Manual excavation construction method for anti-slide piles under complex geological conditions

Abstract

This invention discloses a method for manually excavating anti-slide piles under complex geological conditions, belonging to the field of slope protection engineering construction technology. The method includes: S1, construction preparation and surveying; S2, staggered excavation, starting with odd-numbered piles and proceeding towards the middle from both ends; S3, geological assessment and dynamic excavation, using manual pneumatic picks, shallow-hole loosening blasting, or water-cooled core drilling followed by central rock breaking, depending on the hardness of the strata; S4, immediate support, pouring retaining walls after each excavation cycle, and implementing specific measures based on adverse geological conditions; S5, reinforcement cage installation and concrete pouring. This invention systematically solves the safety, efficiency, and quality control problems of anti-slide pile construction in complex geological and sensitive environments through intelligent matching of excavation methods and geological risks, and a dynamic and immediate support system. It is particularly suitable for vibration-free excavation of hard rock near important structures.

Description

Technical Field

[0001] This invention relates to the field of slope protection engineering construction technology, specifically to a method for manually excavating anti-slide piles under complex geological conditions, sensitive environments, and high stability requirements. Background Technology

[0002] As transportation infrastructure extends into mountainous areas, linear projects such as highways and railways inevitably traverse mountainous regions with complex geological conditions. In these areas, the stability of roadbed slopes is a particularly prominent issue, and anti-slide piles are often used as the primary retaining structure. Anti-slide piles are pile structures deeply embedded below the potential sliding surface, transferring the landslide thrust to stable strata through the pile body, thereby reinforcing the slope. Manually excavated bored piles are widely used in anti-slide pile construction due to their simple equipment and high adaptability. However, constructing manually excavated bored piles under complex geological conditions faces numerous technical challenges and safety risks:

[0003] The geological conditions are complex and varied: for example, the common bedding sandstone, mudstone and karst strata in Guizhou are prone to geological disasters such as collapse, water inrush, sand inrush and harmful gases (such as methane) during the excavation process.

[0004] High requirements for slope stability: The construction of anti-slide piles may disturb the slope, especially in bedding sections or sections with weak interlayers. Improper construction sequence may induce or aggravate the risk of landslide.

[0005] Construction near sensitive environments: Some anti-slide piles are located near important structures such as oil pipelines and bridge piers, which places extremely strict requirements on the control of construction vibration and deformation, and traditional blasting excavation methods are limited.

[0006] Deep hole operations pose significant safety risks: pile holes are often 20-30 meters deep, presenting major safety risks such as falls from heights, falling objects, suffocation, poisoning, and electric shock. High requirements are placed on the protection of the hole environment and emergency escape procedures.

[0007] The contradiction between construction efficiency and quality: In hard rock formations, manual or pneumatic excavation is extremely inefficient; while conventional blasting causes significant disturbance to retaining walls and slopes, making quality control difficult.

[0008] In existing technologies, shallow-hole loosening blasting is commonly used for tunneling in moderately weathered hard rock strata. However, at special work sites adjacent to vibration-sensitive structures such as oil pipelines and bridge piers, the seismic waves and flyrock generated by traditional blasting techniques can easily damage surrounding facilities, posing extremely high safety risks and being severely constrained by environmental factors. Furthermore, existing conventional manual excavation techniques for bored piles often employ sequential excavation or small-scale skip excavation, lacking macro-level control over potential slope instability risks during construction; when facing sudden adverse geological conditions, the handling measures are simplistic and slow to respond; in sensitive environments, reliance on traditional blasting or mechanical breaking is still present, resulting in insufficient risk control; and safety measures are mostly decentralized, failing to form a closed-loop system. Therefore, there is an urgent need for an integrated construction method that can systematically address the aforementioned challenges. Summary of the Invention

[0009] The purpose of this invention is to provide a method for manually excavating anti-slide piles under complex geological conditions. This method can complete the construction of anti-slide piles safely, efficiently, and with high quality. Especially in areas with adverse geological conditions and sensitive environments, it can effectively control construction risks and ensure the safety of workers and the stability of the surrounding environment.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A method for manually excavating anti-slide piles under complex geological conditions includes the following steps:

[0012] S1. Construction preparation and surveying: Clean up the construction site, lay out the pile positions according to the design drawings, and set up pile hole locks and hole opening safety protection facilities.

[0013] S2. Skip-stake intermittent excavation: Within the same section, skip-stake excavation is carried out in the order of first constructing odd-numbered stakes and then constructing even-numbered stakes, and the construction direction is from both ends of the road section towards the middle.

[0014] S3. Geological Assessment and Dynamic Tunneling: During excavation, geological conditions are assessed in real time, and the appropriate tunneling method is selected based on these conditions.

[0015] For clay layers, gravel layers, or strongly weathered rock layers, excavation is carried out using a combination of manual labor and pneumatic drills, with an advance of 0.8-1.0m per cycle;

[0016] For moderately weathered and more hard rock strata, shallow-hole loosening blasting method is used for tunneling;

[0017] For hard rock strata in sensitive sections near oil pipelines and bridge piers, the method of core drilling along the outline of the pile hole and then breaking the central rock mass is adopted. After forming an annular isolation joint around the pile core rock mass with the water-grinding drill, an inflatable flexible airbag is installed in the isolation joint to provide reverse support. The pile core rock mass is heated and quenched to generate micro-cracks, and a static fracturing agent is injected. The expansion effect of the static fracturing agent in the micro-cracks and the support and guidance of the airbag are used to make the pile core rock mass break in a directional manner towards the isolation joint. The active depressurization of the airbag guides the broken rock mass to collapse towards the center of the pile hole.

[0018] S4. Immediate support: After each tunneling cycle is completed, formwork is erected and concrete retaining wall is poured. When encountering adverse geological conditions, measures are taken to shorten the advance and support, or to use steel sleeves for advance support and then pour retaining wall, or to remove loose materials and then build retaining wall, or to backfill and then construct reinforced concrete retaining wall.

[0019] S5. Reinforcing cage installation and concrete pouring: After the pile hole passes the acceptance test, the reinforcing cage is installed, and the pile body concrete is continuously poured using the tremie pipe method.

[0020] Preferably, step S2 of the skip-pile interval excavation further includes: based on the initial skip sequence, by using sensors deployed on the pile body and the surrounding soil, the stress, deformation and stability of the surrounding soil of each pile are monitored in real time; when the system determines that excavating one of the piles will cause the construction of the adjacent piles to produce lateral displacement exceeding a preset threshold, the pile is automatically skipped and other pile positions are excavated first, forming a dynamic skip sequence.

[0021] Preferably, the specific operational steps for breaking the central rock mass after water-jet drilling and annular coring in step S3 include:

[0022] S31, using the water drill to continuously drill a series of cylindrical water drill core holes along the outline of the pile hole, so that adjacent water drill core holes overlap and intersect, forming a continuous closed annular isolation joint with a width of 160mm and a depth of 50cm to 60cm on the periphery of the pile core rock body.

[0023] S32, several flat high-pressure flexible airbags are implanted in the annular isolation joint. Air is injected into the flexible airbags through the inflation pipeline, so that they expand and simultaneously adhere tightly to the inner side of the pile core rock wall and the outer side of the peripheral hole wall of the annular isolation joint.

[0024] S33, drill a drainage hole in the core rock mass surrounded by the annular isolation joint, insert an electric heating rod into the drainage hole to locally heat the rock mass, and use thermal stress to generate micro-cracks inside the rock mass;

[0025] S34, remove the electric heating rod, use the liquid injection assembly to inject pre-cooling coolant into the drain hole for quenching, and then inject non-explosive chemical static fracturing agent to form a static fracturing agent layer.

[0026] S35, during the hydration and expansion of the static fracturing agent layer, the flexible airbag provides a preset reverse support force to the core rock mass to counteract the lateral pressure transmitted from the core rock mass to the outer borehole wall;

[0027] S36, the expansion pressure of the static fracturing agent layer in the micro-cracks causes the core rock mass to fracture brittlely towards the annular isolation joint. After the core rock mass is fractured, the pressure relief valve actively releases the pressure of the flexible airbag, guiding the fractured rock mass to tilt and collapse towards the central axis of the pile hole, and then the broken pieces are transported out of the hole.

[0028] Preferably, in step S31, the drill rod of the water drill is inclined outward by 3° to 5° relative to the center line of the pile hole to compensate for the occupation of the outer diameter of the drill bit and to form a stepped inverted conical structure in the longitudinal section of the pile hole.

[0029] Preferably, in step S32, a pressure sensor for real-time sensing of lateral pressure is installed on the flexible airbag, and the pressure sensor is electrically connected to an external control terminal.

[0030] Preferably, in step S33, after core drilling and crushing the central rock mass, the depth of the drainage hole is less than or equal to the depth of the annular isolation joint.

[0031] Preferably, during the entire construction process from steps S31 to S36, seismic wave monitoring sensors are installed on structures within a 15-meter radius of the pile hole to monitor and control the particle vibration velocity to within 0.5 cm / s in real time.

[0032] Preferably, step S4, the immediate support step, further includes: after each 0.4-meter to 1.0-meter tunneling cycle, installing steel formwork and pouring C30 early-strength concrete to form a retaining wall; when crossing weak and fractured strata, adding steel mesh to the retaining wall concrete, the steel mesh being made of vertical and circumferential steel bars tied together.

[0033] Preferably, in step S4, when the adverse geological conditions are quicksand or silty soil layers, the countermeasures include: shortening the cyclic advance to 0.4-0.5 meters; erecting formwork and pouring protective concrete, or driving steel bars and wooden boards into the outside of the borehole wall for support before pouring the protective concrete; or using prefabricated steel sleeves to be lowered in sections as advance support, and then pouring protective concrete inside the sleeves.

[0034] Preferably, in step S4, when the adverse geological conditions are karst caves, the countermeasures include: when an unfilled karst cave is exposed, after removing the loose material inside the cave, a cement mortar inner lining is constructed, and a reinforced concrete outer lining is constructed; when a karst cave with filling material is exposed, the accumulated water is pumped out and the cave is over-excavated by 50-100 cm, sandbags are used to backfill and compact the filling, and then a reinforced concrete outer lining is constructed.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. Dynamic intelligent construction: By introducing real-time monitoring and dynamic skipping sequence, the excavation sequence of skipping piles is dynamically optimized, effectively controlling the mutual influence of pile group construction and slope deformation, and improving construction safety and scientificity.

[0037] 2. Intelligent matching of tunneling methods: Based on real-time geological assessment results, three tunneling methods (manual pneumatic pick / shallow-hole blasting / water-powered drilling ring core sampling followed by crushing of the central rock mass) are intelligently matched, which not only ensures the excavation efficiency of hard rock strata, but also ensures vibration-free and safe construction in sensitive environments, achieving a balance between efficiency and safety.

[0038] 3. Vibration-free control for sensitive environments: The innovative combination of water-jet core drilling, flexible airbag support, thermal-quenching fracturing, and static crushing achieves efficient, low-disturbance, and silent crushing of hard rock, perfectly solving the problem of not being able to blast near important structures. Combined with drill pipe outward tilting technology and full-process vibration monitoring, it enables safe, vibration-free, and precise excavation of hard rock adjacent to sensitive structures such as oil pipelines, filling the gap in construction technology in such environments and ensuring absolute safety when constructing near sensitive structures such as oil pipelines. At the same time, it can significantly shorten the waiting time for effective crushing after injecting the fracturing agent to 2-4 hours.

[0039] 4. Dynamic real-time support system: The thickness of the retaining wall, reinforcement and cyclic advance are adjusted according to the depth and geological dynamics. Specific and effective advanced or real-time support measures are proposed for adverse geological conditions such as quicksand, silt and karst caves, which effectively curbs the collapse of the borehole wall. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating the overall construction process of the manual excavation method for anti-slide piles under complex geological conditions, as described in this invention.

[0041] Figure 2 This is a schematic diagram of the construction steps for breaking up the rock mass in the center after water-jet drilling and annular core sampling.

[0042] Figure 3 This is a schematic diagram after core drilling using a water-jet drill.

[0043] Figure 4 A schematic diagram of the construction steps for immediate support in case of adverse geological conditions.

[0044] In the diagram: 1. Core rock mass; 2. Core sampling hole; 3. Disposal hole. Detailed Implementation

[0045] To better understand the purpose, structure, and function of this invention, the invention will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0046] It should be noted that, unless otherwise specified, the methods described in the following embodiments are conventional methods, and the reagents and materials mentioned are commercially available unless otherwise specified. In the description of this invention, the terms "lateral," "longitudinal," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. This embodiment takes the anti-slide pile project of the TJ-2 section of a certain expressway as an example. This project includes 279 anti-slide piles at 8 work sites. The pile cross-sections are mainly 2.0m×3.0m and 1.5m×2.0m, with a maximum pile length of 28m. The geology along the route is complex, involving clay, breccia, strongly weathered to moderately weathered argillaceous sandstone, mudstone, marl, limestone, etc., and there are risks of bedding-parallel landslides, karst development areas, and sensitive environments such as proximity to oil pipelines and bridge piers.

[0048] Example 1: Taking the right-side anti-slide pile (complex bedding slope) of the K43+300~K43+515 section as an example.

[0049] This section is designed with 73 piles, each 28m long, located on a steep, bedding slope. The upper part is covered by a thick layer of gravel, and the underlying rock is strongly to moderately weathered sandstone. The rock strata have a small angle between their dip and the slope aspect, making them prone to slippage. The design employs two rows of piles, one above the other.

[0050] like Figure 1 As shown, this invention provides a method for manually excavating anti-slide piles under complex geological conditions, comprising the following steps:

[0051] S1. Construction preparation and surveying: Clean up the construction site, lay out the pile positions according to the design drawings, and set up pile hole locks and hole opening safety protection facilities.

[0052] Specifically, a construction access road was built, and the site for the pile locations was leveled. The center point (O) and four corner points (A, B, C, D) of each pile were accurately laid out using a total station, and the protective piles were surveyed. Drainage ditches were constructed around the piles.

[0053] S2, Intermittent Excavation with Jump Stakes (Combined with Dynamic Jump Sequence): Within the same section, jump excavation is carried out in the order of first constructing odd-numbered stakes and then constructing even-numbered stakes, and the construction direction is from both ends of the road section towards the middle.

[0054] Furthermore, based on the initial skip sequence, sensors deployed on the pile body and surrounding soil are used to monitor the stress, deformation, and stability of the surrounding soil of each pile in real time. When the system determines that excavating one of the piles will cause the construction of adjacent piles to produce lateral displacements exceeding a preset threshold, it automatically skips that pile and prioritizes the excavation of other pile positions, thus forming a dynamic skip sequence.

[0055] Specifically, the monitoring equipment will be deployed first: a high-precision displacement monitoring point (such as a small GNSS module or total station prism) will be installed on the interlock of each completed pile hole, and a stress monitoring instrument will be installed on the pile body. At key locations on the slope of the construction section, 1-2 inclinometers will be installed to monitor deep soil slippage. All monitoring equipment will transmit data (such as coordinates and displacement) to the project's central monitoring computer in real time via a wireless network.

[0056] Then, set the "skip-stake" rules and thresholds. Initial skip sequence: Determine a starting point, for example, "starting from one end of the road segment, construct all stakes with odd numbers first, then construct stakes with even numbers." Safety threshold: Before construction, determine the "daily displacement alarm value for the stake top," for example, 3 mm / day, based on design requirements and geological conditions. Simultaneously, set a rate of change threshold for deep soil displacement, for example, 2 mm / day.

[0057] The implementation steps of dynamic skip-sequence: After construction begins, the following cyclical process is followed: Step 1, excavation and continuous monitoring according to the initial sequence. The construction team first begins excavating piles according to the established "initial skip-sequence". At the same time, the central monitoring computer continuously receives and displays real-time data from all deployed monitoring points. Step 2, assessing the risk of the next pile to be excavated. Before planning to excavate the next pile in the "initial skip-sequence" (let's say "pile 5"), the system operator or automatic decision-making program will perform the following risk assessment: Check the status of adjacent piles: Focus on checking the monitoring data of piles adjacent to pile 5 that have already been constructed (e.g., piles 3 and 7). Observe their current overall displacement, especially the rate of displacement change in the last 24 hours. Model prediction (simple judgment): Based on a simplified assessment model (or empirical formula) pre-input into the computer, the displacement rate of the current adjacent piles (pile 3, pile 7) and the deep soil displacement data are used as input. The model quickly calculates and outputs a predicted value: "If pile 5 is excavated at this time, how much additional daily displacement increment is expected to occur in pile 3 (or pile 7)?" Risk Assessment: The "additional displacement increment" predicted by the above model is added to the current measured displacement rate of pile No. 3 to obtain an "expected total displacement rate". This "expected total displacement rate" is compared with the pre-set safety threshold (3 mm / day). Step 3: Make a "pile skipping" or "excavation" decision. Case A (triggering "pile skipping"): If the calculated "expected total displacement rate" exceeds the safety threshold of 3 mm / day, the system determines that "excavating pile No. 5 is risky at this time". In this case, the system will automatically mark pile No. 5 as "postponed" and skip this pile. Case B (excavation allowed): If the "expected total displacement rate" is lower than or equal to the safety threshold, the risk is determined to be controllable, and pile No. 5 can be excavated as planned. Step 4: Select the next safe pile location and execute. When "pile skipping" (case A) is triggered, the system automatically selects the next candidate pile from the remaining unconstructed piles according to the "pile skipping interval" principle (e.g., skipping at least one pile), e.g., skipping No. 5 and selecting pile No. 9. Repeat the risk assessment of steps 2 and 3 for pile No. 9. If the assessment of pile number 9 passes, the construction team is instructed to excavate pile number 9. If the assessment still fails, the search continues until a pile location predicted by the model is found.

[0058] Example of dynamic skipping sequence formation. Take a slope with 7 piles (numbered 1 to 7) as an example: Initial plan: odd-number priority, order is 1# -> 3# -> 5# -> 7# -> 2# -> 4# -> 6#. Dynamic execution process: 1. Safely complete piles 1# and 3#. 2. Before excavating pile 5#, the system assessment finds that the current displacement rate of pile 3# has reached 1.5 mm / day, and the model predicts that excavating pile 5# will increase it by another 2.0 mm / day, with a predicted total rate of 3.5 mm / day > the threshold of 3.0 mm / day. Decision: Skip pile 5#. 3. The system assesses the next candidate pile 7#: the prediction is that it will have little impact on pile 3#, and the surrounding conditions of pile 7# are more stable. Decision: Excavate pile 7# first. 4. After completing pile 7#, the system reassesses pile 5#, possibly because the stress adjustment after the construction of pile 7# has reduced the predicted risk. Decision: Go back to excavating pile 5#. 5. The decision to excavate piles #2, #4, or #6 will be made based on each assessment. The final actual sequence may become: #1 -> #3 -> #7 -> #5 -> #2 -> #6 -> #4. This sequence is dynamically generated based on the results of "real-time judgment" during construction, always prioritizing the safest location at any given time.

[0059] The aforementioned dynamic skipping construction method, through a cycle of "monitoring-rapid prediction-threshold comparison", transforms complex geotechnical engineering problems into clear binary decisions ("dig" or "skip"), enabling on-site personnel to intuitively understand and execute the method. It effectively controls construction risks and optimizes the construction process without over-reliance on complex calculations.

[0060] S3. Geological Assessment and Dynamic Tunneling: During excavation, geological conditions are assessed in real time, and the appropriate tunneling method is selected based on these conditions.

[0061] For clay layers, gravel layers, or strongly weathered rock layers, excavation is carried out using a combination of manual labor and pneumatic drills, with an advance of 0.8-1.0m per cycle;

[0062] For moderately weathered and more hard rock strata, shallow-hole loosening blasting method is used for tunneling;

[0063] For hard rock strata in sensitive sections near oil pipelines and bridge piers, a method of core drilling along the outline of the pile hole using a water-jet drill is adopted to break the central rock mass. After forming an annular isolation joint around the pile core rock mass using a water-jet drill, an inflatable flexible airbag is installed in the isolation joint to provide reverse support. The pile core rock mass is heated and quenched to generate micro-cracks, and a static fracturing agent is injected. The expansion of the static fracturing agent in the micro-cracks, along with the support and guidance of the airbag, causes the pile core rock mass to be directionally broken towards the isolation joint, and the active depressurization of the airbag guides the broken rock mass to collapse towards the center of the pile hole.

[0064] Specifically, when excavating to the upper gravel cover layer and the strongly weathered sandstone layer, manual excavation was carried out in conjunction with G10 pneumatic picks, with the advance rate controlled at 1.0m per cycle.

[0065] Upon entering the moderately weathered sandstone layer, the rock hardens, necessitating a shallow-hole loosening blasting method. First, a slot is drilled in the center of the pile hole using a pneumatic drill to create a free face. Then, peripheral holes are drilled along the designed pile hole outline, with a depth of 0.8-1.0m. The charge per hole is strictly controlled (calculated based on rock hardness, generally not exceeding 0.3kg). Immediately after blasting, a frame is erected at the wellhead using square timber (150mm×150mm), covered with steel mesh (φ18, 200mm×200mm mesh) and sandbags for protection against flying rocks.

[0066] For shallow-hole loosening blasting, the preferred borehole depth is 0.8 to 1.0 meters, and the borehole diameter is no more than 42 millimeters. By limiting the depth and diameter of the borehole, the charge amount per hole can be effectively controlled, thereby limiting the energy and impact range of the shock wave generated by the blast to a local area and avoiding excessive disturbance to the surrounding rock and soil. This is especially suitable for rock breaking operations in areas with sensitive slope stability.

[0067] Furthermore, shallow-hole loosening blasting employs a millisecond-delay initiation network, such as using non-electric detonating cord detonators or electronic detonators, to divide multiple blast holes within the same pile hole into several segments, which are then detonated sequentially at preset millisecond time intervals. This initiation method can disperse the total charge of a single blast over time, significantly reducing the peak blast vibration, and utilizes the first-detonated blast holes to create new free faces for subsequent blast holes, thereby improving rock fragmentation efficiency, reducing the proportion of large blocks, and further ensuring the safety of slopes and adjacent structures.

[0068] Furthermore, during the shallow-hole loosening blasting, a multi-layered composite protective structure is installed at the borehole opening. This structure, from bottom to top, typically includes: a layer of "well"-shaped square timbers laid over the borehole opening; a steel mesh covering the timbers; and a layer of sandbags stacked on top of the steel mesh or a thick steel plate covering it. This composite protective system effectively absorbs and blocks flying rocks and shock waves generated by the blasting, preventing them from exiting the borehole and causing personnel injury or equipment damage. It is a key physical barrier for achieving "controlled blasting."

[0069] When excavating into hard rock layers in sensitive areas near oil pipelines and bridge piers, annular isolation joints are formed around the core rock mass using a water-jet drill. Inflatable flexible airbags are then installed within the isolation joints to provide reverse support. The core rock mass is heated and quenched to create micro-fractures, and a static fracturing agent is injected. The expansion of the static fracturing agent in the micro-fractures, combined with the support and guidance of the airbags, causes the core rock mass to fracture directionally towards the isolation joint. The active depressurization of the airbags guides the fractured rock mass to collapse towards the center of the pile hole. This process avoids the risk of blasting vibration and ensures the accuracy of hole formation and the continuity of construction. This approach precisely matches the tunneling method with geological characteristics and environmental risks, thereby systematically solving the multi-objective optimization problem of safety, efficiency, and environmental protection under complex conditions: for soft rock strata, manual pneumatic picks are used to control the advance, reducing the risk of collapse from the source and creating conditions for immediate support; for general hard rock, loosening blasting is used, significantly breaking through the bottleneck of tunneling efficiency; and for hard rock adjacent to sensitive structures, a novel process of water-jet drilling for annular core sampling and airbag support, as well as rock mass cold and heat treatment and application of static fracturing agents, is adopted to achieve continuous operation under the premise of ensuring absolute vibration-free safety.

[0070] S4. Immediate support: After each tunneling cycle is completed, formwork is erected and concrete retaining wall is poured. When encountering adverse geological conditions, measures are taken to shorten the advance and support, or to use steel sleeves for advance support and then pour retaining wall, or to remove loose materials and then build retaining wall, or to backfill and then construct reinforced concrete retaining wall.

[0071] Specifically, after each excavation cycle (approximately 1.0m), prefabricated steel formwork is immediately erected, and C30 concrete retaining wall is poured, with a thickness of 20cm. When the excavation depth exceeds 10m, a steel mesh is added inside the retaining wall: vertical reinforcement φ12@200mm, circumferential reinforcement φ8@300mm. An early-strength agent is added to the concrete to accelerate formwork removal (strength reaches 12.5MPa).

[0072] For concrete retaining walls, the reinforcing mesh may further include diagonal reinforcing bars, which are welded or tied to vertical and circumferential reinforcing bars to form a spatial mesh structure. The addition of these diagonal reinforcing bars effectively resists shear stress and torque that the retaining wall may experience. Especially when geological conditions are uneven or there are differences in lateral pressure, it can significantly improve the integrity and deformation resistance of the retaining wall, preventing cracking or localized damage under complex stress conditions.

[0073] Furthermore, fiber-reinforcing materials, such as steel fibers, synthetic fibers, or glass fibers, can be incorporated into the concrete of the retaining wall. These fibers are uniformly distributed in the concrete matrix, forming a three-dimensional randomized support system. This system can suppress the generation and development of microcracks during the plastic shrinkage and hardening process of concrete, thereby improving the crack resistance, toughness, and impact resistance of the retaining wall concrete. This makes it more adaptable to adverse conditions such as rockfall or localized stress concentration that may be encountered during excavation.

[0074] Furthermore, a grouting reinforcement layer can be installed between the concrete retaining wall and the surrounding soil and rock mass. Specifically, grouting pipes can be pre-installed on the outside of the retaining wall. After the retaining wall reaches a certain strength, cement grout or chemical grout is injected into the gaps between the retaining wall and the borehole wall or into the surrounding loose soil and rock mass through the grouting pipes. This fills the gaps, consolidates the weak strata, and tightly bonds the retaining wall with the surrounding strata, forming a composite structure that works synergistically. This not only enhances the stability of the retaining wall but also improves the mechanical properties of the surrounding strata, providing more uniform lateral restraint for the subsequent pile stress.

[0075] S5. Reinforcing cage installation and concrete pouring: After the pile hole passes the acceptance test, the reinforcing cage is installed, and the pile body concrete is continuously poured using the tremie pipe method.

[0076] Specifically, the reinforcing cage is fabricated centrally at the processing plant, with the main reinforcement bars connected using straight threaded sleeves. After passing inspection, it is lowered in sections using a crane and tied into shape inside the borehole. Concrete is poured using a tremie pipe, with a free fall drop of no more than 2 meters, and is vibrated in layers, completing the process continuously in one go.

[0077] Example 2: Taking the anti-slide piles on the right side of the BK1+184~BK1+229 section of the Zazuo Interchange (near the oil pipeline) as an example. Here, BK1+184~BK1+229 of the Zazuo Interchange refers to the construction section from 1 km 184 m to 1 km 229 m on the B ramp of the Zazuo Interchange.

[0078] The minimum horizontal distance between the anti-slide piles and the oil pipeline is only 14m, and blasting is strictly prohibited.

[0079] like Figure 2 , Figure 3 As shown, the present invention provides a method for constructing a fractured rock mass in a sensitive section of hard rock strata near oil pipelines and bridge piers using a water-jet drilling ring core sampling method. Figure 3 The image shown is a schematic diagram of the pile rock after ring core sampling with a water-jet drill.

[0080] S3. Geological identification and dynamic tunneling: Geological conditions are identified in real time during the excavation process, and the corresponding tunneling method is selected according to the geological conditions: For hard rock layers in sensitive sections near oil pipelines and bridge piers, tunneling is carried out by using a water-cooled drill to extract cores along the outline of the pile hole and then breaking the central rock mass.

[0081] Specifically, this section mainly consists of moderately weathered conglomerate with high hardness. A special process was employed, involving ring core drilling followed by crushing of the central rock mass. The specific steps are as follows: The annular isolation joint is formed, i.e., step S31: a 160mm diameter water-cooled drill bit is used to drill a hole in the core rock mass 1. To ensure the hole size, the drill rod is adjusted to tilt 4° outward from the pile hole when the drilling rig is in place. A series of core holes 2 are continuously drilled along the designed 2.0m × 1.5m rectangular pile hole outline. The core holes 2 are continuously arranged, closely connected, and interconnected, forming a continuous closed annular outline, which together constitutes the annular isolation joint surrounding the core rock mass 1; the width of the annular isolation joint is the same as the diameter of the core hole, approximately 160mm, and the depth is 55cm. The annular isolation joint is a closed rectangular ring formed by a series of tightly connected core holes 2, which is the outer ring of the hole. Due to the outward tilt of the drill rod, the hole wall formed by this cycle is slightly outwardly flared inverted trapezoidal, providing space for the drilling rig to be positioned in the next cycle and preventing hole shrinkage.

[0082] The high-pressure flexible airbag implantation, or step S32, involves implanting multiple specially designed flat high-pressure flexible airbags within the annular isolation joint. Each flexible airbag is connected to an external inflation pump via inflation tubing. The airbag surface has anti-slip textures and is equipped with a pressure sensor. After inflation, the flexible airbag's outer wall adheres tightly to the outer borehole wall, while its inner wall adheres tightly to the pile core rock mass. The pressure sensor monitors the pressure in real time and transmits the signal to an external control terminal, adjusting the inflation pressure to maintain it at a preset equilibrium pressure value. This provides an inward pre-tightening support force to the pile core rock mass and also provides a flexible protective layer to the outer borehole wall.

[0083] Insertion of the electric heating rod, i.e., step S33: Drill a drainage hole 3 in the core rock mass 1, the depth of which is less than or equal to the depth of the annular isolation joint. Start the ground control power supply, supplying power to the electric heating rod inserted into the drainage hole via a wire. Control the heating temperature between 200℃ and 300℃, and maintain the heating time for 20-30 minutes. The electric heating rod conducts heat energy to the core rock mass 1, causing its local temperature to rise rapidly. Due to the anisotropic physical properties of the rock, extremely large non-uniform thermal stress is generated internally, leading to a weakening of the bonding force between rock particles and inducing a large number of radially distributed micro-cracks around the drainage hole 3, forming a weakened area within a certain range.

[0084] Injection of quenching agent and static fracturing agent, i.e., step S34: Remove the electric heating rod from the hole. Immediately operate the injection assembly, using a high-pressure pump to force the pre-cooled coolant from the storage tank into the drainage hole 3 through the injection nozzle. The high-temperature rock undergoes sudden contraction upon cooling, i.e., the "quenching" effect, which promotes the further expansion and connection of micro-fractures towards the annular isolation joint. Then, non-explosive chemical static fracturing agent is filled into the drainage hole 3 to form a static fracturing agent layer. The expansion pressure generated by the fracturing agent during the hydration reaction directly acts on the inner wall of the existing micro-fractures.

[0085] The airbag provides dynamic reverse support, as described in step S35: During the hydration reaction following the injection of the static fracturing agent, its volume will expand significantly, generating enormous expansion pressure. At this point, the pre-inflated flexible airbag comes into play. Through its internal pressure, the airbag continuously applies a pre-set reverse support force F, pointing towards the central axis of the pile hole, to the core rock mass 1. r This force directly counteracts the lateral pressure F generated by the expansion of the static fracturing agent, which attempts to push the pile core rock mass towards the outer borehole wall. e This dynamic equilibrium constraint ensures that the expansion pressure is mainly concentrated on the propagation of microcracks and forces newly formed cracks to preferentially develop towards the annular isolation joint where stress is most concentrated and mechanically weakened, rather than spreading disorderly to the surrounding rock mass, thus protecting the stability of the borehole wall.

[0086] Induced inward fracturing and controlled slag removal, step S36: Under the combined and precise action of the static fracturing agent expansion pressure and the reverse support force of the flexible airbag, the core rock mass 1 ultimately undergoes brittle fracture along the weakest surface, the annular isolation joint, achieving overall fracturing. After fracturing, the gas inside the flexible airbag is actively and slowly released through the pressure relief valve on the inflation pipeline, causing it to contract. The fractured rock mass, having lost lateral support, tilts and collapses towards the central axis of the pile hole under the action of gravity and slight inward stress, accumulating in the central area at the bottom of the hole. Subsequently, a small grab bucket or underwater slag removal equipment can efficiently transport the fractured blocks out of the hole, completing the rock mass removal. The entire process avoids squeezing and friction with the outer hole wall, ensuring the safety and efficiency of the construction.

[0087] Optionally, when processing extremely hard granite, a pulsed heating and liquid injection method can be used, i.e., multiple cycles of "heating-water injection" to accumulate thermal damage energy. In addition, electric heating rods can be replaced with high-pressure, high-temperature steam nozzles to further improve heat exchange efficiency through steam permeation.

[0088] Vibration monitoring: Seismic wave monitoring sensors are deployed in the valve chamber of the oil pipeline and on the adjacent ground for real-time monitoring throughout the entire process. The expansion pressure generated by the hydration reaction of the static fracturing agent causes the rock mass to slowly crack along the crystal lattice or weak surfaces. The maximum particle vibration velocity measured is only 0.3 cm / s, far below the safety control standard of 0.5 cm / s, and has no impact on the oil pipeline.

[0089] The above-described construction scheme for fracturing the rock mass after annular core drilling utilizes a pre-formed annular isolation joint created by the water-grinding drill. Combined with the synergistic effects of flexible airbag active support, thermal shock weakening of the rock mass, and static fracturing agent expansion fracturing, safe, precise, and efficient fracturing of the core rock mass is achieved. The controllable reverse support force provided by the flexible airbag effectively counteracts the lateral pressure during the fracturing process, ensuring borehole stability. The coupling effect of thermal stress and chemical expansion significantly reduces the rock mass strength, making fracturing more easily guided towards the pre-set isolation joint, resulting in an inward, orderly collapse. Coupled with full-process vibration monitoring (particle vibration velocity ≤0.5cm / s), disturbance to surrounding rock masses and adjacent structures is significantly reduced. Furthermore, the fracturing time for hard rock is significantly shortened compared to traditional construction methods; the waiting time for effective fracturing after injecting the fracturing agent is drastically reduced to 2-4 hours, making it particularly suitable for fracturing hard rock masses near sensitive structures.

[0090] Example 3: Immediate support in adverse geological conditions

[0091] like Figure 4 As shown, the present invention provides a construction method for immediate support in the event of adverse geological conditions.

[0092] S4. Immediate Support: After each tunneling cycle, formwork is erected and concrete retaining wall is poured. When encountering adverse geological conditions, measures are taken such as shortening the advance and providing support, using steel sleeves for advance support before pouring the retaining wall, removing loose materials before constructing the retaining wall, or backfilling before constructing a reinforced concrete retaining wall.

[0093] Furthermore, the step S4 immediate support also includes: after each 0.4-meter to 1.0-meter tunneling cycle, installing steel formwork and pouring C30 early-strength concrete to form a retaining wall; when crossing weak and fractured strata, adding steel mesh to the retaining wall concrete, the steel mesh being made of vertical and circumferential steel bars tied together.

[0094] Furthermore, in step S4, when the adverse geological conditions are quicksand or silty soil layers, the countermeasures include: shortening the cycle advance to 0.4-0.5 meters; erecting formwork and pouring protective concrete, or driving steel bars and wooden boards into the outside of the borehole wall for support before pouring the protective concrete; or lowering prefabricated steel sleeves in sections as advance support, and then pouring protective concrete inside the sleeves.

[0095] Furthermore, in step S4, when the adverse geological conditions are karst caves, when an unfilled karst cave is exposed, after removing the loose material inside the cave, the inner lining is constructed with cement mortar, and a reinforced concrete wall is constructed on the outside; when a karst cave with filling material is exposed, the accumulated water is pumped out and the cave is over-excavated by 50-100 cm, sandbags are used to backfill and compact the filling, and then a reinforced concrete wall is constructed.

[0096] Specifically, when encountering quicksand layers, once quicksand is encountered at a certain depth during excavation, the cycle advance is immediately shortened to 0.4m. Workers quickly drive approximately 1.5m long φ22 steel bars and wooden planks into the outside of the borehole wall to form a temporary baffle, embedding it at least 0.3m into the stable soil layer below, with the upper end embedded in the back of the already poured retaining wall. Formwork is then quickly erected, and C30 concrete mixed with a quick-setting agent is poured to form the retaining wall. This successfully suppresses the development of quicksand and ensures the stability of the borehole wall.

[0097] When encountering severe quicksand or silty soil layers during excavation, advanced support can be adopted. This includes temporary or permanent support structures constructed in advance in front of the soil to be excavated or soft strata before or during the excavation cycle to actively control the stability of the excavation face and borehole wall, preventing collapse or quicksand inflow. Precast steel sleeves or sheet piles can be lowered in sections, with their lower ends extending a certain depth ahead of the excavation face to form a rigid cylindrical or slab-like retaining wall, providing a closed working space for subsequent safe excavation and retaining wall pouring.

[0098] Furthermore, advanced support is employed, specifically segmented precast steel sleeve support. This steel sleeve is assembled from multiple sections of arc-shaped steel plates connected by high-strength bolts, with an inner diameter slightly larger than the designed diameter of the pile hole. During construction, before excavating and excavating to expose quicksand or extremely unstable soil layers, the first section of the steel sleeve is vertically lowered to the bottom of the hole using a hoisting device, ensuring its bottom cutting edge cuts into the stratum. As the excavation face descends, the steel sleeve is extended and pressed down section by section, always maintaining the bottom of the sleeve at least 0.5 meters ahead of the excavation face. This allows for the excavation and removal of the internal soil under the circumferential constraint of the sleeve, until the unfavorable stratum is penetrated.

[0099] Furthermore, the advanced support system can also include a recyclable micro-steel pipe pile advanced support system. This system involves pre-driving a ring or partially fan-shaped array of micro-steel pipe piles at a certain distance outside the pile hole outline. These micro-steel pipe piles are grouted to solidify with the surrounding soil, forming a reinforced curtain. This curtain effectively blocks groundwater seepage paths, reinforces the loose soil around the piles, improves its self-stabilizing capacity, and provides advanced reinforcement for pile hole excavation. After the pile body concrete is poured, some of the steel pipe piles can be recycled and reused.

[0100] When encountering a karst cave, for an unfilled cave, a small dry cave was exposed at K18+630. First, loose soil and gravel inside the cave were removed. Then, Mu10 hollow bricks were laid using M10 cement mortar to construct a 24cm thick inner lining wall. After the mortar reached its strength, formwork was erected around it, and a double-layer steel mesh (φ14@150mm) was tied. C30 concrete was then poured to form a reinforced permanent retaining wall, which was reliably connected to the upper retaining wall.

[0101] For the infilled karst cave, a mud-bearing karst cave with a small amount of seepage was discovered at another work site. The water was immediately pumped out using a submersible pump, and then the excavation was over-excavated by 80cm to the stable rock surface. Dry sand was filled into woven bags, tightly stacked, and manually compacted to backfill the over-excavated area. Subsequently, a formwork was erected on the surface of the sandbag backfill, and a reinforced concrete retaining wall was poured, increasing the wall thickness to 25cm and reinforcing it. This process was repeated until the karst cave section was traversed.

[0102] The above-mentioned construction plan for immediate support achieves synergistic optimization of safety, efficiency, and cost by matching the support strength with geological risks in real time: standardized cyclic wall protection ensures a continuous construction rhythm in conventional strata; geological risks trigger reinforcement of steel mesh, proactively improving structural safety and strength; and the complete set of emergency measures (such as temporary supports, steel sleeve advanced support, and differentiated karst cave treatment processes) pre-set for extreme adverse geological conditions such as quicksand, silt, and karst caves enable rapid and precise handling of sudden risks, greatly suppressing borehole wall deformation and collapse, and providing stable protection throughout the entire process for deep hole excavation in complex strata.

[0103] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention, and other modifications can be easily implemented by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A method for the construction of anti-slide piles by manual excavation in complex geological conditions, characterized in that, Includes the following steps: S1. Construction preparation and surveying: Clean up the construction site, lay out the pile positions according to the design drawings, and set up pile hole locks and hole opening safety protection facilities. S2. Skip-stake intermittent excavation: Within the same section, skip-stake excavation is carried out in the order of first constructing odd-numbered stakes and then constructing even-numbered stakes, and the construction direction is from both ends of the road section towards the middle. S3. Geological Assessment and Dynamic Tunneling: During excavation, geological conditions are assessed in real time, and the appropriate tunneling method is selected based on these conditions. For clay layers, gravel layers, or strongly weathered rock layers, excavation is carried out using a combination of manual labor and pneumatic drills, with an advance of 0.8-1.0m per cycle; For moderately weathered and more hard rock strata, shallow-hole loosening blasting method is used for tunneling; For hard rock strata in sensitive sections near oil pipelines and bridge piers, the method of core drilling along the outline of the pile hole and then breaking the central rock mass is adopted. After forming an annular isolation joint around the pile core rock mass with the water-grinding drill, an inflatable flexible airbag is installed in the isolation joint to provide reverse support. The pile core rock mass is heated and quenched to generate micro-cracks, and a static fracturing agent is injected. The expansion effect of the static fracturing agent in the micro-cracks and the support and guidance of the airbag are used to make the pile core rock mass break in a directional manner towards the isolation joint. The active depressurization of the airbag guides the broken rock mass to collapse towards the center of the pile hole. S4. Immediate support: After each tunneling cycle is completed, formwork is erected and concrete retaining wall is poured. When encountering adverse geological conditions, measures are taken to shorten the advance and support, or to use steel sleeves for advance support and then pour retaining wall, or to remove loose materials and then build retaining wall, or to backfill and then construct reinforced concrete retaining wall. S5. Reinforcing cage installation and concrete pouring: After the pile hole passes the acceptance test, the reinforcing cage is installed, and the pile body concrete is continuously poured using the tremie pipe method.

2. The method according to claim 1, wherein, Step S2, the skip-pile interval excavation, also includes: based on the initial skip sequence, by deploying sensors on the pile body and the surrounding soil, the stress, deformation and stability of the surrounding soil of each pile are monitored in real time; when the system determines that excavating one of the piles will cause the adjacent piles to have a lateral displacement exceeding the preset threshold, the system automatically skips the pile and prioritizes the excavation of other pile positions, forming a dynamic skip sequence.

3. The method according to claim 1, wherein, The specific operational steps for breaking the central rock mass after water-jet drilling and annular coring in step S3 include: S31, using the water drill to continuously drill a series of cylindrical water drill core holes along the outline of the pile hole, so that adjacent water drill core holes overlap, forming a continuous closed annular isolation joint with a width of 160mm and a depth of 50cm to 60cm on the periphery of the pile core rock body. S32, several flat high-pressure flexible airbags are implanted in the annular isolation joint. Air is injected into the flexible airbags through the inflation pipeline, so that they expand and simultaneously adhere tightly to the inner side of the pile core rock wall and the outer side of the peripheral hole wall of the annular isolation joint. S33, drill a drainage hole in the core rock mass surrounded by the annular isolation joint, insert an electric heating rod into the drainage hole to locally heat the rock mass, and use thermal stress to generate micro-cracks inside the rock mass; S34, remove the electric heating rod, use the liquid injection assembly to inject pre-cooling coolant into the drain hole for quenching, and then inject non-explosive chemical static fracturing agent to form a static fracturing agent layer. S35, during the hydration and expansion of the static fracturing agent layer, the flexible airbag provides a preset reverse support force to the core rock mass to counteract the lateral pressure transmitted from the core rock mass to the outer borehole wall; S36, the expansion pressure of the static fracturing agent layer in the micro-cracks causes the core rock mass to fracture brittlely towards the annular isolation joint. After the core rock mass is fractured, the pressure relief valve actively releases the pressure of the flexible airbag, guiding the fractured rock mass to tilt and collapse towards the central axis of the pile hole, and then the broken pieces are transported out of the hole.

4. The construction method of the anti-slide pile in complex geological conditions according to claim 3, characterized in that, In step S31, the drill rod of the water drill is tilted outward by 3° to 5° relative to the center line of the pile hole to drill, so as to compensate for the occupation of the outer diameter of the drill bit and make the longitudinal section of the pile hole form a stepped inverted conical structure.

5. The method according to claim 3, wherein, In step S32, a pressure sensor for real-time sensing of lateral pressure is installed on the flexible airbag, and the pressure sensor is electrically connected to an external control terminal.

6. The method according to claim 3, wherein, In step S33, the depth of the drainage hole is less than or equal to the depth of the annular isolation seam.

7. The method according to claim 3, wherein, Throughout the construction process from steps S31 to S36, seismic wave monitoring sensors are installed on structures within a 15-meter radius of the pile hole to monitor and control the particle vibration velocity to within 0.5 cm / s in real time.

8. The method according to claim 1, wherein, The steps of step S4, immediate support, also include: after each 0.4-meter to 1.0-meter tunneling cycle, installing steel formwork and pouring C30 early-strength concrete to form a retaining wall; when crossing weak and fractured strata, adding steel mesh to the retaining wall concrete, the steel mesh being made of vertical and circumferential steel bars tied together.

9. The method according to claim 8, wherein, In step S4, when the adverse geological conditions are quicksand or silty soil layers, the following countermeasures are taken: shorten the cycle advance to 0.4-0.5 meters; erect formwork and pour protective concrete, or drive steel bars and wooden boards into the outside of the borehole wall for support before pouring the protective concrete; or use prefabricated steel sleeves to be lowered in sections as advance support, and then pour protective concrete inside the sleeves.

10. The method according to claim 8, wherein, In step S4, when the adverse geological conditions are karst caves, the following countermeasures are taken: when an unfilled karst cave is exposed, after removing the loose material inside the cave, the inner lining is constructed with cement mortar, and a reinforced concrete wall is constructed on the outside; when a karst cave with filling material is exposed, after pumping out the accumulated water, the cave is over-excavated by 50-100 cm, backfilled with sandbags and compacted, and then a reinforced concrete wall is constructed.

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