A complex rubble interlayer stratum lime-soil compaction pile anti-collapse precise hole-forming construction method

Abstract

The present application relates to the technical field of foundation treatment construction, and discloses a complex gravel interlayer stratum lime-soil compaction pile anti-collapse precise hole-forming construction method, which comprises the following steps: determining target piles and peripheral design piles according to pile position information and stratum information, and establishing a self-enclosing construction unit; dividing the peripheral design piles into multiple construction batches and completing hole-forming and filler tamping for each pile; forming a reinforced tamping section corresponding to the gravel interlayer depth in the peripheral design piles; detecting the state of the inter-pile soil corresponding to the gravel interlayer depth between adjacent peripheral design piles, opening the target pile construction after forming a circumferential effective constraint section meeting the requirements; drilling and processing the target piles; taking the completed target piles as reusable peripheral piles of the next construction unit, and forming a shared constraint side by using the completed design piles, and continuing the construction after supplementing the remaining peripheral design piles. The present application can improve the hole wall stability, hole-forming precision and continuous pile group construction efficiency in the complex gravel interlayer area.

Description

Technical Field

[0001] This invention relates to the field of foundation treatment construction technology, and in particular to a method for precise drilling construction of compaction piles to prevent collapse in complex gravel interlayer strata. Background Technology

[0002] Lime-soil compaction piles are typically constructed by creating pile holes in the foundation, filling the holes with lime-soil material in layers, and compacting each layer. This allows the lime-soil pile body and the compacted soil between the piles to jointly bear the foundation treatment load. In large-scale water conservancy projects, reservoir foundations, and dam foundation treatments, lime-soil compaction piles are typically characterized by a large number of piles, a large construction area, small pile spacing, and a wide range of pile length variations.

[0003] When the strata contain alternating layers of silty clay, gravelly soil, and gravelly lenses, the core soil is gradually expelled after the drill bit enters the gravelly interlayer. Some gravel may move into the hole, causing hole wall spalling, localized diameter enlargement, increased loose material at the bottom of the hole, and hole axis displacement. For pile group construction with small pile spacing, if adjacent piles are drilled consecutively, the unstable soil between the piles may repeatedly undergo changes in stress state, increasing the difficulty of borehole control in complex gravelly interlayer areas.

[0004] Related technologies can improve borehole stability through steel casings, solidified retaining walls, or by adding dedicated reinforcing piles around the target borehole. However, for large-area lime-soil compaction pile projects, the additional installation of dedicated permanent reinforcing piles increases the construction workload and may alter the original design of the foundation structure formed by the lime-soil piles and the soil between the piles. While existing intermittent construction methods can reduce the construction impact of continuous construction of adjacent piles, they typically arrange the construction sequence by rows, rows, or construction zones, which does not adequately utilize the local soil constraints formed by the completed original lime-soil piles. Furthermore, they lack construction openness criteria based on the actual constraint state of the target gravel interlayer. Summary of the Invention

[0005] The main purpose of this application is to provide a precise drilling method for preventing collapse of compacted soil piles in complex gravel interlayer strata. This method aims to solve the technical problems of insufficient soil constraint around the target pile before drilling in complex gravel interlayer strata, large construction volume of additional hole protection structures, and difficulty in reflecting the actual soil condition of the gravel interlayer by determining the construction time of the target pile solely based on the number of peripheral piles.

[0006] To achieve the above objectives, the present invention provides a method for precise hole drilling for preventing collapse of compaction piles in complex gravel interlayer strata, the method comprising the following steps:

[0007] S1: Obtain pile location information and stratum information of the target area, determine the target pile and the surrounding design piles based on the pile location information and stratum information, and establish a self-containment construction unit;

[0008] S2: Based on the spatial position of the peripheral design piles relative to the target piles, the peripheral design piles are divided into at least two construction batches;

[0009] S3: Construct the peripheral design piles in the order of the construction batches. After each peripheral design pile is completed, fill and compact the material immediately, and then construct another peripheral design pile in the current construction batch.

[0010] S4: Based on the distribution of the peripheral design piles around the target pile after the filling and compaction have been completed, determine whether the target pile has met the preset construction opening conditions;

[0011] S5: Position and correct the target pile that has reached the preset construction opening conditions, and carry out differentiated drilling and segmented re-measurement according to the current drilling strata until the designed hole depth is reached;

[0012] S6: For target piles that have reached the designed hole depth, perform hole bottom treatment and hole acceptance, and after acceptance, carry out layered filling and compaction;

[0013] S7: The target pile with the completed filling and compaction is used as the outer design pile of the adjacent target pile to be constructed, the self-supporting construction unit is updated and construction continues.

[0014] The proposed method for precise drilling of compaction piles in complex gravel interlayer strata to prevent collapse has at least the following technical advantages: By completing the peripheral design piles in batches before the target pile is constructed, the original design gravel piles and the soil between the compacted piles gradually form multi-directional soil constraints around the target pile; by forming a reinforced compaction section in the peripheral design piles corresponding to the depth of the gravel interlayer of the target pile, the lateral compaction degree can be improved in the elevation range where the borehole wall is most prone to collapse; by detecting the in-situ penetration parameters of the soil between the piles corresponding to the depth of the gravel interlayer, and using the effective constraint section as the open condition for the construction of the target pile, the construction time can correspond to the actual soil condition; by continuously updating the self-containment construction unit by sharing the constraint side and the side to be supplemented, the formed soil constraints can be reused in continuous high-risk areas, reducing the equipment movement required for repeated adjustments to the construction sequence, while maintaining the spatial continuity of the completed piles around the target pile. Attached Figure Description

[0015] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the accompanying drawings used in the description of the embodiments are briefly introduced below. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0017] Figure 1 This is a schematic diagram of the overall process for the precise drilling construction method of compaction piles for preventing collapse in complex gravel interlayer strata, as described in this application.

[0018] Figure 2 This is a schematic diagram of the plan structure of the target pile, the outer design piles, and the self-supporting construction unit in this application;

[0019] Figure 3 This is a schematic diagram showing the longitudinal relationship between the ordinary pile segment and the reinforced compaction segment of the outer perimeter design piles in this application;

[0020] Figure 4 This is a schematic diagram illustrating the circumferential section inspection and the determination of pre-set construction opening conditions in this application;

[0021] Figure 5 This is a schematic diagram of the planar construction sequence of the seven pile construction units in the specific construction example of this application.

[0022] The purpose, features, and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0023] It should be understood that the specific embodiments described herein are used to explain the technical solutions of this application and are not intended to limit this application. For those skilled in the art, equivalent substitutions or adaptive adjustments made based on the technical content disclosed in this application can all be used as executable implementation methods of this application.

[0024] The main construction scheme of this application is as follows: First, the target piles in the complex gravel interlayer area are identified and self-contained construction units are established; then, the peripheral design piles around the target piles are divided into at least two construction batches according to their spatial location; subsequently, the peripheral design piles are constructed one by one according to the construction batches, and a reinforced compaction section is set at the depth corresponding to the gravel interlayer of the target pile; after the peripheral design piles are completed, the soil condition between the piles at the corresponding depth of the gravel interlayer is detected between adjacent peripheral design piles; after each preset circumferential range forms an effective constraint section, the target piles are constructed; after the target piles are completed, they serve as reusable peripheral piles in the next construction unit, using existing continuously completed piles to form a shared constraint side, and new peripheral design piles are gradually completed from the remaining supplementary sides.

[0025] It should be noted that, in this application, "target pile" refers to a soil compaction pile designed based on pile location information and stratum information, which needs to be drilled after the predetermined construction conditions are formed by the peripheral design piles; "peripheral design pile" refers to a soil compaction pile located around the target pile in the original design pile location of the target area, which is filled and compacted before the target pile according to the predetermined construction sequence; "self-containment construction unit" refers to a phased construction organization unit consisting of a target pile and several peripheral design piles selected around the target pile.

[0026] In this application, after the outer design piles are compacted with lime-soil fill, the pile body and the surrounding compacted soil can jointly improve the lateral restraint in multiple directions around the target pile. All outer design piles are original lime-soil compaction piles designed for the project, and after construction, they still serve as foundation treatment according to design requirements. This application further utilizes the spatial location of the target pile's gravel interlayer, setting up reinforced compaction sections at corresponding depths of the outer design piles, and determining the openness of the target pile construction through actual soil testing results between piles. This establishes a direct correlation between the prior construction of the outer design piles and the actual drilling risk of the target gravel interlayer.

[0027] Based on this, the embodiments of this application provide a method for precise hole drilling and construction of compaction piles for preventing collapse in complex gravel interlayer strata. For example... Figure 1 As shown, the construction method in this embodiment includes steps S1 to S7.

[0028] Step S1: Obtain pile location information and stratum information of the target area; determine the target pile and the surrounding design piles based on the pile location information and stratum information; and establish a self-supporting construction unit.

[0029] In this embodiment of the invention, the target area is first prepared and the pile positions are verified before construction. Construction personnel establish a unified planar coordinate system for the target area based on the design drawings, converting the center position of each designed lime-soil compaction pile into pile position information under the unified coordinate system. This pile position information is used to express the planar position and adjacency relationship of each designed pile, in order to determine the adjacent designed piles around a given designed pile that can be constructed in advance.

[0030] Specifically, the design pile positions in the target area are mapped to a unified plane coordinate system, and the location of the gravel interlayer within the range of each design pile hole is marked according to the geological information. Based on the location of the gravel interlayer, the design piles that meet the preset risk conditions are determined as the target piles. The design piles distributed along the circumference of the target piles are selected from the adjacent design piles of the target piles as the peripheral design piles, and the target piles and the peripheral design piles constitute the self-supporting construction unit.

[0031] The geological information can come from engineering survey data, supplementary survey boreholes, test pile records, and field records of adjacent constructed piles. The geological information is used to determine the upper and lower limits of the gravel interlayer within the designed borehole depth range, as well as its extent on the plane. For example, if a designed pile has a length of 8m, and the geological verification results show a continuous gravel mixture layer from 3.4m to 4.6m underground, then 3.4m is recorded as the upper limit of this gravel interlayer, and 4.6m is recorded as the lower limit.

[0032] It is readily understood that the preset risk conditions can be determined based on the results of engineering test piles. For example, one or more of the following conditions can be used as target pile screening criteria: the presence of a gravel interlayer with a preset thickness within the designed borehole depth range, the presence of multiple gravel lenses, obvious borehole wall spalling at the corresponding depth of adjacent construction piles, or abnormal drilling conditions. In one feasible implementation, piles with any continuous gravel interlayer thickness exceeding 0.8m, or with a cumulative gravel interlayer thickness exceeding 20% ​​of the designed pile length, can be listed as priority target candidate piles.

[0033] In one feasible implementation, the planar coordinates, design pile length, upper and lower boundaries of the crushed stone interlayer, and current construction status of each design pile can be written into a digital pile location map. The construction status can be represented by three states: not under construction, under construction, and completed filling and compaction. This digital pile location map is only used to assist in construction sequencing; construction personnel can also complete the same operation using paper construction drawings with pile numbers and stratum records.

[0034] like Figure 2 As shown, when an equilateral triangle pile layout is used in the target area, there are usually six adjacent design piles in the first ring around an inner target pile P0, which can be labeled P1 to P6 in circumferential order. In this case, P0 serves as the target pile, and P1 to P6 serve as the outer design piles, forming a self-contained construction unit from the aforementioned seven original design lime-soil compaction piles. When the target pile is located at the edge of the construction area, three to five adjacent design piles in the first ring can be selected based on the actual pile location, or the original design piles in the second ring closer to the direction of weaker soil constraint can be included in the construction earlier.

[0035] Step S2: According to the spatial position of the peripheral design piles relative to the target piles, the peripheral design piles are divided into at least two construction batches.

[0036] In this embodiment of the invention, the principle of phased construction of the peripheral design piles is to ensure that the peripheral design piles in the first construction batch are spaced apart from the target piles in the circumference. After the first construction batch is completed, the pile body and the compacted soil around the pile can provide the existing construction conditions for the subsequent peripheral design piles. Subsequent construction batches are used to gradually fill the circumferential range between the piles of the first construction batch.

[0037] Specifically, the peripheral design piles are sorted according to the circumferential order around the target pile; the peripheral design piles that are not adjacent to each other in the circumferential order are assigned to the first construction batch; and the remaining peripheral design piles located between two adjacent peripheral design piles in the first construction batch are assigned to subsequent construction batches.

[0038] like Figure 2As shown, taking six peripheral design piles (P1 to P6) as an example, P1, P3, and P5 can be classified into the first construction batch, and P2, P4, and P6 into the second construction batch. After completing P1, P3, and P5, three intervals of completed lime-soil pile areas are first formed around the target pile P0; then P2, P4, and P6 are constructed, so that the subsequent peripheral design piles are located between adjacent completed piles in the first construction batch.

[0039] In practical applications, when there are 4 peripheral design piles, two adjacent peripheral design piles can be included in the first construction batch, and the remaining two in the second construction batch. When there are 5 peripheral design piles, 2 or 3 peripheral design piles that are not directly adjacent to each other in the circumferential direction can be selected first, and then the remaining peripheral design piles can be constructed. When the pile positions are locally irregular, the peripheral design piles can be sorted according to their azimuth angles relative to the center of the target pile, and the interval positions from the sorting results can be selected as the first construction batch.

[0040] The peripheral design piles are all original lime-soil compaction piles designed for the target area. The first construction batch and subsequent construction batches only change the construction sequence of the original design piles, without changing the design pile positions, the final number of piles, or the function of the final lime-soil piles.

[0041] Step S3: Construct the peripheral design piles in sequence according to the construction batches. After each peripheral design pile is completed, fill and compact the material immediately before constructing another peripheral design pile in the current construction batch.

[0042] In this embodiment of the invention, the peripheral design piles are constructed one by one as a complete unit. Only after the drilling rig is positioned, the hole is drilled, inspected, and the lime-soil fill is compacted for the current peripheral design pile can the next peripheral design pile in the current construction batch begin. Simultaneously, based on the depth of the gravel interlayer in the target pile, a reinforced compaction section is set within the peripheral design piles, concentrating the strengthening and compaction effect of the peripheral design piles on the elevation range where the target pile most needs improved borehole stability.

[0043] Specifically, the drilling rig is positioned at the current peripheral design pile and its position is corrected. The hole is drilled to the design depth according to the location of the crushed stone interlayer. Based on the upper and lower boundaries of the crushed stone interlayer of the target pile, a reinforced compaction section corresponding to the crushed stone interlayer is determined in the current peripheral design pile. The single-layer filler thickness of the reinforced compaction section is smaller than that of the ordinary pile section, and the single-layer cumulative compaction energy of the reinforced compaction section is increased. After the current peripheral design pile has completed the filler compaction to the design elevation, another peripheral design pile in the current construction batch is constructed.

[0044] When locating the outer perimeter design piles, a total station can be used to verify the pile center, and the drill rod should be corrected after the drilling rig base is leveled. When entering the general silty clay layer, the normal drilling speed corresponding to that layer should be used, and the axial advance should be gradually reduced before entering the gravel mixed layer. After the outer perimeter design piles reach the design depth, the loose material at the bottom of the hole should be treated, and the hole depth, diameter, and verticality should be checked.

[0045] The reinforced compaction section corresponds to the target pile's gravel interlayer in elevation. Let the upper boundary depth of the target pile's gravel interlayer be z1 and the lower boundary depth be z2. The reinforced compaction section can be defined as the area extending a predetermined compensation distance Δz1 above z1 to a predetermined compensation distance Δz2 below z2 within the outer design piles. The upper boundary depth of the reinforced compaction section can be expressed as z1 - Δz1, and the lower boundary depth as z2 + Δz2. Here, z1 and z2 represent the upper and lower boundary depths of the target pile's gravel interlayer, respectively; Δz1 and Δz2 represent the upper and lower compensation distances used to cover changes in the geological interface, respectively.

[0046] like Figure 3 As shown, in one feasible implementation, when the target pile's gravel interlayer is located at 3.4m to 4.6m, Δz1 and Δz2 can both be taken as 0.2m, and the pile segment corresponding to the outer design pile at 3.2m to 4.8m can be determined as the reinforced compaction section. For areas with significant undulations in the underground gravel interlayer interface, the compensation distance can be increased to 0.3m to 0.5m. The compensation distance is mainly used to cover the possible difference in ground interface elevation between the survey location and the actual pile location.

[0047] Ordinary pile sections are constructed according to the single-layer fill thickness and compaction parameters determined by the engineering test piles. In the reinforced compaction section, the thickness of the lime-soil filling per pass is reduced, allowing for more fill layers to correspond to the same pile height, and increasing the cumulative compaction energy per layer. The cumulative compaction energy per layer can be achieved by maintaining the hammer mass and drop height while increasing the number of blows per layer, or by adjusting the compaction parameters within the equipment's allowable range.

[0048] Specifically, the single-layer loose-lay thickness of a standard pile section can be 300mm, while the single-layer loose-lay thickness of a reinforced compaction section can be adjusted to 180mm–240mm. Each layer of a standard pile section can be compacted 6 times, while each layer of a reinforced compaction section can be compacted 8–9 times. If the hammer mass and drop height remain constant, the cumulative compaction energy per layer of the reinforced compaction section will increase accordingly. The above parameters are only one example; specific projects can be adjusted based on the soil moisture content, pile diameter, and test pile results.

[0049] The reinforced compaction section is located inside the outer design piles. Its purpose is to ensure more thorough compaction of the outer lime-soil piles and the soil between the piles near the same elevation as the target gravel interlayer. The ordinary pile sections continue to use normal filling and compaction parameters, thus controlling additional construction time. This allows the reinforced construction to be concentrated on the location corresponding to the high-risk gravel layer of the target piles.

[0050] After the outer perimeter design piles are filled and compacted layer by layer from the bottom of the hole to the design elevation, their construction status is recorded as "filling and compaction completed." In the first construction batch, P1 is completed before P3 is constructed, followed by P5. The second construction batch, consisting of P2, P4, and P6, is then constructed only after P1, P3, and P5 are all completed. Each outer perimeter design pile uses the same construction control logic for ordinary pile sections, reinforced compaction sections, and ordinary pile sections.

[0051] It should be noted that when there are two or more separate gravel interlayers within the target pile hole area, two or more reinforced compaction sections can be set in the same outer perimeter design pile. Each reinforced compaction section corresponds to one target gravel interlayer, and the construction parameters of ordinary pile sections are still used between two reinforced compaction sections. This avoids the increase in construction time caused by uniformly increasing the compaction parameters for the entire outer perimeter pile length.

[0052] Step S4: Based on the distribution status of the peripheral design piles with the completed filling and compaction around the target pile, determine whether the target pile has met the preset construction opening conditions.

[0053] In this embodiment of the invention, the number of completed peripheral design piles reflects the construction progress of the self-supporting construction unit, and the actual state of the soil between the piles is used to further confirm whether the soil between the peripheral design piles forms a constraint that meets the construction requirements. For the target pile to reach the preset construction opening conditions, both the spatial location of the completed piles and the state of the soil between the piles at the corresponding depth of the crushed stone interlayer must be considered.

[0054] Specifically, detection positions are set between adjacent completed peripheral design piles, and in-situ penetration parameters of the soil between piles are obtained within the depth range corresponding to the crushed stone interlayer of the target pile. When all adjacent peripheral design piles constituting a circumferential section have completed filling and compaction, and the in-situ penetration parameters corresponding to the circumferential section reach a preset threshold, the circumferential section is determined as an effective constraint section. When the effective constraint sections are formed within the preset circumferential range of the target pile, the target pile is determined to have met the preset construction opening conditions. When there is a circumferential section that has not formed an effective constraint section, the original design piles that have not yet been completed in the direction corresponding to the circumferential section are constructed first, and the in-situ penetration parameters are obtained again.

[0055] like Figure 4As shown, taking six outer design piles as an example, the intervals between P1 and P2, P2 and P3, P3 and P4, P4 and P5, P5 and P6, and P6 and P1 can each be defined as a circumferential section. At least one detection point can be set near the center line connecting two adjacent outer design piles in each circumferential section. A preset safety distance is maintained between the detection points and the outer design piles to prevent the detection holes from entering the already formed lime-soil pile body.

[0056] The in-situ penetration parameters can be obtained through dynamic penetration testing, static penetration testing, or other in-situ penetration testing methods permitted by construction specifications, applicable to the engineering strata. For gravelly mixed soils, dynamic penetration testing methods adapted to gravelly soils are preferred. It should be noted that this application does not impose a unique limitation on the specific testing equipment model, as long as it can obtain in-situ parameters reflecting the degree of compaction of the soil between piles or changes in penetration resistance at the corresponding depth.

[0057] The testing depth corresponds to the crushed stone interlayer of the target pile. For example, if the crushed stone interlayer of the target pile is located at 3.4m to 4.6m, the in-situ penetration parameters within the 3.4m to 4.6m range can be focused on, or continuous testing can be conducted within the 3.2m to 4.8m range to ensure the testing range corresponds to the coverage area of ​​the reinforced compaction section of the outer piles. This allows verification of whether the soil between adjacent outer piles has reached the expected construction state after the reinforced compaction section is constructed.

[0058] The preset threshold can be determined through the test pile area before formal construction. Specifically, a test pile group that has been proven to be able to stably form the target hole can be selected in an area with similar geological conditions. In-situ penetration tests are conducted on the soil between the piles, and representative parameters corresponding to the depth range of the gravel layer are used as reference values ​​for open construction. In actual construction, when the in-situ penetration parameters obtained at the test location are not lower than the reference value or reach the allowable range determined by the project, the soil at that test location can be considered to have reached the predetermined state.

[0059] In one feasible implementation, when multiple detection positions are set for a circumferential section, all detection positions can be required to reach a preset threshold, or a preset proportion of detection positions can be required to reach the threshold according to engineering test results. To make on-site control more direct, it is preferable to set a representative detection position for each circumferential section and require the in-situ penetration parameters within the target gravel interlayer depth range corresponding to that position to reach a preset threshold.

[0060] When both P1 and P2 have been compacted, and the in-situ penetration parameters of the crushed stone layer depth corresponding to the detection positions between P1 and P2 reach the preset threshold, the circumferential section corresponding to P1-P2 is marked as an effective constraint section. The circumferential sections corresponding to P2-P3, P3-P4, P4-P5, P5-P6, and P6-P1 are evaluated in the same manner.

[0061] The preset circumferential range is determined based on the location of the target pile. For target piles located within the construction area, all planned circumferential sections surrounding the target pile are required to form effective constraint sections. For target piles located at the boundary of the construction area, their effective circumferential range can be determined based on the actual existing design piles, while prioritizing sections closer to the construction boundary and with weaker original lateral constraints to meet the preset requirements.

[0062] If the in-situ penetration parameters of a certain circumferential section do not reach the preset threshold, that section is temporarily not considered a valid constraint section, and the target pile construction remains suspended. Construction personnel check the status of the original design piles in the corresponding direction of that section and prioritize the construction of adjacent, unfinished, original design lime-soil compaction piles. Newly designed piles are constructed following the same steps as in step S3: hole drilling, reinforced compaction section construction, and fill material compaction.

[0063] After the newly added design piles are completed, in-situ penetration tests are conducted again at the original test location or a nearby retest location. Once the test results reach a preset threshold, the circumferential section is updated as an effective constraint section. Through the above process, the construction opening time of the target pile is determined jointly by the completion status of the outer design piles and the actual soil condition between the piles.

[0064] For example, after P1 to P6 are all completed, P1-P2, P2-P3, P3-P4, P4-P5, and P6-P1 all reach the preset thresholds, while the corresponding section P5-P6 does not meet the requirements. In this case, construction on P0 is temporarily suspended. At this point, priority can be given to constructing the next adjacent lime-soil compaction pile located outside P5-P6 and within the original design range to further compact the soil in the P5-P6 direction. Then, the section is re-measured. P0 is opened after the re-measurement shows the threshold has been reached.

[0065] This open approach allows for a continuous construction assessment process, integrating the completed peripheral design piles with the established soil conditions around the target crushed stone layer. For areas with significant lateral variations in the crushed stone interlayer distribution, this reduces the inadequacy of on-site adaptability that can result from simply arranging target piles according to a fixed number of piles.

[0066] Step S5: Position and correct the target pile that meets the preset construction opening conditions, and carry out differentiated drilling and segmented re-measurement according to the current drilling strata until the designed hole depth is reached.

[0067] In this embodiment of the invention, the drilling rig is moved to the target pile location only after the target pile has reached the conditions for construction. At this time, the planned circumferential range around the target pile has formed an effective constraint section. The target pile still needs to be positioned and drilled according to its own geological conditions.

[0068] Specifically, the drilling rig base and drill rod are orthogonally aligned to determine the borehole axis of the target pile. Drilling is then carried out along the borehole axis. When the geological information indicates that the current drilling stratum is approaching or entering a gravel interlayer, the axial advance is reduced and a low-speed, short-cut drilling method is adopted. The axial advance is stopped and the drill rod posture is re-measured every time a preset re-measurement depth is reached. When the drill rod posture deviation reaches a preset threshold, the drill bit is raised to the previous qualified depth and the hole is re-scanned. Then, drilling continues to the designed hole depth.

[0069] During drilling rig positioning, the target pile center is restored using pile position control points, aligning the drill bit center with the pile center. The drilling rig base is then adjusted, and the drill rod posture is checked in two mutually orthogonal directions. Initial calibration can be performed using a laser inclinometer in conjunction with a two-way horizontal detection tool, while the drill frame guide structure is used to limit lateral swaying of the long drill rod during construction.

[0070] In one implementation, after the drilling rig completes initial leveling, the drill bit can be lightly touched to the ground and a force close to the normal initial drilling state can be applied. After the drilling rig base stabilizes, the horizontal state and the vertical state of the drill rod are checked again. When the ground surface is locally soft, this operation can reduce the impact of the base position change on the borehole shaft after the drilling rig switches from no-load to working state.

[0071] When the current drilling formation is silty clay, a first drilling speed is used; when the formation information indicates that the current drilling formation is a gravel interlayer, a second drilling speed lower than the first drilling speed is used, and the axial advance is reduced. In one executable implementation, the first drilling speed can be 0.8 m / min to 1.0 m / min, and the second drilling speed can be 0.4 m / min to 0.6 m / min.

[0072] When the drill bit is 0.3m to 0.5m away from the upper boundary of the gravel interlayer, the drilling speed and axial advance can be gradually reduced. After the drill bit enters the gravel interlayer, a low-speed, short-penetration method should be adopted. For example, axial advance can be stopped every 0.2m to 0.4m, and the drill string can be kept rotating at a low speed for several seconds before continuing to drill the next short distance. For interlayers with larger rock particle sizes or significant local resistance changes, the single short-penetration distance can be reduced accordingly.

[0073] When the drill string encounters resistance at the preset resistance level, the axial advance should be stopped, the drill string should be slightly lifted, and the hole should be re-sweeped. The preset resistance level can be determined based on the drilling rig's workload and actual drilling progress. For example, if the workload continues to increase while the drilling progress per unit time decreases significantly, the downward advance can be stopped, the drill string can be lifted by 0.1m to 0.3m, and the drill string can be rotated at a low speed to pass through the current hole section again.

[0074] Segmented re-measurement can be performed at a fixed drilling depth. For example, after drilling 1 meter, axial advance is stopped and the attitude of the drill rod in two orthogonal directions is re-measured. Drilling continues as long as the attitude deviation remains within a preset threshold; when the attitude deviation reaches the preset threshold, the current abnormal depth is recorded, the drill bit is raised to near the previous acceptable depth, and the drill rod is recalibrated before being swept through the hole segment at low speed. It should be noted that the previous acceptable depth refers to the depth at which the drill rod attitude met the construction requirements in the previous segmented re-measurement. By using the existing acceptable upper hole segment to guide the drill bit through the abnormal hole segment, the downward development of hole axis deviation caused by unilateral force from localized rock blocks can be reduced.

[0075] Step S6 involves treating the bottom of the target pile that has reached the designed hole depth and conducting hole acceptance. After the acceptance is passed, layered filling and compaction are carried out.

[0076] In this embodiment of the invention, after the target pile reaches the designed hole depth, the loose material at the bottom of the hole is first removed, and then the hole depth, diameter, and verticality are checked. After passing the inspection, the lime-soil filling and compaction process is carried out as soon as possible to reduce the time the pile hole remains empty.

[0077] Specifically, the axial advance is stopped and the drill bit is rotated in place before being pulled up at low speed to remove loose material from the bottom of the hole; the hole depth, diameter and verticality of the target pile are checked, and the hole is deemed to be qualified when the test results meet the preset hole formation standards; from the time the hole is deemed qualified, lime-soil is filled into the target pile in layers within a preset time and compacted layer by layer to the design elevation.

[0078] In one implementation, when the drill bit approaches the last 0.3m to 0.5m of the designed hole bottom, the axial advance is reduced; after reaching the designed depth, axial advance is stopped, and the drill bit is rotated in place for 20s to 40s to bring fine particles and loose debris from the hole bottom into the auger blades, and then the drill bit is lifted at a low speed. If a small amount of debris is found to have fallen back into the hole bottom, a short rescan of the hole bottom can be performed.

[0079] Hole depth can be cross-checked using mechanical depth marking and electronic depth recording; hole diameter can be detected using a detector matching the designed hole diameter; verticality can be determined by combining drill rod records during construction and final hole inspection results. In one embodiment, the hole depth error can be controlled within ±30mm, and the hole verticality can be controlled within 1%, with the actual control values ​​determined based on engineering design and applicable construction specifications.

[0080] Once the borehole has passed inspection, it is preferable to begin filling with lime-soil within 30 minutes. The first layer of lime-soil should be compacted to the bottom of the hole before proceeding with the next layer. As the height of the lime-soil filling increases, the empty height of the pile hole gradually decreases. Once the target pile has reached the design elevation, its construction status is recorded as "filling and compaction completed."

[0081] Step S7: The target pile with the completed filling and compaction is used as the outer design pile of the adjacent target pile to be constructed, the self-supporting construction unit is updated and construction continues.

[0082] In this embodiment of the invention, after the current target pile is completed, it is used as a peripheral design pile that can be reused by adjacent unconstructed target piles. When updating the construction unit, the completed piles continuously distributed in the previous construction unit are used first to form a shared constraint side, and the direction for the remaining directions of the next target pile that have not yet formed peripheral conditions is determined to be the side to be supplemented.

[0083] Specifically, the target pile that has been filled and compacted is updated to a reusable outer pile, and the next target pile is determined from the target piles to be constructed adjacent to the reusable outer pile; the circumferential range corresponding to the continuous completed design piles around the next target pile and the previous self-containment construction unit is determined as the shared constraint side, and the circumferential range corresponding to the remaining outer design piles to be constructed is determined as the supplementary side; the missing outer design piles are constructed sequentially from both ends of the supplementary side towards the middle, and the next target pile is constructed after the next target pile reaches the preset construction opening condition.

[0084] Assume that the central target pile of the first self-contained construction unit is P0. After P0 is completed, the adjacent target pile Q0 to be constructed shares P0 with the previous construction unit, as well as two other continuous completed original design piles. The continuous completed design piles form a circumferential range on one side of Q0 that is ready for construction, and this range is defined as the shared constraint side.

[0085] The remaining unfinished peripheral design piles around Q0 are defined as the circumferential area of ​​the side to be supplemented. During construction, it is not necessary to reconstruct the design piles on the shared constraint side; instead, starting from the two ends of the side to be supplemented, the missing peripheral design piles are constructed sequentially towards the center of the side to be supplemented. Each newly added peripheral design pile still follows step S3 to set up a reinforced compaction section corresponding to the Q0 crushed stone interlayer.

[0086] After the newly added peripheral design piles on the supplementary side are completed, in-situ penetration testing of the soil between adjacent completed piles will be conducted according to step S4. If the existing test records on the shared constraint side are still within the effective time range allowed by construction control and no other construction has occurred on site that has changed the soil condition, the existing test results can be used directly; if the site conditions change significantly, the shared constraint side can be retested.

[0087] Construction proceeds from both ends of the side to be supplemented towards the center, allowing the newly completed piles to gradually connect with the shared constraint side. For example, if the side to be supplemented includes three unfinished peripheral design piles Q1, Q2, and Q3, Q1, which is closer to one end of the shared constraint side, and Q3, which is at the other end, can be constructed first, followed by Q2, which is located in the middle. After completing the aforementioned peripheral design piles and forming an effective constraint section within the preset circumferential range, the central target pile Q0 can then be opened.

[0088] After Q0 is completed, its status is updated again to reusable peripheral piles. When selecting the next adjacent target pile R0, a new shared constraint side can be formed using Q0 and its continuously adjacent completed design piles, and then construction can be carried out on the side of R0 to be supplemented. This allows for the formation of a progressively advancing construction face in a high-risk area of ​​continuous crushed stone.

[0089] Under digital construction management, the spatial location of completed design piles around the target pile to be constructed can be read, and consecutive adjacent completed pile groups can be identified. If a candidate target pile has a longer shared constraint side, it can be given priority as the next target pile candidate. It should be noted that digital sorting is only used to assist in construction planning; the core construction process of this application can also be completed directly by construction personnel based on the pile location map.

[0090] The following is a complete and specific construction example to further illustrate the actual implementation process of steps S1 to S7, as well as the reinforced compaction section, the effective constraint section, and the shared constraint side. The parameters described below are intended to enable those skilled in the art to understand and implement this application, and do not limit all projects to using the same values.

[0091] In a certain lime-soil compaction pile construction area, an equilateral triangle pile layout was adopted, with a designed pile spacing of 1.4m and a designed pile length of 8m in the target area. The strata, from top to bottom, include an upper silty clay layer, a gravel-mixed interlayer, and a lower silty clay layer. According to the pre-construction review, a continuous gravel-mixed interlayer exists at a depth of 3.4m to 4.6m. Previous test drilling in this elevation range showed local increases in borehole diameter and significant changes in drilling resistance. Therefore, this area was identified as the target area for using the method of this application.

[0092] like Figure 5 As shown, design pile A37 is selected as target pile P0, and the six adjacent design piles in the first ring around it, A31, A32, A36, A38, A42, and A43, correspond to P1 to P6 respectively. P1, P3, and P5 are assigned to the first construction batch, and P2, P4, and P6 are assigned to the second construction batch. The first construction batch is constructed one pile at a time in the order of P1, P3, and P5, and the next pile is constructed only after the lime-soil filling is completely compacted after each pile is completed.

[0093] The upper boundary of the crushed stone interlayer in P0 is 3.4m, and the lower boundary is 4.6m. When constructing the outer perimeter design piles, the 3.2m to 4.8m section is designated as the reinforced compaction section, with an additional 0.2m compensation range above and below the crushed stone interlayer. For the ordinary pile section of the outer perimeter design piles, a single layer of loose paving thickness of approximately 300mm is used, with each layer compacted 6 times. After entering the 3.2m to 4.8m reinforced compaction section, the single layer of loose paving thickness is adjusted to approximately 200mm, with each layer compacted 8 times. After leaving the reinforced compaction section, the parameters for the ordinary pile section are restored.

[0094] After the first construction phase was completed, P2, P4, and P6 were constructed, and all six peripheral design piles were completed to the design elevation. Due to the high unit height compaction work used for each peripheral design pile in the depth range of 3.2m to 4.8m, the soil around the piles near this depth was subjected to more sufficient lateral compaction, forming a reinforced constraint zone corresponding to the P0 gravel interlayer elevation.

[0095] Detection positions D12, D23, D34, D45, D56, and D61 are set between P1—P2, P2—P3, P3—P4, P4—P5, P5—P6, and P6—P1, respectively. In-situ penetration parameters within a depth range of 3.4m to 4.6m are detected using an engineering-permissible dynamic cone penetration test method. The preset threshold is determined based on the soil testing results between piles in the adjacent test pile area, where the target hole can be stably completed.

[0096] The initial test results showed that D12, D23, D34, D45, and D61 all reached the preset threshold, while D56 was below the preset threshold. Therefore, P1-P2, P2-P3, P3-P4, P4-P5, and P6-P1 were identified as effective constraint sections, while P5-P6 did not yet form an effective constraint section, and P0 remained in a state of suspended construction.

[0097] Upon review of the construction drawings, it was discovered that a soil-cement compaction pile A48, which was not yet constructed and fell within the original engineering design scope, existed outside P5-P6. Construction of A48 was completed first, with reinforced compaction parameters applied to the corresponding 3.2m-4.8m pile segment. After A48 was completed, in-situ penetration testing was conducted again near D56. The test results met the preset threshold, thus updating the corresponding section of P5-P6 as an effective constraint section. At this point, the planned circumferential area around P0 met the construction conditions, confirming that P0 met the preset construction opening conditions.

[0098] After the drilling rig is positioned at P0, the base is leveled and the drill rod is aligned in both directions. The drilling speed is controlled at approximately 0.9 m / min within the 0 m to 3.0 m silty clay range; as approaching the 3.4 m gravel interlayer, the axial advance is gradually reduced; after entering the gravel interlayer, the drilling speed is adjusted to approximately 0.5 m / min, and short advances of approximately 0.3 m are adopted. After each short advance, axial advance is temporarily stopped, and the drill bit is rotated at low speed before continuing drilling.

[0099] Drill rod attitude was re-measured at drilling depths of 1m, 2m, 3m, 4m, 5m, 6m, and 7m. At approximately 4m, an increased attitude deviation was detected in one direction. The drill bit was raised to near the previous acceptable depth and slowly re-swept through that section before drilling continued. After the correction, subsequent re-measurements for each section returned to within the acceptable range for construction.

[0100] After reaching the designed hole depth of 8m at P0, axial advance is stopped, the hole is rotated in place for about 30 seconds, and then the drill is lifted at low speed. After completing the hole depth, diameter, and verticality checks, lime-soil filling begins within 30 minutes, and the soil is compacted layer by layer to the design elevation. After P0 is completed, its status is updated to reusable outer pile on the construction drawings.

[0101] Select the next target pile to be constructed, Q0, adjacent to P0. There are a total of 6 planned peripheral design piles around Q0. Among them, P0 and two other design piles from the previous self-supporting construction unit have been completed consecutively. The circumferential range corresponding to the above 3 design piles forms the shared constraint side of Q0. There are still 3 peripheral design piles on the other side of Q0 that have not been completed. The range corresponding to these 3 piles forms the side to be supplemented.

[0102] When constructing the supplementary side, first construct the outer design piles near the first end of the shared constraint side, then construct the outer design piles near the other end of the shared constraint side, and finally construct the outer design piles in the middle of the side to be supplemented. All the newly added outer design piles have reinforced compaction sections based on the crushed stone interlayer corresponding to Q0. After the new piles are completed, in-situ penetration testing is performed on the newly formed circumferential section.

[0103] Once the pre-defined circumferential range of Q0 has formed an effective constrained section, the drilling and compaction of the lime-soil filling for Q0 are completed according to steps S5 and S6. Q0 is then used as a reusable outer pile for the third construction unit. In this manner, the construction unit can be progressively updated along the continuous crushed stone interlayer area.

[0104] Furthermore, when a target pile has two crushed stone interlayers, such as 3.0m–3.7m and 5.2m–6.0m, corresponding first and second reinforced compaction sections can be set on the outer design piles, respectively. In-situ penetration tests are also conducted at the corresponding depths of the two crushed stone interlayers. Only after the circumferential sections corresponding to both depth ranges meet the preset engineering requirements are the target piles determined to be ready for construction.

[0105] For the boundary location of the target area, if there are no complete first-ring outer design piles on one side, the original design piles within the boundary that can form constraints can be used as shared or supplementary construction objects, and priority should be given to detecting the pile positions corresponding to the direction with weaker soil constraints. If necessary, the original design lime-soil compaction piles in the second ring can be constructed in advance to supplement the effective constraint section in that direction.

[0106] For cases where large pieces of gravel cause anomalies in single-point data during in-situ penetration testing, retest locations can be set at preset distances around the original test site. If the retest results are at the same level as multiple neighboring test results, the retest results can be used as the basis for judging that circumferential section. The specific retest distance and number of tests can be determined according to the engineering testing procedures.

[0107] In one construction quality recording method, each target pile corresponds to a construction record sheet. The construction record sheet must at least record the target pile number, the depth of the crushed stone interlayer, the outer design pile number, the range of the reinforced compaction section for each outer design pile, the detection location of each circumferential section, the in-situ penetration parameters, the status of the effective constraint section, the target pile drilling time, the results of segmented re-measurement, and the drilling acceptance results. These construction records facilitate subsequent adjacent construction units in determining whether the shared constraint side can be directly used.

[0108] When the shared constraint side has been formed for a long time, or when the area has undergone construction activities that may change the soil condition between piles, such as heavy vehicle traffic, rain soaking, or excavation, the representative detection location of the shared constraint side can be re-detected. If the re-detection meets the preset threshold, it can continue to be used as the shared constraint side for the next construction unit; if it does not meet the threshold, the required construction conditions can be re-established by constructing the original design piles in the corresponding direction that have not yet been completed.

[0109] The above description is only a part of the embodiments of this application and does not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct or indirect applications in other related technical fields, are included in the patent protection scope of this application.

Claims

1. A method for precise hole drilling in the construction of compacted soil piles for collapse prevention in complex gravel interlayer strata, characterized in that, The method includes the following steps: S1: Obtain pile location information and stratum information of the target area, determine the target pile and the surrounding design piles based on the pile location information and stratum information, and establish a self-containment construction unit; S2: Based on the spatial position of the peripheral design piles relative to the target piles, the peripheral design piles are divided into at least two construction batches; S3: Construct the peripheral design piles in the order of the construction batches. After each peripheral design pile is completed, fill and compact the material immediately, and then construct another peripheral design pile in the current construction batch. S4: Based on the distribution of the peripheral design piles around the target pile after the filling and compaction have been completed, determine whether the target pile has met the preset construction opening conditions; S5: Position and correct the target pile that has reached the preset construction opening conditions, and carry out differentiated drilling and segmented re-measurement according to the current drilling strata until the designed hole depth is reached; S6: For target piles that have reached the designed hole depth, perform hole bottom treatment and hole acceptance, and after acceptance, carry out layered filling and compaction; S7: The target pile with the completed filling and compaction is used as the outer design pile of the adjacent target pile to be constructed, the self-supporting construction unit is updated and construction continues.

2. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 1, characterized in that, Step S1: Obtain pile location information and stratum information of the target area; based on the pile location information and stratum information, determine the target pile and the surrounding design piles; and establish a self-supporting construction unit, including: S11: Obtain pile location information and stratum information of the target area, map the designed pile locations of the target area to a unified plane coordinate, and mark the location of the gravel interlayer within the range of each designed pile hole according to the stratum information; S12: Based on the location of the crushed stone interlayer, the design pile that meets the preset risk conditions is determined as the target pile; S13: Select design piles distributed along the circumference of the target pile from the adjacent design piles of the target pile as peripheral design piles, and form a self-protection construction unit by the target pile and the peripheral design piles.

3. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 2, characterized in that, Step S2: Based on the spatial position of the peripheral design piles relative to the target piles, divide the peripheral design piles into at least two construction batches, including: S21: Sort the peripheral design piles according to the circumferential order of the peripheral design piles around the target pile, and classify the peripheral design piles that are not adjacent to each other in the circumferential order into the first construction batch. S22: The remaining peripheral design piles located between two adjacent peripheral design piles in the first construction batch will be included in subsequent construction batches.

4. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 3, characterized in that, The peripheral design piles are all the original design lime-soil compaction piles of the target area. The peripheral design piles in the first construction batch are set at intervals along the circumference of the target piles, and the peripheral design piles in the subsequent construction batches are located between the adjacent peripheral design piles of the first construction batch.

5. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 1, characterized in that, Step S3: Construct the peripheral design piles sequentially according to the construction batches, including: S31: Position the drilling rig to the current outer design pile and complete the position correction, and drill the hole to the design depth according to the location of the crushed stone interlayer; S32: Based on the upper and lower boundaries of the crushed stone interlayer of the target pile, determine the reinforced compaction section corresponding to the crushed stone interlayer in the current peripheral design piles; S33: The thickness of a single layer of fill material in the reinforced compaction section is smaller than that in the ordinary pile section, and the cumulative impact energy of a single layer in the reinforced compaction section is increased in accordance with the first preset method; S34: After the current peripheral design piles have been filled and compacted to the design elevation, the other peripheral design pile in the current construction batch will be constructed.

6. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 1, characterized in that, Step S4: Based on the distribution of the peripheral design piles around the target pile after the filling and compaction have been completed, determine whether the target pile has met the preset construction opening conditions, including: S41: Set up detection positions between adjacent completed peripheral design piles, and obtain in-situ penetration parameters of the soil between piles within the depth range corresponding to the gravel interlayer of the target pile; S42: When all adjacent peripheral design piles constituting the circumferential section have been filled and compacted, and the in-situ penetration parameters corresponding to the circumferential section reach a preset threshold, the circumferential section is determined as an effective constraint section. S43: When the effective constraint section is formed within the preset circumferential range of the target pile, determine whether the target pile has met the preset construction opening conditions; S44: When there is a circumferential section that has not formed the effective constraint section, first construct the original design piles that have not yet been completed in the corresponding direction of the circumferential section, and then re-obtain the in-situ penetration parameters.

7. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 6, characterized in that, Step S5: Position and correct the target pile that meets the preset construction opening conditions, and implement differentiated drilling and segmented re-measurement according to the current drilling strata until the designed hole depth is reached, including: S51: Correct the drilling rig base and drill rod in mutually orthogonal directions to determine the borehole axis of the target pile; S52: Drill along the hole axis. When the formation information indicates that the current drilling formation is close to or enters a gravel interlayer, reduce the axial advance amount according to the second preset method and use a low-speed, short-foot drilling method. S53: Stop axial advance and re-measure drill rod posture when the preset retest depth is reached. When the drill rod posture deviation reaches the preset threshold, raise the drill bit to the previous qualified depth and re-sweep the hole, and then continue drilling to the designed hole depth.

8. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 7, characterized in that, The differentiated drilling is configured as follows: when the current drilling stratum is silty clay, a first drilling speed is used; when the stratum information indicates that the current drilling stratum is gravel interlayer, a second drilling speed lower than the first drilling speed is used, and the axial advance is reduced according to a second preset method.

9. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 1, characterized in that, Step S6: For target piles that have reached the designed hole depth, perform bottom treatment and hole acceptance, and after acceptance, carry out layered filling and compaction, including: S61: Stop axial advance for the target pile that has reached the designed hole depth, rotate the drill bit in place, and then lift the drill bit at low speed to remove loose material from the bottom of the hole. S62: Detect the hole depth, hole diameter and verticality of the target pile. When the detection results meet the preset hole formation standards, the hole formation is deemed to be qualified. S63: From the time the hole is accepted, fill the target pile with lime-soil in layers within a preset time and compact each layer to the design elevation.

10. The method for precise hole drilling for preventing collapse of compacted soil piles in complex gravel interlayer strata as described in claim 1, characterized in that, Step S7: Using the target pile with the completed filling and compaction as the outer design pile of the adjacent target pile to be constructed, updating the self-supporting construction unit and continuing construction includes: S71: The target pile that has been filled and compacted is updated as a reusable outer pile, and the next target pile is determined from the target piles to be constructed adjacent to the reusable outer pile; S72: The circumferential range of the continuous completed design piles around the next target pile and the previous self-containment construction unit is defined as the shared constraint side, and the circumferential range of the remaining outer design piles to be constructed is defined as the supplementary side. S73: Construct the missing peripheral design piles sequentially from both ends of the side to be supplemented toward the middle, and construct the next target pile after the next target pile reaches the preset construction opening conditions.

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