Novel structure for treating roadbed landslide by using reinforced modified soil and construction method of novel structure

Abstract

The invention belongs to the technical field of road slope engineering, and particularly relates to a novel structure for treating roadbed landslide through reinforced modified soil and a construction method of the novel structure. The novel structure is formed by retreating a side slope where a landslide happens, the novel structure conducts modification treatment on a side slope soil body, and in the side slope reconstruction process, a grating reinforcement layer and a blind ditch structure are arranged, so that the novel structure forms a semi-flexible and semi-rigid protection structure, the overall strength and drainage performance of the novel structure are improved, and the service life of the novel structure is prolonged. And therefore, the novel structure has better stability, the construction cost is lower, the economical efficiency is better, and the environmental benefit is obvious. The topmost layer and the bottommost layer are provided with the top waterproof layer and the bottom waterproof layer correspondingly, falling rain and underground water can be prevented from permeating into the new structure, the blind ditches are arranged between the top waterproof layer and the bottom waterproof layer, water in the new landslide structure can be well drained through the blind ditches, and the situation that the interior of a slope is in a high-water-content state for a long time is avoided; and the slope is ensured to be in an effective and stable state.

Description

Technical Field

[0001] The invention belongs to the technical field of highway slope engineering, and specifically relates to a new structure for treating roadbed landslide with reinforced modified soil and a construction method thereof. Background Art

[0002] The climate in southern my country is humid and rainfall is frequent. The soil on the highway embankment slopes is in a high moisture content state for a long time, which reduces the friction between the slope soil particles and reduces the shear strength. Specifically, rainwater infiltration will cause the soil's own weight to increase (increase in sliding force) and the shear strength to decrease (decrease in anti-sliding force), resulting in a rapid decrease in the safety factor of the slope. The shear stress on the sliding surface exceeds the shear strength of the soil, thereby causing geological disasters such as slope landslides and collapses.

[0003] Therefore, in order to ensure the strength and stability of the roadbed slope and extend the service life of the highway, it is particularly important to protect and reinforce the roadbed slope. Traditional roadbed slope protection and reinforcement technologies include retaining walls, anti-slide piles, anchor frame beams, anchor cable frame beams, skeleton protection and other supporting structures. However, the material and construction costs of traditional roadbed slope protection and reinforcement technologies are generally high, especially in large-scale projects, the cost increases significantly. At the same time, the construction process is complicated and takes a lot of time, and the construction efficiency is low. For example, the installation of anti-slide piles, anchor frame beams and anchor cable frame beams involves precise drilling and anchoring technology, which is difficult to construct and requires a high level of technical skills from the construction team.

[0004] Among them, the support height of the concrete retaining wall is limited, generally 6.0-8.0m; the construction period of anti-slide piles is long and the cost is very high; the construction of anchor frame beams and anchor cable frame beams is difficult, requires skilled workers, and is costly; the principle of the above support methods is to passively provide anti-slide support to the slope, and they all belong to rigid support. In addition, there are slope reinforcement methods such as soil nail walls, which belong to the category of flexible slope protection. Although they can adapt to partial deformation of the slope, they cannot be applied to the support of all slope landslide bodies.

[0005] Thirdly, for slopes that have already landslided or have landslide safety hazards, the existing practice is to remove the loose bodies on the slopes, and then cut the slopes to unload or slow down the slope rate or rigidly protect the slopes (or a combination of the above measures). The above existing methods have the following disadvantages:

[0006] 1. Time-consuming and labor-intensive (slope cutting and unloading, rigid protection, etc. require a long construction time and a large number of skilled workers);

[0007] 2. Occupy more land (in order to cut the slope and unload and slow down the slope, additional land needs to be acquired outside the highway);

[0008] 3. High cost (high cost of land acquisition, landslide clearing and slope protection);

[0009] 4. It is not environmentally friendly (it is necessary to re-expropriate land to meet the requirements of slowing down the slope, and to requisition a spoil site to meet the requirements of loading the loose soil of the landslide).

[0010] Therefore, for soil or soil-rock mixed slopes, it is necessary to provide an improved technical solution to address the deficiencies of the above-mentioned prior art. Invention content

[0011] The purpose of the invention is to provide a new structure of reinforced modified soil for treating roadbed landslide and a construction method thereof, so as to at least solve the above-mentioned problems existing in the prior art.

[0012] In order to achieve the above object, the present invention provides the following technical solutions:

[0013] A new structure for treating roadbed landslide with reinforced modified soil, which is formed by treating the landslide body; the new structure comprises:

[0014] A plurality of slope structure layers, each of which has a platform at the top end, and a platform ditch is arranged on each platform;

[0015] Each slope structure layer includes a plurality of compacted layer units, each compacted layer unit includes a unit interior and a unit end, wherein the unit end of each compacted layer unit forms an inclined slope surface;

[0016] A grid reinforcement layer is also provided at the bottom of each compaction layer unit, the length of the grid reinforcement layer is greater than the depth of the compaction layer unit, and the portion of the grid reinforcement layer that exceeds the compaction layer unit is reversely wrapped around the end of the unit;

[0017] A plurality of compacted layer units at the top of the new structure constitute a top waterproof layer, and a plurality of compacted layer units at the bottom constitute a bottom waterproof layer, wherein the interior and ends of the units in the top waterproof layer and the bottom waterproof layer are all compacted with modified soil;

[0018] A plurality of blind ditches are also arranged in the slope structure layer, and the blind ditches include longitudinal blind ditches and transverse blind ditches. The longitudinal blind ditches extend along the intersection of the landslide part of the soil and the non-landslide part of the soil. A plurality of transverse blind ditches are arranged on one side of the longitudinal blind ditch. The longitudinal and transverse blind ditches intersect at a certain angle, and the transverse blind ditches are connected to the longitudinal blind ditch.

[0019] The transverse blind ditch is arranged to be inclined downward, and the outlet of the transverse blind ditch is located on the slope surface; the compacted layer unit where the blind ditch is located is an intermediate drainage layer, and the intermediate drainage layer is located between the top waterproof layer and the bottom waterproof layer.

[0020] As described above, in the new structure of reinforced modified soil for treating roadbed landslide, preferably, in the compaction layer unit located between the top waterproof layer and the bottom waterproof layer, the inside and the end of the unit are compacted with modified soil.

[0021] As described above, in the new structure of reinforced modified soil for treating roadbed landslide, preferably, the blind ditch is filled with graded crushed stone so that the blind ditch has water-conducting and supporting functions.

[0022] As described above, the new structure of reinforced modified soil for treating roadbed landslide, preferably, the grid reinforcement layer is a geogrid, and the grid reinforcement layer is fixedly connected to the compaction layer unit by U-shaped nails;

[0023] The modified soil is formed by adding 10% to 20% of the mass of the raw soil into the raw soil and stirring the mixture uniformly.

[0024] As described above, the new structure for treating roadbed landslide with reinforced modified soil is preferably provided with a plurality of rapid flow grooves on each slope structure layer, the rapid flow grooves extending along the inclination direction of the slope surface, the rapid flow grooves connecting between the platform grooves of two adjacent platforms, and the outlet of the transverse blind groove is located on the rapid flow grooves;

[0025] A drainage ditch is arranged at the bottom of the new landslide structure, and the rapids trough on the bottom slope structure layer is connected with the drainage ditch.

[0026] The present application also provides a construction method for a new structure of reinforced modified soil for treating roadbed landslides. The construction method is a construction method for the above-mentioned new structure of reinforced modified soil for treating roadbed landslides. The construction method comprises the following steps:

[0027] Step 1: First, re-survey the guide rails and leveling points to determine the longitudinal and transverse axes of the road section and the plane position of the new landslide structure, then excavate the base platform where the new landslide structure is located and prepare for construction;

[0028] Step 2, starting to construct the slope structure layer step by step on the base platform, wherein the slope structure layer is constructed from multiple compaction layer units from bottom to top and compacted layer by layer; when constructing a compaction layer unit, first lay a grid reinforcement layer, and fix the grid reinforcement layer by U-shaped nails; then backfill the soil on the grid reinforcement layer layer by layer, and compact it layer by layer to form the unit interior and unit end; after the soil of a compaction layer unit is compacted, the grid reinforcement layer of the extra compaction layer unit is reversely wrapped at the compacted unit end, and U-shaped nails are driven into the reversed part of the grid reinforcement layer for fixing; until the construction of a compaction layer unit is completed, repeat the above steps to complete the construction of all compaction layer units in the entire new structure; and construct a blind ditch in the set compaction layer unit;

[0029] Step 3: construct a platform ditch on a platform at the end of the top surface of each layer of the slope structure layer, construct a rapid flow trough on the inclined slope of the slope structure layer, and connect the platform ditches of two adjacent layers through the rapid flow trough; and construct a drainage ditch at the bottom of the new structure of the landslide;

[0030] Step 4: dig a drainage ditch on the top of the new landslide structure and lay a geotextile;

[0031] Step 5: After the platform ditch, rapids trough and drainage ditch are constructed and maintained, the humus, fertilizer, water retaining agent and grass seed mixture are evenly mixed, and the grass seeds are mixed on the slope surface of each slope structure layer, and the slope surface is continuously watered and maintained.

[0032] In the construction method of the new structure of reinforced modified soil for treating roadbed landslide as described above, preferably, when constructing the compacted layer unit where the middle drainage layer is located, after the backfill and compaction of the soil is completed, a longitudinal blind ditch and a transverse blind ditch are opened on the upper surface of the compacted layer unit, and graded crushed stone is filled in the blind ditch, and finally the grid reinforcement layer of the extra compacted layer unit is reversely wrapped around the end of the compacted unit.

[0033] In the construction method of the new structure of reinforced modified soil for treating roadbed landslide as described above, preferably, the entire layer in the compacted layer unit where the middle drainage layer, the top waterproof layer and the bottom waterproof layer are located is constructed with modified soil; in the compacted layer units other than the middle drainage layer, the top waterproof layer and the bottom waterproof layer, the inside of the unit is backfilled and compacted with plain soil, and the end of the unit is backfilled and compacted with modified soil.

[0034] In the construction method of the new structure of reinforced modified soil for treating roadbed landslide as described above, preferably, the stability of the new structure is verified, and the active earth pressure of the slope is calculated using the Rankine earth pressure theory, assuming that the new structure is in a limit equilibrium state:

[0035]

[0036]

[0037] Where: soil internal friction angle Soil cohesion c, soil unit weight γ d , active earth pressure of slope Pa, refers to Rankine earth pressure coefficient Ka;

[0038] The slope sliding force is usually expressed by the horizontal component of the active earth pressure:

[0039] F S =P a cos(β) (3);

[0040] Where: slope angle β;

[0041] The anti-slip force is composed of the cohesion and the pull-out resistance of the reinforcement material:

[0042]

[0043] Where: slope height H, slope length L, reinforcement belt pull-out strength T, grid reinforcement layer number n, slope stability coefficient K;

[0044]

[0045] In the construction method of the new structure of reinforced modified soil for treating roadbed landslide as described above, preferably, the relationship between the number of soil compaction and stability is verified as follows:

[0046] n2= 0.0015e 0.1095Kn R 2 =0.97 (6)

[0047] Where: K n is the degree of compaction, n2 is the number of layered compaction, and R is the formula fitting degree;

[0048] Ignoring the energy dissipation during the compaction process, it can be assumed that the energy required to achieve the same compaction degree by indoor compaction test and on-site excavator compaction is the same:

[0049]

[0050] E 挖 = M × V (8);

[0051] E 落锤 = m 落锤 ×g×h (9);

[0052] Where: n3 is the number of times the excavator compacts the layers on site; E 落锤 is the compaction work of the drop hammer in the compaction test, m 落锤 is the mass of the falling weight, g is the acceleration due to gravity, h is the height of the falling weight, E 挖 is the compaction work of the excavator, M is the compaction mass of the excavator, and V is the compaction degree of the compacted area of ​​the excavator;

[0053] With the help of the compaction calculation formula, the relationship between the active earth pressure of the reinforced soil slope and the number of compaction times of the excavator is established:

[0054] γ d =γ dmax K n (10);

[0055] Where: K n is the compaction degree, the maximum dry density of soil γ dmax ;

[0056] Substituting equations (8) and (9) into equation (7), we can obtain the relationship between the number of rolling times and the safety factor:

[0057]

[0058] Beneficial effects:

[0059] The new structure is formed by re-treating the slope where landslide has occurred. The new structure modifies the slope soil and sets a grid reinforcement layer and a blind ditch structure during the slope reconstruction process, so that the new structure forms a semi-flexible and semi-rigid protective structure, improves the overall strength and drainage performance of the new structure, and thus makes the new structure have better stability. Through numerical simulation analysis, it can be determined that the new structure has a higher stability coefficient. The new structure uses the landslide soil (original soil) as raw material for modification construction, with low construction cost, good economy and obvious environmental benefits.

[0060] In the new structure of the landslide, the topmost layer and the bottommost layer are respectively provided with a top waterproof layer and a bottom waterproof layer, which can better prevent rain and groundwater from penetrating into the new structure. The blind ditch is provided between the top waterproof layer and the bottom waterproof layer, and the water inside the new structure of the landslide can be better discharged through the blind ditch, avoiding the interior of the slope being in a high water content state for a long time, thereby ensuring that the slope can always be in an effective and stable state. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The drawings constituting part of the present application are used to provide a further understanding of the invention. The exemplary embodiments and descriptions of the invention are used to explain the invention and do not constitute an improper limitation on the invention. Among them:

[0062] Figure 1 A schematic cross-sectional view of a new structure of reinforced modified soil for treating roadbed landslide according to an embodiment of the present invention;

[0063] Figure 2 A schematic diagram of a new structure for treating roadbed landslide with reinforced modified soil according to an embodiment of the present invention;

[0064] Figure 3 A finite element analysis diagram of the safety factor of a new structure of reinforced modified soil for treating roadbed landslide according to an embodiment of the present invention;

[0065] Figure 4 The present invention provides a flow chart of a construction method of a new structure of reinforced modified soil for treating roadbed landslide according to an embodiment of the present invention.

[0066] In the figure: 1. Compacted layer unit; 2. Transverse blind ditch; 3. Platform ditch; 4. Grid reinforcement layer; 5. Drainage ditch; 6. Longitudinal blind ditch; 7. Rapids trough. DETAILED DESCRIPTION

[0067] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0068] In the description of the present invention, the terms "longitudinal", "lateral", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, they can be fixedly connected or detachably connected; they can be directly connected or indirectly connected through intermediate components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0069] The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. It should be noted that the embodiments and features in the embodiments of the present invention can be combined with each other without conflict.

[0070] According to the specific embodiments of the present invention, Figure 1-4 As shown, the present invention provides a new structure for treating roadbed landslide with reinforced modified soil, and the new structure comprises:

[0071] There are multiple slope structure layers, and the top end of each slope structure layer has a platform, and a platform ditch 3 is arranged on each platform; in this embodiment, the platform ditch 3 is parallel to the extension direction (longitudinal direction) of the protective structure, and the platform ditch 3 is used to collect and guide rainwater flowing down from the upstream slope structure layer.

[0072] Each slope structure layer includes a plurality of compacted layer units 1, each compacted layer unit 1 includes a unit interior and a unit end, wherein the unit end of each compacted layer unit 1 forms an inclined slope surface;

[0073] A grid reinforcement layer 4 is also provided at the bottom of each compaction layer unit 1. The length of the grid reinforcement layer 4 is greater than the depth of the compaction layer unit 1. The portion of the grid reinforcement layer 4 that exceeds the compaction layer unit 1 is reversely wrapped around the end of the unit.

[0074] In the new structure, several compacted layer units 1 at the top constitute a top waterproof layer, and several compacted layer units 1 at the bottom constitute a bottom waterproof layer. The inside and ends of the units in the top waterproof layer and the bottom waterproof layer are all compacted with modified soil;

[0075] A plurality of blind ditches are also arranged in the slope structure layer, and the blind ditches include a longitudinal blind ditch 6 and a transverse blind ditch 2. The longitudinal blind ditch 6 extends along the intersection of the landslide part of the soil and the non-landslide part of the soil. A plurality of transverse blind ditches 2 are arranged on one side of the longitudinal blind ditch 6. The longitudinal and transverse blind ditches 2 intersect at a certain angle, and the transverse blind ditches 2 are connected to the longitudinal blind ditch 6.

[0076] The transverse blind ditch 2 is tilted downward (at a certain angle), and the outlet of the transverse blind ditch 2 is located on the slope; the compacted layer unit 1 where the blind ditch is located is an intermediate drainage layer, and the intermediate drainage layer is located between the top waterproof layer and the bottom waterproof layer. In this embodiment, the new structure is mainly used in soil or soil-rock mixed slopes, and the new structure is constructed on a compacted layer with a certain support foundation, or on a shoulder wall structure, to ensure that the new structure is well supported.

[0077] The new structure is formed by re-treating the slope where landslide has occurred. The new structure modifies the slope soil, and in the process of re-constructing the slope, a grid reinforcement layer 4 and a blind ditch structure are set, so that the new structure forms a semi-flexible and semi-rigid protective structure, improves the overall strength and drainage performance of the new structure, and thus makes the new structure have better stability. Through numerical simulation analysis, it can be determined that the new structure has a higher stability coefficient, and the new structure uses the landslide soil (original soil) as raw material for modification construction, with low construction cost, good economy and obvious environmental benefits.

[0078] In other embodiments, the new structure can also be applied to slopes with landslide safety hazards, or other places where needed.

[0079] In the new structure, the modified soil has better compressive strength, shear strength, and better anti-seepage and anti-scouring properties, and the density of the modified soil and the plain soil is not much different. The use of modified soil to construct the unit end of each compaction layer unit 1 can not only make the whole landslide structure better prevent rainwater from penetrating into the interior, and play a better rainproof and waterproof role, but also the new landslide structure constructed by using modified soil in combination with the grid reinforcement layer 4 has better overall structural strength.

[0080] In the new structure of the landslide, the topmost layer and the bottommost layer are respectively provided with a top waterproof layer and a bottom waterproof layer, which can better prevent rain and groundwater from penetrating into the new structure. The blind ditch is provided between the top waterproof layer and the bottom waterproof layer, and the water inside the new structure of the landslide can be better discharged through the blind ditch, avoiding the interior of the slope being in a high water content state for a long time, thereby ensuring that the slope can always be in an effective and stable state.

[0081] In addition, a grid reinforcement layer 4 is spread at the bottom of each compacted layer unit 1, and the grid reinforcement layer 4 is wrapped around the end of the unit, which can adapt to slight deformations and effectively avoid soil erosion on the slope. It not only greatly enhances the overall structural strength of the new landslide structure and improves the shear resistance of the entire new landslide structure; but also makes the new landslide structure have better integrity and erosion resistance.

[0082] Moreover, if only modified soil (without geogrid) is used to treat the landslide structure, although the strength and anti-scouring performance of the landslide structure can be improved, the rigidity of the landslide structure will increase, while the flexibility will decrease, and thus the landslide structure after treatment will not be allowed to undergo slight deformation; and if only a reinforced layer is used in slope treatment, there will be problems such as rainwater infiltration and poor durability; the present application is a new structure for treating landslides by combining modified soil, a reinforced layer and an internal blind ditch, so that the new landslide structure forms a semi-flexible and semi-rigid overall structure, thereby greatly reducing the impact of slight displacements on slope stability.

[0083] The new structure for landslide treatment completely abandons the existing technical concepts of traditional retaining walls, anti-slide piles, anchor frame beams, anchor cable frame beams, skeleton protection and other supporting structures. In the present application, all compaction layer units 1 are constructed with modified soil in combination with a grid reinforcement layer 4. Specifically, each compaction layer unit 1 of the new landslide structure is constructed with modified soil, and a grid reinforcement layer 4 is laid at the bottom of each compaction layer unit 1, and the grid reinforcement layer 4 is reversely wrapped at the end of the unit; the waterproof performance and overall structural strength of the entire new landslide structure are improved, and the entire new landslide structure has better integrity and anti-slip performance, which can effectively avoid damage such as landslides on the slope and greatly improve the stability of the slope.

[0084] In other embodiments, in the compacted layer unit 1 between the top waterproof layer and the bottom waterproof layer, the interior of the unit is compacted with plain soil, and the end of the unit is compacted with modified soil. Among them, the unit ends of the compacted layer unit 1 between the top waterproof layer and the bottom waterproof layer are compacted with modified soil, which can ensure that the new landslide structure has good rainwater penetration resistance. On this basis, the interior of the compacted layer unit 1 between the top waterproof layer and the bottom waterproof layer is built with plain soil, which can greatly reduce the construction cost. On the basis of ensuring that the new landslide structure has good stability, it can be more suitable for larger slope projects.

[0085] In other embodiments, in the compacted layer unit 1 located between the top waterproof layer and the bottom waterproof layer, the unit ends of two adjacent compacted layer units 1 can be constructed alternately with plain soil and modified soil. Such a setting can ensure that the new landslide structure has good structural strength and stability, and can also further reduce the construction cost of the new landslide structure.

[0086] The blind ditch is filled with graded crushed stone so that the blind ditch has water-conducting and supporting functions. In one embodiment of the present application, since the porosity of the graded crushed stone is relatively large, it is not only convenient for the water inside the slope to penetrate into the blind ditch and be guided by the blind ditch to drain out of the slope, but also the blind ditch constructed with graded crushed stone has better support, which can ensure that the new structure has sufficient structural strength.

[0087] The grid reinforcement layer 4 is a geogrid, and the grid reinforcement layer 4 is fixedly connected to the compaction layer unit 1 by U-shaped nails; in one embodiment of the present application, the geogrid can be a glass fiber grid, and the grid reinforcement layer 4 is arranged in the compaction layer unit 1, and the grid reinforcement layer 4 is wrapped around the unit end of the compaction layer unit 1, so that the grid reinforcement layer 4 can be used as a skeleton structure in the slope structure layer, and the part of the grid reinforcement layer 4 after being wrapped is covered by the compaction layer unit 1 of the upper layer, which can greatly enhance the integrity of the slope protection structure, and improve the structural strength of the slope protection structure, so that the slope protection structure has better anti-slip properties.

[0088] In this embodiment, the modified soil is formed by mixing cement with the original soil excavated in situ. Specifically, the modified soil is formed by adding 10% to 20% of the mass of the cement to the original soil and stirring evenly. In one embodiment of the present application, different proportions of cement are added to the original soil of different properties in different regions and stirred evenly, so that the modified soil has better compressive strength, shear strength and better anti-seepage and anti-scouring properties.

[0089] In other embodiments, the modified soil may also be combined with the plain soil using lime or other solidifying agents.

[0090] Specifically, during the mixing process of cement and plain soil, a sprinkler truck is used to supply water, and the water volume is controlled manually. After adding a small amount of water, an excavator is used to mix the modified soil evenly; the mixed modified soil is returned to the previously excavated base platform in layers and compacted in layers.

[0091] A plurality of rapids grooves 7 are arranged on each slope structure layer, and the rapids grooves 7 extend along the inclination direction of the slope surface. The rapids grooves 7 are connected between the platform grooves 3 of two adjacent platforms, and the outlet of the transverse blind groove 2 is located on the rapids grooves 7. In one embodiment of the present application, the water flow in the platform groove 3 of the upper layer can flow to the platform groove 3 of the next layer through the rapids grooves 7, playing the role of collecting and guiding the water flow.

[0092] In this embodiment, the longitudinal blind ditch 6 extends along the extension direction of the road, and multiple transverse blind ditches 2 are connected between the longitudinal blind ditch 6 and the rapids trough 7, so that the longitudinal blind ditch 6 cooperates with the transverse blind ditch 2 to guide the water flow inside the new structure of the landslide to the rapids trough 7 for discharge.

[0093] A drainage ditch 5 is provided at the bottom of the new landslide structure, and a rapids trough 7 on the bottom slope structure layer is connected to the drainage ditch 5. In one embodiment of the present application, a drainage ditch 5 is provided at the bottom of the new landslide structure to divert water flow and prevent water flow from gathering at the bottom of the new landslide structure.

[0094] The present application also provides a construction method for a new structure of reinforced modified soil for treating roadbed landslides. The construction method is a construction method for a new structure of reinforced modified soil for treating roadbed landslides. The construction method comprises the following steps:

[0095] Step 1: First re-survey the guide rails and leveling points to determine the longitudinal and transverse axes of the road section and the plane position of the new landslide structure, then excavate the base platform where the new landslide structure is located and prepare for construction; in this embodiment, the base platform can be a compacted layer of a certain thickness, or a structure with sufficient support such as a shoulder wall. The construction preparation work specifically includes: setting construction control points and marking the backfill thickness and slope of each layer.

[0096] At the same time, the excavated soil is modified by adding cement at a dosage of 10% to 20%, and the excavator bucket is used for mixing to ensure the uniformity of the filler and improve the engineering properties of the excavated soil. The modified soil is transported and deployed to the backfill position by the excavator. Among them, the modified soil construction method uses an excavator or a forklift to stir 6 times. Water should be sprinkled and mixed during the 3rd to 6th stirring. The moisture content is about 40%, and the modified soil is mixed according to the daily usage.

[0097] Step 2, starting to construct the slope structure layer step by step on the base platform, wherein the slope structure layer is constructed from multiple compaction layer units 1 from bottom to top and compacted layer by layer; when constructing a compaction layer unit 1, first lay a grid reinforcement layer 4, and fix the grid reinforcement layer 4 with U-shaped nails; then backfill the soil on the grid reinforcement layer 4 layer by layer, and compact it layer by layer to form the unit interior and unit end. After the soil of a compaction layer unit 1 is compacted, the grid reinforcement layer 4 of the extra compaction layer unit 1 is reversely wrapped at the compacted unit end and drive U-shaped nails into the grid reinforcement layer 4 of the reversed part for fixing; until the construction of one compaction layer unit 1 is completed, repeat the above steps to complete the construction of all compaction layer units 1 in the entire new structure; and construct a blind ditch in the set compaction layer unit 1; in this embodiment, in each compaction layer unit 1, the thickness of the backfilled modified soil is 25 to 40CM each time, and the backfill is divided into two times, and the thickness of each compaction layer unit 1 is 50 to 80CM, wherein the reversed thickness of the grid reinforcement layer 4 is the thickness of the compaction layer unit 1.

[0098] Specifically, in this embodiment, the slope has a total of 18 compaction layer units 1. When constructing a compaction layer unit 1, the soil can be first laid loosely to a certain thickness, and then compacted and leveled with an excavator bucket to form a first compaction layer, and then loose soil is laid and compacted and leveled with an excavator to form a second layer. The two compaction layers form a compaction layer unit 1. Before compacting the modified soil, add an appropriate amount of water to the modified soil to keep the modified soil at a suitable humidity, so that the modified soil has a better compaction effect.

[0099] After the modified soil is filled, it is leveled with an excavator. After leveling, if the moisture content is lower than 40%, water is sprinkled. When the moisture reaches 40%, it is rolled with the excavator track. Rolling is done several times. After rolling, the slope is trimmed. After the slope is trimmed, the reserved reversed grid reinforcement layer 4 is reversed and laid. Repeat the above process until the top layer of the slope. The waterproof layer on the top of the slope is constructed by filling with modified soil. The grid reinforcement layer 4 may not be laid depending on the situation. The top waterproof layer of the slope mainly plays the role of sealing the top surface.

[0100] Step 3, constructing a platform ditch 3 on a platform at the end of the top surface of each layer of the slope structure layer, constructing a torrent trough 7 on the inclined slope of the slope structure layer, connecting the platform ditches 3 of two adjacent layers through the torrent trough 7; and constructing a drainage ditch 5 at the bottom of the new landslide structure; in this embodiment, a longitudinal blind ditch 6 is arranged inside the new landslide structure, and the longitudinal blind ditch 6 and the torrent trough 7 are connected through the transverse blind ditch 2, so as to realize the internal drainage system of the new landslide structure, and the water inside the new landslide structure can be discharged in time; at the same time, the new landslide structure as a whole is constructed with modified soil and a grid reinforcement layer 4, so that the new landslide structure as a whole has good rainwater anti-seepage performance, and on this basis, with the external drainage structures such as the torrent trough 7, the platform ditch 3 and the drainage ditch 5 arranged on the new landslide structure, the new landslide structure has a good internal and external integrated drainage system.

[0101] Step 4: dig a drainage ditch on the top of the new landslide structure and lay a geotextile; this is used to guide water to the drainage ditches 5 on both sides of the top of the new landslide structure in time during heavy rains to ensure smooth drainage.

[0102] Step 5, after the platform ditch 3, the rapids trough 7 and the drainage ditch 5 are constructed and maintained, the humus soil, fertilizer, water retaining agent, and grass seed mixed materials are stirred evenly, and grass seeds are mixed on the slope surface of each layer of the slope structure layer, and the slope surface is continuously watered and maintained. In the present embodiment, a watering truck is used to wet the slope surface, and after the mixed materials such as humus soil, fertilizer, water retaining agent, and grass seeds are stirred, grass seeds are mixed on each level of the slope surface. The mixed grass seeds are selected to be mixed and sprayed with characteristics such as deep roots and shallow roots, legumes and gramineous, and foreign and local, so that they are evenly sprayed on each level of the slope surface. After the grass seed spraying is completed, the slope surface is covered with non-woven fabrics to play a role in heat preservation and moisture retention and promoting plant growth. During the period from the germination of plant seeds to the seedlings, watering and maintenance are required to keep the soil moist.

[0103] When the compacted layer unit 1 where the middle drainage layer is located is constructed, after the backfill and compaction of the soil is completed, a longitudinal blind ditch 6 / longitudinal blind ditch 6 is opened on the upper surface of the compacted layer unit 1, and graded crushed stone is filled in the blind ditch, and finally the grid reinforcement layer 4 of the extra compacted layer unit 1 is reversely wrapped around the end of the compacted unit. In one embodiment of the present application, the graded crushed stone is filled in the blind ditch, so that the waterproof layer has better support, which makes it easier to continue to construct the compacted layer unit 1 above the waterproof layer.

[0104] In this embodiment, the new structure has a total of 18 compacted layer units 1, the lowest compacted layer unit 1 is the bottom waterproof layer, the top compacted layer unit 1 is the top plate waterproof layer, and the intermediate drainage layer can be composed of multiple layers of blind ditch / gravel layers. The number and specific layers of the intermediate drainage layers can be set according to the internal drainage needs of the new landslide structure. Specifically, in this embodiment, the second and twelfth layers can be set as waterproof layers with blind ditches.

[0105] In other embodiments of the present application, the entire compacted layer unit 1 where the middle drainage layer, the top waterproof layer, and the bottom waterproof layer are located is constructed with modified soil; in the compacted layer units 1 other than the middle drainage layer, the top waterproof layer, and the bottom waterproof layer, the interior of the unit is backfilled and compacted with plain soil, and the end of the unit is backfilled and compacted with modified soil. Among them, only the middle drainage layer, the top waterproof layer, and the bottom waterproof layer are backfilled and compacted with modified soil, and the rest of the compacted layer units 1 are constructed with plain soil inside the unit and modified soil at the end of the unit, which can greatly save construction costs and is suitable for large-scale slope projects.

[0106] The stability of the new structure is checked. Assuming that the new structure is in a limit equilibrium state, the active earth pressure of the slope is calculated using the Rankine earth pressure theory:

[0107]

[0108]

[0109] Where: soil internal friction angle Soil cohesion c, soil unit weight γ d , active earth pressure of slope Pa, refers to Rankine earth pressure coefficient Ka;

[0110] The slope sliding force is usually expressed by the horizontal component of the active earth pressure:

[0111] F S =P a cos(β) (3);

[0112] Where: slope angle β;

[0113] The anti-slip force is composed of the cohesion and the pull-out resistance of the reinforcement material:

[0114]

[0115] Where: slope height H, slope length L, reinforcement belt pull-out strength T, grid reinforcement layer number n, slope stability coefficient K;

[0116]

[0117] In this example, the slope height and slope foot are 10 m and 30° respectively, and the cohesion, internal friction angle and gravity of the modified soil are 35°, 20 kPa and 18 kN / m respectively. 3, the tensile strength and number of layers of the reinforcement material of the grid reinforcement layer 4 are 50 kN / m and 3 layers respectively. Based on the above calculation formula, the Rankine earth pressure is 190.8 kN / m, the sliding force is 165.12 kN / m, and the anti-sliding force is 259.81 kN / m. Therefore, the safety factor of the slope after treatment can be calculated to be 1.57, indicating that the slope after treatment has stability.

[0118] The relationship between soil compaction times and stability is verified as follows:

[0119] n2= 0.0015e 0.1095Kn R 2 =0.97 (6)

[0120] Where: K n is the degree of compaction, n2 is the number of layered compaction, and R is the formula fitting degree;

[0121] Ignoring the energy dissipation during the compaction process, it can be assumed that the energy required to achieve the same compaction degree by indoor compaction test and on-site excavator compaction is the same:

[0122]

[0123] E 挖 = M × V (8);

[0124] E 落锤 = m 落锤 ×g×h (9);

[0125] Where: n3 is the number of times the excavator compacts the layers on site; E 落锤 is the compaction work of the drop hammer in the compaction test, m 落锤 is the mass of the falling weight, g is the acceleration due to gravity, h is the height of the falling weight, E 挖 is the compaction work of the excavator, M is the compaction mass of the excavator, and V is the compaction degree of the compacted area of ​​the excavator;

[0126] With the help of the compaction calculation formula, the relationship between the active earth pressure of the reinforced soil slope and the number of compaction times of the excavator is established:

[0127] γ d =γ dmax K n (10);

[0128] Where: K n is the compaction degree, the maximum dry density of soil γ dmax ;

[0129] Substituting equations (8) and (9) into equation (7), we can obtain the relationship between the number of rolling times and the safety factor:

[0130]

[0131] In order to analyze the effectiveness of the reinforced modified soil slope, ABAQUS software is used in this embodiment to simulate the safety analysis of the slope before and after reinforcement. First, the numerical calculation model is pre-processed, including the establishment of the analysis model and mesh division. After the mesh division is completed, the set material model and parameters are assigned to the unit grid, and the boundary conditions are set according to the calculation requirements. According to the above modeling method and steps, the effectiveness of the reinforced modified soil slope is analyzed, and the stress and displacement cloud diagrams are generated to verify the effectiveness of the reinforced modified soil slope; Figure 3 As shown, the finite element analysis results show that the safety factor of the original slope structure is 0.97, and the slope is prone to landslides; the safety factor of the new structure of the landslide reinforced in this application is about 1.24, indicating that the new structure of the landslide has better stability and is not prone to landslides.

[0132] It should be understood that the above description is merely exemplary and the embodiments of the present application do not limit this.

[0133] 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 principle of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A new structure for treating roadbed landslide with reinforced modified soil, characterized in that: A new structure is formed by treating the landslide body; the new structure includes: A plurality of slope structure layers, each of which has a platform at the top end, and a platform ditch is arranged on each platform; Each slope structure layer includes a plurality of compacted layer units, each compacted layer unit includes a unit interior and a unit end, wherein the unit end of each compacted layer unit forms an inclined slope surface; A grid reinforcement layer is also provided at the bottom of each compaction layer unit, the length of the grid reinforcement layer is greater than the depth of the compaction layer unit, and the portion of the grid reinforcement layer that exceeds the compaction layer unit is reversely wrapped around the end of the unit; A plurality of compacted layer units at the top of the new structure constitute a top waterproof layer, and a plurality of compacted layer units at the bottom constitute a bottom waterproof layer, wherein the interior and ends of the units in the top waterproof layer and the bottom waterproof layer are all compacted with modified soil; A plurality of blind ditches are also arranged in the slope structure layer, and the blind ditches include longitudinal blind ditches and transverse blind ditches. The longitudinal blind ditches extend along the intersection of the landslide part of the soil and the non-landslide part of the soil. A plurality of transverse blind ditches are arranged on one side of the longitudinal blind ditch. The longitudinal and transverse blind ditches intersect at a certain angle, and the transverse blind ditches are connected to the longitudinal blind ditch. The transverse blind ditch is arranged to be inclined downward, and the outlet of the transverse blind ditch is located on the slope surface; the compacted layer unit where the blind ditch is located is an intermediate drainage layer, and the intermediate drainage layer is located between the top waterproof layer and the bottom waterproof layer.

2. The new structure for treating roadbed landslide with reinforced modified soil according to claim 1 is characterized in that: In the compacted layer unit located between the top waterproof layer and the bottom waterproof layer, the inside of the unit and the end of the unit are compacted with modified soil.

3. The new structure for treating roadbed landslide with reinforced modified soil according to claim 2 is characterized in that: The blind ditch is filled with graded crushed stones so that the blind ditch has water guiding and supporting functions.

4. The new structure for treating roadbed landslide with reinforced modified soil according to claim 3 is characterized in that: The grid reinforcement layer is a geogrid, and the grid reinforcement layer is fixedly connected to the compaction layer unit by U-shaped nails; The modified soil is formed by adding 10% to 20% of the mass of the raw soil into the raw soil and stirring the mixture uniformly.

5. The new structure for treating roadbed landslide with reinforced modified soil according to claim 3 is characterized in that: A plurality of rapid flow grooves are arranged on each slope structure layer, the rapid flow grooves extend along the inclination direction of the slope surface, the rapid flow grooves are connected between the platform grooves of two adjacent platforms, and the outlets of the transverse blind grooves are located on the rapid flow grooves; A drainage ditch is arranged at the bottom of the new landslide structure, and the rapids trough on the bottom slope structure layer is connected with the drainage ditch.

6. A construction method for a new structure of reinforced modified soil for treating roadbed landslide, characterized in that: The construction method is a construction method for the new structure of reinforced modified soil for treating roadbed landslide according to any one of claims 1 to 5, and the construction method comprises the following steps: Step 1: First, re-survey the guide rails and leveling points to determine the longitudinal and transverse axes of the road section and the plane position of the new landslide structure, then excavate the base platform where the new landslide structure is located and prepare for construction; Step 2, starting to construct the slope structure layer step by step on the base platform, wherein the slope structure layer is constructed from multiple compaction layer units from bottom to top and compacted layer by layer; when constructing a compaction layer unit, first lay a grid reinforcement layer, and fix the grid reinforcement layer by U-shaped nails; then backfill the soil on the grid reinforcement layer layer by layer, and compact it layer by layer to form the unit interior and unit end; after the soil of a compaction layer unit is compacted, the grid reinforcement layer of the extra compaction layer unit is reversely wrapped at the compacted unit end, and U-shaped nails are driven into the reversed part of the grid reinforcement layer for fixing; until the construction of a compaction layer unit is completed, repeat the above steps to complete the construction of all compaction layer units in the entire new structure; and construct a blind ditch in the set compaction layer unit; Step 3: construct a platform ditch on a platform at the end of the top surface of each layer of the slope structure layer, construct a rapid flow trough on the inclined slope of the slope structure layer, and connect the platform ditches of two adjacent layers through the rapid flow trough; and construct a drainage ditch at the bottom of the new structure of the landslide; Step 4: dig a drainage ditch on the top of the new landslide structure and lay a geotextile; Step 5: After the platform ditch, rapids trough and drainage ditch are constructed and maintained, the humus, fertilizer, water retaining agent and grass seed mixture are evenly mixed, and the grass seeds are mixed on the slope surface of each slope structure layer, and the slope surface is continuously watered and maintained.

7. The construction method of the new structure of reinforced modified soil for treating roadbed landslide according to claim 6 is characterized in that: When constructing the compacted layer unit where the middle drainage layer is located, after the backfill and compaction of the soil is completed, a longitudinal blind ditch and a transverse blind ditch are opened on the upper surface of the compacted layer unit, and graded crushed stone is filled in the blind ditch. Finally, the grid reinforcement layer of the extra compacted layer unit is reversely wrapped around the end of the compacted unit.

8. The construction method of the new structure of reinforced modified soil for treating roadbed landslide according to claim 7 is characterized in that: The entire compacted layer unit where the middle drainage layer, top waterproof layer and bottom waterproof layer are located is constructed with modified soil; in the compacted layer units other than the middle drainage layer, top waterproof layer and bottom waterproof layer, the interior of the unit is backfilled and compacted with plain soil, and the end of the unit is backfilled and compacted with modified soil.

9. The construction method of the new structure of reinforced modified soil for treating roadbed landslide according to claim 6 is characterized in that: The stability of the new structure is checked. Assuming that the new structure is in a limit equilibrium state, the active earth pressure of the slope is calculated using the Rankine earth pressure theory: Where: soil internal friction angle Soil cohesion c, soil unit weight γ d , active earth pressure of slope Pa, refers to Rankine earth pressure coefficient Ka; The slope sliding force is usually expressed by the horizontal component of the active earth pressure: F S =P a cos(β) (3); Where: slope angle β; The anti-slip force is composed of the cohesion and the pull-out resistance of the reinforcement material: Where: slope height H, slope length L, reinforcement belt pull-out strength T, grid reinforcement layer number n, slope stability coefficient K; 10. The construction method of the new structure of reinforced modified soil for treating roadbed landslide according to claim 6 is characterized in that: The relationship between soil compaction times and stability is verified as follows: Where: K n is the degree of compaction, n2 is the number of layered compaction, and R is the formula fitting degree; Ignoring the energy dissipation during the compaction process, it can be assumed that the energy required to achieve the same compaction degree by indoor compaction test and on-site excavator compaction is the same: AND 挖 = M×V (8); HAVE BEEN 落锤 = m 落锤 ×g×h (9); Where: n3 is the number of times the excavator compacts the layers on site; E 落锤 is the compaction work of the drop hammer in the compaction test, m 落锤 is the mass of the falling weight, g is the acceleration due to gravity, h is the height of the falling weight, E 挖 is the compaction work of the excavator, M is the compaction mass of the excavator, and V is the compaction degree of the compacted area of ​​the excavator; With the help of the compaction calculation formula, the relationship between the active earth pressure of the reinforced soil slope and the number of compaction times of the excavator is established: c d =c dmax K n (10); Where: K n is the compaction degree, the maximum dry density of soil γ dmax ; Substituting equations (8) and (9) into equation (7), we can obtain the relationship between the number of rolling times and the safety factor:

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