CN110644529A - Reverse-wrapping type slag building geotextile bag retaining wall, construction method and application - Google Patents

Abstract

The invention discloses a reverse-packed construction slag geotechnical bag retaining wall, a construction method and an application, and the purpose is to solve the problem that the geotechnical bag retaining wall can play a certain reinforcement effect during the construction of the reinforced retaining wall. However, the geobags are independent individuals, lack connectivity, and have poor integrity in engineering applications; the retaining wall component is formed by sequentially connecting a reinforced section, a turn-up section, and a fixed section. The reverse-packed construction slag geobag retaining wall includes a bottom layer and a protection unit arranged on the bottom layer, and the protection unit is composed of N retaining wall components, and N≥1. This application combines geobags, geogrids and construction slag, and proposes a structure of a retaining wall with a reverse-packed construction slag geobag. The recycling of slag improves the bearing capacity and overall performance of the retaining wall, and provides a basis for the application of the reverse-packed slag geotechnical bag retaining wall in practical engineering.

Description

A kind of anti-construction slag geobag retaining wall, construction method and application

technical field

The invention relates to the field of construction slag recycling, in particular to a reverse-packed construction slag geotechnical bag retaining wall, a construction method and an application. Based on the characteristics of the construction slag, the present application provides a new reverse-packed construction slag geotechnical bag retaining wall, which has a better slope reinforcement effect and is of great significance for realizing the resource utilization of the construction slag.

Background technique

In the process of urbanization construction, due to reconstruction, expansion, demolition and other activities, a large amount of construction waste will be generated. Among them, construction waste mainly consists of solid waste such as concrete blocks, bricks, and mortar. On the other hand, with the rapid development of urbanization in my country, natural building resources are increasingly depleted. If the building slag can be recycled, it can not only solve the environmental pollution problem caused by the building slag, but also save resources and have great environmental protection benefits.

At present, two kinds of geosynthetic materials, geobags and geogrids, are widely used in practical projects. Geotextile bags are sewn from geotextiles and then filled with soil, sand, gravel, construction waste, etc. and sealed. Geobags can achieve the effect of reinforcement by constraining the deformation of soil, and have been widely used in Haikou revetment, roadbed treatment, slope protection and other projects. The grid is a two-dimensional grid made of polypropylene, polyvinyl chloride and other high molecular polymers by thermoplastic or molding, or a three-dimensional grid screen with a certain height. When used in civil engineering construction , called geogrid. Geogrid is a reinforced material that is widely used in reinforced soil structures. When it is laid in the soil, it can restrain the lateral deformation of the soil and prevent the formation of slip surfaces.

Although in actual engineering construction, geobag technology and geogrid reinforcement technology have been relatively mature, there are also some defects, which are difficult to meet engineering needs. In the construction of the reinforced retaining wall, the geobag retaining wall can play a certain reinforcement effect, but the overall performance of the geobag reinforced soil structure is poor, and it is prone to the overturning damage of the slope or the overall outward movement of the slope. etc. Destruction.

Therefore, there is an urgent need for a new device and/or method to solve the above problems.

SUMMARY OF THE INVENTION

The purpose of the invention is as follows: in the construction process of the reinforced retaining wall, the geo-bag retaining wall can play a certain reinforcement effect, but the geo-bags are independent individuals and lack connectivity, which is very difficult in engineering applications. To solve the problem of poor integrity, the invention provides an anti-construction slag geotechnical bag retaining wall, a construction method and an application. The present application combines geobags, geogrids and construction slag, and proposes a structure of a retaining wall with a reverse-packed construction slag geobag. The recycling of slag improves the bearing capacity and overall performance of the retaining wall, and provides a basis for the application of the reverse bag type slag geotechnical bag retaining wall in practical engineering.

In order to achieve the above object, the present invention adopts the following technical solutions:

A kind of anti-packing type construction slag geotechnical bag retaining wall, comprising a bottom layer and a protection unit arranged on the bottom layer, the protection unit is composed of N retaining wall components, and N≥1;

The retaining wall assembly is formed by connecting a reinforced section, a reverse wrapping section and a fixed section in sequence;

The reinforcement section includes a first geogrid laid flat and a filling soil body, and the filling soil body is located on the first geogrid;

The turn-up section includes a second geogrid and a second geobag, the second geobag is at least one and stacked together, the second geogrid is wrapped on the outside of the second geobag and the second geobag is Geo bags are connected as a whole;

The fixed section comprises a third geogrid and a third geobag that are laid flat, wherein the third geobag is at least one and is stacked together in sequence along the vertical direction, and the geobag is located on the third geogrid;

The side of the fixing section away from the reinforcement section is inclined relative to the vertical direction, and the angle between the side surface of the fixing section away from the reinforcement section and the horizontal plane is 2 to 75°;

The first geogrid, the second geogrid, and the third geogrid are connected in sequence;

The first geotechnical bag and the second geotechnical bag are respectively filled with building slag.

The first geotechnical bag and the second geotechnical bag are respectively filled with building slag composed of concrete blocks and bricks, and the mass of the concrete blocks and the rotating blocks is 1:0.25-2.

The mass of the concrete block and the rotating block is 1:0.8-1.2.

The filling degree of the slag in the first geotechnical bag and the second geotechnical bag is 65-90%.

The filling degree of the slag in the first geotechnical bag and the second geotechnical bag is 80%.

The height of the retaining wall assembly is 0.2-3.5m.

In the fixing section, two adjacent layers of third geotechnical bags are arranged in a staggered manner.

The angle between the side surface of the fixing section away from the reinforcement section and the horizontal plane is 15-35°.

The side of the retaining wall assembly away from the reinforced section is large at the bottom and small at the top.

The second geobags are stacked together to form a second stack, and the second geogrid is wrapped on the outer surface of the second stack.

The upper end point of the side face of the fixing section away from the reinforced section is located between the lower end point of the side face of the fixing section away from the reinforced section and the turn-up section.

The protection unit is formed by stacking at least two retaining wall assemblies in a vertical direction;

In the direction from bottom to top, the retaining wall components are recorded as the first retaining wall component structure, ... the Nth retaining wall component, and N≥2;

The first geogrid of the first retaining wall assembly is tiled on the bottom layer, and the first geogrid of the Nth retaining wall assembly is tiled on the filling soil of the N-1th retaining wall assembly;

One side of the upper fixed section of the protection unit is in the shape of a large bottom and a small top.

The bottom layer is a soil layer or a cement layer.

The length of the first geogrid is 0.1-10m.

The reinforced section is located on the side close to the slope body, and the fixed section is located on the side away from the slope body.

The turn-up section is formed by stacking two to six layers of second geotextile bags in turn; the fixed section is formed by stacking two to six layers of third geotechnical bags in the vertical direction.

The first geogrid, the second geogrid and the third geogrid are integrally formed.

A construction method for a reverse-packed construction slag geotechnical bag retaining wall, comprising the following steps:

(1) Arrange and level the bottom layer of the place to be protected;

(2) Based on the leveled bottom layer, determine the lengths of the first geogrid, the second geogrid, and the third geogrid according to the design requirements, and select the corresponding length of the geogrid to spread on the surface of the base; Fill soil on the first geogrid to form a filled soil to form a reinforced section; stack the second geotechnical bags together to form a second stack, and wrap the second geogrid on the outside of the second stack The surface is formed into a turn-up section; the third geotextile is superimposed on the third geogrid in the vertical direction to form a fixed section; after the reinforced section, the turn-up section and the fixed section are constructed, the first retaining wall is formed components;

(3) On the basis of the first retaining wall assembly, using the upper surface of the first retaining wall assembly as the basis, repeat step (2) to form a second retaining wall assembly; repeat this until the Nth retaining wall is formed components.

In the step 2, the concrete blocks and bricks are crushed and screened by a crusher, and then loaded into the geotextile bag according to the proportion, and divided into the second geotextile bag and the third geotextile bag according to the different placement positions.

In the step 1, when there is soil in the protected place, the soil on it needs to be removed as required, and the bottom layer after the soil is removed is arranged and leveled.

In the step 2, along the direction from bottom to top, between the two adjacent layers of the third geobags, the third geobag at the bottom is away from the outer edge of the reinforcement section and the third geobag at the top is away from the reinforcement section. The outer edge is in the direction away from the stiffened section.

The application of the above-mentioned anti-construction slag geotechnical bag retaining wall.

The aforesaid turn-back type construction slag geobag retaining wall is used for slope protection.

Retaining wall refers to a structure that supports soil, prevents landslide or collapse of soil, and maintains soil stability; according to the structural form of retaining wall, it is divided into: gravity retaining wall, anchored retaining wall, thin-walled retaining wall Retaining walls, reinforced earth retaining walls, etc. Among them, the gravity retaining wall refers to the retaining wall that relies on the retaining wall's own gravity to resist the lateral pressure of the soil mass to maintain the stability of the soil slope. According to the back slope of the retaining wall, the gravity retaining wall is divided into three types: inclined, inclined and upright; The polyline wall-backed gravity retaining wall and the counterweight retaining wall of the counterweight table.

Reinforced soil retaining wall refers to a retaining wall with reinforced soil composed of three parts: fill, tie bars arranged in the fill and wall panels, which bear the lateral pressure of the soil body. Reinforced earth retaining wall is to add geogrid and other reinforcement materials to the soil, and the friction between the reinforcement material and the soil body can resist the lateral pressure of the soil body and restrain the deformation of the soil body. The reinforced material can reduce the lateral pressure generated by the soil in the soil, thereby maintaining the stability of the slope soil of the retaining wall. Reinforced earth retaining wall is a flexible retaining structure, which has great adaptability to foundation deformation and slope slippage, and the building height of its reinforced retaining wall can also be very large.

Further, scholars at home and abroad have carried out a lot of research on construction slag, but mainly apply waste concrete as recycled aggregate to reinforced concrete structural engineering and road engineering, and research on geotechnical bag retaining walls filled with construction slag. There are few research reports on it; domestic and foreign scholars have carried out extensive exploration on the turn-up retaining wall, but so far there is no research on the reinforced retaining wall connected by the turn-up type of construction slag geotechnical bags. Related research.

Therefore, based on the existing retaining wall, the present application provides a composite type that uses construction slag as a basic material and uses it as a geotechnical bag filler, which is a combination of a gravity retaining wall and a reinforced soil retaining wall. retaining wall structure. At the same time, the inventor studied the reinforcement effect of the application on the slope soil of the retaining wall through the control variable method; further, the influence of the length of the first geogrid on the reinforcement effect of the retaining wall slope was also studied. The application in the practice of slope support engineering provides a powerful reference.

In the present application, the construction slag is used as a raw material, and it is applied to the geobag side slope support project, which is beneficial to reduce the demand and dependence of the construction industry on natural resources. At the same time, the amount of slag is large, easy to obtain, and nearly zero cost, which is conducive to reducing the construction cost of the retaining wall. In addition, the construction slag geotechnical bag of the present application does not need to be maintained, can improve the construction speed, shorten the construction period, and has a good effect.

In this application, after the waste concrete blocks, bricks, etc. in the construction waste are crushed by a crusher, they are screened and put into a geotechnical bag according to the proportion to form a geotechnical bag. bags, third geo bags. In this application, both the geogrid and the geobag are flexible materials, and the geogrid can effectively restrain the lateral displacement of the soil and enhance the bearing capacity of the soil; the second and third geobags not only have certain It is water permeable and has a certain deformation ability. In this structure, through the interaction of the reinforcement section, the turn-up section and the fixed section, the mutual displacement and slippage between the geotextile bags when only the third geotechnical bag is used can be effectively suppressed; at the same time, the second geotechnical bag, the third Under the action of pressure, the slag in the bag is restrained by the tension generated by the geobag, so that the geobag has a higher compressive strength and serves the purpose of reinforcement; at the same time, the second geobag is connected with the second The geogrid is combined with the reverse bag, and a plurality of second geotechnical bags are connected into one through the second geogrid, which not only has high compressive strength, but also has good shock absorption and energy dissipation and anti-frost heave characteristics; further , The combination of the third geogrid and the third geobag, in addition to effectively preventing the construction slag in the geobag from sinking under the action of its own weight and external force, has friction between the geogrid and the soil, between the geobag and the soil , and the grid structure of the geogrid can produce interlocking and occlusal effects on the soil, thereby limiting the lateral deformation of the soil and greatly improving the bearing capacity of the soil, thereby achieving the effect of reinforcing the slope; and the third The dislocation superposition of the geobag can form slope protection for the soil, and the friction and interlocking between the geogrid and the soil can effectively ensure the stability of the soil on the slope of the retaining wall. Slope protection.

To sum up, in the present application, the construction slag is used to build a reverse-packed construction slag geotechnical bag retaining wall, which can effectively realize the resource utilization of the construction slag; The package section and the fixed section constitute a retaining wall component, thereby forming an effective slope protection. In order to verify the effect of the present application, the inventor compared the slope reinforcement effect under three different working conditions: natural soil slope, geo-bag retaining wall, and the present application's turn-back construction slag geo-bag retaining wall through model tests. The experimental results show that the retaining wall with the reverse-packed construction slag geotextile bag of the present application can enhance the bearing capacity of the soil behind the retaining wall, and can effectively restrain the settlement deformation of the slope top of the retaining wall; The retaining wall structure can enhance the overall performance of the retaining wall and can effectively restrain the lateral deformation of the retaining wall surface. In addition, under the same conditions, the longer the length of the first geogrid is, the more obvious the reinforcement effect of the slope of the retaining wall structure is. It can be seen that the present application can play an effective slope reinforcement and protection effect, and is simple in manufacture, cheap in cost, green and environmentally friendly, good in water permeability, convenient in material acquisition, and low in cost, and is especially suitable for practical projects such as seaport revetment, cofferdam protection, and slope protection. , can meet the needs of practical engineering applications, has important use value and significant social significance.

Description of drawings

The invention will be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a model groove in Example 1. FIG.

Figure 2 shows the design of the basic experimental model.

Figure 3 is a model design diagram of different lengths of the first geogrid.

Figure 4 is a diagram of a model loading device.

Figure 5 shows the layout of the dial indicator.

Figure 6 shows the layout of the earth pressure cell.

Figure 7 is a cross-sectional layout diagram.

Figure 8 shows the layout of the strain gauges.

Fig. 9 is the first geogrid laying and the second geogrid reverse wrapping diagram.

FIG. 10 is a schematic diagram of the placement of the third geobag in Example 1. FIG.

Figure 11 is a diagram of the load transfer bar.

Figure 12 is a test diagram of a natural soil slope (Condition 1).

Figure 13 is the test diagram of the retaining wall with the construction slag geotechnical bag (Condition 2).

Figure 14 is the test diagram of the 0.9m first geogrid length turn-up slag geobag retaining wall (Condition 3).

Figure 15 shows the relationship between the load on the top of the slope and the settlement on the top of the slope for working conditions 1, 2, and 3.

Figure 16 is a diagram showing the relationship between the horizontal displacement of the wall surface and the height of the retaining wall in working condition 1.

Figure 17 is a graph showing the variation rule of the horizontal displacement along the height of the retaining wall in the middle and on the edge of the slope wall in working condition 2.

Figure 18 is a graph showing the variation rule of the horizontal displacement along the height of the retaining wall in the middle and on the edge of the slope wall in working condition 3.

Figure 19 shows the lateral earth pressure distribution behind the wall of the slag geobag retaining wall (Condition 2) and the 0.9m first geogrid length of the turn-back type slag geobag retaining wall (Condition 3) Graph.

FIG. 20 is a graph of the test results of working conditions 4 and 5.

Figure 21 shows the relationship between the load on the top of the slope and the settlement on the top of the slope for working conditions 3, 4, and 5.

Figure 22 shows the relationship between the horizontal displacement of the wall surface and the height of the retaining wall in working conditions 4 and 5.

Figure 23 is the distribution diagram of the lateral earth pressure behind the retaining wall in working conditions 3, 4 and 5.

FIG. 24 is the geogrid strain curve of working condition 4. FIG.

FIG. 25 is the geogrid strain curve of working condition 3. FIG.

FIG. 26 is the geogrid strain curve of working condition 5. FIG.

Detailed ways

All features disclosed in this specification, or all disclosed steps in a method or process, may be combined in any way except mutually exclusive features and/or steps.

Any feature disclosed in this specification, unless expressly stated otherwise, may be replaced by other equivalent or alternative features serving a similar purpose. That is, unless expressly stated otherwise, each feature is but one example of a series of equivalent or similar features.

Example 1

(1) Test test

In order to verify the effect of the present application, two sets of model comparison tests are set up in this example to study the slope reinforcement effect of the reverse-packed slag geobag retaining wall, and the length ratio of the first geogrid to the reverse-packed construction of the present application. Influence of soil bag retaining wall slope reinforcement. Among them, through the model comparison test of natural soil slope, construction slag geo-bag retaining wall, and reverse-packed construction slag geo-bag retaining wall, a uniform load was applied to the top of the slope top of the retaining wall. The deformation and mechanical response under the uniform load are determined to determine the slope reinforcement effect of the reverse-packed slag geotechnical bag retaining wall. A set of model ratio tests with different lengths of the first geogrid were carried out by using the control variable method, and a uniform load was applied to the top of the slope top of the retaining wall. The magnitude and change law of top settlement displacement, lateral earth pressure and geogrid strain, etc., it is proposed to explore the influence of the length of the first geogrid on the reinforcement effect of the back-packed slag geobag retaining wall.

1 Model design and production

1.1 Test prototype and model parameters

The prototype design of the reverse-packed slag geobag retaining wall in this embodiment is a silty clay slope. In order to truly reflect the actual stress and deformation of the original slope, the test model should be similar to the structural prototype and follow the similarity theorem, so that it satisfies material similarity, load similarity, and geometric similarity. For testing and research needs, the model tank is tested at 1:4 according to the actual size, and it is used as the model of the test structure.

1.2 Model slot design

According to the similarity ratio between the structural prototype of the retaining wall and the test model is 1:4, the model groove of the test is also made according to the similarity ratio of 1:4. The size of the model groove is: length × width × height = 2.43 × 1.06 × 1.60m, the model groove material is welded with No. 12 I-beam and No. 14 I-beam, and the three sides of the model groove frame are reinforced with the same angle steel deal with. Model groove baffle The two sides of the material are wooden boards, and the front is replaced by 2.43×1.60m tempered glass, which is convenient to observe the damage change of the retaining wall during the loading process, as shown in Figure 1.

1.3 Model Design

In this test, the slope ratio of the retaining wall is 1:0.5, the height of the soil slope is 1.5m, the length of the retaining wall is 1m, and the supporting width of the retaining wall is 0.37m. A uniform load of 0.9m×0.5m is applied to the site where the construction slag geotextile bag is placed, and the slope support effect of the retaining wall with the reverse-packed construction slag geotechnical bag is studied.

The design diagram of the two groups of comparative model experiments in this experiment:

(1) Basic experiment: When the slope ratio is 1:0.5, the natural soil slope (referred to as working condition 1), the retaining wall of the slag geotechnical bag (referred to as working condition 2), and the length of the first geogrid are 0.9m. Figure 2 shows the model design drawings of the retaining wall under three different working conditions. In Figure 2, a, b, and c correspond to working condition 1, working condition 2, and working condition 3 in turn.

(2) In the case of the same slope ratio of 1:0.5, the influence of the different lengths of the first geogrid on the slope reinforcement effect of the reverse-packed slag geobag retaining wall in the present application is studied, namely: the first geogrid The length of the grid is 0.5m (referred to as working condition 4, as shown in Figure 3a), the length of the first geogrid is 0.9m (referred to as working condition 3, as shown in Figure 3b), and the length of the first geogrid is 1.3m (referred to as the working condition). Case 5, as shown in Figure 3c). Figure 3 shows the model design drawings of the first geogrid with different lengths of the slag-retaining slag geobag retaining wall.

1.4 Test materials

(1) Slope material

The soil behind the retaining wall is silty clay common in Sichuan, and its physical and mechanical indexes are measured by geotechnical experiments in accordance with the "Civil Experiment Regulations" (SL237-1999). The physical and mechanical indexes of the slope soil are shown below. shown in Table 1.

Table 1 Slope soil physical and mechanical indicators

Density/(g.cm^-3) Moisture content/% Cohesion/kPa Internal friction angle/(°) 1.5 15.3 26.9 25.9

(2) Construction waste geotechnical bag

The original size of the geotechnical bag is 440mm×815mm, and the geotechnical bag is scaled according to the geometric similarity ratio of 1:4, so the size of the geotechnical bag used in the model test is 110mm×204mm. The geotextile bag used in this model test is a green high-polymer green woven bag that is environmentally friendly. The ultimate tensile strength is not less than 30kN/m, and the elongation at break is less than or equal to 30%; the mesh size of the geotextile is in accordance with the design requirements. The main technical index requirements are shown in Table 2.

Table 2 Main technical indicators of geotextiles

project Technical index requirements Weft breaking strength ≥30kN/m Elongation at break ≤30% (warp and weft) CBR burst strength ≥2.4kN vertical permeability coefficient ＞1.0mm/s-1.0×10^-3mm/s door width ≥4.0m (deviation -1%)

According to the previous test results, when the construction slag is used as the filling of the geotextile bag, the strength of the construction slag geotechnical bag is the best when the content of waste concrete blocks and waste bricks is 50%. Therefore, the filling of the slag geotextile bag in this experiment is 50% concrete blocks and 50% bricks. According to the geometric similarity ratio of 1:4, the particle sizes of the waste concrete blocks and the waste bricks are scaled down, and the content of each particle size of the aggregates after the scale down remains unchanged.

The construction slag is crushed by a jaw crusher, and then the particle size is screened, and the geotechnical bag is bagged according to the filling degree of the construction slag geotechnical bag is 80%.

(4) Geogrid

The geogrid used in this test is a high-density polyethylene biaxially stretched plastic geogrid. The polyethylene biaxially stretched geogrid has high strength, low creep, strong bearing capacity, corrosion resistance, anti-aging, and large friction coefficient. Etc. Its main performance parameter requirements are shown in Table 3.

Table 3 Geogrid performance parameters

2 loading device

The model test is carried out with a 1:4 similarity ratio. According to the similarity theorem, the model should not only meet the similarity ratio, but also meet the conditions of similar loads. Therefore, the load value converted according to the similarity ratio is small. This test adopts the lever loading which is more convenient to implement. The lever loading system is composed of levers, weights, counterweights, weight plates, hinge points and load transmission rods.

The loading area is the top surface of the slope behind the geobag wall. In order to prevent the two sides of the depression in the middle of the loading plate from lifting up during the loading process, so that the force is evenly distributed, two loading steel plates are set. Its dimensions are 0.9m×0.5m×10mm, 0.3m×0.3m×20mm (length×width×thickness). To prevent the loading weight from being too heavy during loading, causing the loading device to roll over, connect the side of the loading device with steel bars to form a mesh, which is convenient for stacking heavy objects, and at the same time use expansion bolts on the side of the loading device to fix it in the ground. The method of lever loading used in this application test is to load when balancing the dead weight of the lever (the counterweight is the dead weight of the lever loading device), and the lever ratio is 1:7, as shown in Figure 4.

Load the top of the retaining wall in stages until the loading plate forms a uniform load, and measure the data every 10 minutes, including observing and recording the settlement displacement of the top of the slope and the horizontal displacement of the slope of the retaining wall until the data is stable Then proceed to the next level of loading.

3 Test content and test component layout

In this model test, the test contents include: the failure load of the slope top of the retaining wall, the settlement displacement of the slope top, the horizontal displacement of the wall surface, and the magnitude and change of the lateral earth pressure.

3.1 Ultimate load at the top of the slope

The failure load at the top of the slope refers to the use of levers to apply a uniform load on the top of the retaining wall during the test. When the applied uniform load is basically unchanged or reduced, the settlement of the top of the slope increases rapidly, and the slope is obviously connected. The uniform load on the top of the slope when the slope is damaged is called the failure load on the top of the slope.

3.2 Settlement displacement of slope top

The settlement displacement of the top of the retaining wall refers to the vertical settlement and deformation of the top of the retaining wall under the action of uniformly distributed loads on the top of the retaining wall. A dial indicator (50mm) is arranged on the load plate in the loading area of the top of the retaining wall to read the vertical settlement displacement of the top of the slope.

3.3 Horizontal displacement of the wall

The horizontal displacement of the retaining wall slope means that under the action of uniformly distributed load applied to the top of the retaining wall slope, after the soil is compacted, due to the constraints of the three sides of the model groove, the overall direction of the retaining wall slope soil is move out, so that the slope of the retaining wall is displaced horizontally. The horizontal displacement of the soil mass on the slope of the retaining wall is read by the dial indicator (50mm and 30mm range). A total of 10 dial indicators are required, and five rows of dial indicators are arranged along the height in the horizontal direction, and each row is used to measure the horizontal displacement of different slope heights. The layout positions are shown in Figure 5; among them, Figure 5(a) is Schematic diagram of the dial indicator, Figure 5(b) is the actual layout of the dial indicator.

3.4 Lateral earth pressure

Lateral earth pressure refers to the outward earth pressure generated by the soil mass under the action of uniformly distributed loads on the top of the retaining wall. The lateral earth pressure measured in this test is obtained by burying a micro-strain earth pressure cell at 10 cm from the edge of the slope soil, and connecting the static resistance strain gauge to measure the strain value, which is converted by the calibration parameters. Earth pressure calculation formula: Ρ=με*K In the formula: P is the pressure value (k Pa), με is the strain variable, and K is the rate coefficient.

In order to reduce the experimental error, a layer of fine silty clay was laid on the location where the earth pressure cell was laid. When burying the earth pressure box, it is necessary to bury the earth pressure box vertically, and measure the lateral earth pressure at the corresponding position of the retaining wall. A total of 12 earth pressure cells of 100kPa are required for this test. The layout position is shown in Figure 6, and the section layout is shown in Figure 7.

3.5 Geogrid strain test

The strain of the geogrid refers to the local deformation of the geogrid under the action of a uniform load applied to the top of the retaining wall slope. To test the strain of the geogrid, the strain gauge is arranged along the length of the first geogrid, and the strain value is measured by connecting the static resistance strain gauge. In this model test, five strain gauges were arranged at equal intervals along the middle part of the length of the first geogrid in the reinforced section of the geogrid at the height of 60cm and 90cm of the retaining wall. The layout of the strain gauge is shown in Figure 8.

In this embodiment, the steps of pasting and wiring the strain gauge are as follows:

(1) On the cut geogrid, mark the corresponding position where the strain gauge needs to be pasted;

(2) Grinding the geogrid at the mark with the sandpaper at 45° for several times, so that the strain gauge can be better fixed on the geogrid;

(3) When pasting the strain gauge with 502 glue, cover the strain gauge with a piece of polyethylene plastic film and press it to drive away the air bubbles in the 502 glue, so that the geogrid and the strain gauge can fit better and ensure the force of the geogrid The situation can be better transmitted to the stress gauge inspection;

(4) After attaching the strain gauge, use a multimeter to check whether the strain gauge is broken and whether the fit meets the requirements;

(5) After the strain gage is firmly attached, use a multimeter to check whether it is a path after connecting the strain gage, and attach a label with the name of the measuring point to the end of the wire.

4 Model test process

4.1 Model slot erection

In order to observe the deformation and damage changes of the retaining wall slope during the test, a transparent tempered glass was installed on one side of the model groove. Although tempered glass has high compressive strength, it is fragile; therefore, when setting up the model groove, use rubber to fit the contact surface between the I-beam and the tempered glass, so that the tempered glass is evenly stressed. In order to reduce the influence of the sidewall of the model groove on the model test of the retaining wall, the sidewall of the retaining wall should be cleaned, smeared with a layer of lubricating silicone grease, and then pasted with a layer of plastic film.

4.2 Model making of retaining wall

According to the design scheme of the model test, the cutting length of the geogrid is determined according to the length of the first geogrid, the length of the turn-up section and the fixed section of the geogrid, and the cutting width of the geogrid is determined according to the width of the model. Before starting, cut the geogrid to the corresponding size, and paste and wire the strain gauge in the corresponding layout. The cutting lengths of geogrids with three different first geogrid lengths are shown in Table 4.

Table 4 Geogrid cutting lengths with different first geogrid lengths

The production process is as follows.

(1) First, a rammed soil body with a thickness of 0.1 m (that is, the bottom layer of the present application) needs to be laid at the bottom of the model groove, which is used as the cushion for the model test.

(2) Laying geogrids and construction slag geotextiles: Lay the geogrids in the filling, and reserve the length of the geogrids in the turn-up section and the fixed section to ensure the reinforcement of the geogrids (that is, the The length of the first geogrid in the application); the geogrid must be laid horizontally and perpendicular to the wall. Place the construction slag geotechnical bag on the slope of the retaining wall soil (the upper and lower layers of geotechnical bags are staggered), and build a 30cm-high construction slag geotechnical bag; That is, the second geogrid of this application) wraps the built-up slag geotechnical bag (that is, the second geotechnical bag in this application), and then uses U-shaped nails to fix the geogrid of the fixed section (that is, the geotechnical bag of this application). The third geogrid) is anchored into the rammed soil; the soil is filled on the first geogrid to form a filled soil to form a reinforced section; finally, the third geobag is vertically superimposed on the third geogrid On the geogrid, a fixed section is formed. The laying of the geogrid is shown in Fig. 9 (wherein, Fig. 9(a) is the laying diagram of the first geogrid, and Fig. 9(b) is the reverse wrapping diagram of the second geogrid), and the placement of the third geogrid is shown in Fig. 10 (wherein, FIG. 10a is a top view, and FIG. 10b is a front view).

(3) Filling and compaction: The retaining wall in this model test is 1.5m high, and the method of layered backfill and layered compacted soil is used for filling and compaction. In order to make the density of the soil uniform and reach 1.5g/cm ³ , the test was carried out in layers with a thickness of 15 cm for each layer of soil, and a total of ten times of filling and tamping were performed.

Calculate the weight of silty clay required for each layer of backfill according to the design and specification requirements and the known density of the silty clay used in the test. When backfilling in layers, backfill is carried out according to the weight of the required backfill soil for each layer, and then compacted to the corresponding height. When tamped to the bottom level of the upper layer of retaining wall components, lay the upper layer of retaining wall components. When compacting the soil, start from the end of the geogrid first, and the backfill needs to be fully compacted so that the compaction degree of the backfill reaches the corresponding height. At the same time, in the process of filling the soil and laying the geogrid, it is also necessary to arrange the earth pressure cells in the corresponding positions of the soil according to the earth pressure cell layout diagram.

4.3 Loading board installation

After the model of the retaining wall with the anti-construction slag geobag is completed, in order to make the retaining wall evenly stressed, the soil at the top of the retaining wall needs to be compacted and leveled. A 0.9m×0.5m loaded steel plate is placed on the top surface of the slope behind the retaining wall of the slag geotechnical bag close to the top of the slope, connected by a combination of dowel rods, and a lever loading device is used externally to apply a uniform load.

Generally, the connection force transmission between the traditional load plate and the lever loading device is set to be fixed, but when the slope body settles, the lever rotates downward and tilts, so that the force exerted by the lever on the slope top of the retaining wall is no longer vertically downward. In this paper, the lever loading system uses spherical hinges to connect the lever and the load transfer rod. A steel ball with a diameter of 30mm is welded on the load transfer rod, and then the upper half of the steel ball is embedded in the groove of the thin-walled barrel, and the groove is connected with a piece of steel ball. The steel plate with a thickness of 20mm is welded and fixed on the lever, so as to ensure that the force exerted by the lever is vertically downward, as shown in Figure 11.

4.4 Measuring instrument connection

The measuring part of the strain gauge is fixed at the tensile place of the geogrid, and the connection between the strain gauge and the wire is connected by electric soldering. After all fixing is completed, use a multimeter to check whether the strain gauge is working normally, and the resistance shows 120Ω, which means it is normal. The strain gauge is connected to the strain gauge by the 1/4 bridge method, in which the red wire is connected to the +Eg terminal, and the black wire is connected to the Vi`` terminal. Each unit is connected to a temperature compensation film, the red wire of the temperature compensation film is connected to the +Eg terminal, and the black wire is connected to the Comp terminal.

Because the earth pressure cell has its own temperature compensation, the full bridge method is used to connect the ^TST3826F -L static resistance strain gauge in this test. Vi ^- end. Before connecting the strain gauge, it is necessary to use a multimeter to check whether the earth pressure cell is working properly. The resistance display of 350Ω means it is normal.

4.5 Testing

Enter the test system of the TST3826F-L static resistance strain gauge, and adjust the channel parameters of each measuring point according to the corresponding parameters of the earth pressure cell and strain. The connection mode of the strain gauge is set to 1/4 bridge with compensation, and the resistance value is 120Ω; the connection mode of the earth pressure cell is set to be full bridge, and the resistance value is 350Ω. First balance the system, then clear it, create a corresponding text file, and then start the test.

Staged loading via levers. For each loading level, observe the vertical settlement displacement of the top of the slope and the change of the horizontal displacement of the slope body, and read the dial indicator, the earth pressure cell and the strain reading of the geogrid every 10 minutes. After the data is stable, proceed to the next level of loading until the The test ends when the retaining wall fails.

(2) Model test data processing and result analysis

5. Comparative analysis of supporting effect of basic experiments

5.1 Analysis of settlement and displacement of slope top

Natural soil slope (Condition 1), under the action of the uniformly distributed load vertically downward from the top of the slope, when the load is loaded to 14.28kPa, the natural soil slope surface is overturned, and the final settlement displacement of the top of the slope is 21.47mm . Figure 12 shows the test photos of the natural soil slope before and after loading. Among them, Fig. 12(a) is a test diagram before loading, and Fig. 12(b) is a test diagram after loading.

At the beginning of the loading stage, the soil is gradually compacted and the settlement displacement of the top of the slope is relatively large under the action of the uniformly distributed load vertically downward from the top of the slope. Increase, because the soil has been compacted, the increase in the settlement displacement of the top of the slope decreases. When loaded to 28.56kPa, the final settlement displacement of the top of the retaining wall with the slag geotextile bag is 39.23mm. Figure 13 shows the test photos of the retaining wall before and after the construction slag geobag retaining wall is loaded. Among them, Fig. 13(a) is the test picture before loading, and Fig. 13(b) is the test picture after loading.

The first geogrid length is 0.9m for the reverse-packed slag geobag retaining wall (Condition 3), the settlement displacement of the top of the retaining wall during the loading process and the loading result of the slag geobag retaining wall resemblance. When the failure load at the top of the slope is 44.43kPa, the settlement displacement of the top of the retaining wall is 47.59mm, as shown in Figure 3; among them, Figure 13(a) is the test picture before loading, and Figure 13(b) is after loading. Subsidence deformation diagram.

Figure 15 shows the relationship between the uniformly distributed load on the top of the retaining wall and the settlement displacement of the top of the retaining wall under three different working conditions (Condition 1, Condition 2, and Condition 3). From Fig. 15, it can be concluded that in the initial stage of loading, the soil is gradually compacted under the action of the load, and the settlement displacement of the slope top under the three different working conditions changes greatly; However, the soil has been compacted, and the range of settlement and displacement of the top of the retaining wall is reduced. Compared with the natural soil slope and the construction slag geobag retaining wall, the uniformly distributed load on the slope top of the reverse-packed construction slag geotechnical bag retaining wall structure increases; and under the same uniform load, the slope top Settlement displacement is reduced.

5.2 Analysis of the horizontal displacement of the wall

The variation law of the horizontal displacement along the height of the retaining wall along the middle and edge of the slope wall of the natural soil slope (Condition 1) is shown in Figure 16. Among them, Fig. 16(a) is the horizontal displacement diagram in the middle of the wall in working condition 1, and Fig. 16(b) is the horizontal displacement graph on the edge of the wall in working condition 1. Under the action of the uniformly distributed load on the slope top, since the slope surface of the natural soil slope does not have any reinforcement measures, with the continuous increase of the uniformly distributed load on the slope top, the horizontal displacement of the natural soil slope slope increases with the height of the retaining wall. The direction shows a changing law of first increasing and then decreasing.

Figure 17 shows the variation law of the horizontal displacement along the height of the retaining wall along the middle and edge of the slope wall of the slag geobag retaining wall (Condition 2). Among them, Fig. 17(a) is the horizontal displacement diagram in the middle of the wall in working condition 2, and Fig. 17(b) is the horizontal displacement diagram on the edge of the wall in working condition 2. At the beginning of the loading stage, the horizontal displacement of the retaining wall is small due to the restriction of the soil slope by the slag geotechnical bag. With the continuous increase of the uniformly distributed load at the top of the slope, the horizontal displacement of the overall wall surface of the retaining wall made of construction slag geotechnical bags gradually increases.

The horizontal displacement of the wall surface of the slag geotechnical bag retaining wall is distributed in a drum shape, and it first increases and then decreases with the height of the retaining wall. 2/3. Since the sidewall of the model groove has a certain restraint effect on its retaining wall, the horizontal displacement on the edge of the retaining wall is somewhat smaller than the horizontal displacement in the middle of the wall, but it also presents a similar regular distribution.

The variation law of the horizontal displacement along the height of the retaining wall in the middle and on the edge of the side slope wall of the 0.9m-long reverse-packed slag geobag retaining wall (Condition 3), as shown in Figure 18 shown. Among them, Fig. 18(a) is the horizontal displacement diagram in the middle of the wall in working condition 3, and Fig. 18(b) is the horizontal displacement diagram on the edge of the wall in working condition 3. At the beginning of the loading stage, under the reinforcement of the geogrid construction slag geobag retaining wall, the geobag constrains the soil slope and the geogrid has a certain interlocking effect on the soil. and occlusal effect, so that the horizontal displacement of the wall surface of the reverse-packed slag geotechnical bag retaining wall is small; with the continuous increase of the uniform load on the top of the slope, the horizontal displacement of the overall wall surface of the retaining wall gradually increases. big. The change rule of the horizontal displacement of the first geogrid 0.9m length of the slag geotechnical bag retaining wall is also in a drum-shaped distribution, which is similar to the change rule of the large slag geotechnical retaining wall.

5.3 Lateral earth pressure analysis

Figure 19 shows the lateral earth pressure distribution behind the wall of the slag geobag retaining wall (Condition 2) and the 0.9m first geogrid length of the turn-back type slag geobag retaining wall (Condition 3) Graph. It can be seen from the figure that the lateral earth pressure behind the retaining wall is not triangularly distributed, and the lateral earth pressure is the largest at about 1/3 to 2/3 of the wall height; The lateral earth pressure on the edge of the retaining wall is relatively reduced. Combined with the analysis of the horizontal displacement of the retaining wall, the maximum lateral earth pressure generated at the same height of the retaining wall and the maximum horizontal displacement of the wall both appear at about 1/3 to 2/3 of the retaining wall height. ; The greater the lateral earth pressure, the greater the horizontal displacement of the retaining wall.

In order to better analyze the reinforcement effect of the retaining wall slope in working conditions 1, 2 and 3, the uniformly distributed loads on the top of the slope under the three different working conditions and the slope of the retaining wall under the same uniform load (12.7kPa) were analyzed. The top settlement displacement and the maximum horizontal displacement of the wall are listed in the table, as shown in Table 5.

Table 5 Comparative analysis of retaining wall slopes in working conditions 1, 2, and 3

name Condition 1 Condition 2 Condition 3 Top failure load/kPa 14.28 28.56 44.43 Slope top settlement displacement (uniform load is 12.7kPa)/mm 18.87 16.94 13.37 The maximum horizontal displacement of the wall (uniform load is 12.7kPa)/mm 9.36 3.56 2.36

It can be seen from Table 5 that:

(1) Comparing working conditions 1 to 3, the top failure load of working condition 1 is 14.28kPa, the top failure load of working condition 2 is 28.56kPa, and the failure load of working condition 3 is 44.43kPa; The failure load at the top of the slope is 211.1% higher than that of case 1 and 55.6% higher than that of case 2.

(2) When the uniformly distributed load on the slope top is 12.7kPa, the settlement displacement of the slope top in working condition 1 is 18.87 mm, that of working condition 2 is 16.94 mm, and that of working condition 3 is 13.37 mm; The top settlement displacement of working condition 3 is 29.15% lower than that of working condition 1, and 21.07% lower than that of working condition 2.

(3) When the uniformly distributed load on the slope top is 12.7kPa, the maximum horizontal displacement of the wall in working condition 1 is 9.36 mm, the maximum horizontal displacement of the wall in working condition 2 is 3.56 mm, and the maximum horizontal displacement of the wall in working condition 3 is 2.36mm; the maximum horizontal displacement of the wall in working condition 3 is 74.79% lower than that in working condition 1, and 33.71% lower than that in working condition 2.

6 Comparative analysis of slope support effects with different first geogrid lengths

6.1 Analysis of settlement and displacement of slope top

When the first geogrid length is 0.5m for the slag-retaining geobag retaining wall (Condition 4), when the top failure load of the retaining wall is 31.73kPa during the loading process, the top of the retaining wall settles The displacement is 43.77mm. The first geogrid length is 1.3m for the reverse-packed slag geobag retaining wall (Condition 5), when the top failure load of the retaining wall is 50.77kPa during the loading process, the top of the retaining wall settles The displacement is 49.85mm. The photos of the test results of working conditions 4 and 5 are shown in Figure 20. Among them, Fig. 20(a) is the top crack diagram of working condition 4, Fig. 20(b) is the slope body crack graph of working condition 4, Fig. 20(c) is the top settlement deformation diagram of working condition 5, Fig. 20 (d) is the slope crack map of working condition 5.

The relationship between the uniform load on the top of the slope and the settlement displacement of the top of the slope for three different first geogrid lengths of 0.5m, 0.9m, and 1.3m for retaining walls (Condition 4, Condition 3, and Condition 5), as shown in the figure 21 shown. From Figure 21, it can be concluded that the longer the length of the first geogrid of the reverse-packed slag geotechnical bag retaining wall, the greater the ultimate load at the top of the retaining wall. Under the same load on the top of the slope, the longer the first geogrid length of the retaining wall, the smaller the settlement displacement of the top of the slope; The settlement and displacement of the top of the retaining wall with the first geogrid length of 0.5m changed greatly, but the top settlement of the retaining wall with the first geogrid length of 0.9m and the first geogrid length of 1.3m The displacement changes are similar.

The relationship between the uniform load on the top of the slope and the settlement displacement of the top of the slope for three different first geogrid lengths of 0.5m, 0.9m, and 1.3m for retaining walls (Condition 4, Condition 3, and Condition 5), as shown in the figure 21 shown. From Figure 21, it can be concluded that the longer the length of the first geogrid of the reverse-packed slag geotechnical bag retaining wall, the greater the ultimate load at the top of the retaining wall. Under the same load on the top of the slope, the longer the first geogrid length of the retaining wall, the smaller the settlement displacement of the top of the slope; The settlement and displacement of the top of the retaining wall with the first geogrid length of 0.5m changed greatly, but the top settlement of the retaining wall with the first geogrid length of 0.9m and the first geogrid length of 1.3m The displacement changes are similar.

6.2 Analysis of the horizontal displacement of the wall

Figure 22 shows the variation law of the horizontal displacement along the height of the retaining wall in the middle and on the edge of the slope wall in working conditions 4 and 5. Figure 22(a) is the horizontal displacement diagram in the middle of the wall in working condition 4, and Figure 22(b) is the horizontal displacement diagram on the side of the wall in working condition 4.

Figure 22(c) is the horizontal displacement diagram in the middle of the wall in working condition 5, and Figure 22(d) is the horizontal displacement diagram on the side of the wall in working condition 5. It can be seen from the figure that the horizontal displacement of the wall surface of the reverse-packed slag geobag retaining wall with different lengths of the first geogrid is consistent. With the height of the retaining wall increasing first and then decreasing, the curves are all drum-shaped , the maximum horizontal displacement of the wall of the retaining wall is about 1/3 to 2/3 of the height of the retaining wall. Since the sidewall of the model groove has a certain restraint effect on the retaining wall, the horizontal displacement on the edge of the retaining wall in the figure is relatively reduced, but it also shows a similar variation law. Under the same uniformly distributed load, the longer the length of the first geogrid, the smaller the horizontal displacement of the wall surface of the turn-up slag geobag retaining wall.

6.3 Lateral earth pressure analysis

Fig. 23 is a distribution diagram of the lateral earth pressure behind the wall of the reverse-packed slag geobag retaining wall with different lengths of the first geogrid. It can be seen from the figure that the lateral earth pressure of the wall thickness of the reverse-packed slag geobag retaining wall first increases with the height of the retaining wall, and the lateral earth pressure is the largest at a height of 50cm from the wall, and then increases with the height of the retaining wall. height gradually decreases. Combined with the analysis of the horizontal displacement of the wall surface of the retaining wall with the reverse-packed slag geotextile, the same horizontal displacement of the wall surface occurs at the same height of the retaining wall, and the longer the length of the first geogrid, the corresponding The greater the rear lateral earth pressure.

6.4 Geogrid strain analysis

In the model test, the strain of the geogrid in the turn-back reinforced retaining wall was measured in two layers; the strain of the geogrid under each level of load was recorded during the test, so as to observe and analyze the interior of the retaining wall Variation of geogrid strain.

Figure 24 is a graph showing the variation of the geogrid strain with the load of the first geogrid length of 0.5m for the turn-up slag geobag retaining wall (Condition 4). Among them, Fig. 24(a) is the strain map of the first layer measuring point of working condition 4, and Fig. 24(b) is the second layer measuring point strain map of working condition 4. It can be seen from the figure that the general law of the strain of the two-layer geogrid increases with the increase of the uniformly distributed load on the top of the slope, but the variation law of the strain of each measured geogrid is not the same. Due to the short length of reinforcement, the lateral displacement of the slope of the retaining wall is large, and the measuring points 1-10 are all located under the loading plate and at the slope of the retaining wall, so the strain changes of each measuring point are not much different. . Among them, when the uniformly distributed load at the top of the slope reaches 31.73kPa, the largest strain value in the first layer measuring point is 1252.73με of No. 1 measuring point, and the largest strain value in the second layer measuring point is No. 6 measuring point 1356.87με .

Figure 25 is a graph showing the variation of the geogrid strain with the load of the first geogrid length of 0.9m for the turn-up slag geobag retaining wall (Condition 3). Among them, Fig. 25(a) is the strain map of the first layer measuring point of working condition 3, and Fig. 25(b) is the second layer measuring point strain map of working condition 3. It can be seen from the figure that the strain values of measuring points 2, 3, 6, 7, and 8 located below the loading plate in case 3 change more obviously with the increase of the load. Among them, when the uniformly distributed load on the top of the slope reaches 44.43kPa, the largest strain value in the first layer measuring point is 1812.47με of No. 2 measuring point, and the largest strain value in the second layer measuring point is No. 8 measuring point 2169.87με .

Fig. 26 is a graph showing the variation of geogrid strain with load for a 1.3m reinforced slag-backed geobag retaining wall (Condition 5). Among them, Fig. 26(a) is the strain map of the first layer measuring point in working condition 5, and Fig. 26(b) is the second layer measuring point strain graph in working condition 5. It can be seen from the figure that the strain values of No. 3, 4, 8, and 9 measuring points located below and at the edge of the loading plate in case 5 change more obviously with the increase of the load, while those inside the retaining wall and the distance from the loading plate are more obvious. The strain values of the distant measuring points 1, 2 and 6 change little with the increase of the load. Among them, when the uniform load on the top of the slope reaches 50.77kPa, the maximum strain value in the first layer measuring point is 2536.25με of the No. 4 measuring point, and the largest strain value in the second layer measuring point is the No. 8 measuring point 2921.64 με .

Figure 24, Figure 25, and Figure 26 are combined to analyze the geogrid strain of the reverse-packed slag geobag retaining wall with different lengths of the first geogrid. The strain value of the geogrid increases with increasing load; while the strain value of the measuring point inside the soil body which is far from the loading plate and close to the retaining wall surface increases with the load, and the strain of the geogrid is smaller. Under the same uniform load on the top of the slope, the longer the length of the first geogrid is, the geogrid strain corresponding to the measuring point decreases relatively.

In order to better analyze the influence of different lengths of the first geogrid on the reinforcement effect of the retaining wall slope, the slope tops of working conditions 3, 4 and 5 are subjected to the failure load and the same uniform load (31.73kPa, which is the same as that of working condition 4). The slope top settlement displacement, the maximum horizontal displacement of the wall surface, and the maximum strain value of the geogrid under the slope top ultimate failure load) of the retaining wall are arranged in the table, as shown in Table 6.

Table 6 Comparative analysis of retaining wall slopes in working conditions 3, 4, and 5

It can be seen from Table 6 that:

(1) Comparing working conditions 3 to 5, the top failure load of working condition 4 is 31.73kPa, that of working condition 3 is 44.43kPa, and that of working condition 5 is 50.77kPa; The failure load at the top of the slope is 60% higher than that of case 4 and 14.27% higher than that of case 3.

(2) When the uniformly distributed load on the slope top is 31.73kPa, the settlement displacement of the slope top in working condition 4 is 43.77 mm, that of working condition 3 is 36.58 mm, and that of working condition 5 is 32.76 mm; The top settlement displacement of working condition 5 is 25.1% lower than that of working condition 4, and 10.44% lower than that of working condition 3.

(3) When the uniformly distributed load on the slope top is 31.73kPa, the maximum horizontal displacement of the wall in working condition 4 is 16.87 mm, the maximum horizontal displacement of the wall in working condition 3 is 14.21 mm, and the maximum horizontal displacement of the wall in working condition 5 is The maximum horizontal displacement of the wall in working condition 5 is 42.03% lower than that in working condition 4, and 31.18% lower than that in working condition 3.

(4) When the uniformly distributed load on the slope top is 31.73kPa, the maximum strain of the geogrid under working condition 4 is 1356.87, the maximum strain of the geogrid under working condition 3 is 1125.89, and the maximum strain of the geogrid under working condition 5 is 987.56; The maximum strain of the geogrid in working condition 5 is 27.22% lower than that in working condition 4, and 12.87% lower than that in working condition 3.

7 can be known based on the above-mentioned experimental data.

(1) Compared with the natural soil slope and the construction slag geobag retaining wall, the failure load of the top of the slope is increased by 211.1% and 55.6% respectively. The failure load of the top of the slope top of the reverse-packed slag geobag retaining wall increases significantly, and the settlement displacement of the top of the slope decreases significantly under the same uniform load. Therefore, the slope reinforcement effect of the reverse-packed slag geobag retaining wall is obvious.

(2) The horizontal displacement of the wall surface of the reverse-packed slag geobag retaining wall is distributed in a drum shape, which is similar to the distribution law of the horizontal displacement of the wall surface of the slag geobag retaining wall. Under the same uniform load, the maximum horizontal displacement of the wall in case 3 is 34.56% lower than that in case 1, and 18.64% lower than that in case 2; The horizontal displacement of the surface is smaller than the horizontal displacement of the wall surface of the natural soil slope and the construction slag geobag retaining wall. This shows that the overall performance of the retaining wall structure with the turn-up slag geobag is better, and it can effectively restrain the lateral deformation of the retaining wall.

(3) The lateral earth pressure behind the wall of the back-packed slag geobag retaining wall is not a triangular distribution, but a drum-shaped distribution, and the lateral earth pressure is the largest at about 1/3 to 2/3 of the wall height; Due to the constraint of the sidewall of the model groove, the lateral earth pressure on the edge of the retaining wall is relatively reduced.

(4) The longer the first geogrid is, the greater the failure load of the top of the slope of the turn-up slag geobag retaining wall; under the same uniform load, the longer the first geogrid, the settlement of the top of the slope is The smaller the displacement, the smaller the horizontal displacement of the retaining wall, and the smaller the strain value of the geogrid. Therefore, the longer the first geogrid of the turn-up slag geobag retaining wall is, the more obvious the slope reinforcement effect is.

The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims (10)

1. The reverse-wrapping type slag-building earth bag retaining wall is characterized by comprising a bottom layer and a protection unit arranged on the bottom layer, wherein the protection unit consists of N retaining wall components, and N is more than or equal to 1;

the retaining wall component is formed by sequentially connecting a reinforcement section, a reverse-wrapping section and a fixing section;

the reinforced section comprises a first geogrid and a filling soil body which are paved, and the filling soil body is positioned on the first geogrid;

the reverse wrapping section comprises at least one second geogrid and a second geotextile bag, the second geotextile bags are overlapped together, and the second geogrid is wrapped on the outer side of each second geotextile bag and connects the second geotextile bags into a whole;

the fixing section comprises a third geogrid and a third geotextile bag which are laid flatly, the third geotextile bag is at least one and is sequentially overlapped together along the vertical direction, and the geotextile bag is positioned on the third geogrid;

one side of the fixed section, which is far away from the reinforced section, is obliquely arranged relative to the vertical direction, and the included angle between the side surface of the fixed section, which is far away from the reinforced section, and the horizontal plane is 2 ~ 75 degrees;

the first geogrid, the second geogrid and the third geogrid are sequentially connected;

and the first geotextile bag and the second geotextile bag are respectively filled with building slag.

2. A retaining wall according to claim 1, characterised in that the side of the anchoring section remote from the reinforced section is at an angle of 15 ~ 35 ° to the horizontal.

3. A retaining wall according to claim 1 wherein the side of the retaining wall assembly remote from the reinforced section is larger at the bottom and smaller at the top.

4. A retaining wall according to claim 1, characterized in that the upper end point of the side of the retaining section remote from the reinforced section is located between the lower end point of the side of the retaining section remote from the reinforced section and the turn-up section.

5. A retaining wall according to claim 1, characterized in that the retaining unit is formed by stacking at least two retaining wall components in a vertical direction;

recording the retaining wall assemblies as a first retaining wall assembly structure and an … … Nth retaining wall assembly in sequence along the direction from bottom to top, wherein N is more than or equal to 2;

the first geogrid of the first retaining wall component is paved on the bottom layer, and the first geogrid of the Nth retaining wall component is paved on the filling soil body of the (N-1) th retaining wall component;

one side of the upper fixing section of the protection unit is in a shape of being large at the bottom and small at the top.

6. A retaining wall according to claim 1, characterised in that the reinforced section is located on the side close to the slope and the anchoring section is located on the side remote from the slope.

7. A retaining wall according to claim 1, characterized in that the turn-up section is formed by sequentially stacking two to six layers of second geotextile bags; the fixed section is formed by stacking two to six layers of third geotextile bags along the vertical direction.

8. A construction method of a reverse-wrapping type slag building geotextile bag retaining wall is characterized by comprising the following steps:

(1) the bottom layer of the position to be protected is arranged flatly;

(2) determining the lengths of the first geogrid, the second geogrid and the third geogrid according to design requirements on the basis of the finished and flat bottom layer, and selecting the geogrids with corresponding lengths to be laid on the surface of the base layer; filling soil on the first geogrid to form a filling soil body to form a reinforced section; stacking the second geotextile bags together to form a second stacked body, and wrapping a second geogrid on the outer surface of the second stacked body to form a reverse wrapping section; superposing a third geotextile bag on a third geogrid along the vertical direction to form a fixed section; after the reinforced section, the reverse-wrapped section and the fixed section are constructed, a first retaining wall component is formed;

(3) repeating the step (2) on the basis of the upper surface of the first retaining wall component to form a second retaining wall component; repeating the steps until an Nth retaining wall component is formed.

9. Use of the reverse-wrapped geotextile bag retaining wall as claimed in any one of claims 1 ~ 7.

10. The use according to claim 9, characterized in that the aforementioned reverse-wrapped geotextile bag retaining wall is used in slope protection.

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