A method for staged trench excavation and support construction of roadbed anti-slide piles

Abstract

This application belongs to the field of roadbed construction technology, specifically relating to a method for staged excavation and support construction of anti-slide piles. Based on the distribution characteristics of the anti-slide pile group and geological data of the pile location area, this method determines the excavation sequence and the adjustment rules for the staged excavation amplitude. It sequentially carries out staged excavation of the pile holes, adjusting the stage amplitude accordingly, and simultaneously constructs support structures adapted to the excavation depth and stratum type for each stage, completing the construction of all anti-slide piles in a cyclical manner. This application, by optimizing the excavation sequence and setting stage amplitudes and support structures in stages, adapts to different geological conditions, effectively reducing soil disturbance, lowering the risk of stratum instability, improving the adaptability and construction stability of the support structure, and enhancing the construction quality and safety of the anti-slide piles.

Description

Technical Field

[0001] This application relates to the field of roadbed construction technology, specifically to a method for staged trench excavation and support construction of roadbed anti-slide piles. Background Technology

[0002] Roadbed anti-slide piles fall under the category of geotechnical engineering foundation support. They are a commonly used construction technique for reinforcing roadbed slopes against sliding and ensuring the stability of roadbed foundations, and are widely applied in various roadbed foundation projects. Traditional anti-slide pile excavation and support construction mostly adopts conventional continuous excavation methods. Excavation operations easily cause concentrated disturbance to the soil around the piles, and it is difficult to achieve synchronous connection between excavation and support construction. This can easily lead to problems such as soil instability and slippage in the borehole wall, affecting the continuity of anti-slide pile foundation construction and weakening the overall anti-slide protection effect of the anti-slide piles. It cannot meet the stability and reliability requirements of roadbed foundation construction under complex working conditions. Summary of the Invention

[0003] In order to solve or at least partially solve the above-mentioned technical problems, this application provides a method for the staged excavation and support construction of roadbed anti-slide piles.

[0004] This application provides a method for staged excavation and support construction of roadbed anti-slide piles, including the following steps:

[0005] S1. Based on the distribution characteristics of the anti-slide pile group and the geological distribution data of the pile location area, determine the adjustment rules for the skip excavation sequence and the staged excavation range, wherein the adjustment rules correspond to the stratum type;

[0006] S2. Perform staged excavation of pile holes according to the aforementioned trench excavation sequence, and adjust the staged excavation range according to the aforementioned adjustment rules based on the real-time exposed stratum type.

[0007] S3. After each stage of pile hole excavation is completed, a support structure that is compatible with the current cumulative excavation depth and the type of stratum exposed in real time shall be constructed simultaneously.

[0008] S4. After completing the staged excavation and corresponding support construction of all single pile holes, repeat S2 to S3 to complete the construction of all anti-slide piles.

[0009] Optionally, the excavation sequence is determined based on the distribution characteristics of the pile group, with single-row piles excavated at intervals and pile groups excavated diagonally alternately.

[0010] The construction sequence interval between adjacent anti-slide piles is greater than the interval threshold.

[0011] Optionally, the anti-slide piles include test piles and main piles, and the excavation sequence of the skip-slope trench is as follows:

[0012] Complete the staged excavation and support construction of the test piles;

[0013] The adjustment rule for the staged excavation range is corrected by using the stratum type revealed in real time during the excavation of the test piles;

[0014] The staged excavation and support construction of the main piles are carried out based on the revised adjustment rules.

[0015] Optionally, the adjustment rule for the staged excavation amplitude is:

[0016] For the stable stratum type, the step excavation range adopts the first step range;

[0017] For the geological strata type that is loose, broken, or water-rich, the step-by-step excavation range adopts the second step-by-step range;

[0018] The second step amplitude is smaller than the first step amplitude.

[0019] Optionally, the construction rules for the support structure adapted to the current cumulative excavation depth and the type of strata revealed in real time are as follows:

[0020] Corresponding to the stable stratum type, the support structure adopts a basic retaining wall structure;

[0021] When the strata are loose, broken, or water-rich, or when the current cumulative excavation depth exceeds the depth threshold, the support structure adopts an enhanced retaining wall structure with added reinforcing mesh.

[0022] For the extremely unstable geological formation type, the support structure adopts a composite support structure combining a retaining wall and an isolation and protection layer.

[0023] Optionally, during the staged excavation of pile holes, when water-rich strata are exposed, corresponding dewatering methods are adopted according to the degree of water abundance of the strata, specifically including:

[0024] When the water abundance of the stratum is below the water abundance threshold, the water is collected and discharged through the well.

[0025] When the water content of the stratum reaches or exceeds the water content threshold, a multi-pile-hole dewatering method is used to lower the groundwater level below the current excavation surface.

[0026] Optionally, during the staged excavation of the pile holes, when the aforementioned strata type of quicksand or silt is exposed, corresponding excavation and support methods are adopted, specifically including:

[0027] The borehole wall of the corresponding pile hole is wrapped with an isolation and protective structure;

[0028] The stepped excavation range adopts a third stepped range, which is smaller than the second stepped range;

[0029] After each stage of pile hole excavation is completed, the corresponding support structure is constructed simultaneously.

[0030] Optionally, during the staged excavation of pile holes, when the geological strata type of karst caves or fractured rock layers are exposed, corresponding treatment and support methods are adopted, specifically including:

[0031] For karst caves without filling material, the composite support structure is constructed after being densely filled with filling material.

[0032] For karst caves or fractured rock strata with filling material, the loose filling material is first removed, then reinforced and filled, and then the reinforced wall structure or the composite support structure is constructed according to the stability of the strata.

[0033] Optionally, during the staged excavation and support construction of the pile hole, the method further includes adjusting the ventilation mode according to the current cumulative excavation depth, specifically including:

[0034] When the current cumulative excavation depth is lower than the depth threshold, natural ventilation is used.

[0035] When the current cumulative excavation depth reaches or exceeds the depth threshold, forced ventilation is used to continuously replace the air in the pile hole.

[0036] Optionally, during the staged excavation and support construction of the pile hole, the method further includes simultaneous gas monitoring, specifically including:

[0037] The concentration of toxic and harmful gases inside the pile hole is monitored in real time. When the gas concentration exceeds the concentration threshold, an early warning is triggered and the ventilation intensity is increased.

[0038] The method provided in this application has the following beneficial effects:

[0039] This application optimizes the excavation and support coordination of roadbed anti-slide piles by first determining the excavation sequence and step-by-step amplitude adjustment rules based on the pile group distribution characteristics and geological data, then carrying out step-by-step excavation and synchronously adapting the support structure step by step, and finally completing the entire anti-slide pile construction process in a cyclical manner. This effectively improves the problems of disordered soil disturbance and disconnect between support and working conditions in traditional construction, and enhances the overall stability of the pile hole construction process. Compared with conventional construction methods, this scheme achieves synchronous connection between excavation and support, avoids prolonged unprotected exposure of the pile hole soil, reduces the risk of soil instability and slippage of the hole wall, and broadens the applicability of the scheme by adjusting construction parameters based on different strata conditions, making it suitable for the construction needs of roadbed anti-slide pile foundations in various complex strata.

[0040] By combining the sequential optimization design of the skip-slot excavation, a method of single-row pile intermittent excavation and diagonal alternating excavation of pile groups is adopted. Simultaneously controlling the construction interval of adjacent piles avoids the superimposed soil disturbance caused by the simultaneous construction of adjacent anti-slide piles, reduces stress concentration in the soil around the piles, further stabilizes the soil structure around the piles, and effectively reduces the probability of deformation of the surrounding strata during construction. By constructing test piles first and then revising the staged excavation rules before constructing the main piles, the actual stratum conditions can be determined in advance, allowing the construction parameters of the subsequent main piles to better match the actual site conditions, avoiding construction deviations caused by blind construction, and improving the accuracy of staged excavation and support construction. The staged range is set according to different strata, and the staged range is further reduced for special adverse strata, which can match the inherent stability capacity of various strata, shorten the exposure time of weak soil strata, and reduce soil relaxation deformation. A graded and adaptable support structure, selected based on excavation depth and geological type, ensures that the load-bearing capacity of the support structure matches the operational requirements, avoiding protection failures caused by improper selection and enhancing the overall strength and deformation resistance of the retaining wall structure. For adverse geological conditions such as water-rich areas, quicksand and silt deposits, and karst caves with fractured rock layers, corresponding treatment methods are employed to specifically resolve construction obstacles caused by various geological defects, ensuring the quality of pile hole formation and improving the foundation construction quality of anti-slide piles. Combining ventilation methods with construction depth-appropriate design and simultaneous gas monitoring optimizes the internal construction environment of the pile holes, reduces safety hazards during construction, ensures the safety and reliability of anti-slide pile construction, and ultimately improves the overall anti-slide protection performance of the anti-slide piles, better fulfilling their role in roadbed foundation support. Attached Figure Description

[0041] Figure 1 A schematic diagram of a construction method for staged trench excavation and support of roadbed anti-slide piles provided in this application embodiment;

[0042] Figure 2 This is a schematic diagram of a skip-slot excavation sequence provided in an embodiment of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application will be described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely for explaining this application and not for limiting it. It should also be noted that, for ease of description, only the parts relevant to this application are shown in the drawings, not all of them. Before discussing exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts describe operations (or steps) as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. Furthermore, the order of the operations can be rearranged. The process can be terminated when its operation is completed, but may also have additional steps not included in the drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0044] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0045] See Figure 1 This application provides a method for staged excavation and support construction of roadbed anti-slide piles, including the following steps:

[0046] S1. Based on the distribution characteristics of the anti-slide pile group and the geological distribution data of the pile location area, determine the adjustment rules for the skip excavation sequence and the staged excavation range, and the adjustment rules correspond to the stratum type.

[0047] S2. The pile holes are excavated in stages according to the order of the trench excavation, and the excavation range is adjusted according to the real-time exposed stratum type and adjustment rules.

[0048] S3. After each stage of pile hole excavation is completed, a support structure that is compatible with the current cumulative excavation depth and the type of strata exposed in real time shall be constructed simultaneously.

[0049] S4. After completing the staged excavation and corresponding support construction of all single pile holes, repeat S2 to S3 to complete the construction of all anti-slide piles.

[0050] Staged excavation and support construction is a construction method for anti-slide pile construction in roadbeds. It involves staggering the excavation sequence of individual piles, dividing the excavation work into segments, and simultaneously matching the support work. This method is suitable for pile construction in roadbed slope anti-slide reinforcement projects. In roadbed slope engineering, the pile location area often exhibits uneven soil distribution and varying soil stability. Conventional anti-slide pile construction often employs continuous excavation and whole-segment excavation, which can easily lead to problems such as excessive soil disturbance, mutual interference between adjacent pile construction, mismatch between excavation segments and actual soil stability, and untimely coordination between support and excavation operations. These issues not only cause imbalance in the stress state of the soil between piles but also easily lead to instability and collapse of the borehole wall soil, directly affecting the quality of pile hole formation and the overall stability of the construction process.

[0051] When constructing anti-slide piles for roadbeds, the first step is to determine the excavation sequence and adjustment rules for staged excavation based on the pile group distribution characteristics and geological distribution data of the pile location area. These adjustment rules correspond to the soil strata type. The pile group distribution characteristics determine the spatial relationship between the piles, and the geological distribution data of the pile location area reflects the foundation conditions of the soil strata within the pile construction area. The operational rules determined based on this correspond well to the actual engineering conditions of the construction area. Staged excavation of the pile holes is carried out according to the determined excavation sequence. During excavation, the staged excavation range is adjusted according to the real-time revealed soil strata type and the pre-established adjustment rules. The real-time revealed soil strata type reflects the actual soil conditions within the pile hole construction area, providing a corresponding verification with the preliminary survey data. By adjusting the staged excavation range in real time, the operational range of a single excavation can be adapted to the actual stability state of the soil strata. After each stage of pile hole excavation is completed, a support structure adapted to the current cumulative excavation depth and the type of strata exposed in real time is constructed simultaneously. Timely construction of the corresponding support structure after each excavation minimizes the exposure time of the soil after excavation, preventing stress relaxation and strength reduction due to prolonged exposure. Once all staged excavation and corresponding support construction for a single pile hole are completed, the staged excavation, amplitude adjustment, and corresponding support construction are repeated until all anti-slide piles are constructed.

[0052] This construction method can effectively reduce the disturbance range of the surrounding soil caused by pile excavation, avoid mutual influence during the construction of adjacent piles, maintain the original stress state of the soil between piles, match the excavation segments with the actual stratum conditions, and ensure close connection between support and excavation operations. It provides continuous and stable support for the pile hole wall, reduces the risk of hole wall instability and collapse during pile hole construction, and improves the quality of pile hole formation and the overall stability of the construction process. It can not only reduce the damage to the original soil structure of the roadbed slope during construction, but also adapt to the construction needs of anti-slide piles under different stratum conditions, and ensure the anti-slide reinforcement effect after the anti-slide piles are completed.

[0053] In some implementations, the excavation sequence is determined based on the distribution characteristics of the pile group; single-row piles are excavated at intervals, while pile groups are excavated diagonally alternately.

[0054] The construction sequence interval between adjacent anti-slide piles is greater than the interval threshold.

[0055] The determination of the excavation sequence is based on the distribution characteristics of the anti-slide pile group. The distribution characteristics of the pile group determine the spatial relationship between the piles and the scope of construction impact. Based on this, the corresponding excavation method is matched to minimize the concentrated disturbance of the surrounding soil caused by the excavation operation.

[0056] Specifically, for single-row anti-slide piles, the piles are linearly and continuously distributed, and the construction impact areas of adjacent piles overlap. An intermittent excavation method is used to stagger the excavation sequence of adjacent piles, avoiding simultaneous disturbance of the soil within the same linear section and reducing continuous stress and deformation of the soil between piles. For multi-row, multi-column pile groups, the construction impact areas of the piles overlap. A diagonal alternating excavation method is used, with work carried out alternately on piles at diagonal positions, dispersing the impact of excavation on the soil and avoiding concentrated and superimposed disturbances in the same area. For example... Figure 2 The diagram shows the sequence of excavation steps, with straight lines used to distinguish between different sections. Figure 2 Figures (a) and (b) are shown in the diagram. Figure (a) corresponds to a single row of piles, while Figure (b) corresponds to a group of piles. The numbers in the diagrams represent the excavation sequence, from smallest to largest.

[0057] The construction sequence interval between adjacent anti-slide piles is greater than the interval threshold. By controlling the duration of the work interval, the soil around the piles that are completed first is allowed to undergo stress redistribution. Once the soil condition stabilizes, excavation work on adjacent piles is then carried out, avoiding mutual interference during the construction of adjacent piles. This excavation method can effectively disperse the soil disturbance range, maintain the original stable state of the soil between piles, reduce the risk of soil deformation and instability during construction, and adapt to the construction needs of anti-slide pile groups with different layouts.

[0058] In some implementations, the anti-slide piles include test piles and main piles, and the excavation sequence is as follows:

[0059] Complete the staged excavation and support construction of the test piles;

[0060] The adjustment rules for the staged excavation range are revised based on the stratum types revealed in real time during the test pile excavation process.

[0061] The staged excavation and support construction of the main piles are carried out based on the revised adjustment rules.

[0062] In the construction of anti-slide piles for roadbeds, test piles are preliminary piles used to verify the actual geological distribution in the pile location area and adjust construction parameters, while main piles are the main piles used to achieve the anti-slide reinforcement function of the roadbed slope. By constructing test piles in advance, the actual geological conditions of the construction area can be understood in advance, construction parameters can be corrected, and the roadbed construction scenario with fluctuating geological conditions can be adapted.

[0063] When constructing anti-slide piles, the staged excavation and support construction of test piles are completed first. During the excavation of test piles, the actual stratum type within the pile construction area can be revealed in real time, corresponding to and verifying the geological distribution data obtained in the previous survey, thus clarifying the actual stability state of different strata. Based on the actual stratum information obtained during the test pile construction, the adjustment rules for the staged excavation range are revised to better match the actual stratum conditions of the construction area. After the adjustment rules are revised, the staged excavation and support construction of the main piles is carried out based on the revised rules.

[0064] This construction method effectively avoids the mismatch between construction parameters caused by deviations between preliminary survey data and actual site conditions, improves the matching degree between the staged excavation range and the actual stability state of the strata, reduces unnecessary disturbance to the soil during excavation, and lowers the risk of pile hole instability and collapse. Simultaneously, the test piles constructed first verify the adaptability of the construction process, ensuring the stability of the subsequent main pile construction process, and improving the overall construction quality and the reinforcement effect after pile completion.

[0065] In some implementations, the adjustment rules for the staged excavation amplitude are as follows:

[0066] For stable geological formations, the first stage of excavation is adopted.

[0067] For loose, broken, or water-rich strata, the second stage excavation stage should be adopted.

[0068] The amplitude of the second sub-order is smaller than that of the first sub-order.

[0069] The stepped excavation depth refers to the vertical working depth of a single-stage pile hole excavation. Its value is related to the soil disturbance range and soil exposure time of a single excavation operation, and is associated with the stability state of the stratum itself. The adjustment rules for the stepped excavation depth are based on the soil self-stabilizing capacity corresponding to the stratum type, and balance the work efficiency and safety stability of the construction process through a graded matching method.

[0070] For stable strata with good soil integrity and strong self-stabilizing ability, soil deformation and collapse are less likely to occur after excavation. The first-stage excavation amplitude is adopted. The first-stage amplitude corresponds to a greater vertical working depth per excavation, which can reduce the number of excavation segments for a single pile while ensuring the safety of pile hole operations, thus improving overall construction efficiency. For loose, broken, or water-rich strata with poor soil integrity and weak self-stabilizing ability, soil loosening, deformation, and even collapse and water inrush are more likely to occur after excavation. The second-stage excavation amplitude is adopted, which is smaller than the first-stage amplitude. The second-stage amplitude corresponds to a smaller vertical working depth per excavation, which can quickly complete single-stage excavation operations, significantly shorten the soil exposure time, and reduce the risk of soil instability during excavation.

[0071] This tiered adjustment method allows the tiered excavation range to be adapted to the actual stability of the strata, avoiding both safety hazards caused by excessive single excavation depth and reduced work efficiency caused by indiscriminately reducing the excavation depth, thus adapting to the needs of anti-slide pile excavation under different strata conditions.

[0072] In some implementation methods, the construction rules for the support structure, which are adapted to the current cumulative excavation depth and the type of strata revealed in real time, are as follows:

[0073] For stable geological formations, the support structure adopts a foundation retaining wall structure;

[0074] For loose, broken, or water-rich strata, or when the current cumulative excavation depth exceeds the depth threshold, the support structure adopts an enhanced retaining wall structure with added reinforcing mesh.

[0075] For extremely unstable geological formations, a composite support structure combining retaining wall and isolation protection layer is adopted.

[0076] The support structure is a structure that provides support and constraint to the soil wall during the excavation of pile holes, preventing soil deformation and collapse. Its support strength must be matched with the stability of the strata and the cumulative excavation depth of the pile hole, so as to avoid the risk of hole wall instability caused by insufficient support strength, and also to avoid unnecessary cost investment caused by indiscriminate reinforcement of support.

[0077] For stable strata, the soil itself has good integrity and strong self-stabilizing ability. After the pile hole is excavated, the hole wall is not easy to deform and collapse. The support structure adopts a foundation wall protection structure to provide basic constraint support for the hole wall soil, which is adapted to the stable state of the strata itself and meets the support requirements of conventional construction process.

[0078] For loose, fractured, or water-rich strata, where the soil itself has poor integrity and weak self-stabilizing ability, or when the cumulative excavation depth of the pile hole exceeds the depth threshold, the lateral pressure on the soil wall increases, significantly raising the risk of deformation and instability. In such cases, a reinforced retaining wall structure with added reinforcing mesh is adopted. The reinforcing mesh enhances the overall stiffness and deformation resistance of the retaining structure, providing stronger support and constraint to the soil wall, offsetting the increased lateral earth pressure, and ensuring the stability of the hole wall during excavation.

[0079] For extremely unstable strata, the soil is prone to collapse and flow. A single retaining wall structure alone cannot meet the support requirements. The support structure adopts a composite support structure that combines retaining wall and isolation protection layer. First, the isolation protection layer seals the soil in the borehole wall to prevent soil loss and collapse. Then, the retaining wall structure provides continuous and stable support, thus doubly ensuring the safety of the pile hole construction process.

[0080] This adaptation method allows the support strength to correspond to the actual risk level during construction, optimizing the cost and efficiency of support operations while ensuring construction safety, and adapting to the construction needs of anti-slide pile support under different geological conditions and excavation depths.

[0081] In some implementations, during the staged excavation of pile holes, when water-rich strata are exposed, corresponding dewatering methods are adopted according to the degree of water abundance in the strata, specifically including:

[0082] When the water abundance of the stratum is below the water abundance threshold, the water is collected and discharged through the well.

[0083] When the water content of the stratum reaches or exceeds the water content threshold, a multi-pile dewatering method is used to lower the groundwater level below the current excavation surface.

[0084] During the excavation of pile holes, when water-rich strata are exposed, groundwater will continuously seep into the pile hole, softening the soil of the hole wall and significantly reducing the soil's self-stabilizing ability. At the same time, it will interfere with the normal progress of excavation operations, and in severe cases, it may cause the hole wall to collapse and water and sand to surge in. It is necessary to match the appropriate dewatering method according to the water-richness of the strata to ensure the stability and safety of the construction process.

[0085] Specifically, when the water-rich strata are below the water-rich threshold, the groundwater seepage is small, and its softening effect on the borehole wall soil is limited. In this case, a borehole-based water collection and drainage method can be used to collect and drain the groundwater that has seeped into the borehole, quickly reducing the water level inside the borehole and preventing prolonged soaking of the borehole wall soil, thus ensuring the smooth progress of single-stage excavation. However, when the water-rich strata reach or exceed the water-rich threshold, the groundwater seepage is large, and continuous groundwater recharge will continuously soften the borehole wall and surrounding soil. Relying solely on borehole-based water collection and drainage cannot eliminate the negative impact of groundwater on construction. In this case, a multi-bore dewatering method can be used to lower the overall groundwater level in the construction area below the current excavation face, fundamentally reducing groundwater seepage into the borehole, preventing continuous softening of the borehole wall soil, and significantly reducing the risk of water inrush and borehole wall instability.

[0086] This graded and matched precipitation method can be adapted to geological conditions with different water-rich levels. It avoids the safety hazards of a single precipitation method being unable to cope with highly water-rich strata, and also avoids the increased operating costs caused by indiscriminate use of large-scale precipitation. It balances construction safety and operational efficiency, and adapts to the needs of anti-slide pile excavation construction under different water-rich conditions.

[0087] In some implementations, when quicksand or silty strata are exposed during the staged excavation of pile holes, corresponding excavation and support methods are adopted, specifically including:

[0088] The borehole wall of the corresponding pile hole is wrapped with an isolation and protective structure;

[0089] The staged excavation amplitude adopts the third stage amplitude, which is smaller than the second stage amplitude.

[0090] After each stage of pile hole excavation is completed, the corresponding support structure is constructed simultaneously.

[0091] For quicksand or silty strata, the soil itself has no cohesion, high fluidity, and extremely poor self-stabilization ability. During the excavation of pile holes, soil loss, hole wall collapse, and sand inrush are very likely to occur. This is a high-risk condition in the construction of roadbed anti-slide piles. A special excavation and support method can be matched to suppress the safety risks during the construction process.

[0092] Specifically, during the staged excavation of pile holes, when quicksand or silt strata are exposed, an isolation and protective structure is first used to wrap the hole wall. This structure seals off the easily flowing soil, blocks channels for soil loss, and prevents soil collapse and sand inrush during excavation, providing a stable foundation for subsequent excavation. For quicksand or silt strata, the staged excavation depth is the third stage, smaller than the second stage for loose, fractured, or water-rich strata. This further reduces the vertical working depth of a single excavation, minimizing the duration of soil exposure and reducing disturbance to highly unstable soil, thus preventing increased soil fluidity due to excavation disturbance. Upon completion of each stage of pile hole excavation, the corresponding support structure is simultaneously constructed, ensuring seamless integration between excavation and support work. This quickly provides stable support and constraint to the hole wall soil, locking in its stable state.

[0093] This construction method can specifically address the problems of poor self-stability and easy flow and loss of quicksand and silt strata. It controls construction risks from three aspects: soil sealing, disturbance control, and rapid support, significantly reducing the probability of borehole wall collapse and sand inrush, and ensuring the safety and quality of anti-slide pile construction under extremely unstable strata conditions.

[0094] In some implementations, when karst caves or fractured rock strata are exposed during the staged excavation of pile holes, corresponding treatment and support methods are adopted, specifically including:

[0095] For karst caves without filling materials, a composite support structure is constructed after dense filling with filling materials.

[0096] For karst caves or fractured rock strata with filling material, first remove the loose filling material, then reinforce and fill it, and then construct a reinforced wall structure or composite support structure according to the stability of the strata.

[0097] For strata with karst caves or fractured rock layers, there are problems such as lack of rock mass integrity and discontinuous structure. During the excavation of pile holes, the free face is prone to collapse, loss of filling material, and uneven stress on the hole wall, which directly affects the quality of pile hole formation and construction safety. Appropriate stratum treatment and support methods can be matched to eliminate safety hazards during construction.

[0098] Specifically, during the staged excavation of pile holes, when encountering karst caves or fractured rock formations, corresponding treatment and support methods can be adopted based on the actual filling condition and degree of fracture of the strata. For karst caves without filling material, the cavities are densely filled with filling materials, followed by the construction of a composite support structure. Dense filling fills the cavity structure of the karst cave, restores the continuity of the surrounding rock mass, eliminates the risk of collapse at the free face, and then the composite support structure provides continuous and stable support and constraint to the borehole wall, ensuring the safe advancement of pile hole operations. For karst caves or fractured rock formations with filling material, the loose filling material is first removed, and then the cleaned cavities and fractured areas are reinforced and filled. After filling and reinforcement, a reinforced retaining wall structure or a composite support structure is constructed based on the stability of the treated strata. Removing loose filling material eliminates unstable bodies that are prone to collapse and loss, while reinforcement and filling restore the integrity and bearing capacity of the rock mass. Finally, a support structure of the corresponding level is matched to achieve the adaptation of support strength to the actual state of the strata.

[0099] This treatment method can specifically address the problems of discontinuous and unstable geological structures such as karst caves and fractured rock strata, eliminating the risk of structural instability during pile hole excavation from the root, ensuring the forming quality and construction safety of pile holes under special geological conditions, and adapting to the construction needs of roadbed anti-slide piles under complex geological conditions.

[0100] In some implementations, during the staged excavation and support construction of the pile hole, the method also includes adjusting the ventilation method according to the current cumulative excavation depth, specifically including:

[0101] When the current cumulative excavation depth is below the depth threshold, natural ventilation is used;

[0102] When the current cumulative excavation depth reaches or exceeds the depth threshold, forced ventilation is used to continuously replace the air in the pile hole.

[0103] During pile hole excavation, as the cumulative excavation depth increases, the air circulation path between the inside and outside of the pile hole continues to lengthen, and the air circulation resistance increases continuously. This can easily lead to poor air circulation, insufficient oxygen content, and accumulation of polluted air, directly affecting the safety and stability of the working environment. The appropriate ventilation method can be matched according to the current cumulative excavation depth of the pile hole to ensure environmental safety during construction.

[0104] Specifically, when the current cumulative excavation depth of the pile hole is below the depth threshold, the natural airflow path inside and outside the pile hole is short, and the flow resistance is small. Smooth air exchange between the inside and outside of the pile hole can be achieved solely through natural pressure difference, meeting the air quality requirements during construction. Natural ventilation can maintain a stable air environment inside the pile hole without the need for additional operating equipment. However, when the current cumulative excavation depth of the pile hole reaches or exceeds the depth threshold, the natural airflow capacity inside and outside the pile hole decreases significantly. Natural ventilation alone cannot achieve effective air exchange, easily leading to insufficient oxygen content and the inability to promptly remove polluted gases. In this case, forced ventilation is used to continuously replace the air inside the pile hole. Through continuous air circulation, sufficient oxygen content inside the pile hole is ensured, and polluted gases generated during construction are promptly removed, maintaining a safe and compliant working environment.

[0105] This graded and adaptable ventilation method can adapt to the air replacement needs at different excavation depths. It avoids the cost and energy waste caused by adding additional ventilation devices in shallow working conditions, and also eliminates the safety hazards caused by insufficient natural ventilation in deep working conditions. It takes into account both the economy and safety of the construction process and adapts to the construction needs of roadbed anti-slide piles at different excavation depths.

[0106] In some implementations, the method further includes simultaneous gas monitoring during the staged excavation and support construction of the pile hole, specifically including:

[0107] The concentration of toxic and harmful gases inside the pile hole is monitored in real time. When the gas concentration exceeds the concentration threshold, an early warning is triggered and the ventilation intensity is increased.

[0108] During the staged excavation and support construction of pile holes, some strata may contain toxic and harmful gases. The excavation operation will break the original closed state of the strata, releasing these toxic and harmful gases into the pile hole. As the excavation depth increases, the air circulation capacity inside the pile hole decreases, making it easy for toxic and harmful gases to accumulate and exceed the concentration limit, directly threatening the safety and stability of the working environment. Therefore, gas monitoring is implemented simultaneously throughout the construction process to achieve early identification and rapid handling of risks.

[0109] Specifically, throughout the entire process of staged excavation and support construction of the pile hole, the concentration of toxic and harmful gases inside the pile hole can be monitored in real time, and gas concentration data inside the pile hole can be continuously collected. When the monitored gas concentration exceeds the concentration threshold, an early warning is triggered, and ventilation intensity is simultaneously increased. By improving air replacement efficiency, the discharge of polluted gases and the replenishment of fresh air inside the pile hole are accelerated, rapidly reducing the concentration of toxic and harmful gases inside the pile hole until the gas concentration drops back to within a safe range, and then the normal construction operation process is resumed.

[0110] This real-time monitoring and control method can promptly detect abnormal gas concentrations within the pile borehole, preventing safety hazards caused by the accumulation of toxic and harmful gases, and enabling early warning and rapid response to construction safety risks. Simultaneously, it can adjust the ventilation intensity based on the actual gas state within the pile borehole, ensuring a safe working environment throughout the construction process while avoiding energy and cost waste caused by indiscriminate, continuous high-intensity ventilation. This adapts to the safety management needs of roadbed anti-slide pile construction under different geological conditions and excavation depths.

[0111] In addition, based on the above-mentioned step-by-step excavation and support construction method for roadbed anti-slide piles, in order to further improve the adaptability of construction parameters to geological conditions and reduce the disturbance to the surrounding soil during construction, it is also possible to further optimize the parameter adjustment logic of the construction process to form a more refined iterative construction method.

[0112] Specifically, during pile group construction, after the test piles are completed and the first revision of the step-by-step excavation range adjustment rules is made, for each main pile completed with step-by-step excavation and support construction, the stratum type and soil stability data revealed during the pile excavation process are simultaneously summarized for iterative optimization of the step-by-step excavation range adjustment rules. Subsequent piles are constructed using the latest iterated adjustment rules to match the step-by-step excavation range and support structure type, achieving continuous adaptation of construction parameters as the pile group construction progresses. The adjustment of the step-by-step excavation range is linked to the construction parameters of the support structure. When the step-by-step excavation range is reduced to the corresponding level, the construction thickness and reinforcement mesh density of the support structure are adjusted simultaneously to ensure a correspondence between the single excavation disturbance range and the support constraint strength, avoiding a mismatch between support strength and excavation disturbance.

[0113] Simultaneously, based on deformation monitoring data of the soil surrounding the already constructed piles, the excavation sequence and construction interval of subsequent piles can be adjusted. When soil deformation exceeds the deformation threshold, the construction interval of adjacent piles can be extended, or the excavation sequence can be adjusted to a region where soil deformation is stable, avoiding the continuous accumulation of soil deformation. This scheme can further improve the level of refined control over the construction process, significantly reduce the probability of mismatch between construction parameters and actual site conditions, further minimize the disturbance to the surrounding soil, improve the stability and pile quality throughout the entire pile group construction process, and form an operational logic that can be continuously optimized as the construction progresses.

[0114] Furthermore, during the construction of test piles, in addition to completing the initial revision of the step-by-step excavation range adjustment rules, the vertical distribution range, thickness, and actual stability of unfavorable strata within the pile construction area can be simultaneously marked, forming an advanced prediction profile of unfavorable strata. During subsequent main pile construction, when the excavation operation advances to the preset advance distance of the unfavorable strata, advanced reinforcement pretreatment is first implemented for that stratum section, with the pretreatment method matching the stratum type. For loose and fractured strata, advanced grouting reinforcement is used to improve the integrity and self-stabilizing capacity of the soil; for water-rich strata, based on advanced dewatering, water-stopping reinforcement of the surrounding soil is implemented simultaneously to block the seepage path of groundwater; for quicksand and silt strata, advanced casing isolation is used to seal the easily flowing soil in advance, preventing soil loss during excavation.

[0115] After completing the pretreatment, excavation operations are carried out according to the stepped excavation range adapted to the stratum type, and the corresponding level of support structure is constructed simultaneously. The parameters of the pretreatment are related to the stepped excavation range; the worse the stratum stability, the larger the vertical coverage of the pretreatment, and the smaller the corresponding stepped excavation range, thus achieving pre-emptive control of construction risks. This scheme advances the risk control of unfavorable strata, reducing the risks of borehole wall instability, sand inrush, and water inrush during excavation. At the same time, the pretreatment range matches the stratum risk level, avoiding the increased costs caused by indiscriminate pretreatment, and balancing construction safety and operational economy.

[0116] In addition, further optimization can be made to address the continuity of stress in the support structure and the impact of pile group construction on the overall stability of the slope, forming a construction method that combines staged support continuous force transmission with dynamic control of slope stability. This will further improve the overall stress performance of the support structure, avoid the risk of overall slope deformation and instability caused by pile group operations in conventional construction, and enhance the overall safety and adaptability of the scheme.

[0117] Specifically, for tiered support structures, the connection method between upper and lower tiers can be optimized. During the construction of each tier, an overlap anchoring structure is reserved at the connection point between the upper and lower tiers. The reinforcing mesh of the upper tier extends downwards to the predetermined overlap length of the lower tier. During the construction of the lower tier, the corresponding reinforcing mesh is anchored and overlapped with the extended mesh of the upper tier, ensuring that the support structure along the entire pile length forms a continuous and complete force-transfer unit. This avoids the problems of joint cracking and soil leakage caused by the disconnection of upper and lower sections and discontinuous stress in conventional tiered retaining walls. Simultaneously, the construction parameters of the support structure are linked to the overall stability of the slope, and the slope deformation and deep soil displacement of the roadbed slope are continuously monitored during construction.

[0118] When the slope deformation exceeds the preset threshold, the staged excavation range of subsequent piles, the grade of the support structure, and the sequence of trench excavation are adjusted simultaneously. This reduces the excavation range per session, increases the constraint strength of the support structure, and adjusts the excavation sequence to the area least affected by slope deformation, avoiding overall slope stress imbalance caused by concentrated pile excavation. For slope deformation-sensitive sections, temporary anchoring structures are added between piles during staged pile excavation to constrain soil deformation. These temporary anchoring structures are removed after all pile construction is completed and soil stress redistribution stabilizes.

[0119] This scheme differs from the conventional construction mode that only focuses on the stability of the single pile hole wall. It combines the stress continuity of the single pile support structure with the overall stability control of the slope, which not only improves the overall deformation resistance of the support structure, but also avoids the negative impact of pile group construction on the overall stability of the roadbed slope from a global perspective. It further strengthens the safety redundancy of the entire construction process and is suitable for the anti-slide pile construction needs of steep slopes and deformation-sensitive sections.

[0120] Alternatively, further optimization can be made to adapt the phased excavation rhythm to the time-dependent characteristics of the support structure, and to control the stress superposition during pile group construction. This can further avoid the risk of support failure caused by the support structure not reaching the design strength before the next stage of excavation is carried out in conventional construction, as well as the stress superposition disturbance problem caused by the concentrated construction of pile groups, thereby improving the safety redundancy and construction quality controllability of the scheme.

[0121] Specifically, after each stage of the support structure is completed, a differentiated curing and resting time can be set according to the type of support structure and the stability state of the corresponding stratum. The next stage of pile hole excavation will only proceed after the actual strength of the support structure reaches the design threshold. Among them, the curing and resting time corresponding to the basic retaining wall structure is the shortest, followed by the reinforced retaining wall structure, and the longest curing and resting time corresponding to the composite support structure. At the same time, the worse the stratum stability, the corresponding curing and resting time will be appropriately extended. Subsequent excavation operations will only be carried out after confirming that the support structure has fully hardened and has complete restraint bearing capacity, so as to avoid the problem of cracking, deformation or even failure of the support structure due to excavation disturbance before it has reached the required strength.

[0122] Meanwhile, based on the spatial distribution of the anti-slide pile group and the stress characteristics of the roadbed slope, multiple independent construction zones can be defined. Within each zone, piles are excavated alternately in a staggered manner to avoid simultaneous excavation of multiple piles in the same slope section at the same time. This disperses the stress disturbance to the slope soil from a spatiotemporal perspective, preventing overall slope deformation caused by the superposition of stress releases from multiple excavation faces. The construction progress of each zone is dynamically linked to slope soil deformation monitoring data. When the soil deformation in a certain zone approaches a preset threshold, excavation work in that zone is suspended, and construction is transferred to a zone with no deformation risk. Work in the corresponding zone resumes only after the soil stress redistribution is complete and the deformation state stabilizes.

[0123] This scheme differs from the conventional fixed excavation rhythm and indiscriminate construction mode. It binds the strength and time-dependent characteristics of the support structure to the excavation rhythm, and at the same time realizes the decentralized control of stress disturbance during pile group construction from a global perspective. This not only ensures the effectiveness of the single pile support structure, but also avoids the negative impact of pile group construction on the overall stability of the slope, further improving the safety and controllability of the entire construction process, and adapting to the construction needs of anti-slide pile groups under high and steep slopes and complex strata conditions.

[0124] Finally, further optimizations can be made to the real-time dynamic control of soil stress in the pile hole wall and the mutual adaptation between temporary support structures and permanent piles. This will further avoid the risk of instability caused by the delayed response to changes in soil stress in the hole wall during conventional construction, while reducing material waste in temporary support and improving the economic efficiency and the level of refined control of construction safety.

[0125] Specifically, during the staged excavation of each pile, stress monitoring elements can be deployed at different vertical depths of the borehole wall soil to collect real-time data on lateral earth pressure, stress release, and deformation rate of the borehole wall soil. This allows for a real-time quantitative assessment of the borehole wall soil stability, supplementing conventional control methods that rely solely on qualitative judgments based on stratum type. The monitoring data is linked in real-time with the staged excavation amplitude and support structure construction parameters. When the monitored soil stress release exceeds a preset threshold and an accelerating deformation trend appears, the current stage of excavation is stopped, the next stage of staged excavation amplitude is simultaneously reduced, the corresponding support structure is upgraded, and stronger support constraints are applied in advance to block the path of continuous soil stress release and prevent borehole wall instability caused by continuous soil deformation.

[0126] To optimize the temporary support structure and permanent piles, the layout and material selection of the support structure can be adjusted. This allows the staged support structure to serve as the outer protective layer of the permanent anti-sliding piles, forming a complete load-bearing unit with the subsequently poured pile concrete. Specifically, the reinforcing mesh within the reinforced wall structure is designed with pre-reserved anchorage lap lengths for the main reinforcement bars of the pile. During the subsequent installation of the pile reinforcement cage, the main reinforcement bars are anchored to the pre-reserved mesh, enabling the load-bearing reinforcement of the temporary support structure to participate in the load-bearing capacity of the permanent pile. This eliminates the need for additional removal of the temporary support structure and avoids the material waste associated with conventional temporary supports that only serve a construction period and are discarded after pile completion. Furthermore, the skip-excavation sequence can be linked to borehole stress monitoring data. When abnormal soil stress is detected during the excavation of a certain pile location, the excavation sequence of adjacent piles is adjusted synchronously to avoid the superposition of stress disturbances from adjacent pile excavations, further controlling construction risks.

[0127] This approach differs from conventional construction methods that rely solely on preliminary surveys and qualitative assessments of geological strata. By monitoring the stress in the borehole wall soil in real time, it enables real-time response to construction parameters. Simultaneously, it achieves coordinated stress distribution between temporary support and permanent piles, thereby improving the real-time nature and accuracy of construction safety management, significantly reducing material consumption for temporary support, and balancing construction safety, pile quality, and project economy. It is suitable for the construction needs of anti-slide piles in roadbeds under various geological conditions.

[0128] The above description is merely a preferred embodiment and the technical principles employed in this application. This application is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions that can be made by those skilled in the art will not depart from the scope of protection of this application. Therefore, although this application has been described in detail through the above embodiments, this application is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of this application.

Claims

1. A method for staged excavation and support construction of roadbed anti-slide piles, characterized in that, Anti-slide piles include test piles and main piles, and the method includes the following steps: S1. Based on the distribution characteristics of the anti-slide pile group and the geological distribution data of the pile location area, determine the adjustment rules for the skip excavation sequence and the staged excavation range. The adjustment rules correspond to the stratum type. At the same time, divide the pile group into multiple independent construction zones according to the spatial distribution of the pile group. S2. First, construct test piles. Based on the stratum type revealed in real time during the test pile excavation, correct the adjustment rules for the staged excavation range. At the same time, mark the vertical distribution range and thickness of the unfavorable stratum. Then, according to the skip-slot excavation sequence, staggered and alternately excavate the pile holes in each construction zone. When excavating to the preset advance distance of the unfavorable stratum, first implement the advance reinforcement pretreatment that matches the stratum type. Then, adjust the staged excavation range according to the adjustment rules based on the stratum type revealed in real time. S3. After each stage of pile hole excavation is completed, a support structure that is compatible with the current cumulative excavation depth and the type of stratum exposed in real time is constructed simultaneously. The next stage of pile hole excavation is carried out after the actual strength of the support structure reaches the design threshold. S4. After completing the staged excavation and corresponding support construction of all single pile holes, repeat S2 to S3 to complete the construction of all anti-slide piles.

2. The method according to claim 1, characterized in that, The excavation sequence is determined based on the distribution characteristics of the pile group. Single-row piles are excavated at intervals, while pile groups are excavated diagonally alternately. The construction sequence interval between adjacent anti-slide piles is greater than the interval threshold.

3. The method according to claim 1, characterized in that, The excavation sequence for the skip-slot excavation is as follows: Complete the staged excavation and support construction of the test piles; The adjustment rule for the staged excavation range is corrected by using the stratum type revealed in real time during the excavation of the test piles; The staged excavation and support construction of the main piles are carried out based on the revised adjustment rules.

4. The method according to claim 1, characterized in that, The adjustment rule for the staged excavation range is as follows: For the stable stratum type, the step excavation range adopts the first step range; For the geological strata type that is loose, broken, or water-rich, the step-by-step excavation range adopts the second step-by-step range; The second step amplitude is smaller than the first step amplitude.

5. The method according to claim 1, characterized in that, The construction rules for the support structure that are compatible with the current cumulative excavation depth and the type of strata revealed in real time are as follows: Corresponding to the stable stratum type, the support structure adopts a basic retaining wall structure; When the strata are loose, broken, or water-rich, or when the current cumulative excavation depth exceeds the depth threshold, the support structure adopts an enhanced retaining wall structure with added reinforcing mesh. For the extremely unstable geological formation type, the support structure adopts a composite support structure combining a retaining wall and an isolation and protection layer.

6. The method according to claim 1, characterized in that, During the staged excavation of pile holes, when water-rich strata are exposed, corresponding dewatering methods are adopted according to the degree of water abundance of the strata, specifically including: When the water abundance of the stratum is below the water abundance threshold, the water is collected and discharged through the well. When the water content of the stratum reaches or exceeds the water content threshold, a multi-pile dewatering method is used to lower the groundwater level below the current excavation face.

7. The method according to claim 4, characterized in that, During the staged excavation of pile holes, when the aforementioned strata of quicksand or silt are exposed, corresponding excavation and support methods are adopted, specifically including: The borehole wall of the corresponding pile hole is wrapped with an isolation and protective structure; The stepped excavation range adopts a third stepped range, which is smaller than the second stepped range; After each stage of pile hole excavation is completed, the corresponding support structure is constructed simultaneously.

8. The method according to claim 5, characterized in that, During the staged excavation of pile holes, when the geological strata type, such as karst caves or fractured rock layers, are exposed, corresponding treatment and support methods are adopted, specifically including: For karst caves without filling material, the composite support structure is constructed after being densely filled with filling material. For karst caves or fractured rock strata with filling material, the loose filling material is first removed, then reinforced and filled, and then the reinforced wall structure or the composite support structure is constructed according to the stability of the strata.

9. The method according to claim 5, characterized in that, During the staged excavation and support construction of the pile hole, the method also includes adjusting the ventilation mode according to the current cumulative excavation depth, specifically including: When the current cumulative excavation depth is lower than the depth threshold, natural ventilation is used. When the current cumulative excavation depth reaches or exceeds the depth threshold, forced ventilation is used to continuously replace the air in the pile hole.

10. The method according to claim 9, characterized in that, During the staged excavation and support construction of pile holes, the method also includes simultaneous gas monitoring, specifically including: The concentration of toxic and harmful gases inside the pile hole is monitored in real time. When the gas concentration exceeds the concentration threshold, an early warning is triggered and the ventilation intensity is increased.

Images