Storage yard karst cave treatment method

Abstract

The invention provides a storage yard karst cave treatment method, which comprises the following steps of: geological exploration: establishing a karst cave spatial form model through drilling, and determining the flow direction and the supply source of underground water by utilizing a water level fluctuation test; accurately controlling blasting: adopting a millisecond millisecond blasting technology, ensuring that the explosive load of a single hole does not exceed 0.3 kg, ensuring that the flatness of the top of the hole is within a range of + / -15cm, and controlling the blasting vibration not to exceed 0.8 cm / s at the same time; a three-layer composite structure is used for backfilling, the lower layer is a boulder supporting layer, the middle layer is a gravel and rock ballast transition layer, and the upper layer is a reinforced concrete slab sealing layer. The safety of karst cave treatment is improved, especially for karst cave treatment needing to bear pressure, the stability of the cavern is effectively guaranteed, and collapse safety accidents are prevented; and the reliability of the treated cavern is ensured through the backfilling of the composite structure and the structure of the air guide device.

Description

Technical Field

[0001] The invention belongs to the technical field of karst cave treatment and relates to a method for treating a karst cave in a storage yard. Background Art

[0002] The treatment of underground caves generally adopts the full-filling method and the half-filling method. The principle of the full-filling cave treatment is to use high-pressure grouting to squeeze, hydrate, replace and other physical and chemical fillings to seal the karst seams and cut off the water source, and transform the fillings into a stone body with a certain strength. The half-filling method and the unfilled cave treatment generally adopt the method of blowing sand and stone (particle size 5-20mm) + grouting. For unfilled and half-filled caves with a depth greater than 2m, sand blowing is used first, and then grouting reinforcement is used. Grouting can be used to fill unfilled and half-filled caves of 2m and below.

[0003] Traditional cave treatment methods have the following problems: Failure to fully consider the characteristics of groundwater flow fields, resulting in leakage risks after treatment; The lack of systematic structural design makes it impossible to simultaneously meet the requirements of bearing capacity, impermeability and air permeability. Summary of the invention

[0004] The purpose of the present invention is to provide a method for treating a storage yard cave in view of the defects of the prior art, so as to solve the problems of the prior art.

[0005] In a first aspect, the present invention provides a method for treating a storage karst cave, comprising the following steps: Geological exploration: Establish a spatial morphological model of the cave through drilling, and use water level fluctuation tests to determine the direction of groundwater flow and the source of recharge; Precisely controlled blasting: using millisecond differential blasting technology, the charge per hole does not exceed 0.3kg, ensuring that the flatness of the cave top is within the range of ±15cm, and at the same time controlling the blasting vibration to no more than 0.8cm / s; Composite structure backfill: A three-layer composite structure is used for backfill, in which the lower layer is a large stone support layer, the middle layer is a transition layer of crushed stone and slag, and the upper layer is a reinforced concrete slab sealing layer.

[0006] Preferably, in the geological exploration stage, the following specific operation steps are also included: Drilling sampling: Select representative locations for drilling, cover the entire cave range in depth, set up detection holes at predetermined intervals, and obtain core samples at different depths; Data analysis and modeling: Analyze the collected data and use 3D Geographic Information System (GIS) software to generate accurate spatial morphology models; Water level fluctuation test: By periodically changing the water level in the detection hole and recording the water level change rate and recovery time, the groundwater flow direction and its recharge source are calculated using the principles of fluid mechanics.

[0007] Preferably, the water level fluctuation test includes: using a submersible pump to pump groundwater in the cave, monitoring the rate of water level drop during the pumping process, monitoring the rate of water level rise after a predetermined pumping time, and simultaneously querying the historical hydrological information of the cave, predicting future water level trends based on historical data and test data, thereby determining the diameter of the lower block stones of the composite structure.

[0008] Preferably, a ventilation pipe with a diameter of 200 mm is embedded in the lower layer, the opening rate is 15%, and the outside is wrapped with geotextile to prevent clogging by fine particles. The ventilation pipe passes through the composite structure and is connected to the atmosphere.

[0009] Preferably, the compressive strength of the lower layer is not less than 80 MPa, the compaction degree of the middle layer is not less than 95%, the reinforcement ratio of the upper layer is not less than 0.8%, and the overlap length of the steel bars and the bedrock is not less than 1 m.

[0010] Preferably, crushed stone and block stone are backfilled in alternate layers, and before backfilling, a geotextile is laid on the top surface of the block stone layer to separate the block stone from the crushed stone.

[0011] Preferably, after the cave treatment is completed, a drilling detection step is also included: drilling detection is performed at no less than six holes in the reinforced concrete slab sealing layer according to the maximum backfill depth to detect whether there is an overhead phenomenon.

[0012] A second aspect of the present invention provides a karst cave structure, which is formed by processing using any of the above-mentioned methods for processing karst caves in storage yards.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a method for treating a storage karst cave, which improves the safety of treating a karst cave, especially for treating a karst cave that needs to be pressurized, effectively ensuring the stability of the cave and preventing collapse accidents; the reliability of the treated cave is ensured by the composite structure backfill and the structure of the gas guide device.

[0014] 2. This invention realizes highly specialized and refined management of cave treatment by comprehensively using advanced exploration methods, scientific and reasonable precipitation strategies, precisely controlled blasting technology and meticulous backfilling measures. This method can not only effectively solve the cave problem, but also protect the surrounding environment to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of the cave after treatment according to the present invention.

[0016] Figure 2This is a state diagram before cave treatment in one embodiment of the present invention.

[0017] Figure 3 This is a schematic diagram of the backfill gravel state in an embodiment of the present invention.

[0018] Figure 4 It is a schematic diagram of the state of pouring the sealing layer of the reinforced concrete slab in an embodiment of the present invention.

[0019] In the above drawings: 1. Large stone support layer; 2. Crushed stone and slag transition layer; 3. Reinforced concrete slab sealing layer; 4. Ventilation pipe; 5. Geotextile. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific embodiments. However, it should be understood that the drawings are only used for exemplary descriptions and cannot be understood as limitations on this patent; in order to better illustrate this embodiment, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted; the positional relationship described in the drawings is only used for exemplary descriptions and cannot be understood as limitations on this patent.

[0021] The core of millisecond differential blasting is to use specially designed millisecond delay detonators (also called electronic detonators or non-electric detonators), which can detonate the charges in sequence within a very short time interval. Usually, this time interval can be set to range from a few milliseconds to tens of milliseconds. In this way, the explosions between adjacent blast holes will not occur at the same time, but in a predetermined order, which can effectively disperse the explosion energy, reduce the intensity of the shock wave generated by a single explosion, and reduce the overall blasting vibration. The principle of this blasting technology is well known in the construction field, so in the description of the present invention, the specific operation of millisecond differential blasting will not be repeated.

[0022] As an embodiment of the present invention, refer to Figure 1 This embodiment provides a method for treating a storage karst cave, comprising the following steps: Geological exploration: By drilling to establish a spatial morphological model of the cave, and by taking samples through drilling and using 3D Geographic Information System (GIS) software to generate the spatial morphological model, we can understand the internal structure and boundary conditions of the cave very accurately, which provides a solid foundation for subsequent blasting design and backfilling. Then, we use the water level fluctuation test to determine the flow direction and recharge source of groundwater, which not only helps to determine the flow direction and recharge source of groundwater, but also can predict future water level trends based on historical data, which is crucial for the design of dynamic precipitation systems, ensuring the effectiveness of precipitation systems and being able to flexibly adjust strategies according to changes in groundwater. Precisely controlled blasting: using millisecond differential blasting technology, the charge per hole does not exceed 0.3kg, ensuring that the flatness of the cave top is within the range of ±15cm, and at the same time controlling the blasting vibration to no more than 0.8cm / s; Composite structure backfill: A three-layer composite structure is used for backfill, in which the lower layer is a large stone support layer 1, the middle layer is a crushed stone and slag transition layer 2, and the upper layer is a reinforced concrete slab sealing layer 3. The backfill compressive strength of the large stone support layer 1 is not less than 80MPa, the compaction degree of the middle crushed stone and slag transition layer 2 is not less than 95%, the reinforcement ratio of the upper reinforced concrete slab sealing layer is not less than 0.8%, and the overlap length of the steel bars and the bedrock is not less than 1m.

[0023] In some preferred embodiments, during the geological exploration stage, the following specific operation steps are also included: Drilling sampling: Select representative locations for drilling, cover the entire cave range in depth, set up detection holes at predetermined intervals, and obtain core samples at different depths; Data analysis and modeling: Analyze the collected data and use 3D Geographic Information System (GIS) software to generate accurate spatial morphology models; Water level fluctuation test: By periodically changing the water level in the detection hole and recording the water level change rate and recovery time, the groundwater flow direction and its recharge source are calculated using the principles of fluid mechanics.

[0024] Specifically, the water level fluctuation test includes: using a submersible pump to pump groundwater in the cave, monitoring the water level drop rate during the pumping process, monitoring the water level rise rate after a predetermined pumping time, and querying the historical hydrological information of the cave at the same time, predicting future water level trends based on historical data and test data, thereby determining the diameter of the lower block stones of the composite structure.

[0025] In some preferred embodiments, in order to maintain good ventilation and avoid pressure increase caused by water accumulation, a ventilation pipe 4 with a diameter of 200 mm is embedded in the lower layer of this embodiment. The ventilation pipe is a galvanized steel pipe with an opening rate of 15%. The outside is wrapped with geotextile to prevent clogging by fine particles. The ventilation pipe passes through the composite structure and is connected to the atmosphere.

[0026] In some preferred embodiments, in order to improve the compaction effect and enhance the stability of the overall structure, the crushed stone and the block stone are backfilled in an alternate layered manner in this embodiment. Before backfilling, a geotextile 5 is laid on the top surface of the block stone layer to separate the block stone and the crushed stone.

[0027] In some preferred embodiments, after the treatment of the karst caves is completed, a drilling inspection step is further included: drilling inspection is performed at no less than six holes in the closed layer of the reinforced concrete slab according to the maximum backfill depth to detect whether there is an overhead phenomenon. After the treatment of the karst caves is completed, drilling inspection is performed, especially drilling inspection is performed at no less than six holes in the closed layer of the reinforced concrete slab according to the maximum backfill depth, which can effectively check whether there is an overhead phenomenon and ensure that the project quality meets the expected standards.

[0028] As another preferred embodiment of the present invention, this embodiment provides a cave structure, which is processed by the storage yard cave processing method described in any of the above embodiments.

[0029] Take a centralized phosphogypsum depot as an example. Figure 1 As shown in the figure, during the construction of a centralized phosphogypsum storage facility, a natural cave was discovered at the bottom of the storage facility. The construction process included: cave survey → water level monitoring → plan formulation → cave entrance blasting and slag removal → stone blocking → ventilation pipe installation → backfilling in layers with stones and crushed stones → capping with reinforced concrete slabs.

[0030] Through in-tunnel survey, Figure 2 As shown, the depth of the cave is about 21.7 meters, the length of the cave entrance is about 5.4 meters, the widest part is about 3.5 meters, and the narrowest part is about 1.4 meters. After determining the specifications of the cave, the spatial morphology model of the cave is established.

[0031] Water level fluctuation test: A submersible pump of model 100WQ-80-32-15 was used for pumping monitoring. The pumping pipe diameter was 100mm, the pumping flow rate was 80m³ / h, the pumping head was 32m, and the power was 15kw. The water level monitoring results are shown in the following table:

[0032] Customized treatment solutions: Remove loose, inverted and sharp rocks from the cave entrance and walls, follow the cave to the place where the passage is obviously narrowed, and set up large rocks to block it; Bury the D200 ventilation pipe and fix it to the cave wall with a pipe clamp. Extend it out of the ground and then extend it along the ground to the hillside. The ventilation pipe should be protected to prevent blockage and damage. The ventilation pipes are connected by welding; Requirements for ventilation pipe drilling: The part below the ground is drilled in a plum blossom shape with a hole diameter of 10mm and wrapped with geotextile; The cave is filled with rocks to a height of 135m, with a particle size of 20-40cm, and then filled with well-graded crushed stones, such as Figure 3 As shown, the crushed stone particle size is 20-40mm, and 400g / m 2 The geotextiles are separated, and the backfill is mechanically backfilled in layers and compacted by a 26t vibrating roller; Backfill requirements above 135m: first backfill 1m thick 20~40mm crushed stone, then backfill 1m thick block stone slag mixture, and finally backfill 20~40mm crushed stone to the designed elevation; Filling requirements: Ensure that all gaps in the hole are completely filled, with no gaps of 50 cm in size; the porosity of the block stone is less than 25%, and the heavy-duty dynamic probing result of the gravel is greater than 150kpa.

[0033] After the gravel is filled to the surface, it needs to be backfilled along the slope because the surrounding terrain is uneven. Figure 4 As shown, then lay a 15cm thick C20 concrete cushion layer, and finally cast the reinforced concrete slab. The concrete slab needs to overlap with the intact rock by 1m. The concrete slab construction needs to have north-south construction joints, and the construction joint spacing is 12-15m.

[0034] Reinforcement requirements for reinforced concrete slabs: double-layer bidirectional reinforcement with a spacing of 200mm; set hooks with a spacing of 400; set horse stool bars with a spacing of 600mm.

[0035] During blasting, the stability of the cavern is taken into consideration to prevent the cavern from collapsing. The precise blasting steps are as follows: 5 millisecond difference blastings, single hole charge ≤ 0.3kg, vibration controlled ≤ 0.8cm / s; after each blasting, the slag is cleaned and the next blasting is designed.

[0036] After the construction was completed, drilling inspection was carried out on 6 inspection holes with a depth of 18m, which confirmed that there was no overhead phenomenon and the cave treatment was completed.

[0037] The present invention adopts millisecond differential blasting technology to disperse the explosive energy, which not only ensures the flatness of the cave roof, but also controls the blasting vibration at a low level, greatly reducing the potential harm to the surrounding environment and buildings. The three-layer composite structure design forms a solid overall structure with good drainage performance, which enhances the stability of the backfill area.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for treating a storage yard cave, characterized in that: The following steps are involved: Geological exploration: Establish a spatial morphological model of the cave through drilling, and use water level fluctuation tests to determine the direction of groundwater flow and the source of recharge; Precisely controlled blasting: using millisecond differential blasting technology, the charge per hole does not exceed 0.3kg, ensuring that the flatness of the cave top is within the range of ±15cm, and at the same time controlling the blasting vibration to no more than 0.8cm / s; Composite structure backfill: A three-layer composite structure is used for backfill, in which the lower layer is a large stone support layer, the middle layer is a transition layer of crushed stone and slag, and the upper layer is a reinforced concrete slab sealing layer.

2. A method for treating a storage karst cave according to claim 1, characterized in that: In the geological exploration stage, the following specific operation steps are also included: Drilling sampling: Select representative locations for drilling, cover the entire cave range in depth, set up detection holes at predetermined intervals, and obtain core samples at different depths; Data analysis and modeling: Analyze the collected data and use 3D Geographic Information System (GIS) software to generate accurate spatial morphology models; Water level fluctuation test: By periodically changing the water level in the detection hole and recording the water level change rate and recovery time, the groundwater flow direction and its recharge source are calculated using the principles of fluid mechanics.

3. A method for treating a storage karst cave according to claim 2, characterized in that: The water level fluctuation test includes: using a submersible pump to pump groundwater in the cave, monitoring the water level drop rate during the pumping process, monitoring the water level rise rate after a predetermined pumping time, and querying the historical hydrological information of the cave at the same time, predicting the future water level trend based on historical data and test data, so as to determine the diameter of the lower block of the composite structure.

4. A method for treating a storage karst cave according to claim 1, characterized in that: A ventilation pipe with a diameter of 200 mm is embedded in the lower layer, with an opening rate of 15%. The outside is wrapped with geotextile to prevent clogging by fine particles. The ventilation pipe passes through the composite structure and is connected to the atmosphere.

5. A method for treating a storage karst cave according to claim 1, characterized in that: The compressive strength of the lower layer shall not be less than 80MPa, the compaction degree of the middle layer shall not be less than 95%, the reinforcement ratio of the upper layer shall not be less than 0.8%, and the lap length between the steel bars and the bedrock shall not be less than 1m.

6. A method for treating a storage karst cave according to claim 1, characterized in that: The crushed stone and block stone are backfilled in layers at intervals. Before backfilling, geotextile is laid on the top of the block stone layer to separate the block stone from the crushed stone.

7. The method according to claim 1, characterized in that After the cave treatment is completed, the step of drilling detection is also included: drilling detection is carried out in no less than six holes in the closed layer of the reinforced concrete slab according to the maximum backfill depth to detect whether there is any overhead phenomenon.

8. A karst cave structure, characterized in that: The method is processed by any one of claims 1 to 7.

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