Construction method of weak surrounding rock vertical shaft pilot shaft and concrete retaining wall structure

Abstract

The invention relates to a construction method of a weak surrounding rock vertical shaft pilot shaft and a concrete retaining wall structure. Relates to the technical field of building construction, and the method comprises the following steps: firstly, drilling a first vertical shaft guide hole by using a directional drilling machine, and performing first reverse drawing well completion by using a raise boring machine to form a first guide shaft; then, micro-expansion self-compacting concrete is adopted for backfilling, and a concrete column structure is formed; then, the directional drilling machine conducts second guide hole construction in the center of the first guide well backfill concrete, and it is ensured that a second guide hole and the first guide hole are concentric; and finally, the raise boring machine is used for conducting second-time reverse drawing well forming, a second pilot well is formed, and therefore the concrete retaining wall structure with the excellent supporting force is formed through two times of pilot well forming. The construction method effectively improves the pilot shaft construction precision, stability and safety, is suitable for complex geological conditions such as weak surrounding rock and has high construction efficiency and economic benefits.

Description

Technical Field

[0001] The invention relates to the technical field of building construction, and in particular to a construction method for a soft surrounding rock vertical shaft guide shaft and a concrete wall protection structure. Background Art

[0002] In the field of shaft excavation and support, the reverse shaft method is a relatively mature and widely used construction method. It has become the mainstream solution for shaft excavation and support due to its low construction difficulty, high slag removal efficiency, and strong construction safety. The basic process of this method is: first, a reverse shaft drilling rig is used to drill a hole from top to bottom in the shaft to form a pilot hole; then, through the pilot hole, a reaming drill bit is installed at the bottom of the shaft, and the reaming drill bit is used to reverse from bottom to top to form a pilot shaft; finally, the pilot shaft is used to complete the slag removal construction. Compared with the traditional shaft excavation method, the reverse shaft method has higher construction efficiency, more controllable construction period, lower construction cost and smaller construction safety risk.

[0003] However, despite the significant advantages of the reverse shaft method in shaft excavation, there are still certain technical difficulties in its construction process, especially in the slag removal process of the pilot shaft. The slag removal process of the pilot shaft usually encounters a large amount of slag from the upper excavation surface. These slags quickly fall into the pilot shaft under the action of gravity, which may cause certain impact and damage to the pilot shaft structure. During shaft construction, if the geological conditions are poor, such as the presence of unfavorable geological conditions such as broken zones or weak rock masses, or abundant groundwater, the gravity impact of slag may cause the stability of the pilot shaft to be damaged, or even cause the pilot shaft to collapse, and the risk of overall instability of the shaft will also increase.

[0004] In addition, the collapse of the pilot shaft will not only affect the slag removal effect, but may also cause serious collapse of the shaft, greatly increasing the safety hazards during construction. This unstable situation is particularly prominent under specific geological conditions, especially in complex geological areas such as weak rock and broken zones, where the safety hazards are more obvious. Therefore, in the implementation of the reverse well method, how to effectively prevent the collapse of the pilot shaft and ensure the structural stability of the entire shaft has become a technical problem that needs to be solved urgently. Summary of the invention

[0005] In order to improve the problem of landslides easily caused by the reverse shaft construction method in places with poor geological conditions, the present application provides a soft surrounding rock vertical shaft pilot shaft concrete wall protection structure and a construction method.

[0006] In the first aspect, the present application provides a construction method for a soft surrounding rock vertical shaft pilot shaft, which adopts the following technical solution: A construction method for a soft surrounding rock vertical shaft pilot shaft comprises the following steps: Step 1: Use a directional drill to drill vertically downward along the rock mass of the vertical shaft to be constructed to form a first vertical shaft guide hole, and at the same time confirm the accuracy of the first vertical shaft guide hole; Step 2: Use a raise drilling rig to perform the first reverse well drilling to form the first pilot well; Step 3: backfilling the bottom of the first pilot shaft with slag back pressure, and pouring backfill concrete from the bottom of the first pilot shaft to form a concrete column structure in the first pilot shaft; Step 4: Use a directional drill to perform a second pilot hole construction in the center of the concrete column structure backfilled in the first pilot shaft to form a second vertical shaft pilot hole, while ensuring that the second vertical shaft pilot hole is located in the center of the concrete column structure; Step 5: Use a reverse well drilling machine to perform a second reverse well pulling to form a second guide well with a diameter smaller than the first guide well. After the second guide well is drilled and formed, the concrete column structure between the first guide well and the second guide well serves as the concrete retaining wall of the vertical shaft guide well.

[0007] Preferably, the concrete used for backfilling is micro-expansive self-compacting concrete, which is backfilled after the first guide shaft is formed to form a dense concrete column structure.

[0008] Preferably, in the step 1, a directional drill is used to form the first shaft guide hole by drilling vertically downward for more than 150 m along the ground to be constructed.

[0009] Preferably, in step five, the diameter of the first pilot shaft is 60 cm to 80 cm larger than the diameter of the second pilot shaft.

[0010] Preferably, when there is groundwater at the construction site, a drainage channel should be provided at the bottom wall of the first pilot shaft at an angle of 30° downward and outward before backfilling the concrete to prevent the groundwater from affecting the forming of the backfill concrete.

[0011] Preferably, in step 4, before the second guide hole construction, the drilling speed, correction amount and correction angle of the second guide hole construction are determined through experiments to ensure that the central axis and concentricity of the second vertical shaft guide hole are consistent with those of the first vertical shaft guide hole.

[0012] Preferably, in the step 4, when drilling the second vertical shaft guide hole, the drilling is stopped when the preset length of the second vertical shaft guide hole is 30 m, and the slag in the first guide shaft below the drilling stop position is cleared.

[0013] In the second aspect, the present application provides a concrete wall protection structure for a soft surrounding rock shaft pilot shaft, which adopts the following technical solution: A concrete wall protection structure for a soft surrounding rock vertical shaft pilot shaft is implemented based on a construction method for a soft surrounding rock vertical shaft pilot shaft described in the above technical solution, and includes a first pilot shaft, a second pilot shaft and a concrete column structure, wherein the concrete column structure is located between the first pilot shaft and the second pilot shaft.

[0014] Preferably, a drainage channel is provided at the inner bottom wall of the second guide shaft, which is inclined downward and faces away from the second guide shaft.

[0015] Preferably, the inner diameter of the drainage channel gradually increases from an end close to the second guide shaft to an end far away from the second guide shaft.

[0016] The present invention has the following advantages and beneficial effects: The present invention accurately controls the drilling process of the pilot well by using a directional drill and a reverse well drill in coordination. In particular, during the construction process, the directional drill is used to make the first pilot hole, and the reverse well drill is used to pull the well back, which not only ensures the construction accuracy, but also avoids the common error problems in traditional construction methods and improves the stability of the pilot well. The concentric circular concrete retaining wall formed by the two pilot wells significantly improves the bearing capacity of the shaft, enhances its supporting effect in the soft surrounding rock, and effectively prevents the collapse of the pilot well and the instability of the well body caused by unstable geological conditions.

[0017] Secondly, the backfill is made of micro-expansion self-compacting concrete, which ensures the compactness and stability of the backfill concrete. The use of this concrete material not only improves the impermeability of the pilot shaft, but also enhances the overall strength and durability of the shaft by forming a uniform and dense concrete column structure, ensuring the stability of the shaft during long-term use.

[0018] In addition, the present invention is particularly aimed at the construction environment with abundant groundwater, and proposes an innovative design of setting a drainage channel at the bottom of the first pilot shaft, which solves the negative impact that groundwater may have on the backfill concrete and the stability of the pilot shaft. Through the inclined drainage channel design, the groundwater can be effectively guided to flow out, avoiding the interference of water flow on the concrete backfill, thereby ensuring the molding quality of the backfill concrete, reducing the impact of water pressure on the pilot shaft structure, and further improving the safety of construction.

[0019] Finally, by precisely controlling the drilling speed, deviation correction amount and deviation correction angle of the second pilot hole construction, the present invention ensures the height concentricity between the second vertical shaft pilot hole and the first pilot hole, thereby ensuring the structural integrity and uniformity of the concrete retaining wall. In particular, by removing the slag when the second pilot hole is drilled to a certain depth, the interference of the slag on the pilot hole structure is prevented, ensuring the smooth progress of the construction process.

[0020] In summary, the soft surrounding rock vertical shaft pilot shaft construction method and its concrete wall protection structure of the present invention effectively solve a series of technical problems in traditional construction methods by optimizing construction technology, improving material selection and innovating drainage design, which not only improves construction efficiency and reduces safety risks, but also ensures the stability and durability of the vertical shaft under complex geological conditions, and has significant economic benefits and social value. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] 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.

[0022] Figure 1 This is a schematic diagram of the structure of the embodiment of the present application. Figure 1 ; Figure 2 is a top view of the structure of an embodiment of the present application; Figure 3 This is a schematic diagram of the structure of the embodiment of the present application. Figure 2 .

[0023] The markings in the figure are: 100. First vertical shaft guide hole; 200. First guide shaft; 300. Concrete column structure; 400. Second vertical shaft guide hole; 500. Second guide shaft; 600. Drainage channel; 700. Concrete retaining wall. DETAILED DESCRIPTION

[0024] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0025] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described here, and the objects distinguished by "first", "second", etc. are generally of one type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0026] Among the related technologies, the application of the reverse well method in shaft excavation and support has become the mainstream construction method for shaft excavation and support because of its low difficulty, high efficiency and good safety. As a mature and widely used technology, the basic operation process of the reverse well method is: first, use a reverse well drilling rig to drill from top to bottom to form a guide hole; then, use the guide hole to install a reaming drill bit at the bottom of the shaft, and gradually expand the guide well by pulling the reaming drill bit from bottom to top, and finally complete the formation of the guide well. Finally, the slag sliding construction process is completed with the help of the guide well, and the slag is efficiently discharged out of the shaft. Compared with the traditional positive shaft excavation method, the reverse well method can not only improve construction efficiency and shorten construction period, but also effectively reduce construction costs and reduce safety risks during construction, especially showing great advantages under complex geological conditions.

[0027] However, although the reverse shaft method has been widely used in the field of shaft excavation and has played a significant role in improving construction efficiency and safety, there are still certain technical difficulties in its construction process, especially in the link of slag removal from the pilot shaft. Slag removal from the pilot shaft is a key task in the reverse shaft construction, and its success is directly related to the smooth progress of the construction process. However, in actual operation, a large amount of slag from the upper excavation surface is often encountered during the slag removal process of the pilot shaft. With the action of gravity, these slag can easily fall into the formed pilot shaft quickly, which will cause certain impact and damage to the pilot shaft structure, especially in areas with complex geological conditions, the problem is more prominent.

[0028] Under unfavorable geological conditions such as weak surrounding rock or broken zones, the stability of the pilot shaft structure may be seriously affected. The geological environment with abundant groundwater exacerbates this problem. Under these conditions, the falling speed and impact force of the slag are greatly increased, which may cause uncontrollable damage to the pilot shaft structure. For example, the collision force of the slag may cause partial collapse of the inner wall of the pilot shaft, and in severe cases, even cause the collapse of the entire section of the pilot shaft. Since the collapse of the pilot shaft will prevent the slag sliding process from proceeding smoothly, it will affect the overall construction progress and safety of the shaft. In severe cases, it will also cause large-scale landslides in the shaft body, increasing the safety risks of personnel during construction. Therefore, how to effectively avoid the collapse of the pilot shaft and ensure the stability of the shaft structure has become an urgent problem that needs to be solved in construction.

[0029] This problem is particularly serious under certain specific geological conditions. Geological conditions such as broken zones and weak rock masses are usually accompanied by the unevenness and instability of the rock formations, making the pilot shaft prone to collapse during construction. Especially in environments with groundwater, the impact of water flow not only exacerbates the fragmentation of the rock formations, but may also cause the stability of the pilot shaft to further decrease, resulting in increased construction risks. What is more complicated is that the collapse of the pilot shaft not only affects the slag sliding effect, but may also cause the support structure of the entire shaft to become unstable, greatly increasing the safety hazards and the probability of accidents during construction. In these complex geological environments, the safety of construction personnel is particularly important, and the stability of the pilot shaft has become a key technical problem in shaft construction.

[0030] In response to these problems, engineering and technical personnel have conducted some explorations to ensure the stability of the pilot well in geological environments such as weak rock and broken zones. Common technical means include strengthening the support of the pilot well, such as using concrete retaining walls, steel casing and other reinforcement measures to increase the impact resistance and collapse resistance of the pilot well. At the same time, during the construction process, it is necessary to continuously monitor the deformation and stability of the pilot well, and take effective measures in time to adjust and repair it to prevent cracks or collapse in the pilot well. In addition, the reasonable selection of appropriate construction parameters, optimization of drilling technology, and the use of shock and impact reduction technical means can also effectively reduce the risk of pilot well collapse.

[0031] In summary, although the reverse shaft method has achieved remarkable results in shaft excavation and support, it still faces many technical challenges in the specific implementation process, especially when facing complex geological environments. The problem of pilot shaft collapse is a major hidden danger in construction and must be given sufficient attention. In the construction of the reverse shaft method, in order to ensure the stability of the pilot shaft and the safety of the entire shaft, it is urgent to improve the construction technology, adopt more accurate and effective construction methods, strengthen the pilot shaft support measures, and combine real-time monitoring and data analysis to adjust the construction plan in time to minimize the safety risks in construction and ensure the smooth progress of the shaft excavation operation.

[0032] Based on this, the present application provides a construction method for a soft surrounding rock vertical shaft guide shaft and a concrete wall protection structure.

[0033] Please refer to Figure 1 to Figure 3 A construction method for a soft surrounding rock vertical shaft pilot shaft comprises the following steps: Step 1: Use a directional drill to drill vertically downward along the rock mass of the vertical shaft to be constructed to form a first vertical shaft guide hole 100, and at the same time confirm the accuracy of the first vertical shaft guide hole 100; Step 2: Use a raise drilling rig to perform a first reverse well drilling to form a first pilot well 200; Step 3: Backfill the bottom of the first pilot shaft 200 with slag back pressure, and pour backfill concrete from the bottom of the first pilot shaft 200 to form a concrete column structure 300 in the first pilot shaft 200; Step 4: Use a directional drill to perform a second pilot hole construction in the center of the concrete column structure 300 backfilled in the first pilot shaft 200 to form a second vertical shaft pilot hole 400, while ensuring that the second vertical shaft pilot hole 400 is located in the center of the concrete column structure 300; Step 5: Use a reverse drilling rig to perform a second reverse pulling well to form a second guide shaft 500 with a diameter smaller than the first guide shaft 200. After the second guide shaft 500 is drilled and formed, the concrete column structure 300 between the first guide shaft 200 and the second guide shaft 500 serves as the concrete retaining wall 700 of the vertical shaft guide shaft.

[0034] On this basis, the first vertical shaft guide hole 100 is accurately drilled by using a directional drill and the accuracy of the first guide hole is ensured, laying the foundation for the subsequent reverse well construction. By accurately controlling the positioning of the guide hole, the potential risks caused by deviation or instability of the guide hole during the construction process are avoided. Secondly, after the reverse well drilling rig completes the first reverse well, the slag is backfilled and poured with concrete to form a solid concrete column structure 300. This measure effectively improves the stability of the guide well, prevents the impact and damage of the slag on the guide well structure during the slag sliding process, and thus greatly reduces the risk of guide well collapse.

[0035] Third, during the second pilot hole construction process, the pilot hole is drilled in the center of the backfill concrete column structure 300 and the second vertical shaft pilot hole 400 is precisely positioned to ensure the accuracy and stability of the second reverse pull well. This process not only enhances the concentricity and structural stability of the pilot shaft, but also adjusts the diameter of the second pilot shaft 500 to form an effective concrete retaining wall 700 between it and the first pilot shaft 200, providing a more solid support for the overall structure of the shaft. This design effectively avoids the collapse of the pilot shaft and the instability of the shaft body under weak surrounding rock and complex geological conditions, and significantly improves the safety during the shaft excavation process.

[0036] In summary, the present invention solves the common problem of pilot shaft collapse in soft surrounding rock shaft construction by using innovative construction methods, multiple pilot shafts, precise pilot hole control and concrete backfilling technology, improves the stability of the pilot shaft, enhances the safety during the construction process, and ensures the stability of the shaft structure. Through this technical solution, the technical difficulties and safety risks faced in construction in soft surrounding rocks and complex geological environments can be significantly reduced, ensuring the smooth progress of shaft excavation construction, and having important engineering application value.

[0037] In some embodiments, the concrete used for backfilling is micro-expansion self-compacting concrete, which is backfilled after the first guide shaft 200 is formed to form a dense concrete column structure 300. By using micro-expansion self-compacting concrete as a backfill material, backfilling is performed after the first guide shaft 200 is formed to form a dense concrete column structure 300. Micro-expansion self-compacting concrete has high fluidity and self-compacting properties, and can fully fill each gap in the guide shaft without vibration, ensuring that the concrete can be evenly distributed and closely fit the guide shaft wall during the backfilling process. Compared with traditional concrete, micro-expansion self-compacting concrete not only improves the filling efficiency and reduces the formation of pores during the backfilling process, but also has a certain expansibility, which can effectively resist the shrinkage caused by water evaporation or temperature changes during the hardening process, and further enhances the overall density and structural strength of the concrete. This dense concrete column structure 300 can effectively enhance the stability of the guide shaft, improve its compressive strength, prevent the collapse or damage of the guide shaft in subsequent construction, ensure the smooth progress of the shaft construction, and also greatly reduce the safety risks during the construction process.

[0038] In some embodiments, in step one, a directional drill is used to form a first vertical shaft guide hole 100 when drilling vertically downward for more than 150 meters along the ground to be constructed. By using a directional drill to drill vertically downward for more than 150 meters along the ground to be constructed in step one to form the first vertical shaft guide hole 100, this practice can ensure the accuracy and stability of the vertical shaft guide hole. In the construction of a vertical shaft with a depth of more than 150 meters, the use of a directional drill can more accurately control the drilling direction and avoid the problem of inaccurate guide hole position caused by construction deviation. The directional drill has high accuracy and stability, can accurately achieve the verticality of the borehole, and effectively avoid the deflection phenomenon that may occur under complex geological conditions. In addition, the borehole with a depth of more than 150 meters needs to ensure a large drilling force and a stable hole wall structure. Therefore, the use of a directional drill can provide better drilling quality and construction efficiency. This precise drilling process lays a solid foundation for the subsequent guide shaft construction, which helps to improve the success rate and safety of the entire vertical shaft guide shaft construction.

[0039] In some embodiments, in step five, the diameter of the first pilot shaft 200 is 60 cm to 80 cm larger than the diameter of the second pilot shaft 500. By ensuring that the diameter of the first pilot shaft 200 is 60 cm to 80 cm larger than the diameter of the second pilot shaft 500, it is helpful to form a reasonable pilot shaft structure and ensure the stability and safety of the shaft construction. Specifically, the larger diameter of the first pilot shaft 200 provides sufficient space for subsequent construction, so that when the well is pulled back, a more stable concrete column structure 300 can be formed, thereby enhancing the bearing capacity and stability of the entire pilot shaft system. The smaller diameter of the second pilot shaft 500 helps to improve the accuracy of the pilot shaft and avoid the looseness or deflection of the structure caused by the excessive diameter. Through the difference in diameter between the two, the effective formation of the concrete retaining wall 700 can be effectively achieved, ensuring that the concrete column plays a good supporting role between the two pilot shafts, thereby improving the overall stability of the shaft, preventing the risk of collapse or deformation under complex geological conditions such as weak surrounding rocks or broken zones, and ensuring the safety of the construction process and the quality of the project.

[0040] In some embodiments, when there is groundwater at the construction site, a drainage channel 600 should be set at a 30° downward and outward tilt at the bottom wall of the first pilot shaft 200 before backfilling the concrete to prevent groundwater from affecting the molding of the backfill concrete. By setting the drainage channel 600 at an angle at the bottom wall of the first pilot shaft 200 before backfilling the concrete, the negative impact of groundwater on the molding of the backfill concrete can be effectively solved. Under geological conditions of weak surrounding rock or abundant groundwater, groundwater may enter the construction area through the bottom wall of the pilot shaft, resulting in excessive water during the pouring of the backfill concrete, affecting the solidification and structural strength of the concrete, and may even cause the concrete to fall off or run off, thereby affecting the quality and stability of the shaft construction. The inclined drainage channel 600 can be set up to timely drain the groundwater entering the pilot shaft, avoid water retention in the concrete backfill area, ensure that the backfill concrete can be formed evenly and stably, thereby improving the density and strength of the concrete column, and ensuring the safety and stability of subsequent construction. This measure not only improves the quality of the backfill work, but also effectively reduces the potential harm of groundwater to the overall structure of the shaft, providing a more reliable guarantee for construction.

[0041] In some embodiments, in step four, before the second pilot hole construction, the drilling speed, correction amount and correction angle of the second pilot hole construction are determined through experiments to ensure that the central axis and concentricity of the second shaft pilot hole 400 are consistent with those of the first shaft pilot hole 100. By conducting experiments before the second pilot hole construction to accurately determine the drilling speed, correction amount and correction angle, it is possible to ensure that the central axis and concentricity of the second shaft pilot hole 400 are completely consistent with those of the first shaft pilot hole 100. This measure effectively solves the problem of deviation that may occur in the construction of pilot holes under complex geological conditions such as weak surrounding rocks. In actual construction, due to the heterogeneity of rock formations and uncertainties in the drilling process, the pilot hole often deviates from the predetermined path, resulting in inaccurate position of the second pilot hole, which in turn affects the quality of the concrete retaining wall 700 and the overall stability of the shaft. By precisely controlling the drilling parameters, the deviation of the pilot hole can be effectively avoided, and the consistency of the pilot hole in concentricity can be ensured, so that the structure of the concrete retaining wall 700 formed by the two pilot wells has higher stability and bearing capacity, avoiding the risk of pilot well deviation on construction quality, thereby greatly improving the accuracy and reliability of shaft construction. In some embodiments, in step 4, when drilling the second vertical shaft guide hole 400, the drilling is stopped when the preset length of the second vertical shaft guide hole 400 is 30 meters, and the slag below the first guide hole 200 located below the stop drilling position is removed. After such arrangement, when drilling the second vertical shaft guide hole 400, by stopping the drilling when the preset length is 30 meters and removing the slag below the first guide hole 200, the slag can be effectively prevented from interfering with the construction of the second guide hole. The slag is easy to accumulate at the bottom of the guide hole during the backfilling process of the first guide hole 200, especially in weak surrounding rock or broken rock formation, and the accumulation of slag may affect the drilling process of the subsequent guide hole. If the slag is not removed in time, it may cause the drill bit resistance to increase, and even cause the guide hole to deviate or make drilling difficult, affecting the construction accuracy and overall structural stability. By stopping the drilling and removing the slag when drilling to a predetermined depth, the smooth construction of the second guide hole can be ensured, and the accuracy and consistency of the drilling path can be maintained, thereby ensuring the stability of the entire construction process and the structural quality of the subsequent concrete retaining wall 700. In addition, this measure also effectively avoids the adverse effects of slag accumulation on concrete backfill, further improving the efficiency and safety of pilot shaft construction.

[0042] Please refer to Figure 1 to Figure 3 The present application also provides a concrete wall protection structure for a soft surrounding rock vertical shaft pilot shaft, which is implemented based on a construction method for a soft surrounding rock vertical shaft pilot shaft in the above-mentioned embodiment, and includes a first pilot shaft 200, a second pilot shaft 500 and a concrete column structure 300, and the concrete column structure 300 is located between the first pilot shaft 200 and the second pilot shaft 500.

[0043] Exemplarily, a drainage channel 600 is provided at the inner bottom wall of the second guide shaft 500, which is inclined downward and faces away from the second guide shaft 500. Furthermore, the inner diameter of the drainage channel 600 gradually increases from one end close to the second guide shaft 500 to one end away from the second guide shaft 500.

[0044] After such setting, the stability and safety of the shaft construction can be effectively improved by optimizing the concrete wall structure and drainage design of the soft surrounding rock shaft pilot shaft. The concrete column provides a strong support for the shaft, ensuring that the pilot shaft can be stably formed in the soft surrounding rock. This structure not only increases the stability of the pilot shaft, but also effectively prevents collapse and leakage caused by soft rock mass, greatly improving the safety during the construction process.

[0045] Next, an inclined drainage channel 600 is set at the inner bottom wall of the second pilot shaft 500, which can effectively guide the flow of groundwater and prevent water from accumulating in the pilot shaft, thereby affecting the quality of concrete backfill and the stability of the pilot shaft. In areas with weak surrounding rocks and abundant groundwater, groundwater may affect the forming and curing of concrete, and may even cause instability in the pilot shaft structure. By setting a drainage channel 600 in the second pilot shaft 500, it can not only effectively prevent water flow accumulation, but also reduce the risk of structural deformation or collapse caused by water pressure, ensuring the smooth progress of the construction process.

[0046] In addition, the inner diameter of the drainage channel 600 gradually increases from the end close to the second pilot shaft 500, which can more effectively improve the drainage effect. As the inner diameter of the drainage channel 600 gradually increases, the flow rate of the water flow is accelerated, and the groundwater is more easily and quickly discharged, avoiding the phenomenon of water accumulation caused by slow water flow. This design enhances the drainage capacity of the drainage channel 600, enabling it to better cope with the construction challenges in areas rich in groundwater, thereby ensuring the backfill quality of the concrete and the stability of the pilot shaft structure, and ultimately improving the overall efficiency and safety of the shaft construction.

[0047] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A construction method for a soft surrounding rock vertical shaft pilot shaft, characterized in that: The following steps are involved: Step 1: using a directional drill to drill vertically downwards along the rock mass of the vertical shaft to be constructed to form a first vertical shaft guide hole (100), and at the same time confirming the accuracy of the first vertical shaft guide hole (100); Step 2: Use a raise drilling rig to perform a first reverse well drilling to form a first pilot well (200); Step three: backfilling the bottom of the first pilot shaft (200) with slag back pressure, and pouring backfill concrete from the bottom of the first pilot shaft (200) to form a concrete column structure (300) in the first pilot shaft (200); Step 4: using a directional drill to perform a second pilot hole construction at the center of the concrete column structure (300) backfilled in the first pilot shaft (200) to form a second vertical shaft pilot hole (400), while ensuring that the second vertical shaft pilot hole (400) is located at the center of the concrete column structure (300); Step 5: Use a reverse drilling machine to perform a second reverse drilling to form a second guide shaft (500) with a diameter smaller than that of the first guide shaft (200). After the second guide shaft (500) is drilled and formed, the concrete column structure (300) between the first guide shaft (200) and the second guide shaft (500) serves as a concrete retaining wall (700) of the vertical shaft guide shaft.

2. The method for constructing a soft surrounding rock vertical shaft pilot shaft according to claim 1, characterized in that: The concrete used for backfilling is micro-expansion self-compacting concrete, and backfilling is performed after the first guide shaft (200) is formed to form a compact concrete column structure (300).

3. The method for constructing a soft surrounding rock vertical shaft pilot shaft according to claim 1, characterized in that: In the step 1, a directional drill is used to drill vertically downward for more than 150 m along the ground to be constructed to form the first vertical shaft guide hole (100).

4. The method for constructing a soft surrounding rock vertical shaft pilot shaft according to claim 1, characterized in that: In the step five, the diameter of the first guide shaft (200) is 60 cm to 80 cm larger than the diameter of the second guide shaft (500).

5. The method for constructing a soft surrounding rock vertical shaft pilot shaft according to claim 1, characterized in that: In the case where there is groundwater at the construction site, a drainage channel (600) should be provided at the bottom wall of the first pilot shaft (200) at an angle of 30° downward and outward before backfilling the concrete, so as to prevent the groundwater from affecting the forming of the backfill concrete.

6. The method for constructing a soft surrounding rock vertical shaft pilot shaft according to claim 1, characterized in that: In the step 4, before the second guide hole construction, the drilling speed, deviation correction amount and deviation correction angle of the second guide hole construction are determined through experiments to ensure that the central axis and concentricity of the second vertical shaft guide hole (400) and the first vertical shaft guide hole (100) are consistent.

7. The method for constructing a soft surrounding rock vertical shaft pilot shaft according to claim 1, characterized in that: In the step 4, when drilling the second vertical shaft guide hole (400), the drilling is stopped when the preset length of the second vertical shaft guide hole (400) is 30 m, and the slag below the drilling stop position of the first guide shaft (200) is cleared.

8. A concrete wall protection structure for a soft surrounding rock vertical shaft pilot shaft, which is realized based on a construction method for a soft surrounding rock vertical shaft pilot shaft according to any one of claims 1 to 7, and is characterized in that: It comprises a first guide shaft (200), a second guide shaft (500) and a concrete column structure (300), wherein the concrete column structure (300) is located between the first guide shaft (200) and the second guide shaft (500).

9. The concrete wall protection structure of a soft surrounding rock vertical shaft pilot shaft according to claim 8, characterized in that: A drainage channel (600) is provided at the inner bottom wall of the second guide shaft (500) in a direction inclined downward and away from the second guide shaft (500).

10. The concrete wall protection structure of a soft surrounding rock vertical shaft pilot shaft according to claim 9, characterized in that: The inner diameter of the drainage channel (600) gradually increases from an end close to the second guide shaft (500) to an end far from the second guide shaft (500).

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