Shallow roadbed chambering splitting grouting structure enhancement layout

Abstract

The utility model discloses a shallow roadbed chambering splitting grouting structure enhanced layout, which is characterized in that a plurality of drill holes are divided into a plurality of rows, each row of drill holes are in one-to-one correspondence, the plurality of drill holes form a plurality of columns, the drill holes are drilled into an old pavement layer and an old roadbed layer, and the roadbed layer is filled with soil from the drill holes for chambering. According to the technical scheme, the high-strength thick piles are formed in the soil body through hole position layout, the thick piles and the soil body are formed into a whole through splitting and filling of the grout to the soil body in cooperation with a corresponding grouting mode, new powerful support is formed for an old pavement structure, and the bending and tensile life of a base layer is remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The utility model relates to road engineering technical field, concretely relates to a shallow roadbed reaming split grouting structure enhancement layout. BACKGROUND

[0002] With the development of social economy and planning adjustment, the contradiction between the thin early-built highway pavement structure and the dramatic increase of traffic load after upgrading often occurs. Because of the large cost, long construction period and great traffic interference of excavation reinforcement, the non-excavation reinforcement scheme is the trend.

[0003] During the large-scale development of infrastructure in China, soil grouting technology and soft soil replacement enhancement have been very mature. Steel flower pipe, sleeve valve pipe and other grouting reinforcement processes have been developed. In addition, soil replacement processes such as jet grouting pile and powder jetting pile have been developed. Materials such as cement (including micro-expansion), fly ash-cement and geopolymer have also been developed, solving the problem of foundation bearing capacity of structures such as bridges and buildings, but they are not suitable for disposing shallow soil.

[0004] In addition, grouting reinforcement technology is also commonly used for repairing damaged pavement structure. When dealing with cracking base and base bottom void, cement mortar and other materials are injected by pressure to re-cement the cracked base and fill the void between the soil foundation and the base formed by the subsidence of the soil foundation under long-term traffic, effectively restoring the bearing capacity of the pavement, but it cannot further enhance the bearing capacity of the pavement structure.

[0005] Because of reconstruction and expansion or traffic planning adjustment, some roads that originally did not bear traffic or had only small traffic volume after reconstruction have to bear significantly increased traffic volume. This type of road faces unprecedented challenges in using non-excavation reinforcement technology. At present, there is a lack of shallow roadbed non-excavation structure enhancement hole layout structure to improve the flexural life of the base. UTILITY MODEL CONTENTS

[0006] In view of the defects in the prior art, the utility model provides a shallow roadbed reaming split grouting structure enhancement layout. In this technical solution, the hole layout is combined with the corresponding grouting method to significantly improve the flexural life of the base.

[0007] A shallow roadbed reaming split grouting structure enhancement layout, a plurality of drill holes are divided into multiple rows, each row of drill holes corresponds one-to-one, and the plurality of drill holes form multiple columns. The drill holes are drilled into the old pavement layer and the old road base, and reaming is performed in the soil roadbed layer from the drill holes. During grouting, the grouting gun is locked to the base bottom position, split grouting is performed on the reaming, and a coarse pile support structure that is tightly combined with the soil body is formed by the split and filling effect of high-pressure slurry in the lower part of the pavement structure.

[0008] Preferably, the diameter of the drill hole is 110-200mm, and the reaming hole diameter is 250-500mm.

[0009] Preferably, the distance between the centers of adjacent boreholes in a row of boreholes is 100-150cm.

[0010] Preferably, the distance between the centers of adjacent drill holes is 35-130cm.

[0011] The beneficial effects of this utility model are reflected in the following: By using a specific hole layout, setting the distance between holes, the diameter of the holes, and the diameter of the enlarged holes, and in conjunction with a specific grouting method, the bending life of the base layer can be significantly improved, meeting the requirements for bending life, while also meeting the construction requirements for construction space and reducing construction costs. Attached Figure Description

[0012] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0013] Figure 1 This is a schematic diagram of the borehole distribution in this utility model;

[0014] Figure 2 This is a side cross-sectional view of drilling and reaming in this utility model.

[0015] In the attached diagram, 1-steel pipe, 2-auxiliary connecting pipe, 3-grouting hole. Detailed Implementation

[0016] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of protection of the present invention.

[0017] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this utility model pertains.

[0018] Example 1

[0019] like Figures 1-2 As shown in the figure, this embodiment provides a shallow subgrade borehole enlargement and splitting grouting structure reinforcement layout. Several boreholes are divided into multiple rows, with each row of boreholes corresponding to one another. Several boreholes form multiple columns. The boreholes are driven into the old pavement layer and the old subgrade layer, and the boreholes are enlarged from the boreholes into the fill subgrade layer.

[0020] When grouting, the grouting gun is locked to the position at the bottom of the base layer, and the split grouting is carried out on the hole expansion, and through the splitting and filling of high-pressure slurry, a coarse pile support structure closely combined with the soil is formed at the lower part of the road surface structure.

[0021] The diameter of the drill hole in the embodiment is 110-200mm, and the diameter of the hole expansion is 250-500mm.

[0022] The diameter of the drill hole in the embodiment is 170mm, and the diameter of the hole expansion is 300mm.

[0023] The distance between the hole centers of adjacent drill holes in a row of drill holes in the embodiment is 100-150cm.

[0024] The distance between the hole centers of adjacent rows of drill holes in the embodiment is 35-130cm.

[0025] In the embodiment, by setting the distance between the drill holes, the diameter of the drill hole, and the diameter of the hole expansion through a specific hole layout form, and cooperating with a specific grouting method, the bending and tensile life of the base layer can be significantly improved to meet the bending and tensile life requirements, while meeting the construction space construction requirements and reducing the construction cost.

[0026] Specifically as follows:

[0027] The direct split grouting method is used for hole expansion:

[0028] The drill holes are divided into multiple rows, and each row of drill holes corresponds one-to-one, and the drill holes form multiple columns.

[0029] (1) Insert a steel flower pipe 1 (Ф65-85mm) in the hole expansion, the bottom of the steel flower pipe 1 is closed, the top of the steel flower pipe 1 is connected with an auxiliary connecting pipe 2, the auxiliary connecting pipe 2 is located in the drill hole, the side wall and the bottom wall of the steel flower pipe 1 are provided with grouting small holes 3 (Ф6-8mm), the grouting small holes 3 are sealed with adhesive tape or gel, and the steel flower pipe 1 is positioned in the center of the hole expansion by a support;

[0030] (2) One-time grouting, one-time grouting is pipe outer grouting, a Φ22mm PVC pipe is inserted into the hole expansion, and cement slurry (water-cement ratio 60-100%) is injected until the cement slurry fills the entire space outside the steel flower pipe, and after waiting for 6-10 hours, it is observed that the initial setting of the grouting cement is completed;

[0031] (3) In the steel tube, insert small pipe diameter grouting pipe (Ф60-70mm), and pressurize the pipe, open the secondary split grouting (water-cement ratio 40-60%), secondary split grouting is steel tube grouting, secondary grouting is carried out in three stages, the first stage is grouting at 20cm above the hole bottom, the second stage is grouting at 40cm above the hole bottom, and the third stage is grouting at 60cm above the hole bottom, continuously increase the pressure until the cement grout bursts out by splitting (splitting pressure is generally 4-6MPa), after splitting, maintain the pressure at 1-2MPa for 2-4 minutes.

[0032] The interval time between the first grouting and the secondary split grouting is preferably 8-10 hours.

[0033] 1. Traffic volume accounting for the bending fatigue life

[0034] 1.1 Old pavement overlay

[0035] This project is located in Guangdong Province, which belongs to expressway, the starting pile number is K3534+000, and the ending pile number is K3594+896. The design service life is 15.0 years. According to the traffic volume OD investigation and analysis, the large passenger car and truck traffic volume is 4224 vehicles / day (small truck 2-axle 6-wheel 30% count), the traffic volume annual growth rate is 2.8%, the direction coefficient is 55.0%, and the lane coefficient is 78.0%. According to the traffic history data, it is determined that the designed road belongs to TTC4 type, and the vehicle type distribution coefficient is shown in Table 1.1-1.

[0036] Table 1.1-1 Vehicle type distribution coefficient

[0037] Vehicle type Class 2 Class 3 Class 4 Class 5 Class 6 Class 7 Class 8 Class 9 Class 10 Class 11 Vehicle type distribution coefficient (%) 28.9 43.9 5.5 0.0 9.4 2.0 4.6 3.4 2.3 0.1

[0038] According to the investigation and analysis of the vehicle full load condition and the historical data of the adjacent road in the road network, the non-full load and full load proportion of each type of vehicle is obtained, which is shown in Table 1.1-2.

[0039] Table 1.1-2 Non-full load vehicle and full load vehicle proportion (%)

[0040] Vehicle type Class 2 Class 3 Class 4 Class 5 Class 6 Class 7 Class 8 Class 9 Class 10 Class 11 Non-full load vehicle ratio (%) 85.0 90.0 65.0 75.0 55.0 70.0 45.0 60.0 55.0 65.0 Full load vehicle ratio (%) 15.0 10.0 35.0 24.0 45.0 30.0 55.0 40.0 45.0 35.0

[0041] The design index corresponding to the designed pavement is the permanent deformation of asphalt mixture layer and the fatigue cracking of inorganic binder layer. The equivalent design axle load conversion coefficient of non-full load vehicle and full load vehicle corresponding to each vehicle type under different design indexes is obtained, which is shown in Table 1.1-3.

[0042] Table 1.1-3 Non-full load vehicle and full load vehicle equivalent design axle load conversion coefficient

[0043]

[0044] The equivalent design axle load cumulative action times corresponding to the permanent deformation of the asphalt mixture layer is 19,702,681, and the equivalent design axle load cumulative action times corresponding to the fatigue cracking of the inorganic binder layer is 1,366,239,791, according to the formula. The cumulative large passenger car and truck traffic volume of the design lane within the design service life of the road is 12,122,825, and the traffic level belongs to heavy traffic.

[0045] 1.2 Widening of newly built pavement

[0046] Road grade: expressway

[0047] Target reliability index: 1.65

[0048] Initial two-way annual average daily traffic volume of large passenger cars and trucks (vehicles / day): 6467

[0049] Pavement design service life (years): 15

[0050] The period from opening to the first rut repair (years): 8

[0051] Traffic volume annual average growth rate: 2.82%

[0052] Direction coefficient: 0.55

[0053] Lane coefficient: 0.8

[0054] Whole truck proportion: 68%

[0055] Semi-trailer truck proportion: 22%

[0056] Initial annual average daily traffic volume of large passenger cars and trucks on the design lane (vehicles / day): 2845

[0057] The cumulative large passenger car and truck traffic volume of the design lane within the design service life is 1.906074E+07 vehicles, and the pavement design traffic load level is the special heavy traffic load level.

[0058] When checking the fatigue cracking of the asphalt mixture layer, the equivalent design axle load cumulative action times on the design lane within the design service life is 4.370466E+07.

[0059] When checking the fatigue cracking of the inorganic binder stable layer, the equivalent design axle load cumulative action times on the design lane within the design service life is 3.27842E+09.

[0060] When checking the permanent deformation of the asphalt mixture layer, the equivalent design axle load cumulative action times on the design lane within the period from opening to the first rut repair is 2.103807E+07.

[0061] When checking the vertical compressive strain of the top surface of the subgrade, the cumulative number of equivalent design axle loads on the design lane within the design service life is 7.680584E+07.

[0062] 2. Fatigue life of various structures and grouting methods

[0063] Table 2.1 is the calculated bottom tensile stress of the inorganic binder layer when the load is applied to the third lane track belt when the shoulder is reserved 1.25 meters and the shoulder is reserved 1.75 meters. Because the reserved shoulder position is far away from the track belt, when the 1.25-meter shoulder is reserved, the bottom tensile stress of the inorganic binder layer is even significantly lower than that of the new road under the right wheel, and the bottom tensile life of the 1.75-meter layer is equivalent to the bottom tensile life of the old road under the left wheel.

[0064] Table 2.1 Third lane track belt loading inorganic binder layer fatigue cracking check

[0065]

[0066]

[0067] In order to study the influence of various grouting schemes on the service life of the pavement, the most unfavorable way of loading in the middle of the reserved 1.25m old shoulder (which does not exist when the actual 1.25m shoulder is reserved) is used to compare the fatigue cracking life of the inorganic binder layer of different reinforcement schemes. The calculation results are shown in Table 2.2. As shown in the table, the scheme of expanding the hole by 300mm and the row spacing of 40cm records the smallest bottom tensile stress of the base and the largest bending fatigue life. After adjusting the spacing to 80cm, the bending fatigue life is greatly reduced.

[0068] Table 2.2 Fatigue cracking life calculation results of inorganic binder layer

[0069]

[0070] In order to further compare the influence of the actual loading state on the bottom tensile stress of the shoulder base at the most unfavorable position, the case of reserving the shoulder 225cm, four rows of holes, the right three rows with a spacing of 40cm, and the leftmost row with a spacing of 65cm is calculated. The calculation conditions are as follows. From the table, it can be seen that the effect of expanding the hole is more obvious than that of reducing the spacing for reinforcement.

[0071] The 2.25-meter overlap is located directly below the double wheels on the third lane's wheel track. Without reinforcement, the flexural stress at the bottom of the layer would be very high, resulting in a flexural life less than half of the design life. Among all reinforcement options, the 300mm enlarged hole has the greatest effect on reducing flexural stress, even though its spacing is much larger than other options. It still achieves the required displacement life. The 70mm small-diameter, small-spacing reinforcement option has little impact on flexural stress, with a flexural life only two-thirds of the design life. While the 200mm enlarged hole option, with a smaller spacing than the 300mm option, still has a shorter flexural life than the 70mm hole option, it is significantly longer than the 70mm hole option.

[0072] 2.25m inorganic binder layer bottom tensile stress

[0073]

[0074]

[0075] In the actual project implementation, to eliminate the weak edges of the base layer, a 200cm overlap was adopted. Based on the preliminary calculations and the results of the test road at Huizhou West Service Area, and considering the overall cost, according to... Figure 1 The hole layout method is calculated for the scheme of expanding the hole by 300mm. As shown in the FWD back calculation results, the soil modulus increases by 100-200% after grouting. Therefore, three soil moduli of 60MPa, 120MPa and 180MPa are set for calculation.

[0076] As shown in the table below, the unreinforced pavement cannot meet the design flexural life requirements of the base course, while all three 300mm solutions meet the design flexural life requirements. Increasing the subgrade modulus increases the flexural life by 12-25%. The grouting reinforcement solution shown in the figure is recommended.

[0077] Retain 2m of wheel track in the third lane with applied inorganic binder layer and tensile stress at the bottom.

[0078]

[0079] 3. Scheme Design

[0080] (1) In terms of the retained width, the 1.25-meter width is far away from the wheel track of the third lane, and the bending tensile stress is very small, and the service life exceeds the level of the new road. The 1.75-meter width is close to the wheel track at the edge, and the bending tensile stress increases significantly. The bending tensile stress is close to that of the new road, but the service life is reduced, approaching the level of the old road with the whole structure.

[0081] (2) 2.25m width edge is just below the wheel track, the bending tensile stress increases significantly, the life is quite different from the new and old road. If no measures are taken, the bending tensile fatigue life requirement cannot be met. Compared with the grouting, the bending tensile stress of the 300mm hole expansion decreases most obviously, followed by the 200mm hole expansion, and the 70mm hole expansion has little difference with the non-grouting. The 200mm and 70mm hole expansion schemes cannot meet the design bending tensile fatigue life, and the 70mm hole expansion has a larger gap.

[0082] (3) The bottom consolidation is more important, which affects the life by about 20-30%. The bottom layer grouting and higher pressure grouting are necessary.

[0083] (4) 2.0m reservation, the bending tensile stress is significantly affected by the soil modulus. If the soil modulus increases by 1-2 times as the FWD back calculation result, the life increases by 12-25%.

[0084] Suggestions:

[0085] (1) Reserving 1.25m soil shoulder is very safe, and the closed interface can be simply grouted

[0086] (2) The wider the reservation is, the closer to the third lane wheel track, and the greater the influence on the base life is.

[0087] (3) When the reservation width is more than 2m, if no reinforcement is taken, the bending tensile life of the base cannot meet the requirement. Using 70mm small diameter dense piles, the bending tensile life of the base is improved limitedly, and still cannot meet the requirement. When the 170mm drilling, 300mm hole expansion, three rows of holes, row spacing (distance between adjacent hole centers of the same row) 40-50cm, and longitudinal spacing (distance between adjacent hole centers of the same row) 1.1m are adopted, the bending tensile life of the base is significantly improved, and can meet the requirement.

[0088] (4) Due to the cost limitation and construction space limitation, the 300mm hole expansion is difficult to implement. It is difficult to further improve the shoulder base life.

[0089] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the specification of the present application.

Claims

1. A shallow bed of roadbed reaming split grouting structure reinforcement layout, characterized in that, The several drill holes are divided into multiple rows, each row of drill holes corresponds to each other, the several drill holes form multiple columns, the drill holes are punched into the old road surface layer and the old road base layer, and the hole expansion is performed in the filled soil roadbed layer from the drill hole.

2. The enhanced layout of the shallow roadbed reaming split grouting structure according to claim 1, characterized in that, The diameter of the drill hole is 110-200mm, and the diameter of the expanded hole is 250-500mm.

3. The enhanced layout of the shallow roadbed reaming split grouting structure according to claim 1, characterized in that, The distance between the centers of adjacent drill holes in one row of drill holes is 100-150cm.

4. The enhanced layout of the shallow roadbed reaming split grouting structure according to claim 1, characterized in that, The distance between the centers of adjacent rows of drill holes is 35-130cm.

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