CN209816941U - Pile foundation soil layer limit side frictional resistance test system - Google Patents
Pile foundation soil layer limit side frictional resistance test system Download PDFInfo
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- CN209816941U CN209816941U CN201920412813.XU CN201920412813U CN209816941U CN 209816941 U CN209816941 U CN 209816941U CN 201920412813 U CN201920412813 U CN 201920412813U CN 209816941 U CN209816941 U CN 209816941U
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Abstract
The utility model provides a pile foundation soil layer limit side frictional resistance test system, including one insert beat the steel in the soil layer of the examination side frictional resistance that awaits measuring protect a section of thick bamboo, the steel protects a bottom portion and is equipped with one and is located the intraformational concrete pile of test soil, and concrete pile bottom is equipped with the one deck soil void, and the welding has a reaction frame on the steel protects a section of thick bamboo inner wall, is equipped with a top jack between concrete pile top and the reaction frame. The utility model discloses accessible jack is to concrete pile test pile stage loading, tests out the limit side frictional resistance of concrete test pile to long and the pile footpath of pile according to the concrete test pile calculate with the unit area limit side frictional resistance on this soil layer, provide the foundation for bridge pile foundation parameter design. The utility model discloses rely on the steel to protect a counter-force of a section of thick bamboo self, need not become the stake and can test, easy operation, it is with low costs, and all can be suitable for in land and aquatic environment.
Description
Technical Field
The utility model belongs to the technical field of bridge pile foundation construction, a system for testing pile foundation soil layer limit side frictional resistance is related to.
Background
The construction quality of the pile foundation directly influences the stability of the main structure of the bridge. Because the pile foundation is buried in the soil layer, can't discover construction quality problem through observing, so in case the pile foundation goes wrong, can bring unpredictable risk for the bridge operation, consequently it is very important to test the bearing capacity of pile foundation in the work progress.
The concrete friction pile mainly provides supporting force by means of friction force between the side wall of the pile foundation and a rock-soil layer, so that testing of the friction force between the concrete pile foundation and the soil layer before construction is the most important construction link, reasonable mechanical parameters can be provided for design of the pile foundation, and the stress performance of the pile foundation is ensured. The traditional concrete pile test method mainly comprises two methods: firstly, a stacking method; the second is an anchor pile method.
The pile loading method is to load a certain load on the pile top of the pile to test the bearing capacity of the pile foundation. The material demand of the stacking method is large, mechanical equipment is needed for the operation of the stacking material, the engineering quantity is large, the material stacking quantity is not easy to control, and the accuracy of the test result is influenced; the anchor pile method is that the anchor piles are inserted and driven around the piles, then the anchor piles are used as platforms to arrange reaction frames, and a jack is used for pushing the reaction frames to carry out back pressure on the pile foundation so as to test the bearing capacity of the pile foundation. The construction of the anchor pile is limited by geological conditions, and the anchor pile is often pulled up in the test process, so that the test fails.
In addition, the two methods both need to provide a complete test pile, and the test cost is high due to the high construction cost and long working time of the pile foundation. In addition, the two methods are more suitable for land environment, and have higher difficulty in testing the pile foundation in water.
Disclosure of Invention
The utility model aims to provide a pile foundation side frictional resistance test system that experimental cost is low, fast, easy operation, and all be suitable for in land and aquatic to the not enough of present pile foundation side frictional resistance test method existence.
The technical scheme of the utility model as follows:
the utility model provides a pile foundation soil layer limit side frictional resistance test system which characterized in that: the device comprises a steel pile casing, wherein the lower end of the steel pile casing is inserted into a soil layer to be tested for lateral frictional resistance, a concrete pile located in a test soil layer is arranged at the bottom of the steel pile casing, a layer of soil is arranged at the bottom of the concrete pile, a reaction frame is welded on the inner wall of the steel pile casing, and a pushing jack is arranged between the top of the concrete pile and the reaction frame.
In the system, in order to increase the resistance between the steel casing and the soil layer, a layer of cement mortar can be injected between the outer wall of the steel casing and the soil layer.
In the system, in order to increase the resistance between the steel casing and the soil layer, during specific implementation, a plurality of through holes are annularly arranged on the wall of the steel casing, a transverse key is arranged in each through hole, the transverse key is a section of steel with a certain length, one end of the transverse key is transversely inserted into the soil layer outside the steel casing from the inside of the steel casing along the through hole, and the other end of the transverse key is welded with the steel casing; a plurality of transverse keys are divided into at least two layers on the wall of the steel protecting cylinder, at least 4 transverse keys are uniformly arranged on each layer in the circumferential direction, and the transverse keys on adjacent layers are staggered.
In the above-mentioned system, for increasing the steel protect a section of thick bamboo and with the soil layer between the resistance, during the concrete implementation, can the steel protect the upper end outer wall hoop equidistance welding of a section of thick bamboo and have 4 back pressure brackets, alternate an stock on every bracket, the rear end of stock passes through the nut with the back pressure bracket and fixes, and the front end anchor head slant is inserted and is squeezed into in the outer soil layer of steel protect a section of thick bamboo.
The utility model discloses need not become the stake and can test, utilize concrete pile and reaction frame that set up in the steel protects a section of thick bamboo to and the steel protects the counter-force that a section of thick bamboo self provided, can test the frictional resistance of each ground layer of pile position respectively, can provide important foundation for construction pile foundation length, bearing capacity design according to the test result, simple structure, easily operation, test construction cycle is short, and is with low costs; is not limited by environment, is suitable for both land and water, and has higher popularization and use values.
Drawings
Fig. 1 is a schematic diagram of the system structure of the present invention;
fig. 2 is a schematic view of the vertical structure of the reaction frame of the present invention.
Fig. 3 is a schematic plan view of the reaction frame according to the present invention.
FIG. 4 is a plan view of the arrangement of the steel casing cross key;
fig. 5 is a plan view of the arrangement mode of the upper end back pressure bracket and the anchor rod of the steel casing.
Detailed Description
As shown in fig. 1, the utility model provides a pair of pile foundation soil layer limit side frictional resistance test system, protect a section of thick bamboo 1 including a steel, 1 lower extreme of a steel protects and is inserted and beat in the soil layer of the side frictional resistance that awaits measuring, and 1 bottom of a steel protects is equipped with one and is located the intraformational concrete pile 2 of test soil, concrete pile bottom is equipped with one deck virtual soil 3, and the welding has a reaction frame 4 on the steel protects a section of thick bamboo inner wall, concrete pile 3 top with be equipped with a top jack 5 between the reaction frame 4.
The utility model discloses regard as the test stake with the concrete pile, test pile foundation soil layer limit side frictional resistance. In order to ensure that the steel pile casing and the concrete pile are stressed uniformly, when the concrete pile is arranged, the axis of the concrete pile 2 is coincided with the axis of the steel pile casing 1.
The effect of the loose soil 3 at the bottom of the concrete pile is that firstly, when vertical load is applied to the concrete pile 2 in subsequent tests, the concrete pile is ensured to bear the vertical load only by means of side friction force, and the end resistance is negligible; and secondly, the concrete pile can sink when the vertical load borne by the concrete pile exceeds the bearing capacity of the concrete pile, so that the limit side frictional resistance of the concrete pile can be accurately obtained.
The structure of the reaction frame is shown in fig. 2 and 3, and comprises two cross; an inclined support rod 43 is welded at the intersection of the upper end of each vertical rod 42 and the two cross rods.
When the jack 5 is installed, a next cushion plate can be arranged between the top of the concrete pile 2 and the bottom of the pushing jack 5, an upper cushion plate is arranged between the top of the pushing jack 5 and the bottom of the reaction frame 4, and the axis of a piston rod of the pushing jack is coincided with the axes of the concrete pile and the steel casing.
The utility model discloses an utilize the steel to protect resistance between a section of thick bamboo and the soil layer and provide the counter-force and carry out the back pressure to the concrete pile, consequently the steel protects a section of thick bamboo and can provide sufficient resistance, is crucial to the test success.
As shown in fig. 1, in order to increase the resistance of the side frictional resistance of the steel casing 1, a layer of cement mortar 6 may be injected between the outer wall of the steel casing and the soil layer after the steel casing is inserted and beaten.
Further, a transverse key can be arranged on the steel casing to increase the resistance between the steel casing and the soil layer, and the specific method comprises the following steps:
before the steel protects a section of thick bamboo and inserts and beat, set up a plurality of through-holes in advance on the section of thick bamboo wall of steel protects a section of thick bamboo, a plurality of through-holes divide at least two-layer on the steel protects a section of thick bamboo wall, and every layer hoop evenly sets up at least 4, and adjacent layer through-hole staggers the setting.
As shown in fig. 1 and 4, after the steel casing is inserted and beaten and rock soil in the steel casing is removed, a transverse key 7 is inserted and beaten outwards from each through hole in the steel casing 1. The transverse key 7 is a section of section steel with a certain length, the height of the cross section of the transverse key is equal to or slightly less than that of the through hole, the front end of the transverse key is inserted into a soil layer on the outer side of the steel casing by a certain length, and the rear end of the transverse key is positioned in the steel casing and welded with the steel casing, so that the transverse key and the steel casing do not generate relative displacement after being installed.
In an embodiment of the present invention, the through hole provided on the steel casing is rectangular, and the transverse key is made of a buckling channel steel. Circular through holes can also be adopted, and the transverse keys are steel tubes.
In order to facilitate the insertion and the hitting of the transverse key, one end of the transverse key 7 inserted into the soil layer outside the steel casing 1 is an inclined plane.
Further, the anchor rod can be selected to increase the resistance between the steel casing and the soil layer according to the geological condition of the pile foundation position, and the concrete method comprises the following steps:
as shown in fig. 1 and 5, 4 back pressure brackets 8 are circumferentially and equidistantly welded on the outer wall of the upper end of the steel casing 1, an anchor rod 9 is inserted into each back pressure bracket 8, the rear end of each anchor rod 9 is fixed with the back pressure brackets 8 through nuts, and the anchor head at the front end of each anchor rod 8 is obliquely inserted into a soil layer outside the steel casing.
The utility model is used for during to pile foundation soil layer limit side frictional resistance test, concrete process as follows:
and starting the jack 5 for graded loading, pushing the reaction frame 4 upwards, and carrying out back pressure on the concrete pile 2. Each stage of loading lasts for a certain time, the top of the steel casing is observed, it is determined that the steel casing 1 does not generate upward displacement, and then whether a piston rod of the jack extends or not is observed; if the steel casing does not move upwards and the piston rod of the jack does not extend after the first-stage loading lasts for a certain time, the concrete pile is proved to not move, and the next-stage loading can be carried out when the loading force of the first-stage loading is within the side frictional resistance bearing range of the concrete pile.
(6) If the steel casing is not upwardly displaced and the piston rod of the jack is extended in the primary loading process, the concrete pile 2 is downwardly displaced, and the loading force of the jack exceeds the limit side frictional resistance between the concrete test pile and the test soil layer. And taking the jack loading force of the previous stage loaded at the stage as the limit side frictional resistance of the concrete test pile.
(7) According to the jack loading force F of the previous stage of displacement of the concrete test pile, the unit area limit side friction resistance between the concrete test pile and the soil layer is calculated, and the calculation formula is as follows:
q＝F/2πrL；
wherein r is the radius of the concrete test pile, L is the length of the concrete test pile, and q is the unit area limit side frictional resistance of the concrete test pile and the soil layer.
By the method, the unit area limit side frictional resistance of each soil layer at the construction position of the bridge pile foundation can be tested. According to the design load of the bridge pile foundation, the data obtained by the test and the thickness of each soil layer are combined, the area of the side wall of the pile foundation, which is required to bear the design load, can be calculated, and the parameters such as the pile diameter, the length (depth penetrating into the soil layer) and the like of the pile foundation can be conveniently and reasonably designed.
Claims (8)
1. The utility model provides a pile foundation soil layer limit side frictional resistance test system which characterized in that: the device comprises a steel pile casing, wherein the lower end of the steel pile casing is inserted into a soil layer to be tested for lateral frictional resistance, a concrete pile located in a test soil layer is arranged at the bottom of the steel pile casing, a layer of soil is arranged at the bottom of the concrete pile, a reaction frame is welded on the inner wall of the steel pile casing, and a pushing jack is arranged between the top of the concrete pile and the reaction frame.
2. The pile foundation soil layer limit side frictional resistance test system of claim 1, characterized in that: the reaction frame comprises two cross; an inclined support rod is welded at the intersection of the upper end of each vertical rod and the two cross rods.
3. The pile foundation soil layer limit side frictional resistance test system of claim 1, characterized in that: and the axis of the concrete pile coincides with the axis of the steel casing.
4. The pile foundation soil layer limit side frictional resistance test system of claim 3, characterized in that: a next cushion plate is arranged between the top of the concrete test pile and the bottom of the pushing jack, and an upper cushion plate is arranged between the top of the pushing jack and the bottom of the reaction frame; and the axis of a piston rod of the pushing jack is superposed with the axes of the concrete pile and the steel casing.
5. The pile foundation soil layer limit side frictional resistance test system of claim 1, characterized in that: and a layer of cement mortar is injected between the outer wall of the steel casing and the soil layer.
6. The pile foundation soil layer limit side frictional resistance test system of claim 1, characterized in that: the wall of the steel casing is annularly provided with a plurality of through holes, each through hole is internally provided with a transverse key, each transverse key is a section of profile steel with a certain length, one end of each transverse key is transversely inserted into a soil layer outside the steel casing along the through hole from the inside of the steel casing, and the other end of each transverse key is welded with the steel casing; a plurality of transverse keys are divided into at least two layers on the wall of the steel protecting cylinder, at least 4 transverse keys are uniformly arranged on each layer in the circumferential direction, and the transverse keys on adjacent layers are staggered.
7. The pile foundation soil layer limit side frictional resistance test system of claim 6, characterized in that: the end part of one end of the transverse key inserted into the soil is an inclined plane.
8. The pile foundation soil layer limit side frictional resistance test system of claim 1, characterized in that: the steel protects the upper end outer wall hoop equidistance welding of a section of thick bamboo and has 4 back pressure brackets, alternates an stock on every bracket, the rear end of stock passes through the nut with the back pressure bracket and fixes, and the front end anchor head slant is inserted and is squeezed into in the steel protects the outer soil layer of a section of thick bamboo.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920412813.XU CN209816941U (en) | 2019-03-28 | 2019-03-28 | Pile foundation soil layer limit side frictional resistance test system |
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| CN201920412813.XU CN209816941U (en) | 2019-03-28 | 2019-03-28 | Pile foundation soil layer limit side frictional resistance test system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109914494A (en) * | 2019-03-28 | 2019-06-21 | 中交路桥建设有限公司 | A kind of pile foundation soil layer utmost tip resistance test macro |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109914494A (en) * | 2019-03-28 | 2019-06-21 | 中交路桥建设有限公司 | A kind of pile foundation soil layer utmost tip resistance test macro |
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