Cold region slope anti-freezing drainage drilling device and anti-freezing method

Abstract

The invention relates to a cold region slope anti-freezing drainage drilling device and an anti-freezing method.The cold region slope anti-freezing drainage drilling device comprises an anti-radiation layer, a heat preservation layer, a freezing and thawing layer, an electric tracing band, a drainage floral tube, an osmometer, a temperature sensor, a water stop band and a control system, the drainage tube or a plastic blind ditch is arranged in a drainage drill hole, and the heat preservation layer is arranged on the lower surface of the anti-radiation layer; the electric tracing band is arranged between the lower surface of the heat preservation layer and the outer surface of the drainage pipe, the water stop band is arranged on the interface of the freeze-thaw layer section drainage pipe and the drainage section drainage pipe, the osmometer is arranged on the drainage section drainage pipe or the outer surface of the tail end of the plastic blind ditch, and the temperature sensor is arranged on the outer surface of the heat preservation layer and the lower surface of the anti-radiation layer. Signal lines of the osmometer and the temperature sensor and a power supply line of the electric tracing band are connected to a control system. According to the method, the drainage holes are prevented from freezing in winter, the drainage holes are prevented from losing efficacy due to freezing, the monitoring and early warning threshold value is determined according to the sensitivity analysis of the underground water pressure on the slope stability state, and landslide early warning is carried out.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed engineering, and in particular to a cold region slope antifreeze and drainage drilling device and an antifreeze method. Background Art

[0002] In slope engineering, the pore water pressure caused by groundwater is an important cause of slope instability. Therefore, it is often necessary to drain the groundwater in engineering to improve the stability of the slope, and the inclined drainage holes are a commonly used drainage measure. For water-rich slopes in cold regions, due to seasonal freeze-thaw, the drainage holes of the slopes are often blocked by low-temperature freezing, resulting in failure of the drainage holes. Since the groundwater in the non-freeze-thaw zone inside the slope cannot be effectively discharged, the pore water pressure continues to rise, which may often cause frost heave deformation of the slope and even induce landslide disasters. Solving the internal groundwater drainage and real-time monitoring and early warning of water pressure during the freezing period of water-rich slopes in cold regions is an important measure to achieve safe operation of slopes in cold regions.

[0003] Defects and shortcomings of the existing technology:

[0004] (1) Conventional inclined drainage boreholes freeze at the borehole opening in cold regions in winter, and the groundwater inside cannot be discharged;

[0005] (2) Conventional inclined drainage boreholes lack insulation and heating measures and are prone to failure in winter in cold regions.

[0006] (3) Conventional inclined drainage drilling cannot provide timely feedback and control of antifreeze measures based on temperature monitoring;

[0007] (4) Conventional inclined drainage drilling holes do not have internal pore water pressure monitoring in the slope. When the hole mouth freezes and fails, the internal water pressure increases and cannot be monitored and warned in time. Summary of the invention

[0008] The present invention provides a freezing and dewatering drilling device and a freezing and defreezing method for slopes in cold regions. Different dewatering drilling structures are designed to prevent the dewatering holes in the frozen-thaw layer section from freezing in winter. Electric heating, thermal insulation layers and anti-radiation layer insulation measures are adopted to effectively keep the temperature of the dewatering holes in the frozen-thaw layer section above 0°C to prevent freezing from causing the dewatering drilling holes to fail. The temperature of the frozen-thaw layer section is monitored in real time, and the heating power is regulated and controlled in time to achieve the economy of heating. The pore water pressure of the internal dewatering section is monitored in real time, and the monitoring and early warning threshold is determined according to the sensitivity analysis of the groundwater pressure to the slope stability state to carry out landslide early warning.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A cold-region slope antifreeze drainage drilling device comprises an anti-radiation layer, an insulation layer, an electric heating tape, a drainage pipe, a piezometer, a temperature sensor, a water stop and a control system. The drainage borehole is arranged through the slope surface, the freeze-thaw layer and the sliding zone. The drainage pipe is arranged in the drainage borehole. The anti-radiation layer is arranged on the outer surface of the insulation layer in the freeze-thaw layer section. The insulation layer is arranged on the lower surface of the anti-radiation layer. The electric heating tape is arranged between the lower surface of the insulation layer and the outer surface of the drainage pipe. The water stop is arranged at the interface between the freeze-thaw layer section drainage pipe and the drainage section drainage pipe. The piezometer is arranged on the outer surface of the drainage pipe end of the drainage section. The temperature sensor is arranged on the lower surface of the anti-radiation layer on the outer surface of the insulation layer. The signal lines of the piezometer and the temperature sensor and the power supply lines of the electric heating tape are connected to the control system.

[0011] Furthermore, the spacing between the drainage boreholes is 3m to 20m, and the inclination angle is 5° to 15°.

[0012] Furthermore, the control system includes a data acquisition unit DTU, an AC power supply, an audible and visual alarm device, and a control center. The IO signal end of the data acquisition unit DTU is connected to the signal lines of the osmometer, the temperature sensor, and the audible and visual alarm device. The AC power supply is connected to the power supply ends of the osmometer and the temperature sensor. The data acquisition unit DTU is connected to the control center via a communication cable or GPRS.

[0013] Furthermore, the insulation layer is made of rubber-plastic insulation cotton with a thickness of 25 mm to 50 mm, and the gap between the insulation layer and the drainage drilled holes is filled with cement or foamed glue.

[0014] Furthermore, the drainage pipe includes a freeze-thaw layer section and a drainage section, with a pipe diameter of 50mm to 150mm. The freeze-thaw layer section drainage pipe adopts a PVC pipe or a steel pipe without water-permeable holes on the surface. The drainage pipe of the drainage section adopts a PVC pipe, a steel pipe or a plastic blind ditch with water-permeable holes, and is wrapped with geotextile on the outside.

[0015] A method for antifreezing a slope antifreeze drainage borehole in cold regions, comprising the following steps:

[0016] S1. Determine the thickness T of the freeze-thaw layer based on the local frozen soil thickness or engineering survey data;

[0017] S2, length of freeze-thaw layer:

[0018]

[0019] Wherein, T is the thickness of the freeze-thaw layer; a is the slope angle; F1 is the safety factor, which is 1.2 to 1.5;

[0020] The diameter of the hole drilled in the freeze-thaw layer: D = 2 (r1 + t1 + t2 + t3 + t4) (2)

[0021] Among them, D is the diameter of the drill hole in the freeze-thaw layer; r1 is the radius of the drainage pipe or plastic blind ditch; t1 is the thickness of the heating tape; t2 is the thickness of the anti-radiation layer; t3 is the thickness of the insulation layer; t4 is the installation surplus thickness, which is 5mm to 10mm;

[0022] S3. Drill holes in the freeze-thaw layer section to set up cold area slope antifreeze and drainage drilling devices for antifreeze;

[0023] S4, determine the drainage section length L2 of the drainage borehole, and penetrate the slope sliding zone determined by the survey or stability analysis;

[0024] S5. The design of drainage drilling holes shall meet the requirements of sliding body stability, and the spacing shall be 3m to 20m;

[0025] S6. A temperature sensor is installed in the freeze-thaw layer section of the drainage borehole for temperature monitoring. When the temperature monitoring result of the freeze-thaw layer section is ≤0℃, or the weather forecast shows that the temperature will drop to 0℃ or below, the control system automatically starts the electric heating belt;

[0026] S7. A piezometer is used to monitor water pressure in the drainage section, and a water pressure warning threshold is set. When the water pressure reaches the corresponding warning value, the monitoring system automatically issues a warning message.

[0027] Furthermore, the water pressure warning threshold is determined based on a sensitivity analysis of the impact of water pressure on slope stability, including four levels: blue, yellow, orange and red, and the corresponding stability states are: basically stable: design safety factor > stability factor ≥ 1.05, under-stability: 1.05 > stability factor ≥ 1.0, critical state: stability coefficient = 1.0, and unstable: 1.0 > stability coefficient.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1) According to the thickness of the local freeze-thaw layer, the freeze-thaw layer section and the drainage section are divided into different drainage drilling structures to prevent the freeze-thaw layer section from freezing in winter and save the length of the freeze-thaw layer section;

[0030] 2) Adopt electric heating, anti-radiation layer and insulation layer insulation measures to effectively keep the temperature of the drainage holes in the frozen-thaw layer above 0°C to avoid freezing and causing the drainage holes to fail;

[0031] 3) Monitor the temperature of the freeze-thaw layer in real time, and automatically feedback and adjust the power of electric heating in time according to the monitoring results to achieve economic heating;

[0032] 4) Monitor the pore water pressure in the internal non-freeze-thaw layer in real time, and issue landslide warnings based on the water pressure warning threshold determined by sensitivity analysis of the impact of water pressure on slope stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of groundwater drainage on slopes in cold regions according to the present invention.

[0034] Figure 2 It is a schematic diagram of the structure of the device of the present invention.

[0035] Figure 3 It is a schematic diagram of the AA cross-section of the device structure of the present invention.

[0036] Figure 4 It is a schematic cross-sectional view of the device structure BB of the present invention.

[0037] In the figure: 1. Groundwater 2. Upward-inclined borehole 3. Slope surface 4. Freeze-thaw layer 5. Anti-radiation layer 6. Insulation layer 7. Electric heating tape 8. Drain pipe 9. Osmometer 10. Temperature sensor 11. Communication cable 12. Data acquisition unit DTU 13. AC power supply 14. Waterstop DETAILED DESCRIPTION

[0038] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings:

[0039] See Figure 1-2 , is a schematic diagram of the structure of the present invention. The present invention is a cold-region slope antifreeze drainage drilling device, comprising an anti-radiation layer 5, an insulation layer 6, an electric heating tape 7, a drainage pipe 8, a piezometer 9, a temperature sensor 10, a water stop 14 and a control system, wherein the drainage pipe 8 is arranged in the drainage borehole, and the anti-radiation layer 5 is arranged on the outer surface of the insulation layer 6 of the freeze-thaw layer 4, and an aluminum foil anti-radiation layer 5 is adopted; the insulation layer 6 is arranged on the lower surface of the anti-radiation layer 5, and the insulation layer 6 adopts rubber-plastic insulation cotton with a thickness of 25mm to 50mm, and the gap between the drainage borehole and the drainage borehole is filled with cement or foam; the electric heating tape 7 is arranged between the lower surface of the insulation layer 6 and the outer surface of the drainage pipe 8, and the drainage borehole is penetrated and arranged on the slope surface 3, the freeze-thaw layer 4 and the sliding zone; the drainage pipe 8 includes a freeze-thaw layer section and a drainage section drainage pipe 8, and the freeze-thaw layer section drainage pipe 8 is made of PVC pipe, steel pipe, etc., The pipe diameter is between 50mm and 150mm. The hole wall of the drainage pipe 8 in the drainage section is provided with permeable flower holes, and the outside is wrapped with a geotextile with good permeability. It can also be replaced by a plastic blind ditch product. The water stop strip 14 is arranged at the interface between the drainage pipe 8 in the freeze-thaw layer 4 and the drainage pipe 8 in the drainage section. The material is rubber or waterproof tape to prevent long-term erosion of the insulation material by seepage and cause a decrease in the insulation performance. The piezometer 9 is arranged on the outer surface of the drainage pipe 8 in the drainage section or the end of the plastic blind ditch, and the temperature sensor 10 is arranged on the lower surface of the anti-radiation layer 5 on the outer surface of the insulation layer 6. The temperature sensor 10 is buried, and the main parameters meet the following requirements: range: T1~+70℃, T1 is the local minimum winter temperature or the designed minimum temperature; the water pressure resistance is consistent with that of the piezometer 9, and the signal lines of the piezometer 9 and the temperature sensor 10 and the power supply line of the electric heating tape 7 are connected to the control system.

[0040] The spacing of the inclined boreholes 2, i.e. the drainage boreholes, is determined according to the permeability of the landslide body, and is 3m to 20m, or is determined by numerical calculation of seepage flow, and the inclination is 5° to 15°.

[0041] The control system includes a data acquisition unit DTU12, an AC power supply 13, an audible and visual alarm device and a control center. The IO output end of the data acquisition unit DTU12 is connected to the signal lines of the osmometer 9, the temperature sensor 10, the electric heating belt 7 and the audible and visual alarm device. The AC power supply 13 is connected to the power supply end of the osmometer 9 and the temperature sensor 10, and is powered by a universal 220V AC power supply. The power should be the total power of the heating device. The data acquisition unit DTU12 is connected to the control center via a communication cable 11 or GPRS.

[0042] A method for antifreezing a slope antifreeze drainage borehole in cold regions, comprising the following steps:

[0043] S1. There is seasonal freeze-thaw phenomenon on the slopes in cold regions. The thickness of the freeze-thaw layer 4 is T, which is determined based on the local frozen soil thickness or engineering survey data.

[0044] S2, length of 4 sections of freeze-thaw layer:

[0045]

[0046] Wherein, T is the thickness of the freeze-thaw layer 4;

[0047] a is the slope angle;

[0048] F1 is the safety factor, ranging from 1.2 to 1.5;

[0049] The diameter of the hole drilled in the 4th section of the freeze-thaw layer: D = 2 (r1 + t1 + t2 + t3 + t4) (4)

[0050] Where D is the diameter of the borehole in the 4th section of the freeze-thaw layer;

[0051] r1 is the radius of the drainage pipe 8 or the plastic blind ditch;

[0052] t1 is the thickness of the heating tape;

[0053] t2 is the thickness of the anti-radiation layer 5;

[0054] t3 is the thickness of the insulation layer 6;

[0055] t4 is the excess thickness for installation, ranging from 5mm to 10mm.

[0056] S3. A cold area slope antifreeze and drainage drilling device is set up in the 4th section of the freeze-thaw layer for antifreeze. The drainage pipe 8 in the 4th section of the freeze-thaw layer is not provided with flower holes to prevent water seepage from eroding the insulation layer 6.

[0057] S4. Determine the drainage section length L2 of the drainage borehole, which should penetrate the slope sliding zone determined by investigation or stability analysis.

[0058] S5. The spacing of inclined drilling holes, i.e. drainage drilling holes, is determined according to the permeability of the landslide body, and is 3m to 20m, or determined by numerical seepage calculation. The inclination is 5° to 15°. The design of drainage drilling holes should meet the requirements of sliding body stability. The stability calculation method of the landslide body is evaluated by the limit equilibrium method, strength reduction method, etc.

[0059] S6. A temperature sensor 10 is set at the 4th section of the freeze-thaw layer for temperature monitoring in the drainage borehole, and the monitoring data is collected and transmitted to the control center. When the temperature monitoring result of the 4th section of the freeze-thaw layer is ≤0°C, or the weather forecast shows that the temperature will drop to 0°C or below, the control system automatically starts the electric heating cable 7;

[0060] The amount of heat that the electric heating system should provide: Q = Q1 + Q2 + Q3 + Q4 (5)

[0061] Wherein, Q1 is the heat required to store the temperature of the insulation layer 6;

[0062] Q2 is the heat used to heat the ice and store heat;

[0063] Q3 is the latent heat of phase change absorbed during ice melting;

[0064] Q4 is the heat transferred by convection;

[0065] Q1=ρ1V1c1(T1-T0) (6)

[0066] Q2=ρ2V2(c w T0-c s T2) (7)

[0067] Q3=ρ2V2h f (8)

[0068] Q4=Ah k (T2-T0) (9)

[0069] Wherein, ρ1 is the density of the insulation layer 6, kg / m;

[0070] ρ2 is the density of ice, kg / m;

[0071] V1 is the volume of the insulation layer 6 per unit length, V = 0.5π (r1 + t1 + t2) 2 (r1+t1+t2+t3);

[0072] V2 is the ice volume per unit length of the drainage pipe 8, V = 0.5πr1 2 n, n is generally taken as 1, and when it is a plastic blind ditch, its porosity is taken;

[0073] A is the contact area between the drain pipe 8 and the ice, m, A=0.5π(r1+t1+t2) 2 ;

[0074] c1 is the specific heat capacity of the insulation layer 6, kJ / (kg·K);

[0075] T0 is the initial ambient temperature, °C;

[0076] T1 is the temperature of the insulation layer 6 after being heated, °C;

[0077] T2 is the temperature at which ice melts into water, °C;

[0078] x is the melting range of ice, m;

[0079] c s is the specific heat capacity of ice, kJ / (kg·K);

[0080] c w is the specific heat capacity of water, kJ / (kg·K);

[0081] h f is the heat of fusion of ice, take 334 kJ / (kg·K);

[0082] h k The convection heat transfer coefficient is 500W / (m·℃);

[0083] Required length L of electric heating cable 7:

[0084] Among them, Q m It is the heating power per unit length of the electric heating cable 7.

[0085] S7, water pressure monitoring is performed using osmometer 9 in the drainage section:

[0086] The measuring range of the piezometer 9 should meet the maximum pressure requirement considering the water pressure amplitude:

[0087] L SY ≥(H+H W )*g*F S (11)

[0088] Among them, L SY It is an osmometer with 9 ranges;

[0089] H is the natural water level depth;

[0090] H W is the expected maximum fluctuation of water level;

[0091] g is the acceleration due to gravity;

[0092] FS is the safety factor, which is 1.25 to 1.5;

[0093] Water pressure monitoring and early warning: (1) The pore water pressure inside the slope is monitored in real time by a piezometer 9. The water pressure will increase when the following situations occur: ① The drainage holes in the frozen-thaw layer 4 are blocked and fail; ② The groundwater 1 increases due to rainfall, aquifer recharge, etc.;

[0094] (2) When the monitored pore water pressure value is greater than the preset warning threshold, the monitoring center automatically issues a warning message;

[0095] (4) The warning threshold is determined by water pressure sensitivity analysis based on the slope stability calculation model. The calculation method can be the Bishop method of limit equilibrium method, the Morgenstern-Price method, the plane or wedge limit equilibrium method, the numerical back analysis method, etc.

[0096] (5) The water pressure warning threshold is divided into four levels: blue, yellow, orange and red according to the sensitivity analysis results. The corresponding stability states are: basically stable (design safety factor > stability factor ≥ 1.05), understable (1.05 > stability factor ≥ 1.0), critical state (stability coefficient = 1.0), and unstable (1.0 > stability coefficient).

[0097] The above embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the above embodiments. The methods used in the above embodiments are conventional methods unless otherwise specified.

Claims

1. A cold area slope antifreeze drainage drilling device, characterized in that: It includes an anti-radiation layer, an insulation layer, an electric heating tape, a drainage pipe, a piezometer, a temperature sensor, a waterstop and a control system. The drainage borehole is arranged through the slope surface, the freeze-thaw layer and the sliding zone. The drainage pipe is arranged in the drainage borehole. The anti-radiation layer is arranged on the outer surface of the insulation layer in the freeze-thaw layer section. The insulation layer is arranged on the lower surface of the anti-radiation layer. The electric heating tape is arranged between the lower surface of the insulation layer and the outer surface of the drainage pipe. The waterstop is arranged at the interface between the drainage pipe in the freeze-thaw layer section and the drainage pipe in the drainage section. The piezometer is arranged on the outer surface of the end of the drainage pipe in the drainage section. The temperature sensor is arranged on the lower surface of the anti-radiation layer on the outer surface of the insulation layer. The signal lines of the piezometer and the temperature sensor and the power supply lines of the electric heating tape are connected to the control system.

2. A cold region slope antifreeze drainage drilling device according to claim 1, characterized in that: The spacing between the drainage boreholes is 3m to 20m, and the inclination angle is 5° to 15°.

3. The cold region slope antifreeze and drainage drilling device according to claim 1, characterized in that: The control system includes a data acquisition unit DTU, an AC power supply, an audible and visual alarm device, and a control center. The IO signal end of the data acquisition unit DTU is connected to the signal lines of the osmometer, the temperature sensor, and the audible and visual alarm device. The AC power supply is connected to the power supply ends of the osmometer and the temperature sensor. The data acquisition unit DTU is connected to the control center via a communication cable or GPRS.

4. The cold region slope antifreeze drainage drilling device according to claim 1, characterized in that: The insulation layer is made of rubber-plastic insulation cotton with a thickness of 25 mm to 50 mm, and the gap between the insulation layer and the drainage drill hole is filled with cement or foamed glue.

5. The cold region slope antifreeze and drainage drilling device according to claim 1, characterized in that: The drainage pipes include freeze-thaw layer section and drainage section drainage pipes with a pipe diameter of 50mm to 150mm. The freeze-thaw layer section drainage pipes are made of PVC pipes or steel pipes without water-permeable holes on the surface. The drainage section drainage pipes are made of PVC pipes, steel pipes or plastic blind ditches with water-permeable holes and are wrapped with geotextile on the outside.

6. The antifreeze method of the cold region slope antifreeze drainage drilling device according to any one of claim 1, characterized in that: The steps include: S1. Determine the thickness T of the freeze-thaw layer based on the local frozen soil thickness or engineering survey data; S2, length of freeze-thaw layer: Wherein, T is the thickness of the freeze-thaw layer; a is the slope angle; F1 is the safety factor, which is 1.2 to 1.5; The diameter of the hole drilled in the freeze-thaw layer: D = 2 (r1 + t1 + t2 + t3 + t4) (2) Among them, D is the diameter of the drill hole in the freeze-thaw layer; r1 is the radius of the drainage pipe or plastic blind ditch; t1 is the thickness of the heating tape; t2 is the thickness of the anti-radiation layer; t3 is the thickness of the insulation layer; t4 is the installation surplus thickness, which is 5mm to 10mm; S3. Drill holes in the freeze-thaw layer section to set up cold area slope antifreeze and drainage drilling devices for antifreeze; S4, determine the drainage section length L2 of the drainage borehole, and penetrate the slope sliding zone determined by the survey or stability analysis; S5. The design of drainage drilling holes shall meet the requirements of sliding body stability, and the spacing shall be 3m to 20m; S6. A temperature sensor is installed in the freeze-thaw layer section of the drainage borehole for temperature monitoring. When the temperature monitoring result of the freeze-thaw layer section is ≤0℃, or the weather forecast shows that the temperature will drop to 0℃ or below, the control system automatically starts the electric heating belt; S7. A piezometer is used to monitor water pressure in the drainage section, and a water pressure warning threshold is set. When the water pressure reaches the corresponding warning value, the monitoring system automatically issues a warning message.

7. A cold region slope antifreeze and drainage drilling antifreeze method according to claim 6, characterized in that: The water pressure warning threshold is determined based on a sensitivity analysis of the impact of water pressure on slope stability, and includes four levels: blue, yellow, orange and red. The corresponding stability states are: basic stability is when the design safety factor is greater than or equal to 1.05, understability is when 1.05 is greater than or equal to 1.0, critical state is when the stability coefficient is equal to or equal to 1.0, and instability is when 1.0 is greater than the stability coefficient.

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