Settlement Monitoring Method for Upstream Rockfill Zone of High Earth-Rock Dam

Abstract

The present invention provides a method for monitoring the settlement of the upstream rockfill area of ​​a high earth-rock dam, and the settlement monitoring method includes a method for installing and burying a flexible inclinometer, a method for installing and burying an optical fiber pressure gauge, and a method for installing and burying an ultra-wideband radar monitoring system; the flexible inclinometer is buried horizontally to monitor the settlement distribution of the upstream rockfill along the direction of the water flow; the optical fiber pressure gauge is buried in layers in the upstream dam slope and the rockfill area to monitor the settlement of different parts and elevations of the upstream rockfill in all directions; the foundation of the ultra-wideband radar monitoring system is mainly used as a detection benchmark for the flexible inclinometer, and the measured values ​​of each measuring point of the flexible inclinometer are corrected by the settlement of the foundation. The flexible inclinometer and the optical fiber pressure gauge are arranged in a system monitoring manner, and the elevation values ​​of the benchmark points are obtained in real time in cooperation with the ultra-wideband radar monitoring system, forming settlement monitoring of the upstream rockfill area. The technical solution can automatically read all monitoring instrument data, avoid the disadvantages of manual data collection after water storage, and realize monitoring automation.

Description

Technical Field

[0001] The present invention relates to the field of safety monitoring of earth-rock dams, and particularly to a method for monitoring the settlement of the upstream rockfill area of high earth-rock dams. Background Art

[0002] In recent years, the domestic hydropower dam construction technology has developed rapidly. In typical earth-rock dam projects, the dam height of gravel soil core wall rockfill dams has been gradually increased from the 100m level to the 300m level. After impoundment, the upstream rockfill area is affected by water, and wetting deformation will occur. Excessive deformation may affect the stability of the dam slope. Therefore, the settlement of the upstream rockfill area of domestic high earth-rock dams after impoundment has received increasing attention. Currently, the settlement of the upstream rockfill area is generally monitored by piezometers, vibrating wire settlement gauges, crossbeam settlement gauges, and electromagnetic settlement rings. However, these monitoring methods can only monitor the settlement during the construction period. After impoundment, the vibrating wire settlement gauges, crossbeam settlement gauges and other electrical measurement monitoring instruments arranged in the upstream rockfill area are basically ineffective. For the traditional electromagnetic settlement ring, the reading instrument needs to be manually placed into the hole, so it is impossible to carry out observations. The piezometer is also unable to observe due to being flooded by the impounded water. Therefore, the settlement monitoring of the upstream rockfill area after impoundment, especially the wetting deformation monitoring, has always been a blank area. A well-known domestic instrument manufacturer has developed an intelligent settlement gauge to monitor the rockfill settlement after impoundment, but the effect is not good in actual engineering applications. Some experts and scholars have also proposed to arrange piezometers in the upstream rockfill area and calculate the rockfill settlement by indirectly measuring the water pressure at the location. However, due to the instrument accuracy and the actual complex impoundment situation, the application effect is not ideal. Therefore, it is very necessary and urgent to adopt new monitoring technology means to solve the problem of settlement monitoring of the upstream rockfill area after impoundment. Summary of the Invention

[0003] The main purpose of the present invention is to provide a method for monitoring the settlement of the upstream rockfill area of high earth-rock dams to solve the problems in the above background art.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is that the settlement monitoring method includes the installation and embedding method of a flexible inclinometer, the installation and embedding method of an optical fiber pressure gauge, and the installation and embedding method of an ultra-wideband radar monitoring system;

[0005] The flexible inclinometer is horizontally embedded and used to monitor the settlement distribution of the upstream rockfill area along the water flow direction;

[0006] The optical fiber pressure gauges are embedded in layers on the upstream dam slope and in the rockfill area to comprehensively monitor the settlement of different parts and elevations of the upstream rockfill;

[0007] The foundation of the ultra-wideband radar monitoring system mainly serves as the detection reference for the flexible inclinometer, and the measured values of each measuring point of the flexible inclinometer are corrected by the settlement of this foundation.

[0008] In a preferred embodiment, the flexible inclinometer comprises a casing, in which a precision inclinometer and a roughness inclinometer are installed, a connecting end is provided at one end of the casing, a connecting rod is provided at one end of the connecting end, a universal joint is provided at one end of the connecting rod, and the connecting end is connected to the casing by a plurality of bolts;

[0009] A coarse measuring device and a fine measuring wire are connected between two adjacent flexible inclinometers;

[0010] Precision inclinometers are used to measure small displacements and are used for dams with small axial settlements of the core wall;

[0011] The coarseness inclinometer is used to measure large displacements. When the axial settlement of the dam core wall is too large, the fine measurement wire breaks and the spring-loaded coarse measurement wire extends to perform a coarse measurement of the dam settlement.

[0012] In the preferred embodiment, the steps of the flexible inclinometer installation and embedding method are as follows:

[0013] S1. Mechanically excavate a horizontal trench from the upstream rockfill area to the upstream transition layer at 2 / 3 of the height of the dam monitoring cross section;

[0014] S2, level the trench bed, then backfill fine material from the bottom of the trench, and mechanically roll it flat;

[0015] S3. A prefabricated concrete foundation is buried in the upstream transition material, a lifting ring is pre-buried on the side of the foundation, the flexible inclinometer and the lifting ring are fixedly connected by a movable hinge joint, and a protective cover is set at the connection;

[0016] S4. The upstream rockfill area is constructed in sections and elevations, and the flexible inclinometer is installed and buried in sections. The ends of each section of the flexible inclinometer are connected by movable hinges;

[0017] S5. After the installation is completed, carry out relevant instrument performance inspection tests. If the inspection and test are qualified, backfill the trench.

[0018] In the preferred solution, in S4, the flexible inclinometer is installed and buried with flexible PE pipe protection, each section of the flexible inclinometer protection pipe is a whole pipe, and each flexible inclinometer connection head is protected by a PE pipe outer jacket.

[0019] In the preferred solution, in S5, the trench is backfilled by removing fine materials with a particle size of more than 5 cm and backfilling the trench in layers of 20 cm per layer, and each layer is compacted by vibrating tamping;

[0020] When the filling surface is 1m higher than the instrument burial elevation, resume normal filling of the dam.

[0021] In the preferred embodiment, the steps of the method for installing and burying the optical fiber pressure gauge are as follows:

[0022] A1. Install fiber optic piezometers at three typical elevations in the upstream rockfill area. The fiber optic piezometers share the trench for burial with other monitoring instruments. If conditions do not permit, they can be buried in a separately dug pit.

[0023] A2. After the fiber optic piezometers pass the test inspection before on-site installation, they are wrapped with geotextiles and fine sand and gravel, and horizontally buried in the pit or trench. The elevation of burial needs to be accurately recorded during burial.

[0024] A3. Then backfill with fine materials to the top of the pit. The instrument optical cable is sleeved with a PE pipe and horizontally towed along the trench to the upstream dam slope, and then towed along the upstream dam slope to the dam top observation room.

[0025] In the preferred solution, the steps of the installation and burial method of the ultra-wideband radar monitoring system are as follows:

[0026] B1. Burry a steel plate at the concrete pedestal. The steel plate is fixed by expansion bolts, and a galvanized steel pipe is welded to the steel plate. The steel pipe is vertically extended as the rockfill is filled.

[0027] B2. Record the length of the steel pipe in detail each time it is extended. Install an ultra-wideband radar monitoring point at the pipe opening to obtain the accurate elevation of the pipe opening in real time. The foundation elevation can be calculated through the length of the steel pipe.

[0028] In the preferred solution, if the ultra-wideband radar monitoring system does not meet the operating conditions in B2, a fixed prism can be used instead, and the elevation of the pipe opening is measured by a total station.

[0029] In the preferred solution, the basic principle of the flexible inclinometer is that by detecting the gravitational field of each part, the bending angle θ between each section of the axis can be calculated. Using the calculated bending angle and the known length L of each section of the axis, the deformation Δχ of each section of SAA can be determined, that is, Δχ = θ • L. Then, by arithmetically summing each section ∑Δχ, the deformation χ at any length from the fixed end point can be obtained.

[0030] In the preferred solution, the principle of the fiber optic piezometer for monitoring settlement is to first accurately measure its installation elevation H1 (m), record the stable water level H2 (m) of the upstream rockfill after impoundment, and obtain the actual elevation H3 = H2 - h * 100 of the fiber optic piezometer after impoundment by reading the reading h (MPa) of the fiber optic piezometer. Then, the settlement amount H at the location of the fiber optic piezometer is obtained as H = H1 - H3.

[0031] The present invention provides a method for monitoring the settlement of the upstream rockfill area of a high earth-rock dam, and the beneficial effects are as follows:

[0032] (1) All the original monitoring techniques in the upstream rockfill area were only applicable during the construction period. After impoundment, most of the original monitoring means became ineffective, leaving the settlement monitoring of the upstream rockfill area after impoundment as a blind spot. This technical solution can not only monitor the settlement during the construction period (relying on flexible inclinometers and ultra-wideband radars to monitor settlement during the construction period), but also monitor the settlement during the impoundment period and the operation period, effectively solving the problem of settlement monitoring in the upstream rockfill area.

[0033] (2) This technical solution not only realizes the settlement monitoring of the upstream rockfill area after impoundment, but also enables automated monitoring, facilitating observations during the impoundment period and the operation period, and avoiding the risks of manual observations.

[0034] (3) This technical solution abandons the deficiencies of traditional technical means and creatively proposes a technical means of using a new type of monitoring instrument, namely, a flexible inclinometer + fiber optic pressure gauge + ultra-wideband radar monitoring system. The flexible inclinometer is used to monitor the linear distribution of horizontal settlement in the upstream rockfill area, and the fiber optic pressure gauge with a cm-level monitoring accuracy is used to monitor the three-dimensional settlement in the upstream rockfill area, which also complements the flexible inclinometer. More importantly, the use of the ultra-wideband radar effectively solves the problem of the settlement monitoring reference of the flexible inclinometer and facilitates the implementation of automation, making this technical solution highly feasible. This technical solution solves the problem of settlement monitoring in the upstream rockfill area during the impoundment period and improves the monitoring technology level of earth-rock dams. Description of the Drawings

[0035] The present invention will be further described below in conjunction with the drawings and embodiments:

[0036] Figure 1 It is a schematic diagram of the settlement monitoring structure of the upstream rockfill area of a high earth-rock dam during the impoundment period of the present invention;

[0037] Figure 2 It is a partially enlarged view of the settlement monitoring of the upstream rockfill area of a high earth-rock dam during the impoundment period of the present invention;

[0038] Figure 3 It is a connection diagram of two flexible inclinometers of the present invention;

[0039] Figure 4 It is a left view of the rough measurement device of the present invention;

[0040] Figure 5 It is an axonometric view of a small section at the end of the rough measurement device of the present invention;

[0041] Figure 6 It is a cross-sectional view of the rough measurement wire of the present invention;

[0042] Figure 7 It is an axonometric view of the connector of the present invention;

[0043] Figure 8 It is a cross-sectional view of the connector of the present invention;

[0044] In the figure: casing 1; precision inclinometer 2; roughness inclinometer 3; connection end 4; end body 401; first cavity 402; connection head 403; housing 4031; second cavity 4032; annular groove 4033; circular groove 4034; connecting rod 5; rough measurement device 6; rough measurement wire 601; battery cell 6011; insulating layer 6012; waterproof layer 6013; flexible steel wire 602; ball 603; universal joint 7; fine measurement wire 8; bolt 9. Specific embodiments

[0045] As Figures 1 to 8 shown, this technical solution proposes to use a flexible inclinometer + F-P fiber optic pressure gauge + ultra-wideband radar to systematically monitor the settlement of the upstream rockfill area, which is applicable to the settlement monitoring of the upstream rockfill area of earth-rock dams with a dam height of 50m to 350m.

[0046] The array displacement gauge SAA, commonly known as a flexible inclinometer, is composed of multiple consecutive segments connected in series and internally consists of a microelectromechanical system (MEMS) accelerometer. Each segment has a fixed length, generally 50 cm or 100 cm.

[0047] In a preferred solution, the flexible inclinometer includes a casing 503. Inside the casing 503, a precision inclinometer 2 and a roughness inclinometer 3 are installed. One end of the casing 503 is provided with a connection end 4. One end of the connection end 4 is provided with a connecting rod 5. One end of the connecting rod 5 is provided with a universal joint 7. The connection end 4 is connected to the casing 503 through a plurality of bolts 9;

[0048] A rough measurement device 6 and a fine measurement wire 8 are connected between two adjacent flexible inclinometers;

[0049] The precision inclinometer 2 is used to measure small displacements and is used for the relatively small axial settlement of the dam core wall;

[0050] The roughness inclinometer 3 is used to measure large displacements. When the axial settlement of the dam core wall is too large and the fine measurement wire 8 breaks, the spring-type rough measurement wire 601 elongates to roughly measure the dam settlement. With this structure, when the axial settlement of the dam core wall is small and the settlement of the dam is not sufficient to break the connecting rod 5 and the fine measurement wire 8 between the flexible inclinometers, the flexible inclinometer can accurately measure the axial settlement of the dam core wall.

[0051] When the axial settlement of the core wall of a high earth-rock dam is too large, exceeding 30 - 50 cm, the connecting rods 5 and the precise measuring wires 8 of two adjacent flexible inclinometers break. At this time, the rough measuring inclinometer 3 measures the large displacement of the core wall of the high earth-rock dam. The rough measuring wire 601 is in a spring shape, and the length of the rough measuring wire 601 is relatively long, which can adapt to the large displacement of the axial settlement of the dam core wall. When the settlement of the dam is too large, under the action of tension, the two adjacent flexible inclinometers pull the flexible steel wires 602 wound outside the rough measuring wire 601, so that the rough measuring device 6 changes from a spring shape to a straight shape and elongates. At this time, the rough measuring wire 601 is close to a straight line, and multiple flexible steel wires 602 are wound on the straight rough measuring wire 601, so that the overall structure can measure a larger dam settlement.

[0052] When the axial settlement of the core wall of the high earth-rock dam further expands, exceeding 50 cm, under the action of tension, the two adjacent flexible inclinometers pull the flexible steel wires 602 wound outside the rough measuring wire 601, so that the rolling balls 603 at the ends of the flexible steel wires 602 roll in the circular grooves 4034, so that multiple flexible steel wires 602 are straightened. Under the action of force, the rough measuring wire 601 wound in the casing 503 is pulled from the casing 503 into multiple straightened flexible steel wires 602, so that the stretchable deformation amount of the two adjacent flexible inclinometers is further expanded, so that the flexible inclinometer can detect a larger deformation amount, and the full cross-section detection of the dam core wall is more comprehensive.

[0053] In addition to being able to extend the effective measuring distance between two adjacent flexible inclinometers, multiple flexible steel wires 602 can also play a protective role for the rough measuring wire 601, and can effectively solve the problems of possible rupture of the PE protection pipe 13, the settlement pressure of the dam soil, or the breakage of the connecting rod 5 during the settlement of the dam, which may cause the rough measuring wire 601 to break. It can effectively avoid the phenomenon that the axial settlement of the core wall of the high earth-rock dam is too large, the rough measuring wire 601 breaks, and the flexible inclinometer fails.

[0054] In the preferred solution, the connection end 4 includes an end body 401, and a first cavity 402 is provided on the end body 401. The precise measuring wire 8 passes through the first cavity 402 and is connected to two adjacent precision inclinometers 2. With this structure, the first cavity 402 is used for the precise measuring wire 8 to pass through. When the settlement of the dam is relatively small, the precise measuring wire 8 is connected to the precision inclinometer 2, and the precision of the precision inclinometer 2 is higher, and it is more suitable for the situation where the deformation amount of the dam is less.

[0055] In a preferred embodiment, a connector 403 is provided on the connection end 4. The connector 403 includes a housing 4031. One end of the housing 4031 is provided with an annular groove 4033. One end of the annular groove 4033 is provided with an annular circular groove 4034. A through second cavity 4032 is provided in the middle of the housing 4031. With this structure, the second cavity 4032 is used for roughly measuring the passage of the wire 601. The annular groove 4033 is used for the end of the flexible steel wire 602 to slide. The circular groove 4034 is used for the rolling ball 603 to roll in the annular circular groove 4034, so that when the settlement of the dam is relatively large, the flexible steel wire 602 can rotate under the action of force, so that the axial distance of the flexible steel wire 602 becomes longer.

[0056] In a preferred embodiment, the rough measurement device 6 includes a roughly measuring wire 601 having a spring-like structure. A plurality of flexible steel wires 602 are provided outside the roughly measuring wire 601. The plurality of flexible steel wires 602 are wound around and wrap the spring-like roughly measuring wire 601. Rolling balls 603 are provided at both ends of the flexible steel wire 602. Both ends of the flexible steel wire 602 abut against the annular groove 4033. The rolling balls 603 abut against and slide in the annular circular groove 4034. Both ends of the roughly measuring wire 601 respectively penetrate through the adjacent second cavities 4032 and are connected to the adjacent two rough inclinometers 3. The redundant parts at both ends of the roughly measuring wire 601 are wound inside the sleeve 503. With this structure, the plurality of flexible steel wires 602 have a certain elasticity. When the roughly measuring wire 601 penetrates through the plurality of flexible steel wires 602, the flexible steel wires 602 can support the roughly measuring wire 601, so that the plurality of flexible steel wires 602 maintain a spring-like shape.

[0057] When the axial settlement of the core wall of the high earth-rock dam further expands and exceeds 50 cm, under the action of tension, two adjacent flexible inclinometers pull the flexible steel wires 602 wound outside the roughly measuring wire 601, so that the rolling balls 603 at the ends of the flexible steel wires 602 roll in the circular groove 4034, so that the plurality of flexible steel wires 602 are straightened, so that the roughly measuring wire 601 wound in the sleeve 503 is pulled into the plurality of straightened flexible steel wires 602 under the action of force, so that the stretchable deformation amount of the two adjacent flexible inclinometers is further expanded, so that the flexible inclinometer can detect a larger deformation amount, so that the full-section detection of the dam core wall is more comprehensive.

[0058] In a preferred embodiment, the roughly measuring wire 601 includes a core 6011 at the center. An insulating layer 6012 is provided outside the core 6011. A waterproof layer 6013 is provided outside the insulating layer 6012. With this structure, the insulating layer 6012 is used to ensure normal signals when two adjacent flexible inclinometers use the roughly measuring wire 601 and avoid interference from other factors to the signals of the roughly measuring wire 601. The waterproof layer 6013 is used to isolate the influence of the water in the dam on the roughly measuring wire 601.

[0059] The flexible inclinometer is a rigid sensing array separated by flexible joints. The flexible inclinometer is a rope-like array of sensors and microprocessors, and all the microprocessors in the array share the same digital communication line.

[0060] The basic principle of the flexible inclinometer is that by detecting the gravitational fields of various parts, the bending angles θ between the axes of each section can be calculated. Using the calculated bending angles and the known lengths L of each section of the axis, the deformation Δχ of each section of the SAA can be completely determined, that is, Δχ = θ • L. Then, by arithmetically summing ∑Δχ for each section, the deformation χ at any length from the fixed end point can be obtained.

[0061] The flexible inclinometer has technical advantages such as high precision, high stability, large deformation, non-uniform deformation, and high water pressure resistance, and has been widely used in slope, tunnel, subgrade, and bridge deformation monitoring. Since the flexible inclinometer can withstand a water pressure of 2 MPa and can work normally underwater, it can be used to monitor the settlement of rockfill after impoundment.

[0062] The F-P pressure-sensitive chip inside the wavelength-type MEMS fiber F-P pressure sensor is fabricated based on MEMS microfabrication technology. Since the wavelength signal demodulation method has a more sensitive detection ability for the cavity length change of the F-P sensitive cavity, it takes into account the measurement accuracy, over-range capacity, mechanical reliability, and dynamic measurement response ability of the MEMS pressure sensor. The pressure sensor has the characteristics of small size, high precision, high measurement linearity, high sensitivity, good dynamic characteristics, small temperature drift, good environmental adaptability, long-term stability, convenient installation, intrinsic safety, etc. It is not affected by electromagnetic interference and lightning damage, and the measurement accuracy and resolution are not affected by the light source fluctuation and the bending loss of the transmission line. The signal can be remotely transmitted directly through the optical fiber. Based on the wavelength-type MEMS fiber F-P pressure sensor (hereinafter referred to as the fiber optic pressure gauge), the calibrated full-scale accuracy in the laboratory can reach two ten-thousandths, that is, the water level observation accuracy for a 1 MPa range can reach 2 cm accuracy.

[0063] The principle of the fiber optic pressure gauge for monitoring settlement is to first accurately measure its installation elevation H1 (m), record the stable water level of the upstream rockfill after impoundment (generally measured by a water gauge) H2 (m), and obtain the actual elevation H3 = H2 - h * 100 of the fiber optic pressure gauge after impoundment by reading the reading h (MPa) of the fiber optic pressure gauge. Then, the settlement amount H at the location of the fiber optic pressure gauge can be obtained as H = H1 - H3.

[0064] Therefore, this technical solution proposes to use a flexible inclinometer + fiber optic pressure gauge + ultra-wideband radar to monitor the settlement of the upstream rockfill area of ​​the dam in all directions. The flexible inclinometer is buried horizontally and is mainly used to monitor the settlement distribution of the upstream rockfill along the direction of the water flow. The fiber optic pressure gauge is buried in layers on the upstream dam slope and the rockfill area to monitor the settlement of different parts and elevations in the upstream rockfill area in all directions. The foundation of the ultra-wideband radar monitoring system is mainly used as the monitoring benchmark of the flexible inclinometer, and the settlement of the foundation is used to correct the measured values ​​of each measuring point of the flexible inclinometer.

[0065] Installation and burial of flexible inclinometer: At 2 / 3 of the dam height of the dam monitoring cross section, a horizontal trench is mechanically excavated from the upstream rockfill area to the upstream transition layer, with a depth of 1.2m and a bottom width of 0.8m. Level the trench bed, then backfill 20cm thick fine material at the bottom of the trench, and mechanically roll it flat. Bury a precast concrete base in the upstream transition material area, with the size of the base (length × width × height) 50cm × 50cm × 20cm. Pre-embed a lifting ring on the side of the base (as an anchor end), and fix the flexible inclinometer and the lifting ring with a movable hinge joint, and set a special protective device (steel pipe cover) at the connection. Generally, the upstream rockfill area adopts segmented and elevation filling construction. In order to reduce the interference of on-site civil construction, the flexible inclinometer is installed and buried in sections (this technical solution is divided into three sections, and similar projects can also be divided into sections according to actual conditions). The ends of each section of the flexible inclinometer are connected with customized movable hinge joints. The flexible inclinometer is protected by a flexible PE pipe with an outer diameter of 60mm and a wall thickness of 4.6mm. The material is a flexible PE100 grade SDR11 pipe. There is no joint in the middle of each section of the flexible inclinometer protection pipe. A 75mm PE pipe is applied to the connector of each flexible inclinometer. During installation, the inner and outer walls of the PE protection pipe are coated with lubricants such as butter, and the pipe ends are sealed with a cover. After the installation is completed, the instrument-related performance inspection and testing are carried out. After the inspection and testing are qualified, the trench is backfilled. The trench backfill is backfilled by removing fine materials (reverse filter material 1) with a particle size of more than 5cm and backfilling the trench in layers of 20cm per layer. Each layer is compacted by a hand-held vibrating rammer. When the filling surface is 1m higher than the buried elevation of the instrument, the normal filling of the dam is resumed.

[0066] Installation and burial of ultra-wideband radar monitoring system: bury steel plates in the concrete base with the specifications of length × width × thickness = 20cm × 20cm × 0.5cm. The steel plates are fixed with expansion bolts, and then the galvanized steel pipes are welded to the steel plates. The steel pipes are vertically extended along with the rockfill. The length of the steel pipes is recorded in detail each time they are extended. Ultra-wideband radar monitoring points are installed at the mouth of the steel pipe (the equipment and the steel pipe are connected with threaded connections) to obtain the accurate elevation of the pipe mouth in real time (if the ultra-wideband radar monitoring system does not meet the operating conditions, it can be replaced with a fixed prism, and the total station is used to measure the elevation of the pipe mouth). The foundation elevation can be calculated through the length of the steel pipe.

[0067] Installation and embedding of fiber optic piezometers: Fiber optic piezometers are installed at three typical elevations in the upstream rockfill area. It is recommended that the fiber optic piezometers share the trench for embedding with other monitoring instruments as much as possible. If conditions do not permit, a separate pit can be dug for embedding. The installation and embedding of fiber optic piezometers are similar to those of osmometers. After the fiber optic piezometers are tested and qualified before on-site installation, they are wrapped with geotextiles and fine sand and gravel, and horizontally embedded in the pit. The embedding elevation needs to be accurately recorded during embedding. Then, it is backfilled with fine materials to the top of the pit. The instrument optical cable is sheathed with a PE pipe (along the trench) and horizontally pulled to the upstream dam slope, and then pulled along the upstream dam slope to the dam top observation room.

[0068] So far, relying on the systematic monitoring layout of flexible inclinometers and fiber optic piezometers, and cooperating with the ultra-wideband radar monitoring system to obtain the elevation values of the reference point in real time, a relatively perfect settlement monitoring technical scheme for the upstream rockfill area has been formed. This technical scheme can automatically read the data of all monitoring instruments, avoid the disadvantages of manual data collection after impoundment, and can realize monitoring automation.

[0069] The above embodiments are only the preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The protection scope of the present invention should be the technical solutions recorded in the claims, including equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. Settlement monitoring method for upstream rockfill area of high earth-rock dam, characterized in that: The settlement monitoring method includes the installation and embedding method of a flexible inclinometer, the installation and embedding method of an optical fiber pressure gauge, and the installation and embedding method of an ultra-wideband radar monitoring system; The flexible inclinometer is horizontally embedded and used to monitor the settlement distribution of the upstream rockfill along the water flow direction; The optical fiber pressure gauges are embedded in layers on the upstream dam slope and in the rockfill area to comprehensively monitor the settlement conditions of different parts and elevations of the upstream rockfill; The foundation of the ultra-wideband radar monitoring system mainly serves as the detection reference for the flexible inclinometer, and the settlement of this foundation is used to correct the measured values of each measuring point of the flexible inclinometer; The flexible inclinometer includes a casing, inside which there are a precision inclinometer and a coarse inclinometer. One end of the casing is provided with a connection end, one end of the connection end is provided with a connecting rod, one end of the connecting rod is provided with a universal joint, and the connection end is connected to the casing through a plurality of bolts; A coarse measurement device and a precision measurement wire are connected between two adjacent flexible inclinometers; The connection end includes an end body, on which there is a first cavity, and the precision measurement wire passes through the first cavity and is connected to two adjacent precision inclinometers; A connection head is provided on the connection end. The connection head includes a housing, one end of the housing is provided with an annular groove, one end of the annular groove is provided with an annular circular groove, and a through second cavity is provided in the middle of the housing; The coarse measurement device includes a coarse measurement wire with a spring-like structure. Multiple flexible steel wires are arranged outside the coarse measurement wire, and the multiple flexible steel wires are wound around and wrap the spring-like coarse measurement wire. The two ends of the flexible steel wires are provided with rolling balls, the two ends of the flexible steel wires abut against the annular groove, the rolling balls abut against the annular circular groove and slide, and the two ends of the coarse measurement wire respectively pass through the adjacent second cavities and are connected to two adjacent coarse inclinometers. The redundant parts at the two ends of the coarse measurement wire are wound inside the casing; The coarse measurement wire includes an electric core at the center, an insulating layer is provided outside the electric core, and a waterproof layer is provided outside the insulating layer; The precision inclinometer is used to measure small displacements; The coarse inclinometer is used to measure large displacements. When the precision measurement wire breaks, the spring-like coarse measurement wire elongates to roughly measure the settlement of the dam.

2. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 1, characterized in that: Steps of the installation and embedding method of the flexible inclinometer: S1. At 2 / 3 height of the dam monitoring cross-section, mechanically excavate a horizontal groove from the upstream rockfill area to the upstream transition layer; S2. Level the groove bed, then backfill fine materials from the bottom of the groove and mechanically roll and level; S3. Embed a precast concrete pedestal in the upstream transition material area, pre-embed a lifting ring on the side of the pedestal, fixedly connect the flexible inclinometer to the lifting ring with a movable hinge joint, and set a protective cover at the connection; S4. The upstream rockfill area is constructed by sectional and elevation-by-elevation filling. The flexible inclinometer is installed and embedded section by section, and the head and tail of each section of the flexible inclinometer are connected with movable hinge joints; S5. After installation, carry out relevant performance inspection tests on the instrument. After passing the inspection and testing, backfill the groove.

3. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 2 is characterized in that: at In S4, the installation and embedding of the flexible inclinometer are protected by a flexible PE pipe. The protection pipes for each section of the flexible inclinometer are integral pipes, and a PE pipe is sleeved outside the connection head of each flexible inclinometer for protection.

4. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 3, characterized in that: In S5, the groove is backfilled with fine materials with a particle size of more than 5 cm removed, and the groove is backfilled in layers of 20 cm each layer. Each layer is compacted by a vibrating rammer; When the filling surface is 1 m higher than the instrument embedding elevation, resume the normal filling of the dam.

5. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 1, wherein: Steps of the installation and embedding method of the optical fiber pressure gauge: A1. Install optical fiber pressure gauges at 3 typical elevations in the upstream rockfill area; After passing the test inspection before on-site installation, the fiber optic pressure gauge is wrapped with geotextile and fine sand and gravel, and horizontally buried in the pit. The elevation of the burial should be accurately recorded during the burial. Then, it is backfilled with fine materials to the top of the pit. The instrument optical cable is sleeved with a PE pipe and horizontally towed along the trench to the upstream dam slope, and then towed along the upstream dam slope to the dam top observation room.

6. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 1, wherein: Steps of the installation and burial method of the ultra-wideband radar monitoring system: B1. A steel plate is buried at the concrete base. The steel plate is fixed by expansion bolts, and a galvanized steel pipe is welded to the steel plate. The steel pipe is vertically extended with the filling of the rockfill. B2. The length of the steel pipe is detailedly recorded each time it is extended. An ultra-wideband radar monitoring point is installed at the pipe orifice to obtain the accurate elevation of the pipe orifice in real time, and the foundation elevation is calculated through the length of the steel pipe.

7. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 6, characterized in that: In B2, if the ultra-wideband radar monitoring system does not have the operating conditions, a fixed prism can be used instead, and the elevation of the pipe orifice is measured by a total station.

8. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 1, characterized in that: The basic principle of the flexible inclinometer is to detect the gravity field of each part, calculate the bending angle θ between each section of the axis, and use the calculated bending angle and the known length L of each section of the axis to determine the deformation Δχ of each section of the SAA, that is, Δχ = θ • L, and then sum up each section arithmetically ∑Δχ to obtain the deformation amount χ at any length from the fixed end point.

9. The settlement monitoring method for the upstream rockfill area of a high earth-rock dam according to claim 1, characterized in that: The principle of the fiber optic pressure gauge for monitoring settlement is to first accurately measure its installation elevation H1 (m), record the stable water level H2 (m) of the upstream rockfill after impoundment, and obtain the actual elevation H3 = H2 - h * 100 of the fiber optic pressure gauge after impoundment by reading the reading h (MPa) of the fiber optic pressure gauge, and then obtain the settlement amount H at the location of the fiber optic pressure gauge = H1 - H3.

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