology
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2022-08-25
Anticipated expiration: 2040-09-17
Also published as: AU2020233718A1

Abstract

The present invention discloses an in-situ soil parameter measuring device based on pressure penetration, comprising a working cylinder, a loading and data acquiring system, a rod, a penetrometer, a pressurizing capsule and a pressurizing component. For testing, the working cylinder is inserted into the soil, the loading and data acquiring system controls the rod to slowly load until the penetrometer is in contact with the surface of the soil, the pressurizing component is used to input a pressurized medium into the pressurizing capsule, water trapped in the working cylinder is extruded by the expansion of the pressurizing capsule to improve the accuracy of the test results, the pressure in the pressurizing capsule is controlled by the pressurizing component until the soil inside the working cylinder is subjected to a uniform design load imposed by the pressurizing capsule, and the loading and data acquiring system controls the rod to load and unload, so as to carry out the soil characteristics test. In addition, the in-situ soil parameter measuring device based on the pressure penetration of the present invention can also be used for the in-situ soil consolidation characteristics test. 2 111 6 15 5 1 3 14 4 FIG.1 1 .5 6 5 FIG2

Description

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FIG.1

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FIG2

IN-SITU SOIL PARAMETER MEASURING DEVICE BASED ON PRESSURE PENETRATION

TECHNICAL FIELD The present invention relates to the technical field of geotechnical, geological and environmental research, in particular to an in-situ soil body parameter measuring device based on pressure penetration.

BACKGROUND The geotechnical in-situ test refers to the survey and testing of the engineering properties of the soil in situ. The geotechnical in-situ test can determine the engineering mechanical properties of undisturbed soil samples that are difficult to obtain; it can avoid the influence of stress release during the sampling process; it has a wide range of influence and strong representativeness. Cone penetration test (CPT, CPTU, etc.) and full-flow penetration test are currently widely used in-situ tests, which are fast, direct and accurate. The common penetrometers are T-bar penetrometer and ball-bar penetrometer. The measurement principle is to statically press the penetrometer into the soil at a constant speed. When the soil around the penetrometer reaches a state of complete backflow, the soil pressures on the penetrometer's upper surface and the lower surface are almost equal. There is no need to modify the overburden soil pressure and the soil shear strength and other parameters can be directly analyzed through the response force and pore pressure measured by the sensor. However, in the actual penetration process, a cavity will be formed above the penetrometer at a relative shallow penetration depth. At this time, the soil around penetrometer has not flow back. As the penetration depth increases, the soil will gradually flow back and the cavity will be closed with the effect of gravity. The full-flow mechanism only occurs when the penetration reaches deeper. In other words, the traditional full-flow penetrometer can not accurately measure the physical characteristic parameters of the shallow soil. Therefore, how to change the current situation that the full-flow penetrometer can not accurately measure the physical characteristic parameters of the shallow soil has become an W urgent problem for those skilled in the art.

SUMMARY The object of the present invention is to provide an in-situ soil parameter measuring device based on pressure penetration to solve the above problems in the prior art and improve the accuracy of in-situ soil engineering parameter characteristic measurement.

In order to achieve the above object, the present invention provides the following solutions: the present invention provides an in-situ soil parameter measuring device based on pressure penetration, comprising a working cylinder, a loading and data acquiring system, a rod, a penetrometer, a pressurizing capsule and a pressurizing component, wherein the working cylinder is a hollow structure with an opening at the bottom; one end of the rod is connected to the loading and data acquiring system, the loading and data acquiring system is capable of driving the rod to reciprocate; the other end of the rod slidably extends into the working cylinder and is connected to the penetrometer. A force sensor and a pore pressure sensor are built in the penetrometer. The pressurizing capsule is provided in the working cylinder, the pressurizing capsule is provided around the rod, the pressurizing capsule is located at the top of the penetrometer, the pressurizing capsule is in communication with the pressurizing component, the pressurizing capsule is made of flexible material, the working cylinder is further provided with a communication port, and the communication port is in communication with the external environment. Preferably, the pressurizing capsule is a hollow structure, and the rod is connected with the penetrometer through the hollow part of the pressurizing capsule. Preferably, the pressurizing capsule has a hollow cylindrical structure, and the inner diameter of the pressurizing capsule matches the outer diameter of the rod. Preferably, the pressurizing component is a pressurizing water pump, and the pressurizing water pump is in communication with the pressurizing capsule through a pump tube. Preferably, the rod is provided coaxially with the working cylinder, the top of the working cylinder is connected with a fixed ring and a protection cylinder, the protection cylinder is in communication with the working cylinder, the rod extends into the working cylinder through the protection cylinder, a sealing ring is provided between the rod and the protection cylinder, the !5 fixed ring is sleeved outside the protection cylinder, the fixed ring is connected with the working cylinder, and the loading and data acquiring system is located at the top of the protection cylinder. Preferably, the communication port is located at the top of the working cylinder. Preferably, the inner wall of the working cylinder is provided with a plurality of drainage grooves, the drainage grooves are provided in parallel to the axis of the working cylinder, the drainage grooves are evenly spaced, and the drainage grooves are recessed in a direction away from the axis of the working cylinder. Preferably, the penetrometer is a ball-bar penetrometer, a T-bar penetrometer, a cone penetrometer (for cone penetration test) or a vane penetrometer. Preferably, the diameter of the working cylinder is not less than 5 times the diameter of the penetrometer. Preferably, the bottom of the working cylinder is provided with an insertion part, the insertion part is in the shape of an inverted truncated cone, and the end of the insertion part with a larger diameter is connected to the working cylinder. Compared with the prior art, the present invention has achieved the following technical effects: the in-situ soil parameter measuring device based on pressure penetration of the present invention comprises a working cylinder, a loading and data acquiring system, a rod, a penetrometer, a pressurizing capsule and a pressurizing component, wherein the working cylinder is a hollow structure with an opening at the bottom, one end of the rod is connected to the loading and data acquiring system, the loading and data acquiring system is capable of driving the rod to reciprocate, the other end of the rod slidably extends into the working cylinder and is connected to the penetrometer, a force sensor and a pore pressure sensor are built in the penetrometer, the pressurizing capsule is provided in the working cylinder, the pressurizing capsule is provided around the rod, the pressurizing capsule is located at the top of the penetrometer, the pressurizing capsule is in communication with the pressurizing component, the pressurizing capsule is made of flexible material, the working cylinder is further provided with a communication port, and the communication port is in communication with the external environment. When the in-situ soil parameter measuring device based on pressure penetration of the present invention is used, the working cylinder is inserted into the soil the loading and data acquiring system controls the rod to slowly load until the penetrometer is in contact with the surface of the soil, and the pressurizing component is used to input a pressurized medium into the pressurizing capsule. For the underwater condition, the water trapped inside the working cylinder will be extruded with the expansion of the pressurizing capsule to improve the accuracy of the test results. The pressure in the pressurizing capsule is controlled by the !5 pressurizing component until the soil surface inside the working cylinder is subjected to a uniform design load imposed by the pressurizing capsule. The loading and data acquiring system controls the rod to load and unload, so as to carry out the soil body characteristic parameter test. In addition, the in-situ soil parameter measuring device based on the pressure penetration of the present invention can also be used for the in-situ soil consolidation characteristics test. After the cyclic penetration test is performed, the rod and the penetrometer are withdrawn to the position of the soil surface. The pressurized medium in the pressurizing capsule is released until the hydrostatic pressure or the specified pressure value is reached, Standing for a period of time, so that the disturbed soil is consolidated under certain consolidation pressure. After the consolidation, a pressurized medium is introduced into the pressurizing capsule again until the design pressure is reached, and then the rod and penetrometer are controlled to perform another pressure penetration test to measure the soil strength with different degrees of consolidation. The pore pressure sensor and the force sensor built into the penetrometer are used to measure the pore pressure and response force throughout the test to analyze the in-situ soil consolidation characteristics.

BRIEF DESCRIPTION OF THE DRAWINGS In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings that need to be used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only a part of the embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without paying creative labor. FIG. 1 is a working schematic diagram of an in-situ soil parameter measuring device based on pressurepenetration according to the present invention; FIG. 2 is a schematic diagram of a part of the structure of an in-situ soil parameter measuring device based on pressure penetration according to the present invention; FIG. 3 is a schematic diagram of the structure of different types of penetrometers of an in-situ soil parameter measuring device based on pressure penetration according to the present invention; FIG. 4 is a cut-away schematic diagram of a part of the structure of an in-situ soil parameter measuring device based on pressure penetration according to the present invention. In the figures, 1, working cylinder, 2, loading and data acquiring system, 3, rod, 4, penetrometer, 5, pressurizing capsule, 6, pressurized component, 7, pore pressure sensor, 8, force sensor, 9, fixed ring, 10, protective cylinder, 11, sealing ring, 12, communication port, 13, drainage groove, 14, insertion part, 15, pump tube. !5 DESCRIPTION OF THE EMBODIMENTS The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without paying creative labor shall fall within the protection scope of the present invention. The object of the present invention is to provide an in-situ soil parameter measuring device based on pressure penetration to solve the above problems in the prior art and improve the accuracy in measuring the in-situ soil engineering parameters.

In order to make the above object, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. Refer to FIGS. 1-4, wherein FIG. 1 is a working schematic diagram of an in-situ soil parameter measuring device based on pressure penetration according to the present invention; FIG. 2 is a schematic diagram of a part of the structure of an in-situ soil parameter measuring device based on pressure penetration according to the present invention; FIG. 3 is a schematic diagram of the structure of different types of penetrometers of an in-situ soil parameter measuring device based on pressure penetration according to the present invention; FIG. 4 is a cut-away schematic diagram of a part of the structure of an in-situ soil parameter measuring device based on pressure penetration according to the present invention. First of all, it should be noted that the in-situ soil parameter measuring device based on pressure penetration of the present invention is suitable for both dry soil and underwater soil parameter measurement. Because the situation in underwater soil parameter measurement is more complicated, in the following specific embodiments, the underwater soil parameter measurement is taken as an example to explain the in-situ soil parameter measuring device based on the pressure penetration test of the present invention. The present invention provides an in-situ soil parameter measuring device based on pressure penetration, comprising a working cylinder 1, a loading and data acquiring system 2, a rod 3, a penetrometer 4, a pressurizing capsule 5 and a pressurizing component 6, wherein the working cylinder 1 is a hollow structure with an opening at the bottom, one end of the rod 3 is connected to the loading and data acquiring system 2, the loading and data acquiring system 2 is capable of driving the rod 3 to reciprocate, the other end of the rod 3 slidably extends into the working cylinder 1 and is connected to the penetrometer 4, a force sensor 8 and a pore pressure sensor 7 are built in the penetrometer 4, the pressurizing capsule 5 is provided in the working cylinder 1, the pressurizing capsule 5 is provided around the rod 3, the pressurizing capsule 5 is located at the top of the penetrometer 4, the pressurizing capsule 5 is in communication with the pressurizing component 6, the pressurizing capsule 5 is made of flexible material, the working cylinder 1 is further provided with a communication port 12, and the communication port 12 is in communication with the external environment. When the in-situ soil parameter measuring device based on pressure penetration of the present invention is used, the working cylinder 1 is installed to a certain depth underwater, the loading and data acquiring system 2 controls the rod 3 to slowly load until the penetrometer 4 is in contact with the surface of the soil, and the pressurizing component 6 is used to input a pressurized medium into the pressurizing capsule 5. Water trapped in the working cylinder 1 is extruded with the expansion of the pressurizing capsule 5 to improve the accuracy of the test results, the pressure in the pressurizing capsule 5 is controlled by the pressurizing component 6 until the soil surface inside the working cylinder 1 is subjected to a uniform design load imposed by the pressurizing capsule 5, and the loading and data acquiring system 2 controls the rod 3 to load and unload, so as to carry out the soil characteristic parameter test. In addition, the in-situ soil parameter measuring device based on the pressure penetration of the present invention can also be used for the in-situ soil consolidation characteristics test. After the cyclic penetration test is performed, the rod 3 and the penetrometer 4 are withdrawn to the position of the soil surface, the pressurized medium in the pressurizing capsule 5 is released until the hydrostatic pressure or the specified pressure value is reached, standing for a period of time (the standing time is determined according to the test requirements). After the consolidation, a pressurized medium is introduced into the pressurizing capsule 5 again until the design pressure is reached, and then the rod 3 and penetrometer 4 are controlled to perform another pressure penetration test to measure the soil strength with different degrees of consolidation. The pore pressure sensor 7 and the force sensor 8 built into the probe 4 are used to measure the pore pressure and counter-force throughout the test to analyze the in-situ soil consolidation characteristics. In order to perform an uniform pressure to the test soil, the pressurizing capsule 5 has a hollow structure, and the rod 3 is connected with the penetrometer 4 through the hollow part of the pressure capsule 5. In this embodiment, the pressurizing capsule 5 has a hollow cylindrical structure, and the inner diameter of the pressurizing capsule 5 matches the outer diameter of the rod 3 to further ensure that the test soil part is under uniformly distributed pressure. It should be noted here that the pressurized medium can be a medium that can fill the !5 inside of the pressurizing capsule 5 to expand and pressurize, such as water, gas, etc. In this specific embodiment, the pressurizing component 6 is a pressurizing water pump, and the pressurizing water pump is in communication with the pressurizing capsule 5 through a pump tube 15. The pressurizing water pump pumps water into the pressurizing capsule 5 to apply pressure to the test soil part. It should be noted that the present invention further provides a control system, which is connected to the loading and data acquiring system 2 and the pressurizing water pump, which is convenient for the operator to control. Because the control system belongs to the usual means of those skilled in the art, it will not be described in detail here. Specifically, the rod 3 is coaxially provided with the working cylinder 1, the top of the working cylinder 1 is connected with a fixed ring 9 and a protection cylinder 10, the protection cylinder 10 is in communication with the working cylinder 1, and the rod 3 extends into the working cylinder 1 through the protection cylinder 10. The protection cylinder 10 can protect the rod 3 from external interference to ensure the smooth progress of the test. A sealing ring 11 is provided between the probe rod 3 and the protection cylinder 10. The sealing ring 11 can prevent the soil from squeezing into the protective cylinder 10 during the pressure penetration, and affecting the test result. The fixed ring 9 is sleeved outside the protection cylinder 10, and the fixed ring 9 is connected with the working cylinder 1 to further improve the stability of the protective cylinder 10 and the reliability of the device. The loading and data acquiring system 2 is located at the top of the protection cylinder 10. In addition, the communication port 12 is located at the top of the working cylinder 1 to facilitate the smooth discharge of water trapped in the working cylinder 1 during device installation and avoid water entering the working cylinder 1 during operation. More specifically, the inner wall of the working cylinder 1 is provided with a plurality of drainage grooves 13, the drainage grooves 13 are provided in parallel to the axis of the working cylinder 1, the drainage grooves 13 are evenly spaced, and the drainage grooves 13 are recessed in a direction away from the axis of the working cylinder 1. The recessed drainage grooves 13 have two potential benefits, on the one hand facilitates the working cylinder 1 to penetrate deeper into the soil to provide the anti-pull force required for work; on the other hand, for underwater condition (such as measurement of soil parameters of the seabed or the riverbed), the water trapped inside the working cylinder Ican be smoothly discharged through the drainage groove 13 after the pressurizing capsule 5 expands to a certain volume, so that the pressurizing capsule 5 is in full contact with the underwater soil body surface to provide better and more flexible overburden pressure. It needs to be emphasized here is that the height of the working cylinder 1 is determined according to the site conditions, ensuring that the working area is !5 reserved after the working cylinder 1 penetrates to a certain depth wheresufficient anti-pull force can be provided to keep the entire experimental device remains stable during operation. When measuring the parameters of dry soil , the drainage groove 13 can be used to discharge gas. The penetrometer 4 and the rod 3 can be detachably connected. Different types of penetrometers 4 can be selected for different geotechnical tests. The penetrometer 4 includes but not limited to a ball-bar penetrometer, a T-bar penetrometer, a cone penetrometer (for CPT) or a vane penetrometer. The T-bar penetrometer and the ball-bar penetrometer can be used in the cyclic penetration test to measure the soil shear strength and strain softening parameters. In addition to measuring the soil shear strength and strain softening parameters (the vane penetrometer can be used to measure the sensitivity of clay), the cone penetrometer and the vane penetrometer can also be used to measure the friction angle of the soil by changing the overburden pressure. Further, the diameter of the working cylinder 1 is not less than 5 times the diameter of the penetrometer 4 to reduce, or even eliminate the influence of boundary effects. Furthermore, the bottom of the working cylinder 1 is provided with an insertion part 14, the insertion part 14 is in the shape of an inverted truncated cone, and the end of the insertion part 14 with a larger diameter is connected to the working cylinder 1. The insertion part 14 is provided to facilitate the working cylinder 1 to penetrate into the soil. In actual applications, the installation method of the working cylinder 1 is selected according to the site conditions. For example, for land soil, the working cylinder 1 can be penetrated into the soil to a specified depth by means of external pressure, such as by means of foot pedaling; for underwater soil, such as seabed soil or riverbed soil, negative suction pressure cylinders or other loading methods can be used to assist in installation, so that the working cylinder 1 and the pressurizing capsule 5 are pressed into the soil together. The in-situ soil parameter measuring device based on the pressure penetration test of the present invention is suitable for accurate measurement of the in-situ soil engineering parameter characteristics (such as soil shear strength, internal friction angle, cohesive soil sensitivity, etc.). The pressure capsule 5 flexibly applies the overburden pressure to the surface of the soil, which can achieve a full-flow penetration test in the whole process, and more accurate measurement of the strength and softening characteristics of the in-situ soil (such as sensitivity). the in-situ soil friction angle can be measured by changing the overburden pressure on the soil surface, The present invention can also be used for in-situ soil consolidation characteristics test. After the initial cyclic penetration test , the rod 3 and penetrometer 4 are withdrawn to the position of soil surface (which can also be placed at a specified depth, and the pore pressure sensor 7 built in the penetrometer 4 can be used to measure the excess pore pressure at the specified depth), the pressurized medium in the pressurizing capsule 5 is released until the hydrostatic pressure or the specified pressure value is reached, so that the disturbed soil is consolidated under specific consolidation pressure. After the design consolidation time ends, the rod 3 and penetrometer 4 are lowered, the pressurizing capsule 5 is pumped, and the full-flow penetration test is performed again to measure the strength of the soil with different consolidation degrees, providing assistance to accurate analysis of foundation bearing capacity. In the present invention, specific examples are used to illustrate the principles and implementation of the present invention. The descriptions of the above examples are only used to help understand the method and core ideas of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation and application scope. In summary, the content of this specification should not be construed as limiting the present invention.

Claims

WHAT IS CLAIMED IS:

1. An in-situ soil parameter measuring device based on pressure penetration, comprising a working cylinder, a loading and data acquiring system, a rod, a penetrometer, a pressurizing capsule and a pressurizing component, wherein the working cylinder is a hollow structure with an opening at the bottom, one end of the rod is connected to the loading and data acquiring system, the loading and data acquiring system is capable of driving the rod to reciprocate, the other end of the rod slidably extends into the working cylinder and is connected to the penetrometer, a force sensor and a pore pressure sensor are built in the penetrometer, the pressurizing capsule is provided in the working cylinder, the pressurizing capsule is provided around the rod, the pressurizing capsule is located at the top of the penetrometer, the pressurizing capsule is in communication with the pressurizing component, the pressurizing capsule is made of flexible material, the working cylinder is further provided with a communication port, and the communication port is in communication with the external environment; wherein the communication port is located at the top of the working cylinder, the inner wall of the working cylinder is provided with a plurality of drainage grooves, the drainage grooves are provided in parallel to the axis of the working cylinder, the drainage grooves are evenly spaced, and the drainage grooves are recessed in a direction away from the axis of the working cylinder.

2. The in-situ soil parameter measuring device based on pressure penetration according to claim 1, wherein the pressure capsule is a hollow structure, and the rod is connected with the penetrometer through the hollow part of the pressure capsule.

3. The in-situ soil parameter measuring device based on pressure penetration according to claim 2, wherein: the pressurizing capsule has a hollow cylindrical structure, and the inner diameter of the pressurizing capsule matches the outer diameter of the rod.

!5 4. The in-situ soil parameter measuring device based on pressure penetration according to claim 1, wherein: the pressurizing component is a pressurizing water pump, and the pressurizing water pump is in communication with the pressurizing capsule through a pump tube.

5. The in-situ soil parameter measuring device based on pressure penetration according to claim 1, wherein: the rod is provided coaxially with the working cylinder, the top of the working cylinder is connected with a fixed ring and a protection cylinder, the protection cylinder is in communication with the working cylinder, the rod extends into the working cylinder through the protection cylinder, a sealing ring is provided between the rod and the protection cylinder, the fixed ring is sleeved outside the protection cylinder, the fixed ring is connected with the working cylinder, and the loading and data acquiring system is located at the top of the protection cylinder.

6. The in-situ soil parameter measuring device based on pressure penetration according to claim 1, wherein the penetrometer is a ball-bar penetrometer, a T-bar penetrometer, a cone penetrometer or a vane penetrometer.

7. The in-situ soil parameter measuring device based on pressure penetration according to claim 1, wherein the diameter of the working cylinder is not less than 5 times the diameter of the penetrometer.

8. The in-situ soil parameter measuring device based on pressure penetration according to claim 1, wherein the bottom of the working cylinder is provided with an insertion part, the insertion part is in the shape of an inverted truncated cone, and the end of the insertion part with a larger diameter is connected to the working cylinder.