High-fidelity sampling method for keeping oxidation-reduction state of soil in-situ stratum

Abstract

The invention provides a high-fidelity sampling method for keeping an oxidation-reduction state of a soil in-situ stratum, which comprises the following steps: step 10, drilling to a depth position of an underground water burial depth, and forming a preformed hole above the water level of the underground water; 20, the protective sleeve is installed in the preformed hole, and inert gas is introduced into the protective sleeve till an inner cavity of the protective sleeve is filled with the inert gas; and step 30, a high-fidelity sampling drilling tool is adopted to penetrate through the protective sleeve to perform downward collection to obtain a soil sample within a preset depth range below the water level of the underground water. According to the high-fidelity sampling method for keeping the oxidation-reduction state of the soil in-situ stratum, high-fidelity collection of soil samples below the water level of underground water can be achieved, and the oxidation-reduction potential of the soil in-situ stratum is kept.

Description

Technical Field

[0001] The invention belongs to the technical field of pollution control and treatment, and in particular relates to a high-fidelity sampling method for maintaining the redox state of an in-situ soil stratum. Background Art

[0002] Obtaining soil samples with the same redox potential as the in-situ strata is the basis for the whole life cycle management of contaminated sites, including investigation, control, remediation, and safe utilization. However, traditional static pressure, vibration, and rotary sampling drills cause large disturbances during the sampling process, and the samples will quickly come into contact with oxygen in the atmosphere during the collection process or after being taken out of the sampling drill. This will cause the organic carbon, divalent iron, and divalent manganese components in the soil to be oxidized, thereby changing the redox state of the soil and causing the redox potential of the collected samples to differ from that of the in-situ strata. Changes in the redox potential of the soil will affect the metabolic process of microorganisms, thereby changing the structure of the biological community in the soil and groundwater, and affecting the transformation of heavy metals and organic matter. On the other hand, certain components in the soil will undergo chemical reactions under the oxidation of oxygen in the air, changing the chemical form of clay minerals on the surface of soil particles, thereby affecting the migration process of heavy metals and organic matter in the soil and groundwater. At present, there is still a lack of sampling methods that can effectively maintain the redox potential of soil in the saturated zone below the groundwater level, making it difficult to obtain high-fidelity soil samples that are consistent with the redox potential of the in-situ strata. This has largely hindered the efficient implementation of contaminated site remediation work. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a high-fidelity sampling method for maintaining the redox state of the in-situ soil strata, which can achieve high-fidelity collection of soil samples below the groundwater level and maintain the redox potential of the in-situ soil strata.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: The present invention provides a high-fidelity sampling method for maintaining the redox state of an in-situ soil stratum, comprising the following steps: Step 10, drilling to the groundwater depth, forming a pre-formed hole above the groundwater level; Step 20, installing the protective sleeve into the pre-formed hole, and introducing an inert gas from the inlet of the fourth gas transmission channel of the protective sleeve until the volume of the introduced inert gas is 2 to 4 times the volume of the inner cavity of the protective sleeve; Step 30, using a high-fidelity sampling drill, installing a first drill rod at the top of the drilling body, and inserting the drilling body into the protective casing from the top of the protective casing; if the bottom end of the drilling body reaches the groundwater burial depth and the bottom end of the first drill rod is near the ground, then execute step 40; otherwise, execute step 50; Step 40 specifically includes: Step 401, installing a propulsion body at the top end of the first drill rod, and separating the cover body of the propulsion body from the hollow tube body; inserting the first sampling tube from the top end of the hollow tube body, so that the first sampling tube is located in the inner cavity of the first drill rod; Step 402, introducing inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the introduced inert gas is 3 to 5 times the volume of the inner cavity of the first drill pipe; installing the cover of the propulsion body on the top of the hollow tube body; Step 403, the propulsion body is pushed down, the first drill rod moves downward, and the soil sample enters the first sampling tube. When the first drill rod is completely pressed into the formation, the first sampling tube is filled with the soil sample; Step 404, separate the propulsion body from the top of the first drill rod, take out the first sampling tube filled with soil sample, and obtain the first section of soil sample below the groundwater level; install the first second drill rod at the top of the first drill rod; n=1; Step 405, install a propulsion body at the top of the nth second drill rod, and separate the cover of the propulsion body from the hollow tube body; install the n+1th sampling tube installed with n push rods from the top of the hollow tube body, so that the n+1th sampling tube is located in the inner cavity of the first drill rod; Step 406, introducing inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the introduced inert gas is 3 to 5 times the sum of the inner cavity volumes of the n second drill rods and the one first drill rod; installing the cover of the propulsion body on the top of the hollow tube body; Step 407, the propulsion body is pressed downward, the second drill rod and the first drill rod move downward, and the soil sample enters the n+1th sampling tube. When the nth second drill rod is completely pressed into the formation, the n+1th sampling tube is filled with soil samples; Step 408, separating the propulsion body from the top of the nth second drill rod, taking out the n+1th sampling tube filled with soil sample, and obtaining the n+1th section of soil sample below the groundwater level; Step 409, install the (n+1)th second drill rod on the top of the nth second drill rod; the value of n increases by 1; repeat steps 405 to 408 until the soil sample within the predetermined depth range is taken out; execute step 60; Step 50 specifically includes: Step 501, sequentially install the first, second, third, ..., and m+1 second drill rods on the top of the first drill rod until the bottom of the drilling body reaches the groundwater burial depth and the bottom of the m+1 second drill rod is near the ground; m is an integer greater than or equal to 0; p=1; Step 502, installing a propulsion body at the top of the m+pth second drill rod, and separating the cover of the propulsion body from the hollow tube body; inserting the pth sampling tube with the m+pth push rods installed thereon from the top of the hollow tube body, so that the pth sampling tube is located in the inner cavity of the first drill rod; Step 503, introducing inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the introduced inert gas is 3 to 5 times the sum of the inner cavity volumes of m+p second drill rods and one first drill rod; installing the cover of the propulsion body on the top of the hollow tube body; Step 504, the propulsion body is pushed down, and the m+p second drill rods and the first drill rod move downward, and the soil sample enters the pth sampling tube. When the m+pth second drill rods are all pressed into the formation, the pth sampling tube is filled with the soil sample; Step 505, separating the propulsion body from the top of the m+pth second drill rod, taking out the pth sampling tube filled with soil sample, and obtaining the pth section of soil sample below the groundwater level; Step 506, install the m+p+1th second drill rod on the top of the m+pth second drill rod, and the value of p increases by 1; repeat steps 502 to 505 until the soil sample within the predetermined depth range is taken out; execute step 60; Step 60, remove the high-fidelity sampling drill from the formation, remove the protective casing, and seal the pre-formed hole.

[0005] As a further improvement of the present invention, after the protective sleeve is installed, the top end of the protective sleeve is located above the ground, and the distance between it and the ground is 0.1 to 0.3 m; the bottom end of the protective sleeve is located below the groundwater level, and the distance between it and the groundwater level is 0.2 to 0.5 m.

[0006] As a further improvement of the present invention, the diameter of the protective sleeve is equal to the diameter of the pre-formed hole.

[0007] As a further improvement of the present invention, the diameter of the pre-formed hole is 5 to 10 times the diameter of the preset sampling soil core.

[0008] As a further improvement of the present invention, in step 10, a spiral drill rod is used to drill to form a pre-formed hole.

[0009] As a further improvement of the present invention, in step 10, a high-fidelity sampling drill is used to drill to form a pre-formed hole.

[0010] As a further improvement of the present invention, a high-fidelity sampling drill is used to drill and form a pre-formed hole, which specifically includes: Step 101, install the first drill rod at the top of the drilling body, install the first sampling tube into the first drill rod, and then install the propulsion body at the top of the first drill rod; press the propulsion body downward, the first drill rod moves downward, and the soil enters the first sampling tube. When the first drill rod is completely pressed into the formation, the first sampling tube is filled with soil; separate the propulsion body from the first drill rod, and take out the first sampling tube filled with soil; Step 102, install the first second drill rod at the top of the first drill rod, install the second sampling tube installed with a push rod into the first drill rod, and then install the propulsion body at the top of the first second drill rod; press the propulsion body downward, the first second drill rod moves downward, and the soil enters the second sampling tube. When the second second drill rod is completely pressed into the formation, the second sampling tube is filled with soil; separate the propulsion body from the first second drill rod, and take out the second sampling tube filled with soil; Step 103, install the second second drill rod on the top of the first second drill rod, install the third sampling tube installed with two push rods into the first drill rod, and then install the propulsion body on the top of the second second drill rod; press the propulsion body downward, the first second drill rod moves downward, and the soil enters the second sampling tube. When the second second drill rod is completely pressed into the formation, the second sampling tube is filled with soil; separate the propulsion body from the first second drill rod, and take out the second sampling tube filled with soil; Step 104, sequentially adding second drill rods, replacing a sampling tube each time a second drill rod is added, until the bottom end of the drilling body is located at the groundwater burial depth; Step 105, taking out the high-fidelity sampling drill from the formation to form a pre-drilled hole.

[0011] As a further improvement of the present invention, before the sampling tube is installed in the first drill rod, an inert gas is first introduced into the sampling tube until the sampling tube is filled with the inert gas.

[0012] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The high-fidelity sampling method for maintaining the redox state of the in-situ stratum of the soil provided by the present invention comprises the following steps: firstly drilling to the buried depth of the groundwater to form a pre-formed hole above the groundwater level; then installing a protective casing in the pre-formed hole, and introducing an inert gas into the protective casing; finally adopting a high-fidelity sampling drill to collect soil samples below the groundwater level; when sampling, the drilling body, the first drill rod, a plurality of second drill rods and the propulsion body are sequentially connected from bottom to top, the sampling tube filled with inert gas is installed in the first drill rod, and the inert gas is introduced from the inlet of the third gas transmission channel of the propulsion body, and the inert gas enters the sampling cavity through the third gas transmission channel of the propulsion body, the second gas transmission channel of the second drill rod and the first gas transmission channel of the first drill rod in turn, so that the sampling cavity is filled with inert gas, and the soil below the drilling body is isolated from the atmosphere; the drilling rig presses down the propulsion body to push the drilling body, The first drill rod and the second drill rod gradually move downward, and the soil sample enters the sampling tube. The soil sample entering the sampling tube never contacts the atmosphere. After the sampling tube is full, a new sampling tube is replaced, and inert gas is introduced again from the inlet of the third gas transmission channel of the propulsion body. The inert gas enters the sampling cavity through the third gas transmission channel of the propulsion body, the second gas transmission channel of the second drill rod, and the first gas transmission channel of the first drill rod in sequence, so that the sampling cavity is filled with inert gas, and the soil under the drilled body is isolated from the atmosphere. Then the pressure is pressed down for sampling, and the soil sample entering the sampling tube never contacts the atmosphere. By adding a second drill rod, the downward pressure depth is continuously increased to collect soil samples within a predetermined depth range. During the collection process, the soil under the drilled body is always effectively isolated from the atmosphere, and the redox potential of the soil in the saturated zone below the groundwater level is effectively maintained, thereby realizing high-fidelity collection of soil samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a stratum cross-sectional view after the protective casing is installed in the method of the embodiment of the present invention; Figure 2 is a cross-sectional view of a first drill rod in a method according to an embodiment of the present invention; Figure 3 is a top view of a first drill rod in a method according to an embodiment of the present invention; Figure 4 is a bottom view of the first drill rod in the method of the embodiment of the present invention; Figure 5 is a cross-sectional view of a second drill pipe in the method of an embodiment of the present invention; Figure 6 is a top view of a second drill rod in the method of an embodiment of the present invention; Figure 7 is a bottom view of the second drill pipe in the method of the embodiment of the present invention; Figure 8 is a cross-sectional view of a propulsion body in a method according to an embodiment of the present invention; Fig. 9is a top view of the hollow tube of the propulsion body in the method of the embodiment of the present invention; Fig.10 is a bottom view of the hollow tube of the propulsion body in the method of the embodiment of the present invention; Fig.11 It is a cross-sectional view of the drilling body in the method of the embodiment of the present invention.

[0014] In the figure: the first hollow rod body 110, the first gas transmission channel 111, the first gas guide groove 112, the second sealing ring 113, the first sealing ring 114, the first one-way valve 115, the second hollow rod body 120, the second gas transmission channel 121, the second gas guide groove 122, the third gas guide groove 123, the third sealing ring 124, the fourth sealing ring 125, the third gas transmission channel 21, the cover body 20, the hollow tube body 22, the fourth gas guide groove 23, the fifth sealing ring 24, the sixth sealing ring 25, the second one-way valve 26, the conical hollow drill bit 31, the seventh sealing ring 32, the protective sleeve 13, the fourth gas transmission channel 131, the groundwater level 3, and the ground 4. DETAILED DESCRIPTION

[0015] The technical solution of the present invention is described in detail below.

[0016] The embodiment of the present invention provides a high-fidelity sampling method for maintaining the redox state of the in-situ formation of soil, and adopts a high-fidelity sampling drill. The high-fidelity sampling drill includes a drilling body, a first drill rod, a second drill rod and a propulsion body, and the first drill rod, the second drill rod and the propulsion body all have inner cavities. The first drill rod is provided with a first gas transmission channel 111 connected to its inner cavity, the second drill rod is provided with a second gas transmission channel 121, and the propulsion body is provided with a third gas transmission channel 21. The high-fidelity sampling drill of the embodiment of the present invention also includes a sampling tube and a mandrel. When in use, the drilling body, a plurality of second drill rods, the first drill rod and the propulsion body are connected in sequence from bottom to top, and the inner cavities of the drilling body, the plurality of second drill rods, the first drill rod and the propulsion body are connected in sequence to form a sampling cavity, and the third gas transmission channel 21, the second gas transmission channel 121, the first gas transmission channel 111 and the sampling cavity are connected in sequence. The sampling tube is installed in the inner cavity of the first drill rod. Among them, the number of the second drill rod and the mandrel is determined according to the field collection depth. Preferably, the length of the sampling tube, the length of the first drill rod, the length of the second drill rod and the length of the mandrel are all equal, and the number of the second drill rods is equal to the number of the mandrels.

[0017] like Fig.11 As shown, the drilling body includes a conical hollow drill bit 31, the upper inner wall of the conical hollow drill bit 31 is provided with threads, the lower inner wall is provided with a circle of limiting protrusions, and the upper surface of the limiting protrusions is provided with a circle of seventh sealing rings 32.

[0018] like Figure 2As shown, the first drill rod includes a first hollow rod body 110, one end (bottom end) of the first hollow rod body 110 is provided with a first threaded boss for connecting with the drilling body, and the other end (top end) of the first hollow rod body is provided with a second threaded boss for connecting with the second drill rod. When in use, the first threaded boss is inserted into the conical hollow drill bit and is threadedly connected with the conical hollow drill bit, and the bottom end of the first threaded boss abuts against the limiting protrusion. The inlet of the first gas transmission channel 111 is located on the end surface of the second threaded boss, and the outlet is located on the inner wall surface of the first threaded boss. A first one-way valve 115 is provided at the outlet of the first gas transmission channel 111, which only allows the gas in the first gas transmission channel 111 to flow out, and does not allow the gas to enter the first gas transmission channel 111. It can effectively prevent soil gas containing pollutants in the formation from entering the first gas transmission channel 111. After entering, the polluted gas will be adsorbed on the surface of the first gas transmission channel 111 and pollute the first gas transmission channel 111.

[0019] Preferably, Figure 3 As shown, a half circle of first air guide groove 112 is provided on the end surface of the second threaded protrusion along the circumference of the inner cavity, and the first air guide groove 112 is connected to the inlet of the first air delivery channel.

[0020] Preferably, Figure 3 As shown, two circles of second sealing rings 113 are arranged on the end surface of the second threaded protrusion, and the inlet of the first gas transmission channel is located between the two circles of second sealing rings. Figure 4 As shown, a circle of first sealing ring 114 is provided on the end surface of the first threaded boss. After the first drill rod is connected to the drilling body, the first sealing ring 114 cooperates with the seventh sealing ring 32 to prevent groundwater from entering the cavity of the first drill rod through the connection between the first threaded boss and the drilling body, and at the same time, it can also prevent polluted gas dissolved in groundwater from entering the cavity of the drill rod and causing contamination of the inner wall of the drill rod.

[0021] As a preferred example, Figure 5 As shown, the second drill rod includes a second hollow rod body 120, one end (bottom end) of the second hollow rod body 120 is provided with a first thread groove for connecting with the first drill rod, and the first thread groove is matched with the second thread protrusion. The other end (top end) of the second hollow rod body 120 is provided with a third thread protrusion matched with the first thread groove, so that multiple second hollow rod bodies 120 can be connected in sequence. The inlet of the second gas transmission channel 121 is located on the end surface of the third thread protrusion, and the outlet is located on the bottom surface of the groove of the first thread groove.

[0022] Preferably, Figure 6 As shown, a half circle of second air guide groove 122 is provided on the end surface of the third threaded protrusion along the circumference of the inner cavity, and the second air guide groove 122 is connected to the inlet of the second air delivery channel. Figure 7As shown, a half circle of the third gas guide groove 123 is provided on the bottom surface of the groove of the first thread groove along the circumference of the inner cavity, and the third gas guide groove 123 is connected to the outlet of the second gas transmission channel. When the second drill rod is connected to the first drill rod, the first gas guide groove 112 is connected to the third gas guide groove 123 correspondingly, the first gas transmission channel 111 of the first drill rod is connected to the first gas guide groove 112, and the second gas transmission channel 121 of the second drill rod is connected to the third gas guide groove, so that even if the inlet of the first gas transmission channel of the first drill rod is not opposite to the outlet of the second gas transmission channel of the second drill rod, the first gas transmission channel and the second gas transmission channel can be connected, and the inert gas can be well transmitted. When two adjacent second drill rods are connected, the second gas guide groove 122 is connected to the third gas guide groove 123 correspondingly, the second gas transmission channel 121 on the upper second drill rod is connected to the third gas guide groove 123, and the second gas transmission channel 121 on the lower second drill rod is connected to the second gas guide groove. Therefore, even if the outlet and inlet of the second gas transmission channels of the two adjacent first drill rods are not opposite to each other, the second gas transmission channels of the two adjacent second drill rods can be connected, so that the inert gas can be well transmitted.

[0023] Preferably, Figure 6 As shown, two circles of third sealing rings 124 are arranged on the end surface of the third threaded protrusion, and the inlet of the second gas transmission channel is located between the two circles of third sealing rings 124. Figure 7 As shown, two circles of fourth sealing rings 125 are provided on the bottom surface of the first thread groove, and the outlet of the second gas transmission channel is located between the two circles of fourth sealing rings 125. After the first drill rod is connected to the second drill rod, the two circles of second sealing rings cooperate with the two circles of fourth sealing rings, and after two adjacent second drill rods are connected, the two circles of third sealing rings cooperate with the two circles of fourth sealing rings to prevent the inert gas from leaking at the threaded boss or the threaded groove connection, which causes a small inert gas flow rate at the gas outlet of the first drill rod or no gas is discharged, thereby failing to achieve the expected effect of removing all air in the drill rod cavity.

[0024] like Figure 8As shown, the propulsion body includes a cover body 20 and a hollow tube body 22. The end face of the cover body 20 is provided with a protrusion for inserting one end (top end) of the hollow tube body 22, and the other end (bottom end) of the hollow tube body 22 is provided with a second threaded groove for connecting to the second drill pipe, and the second threaded groove is adapted to the third threaded protrusion. The inlet of the third gas transmission channel 21 is located on the outer wall surface of the hollow tube body, and the outlet is located on the groove bottom surface of the second threaded groove. The cover body 20 and the hollow tube body 22 of the propulsion body are detachably connected, which is convenient for plugging and unplugging the cover body 20, ensuring the high-quality completion of the operation processes such as emptying the air in the drill pipe cavity and removing the sampling tube, and significantly improving the sampling efficiency. A second one-way valve 26 is provided at the inlet of the third gas transmission channel, which only allows exogenous gas to enter the third gas transmission channel 21, and does not allow the gas in the third gas transmission channel 21 to flow out. After the propulsion body, the second drill body and the first drill body are connected, the second one-way valve 26 is used in conjunction with the first one-way valve 115 to effectively prevent soil gas containing pollutants in the formation from entering the gas transmission channel, and prevent the polluted gas from being adsorbed on the surface of the gas transmission channel after entering, causing pollution to the gas transmission channel.

[0025] Preferably, Fig.10 As shown, a half circle of the fourth gas guide groove 23 is provided on the bottom surface of the second thread groove along the circumference of the inner cavity of the hollow tube body, and the fourth gas guide groove 23 is connected to the outlet of the third gas transmission channel. The propulsion body is connected to the second drill rod, the fourth gas guide groove 23 is correspondingly connected to the second gas guide groove 122, the third gas transmission channel 21 of the propulsion body is connected to the fourth gas guide groove 23, and the second gas transmission channel 121 of the second drill rod is connected to the second gas guide groove, so that even if the outlet of the third gas transmission channel is not opposite to the inlet of the second gas transmission channel, the third gas transmission channel and the second gas transmission channel can be connected, and the inert gas can be well transmitted.

[0026] During the sampling process, the two ends of the drill rod are more likely to stick to the contaminated soil, causing the gas guide groove to be blocked, and distilled water is needed to be used for cleaning on site. Therefore, in order to improve the sampling effect and ensure the complete connectivity of the gas transmission channel between the two adjacent drill rods, all gas guide grooves are set to half a circle.

[0027] Preferably, Fig. 9 As shown, a fifth sealing ring 24 is provided on the end surface of the hollow tube. After the cover 20 and the hollow tube 22 are connected, the fifth sealing ring can prevent the inert gas from leaking from the connection between the cover and the hollow tube, thereby reducing the flow of the inert gas entering the sampling cavity. Fig.10As shown, two circles of sixth sealing rings 25 are arranged on the bottom surface of the second thread groove, and the outlet of the third gas transmission channel is located between the two circles of sixth sealing rings 25. After the second drill pipe is connected to the propulsion body, the two circles of third sealing rings and the two circles of sixth sealing rings cooperate to prevent the inert gas from leaking at the threaded boss or the threaded groove connection, which causes a small inert gas flow rate at the gas outlet of the first drill pipe or no gas is discharged, thereby failing to achieve the expected effect of removing all the air in the drill pipe cavity.

[0028] The high-fidelity sampling drill tool in the embodiment of the present invention adopts two types of drill rods, namely the first drill rod and the second drill rod. The first drill rod is mainly used to fix and protect the sampling tube so that the sampling tube does not deform or damage during the sampling process. Therefore, the material requirements of the first drill rod are higher to ensure the strength and rigidity of the first drill rod. The conical hollow drill bit 31 is prone to deformation or damage during use. In order to facilitate quick replacement, the lower end of the first drill rod is set in the form of a threaded boss. The connection between the first drill rod and the drilling body is achieved by inserting the conical hollow drill bit. This can effectively avoid the situation where the conical hollow drill bit 31 cannot be removed after being damaged due to being embedded in the lower end of the first drill rod, thereby reducing the equipment maintenance cost during the sampling process. The second drill rod is mainly used to connect the first drill rod and the propulsion body. The load of the drilling rig power unit and the effect of the soil layer on it are significantly lower than those of the first drill rod. Therefore, its strength and rigidity requirements are lower than those of the first drill rod. In addition, the part of the second drill rod that is subjected to the greatest impact load is the top part connected to the propulsion body. Therefore, the top part of the second drill rod is designed to be in the form of a threaded protrusion. Compared with the use of a threaded groove, this can effectively avoid the situation where the propulsion body cannot be removed after being damaged because it is embedded in the top end of the second drill rod, thereby reducing the equipment maintenance cost during the sampling process.

[0029] The embodiment of the present invention provides a high-fidelity sampling method for maintaining the redox state of an in-situ soil formation, comprising the following steps: Step 10, drilling to the groundwater burial depth to form a pre-formed hole above the groundwater level.

[0030] Since there are various types of microorganisms in the soil near the depth of groundwater, including both aerobic and anaerobic microbial communities, the microbial community structure is complex. Before collecting soil samples below the groundwater level, pre-drilling holes above the groundwater level can avoid the compression of the strata within the depth range during the collection process of shallow unsaturated soil, causing changes in the soil pore structure, and further affecting the redox state of the collected soil samples.

[0031] Preferably, the diameter of the pre-formed hole is 5 to 10 times the diameter of the preset sampling soil core. By reasonably setting the diameter of the pre-formed hole, the compression effect of the soil collection process on the strata within the depth range can be effectively avoided, while reducing the stress release and deformation of the soil layer near the groundwater burial depth caused by the pre-formed hole excavation, and maintaining the original state of the in-situ strata. If the diameter of the pre-formed hole is too small, the stratum stress adjustment will be insufficient during the pre-formed hole process; if the diameter is too large, the sampling efficiency will be reduced.

[0032] There are many schemes for forming preformed holes. The first scheme is to use a spiral drill rod to drill and form a preformed hole.

[0033] The second option is to use high-fidelity sampling drill tools to drill and form pre-formed holes.

[0034] Specifically include: Step 101, install the first drill rod at the top of the drilling body, install the first sampling tube into the first drill rod, and then install the propulsion body at the top of the first drill rod; press the propulsion body, the first drill rod moves downward, and the soil enters the first sampling tube. When the first drill rod is completely pressed into the formation, the first sampling tube is filled with soil; separate the propulsion body from the first drill rod, and take out the first sampling tube filled with soil.

[0035] Step 102, install the first second drill rod on the top of the first drill rod, install the second sampling tube installed with a push rod into the first drill rod, and then install the propulsion body on the top of the first second drill rod; press the propulsion body downward, the first second drill rod moves downward, and the soil enters the second sampling tube. When the second second drill rod is completely pressed into the formation, the second sampling tube is filled with soil; separate the propulsion body from the first second drill rod, and take out the second sampling tube filled with soil.

[0036] Step 103, install the second second drill rod on the top of the first second drill rod, install the third sampling tube installed with two top rods into the first drill rod, and then install the propulsion body on the top of the second second drill rod; press the propulsion body downward, the first second drill rod moves downward, and the soil enters the second sampling tube. When the second second drill rod is completely pressed into the formation, the second sampling tube is filled with soil; separate the propulsion body from the first second drill rod, and take out the second sampling tube filled with soil.

[0037] Step 104, add second drill rods in sequence, replace a sampling tube each time a second drill rod is added, press the added second drill rod into the formation, take out the sampling tube filled with soil sample, until the bottom end of the drilling body is located at the groundwater burial depth.

[0038] Step 105, taking out the high-fidelity sampling drill from the formation to form a pre-drilled hole.

[0039] Step 20, such as Figure 1 As shown, the protective sleeve 13 is installed into the preformed hole. Figure 1 As shown, the protective sleeve 13 is provided with a fourth gas transmission channel 131, the inlet of the fourth gas transmission channel 131 is located on the top outer wall surface of the protective sleeve 13, and the outlet is located on the bottom inner wall surface. Bentonite slurry is filled between the outer side of the protective sleeve and the pre-formed hole to prevent the protective sleeve 13 from shaking in the soil layer and causing the air-locking effect to be weakened.

[0040] Preferably, the diameter of the protective sleeve 13 is equal to the theoretical construction diameter of the preformed hole.

[0041] Preferably, after installing the protective sleeve 13, Figure 1 As shown, the top of the protective sleeve 13 is located above the ground, and the distance between it and the ground 4 is 0.1 to 0.3 m. The top of the protective sleeve is higher than the ground, which can effectively prevent the soil around the sampling point from falling into the pre-formed hole and causing pollution to the soil of the in-situ formation. In addition, maintaining a distance between the top of the protective sleeve 13 and the ground 4 can provide sufficient operating space for the inlet design of the fourth gas transmission channel 131 and the subsequent introduction of inert gas.

[0042] The bottom end of the protective sleeve 13 is located below the groundwater level 3, and the distance between the protective sleeve 13 and the groundwater level is 0.2 to 0.5 m. The bottom end of the protective sleeve 13 is embedded a certain distance below the groundwater level, which can effectively avoid significant changes in the soil pore structure during the soil collection process near the groundwater burial depth, and maintain the redox state of the collected soil sample.

[0043] Inert gas is introduced from the inlet of the fourth gas delivery channel 131 of the protective sleeve 13 until the volume of the introduced inert gas is 2 to 4 times the volume of the inner cavity of the protective sleeve. The protective sleeve is filled with inert gas to prevent the soil near the groundwater burial depth from contacting the atmosphere and maintain the redox state of the soil near the groundwater burial depth.

[0044] Step 30, using a high-fidelity sampling drill, install a first drill rod at the top of the drilling body, and install the drilling body into the protective casing from the top of the protective casing. If the bottom of the drilling body reaches the groundwater burial depth and the bottom of the first drill rod is near the ground, then execute step 40. Otherwise, execute step 50.

[0045] Step 40 specifically includes: Step 401, install a propulsion body at the top of the first drill rod, and separate the cover of the propulsion body from the hollow tube body. Install the first sampling tube from the top of the hollow tube body, so that the first sampling tube is located in the inner cavity of the first drill rod.

[0046] Step 402: Introduce inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the inert gas introduced is 3 to 5 times the volume of the inner cavity of the first drill rod. Install the cover of the propulsion body on the top of the hollow tube.

[0047] Step 403, the propulsion body is pushed down, the first drill rod moves downward, and the soil sample enters the first sampling tube. When the first drill rod is completely pressed into the formation, the first sampling tube is filled with the soil sample.

[0048] Step 404, separate the propulsion body from the top of the first drill rod, take out the first sampling tube filled with soil sample, and obtain the first section of soil sample below the groundwater level. Install the first second drill rod at the top of the first drill rod. n=1.

[0049] Step 405: Install a propulsion body at the top of the nth second drill rod, and separate the cover of the propulsion body from the hollow tube body. Install the n+1th sampling tube installed with n push rods from the top of the hollow tube body, so that the n+1th sampling tube is located in the inner cavity of the first drill rod.

[0050] Step 406: Introduce inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the inert gas is 3 to 5 times the sum of the inner volumes of the n second drill rods and the first drill rod. Install the cover of the propulsion body on the top of the hollow tube.

[0051] Step 407, press down the propulsion body, the second drill rod and the first drill rod move downward, and the soil sample enters the n+1th sampling tube. When the nth second drill rod is completely pressed into the formation, the n+1th sampling tube is filled with soil samples.

[0052] Step 408, separate the propulsion body from the top of the nth second drill rod, take out the n+1th sampling tube filled with soil samples, and obtain the n+1th section of soil samples below the groundwater level.

[0053] Step 409: Install the (n+1)th second drill rod on the top of the nth second drill rod. The value of n is increased by 1. Steps 405 to 408 are repeated until the soil sample within the predetermined depth range is taken out. Step 60 is executed.

[0054] Step 50 specifically includes: Step 501, sequentially install the first, second, third, ..., and m+1 second drill rods on the top of the first drill rod until the bottom of the drilling body reaches the groundwater burial depth and the bottom of the m+1 second drill rod is near the ground. Wherein, m is an integer greater than or equal to 0. p=1.

[0055] Step 502: Install a propulsion body at the top of the m+pth second drill rod, and separate the cover of the propulsion body from the hollow tube body. Install the pth sampling tube with the m+pth top rod installed from the top of the hollow tube body, so that the pth sampling tube is located in the inner cavity of the first drill rod.

[0056] Step 503, inert gas is introduced from the inlet of the third gas delivery channel of the propulsion body until the volume of the introduced inert gas is 3 to 5 times the sum of the inner cavity volumes of m+p second drill rods and one first drill rod. The cover of the propulsion body is installed on the top of the hollow tube.

[0057] Step 504, press down the propulsion body, m+p second drill rods and the first drill rod move downward, and the soil sample enters the pth sampling tube. When the m+pth second drill rods are all pressed into the formation, the pth sampling tube is filled with soil samples.

[0058] Step 505, separate the propulsion body from the top of the m+pth second drill rod, take out the pth sampling tube filled with soil sample, and obtain the pth section of soil sample below the groundwater level.

[0059] Step 506: Install the m+p+1th second drill rod at the top of the m+pth second drill rod. The value of p increases by 1. Repeat steps 502 to 505 until the soil sample within the predetermined depth range is taken out. Execute step 60.

[0060] Step 60, remove the high-fidelity sampling drill from the formation, remove the protective casing (13), and seal the pre-formed hole.

[0061] The high-fidelity sampling method for maintaining the redox state of the in-situ strata of the soil provided by the present invention comprises the following steps: firstly drilling to the buried depth of groundwater to form a pre-formed hole above the groundwater level; then installing a protective casing in the pre-formed hole, and introducing an inert gas into the protective casing; finally adopting a high-fidelity sampling drill to collect soil samples below the groundwater level; when sampling, the drilling body, the first drill rod, N second drill rods and the propulsion body are sequentially connected from bottom to top, the sampling tube filled with inert gas is installed in the first drill rod, the inert gas is introduced from the inlet of the third gas transmission channel of the propulsion body, and the inert gas enters the sampling cavity through the third gas transmission channel of the propulsion body, the second gas transmission channel of the second drill rod and the first gas transmission channel of the first drill rod in turn, so that the sampling cavity is filled with inert gas, and the soil below the drilling body is isolated from the atmosphere; The main body is pushed forward by pressure, and the drilling main body, the first drill rod and the second drill rod are gradually moved downward, and the soil sample enters the sampling tube, and the soil sample entering the sampling tube is never in contact with the atmosphere; after the sampling tube is full, a new sampling tube is replaced, and inert gas is introduced from the inlet of the third gas transmission channel of the propulsion main body again, and the inert gas enters the sampling cavity through the third gas transmission channel of the propulsion main body, the second gas transmission channel of the second drill rod and the first gas transmission channel of the first drill rod in sequence, so that the sampling cavity is filled with inert gas, and the soil under the drilling main body is isolated from the atmosphere; the pressure is pressed down again for sampling, and the soil sample entering the sampling tube is never in contact with the atmosphere; by adding a second drill rod, the downward pressure depth is continuously increased, and soil samples within a predetermined depth range are collected, so as to effectively maintain the redox potential of the soil in the saturated zone below the groundwater level, and realize high-fidelity collection of soil samples.

[0062] The basic principles, main features and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above specific embodiments, and the descriptions in the above specific embodiments and the specification are only for further illustrating the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed for protection.

Claims

1. A high-fidelity sampling method for maintaining the redox state of soil in situ strata, characterized in that: The following steps are involved: Step 10, drilling to the groundwater depth, forming a pre-formed hole above the groundwater level; Step 20, installing the protective sleeve (13) into the pre-formed hole, and introducing an inert gas from the inlet of the fourth gas delivery channel (131) of the protective sleeve (13) until the volume of the introduced inert gas is 2 to 4 times the volume of the inner cavity of the protective sleeve; Step 30, using a high-fidelity sampling drill, installing a first drill rod at the top of the drilling body, and inserting the drilling body into the protective casing from the top of the protective casing; if the bottom end of the drilling body reaches the groundwater burial depth and the bottom end of the first drill rod is near the ground, then execute step 40; Otherwise, execute step 50; Step 40 Specific include: Step 401, installing a propulsion body at the top end of the first drill rod, and separating the cover body of the propulsion body from the hollow tube body; inserting the first sampling tube from the top end of the hollow tube body, so that the first sampling tube is located in the inner cavity of the first drill rod; Step 402, introducing inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the introduced inert gas is 3 to 5 times the volume of the inner cavity of the first drill pipe; installing the cover of the propulsion body on the top of the hollow tube body; Step 403, the propulsion body is pushed down, the first drill rod moves downward, and the soil sample enters the first sampling tube. When the first drill rod is completely pressed into the formation, the first sampling tube is filled with the soil sample; Step 404, separate the propulsion body from the top of the first drill rod, take out the first sampling tube filled with soil sample, and obtain the first section of soil sample below the groundwater level; install the first second drill rod at the top of the first drill rod; n=1; Step 405, install a propulsion body at the top of the nth second drill rod, and separate the cover of the propulsion body from the hollow tube body; install the n+1th sampling tube installed with n push rods from the top of the hollow tube body, so that the n+1th sampling tube is located in the inner cavity of the first drill rod; Step 406, introducing inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the introduced inert gas is 3 to 5 times the sum of the inner cavity volumes of the n second drill rods and the one first drill rod; installing the cover of the propulsion body on the top of the hollow tube body; Step 407, the propulsion body is pressed downward, the second drill rod and the first drill rod move downward, and the soil sample enters the n+1th sampling tube. When the nth second drill rod is completely pressed into the formation, the n+1th sampling tube is filled with soil samples; Step 408, separating the propulsion body from the top of the nth second drill rod, taking out the n+1th sampling tube filled with soil sample, and obtaining the n+1th section of soil sample below the groundwater level; Step 409, install the (n+1)th second drill rod on the top of the nth second drill rod; the value of n increases by 1; repeat steps 405 to 408 until the soil sample within the predetermined depth range is taken out; execute step 60; Step 50 specifically includes: Step 501, sequentially install the first, second, third, ..., and m+1 second drill rods on the top of the first drill rod until the bottom of the drilling body reaches the groundwater burial depth and the bottom of the m+1 second drill rod is near the ground; m is an integer greater than or equal to 0; p=1; Step 502, installing a propulsion body at the top of the m+pth second drill rod, and separating the cover of the propulsion body from the hollow tube body; inserting the pth sampling tube with the m+pth push rods installed thereon from the top of the hollow tube body, so that the pth sampling tube is located in the inner cavity of the first drill rod; Step 503, introducing inert gas from the inlet of the third gas delivery channel of the propulsion body until the volume of the introduced inert gas is 3 to 5 times the sum of the inner cavity volumes of m+p second drill rods and one first drill rod; installing the cover of the propulsion body on the top of the hollow tube body; Step 504, the propulsion body is pushed down, and the m+p second drill rods and the first drill rod move downward, and the soil sample enters the pth sampling tube. When the m+pth second drill rods are all pressed into the formation, the pth sampling tube is filled with the soil sample; Step 505, separating the propulsion body from the top of the m+pth second drill rod, taking out the pth sampling tube filled with soil sample, and obtaining the pth section of soil sample below the groundwater level; Step 506, install the m+p+1th second drill rod on the top of the m+pth second drill rod, and the value of p increases by 1; repeat steps 502 to 505 until the soil sample within the predetermined depth range is taken out; execute step 60; Step 60, remove the high-fidelity sampling drill from the formation, remove the protective casing (13), and seal the pre-formed hole.

2. The high-fidelity sampling method for maintaining the redox state of the soil in situ strata according to claim 1, characterized in that: After the protective sleeve (13) is installed, the top end of the protective sleeve (13) is located above the ground, and the distance between the top end and the ground is 0.1 to 0.3 m; the bottom end of the protective sleeve (13) is located below the groundwater level, and the distance between the bottom end and the groundwater level is 0.2 to 0.5 m.

3. The high-fidelity sampling method for maintaining the redox state of soil in situ strata according to claim 1, characterized in that: The diameter of the protective sleeve (13) is equal to the diameter of the preformed hole.

4. The high-fidelity sampling method for maintaining the redox state of soil in situ strata according to claim 1, characterized in that: The diameter of the pre-drilled hole is 5 to 10 times the diameter of the preset sampling soil core.

5. The high-fidelity sampling method for maintaining the redox state of soil in situ strata according to claim 1, characterized in that: In step 10, a spiral drill rod is used to drill to form a pre-formed hole.

6. The high-fidelity sampling method for maintaining the redox state of soil in situ strata according to claim 1, characterized in that: In the step 10, a high-fidelity sampling drill is used to drill and form a pre-formed hole.

7. The high-fidelity sampling method for maintaining the redox state of soil in situ strata according to claim 6, characterized in that: High-fidelity sampling drills are used to drill pre-drilled holes, including: Step 101, install the first drill rod at the top of the drilling body, install the first sampling tube into the first drill rod, and then install the propulsion body at the top of the first drill rod; press the propulsion body downward, the first drill rod moves downward, and the soil enters the first sampling tube. When the first drill rod is completely pressed into the formation, the first sampling tube is filled with soil; separate the propulsion body from the first drill rod, and take out the first sampling tube filled with soil; Step 102, install the first second drill rod at the top of the first drill rod, install the second sampling tube installed with a push rod into the first drill rod, and then install the propulsion body at the top of the first second drill rod; press the propulsion body downward, the first second drill rod moves downward, and the soil enters the second sampling tube. When the second second drill rod is completely pressed into the formation, the second sampling tube is filled with soil; separate the propulsion body from the first second drill rod, and take out the second sampling tube filled with soil; Step 103, install the second second drill rod on the top of the first second drill rod, install the third sampling tube installed with two push rods into the first drill rod, and then install the propulsion body on the top of the second second drill rod; press the propulsion body downward, the first second drill rod moves downward, and the soil enters the second sampling tube. When the second second drill rod is completely pressed into the formation, the second sampling tube is filled with soil; separate the propulsion body from the first second drill rod, and take out the second sampling tube filled with soil; Step 104, sequentially adding second drill rods, replacing a sampling tube each time a second drill rod is added, until the bottom end of the drilling body is located at the groundwater burial depth; Step 105, taking out the high-fidelity sampling drill from the formation to form a pre-drilled hole.

8. The high-fidelity sampling method for maintaining the redox state of soil in situ strata according to claim 1, characterized in that: Before the sampling tube is installed into the first drill pipe, an inert gas is first introduced into the sampling tube until the sampling tube is filled with the inert gas.

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