Device and method for directional solidification of sand by microbial induced calcium carbonate precipitation

Abstract

The present invention discloses a device and method for directional solidification of sandy soil by microbial induced calcium carbonate precipitation, comprising a drill rod, wherein a first air pipe, a second air pipe, a grouting pipe and a fixed pipe are sequentially arranged in the drill rod from the inside to the outside, a plurality of second telescopic pipes are also arranged on the circumferential outer wall of the drill rod, a plurality of first slurry outlet holes are also arranged on the outer wall of the second telescopic pipe, a first telescopic pipe is also arranged in the second telescopic pipe, an unlocking block is arranged at one end of the first telescopic pipe, a movable plate is also arranged in the fixed pipe, and the first air pipe is connected to the movable plate; a plurality of locking pieces are also arranged in the drill rod, and the locking pieces can fix the conical head on the circumferential outer wall of the drill rod. The present invention utilizes the second telescopic pipe to not only expand the microbial grouting solidification range, but also realize accurate directional solidification of any area of ​​the soil, thereby improving the solidification efficiency of the soil. After the microbial solidification of the soil is completed, the second telescopic pipe falls off from the drill rod to avoid loosening of the solidified soil.

Description

Technical Field

[0001] The invention relates to the technical field of rock mass engineering solidification and anti-seepage, and in particular to a device for directional solidification of sand soil by microbial-induced calcium carbonate precipitation. Background Art

[0002] Microbial induced calcium carbonate deposition (MICP) technology is a biologically induced mineralization reaction process. It uses the metabolism of high-yield urease alkaliphilic microorganisms (such as Bacillus pasteurianus) to form calcium carbonate precipitation in the environment, which plays a role in cementing sand and improving soil, and has broad prospects for engineering application. According to the current geotechnical engineering problems and the analysis of microbial induction technology, MICP technology can be used to solve the problems of foundation sand liquefaction, slope reinforcement, windbreak and sand consolidation. Compared with traditional chemical cementitious materials, this technology has the advantages of being environmentally friendly, highly controllable, and widely applicable. In recent years, it has attracted much attention from scholars at home and abroad. The development of MICP technology research has prompted many scholars to explore the curing conditions such as bacterial solution, nutrient solution, and culture environment through indoor and outdoor simulation experiments, and to test its curing effect through tests such as compressive strength and permeability, so as to continuously improve the curing technology, so that the technology can be widely used in solving rock and soil problems and realize the green revolution of traditional skills.

[0003] At present, when injecting microbial slurry into the soil for soil solidification and protection, most of the time, a grouting pipe is drilled into the soil to be solidified, and then a high-pressure pump is used to transport the microbial slurry into the soil through the slurry pipe. However, the diffusion distance of the microbial slurry in the existing grouting pipe is limited, resulting in a limited range of soil solidification. Therefore, it is necessary to frequently use the grouting pipe to drill different grouting holes for grouting, which makes the process complicated and the curing efficiency low, and it is impossible to achieve directional solidification of the soil. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art, and the purpose is to provide a device for directional solidification of sandy soil by microbial induced calcium carbonate precipitation. The second telescopic tube provided can expand the microbial grouting solidification range, improve the soil solidification efficiency, and realize directional solidification. At the same time, after the microbial solidification of the soil is completed, the second telescopic tube can be detached from the drill rod to avoid loosening of the solidified soil.

[0005] The present invention is achieved through the following technical solutions:

[0006] A device for directionally solidifying sand and soil by microbial induced calcium carbonate precipitation comprises a drill rod, wherein a coaxial first air pipe, a second air pipe, a grouting pipe and a fixing pipe are arranged inside the drill rod from inside to outside; a plurality of second telescopic pipes are arranged on the circumferential outer wall of the drill rod, a plurality of first slurry outlet holes are arranged on the outer wall of the second telescopic pipe, a conical head is arranged at one end of the second telescopic pipe, and the other end is detachably connected to the grouting pipe after sequentially inserting the outer wall of the drill rod and the fixing pipe along the radial direction of the drill rod, a first telescopic pipe is arranged inside the second telescopic pipe, a unlocking block is arranged at one end of the first telescopic pipe, and the other end is connected to the second air pipe, The fixed pipe is also provided with movable plates of the same number as the second telescopic tubes, and the movable plates are respectively located above each second telescopic tube, and are sequentially inserted into the second telescopic tube and the first telescopic tube, and the first air pipe is connected to the movable plates. When gas is introduced into the first air pipe, the movable plates can be retracted into the fixed pipe to separate the second telescopic tube from the grouting pipe; a plurality of locking parts are also provided in the drill rod, and the locking parts can fix the conical head on the circumferential outer wall of the drill rod, and when the gas introduced into the second air pipe enters the first telescopic tube, the unlocking block can unlock the locking parts.

[0007] In the technical solution, a first air pipe, a second air pipe, a grouting pipe and a fixed pipe are arranged in the existing drill rod, and the axes of the first air pipe, the second air pipe, the grouting pipe and the fixed pipe are kept in the same straight line, wherein the first air pipe and the second air pipe are respectively connected to an external high-pressure air pump, and the grouting pipe is connected to an external water pump filled with microbial slurry. In the initial state, under the action of the locking member on the drill rod, the first telescopic pipe and the second telescopic pipe are both restricted in the drill rod, and the conical head protrudes from the circumferential outer wall of the drill rod, and the drill rod is used to drill down the soil in the area to be solidified, and the drill rod is The drill pipe is sent into the soil to be solidified. When the drill rod reaches the specified solidification depth of the soil, a high-pressure gas is introduced into the second air pipe by using an external high-pressure air pump. The high-pressure gas enters the first telescopic tube through the second air pipe. Since the first telescopic tube and the second telescopic tube in the technical solution both adopt a corrugated tube structure made of polylactic acid, which has a certain retractable property, when the high-pressure gas enters the first telescopic tube, it can force the first telescopic tube to expand and stretch along the radial direction of the drill rod, so that the first telescopic tube moves along the radial direction of the drill rod. During the movement of the first telescopic tube, The locking piece can be unlocked so that the conical head can move on the drill pipe. As the high-pressure air pump from the outside continuously introduces high-pressure gas into the first telescopic tube, the first telescopic tube is forced to drive the second telescopic tube to move radially along the drill pipe. The conical head on the outer end of the second telescopic tube can force the second telescopic tube to extend horizontally in the soil to a certain length to reach the designated position to be solidified, thereby expanding the solidification range of the soil by the microbial slurry and realizing directional solidification. Since the second telescopic tube can move linearly in a certain direction in the sand, the second telescopic tube can move directionally in a certain direction in the sand, thereby realizing the effect of directional fixation of the sand. When the sand is solidified by microbial grouting, the second telescopic tube can be moved directionally to the solidification area by utilizing the characteristic that the second telescopic tube can move directionally, thereby ensuring that the microbial slurry in the second telescopic tube can flow directionally into the sand to be solidified, thereby avoiding the inability to control the flow direction of the microbial slurry during the grouting process of the sand, resulting in a part of the microbial slurry flowing into other areas, thereby reducing the accuracy of the sand solidification.During grouting, the microbial slurry is transported to the grouting pipe by an external water pump, and the microbial slurry enters the second telescopic pipe. Since the outer wall of the second telescopic pipe is provided with a plurality of first slurry outlet holes, which are distributed on the outer section of the second telescopic pipe, the microbial slurry entering the second telescopic pipe flows out through the first slurry outlet holes distributed on the second telescopic pipe, thereby injecting the microbial slurry into the soil to be solidified, and achieving the purpose of directional solidification of sandy soil. Since a plurality of second telescopic pipes are provided on the drill rod, the microbial slurry can be directional transported to soils of different depths during the drilling process of the drill rod. In addition, the principle that the gas passing into the first telescopic pipe is stretched in the horizontal direction is used to force the second telescopic pipe to extend a little length in the soil in the horizontal direction, thereby ensuring that the microbial slurry can be diffused to a larger range, so as to improve the solidification efficiency of the soil. ;

[0008] At the same time, when the second telescopic tube moves horizontally in the soil to expand the solidification range of the microbial slurry, since the second telescopic tube has a certain diameter, a cavity is formed in the process of the second telescopic tube moving in the soil. When the soil is solidified by grouting of the microbial slurry, the drill rod needs to be taken out of the soil. If the second telescopic tube is retracted into the drill rod, a cavity will be left in the soil after being retracted into the drill rod, causing the soil in the solidified area to loosen, affecting the solidification effect of the soil. For this reason, the second telescopic tube provided in the present technical solution adopts a corrugated tube structure made of polylactic acid, which can be degraded in the soil. For this reason, the present technical solution provides a movable plate on the fixed tube, and during the process of grouting the soil with microbial slurry, a movable plate is used. The movable plate can ensure that the end of the second telescopic tube is stably connected to the grouting tube, and the microbial slurry entering the grouting tube can flow into the soil through the second telescopic tube. When grouting is completed, high-pressure gas is introduced into the first air pipe by an external air pump to force the movable plate to retract into the fixed tube. At this time, the fixing effect of the movable plate on the second telescopic tube is released, and then high-pressure gas is continued to be introduced into the first telescopic tube to force the length of the first telescopic tube to continue to change, thereby pushing the second telescopic tube to continue to move away from the drill rod, ensuring that the end of the second telescopic tube is not in the drill rod. At this time, the second telescopic tube is separated from the drill rod, so that the drill rod will not drive the second telescopic tube to move back when it is recovered, thereby avoiding the soil collapse when the second telescopic tube moves back, thereby improving the solidification efficiency of the soil.

[0009] Furthermore, a first connecting tube matching the second telescopic tube is provided at the end of the second telescopic tube, and the first connecting tube is connected with the grouting tube after being inserted into the fixed tube; a second connecting tube is provided at the end of the first telescopic tube away from the unlocking block, and the second connecting tube is connected with the second air pipe; the movable plate is inserted into the first connecting tube and the second connecting tube in sequence.

[0010] The first connecting tube and the second connecting tube are both connected to the movable plate, so that the first connecting tube and the second connecting tube can be stably fixed in the drill rod; the first connecting tube is movably inserted into the grouting pipe. In order to ensure the air tightness of the connection between the first connecting tube and the grouting pipe, a sealing ring can be provided at the connection between the first connecting tube and the grouting pipe to ensure the movably connected first connecting tube and the grouting pipe, while avoiding leakage of microbial slurry during grouting.

[0011] Furthermore, the fixed tube is also provided with first grooves of the same number as the movable plate, and the first groove is provided with a first elastic member and a movable plate, one end of the first elastic member is connected to the inner bottom of the first groove, and the other end is connected to the movable plate, and a connecting rod is also provided on the movable plate, and the connecting rod is connected to the movable plate; a through hole is provided on the movable plate, one end of the through hole is connected to the first air pipe, and the other end is connected to the first groove, when gas is introduced into the first air pipe, the gas can push the movable plate to pull the movable plate into the first groove.

[0012] The movable plate is located in the second connecting cylinder, and a second groove is further provided on the end thereof, and the second groove is communicated with the through hole, a second elastic member and a connecting block are provided in the second groove, one end of the second elastic member is connected to the inner bottom of the second groove, and the other end is connected to the connecting block, a connecting hole is further provided on the side wall of the movable plate, and the connecting hole is communicated with the second groove, a first blind hole is further provided on the side wall of the connecting block, a third elastic member is provided in the first blind hole, a first limiting rod matching the connecting hole is provided on the third elastic member, and the first limiting rod is located in the connecting hole; a second blind hole is further provided on the inner wall of the first groove, and a fourth elastic member is provided in the second blind hole, the elastic force of the fourth elastic member is greater than the elastic force of the third elastic member, a second limiting rod matching the connecting hole is provided on the fourth elastic member, and the second limiting rod can extend into the connecting hole and push the first limiting rod into the first blind hole.

[0013] In order to ensure that the second telescopic tube can be quickly separated from the grouting tube in the drill pipe after the microbial slurry grouting and directionally solidifying the soil is completed, a first groove for placing the movable plate is set in the fixed tube. In the initial state, the elastic force generated by the first elastic member can push the movable plate to be inserted into the first connecting tube and the second connecting tube in sequence, thereby limiting the position of the first connecting tube on the second telescopic tube; when it is necessary to unlock and separate the second telescopic tube from the grouting tube, an external air pump is used to introduce gas into the first air pipe, and the gas enters the through hole on the movable plate, and then enters the first groove to act on the movable plate, forcing the first elastic member to be compressed, and under the action of the connecting rod, the movable plate is pulled back from the first connecting tube and the second connecting tube to the first groove of the fixed tube, thereby realizing the rapid separation between the second telescopic tube and the grouting tube.

[0014] When the second extension rod is in the engagement with the first extension rod, the second extension rod is in the engagement with the first extension rod, and the extension rod is in the engagement with the first extension rod.

[0015] Furthermore, a plurality of third blind holes are provided in the drill rod, and the locking piece includes a fifth elastic piece and a locking rod, the fifth elastic piece is located in the third blind hole, and the locking rod is connected to the fifth elastic piece. Limiting holes matching the locking rod are provided on both sides of the conical head, and the locking rod is located in the limiting holes. The interior of the conical head is a hollow structure, and two push rods are provided in the cavity of the conical head. The diameter of the push rod is smaller than the diameter of the locking rod, one end of the push rod is located in the limiting hole, and the other end contacts the outer wall of the unlocking block, and the diameter of the unlocking block gradually increases along the direction of the second telescopic tube.

[0016] In order to ensure that the conical head arranged on the outer wall of the drill rod is not pressed into the drill rod by the soil during the drilling process, thereby causing the soil to enter the drill rod, a third blind hole is also provided on the drill rod. The locking rod is inserted into the limiting hole of the conical head by means of the fifth elastic member arranged in the third blind hole, and the conical head is fixed by means of the locking rod. When the drilling work is completed and the second telescopic tube needs to be extended from the drill rod, gas is introduced into the second air pipe by means of an air pump, and the gas in the second air pipe enters into the first telescopic tube, forcing the first telescopic tube to stretch. In the process of the first telescopic tube moving in the horizontal direction, the unlocking block can push the push rod to push the unlocking rod to retract into the third blind hole, thereby realizing rapid unlocking, thereby ensuring that the first telescopic tube can continue to move in the horizontal direction.

[0017] Furthermore, the end of the conical head is also provided with a second slurry delivery hole connected to the interior.

[0018] In order to increase the diffusion range of the biological grouting liquid, a second slurry delivery hole is provided at the end of the conical head, so that part of the microbial slurry entering the second telescopic tube can flow out through the first slurry delivery hole, and the other part can flow out through the second slurry delivery hole, effectively increasing the solidification range of the microbial slurry.

[0019] Furthermore, a sixth elastic member is provided in the first telescopic tube, one end of the sixth elastic member is connected to the second connecting tube, and the other end of the sixth elastic member is connected to the unlocking block.

[0020] After the soil is solidified, since the second telescopic tube can be separated from the drill rod and then buried in the solidified soil, and the first telescopic tube does not directly contact the soil during the movement, it does not affect the soil solidification effect. However, the first telescopic tube needs to be recycled. Therefore, a sixth elastic member is also provided in the first telescopic tube. When the first telescopic tube is in a stretched state, the sixth elastic member is in a stretched state. After the high-pressure gas introduced into the first telescopic tube is discharged, the first telescopic tube can be quickly retracted into the drill rod under the action of the sixth elastic member, thereby realizing the recycling of the first telescopic tube.

[0021] The method for directional solidification of sand soil by microbial induced calcium carbonate precipitation comprises the following steps:

[0022] 1) Preparation of experimental sand samples: Screen the natural sand samples to obtain the sample gradation;

[0023] 2) Preparation of solidification solution: dissolve urea and calcium chloride solids in water to obtain solutions of a certain concentration;

[0024] 3) Place the experimental sand sample evenly and tightly into the container, moisten it with deionized water, and then drill the drill rod into the sand;

[0025] 4) When the drill pipe reaches the test depth, an external air pump is used to introduce gas into the second air pipe, and the gas enters the first telescopic tube, forcing the first telescopic tube to expand and move along the radial direction of the drill pipe. The unlocking block is used to unlock the conical head, so that the second telescopic tube can move in the horizontal direction and be inserted horizontally into the sand to be solidified;

[0026] 5) When the second telescopic pipe reaches the appropriate position, a certain amount of bacterial liquid and consolidation liquid are injected into the grouting pipe, and the microbial slurry is transported into the sand through the second telescopic pipe, and then cultured at a constant temperature;

[0027] 6) When the drill pipe needs to be removed, an external air pump is used to introduce gas into the first air pipe, and the gas enters the through hole of the movable plate, pushing the movable plate to move, so that the movable plate is moved out of the first connecting tube and the second connecting tube, thereby separating the second telescopic tube from the grouting pipe;

[0028] 7) Use the first telescopic tube to continue to push the second telescopic tube to move, ensuring that the tail end of the second telescopic tube moves to be flush with the outer wall of the drill pipe;

[0029] 8) Expel the gas introduced into the second air pipe, retract the first telescopic tube into the drill rod, and smoothly remove the drill rod from the sand.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] 1. The present invention can force the first telescopic tube to expand and stretch by introducing high-pressure gas into the second air pipe, thereby pushing the second telescopic tube to move radially along the drill pipe, effectively expanding the solidification range of the microbial slurry, and using the grouting pipe to introduce the microbial slurry into the second telescopic tube, so that the microbial slurry flows out through the first slurry delivery hole and the second slurry delivery hole on the second telescopic tube, thereby realizing accurate large-scale microbial grouting of the soil. In addition, the telescopic tubes on the device can be started at the same time, that is, large-scale microbial grouting is performed on soils of different depths at the same time, thereby improving the solidification efficiency of soils in large areas;

[0032] 2. The present invention uses a locking piece arranged on the drill rod to fix the conical head on the drill rod, thereby preventing soil from entering the drill rod during the drilling process. At the same time, when the second telescopic tube needs to move in the horizontal direction, the unlocking block can realize the rapid unlocking of the locking piece, thereby ensuring that the second telescopic tube can move in the horizontal direction rapidly.

[0033] 3. After the soil is solidified, the movable plate can be used to quickly separate the second telescopic tube from the grouting tube, thereby preventing the second telescopic tube from loosening the solidified soil during the recovery process, thereby improving the soil solidification effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0035] Figure 1 It is a schematic diagram of the structure of the present invention;

[0036] Figure 2 It is a structural schematic diagram of another state of the present invention;

[0037] Figure 3 It is a schematic structural diagram of the second telescopic tube of the present invention when it is separated from the drill rod;

[0038] Figure 4 For the present invention Figure 1 The structural diagram of the enlarged part A in the middle;

[0039] Figure 5 For the present invention Figure 1 The structural diagram of the enlarged part B in the middle;

[0040] Figure 6 For the present invention Figure 2 The schematic diagram of the structure after the enlargement of the middle C part;

[0041] Figure 7 is a schematic structural diagram of a first telescopic tube of the present invention;

[0042] Figure 8 It is a structural schematic diagram of the conical head of the present invention.

[0043] Marks and corresponding parts names in the attached drawings:

[0044] 1-drill pipe, 2-fixed pipe, 3-grouting pipe, 4-first air pipe, 5-second air pipe, 6-first telescopic pipe, 7-conical head, 8-second telescopic pipe, 9-first connecting tube, 10-unlocking block, 12-connecting rod, 13-movable plate, 14-through hole, 15-first elastic member, 16-second connecting tube, 17-movable plate, 18-push rod, 19-fifth elastic member, 20-locking rod, 21-first slurry outlet hole, 23-connecting block, 24-third elastic member, 25-first limiting rod, 26-second limiting rod, 27-fourth elastic member, 28-second elastic member, 29-sixth elastic member, 30-second slurry delivery hole. DETAILED DESCRIPTION

[0045] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary implementation modes of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0046] Example 1

[0047] like Figures 1 to 8As shown, the present invention includes a drill rod 1, wherein the drill rod 1 is provided with a first air pipe 4, a second air pipe 5, a grouting pipe 3 and a fixed pipe 2 in sequence from the inside to the outside, and the axes of the first air pipe 4, the second air pipe 5, the grouting pipe 3 and the fixed pipe 2 are in the same straight line; a plurality of second telescopic pipes 8 are further provided on the circumferential outer wall of the drill rod 1, and a plurality of first slurry outlet holes 21 are further provided on the outer wall of the second telescopic pipe 8, one end of the second telescopic pipe 8 is provided with a conical head 7, and the other end is detachably connected to the grouting pipe 3 after sequentially inserting the drill rod 1 and the fixed pipe 2 along the radial direction of the drill rod 1, and a first telescopic pipe 6 is further provided in the second telescopic pipe 8, one end of the first telescopic pipe 6 is provided with an unlocking block 10, and the other end is connected to the second air pipe 5 is connected, the fixed pipe 2 is further provided with movable plates 17 of the same number as the second telescopic pipes 8, the movable plates 17 are respectively located above each second telescopic pipe 8, and the movable plates 17 are sequentially inserted into the second telescopic pipe 8 and the first telescopic pipe 6, the first air pipe 4 is connected with the movable plates 17, when gas is introduced into the first air pipe 4, the movable plates 17 can be retracted into the fixed pipe 2, and the second telescopic pipe 8 is separated from the grouting pipe 3; the drill rod 1 is further provided with a plurality of locking members, the locking members can fix the conical head 7 on the circumferential outer wall of the drill rod 1, when the gas introduced into the second air pipe 5 enters the first telescopic pipe 6, the unlocking block 10 can unlock the locking members.

[0048] In the technical solution, a first air pipe 4, a second air pipe 5, a grouting pipe 3 and a fixed pipe 2 are arranged in the existing drill pipe 1. The axes of the first air pipe 4, the second air pipe 5, the grouting pipe 3 and the fixed pipe 2 are kept in the same straight line. The first air pipe 4 and the second air pipe 5 are respectively connected to the external high-pressure air pump, and the grouting pipe 3 is connected to the external water pump filled with microbial slurry. In the initial state, under the action of the locking member on the drill pipe 1, the first telescopic pipe 6 and the second telescopic pipe 8 are both restricted in the drill pipe 1, and the conical head 7 protrudes on the circumferential outer wall of the drill pipe 1, and the drill pipe is used to treat the solidification area. The drill is then drilled into the soil of the area, and the drill rod 1 is sent into the soil to be solidified. When the drill rod reaches the soil solidification depth, a high-pressure gas is introduced into the second air pipe 5 by using an external high-pressure air pump. The high-pressure gas enters the first telescopic tube 6 through the second air pipe 5. Since the first telescopic tube 6 and the second telescopic tube 8 in the technical solution are both made of a corrugated tube structure made of polylactic acid, which has a certain retractable property, when the high-pressure gas enters the first telescopic tube 6, it can force the first telescopic tube 6 to expand and stretch along the radial direction of the drill rod 1, so that the first telescopic tube 6 moves along the radial direction of the drill rod 1. , during the movement of the first telescopic tube 6, the locking piece can be unlocked, so that the conical head 7 can move on the drill pipe 1. As the external high-pressure pump continuously introduces high-pressure gas into the first telescopic tube 6, the first telescopic tube 6 is forced to drive the second telescopic tube 8 to move radially along the drill pipe 1. The conical head 7 on the outer end of the second telescopic tube 8 can force the second telescopic tube 8 to extend to a certain length in the soil in the horizontal direction, thereby expanding the solidification range of the soil by the microbial slurry. Since the second telescopic tube 8 can be moved linearly in a certain direction in the sand, the second telescopic tube 8 can be moved in a certain direction in the sand, thereby achieving the effect of directional fixation of the sand. When the sand is subjected to microbial grouting solidification, the second telescopic tube 8 can be moved in a directional manner, so that the second telescopic tube 8 can be moved in a directional manner to the area to be solidified, thereby ensuring that the microbial slurry in the second telescopic tube 8 can flow in a directional manner into the sand to be solidified, thereby avoiding the inability to control the flow direction of the microbial slurry during the grouting process of the sand, resulting in a part of the microbial slurry flowing into other areas, thereby reducing the accuracy of the sand solidification.During grouting, the microbial slurry is transported to the grouting pipe 3 by an external water pump, and the microbial slurry enters the second telescopic pipe 8. Since a plurality of first slurry outlet holes 21 are arranged on the outer wall of the second telescopic pipe 8, and the first slurry outlet holes 21 are distributed on the outer section of the second telescopic pipe 8, the microbial slurry entering the second telescopic pipe 8 flows out through the first slurry outlet holes 21 distributed on the second telescopic pipe 8, thereby injecting the microbial slurry into the soil to be solidified. Since a plurality of second telescopic pipes 8 are arranged on the drill rod 1, the microbial slurry can be transported to soils of different depths at the same time during the drilling of the drill rod 1. In addition, the microbial slurry can be transported to soils of different depths at the same time by using the first telescopic pipe 8. The principle of the gas passing into the contraction tube 6 to stretch in the horizontal direction forces the second telescopic tube to extend a certain length in the soil in the horizontal direction, thereby ensuring that the microbial slurry can diffuse to a larger range to improve the soil solidification efficiency; in addition, the microbial slurry in the technical solution flows out through the second telescopic tube 8 arranged on the drill rod 1. Since the second telescopic tube 8 can move linearly in a certain direction in the sand, the device can also meet the requirements of directional solidification of sand in actual use, that is, when the sand needs to be directional solidified, the direction of the stretching of the second telescopic tube 8 can be used to achieve accurate directional solidification of the sand. ;

[0049] At the same time, when the second telescopic tube 8 moves horizontally in the soil to expand the solidification range of the microbial slurry, since the second telescopic tube 8 has a certain diameter, a cavity is formed in the process of the second telescopic tube 8 moving in the soil. When the grouting of the microbial slurry is completed, the drill rod needs to be taken out of the soil. If the second telescopic tube 8 is retracted into the drill rod 1, the second telescopic tube 8 will leave a cavity in the soil after being retracted into the drill rod 1, causing the soil in the solidified area to loosen, thereby reducing the solidification effect of the soil. For this reason, the second telescopic tube 8 provided in the technical solution adopts a corrugated tube structure made of polylactic acid, which can be degraded in the soil. The technical solution provides a movable plate 17 on the fixed tube 2. During the process of grouting the microbial slurry into the soil, the movable plate 17 can be used to ensure that the second The end of the telescopic tube 8 is stably connected to the grouting tube 3, and the microbial slurry entering the grouting tube 3 can flow into the soil through the second telescopic tube 8. After the grouting is completed, high-pressure gas is introduced into the first air pipe 4 using an external air pump to force the movable plate 17 to retract into the fixed tube 2. At this time, the fixing effect of the movable plate 17 on the second telescopic tube 8 is released, and then high-pressure gas continues to be introduced into the first telescopic tube 6, forcing the length of the first telescopic tube 6 to continue to change, thereby pushing the second telescopic tube 8 to continue to move away from the drill rod 1, ensuring that the end of the second telescopic tube 8 is not in the drill rod 1. At this time, the second telescopic tube 8 is separated from the drill rod 1, so that the drill rod 1 will not drive the second telescopic tube 8 to move back when it is recovered, thereby avoiding the soil collapse when the second telescopic tube 8 moves back, thereby improving the soil solidification efficiency.

[0050] Example 2

[0051] On the basis of Example 1, a first connecting tube 9 matching the second telescopic tube 8 is further provided at the end of the second telescopic tube 8, and the first connecting tube 9 is connected with the grouting tube 3 after being inserted into the fixed tube 2; a second connecting tube 16 is further provided at the end of the first telescopic tube 6 away from the unlocking block 10, and the second connecting tube 16 is connected with the second air pipe 5; the movable plate 17 is inserted into the first connecting tube 9 and the second connecting tube 16 in sequence.

[0052] The first connecting tube 8 and the second connecting tube 16 are both connected to the movable plate 17, so that the first connecting tube 8 and the second connecting tube 16 can be stably fixed in the drill rod 1; the first connecting tube 9 is movably inserted into the grouting pipe 3. In order to improve the air tightness of the connection between the first connecting tube 9 and the grouting pipe 3, a sealing ring can be provided at the connection between the first connecting tube 9 and the grouting pipe 3 to ensure that the first connecting tube 9 is movably connected to the grouting pipe 3, while avoiding leakage of microbial slurry during grouting.

[0053] The fixed tube 2 is also provided with first grooves of the same number as the movable plate 17, and the first groove is provided with a first elastic member 15 and a movable plate 13, one end of the first elastic member 15 is connected to the inner bottom of the first groove, and the other end is connected to the movable plate 13, and the movable plate 13 is also provided with a connecting rod 12, and the connecting rod 12 is connected to the movable plate 17; the movable plate 17 is provided with a through hole 14, one end of the through hole 14 is connected to the first air pipe 4, and the other end is connected to the first groove, when gas is introduced into the first air pipe 4, the gas can push the movable plate 13 to pull the movable plate 17 into the first groove.

[0054] The movable plate 17 is located in the second connecting cylinder 16, and a second groove is further provided on the end thereof, the second groove is communicated with the through hole 14, a second elastic member 28 and a connecting block 23 are provided in the second groove, one end of the second elastic member 28 is connected to the inner bottom of the second groove, and the other end is connected to the connecting block 23, a connecting hole is further provided on the side wall of the movable plate 17, the connecting hole is communicated with the second groove, a first blind hole is further provided on the side wall of the connecting block 23, a third elastic member 24 is provided in the first blind hole, a first limiting rod 25 matching the connecting hole is provided on the third elastic member 24, and the first limiting rod 25 is located in the connecting hole;

[0055] A second blind hole is also provided on the inner wall of the first groove, and a fourth elastic member 27 is provided in the second blind hole. The elastic force of the fourth elastic member 27 is greater than the elastic force of the third elastic member 24. A second limiting rod 26 matching the connecting hole is provided on the fourth elastic member 27. The second limiting rod 26 can extend into the connecting hole and push the first limiting rod 25 into the first blind hole.

[0056] In order to ensure that the second telescopic tube 8 can be quickly separated from the grouting pipe 3 in the drill pipe 1 after the microbial slurry grouting is completed, a first groove for placing the movable plate 17 is set in the fixed tube 2. In the initial state, the elastic force generated by the first elastic member 15 can push the movable plate 17 to be inserted into the first connecting tube 8 and the second connecting tube 16 in sequence, thereby limiting the position of the first connecting tube 16 on the second telescopic tube 8; when it is necessary to unlock and separate the second telescopic tube 8 from the grouting pipe 3, an external air pump is used to introduce gas into the first air pipe 4, and the gas enters the through hole 14 on the movable plate 17, and then enters the first groove to act on the movable plate 13, forcing the first elastic member 15 to be compressed, and under the action of the connecting rod 12, the movable plate 17 is pulled from the first connecting tube 8 and the second connecting tube 16 to the first groove of the fixed tube 2, thereby realizing the rapid separation between the second telescopic tube 8 and the grouting pipe 3.

[0057] At the same time, in order to facilitate the second telescopic tube 8 to be able to smoothly detach from the drill pipe 1 without being interfered by the first air pipe 4, a connecting block 23 is also provided on the first air pipe 4. In the initial state, the elastic force generated by the third elastic member 24 pushes the first limiting rod 25 to extend into the connecting hole of the movable plate 17, and the high-pressure gas in the first air pipe 4 is used to push the movable plate 17 to retract into the first groove. When the connecting hole on the movable plate 17 moves to be flush with the second limiting rod 26, the elastic force of the fourth elastic member 27 is greater than the elastic force of the third elastic member 24, so that the second limiting rod 26 can The first limiting rod 25 is able to be pushed to compress the third elastic member 24 and retract from the connecting hole to the first blind hole of the connecting block 23. In order to ensure that the connecting block 23 can be smoothly separated from the movable plate 17, the maximum displacement of the first limiting rod 25 pushed by the second limiting rod 26 is that the end of the first limiting rod 25 is flush with the side wall of the connecting block 23. At this time, the connecting block 23 can be quickly separated from the movable plate 17 under the action of gravity, thereby successfully realizing the separation of the first air pipe 4 from the movable plate 17, and ensuring that the second telescopic tube 8 can be smoothly separated from the drill pipe 1.

[0058] Example 3

[0059] On the basis of Example 1, a plurality of third blind holes are further provided in the drill rod 1, and the locking member includes a fifth elastic member 19 and a locking rod 20. The fifth elastic member 19 is located in the third blind hole, and the locking rod 20 is connected to the fifth elastic member 19. Limiting holes matching the locking rod 20 are provided on both sides of the conical head 7, and the locking rod 20 is located in the limiting holes. The interior of the conical head 7 is a hollow structure, and two push rods 18 are further provided in the cavity of the conical head 7. The diameter of the push rod 18 is smaller than the diameter of the locking rod 20. One end of the push rod is located in the limiting hole, and the other end contacts the outer wall of the unlocking block 10. The diameter of the unlocking block 10 gradually increases toward the direction of the second telescopic tube 8.

[0060] In order to ensure that the conical head 7 arranged on the outer wall of the drill rod 1 is not pressed into the drill rod 1 by the soil during the drilling process, thereby preventing the soil from entering the drill rod 1, a third blind hole is also provided on the drill rod 1, and the locking rod 20 is inserted into the limiting hole of the conical head 7 by means of the fifth elastic member 19 arranged in the third blind hole, and the conical head 7 is fixed by means of the locking rod 20. When the drilling work is completed and the second telescopic tube 8 needs to be extended from the drill rod 1, gas is introduced into the second air pipe 5 by means of an air pump, and the gas in the second air pipe 5 enters into the first telescopic tube 6, forcing the first telescopic tube 6 to stretch. In the process of the first telescopic tube 6 moving in the horizontal direction, the unlocking block 10 can be used to push the push rod to push the unlocking rod 20 back into the third blind hole, thereby realizing rapid unlocking, thereby ensuring that the first telescopic tube 6 can continue to move in the horizontal direction.

[0061] Example 4

[0062] On the basis of Example 1, the end of the conical head 7 is further provided with a second slurry delivery hole 30 connected to the interior.

[0063] In order to increase the diffusion range of the biological grouting liquid, a second slurry delivery hole 30 is provided at the end of the conical head 7, so that a part of the microbial slurry entering the second telescopic tube 8 can flow out through the first slurry delivery hole, and the other part can flow out through the second slurry delivery hole 30, effectively increasing the solidification range of the microbial slurry.

[0064] Example 5

[0065] On the basis of Embodiment 2, a sixth elastic member 29 is further provided in the first telescopic tube 6 , one end of the sixth elastic member 29 is connected to the second connecting tube 16 , and the other end is connected to the unlocking block 10 .

[0066] After the soil is solidified, since the second telescopic tube 8 can be separated from the drill rod 1 and buried in the solidified soil, and the first telescopic tube 6 does not directly contact the soil during the movement, it does not affect the soil solidification effect. However, the first telescopic tube 6 needs to be recycled. Therefore, a sixth elastic member 29 is further provided in the first telescopic tube 6. When the first telescopic tube 6 is in a stretched state, the sixth elastic member 29 is in a stretched state. After the high-pressure gas introduced into the first telescopic tube 6 is discharged, the first telescopic tube 6 can be quickly retracted into the drill rod 1 under the action of the sixth elastic member 29, so that the first telescopic tube 6 can be recycled.

[0067] Example 6

[0068] The method for directional solidification of sand soil by microbial induced calcium carbonate precipitation comprises the following steps:

[0069] 1) Preparation of experimental sand samples: Screen the natural sand samples to obtain the sample gradation;

[0070] 2) Preparation of solidification solution: dissolve urea and calcium chloride solids in water to obtain solutions of a certain concentration;

[0071] 3) Place the experimental sand sample evenly and tightly into the container, moisten it with deionized water, and then drill the drill rod 1 into the sand;

[0072] 4) When the drill pipe 1 reaches the test depth, an external air pump is used to introduce gas into the second air pipe 5, and the gas enters the first telescopic tube 6, forcing the first telescopic tube 6 to expand and move along the radial direction of the drill pipe 1, and the unlocking block (10) is used to unlock the conical head 7, so that the second telescopic tube 8 can move in the horizontal direction, and the second telescopic tube (8) is inserted horizontally into the sand to be solidified;

[0073] 5) When the second telescopic pipe 8 reaches the appropriate position, a certain amount of bacterial liquid and consolidation liquid are injected into the grouting pipe 3, and the microbial slurry is discharged into the sand through the second telescopic pipe 8, and then cultured at a constant temperature;

[0074] 6) When the drill rod 1 needs to be removed, an external air pump is used to introduce gas into the first air pipe 4, and the gas enters the through hole 14 of the movable plate 17, pushing the movable plate 13 to move, so that the movable plate 17 is moved out of the first connecting tube 9 and the second connecting tube 16, thereby realizing the separation of the second telescopic tube 8 and the grouting tube 3;

[0075] 7) Using the first telescopic tube 6 to continue pushing the second telescopic tube 8 to move, ensuring that the end surface of the second telescopic tube 8 moves to be flush with the outer wall of the drill rod (1);

[0076] 8) Expel the gas introduced into the second air pipe 5, retract the first telescopic tube 6 into the drill rod 1, and smoothly remove the drill rod 1 from the sand.

[0077] The specific implementation methods described above have detailed descriptions of the objectives, technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are only specific implementation methods of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A device for directional solidification of sand by microbial induced calcium carbonate precipitation, comprising a drill rod (1), characterized in that: The drill rod (1) is provided with a coaxial first air pipe (4), a second air pipe (5), a grouting pipe (3) and a fixing pipe (2) from the inside to the outside; A plurality of second telescopic tubes (8) are also provided on the circumferential outer wall of the drill rod (1), and a plurality of first slurry outlet holes (21) are also provided on the outer wall of the second telescopic tube (8). A conical head (7) is provided at one end of the second telescopic tube (8), and the other end is inserted through the drill rod (1) and the fixed tube (2) in sequence along the radial direction of the drill rod (1) and then detachably connected to the grouting tube (3). A first telescopic tube (6) is also provided inside the second telescopic tube (8), and an unlocking block (10) is provided at one end of the first telescopic tube (6), and the other end is connected to the second air pipe (5). The fixed pipe (2) is also provided with movable plates (17) of the same number as the second telescopic pipes (8), the movable plates (17) are respectively located above each second telescopic pipe (8), and the movable plates (17) are sequentially inserted into the second telescopic pipe (8) and the first telescopic pipe (6), the first air pipe (4) is connected to the movable plates (17), and when gas is introduced into the first air pipe (4), the movable plates (17) can be retracted into the fixed pipe (2), so as to separate the second telescopic pipe (8) from the grouting pipe (3); The drill rod (1) is also provided with a plurality of locking members, which can fix the conical head (7) on the circumferential outer wall of the drill rod (1); when the gas introduced into the second air pipe (5) enters the first telescopic tube (6), the unlocking block (10) can unlock the locking members.

2. The device for directional solidification of sand by microbial induced calcium carbonate precipitation according to claim 1, characterized in that: A first connecting tube (9) matching the second telescopic tube (8) is also provided at the end of the second telescopic tube (8) located inside the drill rod (1); the first connecting tube (9) is inserted into the fixed tube (2) and communicated with the grouting tube (3); A second connecting tube (16) is also provided at the end of the first telescopic tube (6) away from the unlocking block (10), and the second connecting tube (16) is connected to the second air pipe (5); The movable plate (17) is inserted into the first connecting tube (9) and the second connecting tube (16) in sequence.

3. The device for directional solidification of sand by microbial induced calcium carbonate precipitation according to claim 2, characterized in that: The fixed tube (2) is also provided with first grooves of the same number as the movable plate (17), and the first groove is provided with a first elastic member (15) and a movable plate (13), one end of the first elastic member (15) is connected to the inner bottom of the first groove, and the other end is connected to the movable plate (13), and the movable plate (13) is also provided with a connecting rod (12), and the connecting rod (12) is connected to the movable plate (17); the movable plate (17) is provided with a through hole (14), one end of the through hole (14) is connected to the first air pipe (4), and the other end is connected to the first groove, and when gas is introduced into the first air pipe (4), the gas can push the movable plate (13) to pull the movable plate (17) into the first groove.

4. The device for directional solidification of sand by microbial induced calcium carbonate precipitation according to claim 3, characterized in that: A second groove is further provided on the end of the movable plate (17) located in the second connecting cylinder (16), the second groove is communicated with the through hole (14), a second elastic member (28) and a connecting block (23) are provided in the second groove, one end of the second elastic member (28) is connected to the inner bottom of the second groove, and the other end is connected to the connecting block (23), a connecting hole is further provided on the side wall of the movable plate (17), the connecting hole is communicated with the second groove, a first blind hole is further provided on the side wall of the connecting block (23), a third elastic member (24) is provided in the first blind hole, a first limiting rod (25) matching the connecting hole is provided on the third elastic member (24), and the first limiting rod (25) is located in the connecting hole; A second blind hole is also provided on the inner wall of the first groove, and a fourth elastic member (27) is provided on the second blind hole. The elastic force of the fourth elastic member (27) is greater than the elastic force of the third elastic member (24). A second limiting rod (26) matching the connecting hole is provided on the fourth elastic member (27). The second limiting rod (26) can extend into the connecting hole and push the first limiting rod (25) into the first blind hole.

5. The device for directional solidification of sand by microbial induced calcium carbonate precipitation according to claim 1, characterized in that: A plurality of third blind holes are also provided in the drill rod (1), and the locking member comprises a fifth elastic member (19) and a locking rod (20). The fifth elastic member (19) is located in the third blind hole, and the locking rod (20) is connected to the fifth elastic member (19). Limiting holes matching the locking rod (20) are provided on both sides of the conical head (7), and the locking rod (20) is located in the limiting holes. The interior of the conical head (7) is a hollow structure, and two push rods (18) are also provided in the cavity of the conical head (7). The diameter of the push rod (18) is smaller than the diameter of the locking rod (20). One end of the push rod is located in the limiting hole, and the other end contacts the outer wall of the unlocking block (10). The diameter of the unlocking block (10) gradually increases toward the direction of the second telescopic tube (8).

6. The device for directional solidification of sand by microbial induced calcium carbonate precipitation according to claim 1, characterized in that: The end of the conical head (7) is also provided with a second slurry delivery hole (30) communicating with the interior.

7. The device for directional solidification of sand by microbial induced calcium carbonate precipitation according to claim 2, characterized in that: A sixth elastic member (29) is also provided in the first telescopic tube (6), one end of the sixth elastic member (29) is connected to the second connecting tube (16), and the other end is connected to the unlocking block (10).

8. A solidification method based on the device for directional solidification of sand by microbial induced calcium carbonate precipitation according to claim 3 or 4, characterized in that: The following steps are involved: 1) Preparation of experimental sand samples: Screen the natural sand samples to obtain the sample gradation; 2) Preparation of solidification solution: dissolving urea and calcium chloride solids in water respectively to obtain a solution of a certain concentration; 3) The test sand sample is evenly and tightly packed into a container and moistened with deionized water, and then the drill rod (1) is drilled into the sand; 4) When the drill rod (1) reaches the test depth, an external air pump is used to introduce gas into the second air pipe (5), and the gas enters the first telescopic tube (6), forcing the first telescopic tube (6) to expand and move along the radial direction of the drill rod (1), and the cone head (7) is unlocked by the unlocking block (10), so that the second telescopic tube (8) can move in the horizontal direction, and the second telescopic tube (8) is inserted horizontally into the sand to be solidified; 5) When the second telescopic pipe (8) reaches the appropriate position, a certain amount of bacterial liquid and consolidation liquid is injected into the grouting pipe (3), and the microbial slurry is discharged through the second telescopic pipe (8) and transported into the sand, and then placed at a constant temperature for culture; 6) When the drill rod (1) needs to be removed, an external air pump is used to introduce gas into the first air pipe (4), and the gas enters the through hole (14) of the movable plate (17), pushing the movable plate (13) to move, so that the movable plate (17) is removed from the first connecting tube (9) and the second connecting tube (16), thereby realizing the separation of the second telescopic tube (8) and the grouting tube (3); 7) Using the first telescopic tube (6) to continue pushing the second telescopic tube (8) to move, ensuring that the end surface of the second telescopic tube (8) moves to be flush with the outer wall of the drill rod (1); 8) The gas introduced into the second air pipe (5) is discharged, the first telescopic tube (6) is retracted into the drill rod (1), and the drill rod (1) is smoothly removed from the sand.

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