Steel sheet pile structure and preparation and construction method thereof

Abstract

The invention provides a steel sheet pile structure and a preparation and construction method thereof.The steel sheet pile structure comprises a pile body, a protective shell, optical fibers, fiber cloth and a nose cone, the protective shell is arranged at one end of the pile body, and an opening is formed in one side of the protective shell; the optical fiber is laid on the pile body; the fiber cloth is adhered to the pile body and wraps the optical fiber; the nose cone is arranged at one end, facing the protective shell, of the optical fiber and is embedded in the protective shell. The protective shell is arranged on the pile body, and the nose cone is arranged at the end part of the optical fiber, so that the end part of the optical fiber can be embedded into the protective shell through the nose cone, and after the optical fiber is wrapped by the fiber cloth and is bonded with the pile body, the optical fiber is protected by the protective shell and the embedding effect of the nose cone and the protective shell, so that the optical fiber is not damaged during piling. Friction force is mainly borne by the protective shell and the fiber cloth, so that the optical fibers are prevented from being separated and damaged, and the reference stability is effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of steel sheet pile construction, and in particular to a steel sheet pile structure and a preparation and construction method thereof. Background Art

[0002] During the construction of steel sheet piles in foundation pits, when encountering hard plastic soil layers, steel sheet piles often cannot be driven directly, which makes it difficult for traditional construction methods to ensure the stability of the support structure and the construction quality. It is proposed to drill holes at the location of the steel sheet piles to remove the hard plastic soil and backfill with sand to solve this problem. However, due to the small diameter of the lead hole, the sand cannot be effectively compacted during the backfilling process, resulting in a low density and inability to constrain the steel sheet piles well. When the foundation pit is excavated, the steel sheet pile support structure may cause large deformation due to insufficient density of the sand, affecting construction safety.

[0003] The existing literature "China and Foreign Highways", Vol. 40, No. 3, June 2020, records a scheme based on the evolution law of the entire process of steel sheet pile construction using distributed optical fiber sensing technology. This paper proposes a new method for measuring the stress and deformation of steel sheet piles using optical fiber. Distributed sensing optical fiber is buried on the steel sheet piles, so that the sensing optical fiber and the steel sheet piles are integrated and deformed together. At this time, the steel sheet piles become components with the ability to sense deformation. It can monitor the strain, bending moment, deflection and other values ​​of the steel sheet piles to ensure the reliability and safety of cofferdam excavation. This method can analyze the changing law of the internal force and deformation of the support structure during drainage and excavation in the cofferdam, verify the effectiveness of the support structure, and can be used as a safety indicator in the cofferdam construction process.

[0004] As in the above scheme, the force on the steel sheet piles is analyzed through optical fibers, which is mainly used to detect the stability of the steel sheet piles. However, in this scheme, firstly, the specific layout structure of the optical fiber is not disclosed, so the specific protection structure of the steel sheet piles is unclear; secondly, it is not applied to the density detection of sand and soil. Therefore, during the construction process, the construction workers cannot clearly understand the density of the sand and soil, that is, the protective strength and stability of the steel sheet piles cannot be known, which may easily cause the problem of insufficient strength after the steel sheet piles are in place. Summary of the invention

[0005] In view of this, the present invention proposes a steel sheet pile structure with good optical fiber protection structure, which can obtain sand density and thus ensure construction safety, and its preparation and construction method, so as to solve the above-mentioned shortcomings in existing steel sheet pile construction.

[0006] The technical solution of the present invention is achieved in this way:

[0007] In one aspect, the present invention provides a steel sheet pile, comprising a pile body, a protective shell, an optical fiber, a fiber cloth and a head cone, wherein:

[0008] A protective shell is provided at one end of the pile body, and one side of the protective shell has an opening;

[0009] The optical fiber is laid on the pile;

[0010] The fiber cloth is bonded to the pile body and covers the optical fiber;

[0011] The head cone is arranged on one end of the optical fiber facing the protective shell and is embedded in the protective shell.

[0012] On the basis of the above technical solution, preferably, the protective shell includes a shell and a cone plate, wherein:

[0013] The shell is a semicircular shell structure, which is buckled on the pile body and has an opening;

[0014] The cone plate is arranged on a side of the shell body away from the nose cone.

[0015] On the basis of the above technical solution, preferably, the head cone includes a profiling section, a transition section and a bonding section, wherein:

[0016] The profiling section is arranged in the protective shell, the profiling section fits the inner wall of the protective shell and the pile body, and the profiling section extends to the outside of the protective shell;

[0017] The transition section is arranged on one end of the contour section located outside the protective shell;

[0018] The bonding section is arranged on one end of the transition section away from the contouring section, and the fiber cloth wraps the bonding section.

[0019] On the basis of the above technical solution, preferably, it further comprises a first screw, which is arranged on a surface of the pile body away from the head cone, and the first screw penetrates the pile body and is screwed together with the head cone through a thread.

[0020] On the basis of the above technical solution, preferably, the fiber cloth is in a strip structure, and the fiber cloth includes a first protruding portion, a second protruding portion and a holding portion, wherein:

[0021] The first protrusion is formed by wrapping the optical fiber with a fiber cloth;

[0022] The second protrusion is formed by wrapping the bonding section with fiber cloth;

[0023] The pressing portion is arranged on one side of the second protruding portion and is clamped by the pile body and the head cone.

[0024] On the basis of the above technical solution, preferably, it further comprises a second screw, and a T-shaped slot is provided on the fiber cloth, wherein:

[0025] A T-shaped groove is provided on the pressing portion to form two pressing sheets;

[0026] The pressing piece is clamped by the pile body and the head cone;

[0027] A threaded hole is provided on the portion of the profiling section extending to the outside of the protective shell, and a blind hole is provided on the pile body corresponding to the threaded hole;

[0028] The second screw is screwed into the threaded hole and pushes the pressing piece into the blind hole.

[0029] On the basis of the above technical solution, preferably, the optical fiber is arranged in a straight line or a winding shape on the pile body.

[0030] In another aspect, the present invention provides a method for preparing the above-mentioned steel sheet piles, comprising the following steps:

[0031] S1. Weld a protective shell on the pile body and integrate a head cone at the end of the optical fiber;

[0032] S2. Grind the pile body corresponding to the opening of the protective shell;

[0033] S3, applying adhesive on the polished surface of the pile body;

[0034] S4, setting one end of the fiber cloth on the pressing sheet, sleeve it on the optical fiber through the T-slot, and then lay it on the pile body;

[0035] S5, fitting the nose cone into the protective shell;

[0036] S6, passing the first screw through the pile body and screwing it with the head cone through a thread to clamp the end of the fiber cloth;

[0037] S7, connecting the second screw to the threaded hole of the head cone to partially push the pressing sheet into the blind hole of the pile body;

[0038] S8. Lay out the optical fiber first, then lay out the remaining fiber cloth, and roll the fiber cloth to make the fiber cloth firmly bonded by the adhesive.

[0039] In another aspect, the present invention provides a steel sheet pile construction method, using the above-mentioned steel sheet piles, which comprises the following steps:

[0040] S1. Excavate the pile hole and backfill the pile hole with sand.

[0041] S2. Use a pile driver to drive the steel sheet piles into the sandy soil, 50 to 80 cm each time, and keep the steel sheet piles vibrating for 1 to 5 minutes at a frequency of 20 to 40 Hz. For areas with insufficient density, increase the vibration time by 30 to 60 seconds at a frequency of 40 Hz, or pull out part of the steel sheet piles and then drive them in again, or insert a small vibrating rod to make them denser.

[0042] On the basis of the above technical solution, preferably, optical fiber is used to detect the density of backfill sand, and before construction, a simulation verification of steel sheet piles is performed, which includes the following steps:

[0043] P1. Prepare a model box and fill it with sand;

[0044] P2, insert the steel sheet piles into the sand at different depths and use a loading device to apply an axial load to the steel sheet piles;

[0045] P3, record the strain data of the optical fiber and calibrate the conversion relationship between strain and axial force;

[0046] P4. Calculate the side resistance and end resistance values ​​at each insertion depth based on the experimental data, and draw the curves of the maximum end resistance and side resistance changing with the insertion depth under different sand compaction conditions;

[0047] P5. Through comparative analysis, the relationship curve between end resistance, side resistance and relative density of sand and soil is established to provide a calibration basis for evaluating the density of sand and soil during construction.

[0048] The steel sheet pile structure and its preparation and construction method of the present invention have the following beneficial effects compared with the prior art:

[0049] (1) By arranging a protective shell on the pile body and arranging a head cone at the end of the optical fiber, the end of the optical fiber can be embedded in the protective shell through the head cone. After the optical fiber is wrapped with a fiber cloth and bonded to the pile body, due to the protective effect of the protective shell and the embedding effect of the head cone and the protective shell, when piling is carried out, the friction force is mainly borne by the protective shell and the fiber cloth, so that the optical fiber is not separated or damaged, and the stability of the reference is effectively improved;

[0050] (2) The head cone includes three parts: a profiling section, a transition section, and a bonding section. The profiling section is used to fit into the protective shell, while the bonding section is bonded to the fiber cloth together with the optical fiber. In this way, after the fiber cloth is bonded to the pile body, the overall structure is more stable, and there will be no gap between the optical fiber and the head cone, thereby avoiding the problem of the optical fiber and the head cone being separated during pile driving. The structural design of the transition section with a reduced diameter can reduce the pile driving resistance, avoid the head cone from being separated from the protective shell, and also facilitate the extraction of the steel sheet pile.

[0051] (3) By setting a first screw, the head cone and the pile body can be fixed, thereby strengthening the structural strength of the connection between the head cone and the pile body to avoid the problem of the head cone and the protective shell being separated due to the force on the profiling section;

[0052] (4) By providing a T-shaped groove at the end of the fiber cloth, the end of the fiber cloth can be separated to bypass the optical fiber and be arranged between the head cone and the pile body. When the head cone is connected by the first screw, the end of the fiber cloth can be clamped and fixed, thereby further preventing the fiber cloth from being separated due to friction;

[0053] (5) By arranging a second screw on the head cone, when the second screw is screwed into the head cone, the pressing sheet of the fiber cloth can be pushed into the blind hole of the pile body, so as to further fix the end of the fiber cloth and improve the stability of the laying of the fiber cloth;

[0054] (6) In this construction method, the compaction state of the sand can be monitored and judged, and because simulation verification is carried out in advance, this provides a calibration basis for monitoring and judgment during construction, which can improve the accuracy of monitoring the compaction degree of the sand. During the piling process, it can ensure that the construction requirements are met, reduce the rework rate and related safety risks, thereby ensuring the construction quality and safety, and has important engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0056] Figure 1 is a perspective view of a steel sheet pile of the present invention;

[0057] Figure 2 It is a front view of the steel sheet pile of the present invention;

[0058] Figure 3 For the present invention Figure 2 Truncated schematic diagram;

[0059] Figure 4 For the present invention Figure 3 Middle AA section view;

[0060] Figure 5 For the present invention Figure 4 A magnified view of the structure at point A;

[0061] Figure 6 For the present invention Figure 3 Middle BB section;

[0062] Figure 7 For the present invention Figure 6 A magnified view of the structure at point B;

[0063] Figure 8 It is a schematic diagram of the local explosion structure of the steel sheet pile of the present invention;

[0064] Fig. 9 A perspective view of a head cone of a steel sheet pile according to the present invention;

[0065] Fig.10 This is a bottom structural diagram of the head cone of the steel sheet pile of the present invention;

[0066] Fig.11 This is a structural diagram of the fiber cloth of the steel sheet pile of the present invention;

[0067] Fig.12 It is a structural diagram of the protective shell of the steel sheet pile of the present invention;

[0068] Fig.13 This is a fiber optic layout structure diagram of a steel sheet pile of the present invention;

[0069] Fig.14 It is a construction flow chart;

[0070] Fig.15 It is a relatively dense calibration curve diagram;

[0071] Fig.16 The relative density distribution curve along the depth of the backfill soil in the lead hole is used to evaluate the vibration process.

[0072] In the figure: 1, pile body; 101, blind hole; 2, protective shell; 21, shell; 22, cone plate; 201, opening; 3, optical fiber; 4, fiber cloth; 41, first protrusion; 42, second protrusion; 431, pressing piece; 43, holding portion; 401, T-slot; 5, head cone; 51, contour section; 52, transition section; 53, bonding section; 501, threaded hole; 6, first screw; 7, second screw. DETAILED DESCRIPTION

[0073] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0074] like Figures 1 to 13 As shown, the steel sheet pile of the present invention includes a pile body 1, a protective shell 2, an optical fiber 3, a fiber cloth 4, a head cone 5, a first screw 6 and a second screw 7.

[0075] like Figures 1 to 7 As shown, a protective shell 2 is provided at one end of the pile body 1, and an opening 201 is provided on one side of the protective shell 2; an optical fiber 3 is laid on the pile body 1; a fiber cloth 4 is bonded to the pile body 1 and covers the optical fiber 3; a head cone 5 is provided on one end of the optical fiber 3 facing the protective shell 2 and is embedded in the protective shell 2;

[0076] As in the above structure, the optical fiber 3 is bonded to the pile body 1 by an adhesive and is covered by a fiber cloth 4 to achieve a protective effect. A head cone 5 is integrated at the end of the optical fiber 3, and the head cone 5 is embedded in the protective shell 2;

[0077] When piling is being performed, the opening 201 of the protective shell 2 faces upward, so that the sand is broken through the protective shell 2, thereby preventing the end of the fiber cloth 4 from being detached due to excessive friction during piling, thereby ensuring a good protection effect for the optical fiber 3;

[0078] At the same time, in this structure, after the optical fiber 3 is integrated with the head cone 5, it can be directly embedded in the protective shell 2 without the need for other fixed structures to connect with the protective shell 2, thereby effectively improving the convenience of integration.

[0079] like Fig.12 As shown, the protective shell 2 includes a shell 21 and a cone plate 22, wherein the shell 21 is a semicircular shell structure, the shell 21 is buckled on the pile body 1, and an opening 201 is left; the cone plate 22 is arranged on a side of the shell 21 away from the head cone 5;

[0080] As shown in the above structure, the protective shell 2 includes two parts: a shell 21 and a cone plate 22, wherein the shell 21 is welded and fixed to the pile body 1, and the cone plate 22 is welded and fixed to the shell 21 and the pile body 1, and the end of the cone plate 22 away from the shell 21 is a pointed end, so that when piling is carried out, the cone plate 22 can be relied on to break the sand and soil, thereby reducing the pile driving resistance, which is beneficial to avoid the deformation problem of the protective shell 2.

[0081] like Fig. 9 and Fig.10 As shown, the head cone 5 includes a profiling section 51, a transition section 52 and a bonding section 53, wherein the profiling section 51 is arranged in the protective shell 2, the profiling section 51 fits the inner wall of the protective shell 2 and the pile body 1, and the profiling section 51 extends to the outside of the protective shell 2; the transition section 52 is arranged on one end of the profiling section 51 located on the outside of the protective shell 2; the bonding section 53 is arranged on one end of the transition section 52 away from the profiling section 51, and the fiber cloth 4 wraps the bonding section 53;

[0082] As described above, the head cone 5 includes three parts: a contoured section 51, a transition section 52, and a bonding section 53. When integrated, the end of the optical fiber 3 can be integrated into the bonding section 53, or integrated into the transition section 52 and the bonding section 53, or directly integrated with the three parts of the entire head cone 5;

[0083] During assembly, the profiling section 51 is embedded in the protective shell 2, and the radius of the profiling section 51 is as close to the radius of the protective shell 2 as possible, and the difference in radius between the two is as small as possible, thereby reducing the pile driving resistance and facilitating the subsequent extraction of the steel sheet piles.

[0084] The transition section 52 connects the profiling section 51 and the bonding section 53, wherein the radius of the profiling section 51 is larger than the radius of the bonding section 53, the radius of the bonding section 53 is as close to the radius of the optical fiber 3 as possible, and the transition section 52 is a smooth transition;

[0085] Such a structure, firstly, can make the fiber cloth 4 be well bonded with the bonding section 53 to reduce the gap between the optical fiber 3 and the head cone 5; secondly, when pulling out the steel sheet pile, the smooth transition of the transition section 52 can reduce the stress on the head cone 5 and the protective shell 2, thereby avoiding the problem of the protective shell 2 and the head cone 5 falling off and causing damage to the optical fiber 3.

[0086] like Figure 5 and Figure 8 As shown, the first screw 6 is arranged on a surface of the pile body 1 away from the head cone 5, and the first screw 6 passes through the pile body 1 and is screwed together with the head cone 5 through a thread;

[0087] As in the above structure, by setting the first screw 6, the head cone 5 and the pile body 1 can be fixed, so as to strengthen the connection structure strength between the head cone 5 and the pile body 1, thereby avoiding the problem of the head cone 5 and the protective shell 2 being separated due to the force of the profiling section 51, and ensuring the stability of the assembly of the head cone 5;

[0088] Specifically, the first screw 6 is a countersunk screw.

[0089] like Fig.11 As shown, the fiber cloth 4 is in a strip-shaped structure, and the fiber cloth 4 includes a first protrusion 41, a second protrusion 42 and a holding portion 43, wherein the first protrusion 41 is formed by the fiber cloth 4 wrapping the optical fiber 3; the second protrusion 42 is formed by the fiber cloth 4 wrapping the bonding section 53; the holding portion 43 is arranged on one side of the second protrusion 42 and is clamped by the pile body 1 and the head cone 5;

[0090] As in the above structure, the fiber cloth 4 is laid flat on the pile body 1, and forms a first protrusion 41 when covering the optical fiber 3, and forms a second protrusion 42 when covering the bonding section 53;

[0091] Part of the fiber cloth 4 on both sides of the first protrusion 31 and the second protrusion 42 is laid flat and bonded to the pile body 1;

[0092] The end of the fiber cloth 4 is pressed against the bottom of the head cone 5 to be clamped and fixed with the pile body 1, thereby further improving the tensile strength of the fiber cloth 4 to avoid the problem of the fiber cloth 4 being separated due to the friction of the sand.

[0093] Specifically, the fiber cloth 4 is made of carbon-based fiber cloth.

[0094] like Figure 8 , Fig. 9 and Fig.11As shown, a T-shaped slot 401 is provided on the fiber cloth 4, wherein the T-shaped slot 401 is provided on the pressing portion 43 to form two pressing sheets 431; the pressing sheets 431 are clamped by the pile body 1 and the head cone 5; a threaded hole 501 is provided on the portion of the profiling section 51 extending to the outside of the protective shell 2, and a blind hole 101 is provided on the pile body 1 corresponding to the threaded hole 501; the second screw 7 is screwed and connected with the threaded hole 501, and the pressing sheet 431 is pushed into the blind hole 101;

[0095] As in the above structure, by providing a T-shaped groove 401 on the pressing portion 43, the fiber cloth 4 can be sleeved on the optical fiber 3 through the T-shaped groove 401, so that the two pressing pieces 431 of the pressing portion 43 can be pressed on the lower side of the head cone 5, and the other part of the fiber cloth 4 covers the optical fiber 3 and the bonding section 53 of the head cone 5, and then is bonded and fixed to the pile body 1 by an adhesive;

[0096] Specifically, the pressing sheet 431 is pressed on the lower side of the transition section 52, and a part of the fiber cloth 4 is bonded to the bonding section 53, thereby avoiding the problem of exposure of the connection between the optical fiber 3 and the head cone 5, thereby ensuring the stability of the application;

[0097] In this structure, by arranging the second screw 7 on the head cone 5, when the second screw 7 is screwed with the head cone 5, the pressing sheet 431 of the fiber cloth 4 can be pushed into the blind hole 101 of the pile body 1, so as to further fix the end of the fiber cloth 4, improve the tensile strength of the fiber cloth 4, and thus ensure the stability of laying;

[0098] The second screw 7 is designed with a countersunk head to reduce the resistance to pile driving and avoid damage.

[0099] like Figure 1 and Fig.13 As shown, the optical fiber 3 is arranged in a straight line or a winding shape on the pile body 1;

[0100] As in the above structure, according to the application requirements, the optical fiber 3 can be arranged on the pile body 1 in a straight line or a winding shape, and a plurality of detection gratings can be integrated; thereby meeting the detection requirements for the pile body 1;

[0101] Specifically, the number of optical fibers 3 is not limited to one, and a plurality of optical fibers 3 may be provided. The optical fibers 3 are not limited to being laid along the length direction of the steel sheet piles, and may also be laid along the width direction of the steel sheet piles.

[0102] like Figures 14 to 16 As shown:

[0103] The method for preparing the steel sheet piles of the present invention comprises the following steps:

[0104] S1, welding a protective shell 2 on the pile body 1, and integrating a head cone 5 at the end of the optical fiber 3;

[0105] S2, grinding the pile body 1 corresponding to the opening 201 of the protective shell 2;

[0106] Specifically, the symmetrical surface of the pile body 1 is fully polished along the layout path to remove surface rust and impurities to ensure that the layout area is flat and clean; if the pile body 1 is concrete, surface stains and oil stains need to be removed to ensure the bonding effect;

[0107] S3, applying adhesive on the polished surface of the pile body 1;

[0108] Specifically, the primer adhesive is evenly applied to the sensor optical cable laying area to lay a good foundation for the stable adhesion of the optical fiber 3. The primer should cover the entire area without leaving any gaps to improve the adhesion between the optical fiber 3 and the pile body 1.

[0109] S4, setting one end of the fiber cloth 4 on the pressing sheet 431, sleeved on the optical fiber 3 through the T-slot 401, and then laid on the pile body 1;

[0110] S5, fitting the nose cone 5 into the protective shell 2;

[0111] S6, passing the first screw 6 through the pile body 1 and screwing it with the head cone 5 to clamp the end of the fiber cloth 4;

[0112] S7, connecting the second screw 7 to the threaded hole 501 of the head cone 5 to partially push the pressing sheet 431 into the blind hole 101 of the pile body 1;

[0113] S8, first lay out the optical fiber 3, then lay out the remaining fiber cloth 4, and roll the fiber cloth 4 to make the fiber cloth 4 firmly bonded by the adhesive;

[0114] Specifically, the optical fiber 3 is placed straight on the base glue along the laying path, and it is noted that the optical fiber 3 should not be bent or twisted, and the line should be kept flat; after the optical fiber 3 is laid, a layer of surface glue adhesive is evenly applied thereon to make the optical fiber 3 better fit the surface of the pile body 1, thereby improving the overall stability of the laying;

[0115] Specifically, after the surface glue adhesive reaches at least 50% of the curing strength, a fireproof material (such as gold foil paper, asbestos cloth, etc.) is pasted on the outer layer of the optical fiber 3 to prevent welding slag and heat from burning the optical cable during subsequent welding operations or construction, thereby ensuring the safety and durability of the optical fiber 3.

[0116] In some embodiments, the protective shell 2 is replaced by a thin steel sheet; specifically, a thin steel sheet is welded at the bottom of the pile body 1 to protect the bottom optical fiber 3 .

[0117] In some embodiments, the bottom of the thin steel sheet should be welded and sealed. Especially in working conditions with coarse-grained soil layers, a thin steel sheet should be added along the entire line of the optical fiber 3 to prevent damage to the optical fiber 3 during piling. To avoid high temperature burning the optical fiber 3 during welding, the width of the thin steel sheet needs to be greater than 8 cm, but this solution is not easy to maintain.

[0118] In some embodiments, the lead-out end of the optical fiber 3 is protected by a sleeve, and a protective column or hook is welded at a fixed position to stabilize the optical fiber 3 and prevent the optical fiber 3 from vibrating and breaking during the piling process. This ensures that the optical fiber 3 is safe and intact during the driving process, providing stable support for subsequent monitoring.

[0119] The steel sheet pile construction method of the present invention uses the above-mentioned steel sheet piles, which comprises the following steps:

[0120] S1. Excavate the pile hole and backfill the pile hole with sand.

[0121] S2. Drive the steel sheet piles into the sand by a pile driver, 50 to 80 cm each time, and keep the steel sheet piles vibrating for 1 to 5 minutes at a frequency of 20 to 40 Hz;

[0122] Among them, for areas with insufficient density, the vibration time is increased by 30 to 60 seconds, the vibration frequency is 40Hz, or the steel sheet piles are partially pulled out and then driven in, or a small vibrating rod is inserted to supplement the density.

[0123] Optical fiber 3 is used to detect the density of backfill sand. Before construction, a simulation verification of the steel sheet pile is carried out, which includes the following steps:

[0124] P1. Prepare a model box and fill it with sand;

[0125] P2, insert the steel sheet piles into the sand at different depths and use a loading device to apply an axial load to the steel sheet piles;

[0126] P3, record the strain data of optical fiber 3, and calibrate the conversion relationship between strain and axial force;

[0127] P4. Calculate the side resistance and end resistance values ​​at each insertion depth based on the experimental data, and draw the curves of the maximum end resistance and side resistance changing with the insertion depth under different sand compaction conditions;

[0128] P5. Through comparative analysis, the relationship curve between end resistance, side resistance and relative density of sand and soil is established to provide a calibration basis for evaluating the density of sand and soil during construction.

[0129] Specifically, through indoor calibration tests, the relationship between strain ε and axial force N is established:

[0130] N=EAε (1) Where: E is the elastic modulus of steel, A is the cross-sectional area of ​​the steel sheet pile. When there are multiple measuring lines, N takes the average value.

[0131] Calculate the lateral friction of each soil layer according to the axial force difference between adjacent measuring points:

[0132]

[0133] Where: f s is the side friction resistance, ΔN is the axial force difference, u is the pile circumference, and Δl is the calculation section length.

[0134] The pile end resistance is determined by the axial force at the lowest measuring point:

[0135]

[0136] Where: q p is the end resistance, N p is the axial force at the pile end, A p is the pile tip area.

[0137] The relative density D is obtained by indoor calibration curve fitting n The relationship is as follows:

[0138]

[0139] Where: Steel sheet pile end resistance q c , sandy soil deadweight σ, sandy soil relative density D n

[0140] In this method, at least two optical fibers 3 are arranged on the steel sheet pile to form a U-shaped loop. The end of the steel sheet pile has at least 1 meter of optical fiber 3 for end resistance and side resistance testing. The grating spacing is less than 20 cm, and the remaining grating spacing is 50 cm to 100 cm.

[0141] In this construction method, the compaction state of sand can be monitored and judged, and because simulation verification is carried out in advance, this provides a calibration basis for monitoring and judgment during construction, which can improve the accuracy of monitoring the compaction degree of sand, and ensure that construction requirements are met during the piling process, reducing the rework rate and related safety risks, thereby ensuring construction quality and safety, and having important engineering application value.

[0142] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A steel sheet pile, characterized in that: It comprises a pile body (1), a protective shell (2), an optical fiber (3), a fiber cloth (4) and a head cone (5), wherein: The protective shell (2) is provided at one end of the pile body (1), and one side of the protective shell (2) has an opening (201); The optical fiber (3) is laid on the pile body (1); The fiber cloth (4) is bonded to the pile body (1) and covers the optical fiber (3); The head cone (5) is arranged on one end of the optical fiber (3) facing the protective shell (2) and is embedded in the protective shell (2).

2. The steel sheet pile according to claim 1, characterized in that: The protective shell (2) comprises a shell (21) and a cone plate (22), wherein: The shell (21) is a semicircular shell structure, the shell (21) is buckled on the pile body (1) and has the opening (201); The cone plate (22) is arranged on a side of the housing (21) away from the nose cone (5).

3. The steel sheet pile according to claim 2, characterized in that: The nose cone (5) comprises a contoured section (51), a transition section (52) and a bonding section (53), wherein: The profiling section (51) is arranged in the protective shell (2), the profiling section (51) fits the inner wall of the protective shell (2) and the pile body (1), and the profiling section (51) extends to the outside of the protective shell (2); The transition section (52) is arranged on one end of the contour section (51) located outside the protective shell (2); The bonding section (53) is arranged on an end of the transition section (52) away from the contour section (51), and the fiber cloth (4) wraps the bonding section (53).

4. The steel sheet pile according to claim 3, characterized in that: It also comprises a first screw (6), which is arranged on a surface of the pile body (1) away from the head cone (5), and the first screw (6) passes through the pile body (1) and is screwed together with the head cone (5) through a thread.

5. The steel sheet pile according to claim 4, characterized in that: The fiber cloth (4) is in a strip-shaped structure, and comprises a first protruding portion (41), a second protruding portion (42) and a pressing portion (43), wherein: The first protrusion (41) is formed by wrapping the optical fiber (3) with the fiber cloth (4); The second protruding portion (42) is formed by wrapping the bonding section (53) with the fiber cloth (4); The pressing portion (43) is arranged on one side of the second protruding portion (42) and is clamped by the pile body (1) and the head cone (5).

6. The steel sheet pile according to claim 5, characterized in that: It also includes a second screw (7), and the fiber cloth (4) is provided with a T-shaped slot (401), wherein: The T-shaped groove (401) is provided on the pressing portion (43) to form two pressing sheets (431); The pressing sheet (431) is clamped by the pile body (1) and the head cone (5); A threaded hole (501) is formed on the portion of the contoured section (51) extending to the outside of the protective shell (2), and a blind hole (101) is formed on the pile body (1) corresponding to the threaded hole (501); The second screw (7) is screwed into the threaded hole (501) and pushes the pressing sheet (431) into the blind hole (101).

7. The steel sheet pile according to any one of claims 1 to 6, characterized in that: The optical fiber (3) is arranged in a straight line or a winding shape and laid on the pile body (1).

8. A method for preparing the steel sheet pile according to claim 6, characterized in that: The following steps are involved: S1, welding the protective shell (2) on the pile body (1), and integrating the head cone (5) at the end of the optical fiber (3); S2, grinding the pile body (1) corresponding to the opening (201) of the protective shell (2); S3, applying an adhesive to the polished surface of the pile body (1); S4, placing the fiber cloth (4) on one end of the pressing sheet (431), sleeved onto the optical fiber (3) through the T-shaped groove (401), and then laid on the pile body (1); S5, fitting the nose cone (5) into the protective shell (2); S6, passing the first screw (6) through the pile body (1), and screwing it to the head cone (5) through a thread, so as to clamp the end of the fiber cloth (4); S7, connecting the second screw (7) to the threaded hole (501) of the head cone (5) to partially push the pressing sheet (431) into the blind hole (101) of the pile body (1); S8, first lay out the optical fiber (3), then lay out the remaining fiber cloth (4), and roll the fiber cloth (4) so ​​that the fiber cloth (4) is firmly bonded by an adhesive.

9. A steel sheet pile construction method, characterized in that: The steel sheet pile according to any one of claims 1 to 7 is used, which comprises the following steps: S1. Excavate the pile hole and backfill the pile hole with sand. S2, driving the steel sheet piles into the sand by a pile driver, driving 50 to 80 cm each time, and keeping the steel sheet piles vibrating for 1 to 5 minutes at a vibration frequency of 20 to 40 Hz; Among them, for areas with insufficient density, the vibration time is increased by 30 to 60 seconds, the vibration frequency is 40 Hz, or the steel sheet piles are partially pulled out and then driven in, or a small vibrating rod is inserted to supplement the density.

10. The steel sheet pile construction method according to claim 9, characterized in that: The optical fiber (3) is used to detect the density of the backfill sand. Before construction, a simulation verification is performed on the steel sheet pile, which includes the following steps: P1. Prepare a model box and fill it with sand; P2, inserting the steel sheet piles into the sand at different depths, and applying an axial load to the steel sheet piles using a loading device; P3, recording the strain data of the optical fiber (3) and calibrating the conversion relationship between the strain and the axial force; P4. Calculate the side resistance and end resistance values ​​at each insertion depth based on the experimental data, and draw the curves of the maximum end resistance and side resistance changing with the insertion depth under different sand compaction conditions; P5. Through comparative analysis, the relationship curve between end resistance, side resistance and relative density of sand and soil is established to provide a calibration basis for evaluating the density of sand and soil during construction.

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