Soft soil foundation road construction method

Abstract

The invention relates to a soft soil foundation road construction method which comprises the following steps: determining a first drainage depth and a second drainage depth, and enabling the second drainage depth to be smaller than the first drainage depth; a first drainage ditch is dug in one side of the road to be constructed according to the first drainage depth; excavating a second drainage ditch on the other side of the road to be constructed according to the second drainage depth; determining the thickness of a to-be-replaced fill stratum, wherein the thickness of the to-be-replaced fill stratum is smaller than the first drainage depth; after drainage is completed, upper-layer soil is dug out according to the thickness of the to-be-replaced filling layer, and lime soil with the same thickness is replaced and filled; and after the foundation bearing capacity is verified to be qualified, a concrete surface layer is poured, and road construction is completed. The soft soil foundation road construction method solves the problem that an existing soft soil foundation treatment method cannot give consideration to the treatment cost and the construction period when the thickness of a soft soil layer is large.

Description

Technical Field

[0001] The present invention relates to the technical field of road construction, in particular to a soft soil foundation road construction method. Background Art

[0002] Before road construction, the foundation needs to be treated. Currently, the soil replacement cushion method is generally used to treat soft soil foundations. This method involves excavating soft soil layers such as silt and miscellaneous fill and replacing them with well-graded 7:3 sand and gravel or crushed stone soil. Its characteristics are: simple construction process, short construction period, good economy, and it is suitable for shallow soft soil treatment. However, when the thickness of the soft soil layer reaches 3m or more, the cost of excavation and transportation of earthwork increases significantly. If the replacement depth is reduced for economic reasons, the soft soil foundation will settle after road construction is completed, causing ground cracking and high subsequent maintenance costs. If the drainage consolidation method is used to treat the soft soil foundation, the construction period can be as long as 3-6 months, which is too long. Summary of the Invention

[0003] The main purpose of the present invention is to propose a soft soil foundation road construction method, which aims to solve the problem that the existing soft soil foundation treatment method cannot take into account both treatment cost and construction period when the soft soil layer is thick.

[0004] To achieve the above object, the present invention proposes a soft soil foundation road construction method, comprising the following steps:

[0005] determining a first drainage depth and a second drainage depth, wherein the second drainage depth is smaller than the first drainage depth;

[0006] excavating a first drainage ditch on one side of the road to be constructed according to the first drainage depth;

[0007] excavating a second drainage ditch on the other side of the road to be constructed according to the second drainage depth;

[0008] Determining a thickness of a soil layer to be replaced, wherein the thickness of the soil layer to be replaced is less than the first drainage depth;

[0009] After the drainage is completed, the upper soil layer is excavated according to the thickness of the soil layer to be replaced and replaced with lime soil of the same thickness;

[0010] After the foundation bearing capacity is verified to be qualified, the concrete surface layer is poured to complete the road construction.

[0011] According to some embodiments of the present invention, determining the first drainage depth and the second drainage depth includes:

[0012] Obtain the depth of the soft soil foundation to be treated;

[0013] Determining the first drainage depth according to the depth of the soft soil foundation to be treated;

[0014] Obtain the designed daily drainage volume and the width of the road to be constructed;

[0015] The second drainage depth is determined according to the first drainage depth, the designed daily drainage volume and the road width.

[0016] According to some embodiments of the present invention, determining the second drainage depth according to the first drainage depth, the designed daily drainage volume, and the road width includes:

[0017] Calculating a water-passing cross-sectional area according to the first drainage depth and the road width;

[0018] Get the horizontal permeability coefficient of soft soil;

[0019] Calculating the hydraulic gradient based on the designed daily discharge volume, the water flow cross-sectional area, and the horizontal permeability coefficient of the soft soil;

[0020] The second drainage depth is calculated according to the hydraulic gradient, the first drainage depth and the road width.

[0021] According to some embodiments of the present invention, determining the thickness of the soil layer to be replaced includes:

[0022] Determine the height difference between the soft soil layer to be consolidated and the designed road;

[0023] Obtain soft soil settlement;

[0024] The thickness of the soil layer to be replaced is calculated based on the height difference and the soft soil settlement.

[0025] According to some embodiments of the present invention, determining the height difference between the soft soil layer to be consolidated and the designed road includes:

[0026] Obtain the design soft soil consolidation time and consolidation time factor;

[0027] Determine the correction factor for rolling depth and consolidation coefficient;

[0028] The height difference is calculated based on the designed soft soil consolidation time, the consolidation time factor, the rolling influence depth correction coefficient and the consolidation coefficient.

[0029] According to some embodiments of the present invention, determining the compaction impact depth correction coefficient and the consolidation coefficient includes:

[0030] Obtain rolling dynamic load and soil pre-consolidation pressure;

[0031] Calculating the rolling impact depth correction coefficient according to the rolling dynamic load and the soil pre-consolidation pressure;

[0032] Obtain vertical permeability coefficient of soft soil;

[0033] Calculating an equivalent vertical permeability coefficient based on the rolling impact depth correction coefficient and the soft soil vertical permeability coefficient;

[0034] Obtain the initial void ratio, soft soil compressibility and water density;

[0035] The consolidation coefficient is calculated according to the equivalent vertical permeability coefficient, the initial porosity, the soft soil compression coefficient and the bulk density.

[0036] According to some embodiments of the present invention, after excavating a first drainage ditch on one side of the road to be constructed according to the first drainage depth, the method further includes:

[0037] A plurality of drainage holes are arranged at intervals in the vertical direction on the ditch wall on one side of the first drainage ditch facing the road to be constructed, so that the projections of the drainage holes in the vertical direction are staggered.

[0038] According to some embodiments of the present invention, the excavating of the upper soil layer and replacing it with lime soil of the same thickness according to the thickness of the soil layer to be replaced includes:

[0039] Excavate the upper soil layer according to the thickness of the soil layer to be replaced;

[0040] The clay excavated on site is mixed with lime in a ratio of 8 to 2 to form lime soil;

[0041] Divide the ash soil into multiple layers, each layer having a thickness of 25-30 cm;

[0042] After each layer of ash soil is replaced, it is rolled and compacted multiple times until the measured compaction coefficient is greater than the designed compaction coefficient, and the total thickness of the compacted ash soil layer is consistent with the thickness of the excavated upper soil layer.

[0043] According to some embodiments of the present invention, after removing the upper soil layer according to the thickness of the soil layer to be replaced and replacing it with lime soil of the same thickness, the method further includes:

[0044] Lay 30cm thick cement-stabilized gravel with a cement content of 3% to 5%, and add water to the cement-stabilized gravel;

[0045] After the moisture content of the cement-stabilized gravel layer reaches the designed moisture content, the cement-stabilized gravel layer is rolled until the compaction degree of the cement-stabilized gravel layer is greater than the designed compaction degree.

[0046] According to some embodiments of the present invention, the pouring of the concrete surface layer includes:

[0047] Concrete surface layers are poured from the middle of the road to both sides, so that the middle of the road is tilted downward toward the direction close to each drainage ditch, with an inclination angle of 1.5°.

[0048] The present invention has at least the following beneficial effects:

[0049] In the present invention, the soft soil foundation road construction method includes the following steps: determining a first drainage depth and a second drainage depth, with the second drainage depth being less than the first drainage depth; excavating a first drainage ditch on one side of the road to be constructed according to the first drainage depth; excavating a second drainage ditch on the other side of the road to be constructed according to the second drainage depth; determining the thickness of the soil layer to be replaced, with the thickness of the soil layer to be replaced being less than the first drainage depth; after drainage is completed, excavating the upper soil layer according to the thickness of the soil layer to be replaced and replacing it with lime soil of the same thickness; after the foundation bearing capacity is verified to be qualified, pouring the concrete surface layer to complete the road construction. By excavating two drainage ditches of different depths on both sides of the road to be constructed, the present invention increases the hydraulic gradient, accelerates horizontal drainage, and shortens the construction period. Subsequently, after drainage is completed, a portion of the upper soil layer is excavated and replaced with lime soil of the same thickness. This eliminates the need to wait for the entire soil layer to consolidate naturally as in the traditional drainage consolidation method, further shortening the construction period. Replacing a portion of the upper soil layer significantly reduces construction costs compared to the traditional soil replacement cushion method, which completely replaces the soft soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0051] Figure 1 This is a schematic flow chart of a first embodiment of a soft soil foundation road construction method according to the present invention;

[0052] Figure 2 This is a schematic flow chart of a second embodiment of the soft soil foundation road construction method of the present invention;

[0053] Figure 3 This is a schematic flow chart of a third embodiment of a soft soil foundation road construction method according to the present invention;

[0054] Figure 4 This is a schematic flow chart of a fourth embodiment of a soft soil foundation road construction method according to the present invention;

[0055] Figure 5 This is a schematic flow chart of a fifth embodiment of the soft soil foundation road construction method of the present invention;

[0056] Figure 6 This is a schematic flow chart of a sixth embodiment of the soft soil foundation road construction method of the present invention;

[0057] Figure 7 This is a schematic flow chart of a seventh embodiment of the soft soil foundation road construction method of the present invention;

[0058] Figure 8 This is a schematic flow chart of an eighth embodiment of the soft soil foundation road construction method of the present invention;

[0059] Figure 9 This is a schematic flow chart of a ninth embodiment of the soft soil foundation road construction method of the present invention;

[0060] Figure 10 This is a schematic flow chart of a tenth embodiment of a soft soil foundation road construction method according to the present invention;

[0061] Figure 11 A schematic diagram of excavating a first drainage ditch and a second drainage ditch for a soft soil foundation road according to the present invention;

[0062] Figure 12 This is a schematic diagram of a soft soil foundation road after replacing the lime soil of the present invention;

[0063] Figure 13 This is a schematic diagram of the soft soil foundation road after construction of the present invention is completed.

[0064] Description of reference numerals:

[0065] 100-soft soil foundation road; 1-first drainage ditch; 11-scupper hole; 2-second drainage ditch; 3-lime soil layer; 4-concrete surface layer; 5-cement-stabilized gravel layer; 6-soft soil layer. DETAILED DESCRIPTION

[0066] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0067] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0068] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0069] The present invention provides a soft soil foundation road construction method. Figures 1 to 13 This is a specific embodiment of a soft soil foundation road construction method provided by the present invention.

[0070] like Figure 1 As shown, an embodiment of the present invention provides a soft soil foundation road construction method, comprising the following steps:

[0071] Step S10: determining a first drainage depth and a second drainage depth, and making the second drainage depth smaller than the first drainage depth.

[0072] Step S20: excavating a first drainage ditch 1 on one side of the road to be constructed according to the first drainage depth.

[0073] Step S40: excavating a second drainage ditch 2 on the other side of the road to be constructed according to the second drainage depth.

[0074] It should be noted that if Figure 11 As shown, since the second drainage depth is less than the first drainage depth, according to Darcy's law, water always flows from the high head area to the low head area, and the first drainage ditch 1 is deeper than the second drainage ditch 2. The first drainage ditch 1 is a low head area, so most of the water in the soft soil foundation is discharged to the first drainage ditch 1.

[0075] It should be noted that the greater the depth difference between the first drainage ditch 1 and the second drainage ditch 2, the greater the hydraulic gradient and the higher the drainage efficiency in the horizontal direction. Theoretically, when the second drainage depth approaches 0, the drainage efficiency is the highest. However, in order to avoid the other side of the road to be constructed becoming an open boundary, causing groundwater to bypass or diffuse laterally, thereby reducing the drainage efficiency, the second drainage ditch 2 needs to always be lower than the road to be constructed to maintain the closure of the drainage system. Therefore, the second drainage depth needs to be greater than the soft soil settlement after drainage.

[0076] Step S50: determining the thickness of the soil layer to be replaced, where the thickness of the soil layer to be replaced is less than the first drainage depth.

[0077] It should be noted that if Figure 12 As shown, the present invention excavates part of the upper soil and replaces it with gray soil of the same thickness. There is no need to wait for all the soil layers to consolidate naturally like the traditional drainage consolidation method, which shortens the construction period. Compared with the traditional soil replacement cushion method of replacing all the soft soil, replacing part of the upper soil greatly reduces the construction cost. Therefore, the thickness of the soil layer to be replaced is less than the first drainage depth.

[0078] Step S60: After the drainage is completed, the upper layer of soil is excavated according to the thickness of the soil layer to be replaced and replaced with gray soil of the same thickness.

[0079] It should be noted that the thickness of the removed upper soil layer and the thickness of the lime soil layer 3 after replacement are both consistent with the thickness of the soil layer to be replaced.

[0080] Step S90: After the foundation bearing capacity is verified to be qualified, pour the concrete surface layer 4 to complete the road construction.

[0081] It should be noted that when the measured foundation bearing capacity is greater than 150kPa, it means that the foundation bearing capacity is qualified.

[0082] It should be noted that after the road construction is completed, the first drainage ditch 1 and the second drainage ditch 2 need to be backfilled, and drainage facilities need to be installed on both sides of the road.

[0083] In the present invention, the soft soil foundation road construction method includes the following steps: determining a first drainage depth and a second drainage depth, with the second drainage depth being less than the first drainage depth; excavating a first drainage ditch 1 on one side of the road to be constructed according to the first drainage depth; excavating a second drainage ditch 2 on the other side of the road to be constructed according to the second drainage depth; determining the thickness of the soil layer to be replaced, with the thickness of the soil layer to be replaced being less than the first drainage depth; after drainage is completed, excavating the upper soil layer according to the thickness of the soil layer to be replaced and replacing it with lime soil of equal thickness; and after the foundation bearing capacity is verified to be qualified, pouring a concrete surface layer 4 to complete the road construction. By excavating two drainage ditches of different depths on both sides of the road to be constructed, the present invention increases the hydraulic gradient, accelerates horizontal drainage, and shortens the construction period. Subsequently, after drainage is completed, a portion of the upper soil layer is excavated and replaced with lime soil of equal thickness. This eliminates the need to wait for the entire soil layer to naturally consolidate as in the traditional drainage consolidation method, further shortening the construction period. Replacing a portion of the upper soil layer significantly reduces construction costs compared to the traditional soil replacement cushion method, which replaces the entire soft soil layer.

[0084] refer to Figure 2 , Figure 2 Schematic diagram of the process of the second embodiment of the soft soil foundation road construction method of the present invention.

[0085] Based on the first embodiment described above, the soft soil foundation road construction method of this embodiment includes, in step S10:

[0086] Step S11: Obtain the depth of the soft soil foundation to be processed.

[0087] It should be noted that construction workers can detect the depth of the soft soil foundation on site.

[0088] Step S12: determining the first drainage depth according to the depth of the soft soil foundation to be processed.

[0089] It should be noted that the first drainage depth is equal to the depth of the soft soil foundation to be treated.

[0090] Step S13: Obtain the designed daily drainage volume and the width of the road to be constructed.

[0091] It should be noted that the designed daily drainage volume is determined according to the designed construction period. After the total water volume is calculated, the daily drainage task is allocated according to the period used for drainage in the designed construction period. The width of the road to be constructed can be obtained by on-site inspection by construction personnel.

[0092] Step S14: determining the second drainage depth according to the first drainage depth, the designed daily drainage volume, and the road width.

[0093] In this embodiment, the depth of the soft soil foundation to be treated is first obtained, then the first drainage depth is determined based on the depth of the soft soil foundation to be treated, then the designed daily drainage volume and the width of the road to be constructed are obtained, and finally the second drainage depth is determined based on the first drainage depth, the designed daily drainage volume and the road width.

[0094] refer to Figure 3 , Figure 3 1 is a flow chart of a third embodiment of a soft soil foundation road construction method according to the present invention.

[0095] Based on the above second embodiment, the soft soil foundation road construction method of this embodiment includes, in step S14:

[0096] Step S141: Calculating a water-passing cross-sectional area according to the first drainage depth and the road width.

[0097] It should be noted that the cross-sectional area of ​​water flow is set to A, the first drainage depth is set to H0, and the road width is set to L. The formula for calculating the cross-sectional area of ​​water flow is: .

[0098] Step S142: Obtain the horizontal permeability coefficient of soft soil.

[0099] It should be noted that the horizontal permeability coefficient of soft soil can be obtained by looking up the table. In this embodiment, the horizontal permeability coefficient of soft soil is =7×10 -6 cm / s.

[0100] Step S143: Calculate the hydraulic gradient based on the designed daily discharge volume, the water flow cross-sectional area, and the soft soil horizontal permeability coefficient.

[0101] It should be noted that the designed daily discharge is set as Q, and the hydraulic gradient is set as i. According to Darcy's law, it can be known that: , the hydraulic gradient value can be calculated by substituting the designed daily discharge volume, the water-passing cross-sectional area and the soft soil horizontal permeability coefficient into the formula.

[0102] Step S144: Calculating the second drainage depth according to the hydraulic gradient, the first drainage depth, and the road width.

[0103] It should be noted that the second drainage depth is set to H1, and the hydraulic gradient formula is: , the second drainage depth can be calculated by substituting the hydraulic gradient, the first drainage depth and the road width into the formula.

[0104] In this embodiment, the water-passing cross-sectional area is first calculated based on the first drainage depth and the road width, and then the soft soil horizontal permeability coefficient is obtained. Then, the hydraulic gradient is calculated based on the designed daily drainage volume, the water-passing cross-sectional area, and the soft soil horizontal permeability coefficient. Finally, the second drainage depth is calculated based on the hydraulic gradient, the first drainage depth, and the road width.

[0105] refer to Figure 4 , Figure 4 1 is a flow chart of a fourth embodiment of a soft soil foundation road construction method according to the present invention.

[0106] Based on the first embodiment described above, the soft soil foundation road construction method of this embodiment includes, in step S50:

[0107] Step S51: Determine the height difference between the soft soil layer 6 to be consolidated and the designed road.

[0108] It should be noted that, since the lower soft soil in this application adopts the drainage consolidation method and the upper soft soil adopts the replacement method, the height difference between the soft soil layer 6 to be consolidated and the designed road is the height difference between the lower soft soil surface after settlement and the designed road surface.

[0109] Step S52: Obtain soft soil settlement.

[0110] It should be noted that the soft soil settlement can be obtained by actual measurement by construction personnel after drainage is completed.

[0111] Step S53: Calculating the thickness of the soil layer to be replaced based on the height difference and the soft soil settlement.

[0112] It should be noted that the thickness of the soil layer to be replaced is the value of the height difference minus the soft soil settlement.

[0113] In this embodiment, the height difference between the soft soil layer 6 to be consolidated and the designed road is first determined, and then the construction personnel measure the soft soil settlement after drainage is completed. Finally, the thickness of the soil layer to be replaced is calculated based on the height difference and the soft soil settlement.

[0114] refer to Figure 5 , Figure 5 1 is a flow chart of a fifth embodiment of a soft soil foundation road construction method according to the present invention.

[0115] Based on the fourth embodiment, the soft soil foundation road construction method of this embodiment includes, in step S51:

[0116] Step S511: Obtain the designed soft soil consolidation time and consolidation time factor.

[0117] It should be noted that the designed soft soil consolidation time is the time required to reach 90% consolidation degree, which can be determined according to the designed construction period, and the fixed time factor can be obtained by looking up the table.

[0118] Step S512: Determine the rolling impact depth correction coefficient and consolidation coefficient.

[0119] Step S513: Calculating the height difference according to the designed soft soil consolidation time, the consolidation time factor, the rolling influence depth correction coefficient and the consolidation coefficient.

[0120] It should be noted that the designed soft soil consolidation time is set as t 90 , the fixed time factor is set to , the rolling depth correction coefficient is set to β, and the consolidation coefficient is set to , the height difference is set to H, and the consolidation time calculation formula is: , the height difference can be calculated by substituting the designed soft soil consolidation time, the consolidation time factor, the rolling influence depth correction coefficient and the consolidation coefficient into the formula.

[0121] In this embodiment, the designed soft soil consolidation time and the consolidation time factor are first obtained, then the rolling influence depth correction coefficient and the consolidation coefficient are determined, and finally the height difference is calculated based on the designed soft soil consolidation time, the consolidation time factor, the rolling influence depth correction coefficient and the consolidation coefficient.

[0122] refer to Figure 6 , Figure 6 1 is a flow chart of a sixth embodiment of a soft soil foundation road construction method according to the present invention.

[0123] Based on the fifth embodiment, the soft soil foundation road construction method of this embodiment includes, in step S512:

[0124] Step S5121: Obtain the dynamic rolling load and the preliminary consolidation pressure of the soil.

[0125] It should be noted that the specific value of the dynamic rolling load is determined by the on-site rolling equipment, and the preliminary consolidation pressure of the soil can be measured through consolidation experiments.

[0126] Step S5122: Calculate the rolling influence depth correction coefficient based on the rolling dynamic load and the soil prior consolidation pressure.

[0127] It should be noted that the rolling dynamic load is set to q, and the soil pre-consolidation pressure is set to , the rolling depth correction coefficient formula is: By substituting the rolling dynamic load and the soil pre-consolidation pressure into the formula, the rolling influence depth correction coefficient can be calculated.

[0128] Step S5123: Obtain the vertical permeability coefficient of soft soil.

[0129] It should be noted that the vertical permeability coefficient of soft soil can be obtained by looking up the table. In this embodiment, the vertical permeability coefficient of soft soil is =5×10 -6 cm / s.

[0130] Step S5124: Calculate the equivalent vertical permeability coefficient based on the rolling influence depth correction coefficient and the soft soil vertical permeability coefficient.

[0131] It should be noted that, since the rolling of the roller can accelerate the discharge of water in the vertical direction, the equivalent vertical permeability coefficient is greater than the soft soil vertical permeability coefficient.

[0132] It should be noted that the equivalent vertical permeability coefficient is set to , the calculation formula of the equivalent vertical permeability is: , the equivalent vertical permeability coefficient can be calculated by substituting the rolling influence depth correction coefficient and the soft soil vertical permeability coefficient into the formula.

[0133] Step S5125: Obtain the initial void ratio, soft soil compressibility, and water density.

[0134] It should be noted that the initial porosity of the soft soil can be obtained through geotechnical experiments, the compression coefficient of the soft soil can be measured through consolidation experiments, and the bulk density of water can be obtained by looking up the table.

[0135] Step S5126: Calculate the consolidation coefficient according to the equivalent vertical permeability coefficient, the initial porosity ratio, the soft soil compression coefficient and the bulk density.

[0136] It should be noted that the initial porosity ratio is set to , the soft soil compression coefficient is set to , the specific gravity of water is set to , the calculation formula of the consolidation coefficient is: The consolidation coefficient can be calculated by substituting the equivalent vertical permeability coefficient, the initial porosity, the soft soil compression coefficient and the bulk density into the formula.

[0137] In this embodiment, the dynamic load of rolling and the initial consolidation pressure of the soil are first obtained, and then the rolling influence depth correction coefficient is calculated based on the dynamic load of rolling and the initial consolidation pressure of the soil. Then, the vertical permeability coefficient of soft soil is obtained, and the equivalent vertical permeability coefficient is calculated based on the rolling influence depth correction coefficient and the vertical permeability coefficient of soft soil. Finally, the initial porosity, soft soil compression coefficient and water bulk density are obtained, and the consolidation coefficient is calculated based on the equivalent vertical permeability coefficient, the initial porosity, the soft soil compression coefficient and the bulk density.

[0138] refer to Figure 7 , Figure 7 1 is a flow chart of the seventh embodiment of the soft soil foundation road construction method of the present invention.

[0139] Based on the first embodiment described above, the soft soil foundation road construction method of this embodiment further includes, after step S20:

[0140] Step S30: a plurality of drainage holes 11 are provided at intervals in the vertical direction on the ditch wall of the first drainage ditch 1 facing the road to be constructed, so that the projections of the drainage holes 11 in the vertical direction are staggered.

[0141] It should be noted that by opening the drainage holes 11, the water in the soft soil can be guided to drain into the first drainage ditch 1, thereby accelerating drainage, and the projections of each drainage hole 11 in the vertical direction are staggered. On the one hand, it can improve the drainage uniformity and reduce the hydraulic erosion of the local area of ​​the first drainage ditch 1. On the other hand, it can enhance the anti-blocking performance.

[0142] In this embodiment, after the first drainage ditch 1 is dug, a plurality of drainage holes 11 are provided at intervals in the vertical direction on the ditch wall of the first drainage ditch 1 facing the road to be constructed, so that the projections of each drainage hole 11 in the vertical direction are staggered. On the one hand, this can improve the drainage uniformity and reduce hydraulic erosion in the local area of ​​the first drainage ditch 1; on the other hand, it can enhance the anti-blocking performance.

[0143] refer to Figure 8 , Figure 8 1 is a flow chart of an eighth embodiment of a soft soil foundation road construction method according to the present invention.

[0144] Based on the first embodiment described above, the soft soil foundation road construction method of this embodiment includes, in step S60:

[0145] Step S61: excavating the upper soil layer according to the thickness of the soil layer to be replaced.

[0146] Step S62: Clay excavated on site is mixed with lime in a ratio of 8 to 2 to form lime soil.

[0147] It should be noted that directly utilizing the clay excavated on site saves material and transportation costs.

[0148] Specifically, the ratio of lime to clay is 2:8. Clay hardens after mixing with lime, which can improve the bearing capacity of the foundation after replacement.

[0149] Step S63: Divide the ash soil into multiple layers, with each layer of ash soil having a thickness of 25-30 cm.

[0150] It should be noted that the thickness of each layer of ash soil is set to 25-30cm to facilitate compaction by roller equipment.

[0151] Step S64: After each layer of ash soil is replaced, it is rolled and compacted multiple times until the measured compaction coefficient is greater than the designed compaction coefficient, and the total thickness of the compacted ash soil layer 3 is consistent with the thickness of the excavated upper soil layer.

[0152] It should be noted that through layered compaction, the time that the ash soil is exposed to the air can be extended, and the lime hardening reaction can be accelerated. At the same time, multiple rolling and tamping are carried out through roller equipment. On the one hand, the super-pore water is stimulated by pressure, and the rolling load increases the permeability gradient of the soil. On the other hand, the rolling cracks form vertical preferential flow paths, which improves the vertical drainage efficiency.

[0153] Specifically, the designed compaction coefficient is 0.93. When the measured compaction coefficient is ≥ 0.93, it indicates that the compaction effect meets the requirements.

[0154] In this embodiment, the upper soil layer is first excavated according to the thickness of the soil layer to be replaced, and the clay excavated on site is mixed with lime in a ratio of 8 to 2 to form ash soil. Then the ash soil is divided into multiple layers, and the thickness of each layer of ash soil is 25-30 cm. After each layer of ash soil is replaced, it is rolled and compacted multiple times until the measured compaction coefficient is greater than the designed compaction coefficient, and the total thickness of the compacted ash soil layer 3 is consistent with the thickness of the excavated upper soil layer.

[0155] refer to Figure 9 , Figure 9 2 is a flow chart of a ninth embodiment of a soft soil foundation road construction method according to the present invention.

[0156] Based on the eighth embodiment, the soft soil foundation road construction method of this embodiment further includes, after step S60:

[0157] Step S70: Lay cement-stabilized gravel with a cement content of 3% to 5% and a thickness of 30 cm, and add water to the cement-stabilized gravel.

[0158] It should be noted that since the elastic modulus of cement-stabilized gravel is significantly higher than that of lime soil, laying cement-stabilized gravel on the lime soil layer 3 can evenly distribute the vehicle load stress on the road, avoiding stress concentration that causes road cracking. At the same time, a cement content of 3% to 5% is in the optimal strength range. A content below 3% will result in insufficient strength, and a content above 5% will increase the risk of shrinkage cracking.

[0159] Step S80: After the water content of the cement-stabilized gravel layer 5 reaches the designed water content, the cement-stabilized gravel layer 5 is rolled until the compaction degree of the cement-stabilized gravel layer 5 is greater than the designed compaction degree.

[0160] It should be noted that rolling the cement-stabilized gravel layer 5 when the water content of the cement-stabilized gravel layer 5 is slightly greater than the designed water content can reduce the flatness deviation after compaction and provide an accurate benchmark for the concrete surface layer 4.

[0161] It should be noted that the designed compaction degree is 97%. The dense structure with a compaction degree of ≥97% makes the permeability coefficient <10 - 7 cm / s, effectively preventing groundwater from rising along the capillary and softening the gray soil layer.

[0162] In this embodiment, if Figure 13 As shown, after replacing the ash soil, a 30 cm thick cement-stabilized gravel with a cement content of 3% to 5% is laid, and water is added to the cement-stabilized gravel. Then, after the water content of the cement-stabilized gravel layer 5 reaches the designed water content, the cement-stabilized gravel layer 5 is rolled until the compaction degree of the cement-stabilized gravel layer 5 is greater than the designed compaction degree.

[0163] refer to Figure 10 , Figure 10 1 is a flow chart of the tenth embodiment of the soft soil foundation road construction method of the present invention.

[0164] Based on the first embodiment described above, the soft soil foundation road construction method of this embodiment includes, in step S90:

[0165] Step S91: pouring concrete surface layers 4 from the middle of the road to both sides, so that the middle of the road is tilted downward toward the direction close to each drainage ditch, with an inclination angle of 1.5°.

[0166] It should be noted that if Figure 13 As shown, the road is tilted from the middle to both sides. On the one hand, it allows rainwater on the road to be discharged from both sides along the slope. On the other hand, since the soft soil foundation is prone to lateral displacement under load, the inclined design causes the road's own weight to generate a component force toward the ditch side, balancing the side pressure of the soil and reducing the risk of shoulder cracking.

[0167] In this embodiment, after the foundation bearing capacity is verified to be qualified, the concrete surface layer 4 is poured from the middle of the road to both sides, so that the middle of the road is tilted downward toward the direction close to each drainage ditch, with an inclination angle of 1.5° to complete the road construction.

[0168] It should be understood that, although the various steps in the flowchart in the embodiment of the present application are shown in sequence according to the indication of the arrows, these steps are not necessarily performed in sequence in the order indicated by the arrows. Unless clearly stated herein, the execution of these steps is not strictly limited in order, and they can be performed in other orders. Moreover, at least a portion of the steps in the figure may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily performed at the same time, but can be performed at different times, and their execution order is not necessarily performed in sequence, but can be performed in turn or alternately with at least a portion of other steps or sub-steps or stages of other steps.

[0169] It should be understood that the above is only an example and does not constitute any limitation to the technical solution of the present invention. In specific applications, those skilled in the art can make settings as needed, and the present invention does not impose any limitation on this.

[0170] It should be noted that the workflow described above is merely illustrative and does not limit the scope of protection of the present invention. In practical applications, technicians in this field can select part or all of it according to actual needs to achieve the purpose of the embodiment scheme, and no limitation is made here.

[0171] In addition, it should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or system comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or system. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or system comprising the element.

[0172] The serial numbers of the above embodiments of the present invention are for description only and do not represent the advantages or disadvantages of the embodiments.

[0173] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A soft soil foundation road construction method, characterized in that: The following steps are involved: determining a first drainage depth and a second drainage depth, wherein the second drainage depth is smaller than the first drainage depth; excavating a first drainage ditch on one side of the road to be constructed according to the first drainage depth; excavating a second drainage ditch on the other side of the road to be constructed according to the second drainage depth; Determining a thickness of a soil layer to be replaced, wherein the thickness of the soil layer to be replaced is less than the first drainage depth; After the drainage is completed, the upper soil layer is excavated according to the thickness of the soil layer to be replaced and replaced with lime soil of the same thickness; After the foundation bearing capacity is verified to be qualified, the concrete surface layer is poured to complete the road construction.

2. The soft soil foundation road construction method according to claim 1, characterized in that: The determining of the first drainage depth and the second drainage depth comprises: Obtain the depth of the soft soil foundation to be treated; Determining the first drainage depth according to the depth of the soft soil foundation to be treated; Obtain the designed daily drainage volume and the width of the road to be constructed; The second drainage depth is determined according to the first drainage depth, the designed daily drainage volume and the road width.

3. The soft soil foundation road construction method according to claim 2, characterized in that: The determining the second drainage depth according to the first drainage depth, the designed daily drainage volume, and the road width includes: Calculating a water-passing cross-sectional area according to the first drainage depth and the road width; Get the horizontal permeability coefficient of soft soil; Calculating the hydraulic gradient based on the designed daily discharge volume, the water flow cross-sectional area, and the horizontal permeability coefficient of the soft soil; The second drainage depth is calculated according to the hydraulic gradient, the first drainage depth and the road width.

4. The soft soil foundation road construction method according to claim 1, characterized in that: Determining the thickness of the soil layer to be replaced includes: Determine the height difference between the soft soil layer to be consolidated and the designed road; Obtain soft soil settlement; The thickness of the soil layer to be replaced is calculated based on the height difference and the soft soil settlement.

5. The soft soil foundation road construction method according to claim 4, characterized in that: Determining the height difference between the soft soil layer to be consolidated and the designed road includes: Obtain the design soft soil consolidation time and consolidation time factor; Determine the correction factor for rolling depth and consolidation coefficient; The height difference is calculated based on the designed soft soil consolidation time, the consolidation time factor, the rolling influence depth correction coefficient and the consolidation coefficient.

6. The soft soil foundation road construction method according to claim 5, characterized in that: The determination of the rolling impact depth correction coefficient and the consolidation coefficient includes: Obtain rolling dynamic load and soil pre-consolidation pressure; Calculating the rolling impact depth correction coefficient according to the rolling dynamic load and the soil pre-consolidation pressure; Obtain vertical permeability coefficient of soft soil; Calculating an equivalent vertical permeability coefficient based on the rolling impact depth correction coefficient and the soft soil vertical permeability coefficient; Obtain the initial void ratio, soft soil compressibility and water density; The consolidation coefficient is calculated according to the equivalent vertical permeability coefficient, the initial porosity, the soft soil compression coefficient and the bulk density.

7. The soft soil foundation road construction method according to claim 1, characterized in that: After excavating a first drainage ditch on one side of the road to be constructed according to the first drainage depth, the method further includes: A plurality of drainage holes are arranged at intervals in the vertical direction on the ditch wall on one side of the first drainage ditch facing the road to be constructed, so that the projections of the drainage holes in the vertical direction are staggered.

8. The soft soil foundation road construction method according to claim 1, characterized in that: The method of excavating the upper soil layer according to the thickness of the soil layer to be replaced and replacing it with lime soil of the same thickness includes: Excavate the upper soil layer according to the thickness of the soil layer to be replaced; The clay excavated on site is mixed with lime in a ratio of 8 to 2 to form lime soil; Divide the ash soil into multiple layers, each layer having a thickness of 25-30 cm; After each layer of ash soil is replaced, it is rolled and compacted multiple times until the measured compaction coefficient is greater than the designed compaction coefficient, and the total thickness of the compacted ash soil layer is consistent with the thickness of the excavated upper soil layer.

9. The soft soil foundation road construction method according to claim 1, characterized in that: After excavating the upper soil layer according to the thickness of the soil layer to be replaced and replacing it with lime soil of the same thickness, the method further includes: Lay 30cm thick cement-stabilized gravel with a cement content of 3% to 5%, and add water to the cement-stabilized gravel; After the moisture content of the cement-stabilized gravel layer reaches the designed moisture content, the cement-stabilized gravel layer is rolled until the compaction degree of the cement-stabilized gravel layer is greater than the designed compaction degree.

10. The soft soil foundation road construction method according to claim 1, characterized in that: The pouring concrete surface layer comprises: Concrete surface layers are poured from the middle of the road to both sides, so that the middle of the road is tilted downward toward the direction close to each drainage ditch, with an inclination angle of 1.5°.

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