Foundation treatment and ore storage management method and structure for soft soil foundation stock ground

Abstract

The invention provides a foundation treatment and ore storage management method and structure for a soft soil foundation stock yard, and the method comprises the following steps: (1) before stacking, starting preparation work; (2) determining the total design stacking height H according to the total capacity of the mineral aggregates in the stock ground, and then setting multi-stage stacking H '; (3) stacking ores according to grades and recording related parameters, and (4) when the effective placement time of the ore heap reaches the grading regulation of the compacted foundation ore heap of the stockyard and the ore heap of the grade has no requirement on the consolidation degree, transferring to the next grade of ore heap; when the consolidation degree of the foundation is required, ore unloading is conducted in time, and when the shear stability safety coefficient F of the next-stage working condition is calculated to be larger than or equal to 1.10, ore stacking of the next stage can be conducted till the stacking height of the next stage is the final stage, and ore materials are safely stacked. According to the method, a drainage system of foundation soil is formed by the blind ditches and the sand cushion layers, graded stockpiling is used as a pressurization system, and the ore storage management operation process is combined, so that stockyard management is in an overall controlled state, and extremely high suitability and economical efficiency are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coastal soft soil foundation treatment and reinforcement, in particular to a soft soil foundation yard foundation treatment and ore storage management method and structure. BACKGROUND

[0002] Most of the main steel and iron metallurgical enterprises in China are located in coastal areas with soft soil foundations. The water content of soft soil foundation is high, and the compressibility is high, which leads to low foundation bearing capacity and large uneven settlement. Therefore, the foundation should be treated before it can be used as an industrial plant.

[0003] Common soft soil foundation treatment methods include drainage consolidation method (stacking preloading, vacuum preloading, etc.), gravel pile, cement mixing pile, cement fly ash gravel pile, and pile-net composite foundation method. The above methods have their own advantages and disadvantages. The existing application number 202010685847.3 invention patent "Soft soil foundation vacuum preloading combined with dynamic consolidation drainage foundation treatment method and treatment system" can treat deep soft soil layer and effectively improve the bearing capacity of shallow soil layer by laying vertical drainage system, horizontal drainage system and sealing system, vacuum preloading, accelerating soft soil layer consolidation. The disadvantage is that the strength of the foundation after treatment is still low, the mud easily blocks the plastic drainage board, and the drainage effect is weak; the existing application number 201911307890.X invention patent "Gravel pile for soft soil foundation" adds a liquid guide pipe in the gravel pile, which together with the internal and external structures of the gravel pile can guide the water in the soft soil foundation to the bottom soil layer, accelerate the water flow in the soft soil foundation, and accelerate the soft soil foundation solidification. The disadvantage is that the engineering cost is relatively high, and the post-construction settlement is not easy to control, which needs to be treated by other methods. SUMMARY

[0004] In view of the above shortcomings of the prior art, the present application provides a soft soil foundation yard foundation treatment and ore storage management method and structure. The method can be used for soft soil foundation treatment and ore storage management in coastal areas. The blind ditch and sand cushion form a drainage system for foundation soil, and the graded stacking is used as a pressurization system. The foundation bearing capacity is gradually improved through foundation soil drainage consolidation, and finally meets the load requirement, which has high adaptability and economy.

[0005] The technical scheme provided by the present application is a soft soil foundation yard foundation treatment and ore storage management method, which comprises the following steps:

[0006] (1) Before stacking, complete the embedding work of the testing instrument and the measurement and detection work before testing, obtain the initial value data of horizontal displacement, settlement displacement and deep displacement, and perform the first round of soil quality investigation to obtain relevant geotechnical mechanics parameters;

[0007] (2) According to the total design stockpile height H of the stockyard, a plurality of stockpile heights H' are set according to the experience value and the strength variation of the foundation soil, and before the stockpiling, the height H1 of the first stage stockpiling is confirmed according to the result of the detection before the stockpiling;

[0008] (3) The stockpiling is classified, and the range of the stockpiling, the variation of the stockpile height and the density of the ore are recorded, the placement time and the height of the stockpile are recorded during the placement of the stockpile, and the settlement amount of the foundation is measured;

[0009] (4) When the effective placement time of the stockpile reaches the requirement of the classified stockpiling of the stockyard, if the consolidation degree is not required in the stockpiling of the stage, the next stage stockpiling is started;

[0010] (5) When the consolidation degree of the foundation is required, the ore is unloaded in time, the displacement monitoring point and the survey hole are exposed, the displacement amount and the related geotechnical parameters are measured, and when the shear stability safety factor F≥1.10 of the next stage calculated according to the related geotechnical parameters of the foundation is greater than or equal to 1.10, the next stage stockpiling is started;

[0011] (6) If the foundation strength is insufficient to start the next stage stockpiling, the stockpiling placement time is determined to be extended until the shear stability safety factor meets the requirement, and then the next stage stockpiling is started, and the step (3) is continued until the next stage stockpiling height is the final stage, and the ore is safely stockpiled.

[0012] Further, when the displacement monitoring data indicates that the foundation has signs of instability and destruction, the stockpiling is immediately stopped, and the ore is unloaded in time if necessary, and the stockpiling height is determined separately.

[0013] Further, during the stockpiling, when the settlement monitoring data indicates that the settlement amount of the track of the reclaimer and the reclaimer bed is too large to affect the normal operation of the reclaimer, the track is adjusted in time.

[0014] Further, the stability calculation during the stockpiling uses the following calculation formula:

[0015]

[0016] S i =τ i L i

[0017]

[0018] W i =W oi +W li

[0019]

[0020] In the formula:

[0021] F—allowable value of safety factor for shear stability, F = 1.10;

[0022] i, j—subscripts i, j are the section numbers to distinguish whether the slip surface of the soil slice is in the foundation soil (AB arc) or in the embankment (BC arc) ;

[0023] S i —shear resistance of the i-th slice in the foundation soil (AB arc) (kN), without considering the effect of consolidation;

[0024] S j —shear resistance of the j-th slice in the embankment (BC arc) (kN) ;

[0025] τ i —natural shear strength of the foundation soil layer in which the i-th slice is located (kPa) when the slip surface of the slice is in the foundation soil;

[0026] L i —length of the slip arc of the i-th slice (m) ;

[0027] P j —design tensile force per meter of width (in the direction of the route) of the geotextile layer when the slip surface of the j-th slice is in the embankment (BC arc segment), and the slip surface of the slice intersects the geotextile;

[0028] P T —total sliding force of each slice in the tangential direction of the slip arc (kN) ;

[0029] W—total weight of a slice (subscript i or j) of the slip surface (kN) ;

[0030] α j —angle between the tangent at the midpoint of the slip surface of the j-th slice and the horizontal (degrees) ;

[0031] φ qj , C qj —internal friction angle and cohesion of the fill in which the slip surface of the j-th slice is located when the slip surface of the slice is in the embankment (BC arc segment), which are generally obtained by fast shear test or direct fast shear index;

[0032] W oi , W li —weight of the foundation and embankment fill above the slip surface of the i-th slice (kN) when the slip surface of the slice is in the foundation soil (AB arc segment) ;

[0033] γ—unit weight of the mineral fill above the foundation soil (kN / m 3 ) ;

[0034] L, D - length and width (m) of the stockpile area above the ground soil;

[0035] α - static stockpile angle (degrees) of the mineral material above the ground soil;

[0036] H' - stockpile height (m) of the mineral material above the ground soil.

[0037] Further, the static stockpile angle α of the mineral material is consistent with the internal friction angle φ of the mineral material, which ensures the stability of the stockpile during storage, and during the grading stockpiling process, after the ground consolidation degree reaches 80% under the action of the effective stockpile height H1 of the first working condition, the stockpile is started to the second working condition stockpile height H2, before starting the next level working condition stockpile, the soil quality is investigated, the stability calculation and analysis of the stockyard are carried out according to the relevant physical and mechanical performance index parameters, and whether the next level working condition stockpile can be carried out is evaluated, only when the soil strength is improved to the required value, the next level stockpile is allowed to be transferred, and the cycle is repeated until the final working condition design stockpile height H4 is reached.

[0038] Another technical scheme provided by the application is a ground treatment structure of a soft soil ground stockyard, which comprises ground backfill soil and a retaining wall, the ground backfill soil is stacked with mineral material of multiple levels of design working condition height, the lower part of the mineral material is provided with a sand cushion layer, a blind ditch and a clay impermeable layer, the blind ditch is arranged at the heel foundation of the retaining wall, the side end of the clay impermeable layer is in close contact with the heel of the retaining wall, horizontal displacement monitoring points and settlement monitoring points are arranged on the retaining wall, deep inclinometer points are arranged in the deep part of the retaining wall, level meters are arranged at the horizontal displacement monitoring points and the settlement monitoring points respectively, and an inclinometer is arranged at the deep inclinometer points.

[0039] Further, the ground treatment structure further comprises a reclaimer track arranged in the stockyard, a reclaimer for stacking and taking materials is arranged on the reclaimer track, and horizontal displacement monitoring points, settlement monitoring points and deep inclinometer points are arranged on the reclaimer track and the reclaimer.

[0040] Further, the lower part of the mineral material is fully paved with interlocking floor tiles with strong water permeability, so as to isolate the mineral material from the ground soil.

[0041] Further, the backfill material in the blind ditch is selected from graded gravel with good water permeability, a clay content of less than 5% and a particle size of 30-60 mm, the graded gravel is wrapped with a layer of geotextile with a lap length of not less than 0.5 m, the clay impermeable layer is arranged at the lower part of the geotextile and has a thickness of not less than 500 mm, the depth of the blind ditch is not less than 0.5 m, the bottom slope of the water flow collection direction is not less than 1 ‰, and the blind ditch is inclined from the middle to both ends, and the water in the blind ditch is discharged into the drainage system in the site.

[0042] Further, the mineral material is provided with four levels of stockpile height, and the first level of stockpile height of the mineral material is consistent with the height of the retaining wall.

[0043] The beneficial effects of this invention are:

[0044] (1) It can ensure the normal operation of the stockpile and guarantee that the foundation will not become unstable or damaged under each level of stockpile height, so as to ensure the normal operation of production. Moreover, by using the method of "trading time for money", the soft soil foundation is treated by the large-area stockpile of the overlying mineral material, which saves a foundation treatment cost. Overall, the cost is low and the economy is high. In addition, the stockpile process is continuously monitored, and the next level of stockpile is determined according to the soil strength growth. The whole process is under control.

[0045] (2) The position and elevation of the material reclaimer and its track can be adjusted based on the results of vertical settlement and horizontal displacement monitoring to ensure the normal operation of material stacking and reclaiming;

[0046] (3) The deformation of the material yard can be monitored regularly. Drainage facilities such as sand cushion layer, blind ditch and clay anti-seepage layer are used to reduce and remove the moisture of the ore and backfill soil to avoid serious water accumulation in the retaining wall.

[0047] (4) Make full use of the ore storage capacity of the material yard, and determine the optimal rate of ore pile height increase under the premise of ensuring safety, so as to make the ore pile reach the final design height as soon as possible. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the first working condition of the present invention;

[0049] Figure 2 This is a schematic diagram of the second working condition of the present invention;

[0050] Figure 3 This is a schematic diagram of the third working condition of the present invention;

[0051] Figure 4 This is a schematic diagram of the fourth working condition of the present invention;

[0052] Figure 5 This is a schematic diagram of the drainage section of the present invention;

[0053] Figure 6 This is a schematic diagram of the graded surcharge height and foundation strength of the present invention;

[0054] Figure 7 This is a flowchart of the steps of the present invention;

[0055] Figure 8 This is a schematic diagram illustrating the analysis during the stockpile stability calculation of this invention.

[0056] In the diagram: 1—Column; 2—Retaining wall; 201—Retaining wall facing the ore; 202—Retaining wall heel; 3—Ore; 4—Interlocking paving stones; 5—Sand cushion layer; 6—Blind drain; 601—Crushed stone; 602—Geotextile; 7—Clay anti-seepage layer; 8—Foundation backfill; 9—Reclaimer; 10—Reclaimer track. Detailed Implementation

[0057] The present invention will be further described below with reference to specific embodiments. The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the present invention. In order to better illustrate the specific embodiments of the present invention, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the actual product size. It is understandable for those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] In the description of this invention, it should be noted that the terms "front", "rear", "upper", "lower", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0059] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0060] like Figure 7 As shown, a method for foundation treatment and ore storage management of a soft soil foundation material yard includes the following steps:

[0061] (1) Before stockpiling materials, complete the installation of testing instruments and the measurement and detection work before testing, obtain initial value data such as horizontal displacement, settlement displacement and deep displacement, and conduct the first round of soil survey to obtain relevant geotechnical parameters.

[0062] (2) Confirm the total design load height H based on the total capacity of the ore in the material yard. Based on the experience value and the change in the strength of the foundation soil, set up multiple load levels H'. Before preparing to stockpile the ore, confirm the height H1 of the first level of stockpile based on the results of the pre-stockpile test. It is not necessary to confirm when the ore is stockpiled slowly by trucks or bulldozers.

[0063] (3) Mine shall be piled up according to the prescribed grades, and the extent of the pile, changes in pile height, and density of the ore shall be recorded. For ore piles and pile grades for which foundation displacement is to be monitored, measurements shall be taken as required during the ore pile-up process. If, based on displacement monitoring data, there are signs of foundation instability or failure, ore pile-up shall be stopped immediately; if necessary, ore shall be unloaded in a timely manner, and the pile height shall be determined separately.

[0064] (4) During the placement of the ore pile, record the placement time and height of the ore pile, and measure the settlement of the foundation in accordance with regulations.

[0065] (5) When the effective placement time of the ore pile reaches the classification requirements for the compaction foundation of the stockpile, and there are no requirements for the degree of consolidation of the ore pile at this level, it shall be transferred to the next level of ore pile; when there are requirements for the degree of consolidation of the foundation, the following steps shall be performed:

[0066] (a) When the effective placement time of the ore pile reaches the classification requirements of the compacted foundation ore pile in the material yard, and the ore pile of this level has requirements for the degree of consolidation, the ore should be unloaded in time to expose the displacement monitoring points and exploration holes, and the displacement and related soil and rock parameters should be measured.

[0067] (b) Based on data such as ore stockpile monitoring, foundation settlement monitoring, and foundation geotechnical parameters, a comprehensive analysis and calculation are performed. If the foundation does not experience instability or failure under this load height condition, and the retaining walls, columns, and ground around the stockpile do not show any signs of damage, and the shear stability safety factor F for the next load condition calculated based on the relevant foundation geotechnical parameters is ≥1.10, then the stockpile can be moved to the next load height. If the foundation strength is insufficient and the stockpile cannot be moved to the next load height, then the required extended stockpile placement time should be determined. When there are production requirements, a new stockpile height that can be stockpiled (i.e., adding an intermediate stockpile level) should be determined.

[0068] (c) After moving to the next level of stacking, continue to manage from step (3); when the next level of stacking is the final level, after safely stacking according to step (3), the storage management work of the area is completed.

[0069] (d) If the settlement of the reclaimer and the reclaimer track is too large, affecting the normal operation of the reclaimer, the track should be adjusted in time according to the settlement monitoring data.

[0070] (e) If an undesirable material site foundation instability and sliding failure accident occurs, a special investigation, analysis, research and handling should be carried out.

[0071] When stockpiling mineral materials, the material is typically piled up for a short period of time, and the soil cannot solidify instantly. Therefore, if... Figure 8 As shown, the stability calculation during stockpiling uses the following formula:

[0072]

[0073] S i =τ i L i

[0074]

[0075] W i =W oi +W li

[0076]

[0077] In the formula:

[0078] F—Shear stability safety factor, allowable value F = 1.10;

[0079] i, j — Subscripts i and j are the strip numbers that distinguish whether the slip surface at the bottom of the soil strip is within the foundation soil layer (AB arc) or within the material pile (BC arc);

[0080] S i —The shear resistance (kN) of the i-th strip sliding body in the foundation soil (AB arc), without considering consolidation;

[0081] S j —Shear resistance (kN) of the j-th soil strip sliding body within the material pile (BC arc);

[0082] τ i —When the slip surface of the i-th soil strip is located within the foundation soil, the natural vane shear strength (kPa) of the foundation soil layer where the slip surface of the soil strip is located;

[0083] L i —The length of the slip arc at the slip surface of the i-th soil strip (m);

[0084] P j —When the slip surface of the j-th soil strip is inside the material pile (BC arc segment), if the slip surface of the soil strip intersects with the geotextile, then Pj is the design tensile force (kN) per meter width (along the route direction) of the geotextile layer.

[0085] P T —The total sliding force of each soil strip in the tangential direction of the slip arc (kN);

[0086] W—The total weight (kN) of a soil strip (subscript can be i or j) of the slip body;

[0087] α j —The angle (in degrees) between the tangent at the midpoint of the slip surface at the bottom of the j-th soil strip and the horizontal plane;

[0088] φ qj C qj —When the slip surface of the j-th soil strip is within the material pile (BC arc segment), these are the internal friction angle and cohesion of the fill material at the slip surface of the soil strip, which are generally determined by the quick shear test or direct quick shear index.

[0089] W oi W li —When the slip surface of the i-th soil strip is inside the foundation soil (AB arc segment), the values ​​are the self-weight of the foundation soil and the self-weight of the embankment fill material in the soil strip above the slip surface (kN), respectively.

[0090] γ—Unit weight of mineral material above the foundation soil (kN / m³) 3 );

[0091] L, D — Length and width (m) of the material stockpile area above the foundation soil;

[0092] α—The static surcharge angle (degrees) of the mineral material above the foundation soil;

[0093] H'—Height of the ore packing above the foundation soil (m).

[0094] like Figures 4-5 The foundation treatment structure of a soft soil foundation material yard shown includes foundation backfill soil 8 and retaining wall 2. The foundation backfill soil 8 is piled with mineral material 3 at multiple design working heights. The mineral material 3 is provided with a sand cushion layer 5, a blind drain 6 and a clay anti-seepage layer 7 below it. The blind drain 6 is set at the foundation of the retaining wall heel 202 to drain surface water and prevent the foundation soil from being soaked in water, which could lead to foundation softening, uneven settlement and other phenomena. The side end of the clay anti-seepage layer 7 is in close contact with the retaining wall heel 202. Horizontal displacement monitoring points and settlement monitoring points are set on the retaining wall 2. Deep inclinometer points are set in the deep layer of the retaining wall 2. Level instruments are set at the horizontal displacement monitoring points and settlement monitoring points, and inclinometers are set at the deep inclinometer points.

[0095] The foundation treatment structure also includes a reclaimer track 10 laid out in the material yard, on which reclaimers 9 are installed for stockpiling and reclaiming materials. Both the reclaimer track 10 and the reclaimers 9 are equipped with horizontal displacement monitoring points, settlement monitoring points, and deep inclination measurement points. During the loading process, the foundation soil will deform, affecting the surrounding reclaimers and tracks, leading to deflection and settlement. By setting monitoring points and reasonably adjusting the stockpiling height, the entire structure remains in a stable and controlled state.

[0096] The lower part of the ore material 3 is fully covered with interlocking paving bricks 4 with high permeability and a thickness of 100mm. Sea sand is used to fill the gaps between the paving bricks to isolate the ore material 3 from the foundation backfill soil 8 and to accelerate the drainage of the ore material and reduce the moisture content of the ore material.

[0097] To prevent waterlogging and secondary pollution of the ore in the material shed, highly permeable interlocking paving bricks are laid under the ore to isolate it from the foundation soil and reduce its moisture content. The sand cushion layer 5 at the top of the blind drain 6 is flush with the bottom of the interlocking paving bricks 4. The backfill material in the blind drain 6 is graded crushed stone 601 with good permeability, a mud content of less than 5%, and a particle size of 30-60mm. The graded crushed stone 601 is wrapped with a layer of woven geotextile 602 with an overlap length of not less than 0.5m.

[0098] Blind Drain 6 has a bottom width of 0.8-1.0m, a side slope of 1:0.5, and a depth of 0.8-1.0m. The bottom slope in the direction of water flow convergence is not less than 1‰, sloping from the middle to both sections. The water in Blind Drain 6 is discharged into the site's drainage system.

[0099] A clay impermeable layer 7 with a thickness of not less than 500 mm is set under the geotextile 602. The side end of the clay impermeable layer 7 should be in close contact with the retaining wall heel 202 to prevent the geotextile from seeping into the blind ditch and reduce the drainage effect of the surface water.

[0100] Monitoring points should be located in easily observable areas to prevent obstruction by mineral deposits. The bottom of deep horizontal displacement points should be embedded at least 1 meter into strongly weathered rock. During monitoring, if large-scale settlement, severe uneven settlement, or severe cracks are detected, or if there are sudden increases or decreases in ground load near the foundation, significant water accumulation around the foundation, or prolonged continuous rainfall, the monitoring frequency should be increased, and a safety emergency plan should be implemented.

[0101] The embodiment provides a method for foundation treatment and ore storage management of a soft soil foundation material yard, such as... Figures 1-6 As shown, the total capacity of the ore yard is currently determined by the producer, with a total design shovel height H. Based on empirical values ​​and changes in foundation soil strength, multiple shovel heights H' (i.e., multiple working condition heights, which can be determined beforehand) are set to achieve the total design shovel height. The predicted foundation soil strength φ under each working condition is mainly derived from these tiered shovel heights and stability coefficients. qj C qj During the actual stockpiling process, geological surveys were conducted to determine the relevant geotechnical parameters under each load level H', including the measured φ. qj C qjThe load should not be lower than the predicted value, and the stability should be ≥1.10. The static load angle α of the ore should be consistent with the internal friction angle φ of the ore to ensure the stability of the load during storage. The ore 3 is set with four load heights. After the foundation consolidation reaches 80% under the effective load height H1 of the first working condition, the load is started to the load height H2 of the second working condition. Before starting the load of the next working condition, a soil survey should be carried out, and the stability of the material yard should be verified and analyzed according to the relevant physical and mechanical performance parameters. It should be assessed whether the load of the next working condition can be carried out. Only after the soil strength increases to the required value is it allowed to move to the next load height. This cycle is repeated until the final working condition design load height H4 is reached. The relationship between the graded load height and the foundation strength of this invention is as follows: Figure 6 As shown, in the first working condition, the ore-facing pile height H1 near the retaining wall should be consistent with the retaining wall height. The width of the ore pile at this location should be calculated based on the static load angle α and the pile height H1, and the pile should be stacked upwards in a stepped manner with the static load angle α up to H2. The stepped pile heights for the second working condition are H2 and H3 respectively. In the third working condition, the top of the trapezoidal pile is stacked flat up to H3. In the fourth working condition, the top of the trapezoidal pile is stacked flat up to H4. The ore is piled up in multiple working conditions according to the process design. The pile height for each working condition should maintain sufficient effective storage time to ensure that the consolidation degree of the foundation soil and the excess pore water dissipation degree meet the standards required for the stability verification of the next load. During the pile-up process, the monitoring frequency should be increased, and the pressure should be released and reduced in time if problems are found. The ore should be preloaded evenly, and the upper load should be evenly distributed to avoid uneven settlement due to concentrated loads. The upper stepped distribution pile should not be changed to a triangular concentrated pile.

[0102] The invention will be further described below with reference to specific embodiments. The geological strata of the site for this project, from top to bottom, are: plain fill, dredged silty clay, dredged fine sand, fine sand, silty clay, strongly weathered argillaceous siltstone, and moderately weathered argillaceous siltstone. The material shed is 840m long, 96m span, and has a maximum height of 45m. The material shed contains ore powder with a density of 23-28 kN / m³. 3 (Design value: 27.6 kN / m) 3 The static stacking angle is 36°-41° (design value is 38°), and the maximum design stacking height is 14m.

[0103] In order to measure the settlement and displacement of each soil and rock layer under various loading levels, it is necessary to conduct comprehensive monitoring of the entire material yard. At the same time, in order to focus the monitoring work, a representative area is selected within the site for experimental testing. The results will serve as the basis for large-scale ore stockpiling. Therefore, the ore storage management design of this material yard adopts the principle of combining key monitoring and comprehensive monitoring.

[0104] A section of land (at least 50m in length) was selected as the test section, divided into four loading conditions. The height of each loading level was H1=5m, H2=3m, H3=3m, and H4=3m. In the first condition, the loading height in the area adjacent to the retaining wall should be consistent with the height of the retaining wall. The loading width of the 5m high ore pile was 11m, and it was loaded upwards in a stepped manner with a static loading angle of 38° to 8m. In the second condition, the heights of the stepped piles were 8m and 11m respectively. In the third condition, the top of the trapezoidal pile was loaded flat to 11m. In the fourth condition, the top of the trapezoidal pile was loaded flat to 14m. The loading height can be adjusted appropriately later according to the changes in the strength of the foundation soil under the loading conditions.

[0105] Based on a shear stability safety factor F≥1.10, inversion calculations were performed to deduce the minimum values ​​of cohesion C and internal friction angle φ under direct shear and rapid shear tests at each load level. Subsequent soil surveys required that the measured parameters not be lower than these values ​​before proceeding to the next load condition. Cohesion C and internal friction angle φ gradually increase with loading time. These values ​​were reasonably predicted based on the preliminary investigation report and relevant soil and rock parameters, and then tested to ensure they met stability requirements.

[0106] Based on the calculated reasonable value, S j Substituting the first formula to meet the overall stability requirements, the two calculated parameters are used as predicted values, and then the actual values ​​of the two parameters from the soil survey during the stockpiling process are used for verification.

[0107] In this embodiment, the stability coefficient and settlement of the stockpile are shown in Table 1, and the predicted values ​​of the geotechnical parameters after the stockpile preloading are shown in Table 2.

[0108] Table 1. Statistical Results of Calculation of Stability Coefficient and Settlement of Mine Shed Stockpile

[0109]

[0110] Table 2 Predicted values ​​of geotechnical parameters after preloading of stockpiled materials.

[0111]

[0112] In this embodiment, the monitoring frequency is once every 2 days during the stockpiling period, once every 4 days within one month after the stockpiling ends, once per week when the displacement tends to stabilize, and once per month when the displacement is stable. An early warning should be issued promptly if the deformation rate of horizontal displacement, vertical displacement, or deep horizontal displacement exceeds 3 mm / d, or if the cumulative value of horizontal and vertical displacement exceeds 20 mm, or the cumulative value of deep displacement exceeds 30 mm.

[0113] During the monitoring process, if large-scale settlement, severe uneven settlement, or severe cracks are found, or if there is a sudden increase or decrease in the ground load near the foundation, a large amount of water accumulation around the foundation, or prolonged continuous rainfall, the monitoring frequency should be increased and a safety emergency plan should be implemented.

[0114] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for ground treatment and stockpile management of a soft ground stockpile, characterized by, It comprises the following steps: (1) Before stacking, complete the embedding of the testing instrument and the measurement and detection before testing, obtain the initial value data of horizontal displacement, settlement displacement and deep displacement, and conduct the first round of soil quality investigation to obtain relevant geotechnical mechanics parameters; (2) Confirm the total design stacking height H according to the total capacity of the stockyard, set multiple stacking levels H' according to the empirical value and the strength variation of the foundation soil, and confirm the height H1 of the first stacking level according to the results of the detection before stacking; (3) Stack the ore according to the classification, record the stacking range, the change of stacking height and the specific gravity of the ore, record the placement time and height of the ore stack during the placement of the ore stack, and measure the settlement of the foundation; (4) When the effective placement time of the ore stack reaches the requirement of the classification of the stockyard compaction foundation, the next stacking level is entered if there is no requirement for the consolidation degree of the foundation; (5) When there is a requirement for the consolidation degree of the foundation, the ore is unloaded in time to expose the displacement monitoring points and the survey holes, the displacement and the relevant geotechnical parameters are measured, and the shear stability safety factor F≥1.10 of the next working condition calculated according to the relevant geotechnical parameters of the foundation is entered into the next stacking level; (6) If the foundation strength is insufficient to enter the next stacking height, the stacking placement time is determined to be extended until the shear stability safety factor meets the requirement, and then the next stacking level is entered, and the step (3) is continued until the next stacking height is the final level, and the ore is safely stacked.

2. The foundation treatment and stockpile management method for soft ground foundations according to claim 1, characterized in that, When there is a sign of instability and destruction of the foundation according to the displacement monitoring data in the step (3), the stacking is immediately stopped, and the ore is unloaded in time if necessary, and the stacking height is determined.

3. The foundation treatment and stockpile management method for soft ground foundations according to claim 1, characterized in that, During the stacking, the track settlement of the reclaimer and the reclaimer bed is too large according to the settlement monitoring data, which affects the normal operation of the reclaimer, and the track is adjusted in time.

4. The foundation treatment and stockpile management method for soft ground foundations according to claim 1, characterized in that, The following calculation formula is used for the stability calculation during the stacking: S i = τ i L i W i = W oi + W li In the formula: F is the shear stability safety factor; i and j are the subscripts i and j that distinguish the sliding surface at the bottom of the soil strip from the soil layer and the ore stack; S i - the shear resistance of the i-th slice in the soil mass, not taking into account the consolidation effect; S j - the shear resistance of the jth soil slice within the heap. τ i — when the slip surface of the ith slice is in the foundation soil, the natural vane shear strength of the soil layer in which the slip surface of the slice is located; L i — Length of slip arc at slip surface of ith slice P j — When the slip surface of the jth slice is within the heap, if the slip surface of the slice intersects the geotextile installed, P j is the design tension per meter width of the geotextile for this layer. P T — the sum of the downslide forces of each soil strip in the direction of the tangent to the sliding arc; W is the total weight of a soil strip, and the subscript is i or j; a j — the angle between the tangent at the midpoint of the bottom slip surface of the jth strip and the horizontal plane; φ qj , C qj — When the slip surface of the jth slice is in the stockpile, the internal friction angle and cohesion of the material at the slip surface of the slice are generally determined by the quick shear test or direct quick shear index, respectively. W oi 、W li — When the slip surface of the ith slice is in the foundation soil, the self-weight of the foundation above the slip surface in the slice and the self-weight of the embankment fill, respectively; γ is the specific gravity of the ore above the foundation soil; L and D are the length and width of the stacking area of the ore above the foundation soil; α is the static stacking angle of the ore above the foundation soil; H' is the stacking height of the ore above the foundation soil.

5. The foundation treatment and stockpile management method for soft ground foundations according to claim 1, characterized in that, The static stacking angle α of the ore is consistent with the internal friction angle φ of the ore to ensure the stacking stability during the storage, and after the consolidation degree of the foundation reaches 80% under the effective stacking height H1 of the first working condition during the classified stacking, the stacking is started to the second working condition stacking height H2, the soil quality investigation is conducted before the start of the next working condition stacking, the stability calculation and analysis of the stockyard are conducted according to the relevant physical and mechanical performance index parameters, and whether the next working condition stacking can be conducted is evaluated, and only when the soil strength is increased to the required value, the next stacking height is allowed to be entered, and the cycle is repeated until the final working condition design stacking height H4 is reached.

6. A foundation treatment structure of a soft soil foundation stockyard, which is implemented based on the foundation treatment and stockpile management method of a soft soil foundation stockyard according to any one of claims 1 to 5, characterized in that, The application relates to a foundation treatment structure, which comprises a foundation backfill soil (8) and a retaining wall (2), wherein the foundation backfill soil (8) is stacked with mine materials (3) of multiple-stage design working conditions, the lower part of the mine materials (3) is provided with a sand cushion layer (5), a blind ditch (6) and a clay impermeable layer (7), the blind ditch (6) is arranged at the foundation of a retaining wall heel (202), the side end of the clay impermeable layer (7) is in close contact with the retaining wall heel (202), the retaining wall (2) is provided with horizontal displacement monitoring points and settlement monitoring points, the deep part of the retaining wall (2) is provided with deep inclinometer points, the horizontal displacement monitoring points and the settlement monitoring points are respectively provided with level meters, and the deep inclinometer points are provided with inclinometers.

7. A foundation treatment structure for a soft ground site according to claim 6, wherein: The foundation treatment structure further comprises a material taking machine track (10) arranged in a material yard, the material taking machine track (10) is provided with a material taking machine (9) for stacking and taking materials, and the material taking machine track (10) and the material taking machine (9) are both provided with horizontal displacement monitoring points, settlement monitoring points and deep inclinometer points.

8. The foundation treatment structure for soft ground sites according to claim 6, wherein: The lower part of the mine materials (3) is fully paved with interlocking floor tiles (4) with high water permeability, so as to isolate the mine materials (3) from the foundation backfill soil (8), and the sand cushion layer (5) on the top of the blind ditch (6) is flush with the bottom of the interlocking floor tiles (4).

9. The foundation treatment structure for soft ground sites according to Claim 6, characterized by: The backfill material in the blind ditch (6) is selected from graded gravel (601) with good water permeability and a mud content lower than 5% and a particle size of 30-60 mm, the graded gravel (601) is wrapped with a layer of geotextile (602) with a lap length not less than 0.5 m, the clay impermeable layer (7) is arranged at the lower part of the geotextile (602) and has a thickness not less than 500 mm, the depth of the blind ditch (6) is not less than 0.5 m, the bottom slope of the water flow collection direction is not less than 1 ‰, and the blind ditch (6) is inclined from the middle to two sections, and the water in the blind ditch (6) is discharged into a site drainage system.

10. The foundation treatment structure for soft ground sites according to Claim 6, wherein: The mine materials (3) are provided with four-stage stacking heights, and the first-stage stacking height of the mine materials (3) is consistent with the height of the retaining wall (2).

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