Bio - Reinforcement Induced Evaluation Device and Method for Frozen Ground Foundation

Abstract

The present invention relates to a device and method for inducing and evaluating the bio - reinforcement of frozen soil foundations. Existing devices for microbial reinforcement of foundations are only used for experiments, and there is no suitable device capable of inducing the aggregation and reproduction of microorganisms. This device includes an induction tube, a sealing plug, a cross support, and a miniature vane shear apparatus; inside the induction tube is a liquid storage cavity, the sealing plug is inserted into the tube orifice at the top of the induction tube and is provided with a liquid injection hole; liquid seepage holes are evenly formed on the tube wall of the induction tube; at least one layer of cross support is arranged inside the induction tube, the cross support is of a hollow structure, side holes for inserting the cross support are arranged on the tube wall of the induction tube, and a miniature vane shear apparatus is arranged inside the hollow structure of the cross support, and the miniature vane shear apparatus extends out from the side holes for measurement. This device can induce the aggregation and reproduction of ice - nucleating microorganisms in frozen soil areas so as to achieve the purpose of reinforcing frozen soil foundations, can be used for the reinforcement of actual projects, fills the blank of the current device for supplying microbial stimulation nutrient solution, and can evaluate the effect after reinforcement.

Description

Technical Field

[0001] The present invention relates to the technical field of frozen soil foundation reinforcement, and particularly relates to a biological reinforcement frozen soil foundation induction evaluation device and method. Background Art

[0002] The degradation of the bearing capacity of foundations in cold regions has always been a hot and difficult issue in cold region engineering construction. The deterioration of the strength of the contact surface between the foundation and frozen soil caused by the melting of ice crystals in frozen soil is the essential reason for this problem. Especially in recent years, with the increase in temperature and frequent human engineering activities, the ice film on the contact surface that controls the bearing capacity of permafrost foundations has melted, the ice cementation strength has been lost, and the foundation has uneven settlement, posing a great threat to the safe operation of the upper engineering structures.

[0003] Currently, the "active cooling foundation" technology based on the principle of physical cooling is mainly used to cool frozen soil to ensure the consolidation state of the interface ice film, so as to achieve the bearing capacity stability of frozen soil foundations under climate change. The specific measures mainly include: heat pipes, ventilated pipe foundations, sunshade shed foundations, rubble foundations, and dry bridges, etc. However, the above measures have relatively high costs, low thermal efficiency, poor seasonal matching and human controllability, and with the global warming, the existing measures have shown insufficient to cope with the disasters caused by environmental changes. Microbial reinforcement of soil is a new method developed in recent years, which can significantly improve the strength, stiffness, permeability and liquefaction resistance of soil. Compared with the traditional common improvement processes, it has the characteristics of green environmental protection and environmental friendliness, and is more in line with the concept of sustainable development, and has broad application prospects in the field of soil reinforcement. But there are the following problems in the current application:

[0004] 1. Existing microbial reinforcement foundation devices (such as CN 111334419 A, CN 113063712 A, CN113389227A, etc.) are mostly used for indoor laboratory reinforcement, cannot be applied to actual engineering reinforcement, and there is a problem that the reinforcement effect cannot be feedback;

[0005] 2. Ice nucleation active bacteria or fungi widely distributed in frozen soil areas can cause unfrozen water in frozen soil to freeze at relatively high temperatures. However, due to their large randomness of distribution and lack of nutrients in the areas where they are located, it is difficult to form a scale, and there is currently no suitable device that can induce their aggregation and reproduction.

[0006] Therefore, in order to promote the application of microbial reinforcement of soil, it is urgent to develop new equipment and methods to overcome the problems that existing microbial reinforcement foundation devices are only used for experiments and there is no suitable device that can induce the aggregation and reproduction of microorganisms, and use this device in cold regions to induce the reproduction and aggregation of ice nucleating microorganisms with the characteristics of high-temperature ice formation, so as to ensure the stability of frozen soil and the contact surface between frozen soil and structures under temperature changes. Summary of the Invention

[0007] The object of the present invention is to provide a device and method for inducing and evaluating a bio-reinforced frozen soil foundation, so as to solve the problems that the existing devices for microbial reinforcement of foundations are only used for experiments and there is no suitable device capable of inducing the aggregation and reproduction of microorganisms.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A device for inducing and evaluating a bio-reinforced frozen soil foundation, the device comprising an induction tube, a sealing plug, a cross support and a miniature vane shear tester;

[0010] The interior of the induction tube is a liquid storage cavity, and the sealing plug is inserted into the pipe orifice at the top of the induction tube and is provided with a liquid injection hole;

[0011] Liquid seepage holes are uniformly formed in the pipe wall of the induction tube;

[0012] At least one layer of cross support is arranged inside the induction tube, the cross support is of a hollow structure, side holes for inserting the cross support are arranged on the pipe wall of the induction tube, and a miniature vane shear tester is arranged inside the hollow structure of the cross support, and the miniature vane shear tester extends out from the side holes for measurement.

[0013] Further, magnetic stirrers are arranged at the top of the cross support and at the bottom inside the induction tube.

[0014] Further, electric heating plates are arranged at the bottom and on the side of the cross support.

[0015] Further, a conical seat is arranged at the bottom of the induction tube.

[0016] Further, a pressure measuring hole and an air outlet hole are arranged on the sealing plug.

[0017] Further, the induction tube is of a double-layer pipe wall structure, and the double-layer pipe wall structure has a vacuum layer.

[0018] Further, the conical seat is of a hollow structure, and a storage battery is arranged inside the hollow structure. The storage battery is connected by wires to the miniature vane shear tester, the electric heating plate and the magnetic stirrer and supplies power to them.

[0019] Further, the device further comprises a temperature sensor and a moisture sensor;

[0020] Both the temperature sensor and the moisture sensor are arranged on the outer side of the pipe wall of the induction tube.

[0021] On the other hand, a method for using the device for inducing and evaluating a bio-reinforced frozen soil foundation as described above is provided, and the method comprises:

[0022] Using a pile press to vertically press the device into the soil on the side of the pile;

[0023] When the device is inserted into the soil by 1 / 2, extend the miniature vane shear apparatus, measure the resistance moment M1 before reinforcement, and use the temperature sensor to record the frozen soil temperature T1 at this time;

[0024] Retract the miniature vane shear apparatus, continue to press down the device to fully press the induction pipe into the soil;

[0025] Open the air outlet and the liquid injection hole, connect the external liquid addition pipe to the liquid injection hole, add nutrient solution to the liquid storage cavity of the device, and close the air outlet; Open the pressure measuring hole and connect an external pressure gauge, continue to add nutrient solution to the liquid storage cavity of the device, stop adding liquid, and close the liquid injection hole and the pressure measuring hole;

[0026] After the nutrient solution is released for a period of time, use the temperature sensor to measure the frozen soil temperature. When the frozen soil temperature reaches the same as T1, control the miniature vane shear apparatus to work and measure the resistance moment M2 after reinforcement;

[0027] Use the reinforcement value β to analyze the frozen soil strength before and after reinforcement:

[0028]

[0029] When the reinforcement value β reaches 50%, stop the supply of nutrient solution.

[0030] Furthermore, the method further includes:

[0031] While using the temperature sensor to record the frozen soil temperature T1 at this time, use the humidity sensor to record the frozen soil moisture content W1 at this time;

[0032] After stopping the supply of nutrient solution, continuously measure the frozen soil moisture content. When the frozen soil moisture content is greater than W1, continue to supply the nutrient solution.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The device of the present invention can induce the aggregation and reproduction of microorganisms in frozen soil areas to reinforce the frozen soil foundation, significantly improve the strength, stiffness and permeability of frozen soil, etc., and can be used for actual engineering reinforcement, filling the blank that there is only an indoor experimental device for the microbial stimulation nutrient solution supply device at present. Compared with the traditional commonly used improvement processes, it has the characteristics of green environmental protection and environmental friendliness, is more in line with the concept of sustainable development, and solves the problems of high cost, poor seasonal matching, large frozen soil disturbance, certain environmental pollution and poor human controllability of the existing frozen soil reinforcement technologies, improving social and economic benefits.

[0035] The device of the present invention can evaluate the effect after reinforcement, solving the problem that the existing reinforcement methods and reinforcement devices cannot achieve effect feedback. Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings of embodiments can also be obtained based on these drawings.

[0037] Figure 1 It is the external structure diagram of the device of the present invention.

[0038] Figure 2 It is the longitudinal sectional structure diagram of the device of the present invention.

[0039] Figure 3 It is the transverse sectional structure diagram of the device of the present invention without installing a magnetic stirrer.

[0040] Figure 4 It is the transverse sectional structure diagram of the device of the present invention with a magnetic stirrer installed.

[0041] The markings in the figure are:

[0042] 1 - induction pipe, 2 - cone seat, 3 - liquid seepage hole, 4 - side hole, 5 - sealing plug, 6 - liquid injection hole, 7 - pressure measuring hole, 8 - air outlet hole, 9 - vacuum layer, 10 - miniature vane shear tester, 11 - cross support, 12 - electric heating plate, 13 - magnetic stirrer, 14 - liquid storage cavity, 15 - storage battery. Detailed implementation manners

[0043] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively with reference to the relevant drawings. The preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0044] In the description of this patent, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this patent and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of this patent.

[0045] In the description of this patent, it should be noted that unless otherwise clearly specified and defined, terms such as "installation", "connection", "setting", etc. should be understood in a broad sense. For example, it can be fixedly connected and set, or detachably connected and set, or integrally connected and set. For those of ordinary skill in the art, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0046] The present invention provides a device for inducing and evaluating bio-cemented frozen soil foundation. Its working mechanism is to artificially add nutrient solution to the frozen soil to promote the aggregation and reproduction of ice nucleation bacteria in the frozen soil, increasing the number of ice nucleation bacteria, and then using the high-temperature ice-forming characteristics of ice nucleation bacteria to reinforce the frozen soil foundation. As Figure 1 shown, the device is generally cylindrical, including an induction tube 1, a cone base 2, a sealing plug 5, a cross support 11, and a miniature vane shear tester 10.

[0047] As Figure 1 and Figure 2 shown, the induction tube 1 is cylindrical with an open top. It has a liquid storage cavity 14 inside and is a double-wall tube structure. The double-wall tube structure has a vacuum layer 9, which has a structural temperature and heat preservation properties. The sealing plug 5 is inserted into the top nozzle of the induction tube 1 and is provided with a liquid injection hole 6, a pressure measurement hole 7, and an air outlet hole 8. The sealing plug 5 is a rubber plug with high sealing performance. The tube wall of the induction tube 1 is evenly provided with liquid seepage holes 3. Nutrient solution can be injected into the induction tube 1 through the liquid injection hole 6, and the nutrient solution can seep into the surrounding soil through the liquid seepage holes 3. The main function of the air outlet hole 8 is to discharge the excess gas inside. The pressure measurement hole 7 can be externally connected to a pressure gauge to measure the internal pressure of the induction tube 1 and ensure that there is a certain pressure inside the induction tube 1.

[0048] This device mainly induces the aggregation and reproduction of biological ice nucleation bacteria. The nutrient solution required by such microorganisms includes glycerol, glucose, citric acid, polyvinyl sorbitan fatty acid, and Tween 20, etc., which are nutrient solution components that can improve the activity of ice nucleation active bacteria.

[0049] At least one layer of cross support 11 is arranged inside the induction tube 1 to prevent the induction tube 1 from deforming. As Figure 1 and Figure 2 shown, two layers are arranged. As Figure 3 and 4 shown, the cross support 11 is a hollow structure and is also an important support component. The tube wall of the induction tube 1 is provided with side holes 4 for inserting the cross support 11. The miniature vane shear tester 10 is arranged inside the hollow structure of the cross support 11 and extends out from the side holes 4 for measurement. The miniature vane shear tester 10 can adopt the miniature vane shear tester (PS-VST-M) produced by Beijing Shuangjie Te Technology Co., Ltd., and its extension and retraction are controlled by its miniature hydraulic system.

[0050] As Figure 2, a magnetic stirrer 13 is provided at the top of the cross support 11 and the bottom inside the induction pipe 1 for stirring the nutrient solution in the liquid storage cavity 14. The magnetic stirrer 13 can be turned on and off according to the set time. The magnetic stirrer 13 is turned on once every 2 - 4 h and runs at a rotational speed maintained within the range of 1500 - 2000 rpm for 15 - 20 min to prevent the precipitation of the internal nutrient solution. An electric heating plate 12 is provided at the bottom and side of the cross support 11 for heating the nutrient solution in the liquid storage cavity 14 to prevent it from freezing at low temperatures. The electric heating plate 12 can be turned on and off according to the temperature of the internal nutrient solution. When the temperature of the nutrient solution is lower than 0.5 - 1 °C, the electric heating plate 12 is powered on and starts heating. When the temperature is higher than 2 °C, the power supply is disconnected and heating stops, ensuring that the temperature of the internal nutrient solution remains in a liquid state.

[0051] As Figure 2 , the conical seat 2 at the bottom of the induction pipe 1 is of a hollow structure, and a storage battery 15 is arranged inside the hollow structure. The storage battery 15 is connected by wires to the micro vane shear tester 10, the electric heating plate 12, and the magnetic stirrer 13 to supply power. For the wires, wire holes need to be added at the corresponding positions of the device.

[0052] The device further includes a temperature sensor and a moisture sensor. Both the temperature sensor and the moisture sensor are arranged on the outer side of the pipe wall of the induction pipe 1, and are arranged at the three - equal - height positions from top to bottom and embedded in the pipe wall. The temperature sensor can measure the surrounding temperature, and the moisture sensor can measure the surrounding moisture content.

[0053] The main material used for this device is steel, and the length of the induction pipe 1 can be customized within the range of 0.5 m - 2.5 m.

[0054] The usage method of the above - mentioned biological reinforcement frozen soil foundation induction evaluation device specifically includes the following steps:

[0055] S1: Use a pile press to vertically press the device into the soil on the side of the pile, including:

[0056] At a distance of 30 cm - 50 cm from the side of the pile, use a pile press to slowly vertically press the device into the soil. When 1 / 3 of the device has entered the soil, correct the verticality of the device to ensure that the vertical deviation in both the longitudinal and transverse directions does not exceed 0.5%.

[0057] S2: The first measurement, including:

[0058] Continue to start the pile press. When 1 / 2 of the device has entered the soil, extend the micro vane shear tester 10 to measure the pre - reinforcement resistance moment M1, and use the temperature sensor and the humidity sensor to record the frozen soil temperature T1 and the frozen soil moisture content W1 at this time.

[0059] S3: Withdraw the miniature vane shear apparatus 10, and continue to press down the device to fully press the induction pipe 1 into the soil mass. Stop pressing down when the closing plug 5 is 5 - 8 cm away from the ground surface.

[0060] S4: Inject nutrient solution, including:

[0061] Open the air vent 2 and the liquid injection hole 6. Connect the external liquid addition pipe to the liquid injection hole 6, add nutrient solution to the liquid storage cavity 14 of the device until it reaches 3 / 4 of the liquid storage cavity 14, and then close the air vent.

[0062] Open the pressure measurement hole 7 and connect an external pressure gauge. Continue to add nutrient solution to the liquid storage cavity 14 of the device until the pressure gauge shows more than 1.5 atmospheres. Then stop adding liquid and close the liquid injection hole 6 and the pressure measurement hole 7.

[0063] S5: After waiting for the nutrient solution to be released for 3 - 5 days, use the temperature sensor to measure the temperature of the frozen soil. When the temperature of the frozen soil reaches the same as T1, control the miniature vane shear apparatus 10 to work and measure the resistance moment M2 after reinforcement.

[0064] S6: Analyze the strength of the frozen soil before and after reinforcement using the reinforcement value β:

[0065]

[0066] When the reinforcement value β reaches 50%, stop supplying the nutrient solution. After stopping the supply of the nutrient solution, continuously measure the water content of the frozen soil. When the water content of the frozen soil is greater than W1, continue to supply the nutrient solution. This process can effectively regulate the supply of the nutrient solution, prevent soil eutrophication, and damage the ecological environment.

[0067] This device can use the miniature vane shear apparatus 10 to detect the biological reinforcement effect before and after guidance. By comparing the shear strength of the frozen soil before reinforcement and the shear strength of the frozen soil after reinforcement at the same temperature, analyze its reinforcement effect. The strength before and after reinforcement is calculated according to the vane shear strength calculation formula:

[0068]

[0069] Where:

[0070] Cu is the vane shear strength;

[0071] D is the diameter of the vane;

[0072] H is the height of the vane head;

[0073] M is the resistance moment.

[0074] There are a wide variety and a huge number of microorganisms in frozen soil. For example, there are hundreds of millions to tens of billions of bacteria, fungi, actinomycetes, algae, protozoa, etc. in 1 gram of soil. Therefore, the present invention proposes a device for strengthening frozen soil foundations, which induces the aggregation and reproduction of ice-nucleating microorganisms with the characteristic of forming ice at high temperatures widely distributed in cold regions, so that a certain concentration is reached in the strengthening area, and then ice embryos are generated at relatively high temperatures. With the migration of unfrozen water and the accumulation of ice nuclei, ice crystals in the frozen soil grow and extend continuously, thereby achieving the purpose of strengthening the frozen soil, solving the structural damage caused by the thaw settlement of frozen soil due to temperature rise, maximizing the utilization of frozen soil microbial resources, being not only environmentally friendly but also saving engineering maintenance costs, and solving engineering and environmental problems in production and life.

[0075] The device of the present invention can monitor various data in real time, effectively detect the strengthening effect, and can feedback the strengthening effect in real time.

[0076] Since the device seeps out nutrient solution into the frozen soil body, while strengthening the frozen soil foundation, different types of microorganisms can also be induced according to different nutrient solution formulas to achieve various functions such as nitrogen fixation and heavy metal treatment.

[0077] The above uses specific examples to elaborate on the present invention, which is only used to help understand the present invention and is not used to limit the present invention. For those skilled in the technical field to which the present invention belongs, based on the idea of the present invention, several simple deductions, deformations or substitutions can also be made.

Claims

1. Bioreinforcement-induced evaluation device for frozen soil foundation, characterized in that: The device includes an induction pipe (1), a sealing plug (5), a cross support (11) and a miniature vane shear apparatus (10); The inside of the induction pipe (1) is a liquid storage cavity (14), and the sealing plug (5) is inserted into the pipe orifice at the top of the induction pipe (1) and is provided with a liquid injection hole (6); Liquid seepage holes (3) are evenly arranged on the pipe wall of the induction pipe (1); At least one layer of cross support (11) is arranged inside the induction pipe (1), the cross support (11) is of a hollow structure, side holes (4) for inserting the cross support (11) are arranged on the pipe wall of the induction pipe (1), and a miniature vane shear apparatus (10) is arranged inside the hollow structure of the cross support (11), and the miniature vane shear apparatus (10) extends out from the side holes (4) for measurement; A pressure measuring hole (7) and an air outlet hole (8) are arranged on the sealing plug (5); The device further includes a temperature sensor and a moisture sensor; The temperature sensor and the moisture sensor are both arranged on the outer side of the pipe wall of the induction pipe (1).

2. The device according to claim 1, characterized in that: A magnetic stirrer (13) is arranged at the top of the cross support (11) and the bottom inside the induction pipe (1).

3. The device according to claim 2, characterized in that: Electric heating plates (12) are arranged at the bottom and the side of the cross support (11).

4. The device according to claim 3, characterized in that: A cone base (2) is arranged at the bottom of the induction pipe (1).

5. The device according to claim 4, characterized in that: The induction pipe (1) is of a double-layer pipe wall structure, and the double-layer pipe wall structure has a vacuum layer (9).

6. The device according to claim 5, characterized in that: The cone base (2) is of a hollow structure, and a storage battery (15) is arranged inside the hollow structure. The storage battery (15) is connected and supplies power to the miniature vane shear apparatus (10), the electric heating plates (12) and the magnetic stirrer (13) through wires.

7. Use method of the bioreinforcement-induced evaluation device for frozen soil foundation, characterized in that: The method includes: Vertically press the device into the soil by using a pile press on the side of the pile; When the device is inserted into the soil by 1 / 2, extend the miniature vane shear apparatus (10), measure the pre-reinforcement resistance moment M1, and record the frozen soil temperature T1 at this time by using the temperature sensor; Retract the miniature vane shear apparatus (10), continue to press down the device to press the induction pipe (1) completely into the soil; Open the air outlet hole (2) and the liquid injection hole (6), connect the liquid injection hole (6) to an external liquid addition pipe, add nutrient solution into the liquid storage cavity (14) of the device, and close the air outlet hole; open the pressure measuring hole (7) and connect it to an external pressure gauge, continue to add nutrient solution into the liquid storage cavity (14) of the device, stop adding liquid, and close the liquid injection hole (6) and the pressure measuring hole (7); After the nutrient solution is released for a period of time, measure the frozen soil temperature by using the temperature sensor. When the frozen soil temperature reaches the same as T1, control the miniature vane shear apparatus (10) to work and measure the post-reinforcement resistance moment M2; Analyze the strength of frozen soil before and after reinforcement using the reinforcement value β: When the reinforcement value β reaches 50%, stop the supply of nutrient solution; While using the temperature sensor to record the frozen soil temperature T1 at this time, use the humidity sensor to record the moisture content W1 of the frozen soil at this time; After stopping the supply of nutrient solution, continuously measure the moisture content of the frozen soil. When the moisture content of the frozen soil is greater than W1, continue to supply the nutrient solution.

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