Dump base bearing capacity judgment method based on Bocinnike solution

Abstract

The invention discloses a method for judging the bearing capacity of a base of a refuse dump based on a Bocinnike solution, which is characterized by comprising the following steps of: acquiring the filler weight gamma t of the refuse dump, the bearing capacity characteristic value fak of each soil layer of the base and the foundation bearing capacity correction coefficient eta i; the method comprises the following steps: on the basis of a Bocinnike solution, approximating a slope area of the waste dump as a triangular distribution load, and then adopting a manner of overlapping a rectangular load and a triangular load to obtain load distribution of a slope toe area; based on the obtained bearing capacity characteristic values of the soil layers of the base, depth correction is conducted according to the thicknesses of the soil layers, and the bearing capacity of the soil layers below the slope toe is obtained; and comparing the total load considering the safety factor at each depth position below the base with the bearing capacity, judging whether the bearing capacity of the foundation meets the requirement or not, and calculating the bearing capacity value needing to be improved in the processing area by improving the characteristic value of the stratum bearing capacity of the unsatisfied area to meet the requirement. The method can solve the problem that the spatial form of the waste dump is not considered in the current foundation bearing capacity determination.

Description

Technical Field

[0001] This invention relates to the field of open-pit mine spoil heap technology, specifically to a method for determining the bearing capacity of spoil heap foundation based on the Businsk solution. Background Technology

[0002] With the development of open-pit mines, a large amount of waste rock is generated that needs to be stockpiled, resulting in an increasing number of large spoil heaps. Large spoil heaps are characterized by high stockpiling heights and limited site selection due to factors such as haulage distance and terrain conditions. Under these conditions, accurately determining the required foundation bearing capacity of the spoil heap has a significant impact on its stability and construction investment.

[0003] On the one hand, major safety accidents frequently occur after spoil heaps are built due to insufficient foundation bearing capacity. On the other hand, due to the inability to accurately determine the foundation bearing capacity requirements of spoil heaps, some projects have wasted a lot of time and money on foundation treatment, and even had to change sites as a result.

[0004] Currently, many data and engineering practices directly use the unit weight of the fill material in the highest area of ​​the spoil heap multiplied by a certain safety factor to calculate the required foundation bearing capacity. This method does not consider the spatial morphology of the spoil heap. In the internal areas of the foundation, due to the load from the spoil heap itself, the characteristic value of the foundation bearing capacity, after correction, can match the bearing capacity determined by this method, and there will be no situation where the bearing capacity is insufficient. However, in the areas near the slope, where there is no large-area spoil heap, the foundation can only provide limited bearing capacity. Calculating the required foundation bearing capacity using the same method will result in an abnormally high bearing capacity requirement, causing problems where even conventional foundation treatment methods cannot meet the design requirements.

[0005] Therefore, in order to solve the above problems, this paper proposes a method for determining the bearing capacity of the foundation of spoil heaps based on the Businsk solution. Summary of the Invention

[0006] The purpose of this invention is to provide a method for determining the bearing capacity of spoil heap foundation based on the Businsk solution, which solves the problem that the spatial morphology of spoil heap is not considered in the current determination of foundation bearing capacity.

[0007] To achieve the above-mentioned technical effects, the present invention is implemented through the following technical solution: a method for determining the bearing capacity of a spoil heap foundation based on the Bussinisk solution, characterized by comprising the following steps:

[0008] S1. Obtain the unit weight γ of the spoil heap fill. t and the characteristic value f of the bearing capacity of each soil layer at the base. ak and foundation bearing capacity correction factor η i ;

[0009] S2. Based on the Businsk solution, the slope area of ​​the spoil heap is approximated as a triangular load distribution. Then, the load distribution in the toe area is obtained by superimposing the rectangular load and the triangular load.

[0010] S3. Based on the characteristic values ​​of the bearing capacity of each soil layer of the foundation obtained from S1, and with depth correction according to the thickness of each soil layer, the bearing capacity of the soil layer below the slope toe is obtained.

[0011] S4. Compare the total load and bearing capacity at each depth below the foundation, taking into account the safety factor, to determine whether the foundation bearing capacity meets the requirements and to determine the range of non-compliance.

[0012] S5. When the foundation bearing capacity safety factor does not meet the requirements, the bearing capacity value of the area that does not meet the requirements is increased to meet the requirements, and the bearing capacity value of the area to be treated is calculated.

[0013] Furthermore, in S1, the unit weight γ of the spoil heap fill is obtained. t and the characteristic value f of the bearing capacity of each soil layer at the base. ak and foundation bearing capacity correction factor η i Specifically, the following was done: The unit weight γ of the spoil heap fill was obtained based on survey and geotechnical test data. t and the characteristic value f of the bearing capacity of each soil layer at the base. ak Foundation bearing capacity correction factor η i .

[0014] Furthermore, in S2, the load distribution in the slope toe area is obtained by superimposing rectangular and triangular loads as follows:

[0015] The maximum load on the spoil heap is calculated as shown in equation (1):

[0016] P = γ t H t (1)

[0017] In the formula: γ t Unit weight of fill material for spoil heap; H t The height of the spoil heap;

[0018] Based on the Businsk solution, the additional load σ generated by the fill material at the bottom of the slope area is calculated as a triangular load. z1 As shown in equation (2):

[0019]

[0020] Based on the Businskews solution principle, the additional load σ generated by the fill material at the bottom of the slope after dividing the rectangular load at the top of the slope is calculated. z2 As shown in equation (3):

[0021]

[0022] In equations (2) and (3): b is the length from the bottom of the slope to the top of the slope; l is the length from the origin of the slope bottom direction to the boundary of the spoil heap; γ t Unit weight of fill material for spoil heap; H t The height of the spoil heap is represented by x, y, and z; x, y, and z represent the spatial location of the fill material; the origin of the coordinate system is located at the midpoint of the slope baseline, the x-direction is perpendicular to the slope baseline through the origin, the y-direction is parallel to the slope baseline through the origin, and the z-direction is the depth below the midpoint of the slope baseline.

[0023] At this time, the total additional load σ generated by the spoil heap in the slope toe area is... z As shown in equation (4):

[0024] σ z =σ z1 +σ z2 (4)

[0025] Calculate the self-weight load σ of the soil and rock layer at the slope toe. cz As shown in equation (5):

[0026]

[0027] In the formula: n is the number of soil and rock layers above the calculation depth; γ i To calculate the unit weight of the soil and rock layers above the depth, the buoyant unit weight of the permeable layer below the groundwater level is used; h i To calculate the thickness of each soil layer above the depth;

[0028] At this point, the total load P on the foundation soil layer at the toe of the slope is as shown in equation (6):

[0029] P = σ z +σ cz (6)

[0030] Furthermore, in S3, the correction formula for depth correction based on the thickness of each soil layer is shown in equation (7):

[0031]

[0032] In the formula: f aki η represents the characteristic value of the bearing capacity of each soil layer below the foundation. i γ is the correction factor for the bearing capacity of each soil layer below the foundation; i To calculate the unit weight of the soil and rock layers above the depth, the buoyant unit weight of the permeable layer below the groundwater level is used; h i To calculate the thickness of each soil layer above the depth.

[0033] Furthermore, in S4, the additional loads and bearing capacities at various depths below the foundation are compared, as shown in Equation (8):

[0034] f a≥K×P(8)

[0035] In the formula: f a denoted as ρ, where ρ is the soil bearing capacity; K is the foundation bearing capacity safety factor; and P is the total load on the soil and rock layer at the slope toe.

[0036] Furthermore, in S4, the determination and adjustment of the foundation bearing capacity safety factor is as follows:

[0037] When the bearing capacity requirement shown in Equation (8) is met at different depths of the foundation, the bearing capacity of the spoil heap foundation meets the requirements;

[0038] When the bearing capacity requirements shown in Equation (8) are not met at different depths of the foundation, the range of soil layers to be treated and the required increase in bearing capacity of each soil layer are determined by adjusting the characteristic values ​​of bearing capacity of each soil layer until the conditions of Equation (8) are met.

[0039] The beneficial effects of this invention are:

[0040] 1. This invention is based on the spatial morphology of the spoil heap and determines whether the bearing capacity of different areas of the spoil heap meets the spoil heap requirements. The spoil heap construction is guided by the determination results. Only areas that do not meet the bearing capacity requirements need to be treated according to the determination results, without the need for large-scale foundation treatment of these areas. This not only ensures the safety of the spoil heap, but also saves a lot of foundation treatment costs.

[0041] 2. Based on the Businsk solution, this invention takes into account the spatial morphological characteristics of the spoil heap, superimposes the loads in different areas of the spoil heap, and accurately analyzes the additional load on the foundation. This enables accurate analysis of the additional load in the outer area of ​​the spoil heap, and further obtains the total load distribution at different depths. The load distribution obtained is more accurate than that obtained by traditional methods, and solves the problem of seriously overestimating the load obtained by traditional methods.

[0042] 3. This invention employs a depth-correction method based on bearing capacity characteristic values ​​to determine the bearing capacity of the foundation, thereby achieving accurate analysis of bearing capacity at different depths and avoiding the underestimation and waste of bearing capacity by traditional methods.

[0043] 4. This invention enables precise analysis of load distribution and bearing capacity distribution, allowing for comparative analysis of load and bearing capacity in different regions. It identifies regions where bearing capacity needs to be increased and, based on qualitative calculations, determines the specific value that needs to be increased in these regions. This solves the problem of inaccuracy in traditional methods regarding the regions to be processed and the values ​​that need to be increased. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic cross-sectional view of the foundation bearing capacity verification of the spoil heap in Embodiment 1 of the present invention;

[0046] Figure 2 This is a schematic diagram illustrating the calculation of triangular loads in the slope area of ​​the spoil heap and rectangular loads in the area behind the slope in Embodiment 1 of the present invention.

[0047] Figure 3 This is a diagram showing the distribution of additional loads below the foundation of the spoil heap slope in Embodiment 1 of the present invention.

[0048] Figure 4 This is a diagram showing the total load distribution at the base of the spoil heap slope in Embodiment 1 of the present invention.

[0049] Figure 5 This is a diagram showing the bearing capacity of the foundation at the toe of the spoil heap in Embodiment 1 of the present invention.

[0050] Figure 6 This is a comparison diagram of the total load and bearing capacity of the spoil heap slope foundation in Embodiment 1 of the present invention;

[0051] Figure 7 This is a diagram showing the bearing capacity distribution of the spoil heap after foundation treatment in Embodiment 1 of the present invention. Detailed Implementation

[0052] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Example 1

[0054] This embodiment applies a method for determining the bearing capacity of spoil heap foundations based on the Bussinisk solution to a real-world scenario, as detailed below:

[0055] like Figure 1 As shown, the selected spoil heap has a step slope ratio of 1:1.5, an overall slope angle of 22°, a spoil heap height of 80m, a slope area width of b = 200m, and a slope length of 2×l = 160m; the spoil heap is divided into 4 steps, each step being 20m high.

[0056] The soil and rock layers at the base of the spoil heap, from top to bottom, are: clay layer 1, clay layer 2, strongly weathered limestone 3, and moderately weathered limestone 4; the relevant parameters of each soil and rock layer are shown in Table 1 below.

[0057] Rock and soil names Thickness (m) <![CDATA[Heavy (kN / m 3 )]]> Bearing capacity characteristic value (kPa) Depth correction factor waste rock / 21 / / Silty clay layer 1 10 19 170 1.0 Strongly weathered sandstone 3 5 22 400 / Moderately weathered sandstone 4 30 24 1000 /

[0058] Table 1

[0059] Based on the Businsk solution, the slope area of ​​the spoil heap is approximated as a triangular distributed load, and the calculation principle is as follows: Figure 2 As shown;

[0060] The additional load generated by the slope fill at the bottom of the slope is calculated as shown in equation (1):

[0061]

[0062] Specifically, calculate the additional load generated by the slope fill material at Z=0m at the bottom of the slope:

[0063]

[0064] Calculate the additional load generated by the slope fill material at the bottom of the slope when Z = 1m:

[0065]

[0066] Calculate the additional load generated by the slope fill material at the bottom of the slope when Z = 2m:

[0067]

[0068] Using the above method, calculations were performed sequentially from the surface to the bottom of the layer affecting the spoil heap. The data from Table 1 were then substituted into the calculations up to the bottom of the strongly weathered layer, i.e., 15m below the surface. The calculation results are summarized in Table 2 below.

[0069]

[0070]

[0071] Table 2

[0072] Based on the Businskew solution principle, the load of the spoil heap is distributed entirely after the slope bottom according to equation (2), and the load of the slope area is deducted. The distribution principle is as follows: Figure 2 As shown;

[0073] P = γ t H t (2)

[0074] The additional load generated by the fill material at the bottom of the slope after dividing the rectangular load is calculated is shown in equation (3):

[0075]

[0076] Calculate the additional load generated by the fill material at Z=0m at the bottom of the slope after the top of the slope:

[0077]

[0078] σ z20 =σ z2a0 -σ z2b0 =0

[0079] The additional load generated by the fill material at the bottom of the slope (Z=1m) after the top of the slope is calculated using the following formula:

[0080]

[0081]

[0082] σ z21 =σ z2a1 -σ z2b1 =0

[0083] Using the above method, calculations were performed sequentially from the surface to the bottom of the layer affecting the spoil heap. The data from Table 1 were then substituted into the calculations up to the bottom of the strongly weathered layer, i.e., 15m below the surface. The calculation results are summarized in Table 3 below.

[0084] <![CDATA[Z 2i (m)]]> <![CDATA[σ z21 (kPa)]]> <![CDATA[Z 2i (m)]]> <![CDATA[σ z21 (kPa)]]> <![CDATA[Z 2i (m)]]> <![CDATA[σ z21 (kPa) <!-- 5 -->]]> 0 0 6 0 12 0 1 0 7 0 13 0 2 0 8 0 14 0 3 0 9 0 15 0 4 0 10 0 5 0 11 0

[0085] Table 3

[0086] The total additional stress generated at different depths at the bottom of the slope in the spoil heap is as described in equation (4).

[0087] σ z =σ z1 +σ z2

[0088] Substituting the data from Tables 2 and 3 into the result formula (4), the summary is shown in Table 4 below:

[0089]

[0090]

[0091] Table 4

[0092] Appendix based on Table 4 Figure 3 The distribution of additional stress at different depths at the bottom of the spoil heap is obtained; the total load at different depths is calculated as shown in equation (5).

[0093]

[0094] Substituting the data from Table 4 into equation (5), the results are summarized in Table 5 below:

[0095] <![CDATA[Z i (m)]]> <![CDATA[σ z1 (kPa)]]> <![CDATA[Z i (m)]]> <![CDATA[σ z1 (kPa)]]> <![CDATA[Z i (m)]]> <![CDATA[σ z1 (kPa)]]> 0 0 6 130.00 12 259.69 1 25.27 7 151.64 13 281.26 2 43.35 8 173.27 14 302.81 3 65.02 9 194.90 15 324.34 4 86.68 10 216.51 5 108.34 11 238.10

[0096] Table 5

[0097] Appendix based on Table 5 Figure 4 Get Z i -P i Distribution map.

[0098] The bearing capacity of the foundation is calculated using the following formula:

[0099]

[0100] In the formula: f ak η is the characteristic value of the bearing capacity of the foundation soil layer. i This is a correction factor for the bearing capacity of the foundation soil layer. Calculate the bearing capacity at different depths below the ground level at the slope toe, and the bearing capacity at the ground surface:

[0101] f a0 =f ak =170kPa

[0102] Bearing capacity at 1m below the ground surface:

[0103]

[0104] Calculate sequentially up to 10m below the ground surface:

[0105]

[0106] The calculation results of bearing capacity at different depths at the bottom of the spoil heap are summarized in Table 6 below:

[0107] <![CDATA[Z i (m)]]> <![CDATA[f ai (kPa)]]> <![CDATA[Z i (m)]]> <![CDATA[f ai (kPa)]]> <![CDATA[Z i (m)]]> <![CDATA[f ai (kPa)]]> 0 170 6 284 12 612 1 189 7 303 13 634 2 208 8 322 14 656 3 227 9 341 15 678 4 246 10 360 5 265 11 490

[0108] Table 6

[0109] Appendix based on Table 6 Figure 5 Get Zi-f ai Distribution map.

[0110] In this embodiment, a safety factor K = 2 is used. The total stress in Table 5 is multiplied by 2 and compared with the bearing capacity shown in Table 6. Additional calculations are then performed. Figure 6 It can be seen that the total stress is distributed in the 7-10m silty clay layer (attached). Figure 6 The area to be filled exceeds the bearing capacity range, and the bearing capacity of this area does not meet the requirements, so foundation treatment is required.

[0111] Foundation treatment alters the bearing capacity distribution by increasing the characteristic value of the bearing capacity. When the bearing capacity curve completely encloses the total stress line, the treated foundation meets the requirements. In this example, increasing the characteristic value of the bearing capacity of the silty clay layer from 170 kPa to 245 kPa satisfies the requirements. The bearing capacity after treatment is shown in the attached figure. Figure 7 (The bearing capacity curve completely encloses the total stress curve). Therefore, it is determined that the silty clay layer requires foundation treatment, and the characteristic value of the bearing capacity of this layer needs to be increased from 170 kPa to 245 kPa after treatment.

Claims

1. A method for determining the bearing capacity of a spoil heap foundation based on the Businskew solution, characterized in that, Includes the following steps: S1. Obtain the unit weight γ of the spoil heap fill. t and the characteristic value f of the bearing capacity of each soil layer at the base. ak Foundation bearing capacity correction factor η i ; S2. Based on the Businsk solution, the slope area of ​​the spoil heap is approximated as a triangular load distribution. Then, the load distribution in the toe area is obtained by superimposing the rectangular load and the triangular load. S3. Based on the characteristic values ​​of the bearing capacity of each soil layer of the foundation obtained from S1, and with depth correction according to the thickness of each soil layer, the bearing capacity of the soil layer below the slope toe is obtained. S4. Compare the total load and bearing capacity at each depth below the foundation, taking into account the safety factor, to determine whether the foundation bearing capacity meets the requirements and to determine the range of non-compliance. S5. When the foundation bearing capacity safety factor does not meet the requirements, the bearing capacity value of the area that does not meet the requirements is increased to meet the requirements, and the bearing capacity value of the area to be treated is calculated.

2. The method for determining the bearing capacity of a spoil heap foundation based on the Bussinisk solution according to claim 1, characterized in that, In S1, the unit weight γ of the spoil heap fill is obtained. t and the characteristic value f of the bearing capacity of each soil layer at the base. ak and foundation bearing capacity correction factor η i Specifically, the following was done: The unit weight γ of the spoil heap fill was obtained based on survey and geotechnical test data. t and the characteristic value f of the bearing capacity of each soil layer at the base. ak Foundation bearing capacity correction factor η i .

3. The method for determining the bearing capacity of a spoil heap foundation based on the Bussinisk solution according to claim 1, characterized in that, In S2, the load distribution in the slope toe area is obtained by superimposing rectangular and triangular loads as follows: The maximum load on the spoil heap is calculated as shown in equation (1): P=γ t H t (1) In the formula: γ t Unit weight of fill material for spoil heap; H t The height of the spoil heap; Based on the Businsk solution, the additional load σ generated by the slope fill at the bottom of the slope is calculated as a triangular load. z1 As shown in equation (2): Based on the Businskews solution principle, the additional load σ generated by the fill material at the bottom of the slope after dividing the rectangular load at the top of the slope is calculated. z2 As shown in equation (3): In equations (2) and (3): b is the length from the bottom of the slope to the top of the slope; l is the length from the origin of the slope bottom direction to the boundary of the spoil heap; γ t Unit weight of fill material for spoil heap; H t The height of the spoil heap is represented by x, y, and z; x, y, and z represent the spatial location of the fill material; the origin of the coordinate system is located at the midpoint of the slope baseline, the x-direction is perpendicular to the slope baseline through the origin, the y-direction is parallel to the slope baseline through the origin, and the z-direction is the depth below the midpoint of the slope baseline. At this time, the total additional load σ generated by the spoil heap in the slope toe area is... z As shown in equation (4): s z =s z1 +s z2 (4) Calculate the self-weight load σ of the soil and rock layer at the slope toe. cz As shown in equation (5): In the formula: n is the number of soil and rock layers above the calculation depth; γ i To calculate the unit weight of the soil and rock layers above the depth, the buoyant unit weight of the permeable layer below the groundwater level is used; h i To calculate the thickness of each soil layer above the depth; At this point, the total load P on the foundation soil layer at the toe of the slope is as shown in equation (6): P=σ z +s cz (6) 4. The method for determining the bearing capacity of a spoil heap foundation based on the Bussinisk solution according to claim 1, characterized in that, In S3, the correction formula for depth correction based on the thickness of each soil layer is shown in equation (7): In the formula: f aki These are the characteristic values ​​of the bearing capacity of each soil layer below the foundation. η i γ is the correction factor for the bearing capacity of each soil layer below the foundation; i To calculate the unit weight of the soil and rock layers above the depth, the buoyant unit weight of the permeable layer below the groundwater level is used; h i To calculate the thickness of each soil layer above the depth.

5. The method for determining the bearing capacity of a spoil heap foundation based on the Bussinisk solution according to claim 1, characterized in that, In S4, the additional load and bearing capacity at various depths below the foundation are compared, as shown in Equation (8): f a ≥K×P(8) In the formula: f a denoted as ρ, where ρ is the soil bearing capacity; K is the foundation bearing capacity safety factor; and P is the total load on the soil and rock layer at the slope toe.

6. The method for determining the bearing capacity of a spoil heap foundation based on the Businskew solution according to claim 1, characterized in that, In S4, the determination and adjustment of the foundation bearing capacity safety factor are as follows: When the bearing capacity requirement shown in Equation (8) is met at different depths of the foundation, the bearing capacity of the spoil heap foundation meets the requirements; When the bearing capacity requirements shown in Equation (8) are not met at different depths of the foundation, the range of soil layers to be treated and the required increase in the bearing capacity of each soil layer are determined by adjusting the characteristic values ​​of the bearing capacity of each soil layer until the conditions of Equation (8) are met.

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