Micro-drilled rock-embedded steel pipe infusion, flat hand home Jiang Jiangmin Minjing Guangzhou Luban Construction Waterproof Reinforcement Professional Company. Guangzhou. Department of Construction Engineering, South China University of Technology, 5106, Guangzhou. 510,1 Abstract describes the construction technology, equipment and design of a new type of underpinning pile mini-drilled rock-inserted steel pipe cast-in-place pile, which has been applied in a series of projects. It is verified that it has the advantages of high vertical bearing capacity of a single pile, simple construction, high quality and reliable construction, and additional subsidence caused by the replaced structure. It has wide applicability and popularization value.
Lifting and translation, design and construction and research work of foundation pit support, 1 Introduction In the foundation underpinning project, the foundation underpinning is a common and effective method. It is a conversion structure that converts the upper structure to the first part or part. Hexun chooses the type of underpinning pile that is passed to the deep soil and rock through the underpinning pile foundation. For the underpinning structural system, it is directly related to whether the underpinning structure is safe and reliable. The underpinning project is economically reasonable; on the other hand, the selection of the underpinning pile type is complicated. It needs to be determined based on the geological conditions of the site. The basic form of the old underpinning structure, the surrounding environment of the structural characteristics and other comprehensive factors are determined. Commonly used underpinning in China, type 12 has artificial bored cast-in-place bored piles, anchor-type steel pipe or reinforced concrete static pressure, top bearing type steel pipe static pressure, driven-in miniature steel pipe pile rotary immersed pipe injection, tree root, There are always some types of micro-drilled holes in the design and construction that are difficult to overcome, which is easy to cause cloth and difficulty; large diameter, although the bearing capacity is high, but it is easy to cause additional settlement of the building during construction. Especially in the soft ten and backfilled formations, the additional subsidence caused by the construction cannot meet the design requirements, and the equipment technology is also severely restricted to prevent construction. For this reason, based on research and analysis of existing underpinnings, based on the theoretical level, after years of engineering practice, the author has developed a new type of micro drilling with a small diameter, high bearing capacity and simple construction, which causes additional subsidence and a small scope of application. Rock-socketed steel piles. It uses a small spin rig to form 013, 22, the pile hole into the rock to set a depth, place the steel pipe towards the length, and then cast grouting fine stone concrete 1 Cheng 2 pile type structure and construction 2, type structure micro drilling rock embedded steel pipe pouring It is caused by the steel pipe grouting concrete outside the steel pipe and the cement leaking out of the cub.
The steel pipe should be selected from the universal 3 type seamless or welded joints in the construction. 8. The connection of the steel bamboo can be welded by the inner section or the outer section of the steel pipe.
2.
Welded steel pipe with welded joints. When the concrete is made into a hole to a clear design depth, put grouting bamboo to the bottom of the hole and inject cement with a water-cement ratio of 357. The slurry will overflow 1 hole and then put into graded gravel. Pull bamboo and insert rubble while dropping.
In order to form 択 concrete. Suppose that the strength is generally 153. When the cement slurry consolidation outside the steel pipe is poured into the cement slurry, the slurry overflows from the elongated slurry hole at the bottom of the steel pipe and the circular overflow hole at the upper part. Knot body. The main owner said that the wrapped steel pipe prevents the corrosion of the steel pipe and strengthens the construction process between the steel pipe and the hole wall soil rock.
Steel pipe production and welding 2 people. 3 others.
3 Machinery equipment process equipment includes drilling grouting electromechanical welding machine and so on. The drilling rig can be modified by using ordinary light type 2 geological drilling rig. The grouting machine can use the ordinary 8 comment 250 or 150 mud paddle pump, and the grouting pressure is screwed on the bearing capacity characteristics and working mechanism of 0.1033 piles. 3.1 The vertical bearing capacity of the piles. And design requirements. The diameter of the borehole is commonly 015017022. When the pile ends into the middle and the micro, and the body needs to pass through the thick and weak soil layer. The stability of piles in weak soil layers should also be checked. The typical field test of Hong Guoruo Qian analyzed the vertical bearing capacity of 1 pile as 1 test, and the maximum test load value was 450 001. The maximum settlement of the pile top was 415. The rebound value of the pile body after grading unloading was large , Accounting for 4050 of the total settlement, the deformation of each pile is also ⑵ labor organization because the pile type is simple. 1 Bo Chengqihe is in the elastoplastic stage.
The team completed the drilling rig drilling steel pipe processing and welding cement slurry to prepare the grouting 2 passed the test, 25 characteristic curve analysis. For each test and throwing gravel for work, 8 people are needed for soil operations. There are 3 rigs. The piles, the lines did not appear to drop sharply. The straight line turns in the engineering project with the characteristics of plant age. The bearing layer of the aperture enters the bearing layer, the number of trials, 2 rebounds, the maximum settlement capacity, the design value, the diameter, the depth, m. Shipyard equipment sandstone jacking project Qingyuan Hengshi post and telecommunications granite flying building foundation reinforcement Yunfu a building plus stone firestone correction correction project Shantou residential Dahuagang stone building foundation reinforcement Xiajiu shopping sandstone core reconstruction project Guangzhou Dezheng Road top mudstone correction correction In the Yangpu Mapu cave dwelling granite house building reconstruction project, all test piles on the 5th line have a tail-bending phenomenon, and the settlement time of the piles is shorter.
3 The design value of bearing capacity of each is determined according to the deformation requirements of.
3.2. In terms of working mechanism, due to the small size of the cross-section, in the actual project, the child reduction is simplified, the factory calculation and test machine acceptance, and the settlement of the split piles dominate. Most of the deformations are the shrinkage deformation of the pile body. According to the force transfer mechanism of the pile's elasticity, the lateral friction resistance of the pile is better than the resistance of the rock-socket section. When the body load increases to a certain degree, the lateral friction The resistance will be fully exerted. At this time, if the body load continues to increase, the increased load is provided by the resistance of the rock-embedded section of the pile, and the resistance of the rock-embedded section is composed of the side resistance of the rock-embedded section and the resistance of the end of the rock-embedded section; On the other hand, due to the depth of the type of rock-embedded, the ratio of the pile diameter 0 is generally greater than 58, the lateral resistance of the rock-embedded section will be higher, the steep descending line segment of the line 1 is divided up by the intersection of the horizontal coordinate and the lateral friction resistance And, the resistance analysis of the rock-socketed section, the resistance of the rock-socketed section is much greater than the friction resistance of the lateral soil layer, the model should belong to the friction end bearing 3.3 single, vertical bearing capacity empirical formula. The empirical formula of the vertical bearing capacity of a single pile is based on the working mechanism of the pile type. The vertical bearing capacity of the single pile is composed of the resistance of the end of the rock-socket section of the rock-socket section of the side soil friction resistance, and the design formula is the standard of the side resistance of the soil. Value; 1; standard value of rock saturated uniaxial compressive strength; is, body embedded depth, end area; 1 is, body circumference is the thickness of pile body passing through the third layer of soil is the side resistance and embedded Correction coefficient of resistance at the rock end. , 1 value, 3, 7, 2 value 0.3, 0.5., Value. It depends on the degree of rock hardness and the degree of hole clearance. The greater the hardness of the rock and the smaller the degree of crushing, the less the sediment at the bottom of the hole and the higher the value, and the lower the value. For, the conversion factor between the standard value of the vertical bearing capacity and the design value is taken as the value. 1.2. For household stakes and. For the foundation above the pile, take 1. For, the following foundation takes 1.2.
The strength design value of the check calculation formula of the pile body is 1. The cross-sectional area of ​​the grouting concrete pile body; the design value of the artificial steel bamboo compressive strength is the cross-sectional area of ​​the steel pipe, and the reduction factor of the bearing capacity considering the buckling coefficient. Generally, the influence not considered is 1.0. When the standard value of the ultimate load capacity of the foundation around the pile is less than 5, the influence of buckling should be considered. Generally taken as 79; the ferrule system made of steel and bamboo concrete 4 application example 4.1 project, a six-storey brick-concrete structure residential building in Shantou, with a construction area of ​​about 1600 2, reinforced concrete strip foundation, using rubble and local under the foundation The ground was treated by the method of beating wood. The rubble in the east was partially placed on the rock layer, and the rubble in the west was placed on the wood, top, wood, and length 4. Before the building was completed and put into use, it was found that the eastern wall of the building appeared Inclined cracks, with a crack width of about 51 and cracks found on some floor slabs. Observation of the building is made obliquely. It was found that the lattice 1 of the building was severely tilted, tilted to the south by 85, and tilted to the west by 15. Afterwards, a unit was asked to carry out heavy grouting treatment on the foundation, but after half a year of settlement and tilt observation, the building tilted out to the maximum amount Up to 105 direction called the maximum tilt up to 1821 Yan Pavilion 4. The cracks on the floor and wall have also increased and increased.
Unit drive 5. Press Deficiency = 14, the value is based on the preliminary survey at the design stage and the geological report of the supplementary survey after the cracks appear in the building. The site is on the peninsula, the stratum is complex, the ground is large and the small lone rock. The distribution of the soil and rock layers is from the top to the bottom. It is a recent plain soil layer, with a thickness of 1.03., 1 is mainly silt, loose; the mud-sand layer is 2.012. Thick, containing shells, saturated, fluid plastic; granite residual soil layer , Thickness 0.91.51; granite layer, buried depth on top. The rock layer buried in the east is called deep buried.
4.2 Analysis of accident cause and choice of plan 1 The analysis is based on the calculation and review of the building structure. If the cracks are as follows: â‘ For shallow foundations, the distribution of the soft soil layer is extremely uneven due to the site and stratum, and the top of the rock layer is buried The ups and downs on the plane are large, and the shallow foundation is prone to uneven settlement. Although the foundation is treated with rubble and beating, the rubble on the east side of the building is placed on the rock layer, and the deformation of the foundation is very small, while the rubble on the west side is placed on 4.0, 1 long layer. The ground clump will increase the additional stress of the foundation and increase the deformation of the foundation after the stone is thrown, which will cause the inclination of the building. After asking Yu about building 0. Mining 13 dense grouting treatment. However, it is difficult to control the difference in foundation settlement for the existing solid foundation at the foundation end, on the contrary. During the construction of grouting, Ten River will destroy the body, and the building will undergo additional sinking before the forced cast. Make the deformation of the building increase.
2 The choice of plan is based on the characteristics of brick-concrete structure buildings and the causes of accidents. After analysis, if the uneven settlement of the building is not controlled in time, the building may be seriously damaged. Because the side deformation of the foundation is stable, the side deformation is still very large. To reasonably twist the differential deformation. The foundation must be replaced. The option to transfer all the loads to the rock stratum through the pile foundation must be satisfied and the requirements must be met in the shortest possible time. Can quickly and effectively underload. To make the building completely stable, the bearing layer at the end of the pile must be a rock layer. â‘¡ The additional settlement of the building caused by the pile foundation construction should be as small as possible; the large stratum rubble was thrown under the cluster. The pile foundation must be able to pass through this layer; there are many horizontal and vertical walls in the brick-concrete structure, and the equipment should be able to meet the indoor construction requirements, due to the large amount of load underpinning. The site in the building is narrow and the cloth supply is limited in location, requiring underpinning, single base, high vertical bearing capacity â‘¥ underpinning, the connection between the base and the original foundation should not change the stress state of the original foundation as much as possible.
To meet all requirements. Through the analysis and comparison of all underpinnings and types, it is believed that only micro-drilled rock-socketed steel-tube cast-in-place piles combined with anchor rib caps can reasonably underpinning and meet the requirements.
4.3 Implementation and effect of plan 1 The design and construction of plan was calculated and analyzed, and a total of 48 022, micro-drilled rock-filled steel pipe cast-in-place piles were arranged. Among them, 36 steel pipes are 018, and 6512 steel pipes are 0165. 5. The design bearing capacity of single pile is 650 Xin. The connection of the 500-muscle cap is to cut out part of the original foundation first. Applying claw glue anchor bars and welding to connect the original foundation transverse bars. The placement of cast-in-strength concrete to form anchor-reinforced concrete bearing piles and the connection of large-scale foreign pavilions 5.6.
Construction monitoring and reinforcement effect. Before strengthening the foundation of the building, the slope and settlement of the building will be observed with the stomach of the relevant unit. In order to analyze the effect during construction and after reinforcement. A total of 16 foundation settlement observation points and 8 tilt observation points were arranged. Observation and analysis of each pile and the 3rd day after the completion of the construction of the pile anchor cap. The foundation settlement at this location has been basically stabilized.
During the construction process, the static load test of the strip pile is carried out by the method of providing the reaction force of the anchor reinforcement cap, and the bearing capacity of the anchor reinforcement cap and the pile can be fully satisfied by the design.
4 After a long period of observation six months after the completion of the project, the overall tilt of the building is exactly the same as the observation on the seventh day after completion. The cumulative maximum settlement increase of the foundation is 0.51. After the foundation is stable, the repaired wall without any cracks, the cracks in the floor slabs, and the repaired floor cracks are also carried out by Nongke. Meet the requirements of reinforcement design.
Conclusion of the original structural column 5 The mini-drilled rock-socketed steel pipe cast-in-place pile has a single pile with high bearing capacity and is simple and convenient. It can be constructed on the ground where the rubble is thrown away. It can also reasonably solve the construction problems encountered in karst caves in limestone strata, and has a wide range of application and popularization value.
The pile type is a small-diameter cast-in-place pile, and it needs to enter a certain depth of the rock layer. The author believes that this pile type is more suitable for the site with shallow rock layer.
Since all tests are carried out, the bearing capacity of the reinforced engineering pile is to determine the design bearing capacity of the single pile according to the deformation conditions satisfied by the single project, and the ultimate failure was not achieved during the test. , The ultimate bearing capacity is still to be tested.
1 Zeng Guoxi et al. Ground treatment manual. Beijing China Building Industry Press, 1988 2 Ye Shulin and others. Basic underpinning technology. Beijing China Railway Press, 19913 Zeng Guoxi et al. Pile foundation engineering manual. Beijing China Construction Industry Press, 1995 4 Zhu Jinying, Chen Longzhu, Ge Tabo. Fitting analysis of static load test data of piles in layered foundation. Chinese Journal of Geotechnical Engineering, China Engineering Construction Standardization Association. Structural design and construction regulations for concrete-filled steel tubes. Beijing China Planning Press
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