A multi-layer sealed buried soil monitoring probe

Abstract

The application provides a multilayer sealing buried soil monitoring probe, belonging to the technical field of soil monitoring equipment, which comprises a main pipe body, a lower end cone head threadedly connected to the bottom end of the main pipe body, an upper end sealing assembly threadedly connected to the top end of the main pipe body, a plurality of groups of electrode installation through holes through the wall of the middle section of the main pipe body, a group of sensing electrodes arranged in each electrode installation through hole, a closed containing cavity formed in the main pipe body, a flexible sealing layer and a pouring layer layered filled in the closed containing cavity, and sealing rings arranged on the butt joint end faces of the lower end cone head, the main pipe body, the upper end sealing assembly and the main pipe body. The application adopts the above-mentioned multilayer sealing buried soil monitoring probe, solves the problems of single sealing layer level, temperature change and soil extrusion easily causing sealing cracking and leakage, weak protection of the electrode and cable parts, long-term buried ground easily causing circuit corrosion failure and short service life of the existing buried soil monitoring probe.

Description

Technical Field

[0001] This invention relates to the field of soil monitoring equipment technology, and in particular to a multi-layer sealed buried soil monitoring probe. Background Technology

[0002] Soil buried monitoring probes are permanently installed in farmland, saline-alkali land, slopes, and other outdoor soil layers. They rely on electrodes within the tube wall to collect parameters such as soil moisture and salinity at different depths, making them core equipment for soil moisture monitoring and soil and water environment observation. Currently, commercially available tubular soil probe sealing and protection solutions suffer from severe structural homogenization. The three weakest sealing areas—the shell, electrode penetration, and cable lead-out—use only a single-layer protective structure, typically a combination of a single rubber sealing ring and a single epoxy resin encapsulation. While this approach has low assembly and processing barriers, it only meets the basic waterproofing requirements for short-term shallow burial conditions and cannot adapt to long-term continuous buried monitoring scenarios. The existing sealing system structure is simplistic and lacks a tiered, progressive protection mechanism. Various sealing defects gradually become apparent over time, leading to a persistently high equipment failure rate.

[0003] The existing probe housing splicing points and cable outlets only have a single-seal structure. Due to long-term exposure to seasonal temperature variations, the plastic shell, metal electrodes, and potting compound have significantly different coefficients of thermal expansion and contraction, resulting in continuous micro-gaps at the sealing interface. Groundwater and soil saline ions can penetrate into the cavity through capillary action along these gaps. Simultaneously, soil settlement and lateral soil compression continuously pull on the cable and compress the housing joints, further exacerbating the cracking and debonding of the sealing layer. The cable root lacks a buffer structure, making it easy for the cable sheath to separate from the potting compound after external force, creating seepage channels. This frequently leads to internal solder joint corrosion, data drift, and even complete signal loss. While the outer shell may appear intact, the internal circuitry may fail, resulting in high costs for replacement and repair in the field.

[0004] The electrode penetration point on the tube wall of a tubular probe is the weakest point most prone to leakage. Existing products rely solely on potting compound to directly bond the electrode to the tube wall, lacking a mechanical compression sealing structure. Lateral forces from soil compression act entirely on the electrode-composite bonding surface, leading to long-term delamination of the compound layer and electrode outer wall, creating a water-permeable gap. Furthermore, a single-material potting compound cannot simultaneously compensate for deformation and isolate ions; rigid epoxy resin alone cannot counteract structural deformation caused by temperature changes, while the flexible compound layer lacks rigid isolation protection. The overall seal lacks layered redundancy design; damage to even one seal directly renders the entire unit unusable, resulting in a short buried lifespan. These shortcomings are even more pronounced in harsh soil environments with high humidity and high salinity, making it difficult to meet the requirements for long-term, stable, automated soil monitoring. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-layer sealed buried soil monitoring probe, which solves the problems of existing buried soil monitoring probes, such as single sealing layer, easy sealing cracking and leakage caused by temperature changes and soil compression, weak protection of electrode and cable parts, easy circuit corrosion failure after long-term burial, and short service life.

[0006] To achieve the above objectives, the present invention provides a multi-layer sealed buried soil monitoring probe, comprising a main body, a lower cone head threadedly connected to the bottom end of the main body, an upper sealing assembly threadedly connected to the top end of the main body, multiple sets of electrode mounting through holes being opened through the middle section of the main body, a set of sensing electrodes being installed in each set of electrode mounting through holes, a sealed accommodating cavity being formed inside the main body, and a flexible sealing layer and a potting layer being filled in layers inside the sealed accommodating cavity, and sealing rings being provided for the lower cone head, the mating end face of the main body, and the mating end face of the upper sealing assembly and the main body.

[0007] Preferably, the lower cone head has an internal threaded hole at the upper part, and two annular mounting grooves are opened vertically and parallel inside the internal threaded hole. Each annular mounting groove is equipped with a sealing ring. An annular step sealing surface is reserved at the top of the lower cone head, and a matching step surface is provided at the bottom of the main body. After tightening the lower cone head, the two sets of step surfaces clamp the two sealing rings to form a double-layer mechanical seal at the bottom.

[0008] Preferably, the sensing electrode is integrally formed with an outer contact section, a sealing boss, and an inner lead section. The outer diameter of the sealing boss is larger than the inner diameter of the electrode mounting through hole. An annular sealing gasket is sandwiched between the sealing boss and the inner wall of the main tube. The sealing gasket is synchronously attached to the inner wall of the main tube, the end face of the sealing boss, and the electrode rod. The flexible sealing layer is filled and covers the sealing gasket, the inner side of the sealing boss, and all the inner lead sections.

[0009] Preferably, the upper sealing assembly includes an end cap body, the end cap body having a through-type stepped cable perforation along the axial direction, the stepped cable perforation being divided from top to bottom into a large-diameter threaded gland section, a medium-diameter sealing cavity, and a small-diameter filling port, the small-diameter filling port being connected downward to the sealed receiving cavity of the main body, and the cable being led out through the stepped cable perforation from top to bottom.

[0010] Preferably, a sealing plug is installed inside the large-diameter threaded section, and a tightening nut is screwed into the upper external thread of the end cap body. The tightening nut presses the sealing plug downward to make the sealing plug radially hug the cable sheath to form the first mechanical seal of the cable. Silicone rubber is injected into the medium-diameter sealing cavity and cured to form a flexible filling layer. The flexible filling layer completely wraps the cable root sheath to form the second flexible seal of the cable.

[0011] Preferably, the filling area of ​​the potting layer is divided into the inner cavity of the small-diameter potting opening in the lower section of the end cap body and the lower part of the sealed accommodating cavity of the main body. The potting layer is separated into layers by the stepped shoulder and the flexible filling layer, and the side of the potting layer is smoothly connected to the flexible sealing layer.

[0012] Preferably, the potting layer covers the inner lead segment of the sensing electrode, the metal core wire of the cable extending into the tube, and the welding joint between the electrode and the cable. All metal conductive contacts inside the sealed cavity are embedded inside the potting layer.

[0013] Therefore, the present invention employs the above-mentioned multi-layer sealed buried soil monitoring probe, and the technical effects are as follows: 1. It adopts a three-level progressive layered sealing structure with simultaneous matching of the shell, electrodes and cables. The multi-layered seals provide redundant protection against each other, which can resist the sealing cracks and capillary water seepage caused by temperature difference deformation and soil compression. It significantly reduces the probability of corrosion of the probe's internal circuitry in saline-alkali and high-humidity environments, and effectively extends the service life of the probe buried in the field.

[0014] 2. The electrode through-wall is reinforced with a protrusion and a pressure washer-type mechanical seal, which is combined with a flexible adhesive seal for double protection. This disperses the lateral pressure of the soil, prevents the electrode from peeling off from the adhesive and allowing water to seep through, solves the industry pain point of frequent leakage at the electrode through-hole of the tubular probe, and improves the long-term stability of monitoring data.

[0015] 3. The cable lead-out end integrates a mechanical clamping gland, a flexible deformation compensation layer, and a hard potting isolation layer for three-stage sealing, which has the ability to resist pull-out, buffer deformation, and isolate ions, thus blocking the cable sheath from creeping channels. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of a multi-layer sealed buried soil monitoring probe according to the present invention; Figure 2 This is a partially enlarged cross-sectional view of the upper sealing assembly of the present invention; Figure 3 This is a partially enlarged cross-sectional view of the through-wall sealing of the sensing electrode of the present invention.

[0017] Figure Labels 1. Main body; 2. Lower cone head; 3. Sealing ring; 4. Sensing electrode; 41. Outer contact section; 42. Sealing boss; 43. Inner lead section; 5. Sealing gasket; 6. Flexible sealing layer; 7. End cap body; 8. Compression nut; 9. Sealing plug; 10. Flexible filling layer; 11. Potting layer; 12. Lead cable. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0020] Example 1 like Figures 1-3As shown, the present invention provides a multi-layer sealed buried soil monitoring probe, which is assembled sequentially with an upper sealing component, a main body 1, multiple sets of sensing electrodes 4 and a lower cone head 2. It is combined with multiple sealing rings 3 and a layered colloidal sealing structure to form a three-level progressive sealing system of "outer layer mechanical blocking, middle layer flexible deformation compensation, and inner layer hard isolation protection". The layered sealing protection structure is set simultaneously for the three major leakage high-incidence areas: the shell docking end face, the electrode through hole, and the cable lead-out stepped hole.

[0021] The main tube 1 serves as the overall support structure for the probe. It is a hollow, circular engineering plastic tube made of PVC or PC corrosion-resistant plastic, with a vertical, hollow cylindrical structure. The main tube 1 is divided into three functional sections: an upper docking area, a middle electrode mounting area, and a lower docking area. These three sections are integrally machined and cannot be separated. A continuous external thread is machined at the top of the outer wall of the main tube 1, forming the upper threaded docking section; a continuous external thread is machined at the bottom of the outer wall of the main tube 1, forming the lower threaded docking section. Multiple sets of through-holes for electrode mounting are equidistantly spaced along the vertical axis on the wall of the middle electrode mounting area of ​​the main tube 1. Each set of through-holes contains two parallel circular holes, and each set corresponds to a soil monitoring depth. This embodiment includes three sets of through-holes to accommodate monitoring of three soil layers: 10cm, 20cm, and 40cm. The hollow area inside the main body 1 forms a sealed cavity, which connects from top to bottom to the stepped hole inside the upper sealing component, the inner side of the middle electrode through hole, and the mating surface at the top of the lower cone 2. All the inner lead segments 43 of the electrodes, the metal core wires of the cables, and the layered sealing colloid are all housed inside this sealed cavity. The outer wall of the main body 1 can be frosted to increase the tightness of the fit with the surrounding soil after burial, ensuring that the outer contact segment 41 of the sensing electrode 4 is in full contact with the soil.

[0022] The external thread at the top of the main pipe body 1 engages with the internal thread at the bottom of the end cap body 7 of the upper sealing assembly. The external thread at the bottom of the main pipe body 1 engages with the internal thread hole pre-reserved on the upper part of the lower cone head 2. The main pipe body 1 is sandwiched between the lower cone head 2 and the end cap body 7, forming a three-section detachable main frame. Multiple sets of electrode mounting through holes in the wall of the main pipe body 1 serve as assembly channels. The sensing electrode 4 passes through the through holes from the sealed cavity inside the main pipe body 1, completing the positioning and installation of the electrode. The hollow cavity inside the main pipe body 1 serves as a space for colloid casting, where a flexible sealing layer 6 and a potting layer 11 are filled in layers. All sealing colloids are shaped and limited by the wall of the main pipe body 1 to prevent colloid outflow and misalignment. Annular stepped sealing surfaces are reserved at the threaded joints at both the upper and lower ends of the main pipe body 1. The stepped surfaces are used to press the sealing ring 3, forming an end-face mechanical seal limiting structure.

[0023] During the equipment assembly stage, the main pipe body 1 is first machined separately, and multiple sets of electrode mounting holes are pre-set on the pipe wall. External threads are machined at both ends. During assembly, the lower cone 2 is first screwed vertically from the bottom to the top of the main pipe body 1. After the threads are fully engaged, the top step surface of the lower cone 2 is pressed against the bottom step surface of the main pipe body 1, clamping two sealing rings 3 to achieve bottom end face sealing. Then, each set of sensing electrodes 4 is inserted from the inside of the main pipe body 1 to the outside to complete electrode positioning. Finally, the end cap body 7 is screwed down from the top of the main pipe body 1, and the bottom step surface of the end cap body 7 presses against the upper step surface of the main pipe body 1, clamping two sealing rings 3 to complete the top shell docking seal. After all external components are assembled, the flexible filling layer 10 and the potting layer 11 are poured downward from the central stepped hole of the end cap body 7. The colloid flows into the internal cavity of the main pipe body 1 and naturally fills the gaps around the electrodes, relying on the cylinder wall of the main pipe body 1 for shaping and curing. During the buried use phase, the main body 1's cylinder wall bears the radial extrusion force of the surrounding soil and the lateral shear force caused by soil settlement, evenly distributing the external soil load to the threaded connection parts at the upper and lower ends, avoiding local stress concentration that could compress the internal sealing colloid; the hollow cylinder wall of the main body 1 isolates large pieces of mud and sand from the outside, retaining only the electrode through holes as sensing contact channels, while the rest of the area is completely sealed, preventing large impurities from directly impacting the internal sealing structure; multiple sets of axially distributed electrode through holes ensure that the soil medium at different depths only contacts the corresponding electrode outer contact section 41, enabling independent acquisition of layered soil parameters, and preventing data from different soil layers from interfering with each other.

[0024] The main body 1 serves as the load-bearing base of the entire machine. The lower cone head 2 and the end cap body 7 are respectively connected by external threads at the upper and lower ends. Multiple sets of sensing electrodes 4 are positioned and installed through the through holes in the pipe wall. The internal hollow accommodating cavity is limited by layered sealing colloid. During assembly, the sealing rings 3 at both ends are tightened by the threads to form a mechanical seal for the shell base. Under buried working conditions, the soil compression load is evenly distributed. The layered through holes, together with the electrodes, enable simultaneous monitoring of soil at multiple depths. The cylinder wall isolates large pieces of mud and sand to protect the internal sealing structure. At the same time, the detachable threaded structure allows for individual replacement of parts, taking into account the convenience of processing, practicality of burial, and maintainability in the later stage.

[0025] The lower cone head 2 is located at the bottom of the main body 1 and serves as a composite component for guiding the machine into the soil and sealing the bottom end face. It is an integrally formed structure consisting of an upper cylindrical butt joint section and a lower cone tip soil entry section. The lower cone tip soil entry section has a tapered, conical structure with a rounded tip to reduce resistance when driven into the soil. An internally threaded through-hole is located at the center of the upper cylindrical butt joint section. Two annular sealing grooves are formed around the inner wall of the threaded through-hole, arranged parallel vertically. Each groove contains a separate sealing ring 3. The two sealing rings 3 are independent and do not fit together. A horizontal annular step sealing surface is pre-reserved at the top of the cylindrical section of the lower cone head 2. The diameter of the step surface is larger than the outer diameter of the main body 1's cylinder wall. After tightening, it can completely fit the bottom step surface of the main body 1, achieving synchronous compression and limiting of the two sealing rings 3. The sealing rings 3 are made of nitrile rubber and have an annular hollow structure. Under pressure, they can deform synchronously in the radial and axial directions to fill the mating gap.

[0026] The lower cone 2 connects to the main body 1 via its internal thread on the upper part, forming a threaded pair. During assembly, two sealing rings 3 are pre-placed in the two annular grooves inside the cone. The lower cone 2 is then tightened vertically upwards until the horizontal step surface at the top of the cone completely presses against the bottom step surface of the main body 1. The two sealing rings 3 are clamped between the two sets of step surfaces, simultaneously filling the thread engagement gap and the end face contact gap. The lower cone 2 is assembled at the very bottom of the main body 1 without any other intermediate transition parts, directly sealing the hollow opening at the bottom of the main body 1, forming a closed bottom end of the entire machine. The two sealing rings 3 are arranged in parallel and stacked, forming a double-layer redundant mechanical seal structure. The two sealing rings 3 bear pressure independently, and even if one sealing ring 3 ages and fails, the other can still maintain the end face sealing effect.

[0027] Two sealing rings 3 are sequentially embedded into the upper and lower annular mounting grooves inside the lower cone 2. After aligning the grooves, the lower cone 2 is tightened clockwise to align with the external thread at the bottom of the main pipe 1. During the continuous engagement of the threads, the stepped surface at the bottom of the main pipe 1 continuously presses down on the two sealing rings 3. The rubber sealing rings 3 undergo elastic deformation under axial compression. The outer radial expansion fills the thread gap between the external thread of the main pipe 1 and the internal thread of the cone, while the inner radial contraction fills the gap of the central through hole. The upper and lower sealing rings 3 respectively form two independent water-proof barriers. After tightening to the correct position, rotation is stopped. The self-locking force of the threads continuously maintains the pressure on the sealing rings 3, preventing loosening due to soil vibration or temperature changes. During the field installation phase, the upper end of the handheld probe is vertically aligned with the soil layer, and the lower end of the cone 2 is used to tap or press downwards. The cone tip breaks through the hard crust and loose soil layer, reducing the overall installation resistance and eliminating the need for pre-excavation of deep pits. Under long-term underground use, shallow underground silt and groundwater flow downwards along the outer wall of the main pipe 1. When they reach the bottom joint face, the first sealing ring 3 first blocks most of the groundwater and silt particles from penetrating. A small amount of water vapor that passes through the first sealing ring 3 is completely blocked by the second sealing ring 3. The double sealing structure blocks the capillary seepage channels at the bottom. The downward pull caused by soil settlement is entirely applied to the cone thread pair. The two sealing rings 3 buffer the gap changes caused by thread vibration, preventing the formation of seepage channels due to tiny gaps in the threads.

[0028] The lower cone 2 is connected to the lower end of the main body 1 via the upper internal thread and the lower end external thread. Two internal mounting grooves are fitted with independent sealing rings 3. After the threads are tightened, the bottom stepped surface of the main body 1 simultaneously presses against the double sealing rings 3 to form a double mechanical seal at the bottom. During installation, the cone tip breaks through the soil layer to reduce the burial resistance. Under long-term underground conditions, the double sealing rings 3 block the capillary infiltration of groundwater and sediment at the bottom in layers. The elasticity of the rubber compensates for the dimensional difference due to temperature changes. If one sealing ring 3 is damaged, the other can still continue to seal. At the same time, the threaded split structure allows for individual replacement of the cone, taking into account both the convenience of installation and the long-term reliability of the bottom seal.

[0029] Multiple sets of sensing electrodes 4 are assembled at the through-hole position of the middle section of the main body 1. Each set includes two parallel sensing electrodes 4. Each sensing electrode 4 is integrally formed from stainless steel and is divided into three continuous sections along the horizontal radial direction. From the outside to the inside, they are the outer contact section 41, the sealing boss 42, and the inner lead section 43. The outer contact section 41 extends out of the outer wall of the main body 1 and directly contacts the external soil medium to collect soil moisture and salinity parameters. The sealing boss 42 is a circular annular structure that protrudes radially outward in the middle of the electrode. The outer diameter of the disc is larger than the inner diameter of the electrode mounting through-hole in the main body 1, forming an axial pressing and limiting shoulder. The inner lead section 43 extends into the sealed accommodating cavity inside the main body 1, and the metal lead at the end is welded to the cable core wire for conduction.

[0030] An annular sealing gasket 5 is separately provided between the sealing boss 42 and the inner wall of the main body 1. The sealing gasket 5 is an independent rubber annular part, with its inner diameter fitting the electrode rod body and its outer diameter covering the entire edge of the through hole. The area around the electrode inside the main body 1 is filled with a flexible sealing layer 6. The flexible sealing layer 6 is made of silicone rubber flexible colloid, which completely wraps the inner end face of the sealing boss 42, the inner ring of the sealing gasket 5, the electrode rod body, and all the inner lead segments 43, filling all the tiny annular gaps inside the through hole. The inner side of the flexible sealing layer 6 is smoothly connected to the potting layer 11 and arranged in layers.

[0031] A single sensing electrode 4 is inserted from the sealed cavity inside the main body 1 into the electrode through hole in the pipe wall. During insertion, the disc structure of the sealing boss 42 gets stuck on one side of the inner wall of the main body 1 and cannot be completely inserted outward. An annular sealing gasket 5 is placed between the sealing boss 42 and the inner wall of the main body 1. The sealing gasket 5 simultaneously adheres to the inner wall of the main body 1, the inner end face of the sealing boss 42, and the outer wall of the electrode rod, forming an annular closed sealing surface. After all the sensing electrodes 4 are inserted and positioned, liquid silicone rubber is injected into the electrode area inside the main body 1. After curing, a flexible sealing layer 6 is formed. The flexible sealing layer 6 completely covers the inner side of the sealing boss 42, the edge of the sealing gasket 5, and all the inner lead segments 43, filling the annular gap inside the electrode through hole. The outer contact segment 41 of the electrode is exposed outside the main body 1 without any adhesive covering and directly contacts the soil medium. The single sensing electrode 4 is formed in three sections as one piece without segmented welding structure. Only the inner lead segment 43 at the end is welded to the cable core wire.

[0032] During the assembly stage, the electrodes are inserted from the inside out, relying on the central sealing boss 42 to form an axial limit, and simultaneously clamping the sealing gasket 5. After the upper and lower end components are locked by threads, the main body 1 cylinder wall has no axial displacement, and the sealing gasket 5 is continuously pressed. The gasket undergoes elastic deformation under compression, completely filling the annular gap between the electrode rod and the through hole in the tube wall, forming the first mechanical hard seal at the electrode root. Silicone rubber is injected and cured to form a flexible sealing layer 6, which serves as the second compensating seal to fill all the tiny capillary gaps that the gaskets cannot cover.

[0033] Under long-term buried conditions, the lateral compressive force generated by the surrounding soil acts directly on the outer contact section 41 of the electrode. The lateral thrust is transmitted along the electrode rod to the central sealing boss 42. The disc-shaped boss evenly distributes the lateral stress to the entire end face of the sealing gasket 5, avoiding local stress concentration that pulls on the colloid. When the temperature changes cyclically throughout the four seasons, there is a difference in the size of the plastic cylinder wall of the main body 1 and the stainless steel electrode due to thermal expansion and contraction. The two produce a small relative displacement. The flexible sealing layer 6, made of silicone rubber, has high elasticity and expands and contracts synchronously with the deformation of the components, preventing the colloid from cracking or peeling off from the electrode rod. If a small amount of underground saline water or soil moisture penetrates through the gaps in the outer wall and reaches the electrode through hole, the first sealing gasket 5 blocks most of the liquid penetration. The trace amount of water vapor is completely blocked by the flexible sealing layer 6 after passing through the gasket, and cannot penetrate inward along the electrode rod to contact the solder joint of the inner lead section 43, thus eliminating the common industry fault of water seepage and corrosion of the circuit at the electrode penetration point.

[0034] The upper sealing assembly is assembled on the top of the main body 1. The core load-bearing component is the end cap body 7, which is a stepped cylindrical integral structure. It is divided into a lower threaded mating section, a middle stepped sealing cavity, and an upper threaded clamping section along the vertical direction. The inner wall of the lower threaded mating section has internal threads for screwing with the upper external threads of the main body 1. The mating stepped surface holds two sealing rings 3 to form a mechanical seal at the top of the shell. A through-type stepped cable perforation is opened in the center of the end cap body 7 along the vertical axis. The perforation is divided into three cavities from top to bottom: the upper section is a large-diameter threaded gland section, the middle section is a medium-diameter sealing cavity, and the lower section is a small-diameter filling port. The three cavities are continuously connected, and the lower small-diameter filling port is directly connected to the sealed accommodating cavity inside the main body 1.

[0035] The upper large-diameter threaded section is fitted with a rubber sealing plug 9 inside, and a clamping nut 8 is fitted on the outside of the threaded section. The internal thread of the clamping nut 8 matches and screws into the external thread on the upper part of the end cap body 7. The middle section medium-diameter sealing cavity is filled with silicone rubber and cured to form a flexible filling layer 10. The lower small-diameter filling port is connected downward to the receiving cavity of the main body 1 for filling the filling layer 11. The lead cable 12 passes through the center hole of the clamping nut 8, the sealing plug 9, the flexible filling layer 10, and the small-diameter filling port from top to bottom. The metal core of the cable extends into the main body 1 and is welded to the inner lead section 43 of the electrode.

[0036] The end cap body 7 is connected to the upper external thread of the main body 1 by the bottom internal thread. Tightening the bottom stepped surface of the end cap presses the two sealing rings 3, completing the double-layer mechanical seal at the upper end of the housing. The sealing plug 9 is pre-inserted into the large-diameter threaded section of the upper part of the end cap body 7. The cable passes through the center through hole of the sealing plug 9 from top to bottom. The clamping nut 8 is inserted from the top of the cable and screwed into the upper external thread of the end cap body 7, pressing the sealing plug 9 downward.

[0037] After passing through the sealing plug 9, the cable extends into the middle section's medium-diameter sealing cavity. Silicone rubber is injected into the sealing cavity and cured to form a flexible filling layer 10, completely encasing the cable's root sheath. The cable continues downwards through the lower section's small-diameter sealing port, extending into the internal cavity of the main body 1. The small-diameter sealing port communicates with the cavity of the main body 1, where an integrally molded sealing layer 11 is injected. The flexible filling layer 10 and the sealing layer 11 are separated by a stepped shoulder, preventing them from mixing. The entire upper sealing assembly can be disassembled and reassembled solely through the threads between the end cap body 7 and the main body 1. The clamping nut 8 can be removed separately, facilitating future cable replacement and re-injection of sealing compound.

[0038] During the assembly stage, two sealing rings 3 are first placed on the upper stepped surface of the main body 1, aligned with the inner thread at the bottom of the end cap body 7, and tightened downwards. The two sealing rings 3 are deformed under pressure to fill the gap between the shells, forming a double-layer water barrier on the upper shell. After the cable passes through the sealing plug 9, it is inserted into the upper cavity of the end cap. The tightening nut 8 is tightened, and the nut presses down on the sealing plug 9. The rubber sealing plug 9 contracts radially inwards, tightly hugging the outer sheath of the cable, forming the first mechanical clamping seal of the cable, while also withstanding external tensile force. Then, liquid silicone rubber is injected into the middle section of the medium diameter sealing cavity. After curing, it forms a flexible filling layer 10, which completely wraps the outer sheath of the cable root and fills the tiny gap between the cable and the cavity wall, forming the second flexible compensation seal of the cable. Finally, epoxy resin is injected downwards through the small diameter potting port at the lower section of the stepped hole, which cures to form a potting layer 11, wrapping the internal metal core wire solder joints of the cable, forming the third hard isolation seal of the cable.

[0039] When used underground in the field, the tension generated by soil settlement and on-site cable pulling is entirely borne by the clamping nut 8 and the sealing plug 9, and the tension will not be directly transmitted to the internal cable welding points; the temperature difference between day and night causes the cable sheath and the plastic cavity of the end cap to change size, and the flexible filling layer 10 expands and contracts synchronously with its own elasticity, so that no separation gap will be generated at the cable root; a small amount of groundwater seeping down along the cable sheath will be blocked by the sealing plug 9 and the flexible filling layer 10 in turn, and the residual trace amount of water vapor will be completely isolated by the dense potting layer 11 after reaching the lower section, and will not be able to contact the internal metal welding points, thus preventing water seepage and short circuit faults at the cable root.

[0040] The potting layer 11 is a rigid epoxy resin colloid. The filling area is divided into two parts: the first part is the interior of the small-diameter potting cavity of the lower section of the end cap body 7, and the second part is the lower part of the completely sealed accommodating cavity inside the main body 1. The two cavities are connected and are integrally cured after the colloid is injected, without any splicing gaps. The potting layer 11 is separated from the flexible filling layer 10 by a stepped shoulder, and the outer side is smoothly connected to the flexible sealing layer 6 around the electrodes. It completely covers the inner lead segments 43 of all sensing electrodes 4, all metal core wires of the cables extending into the tube, and the welding joints between the electrodes and the cables. The filling height of the potting layer 11 covers the inner side of all electrode penetration positions and the welding joint area at the root of the cables. It is the innermost rigid isolation barrier of the entire sealing system. All metal conductive contacts are completely embedded inside the potting layer 11, with no exposed metal areas.

[0041] The potting layer 11 is filled using the small-diameter potting opening at the lower center of the end cap body 7. Liquid epoxy resin flows downwards along the stepped holes into the hollow cavity of the main body 1, naturally filling the space below the flexible sealing layer 6 around the electrode, completely covering all inner pin segments 43 and cable solder joints. After curing, the colloid adheres tightly to the upper flexible filling layer 10 and the flexible sealing layer 6 around the electrode. The three layers of sealing colloid are arranged continuously, with the outer mechanical seal, the middle flexible colloid, and the inner hard epoxy colloid forming a complete and unbroken sealing and protective chain. The potting layer 11 is completely confined by the cylinder wall of the main body 1 and the cavity of the end cap body 7. After curing, there is no risk of flow, delamination, or detachment. It is tightly bonded to all internal metal pins and solder joints without air gaps.

[0042] After all external components and layered flexible colloids are assembled and cured, liquid epoxy resin is poured downwards from the lower section of the stepped hole 7 on the upper end cover body. The liquid colloid fills all the empty spaces inside the main body 1 by gravity, covering all electrode pins and cable solder joints. After being left to cure completely, it forms a dense, high-hardness integrated potting layer 11. Under long-term buried conditions, if a small amount of water seepage occurs in the bottom double-layer sealing ring 3, the electrode double-layer seal, and the upper cable two-stage seal, a small amount of water vapor and salt ions will penetrate the outer and middle sealing structures, but will be completely blocked by the dense, impermeable epoxy resin potting layer 11, preventing them from contacting the internal conductive metal contacts. After curing, epoxy resin has high hardness and strong thermal stability, and is not affected by deformation and cracking caused by changes in soil temperature. It isolates the electrochemical corrosion of salt and alkali ions and avoids oxidation and open circuit of weld points. The potting layer 11 is tightly bonded to the flexible sealing layer 6 and the flexible filling layer 10, with no gaps between the colloids, and will not form hidden capillary water seepage channels, achieving full protection of all metal contacts inside the machine without exposure.

[0043] Therefore, this invention employs a multi-layer sealed buried soil monitoring probe, with the main pipe as the supporting base. A lower conical head with double sealing rings is threaded at the bottom to achieve a double-layer mechanical seal. Sensing electrodes with sealing bosses are installed through the pipe wall, forming a double-seepage-proof structure with sealing gaskets and a flexible sealing layer. The upper end of the main pipe is connected to an end cap body with a three-stage stepped cavity. A three-stage progressive seal for the cable is achieved through a tightening nut, sealing plug, flexible filling layer, and potting layer. An integrated epoxy resin potting layer serves as a bottom-layer isolation barrier. This constructs a three-level protection system: an outer mechanical seal, a middle flexible compensation layer, and an inner rigid isolation layer. Redundant layered seals are installed at the three major leakage weak points: shell joints, electrode through-holes, and cable exit points. This can offset the problems of seal cracking and capillary seepage caused by soil compression and seasonal temperature changes.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A multi-layer sealed buried soil monitoring probe, characterized in that, The system includes a main body with a lower cone head threaded to its bottom and an upper sealing assembly threaded to its top. Multiple electrode mounting holes are drilled through the middle section of the main body, with a set of sensing electrodes inserted into each hole. A sealed cavity is formed inside the main body, which is filled with a flexible sealing layer and a potting layer in layers. Sealing rings are provided at the lower cone head, the mating end face of the main body, and the mating end face of the upper sealing assembly and the main body.

2. The multi-layer sealed buried soil monitoring probe according to claim 1, characterized in that, The lower cone head has an internal threaded hole at the top, and two annular grooves are opened vertically and parallel inside the internal threaded hole. Each annular groove is equipped with a sealing ring. An annular step sealing surface is reserved at the top of the lower cone head, and a matching step surface is provided at the bottom of the main body. After tightening the lower cone head, the two sets of step surfaces face each other and clamp the two sealing rings to form a double-layer mechanical seal at the bottom.

3. The multi-layer sealed buried soil monitoring probe according to claim 1, characterized in that, The sensing electrode is integrally formed with an outer contact section, a sealing boss, and an inner lead section. The outer diameter of the sealing boss is larger than the inner diameter of the electrode mounting through hole. An annular sealing gasket is sandwiched between the sealing boss and the inner wall of the main tube. The sealing gasket is simultaneously attached to the inner wall of the main tube, the end face of the sealing boss, and the electrode rod. The flexible sealing layer is filled and covers the sealing gasket, the inner side of the sealing boss, and all the inner lead sections.

4. The multi-layer sealed buried soil monitoring probe according to claim 1, characterized in that, The upper sealing assembly includes an end cap body. The end cap body has a through-type stepped cable perforation along the axial direction. The stepped cable perforation is divided into a large diameter threaded gland section, a medium diameter sealing cavity, and a small diameter filling port from top to bottom. The small diameter filling port connects downward to the sealed accommodating cavity of the main body, and the cable is led out from top to bottom through the stepped cable perforation.

5. A multi-layer sealed buried soil monitoring probe according to claim 4, characterized in that, The large-diameter threaded section is equipped with a sealing plug inside. The upper external thread of the end cap body is matched with a tightening nut. The tightening nut presses the sealing plug downward so that the sealing plug radially hugs the cable sheath to form the first mechanical seal of the cable. The medium-diameter sealing cavity is filled with silicone rubber and cured to form a flexible filling layer. The flexible filling layer completely wraps the cable root sheath to form the second flexible seal of the cable.

6. A multi-layer sealed buried soil monitoring probe according to claim 4, characterized in that, The filling area of ​​the potting layer is divided into the inner cavity of the small-diameter potting opening in the lower section of the end cap body and the lower part of the sealed accommodating cavity of the main body. The potting layer is separated into layers by the stepped shoulder and the flexible filling layer, and the side of the potting layer is smoothly connected to the flexible sealing layer.

7. A multi-layer sealed buried soil monitoring probe according to claim 6, characterized in that, The potting layer covers the inner lead segment of the sensing electrode, the metal core wire of the cable extending into the tube, and the welding joint between the electrode and the cable. All metal conductive contacts inside the sealed cavity are embedded inside the potting layer.

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