Method for detecting single-pile compression bearing capacity of inclined steel pipe pile

Abstract

The invention discloses a method for detecting single-pile compressive bearing capacity of inclined steel pipe piles. The method comprises the steps that S1, the two inclined steel pipe piles with the same inclination angle and opposite directions are arranged; s2, a stacking platform is constructed above the two steel pipe inclined piles, a force component device is arranged at the bottom of the stacking platform, the force component device is provided with two thrust planes, and the two thrust planes are perpendicular to the axes of the two steel pipe inclined piles correspondingly; s3, loading devices are arranged between the two thrust planes and the pile heads of the two inclined steel pipe piles correspondingly; s4, the two loading devices are controlled to conduct synchronous loading, so that the two steel pipe inclined piles bear axial pressure; horizontal component forces generated by synchronous loading are mutually counteracted at the component force device, and generated vertical resultant forces are balanced by the counterforce device; and S5, test data are collected through a monitoring system, and the single-pile compression bearing capacity of the steel pipe inclined pile is determined according to the test data. According to the invention, the complex stress problem which is difficult to deal with in an inclined pile test is ingeniously converted into the vertical stress problem which can be solved by utilizing a mature pile loading platform.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel pipe inclined pile bearing capacity detection test, in particular to a detection method for single pile compressive bearing capacity of steel pipe inclined pile. BACKGROUND

[0002] In the field of pile foundation engineering, the determination of single pile vertical compressive bearing capacity is a key link in the design, and the accuracy of its value is directly related to the safety of the upper structure and the economy of the project. As the most intuitive and most reliable method for detecting the bearing capacity, the static load test has a very mature technical system, such as the counterforce device, the loading method and the data acquisition, and complete provisions have been formed in standards such as “Technical Code for Testing of Building Foundation Piles” (JGJ106-2014) for vertical piles. With the improvement of adaptability to complex geological conditions in the field of construction engineering, steel pipe inclined piles are widely used in foundation pit support, bridge foundation and other engineering scenes due to their advantages in resisting lateral displacement and optimizing foundation stress.

[0003] However, steel pipe inclined piles face a huge bottleneck in bearing capacity detection. Since the existing mature and reliable static load test method and device system are “tailored” for vertical piles. The core counterforce providing method (such as the pile loading method and the anchor pile method) is based on the assumption of vertical force transmission. The inclination characteristics of inclined piles make their stress mechanism fundamentally different from that of vertical piles, resulting in structural incompatibility and force mode mismatch when using traditional static load test devices for inclined piles.

[0004] Therefore, in current engineering practice, the detection of single pile compressive bearing capacity of inclined piles still generally relies on indirect methods such as empirical estimation of geological reports or high-strain dynamic detection. These methods have a large degree of presumption and limited accuracy, which may cause safety hazards due to overestimation or unnecessary economic waste due to underestimation. SUMMARY

[0005] Therefore, the present application provides a detection method for single pile compressive bearing capacity of steel pipe inclined pile, which can fundamentally solve the compatibility problem between traditional static load test and steel pipe inclined pile, and provides a direct and reliable detection method for bearing capacity evaluation of inclined piles.

[0006] The scheme provided by the present application includes:

[0007] A detection method for single pile compressive bearing capacity of steel pipe inclined pile, comprising the following steps:

[0008] S1, arranging two steel pipe inclined piles with the same inclination angle and opposite directions;

[0009] S2, a loading platform is constructed above the two steel pipe piles, the bottom of the loading platform is provided with a force splitting device, the force splitting device has two thrust planes, and the two thrust planes are perpendicular to the axes of the two steel pipe piles respectively;

[0010] S3, a loading device is arranged between each of the two thrust planes and the pile head of the two steel pipe piles;

[0011] S4, the two loading devices are controlled to be synchronously loaded, so that the two steel pipe piles bear axial pressure; the horizontal component forces generated by the synchronous loading are counteracted at the force splitting device, and the vertical resultant force is balanced by the counterforce device;

[0012] S5, test data are collected through a monitoring system, and the single-pile compressive bearing capacity of the steel pipe pile is determined according to the test data.

[0013] As a further optional solution, the loading platform comprises a steel base and a plurality of counterweights stacked on the steel base, and the loading platform is removed after the test is completed.

[0014] As a further optional solution, the force splitting device is a transversely arranged triangular prism-shaped steel structure, and the inside of the force splitting device is filled with cement slurry.

[0015] As a further optional solution, the force splitting device is welded by steel plates, and the inside of the force splitting device is provided with stiffening rib plates.

[0016] As a further optional solution, the two loading devices are oil hydraulic jacks of the same specification.

[0017] As a further optional solution, a fixed support is welded at the pile head of the steel pipe pile, and the fixed support is used to fix the loading device to ensure that the center of the resultant force of the loading device coincides with the axis of the pile body.

[0018] As a further optional solution, the fixed support comprises a pile head plate, an arc-shaped supporting plate for supporting the loading device, and a plurality of vertical stiffening ribs; the pile head plate is welded to the end of the steel pipe pile; the arc-shaped supporting plate is welded to the pile head plate; and the vertical stiffening ribs are welded vertically between the pile head plate and the steel pipe pile body.

[0019] As a further optional solution, the vertical stiffening ribs are at least four.

[0020] As a further optional solution, the monitoring system comprises a displacement sensor for monitoring the settlement of the pile top and a strain sensor for monitoring the strain of the pile body.

[0021] Compared with the prior art, the method for detecting the single-pile compressive bearing capacity of the steel pipe pile has at least the following beneficial effects:

[0022] 1. Direct static load test of inclined pile is realized for the first time: the method successfully solves the fundamental problem of "incompatibility" in structure and stress mode between traditional vertical pile static load test system and inclined pile. Through the innovative design of "symmetrical arrangement of inclined pile" combined with "force splitting device", the complex stress problem difficult to handle in inclined pile test is ingeniously transformed into vertical stress problem that can be solved by mature pile loading platform, thus providing a special method for direct and reliable static load test of inclined pile for the first time.

[0023] 2. The detection result is direct, accurate and reliable: the method directly measures the compressive ultimate bearing capacity of the steel pipe inclined pile through static load test, and the data obtained truly reflects the actual working condition under the interaction of pile and soil, which is more accurate and reliable than the indirect methods such as geological report empirical estimation and high strain dynamic detection, and provides an authoritative basis for engineering design, greatly guarantees the safety of the project, and avoids the economic risk caused by improper bearing capacity value.

[0024] 3. Force system balance is efficient, and the test process is safe and stable: two inclined piles with the same inclination angle and opposite directions are symmetrically and synchronously loaded, so that the harmful horizontal components of force generated by the two jacks are internally counteracted at the force splitting device. This design eliminates the risk of instability of the test device due to bearing of large horizontal force, and ensures the safety of the entire test process and the stability of the data.

[0025] 4. The device is simple, easy to operate and cost-effective: the advantage of the method lies in its "ingenious idea" rather than "complexity". It maximizes the reuse of the vertical pile pile-up reaction system, which is technically very mature and has clear operation specifications, and only adds a simple force splitting device to achieve the function. The device is easy to build, and the pile-up platform can be dismantled and recycled after the test is completed, so the overall cost is low and it has great promotional value.

[0026] 5. Compatible with specifications, strong expandability: the loading, data collection and judgment criteria of the method can follow the principles of existing specifications (such as JGJ106-2014), which is easy for engineering and technical personnel to understand and implement, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is an implementation structure schematic diagram of a single pile compressive bearing capacity detection method of a steel pipe inclined pile according to an embodiment of the present application;

[0028] Figure 2 is a structural schematic diagram (perspective) of a force splitting device according to an embodiment of the present application;

[0029] Figure 3 is a sectional view schematic diagram of A-A in Figure 2

[0030] ​Figure 4 is Figure 2 a sectional view of B-B in figure

[0031] Figure 5 is a structural schematic view of the fixed support of the embodiment of the present application arranged on the steel pipe inclined pile;

[0032] In the figure: 1, steel pipe inclined pile;

[0033] 2, loading platform; 21, steel base; 22, counterweight;

[0034] 3, force distribution device; 31, stiffening rib plate; 311, grouting hole;

[0035] 4, loading device;

[0036] 5, fixed support. DETAILED DESCRIPTION

[0037] The following examples are intended to illustrate the present application but not to limit the scope of the present application.

[0038] In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "back", "vertical", "horizontal" and the like indicate the orientation or positional relationship shown in the drawings based on the orientation or positional relationship, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0039] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or can be integrated; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium; can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "under" the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "over" and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "under" and "under" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0041] The specific embodiments of the present application are described in further detail below in conjunction with the accompanying drawings and examples.

[0042] An embodiment of the present application shows a method for detecting the single-pile compressive bearing capacity of a steel pipe inclined pile. The related structure in the implementation process can refer to Figures 1-5 The method comprises the following steps:

[0043] Step S1, arranging two steel pipe inclined piles 1 with the same inclination angle and opposite directions;

[0044] The same inclination angle means that the included angle of the two steel pipe inclined piles 1 with the vertical direction is consistent, and the included angle is set to 30°-60° in the embodiment. The opposite directions mean that the inclination directions of the two piles are opposite. The purpose is to build a foundation structure that can balance the horizontal component force. By arranging the same inclination angle and opposite directions, the horizontal component forces generated by the two piles during subsequent loading are equal in size and opposite in direction, which fundamentally solves the problem that the horizontal component force of the inclined pile cannot be balanced in the traditional static load test, and provides a structural condition for the stable development of the static load test of the inclined pile.

[0045] Step S2, building a pile-up platform 2 above the two steel pipe inclined piles 1, and the bottom of the pile-up platform 2 is provided with a component force device 3, and the component force device 3 has two thrust planes, and the two thrust planes are perpendicular to the axes of the two steel pipe inclined piles 1, respectively;

[0046] The pile-up platform 2 is used to provide the counterforce required by the test, and the vertical resultant force generated by the loading is balanced by the pile-up weight of the bearing platform, so as to meet the demand of the counterforce for the static load test. The purpose of setting the component force device 3 is to establish a precise interface for load transmission. The design that the two thrust planes are perpendicular to the pile axes can ensure that the load is transmitted along the axial direction of the pile, and avoid that the test data is distorted due to load deviation.

[0047] Step S3, respectively arranging a loading device 4 between the two thrust planes and the pile heads of the two steel pipe inclined piles 1;

[0048] The loading device 4 is used as a force output component, and needs to be arranged between the component force device 3 and the pile head, so as to ensure that the counterforce of the component force device 3 can be converted into the axial pressure on the pile body, and ensure the controllability of the load application.

[0049] Step S4, controlling the two loading devices 4 to perform synchronous loading, so that the two steel pipe inclined piles 1 bear the axial pressure; the horizontal component forces generated by the synchronous loading are mutually balanced at the component force device 3, and the vertical resultant force is balanced by the counterforce device;

[0050] The synchronous loading can ensure the synchronous increase of the loads of the two piles, so that the horizontal components are always offset to each other and the force interference in the horizontal direction is eliminated; meanwhile, the vertical resultant force is transmitted to the pile loading platform 2 through the main beam and balances with the reaction force of the platform, so that the overall stability of the test system is ensured and the instability phenomenon in the loading process is avoided.

[0051] In step S5, the test data are collected by the monitoring system, and the single-pile compressive bearing capacity of the steel pipe inclined pile 1 is determined according to the test data.

[0052] In summary, the method of the embodiment can successfully solve the fundamental problem of the incompatibility between the traditional vertical pile static load test system and the inclined pile in structure and stress mode. Through the innovative design of “symmetrical arrangement of inclined piles” combined with “force component device 3”, the complex stress problem difficult to handle in the inclined pile test is ingeniously transformed into the vertical stress problem that can be solved by the mature pile loading platform 2.

[0053] The method directly measures the compressive ultimate bearing capacity of the steel pipe inclined pile 1 through the static load test, and the data obtained truly reflect the actual working condition under the interaction of pile and soil. The result is more accurate and reliable than the indirect methods such as geological report experience estimation and high-strain dynamic detection, which provides an authoritative basis for engineering design, greatly guarantees the safety of the project, and avoids the economic risks caused by improper bearing capacity valuation.

[0054] The two inclined piles with the same inclination angle and opposite directions are symmetrically and synchronously loaded, so that the harmful horizontal components generated by the two jacks are internally offset to each other at the force component device 3. This design eliminates the risk of instability of the test device due to bearing of the huge horizontal force, and ensures the safety of the entire test process and the stability of the data.

[0055] The advantage of the method lies in its “ingenious idea” rather than “complexity”. It maximizes the reuse of the vertical pile pile loading reaction system which is very mature in technology and has clear operation specifications, and only adds a simple force component device 3 to realize the function. The device is easy to build, and the pile loading platform 2 can be removed and recycled after the test is completed, which is low in overall cost and has great promotional value.

[0056] The loading, data collection and judgment criteria of the method can follow the principles of existing specifications (such as JGJ106-2014), which is easy for engineering and technical personnel to understand and implement, and has a wide application prospect.

[0057] In some embodiments, as shown in Figure 1 The pile loading platform 2 includes a steel base 21 and a plurality of counterweight blocks 22 stacked on the steel base 21, which is removed after the test is completed.

[0058] The steel base 21 provides a solid, flat and uniformly distributed load rigid foundation for the entire pile platform 2. The steel base 21 is usually a lattice platform made of steel sections (such as I-beams, H-beams) as the main beam and the secondary beam welded or spliced together. Its size and structure can be calculated according to actual needs to ensure that it can withstand the gravity of all counterweight blocks 22 above and the vertical reaction force generated during the test without excessive deformation. Its role is to avoid the counterweight block 22 directly pressing on the ground or pile foundation, and to ensure the stability and reliability of the reaction force transmission.

[0059] The counterweight block 22 can be made of stone or reinforced concrete block. By stacking multiple counterweight blocks 22 on the steel base 21, a large enough counterbalancing force required for the test can be flexibly adjusted.

[0060] In some embodiments, as shown in Figures 2-4 The force splitting device 3 is a transversely placed triangular prism steel structure, and its interior is filled with cement slurry.

[0061] As shown in Figure 2 The cross section of the force splitting device 3 is an inverted triangle, and two thrust planes are formed on the oblique lower side, which has high structural stability and strong deformation resistance. The interior of the force splitting device 3 is filled with cement, which aims to enhance the overall stiffness and local pressure capacity of the force splitting device 3.

[0062] Preferably, the force splitting device 3 is welded from steel plates, and a stiffening rib plate 31 is arranged inside. As shown in Figure 3 and Figure 4 The stiffening rib plate 31 is provided with a grouting hole 311, which facilitates the filling of the interior of the force splitting device 3 with cement slurry to ensure that the cement slurry and the steel structure are fully combined and jointly stressed.

[0063] In some embodiments, the two loading devices 4 are oil hydraulic jacks of the same specification. The oil hydraulic jack is a loading device 4 commonly used in static load tests. The two oil hydraulic jacks can be supplied with oil by the same oil pump system to ensure that their output and lifting speed are always synchronized, thereby ensuring that the load applied to the two inclined piles is always equal, achieving complete cancellation of horizontal forces and correct superposition of vertical forces.

[0064] In some embodiments, as shown in Figure 1 and Figure 5 A fixed support 5 is welded to the pile head of the steel pipe inclined pile 1, which is used to fix the loading device 4 to ensure that the center of gravity of the loading device 4 coincides with the pile shaft axis. In this way, eccentric load caused by the misalignment of the loading device 4 and the steel pipe inclined pile 1 can be avoided. Eccentric load can generate additional bending moment in the pile shaft, which seriously affects the accuracy of the test data, and may even cause the test pile to be damaged due to bending moment before reaching the true compressive bearing capacity.

[0065] Specifically, the fixed support 5 comprises a pile head plate, an arc-shaped supporting plate for supporting the loading device 4, and vertical stiffening ribs; the pile head plate is welded to the end of the steel pipe inclined pile 1; the arc-shaped supporting plate is welded to the pile head plate; and the vertical stiffening ribs are welded vertically between the pile head plate and the steel pipe column body. Preferably, the vertical stiffening ribs are provided with at least 4 pieces.

[0066] Among them, the pile head plate provides a base plane, the arc-shaped supporting plate defines the position of the jack, and the vertical stiffening ribs ensure the connection strength, all of which work together to ensure the accurate implementation of the axial loading.

[0067] In some embodiments, the monitoring system (not shown) comprises displacement sensors for monitoring the settlement of the pile top and strain sensors for monitoring the strain of the pile body.

[0068] Among them, the specific implementation details of the monitoring system, including but not limited to the selection criteria of strain sensors and displacement sensors (such as accuracy level, range requirement), the layout position and fixing method of sensors on the pile body, the frequency of data acquisition and recording requirements, and the judgment criteria of data validity, etc. can refer to the technical provisions of "Technical Code for Building Foundation Pile Detection" (JGJ 106-2014), so it is not repeated here.

[0069] In the above embodiments, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0070] The above is only the preferred embodiment of the present application, it should be pointed out that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and replacements can also be made, which should be considered as the protection scope of the present application.

Claims

1. A method for detecting the single-pile compression bearing capacity of a steel pipe oblique pile, characterized by, The method comprises the following steps: S1, arranging two steel pipe inclined piles with the same inclination and opposite directions; S2, constructing a loading platform above the two steel pipe inclined piles, the bottom of the loading platform is provided with a force splitting device, the force splitting device has two thrust planes which are perpendicular to the axes of the two steel pipe inclined piles respectively; S3, arranging a loading device between each of the two thrust planes and the pile head of the two steel pipe inclined piles respectively; S4, controlling the two loading devices to perform synchronous loading so that the two steel pipe inclined piles bear axial pressure; the horizontal components of the synchronous loading cancel each other at the force splitting device, and the vertical resultant force is balanced by the counterforce device; S5, collecting test data through a monitoring system, and determining the single-pile compression bearing capacity of the steel pipe inclined pile according to the test data.

2. The method according to claim 1, wherein the loading platform comprises a steel base and a plurality of counterweights stacked on the steel base, and the loading platform is removed after the test is completed.

3. The method according to claim 1, wherein the force splitting device is a horizontally arranged triangular prism-shaped steel structure, and the inside of the force splitting device is filled with cement slurry.

4. The method according to claim 3, wherein the force splitting device is welded by steel plates, and the inside of the force splitting device is provided with stiffening rib plates.

5. The method according to claim 1, wherein the two loading devices are oil hydraulic jacks with the same specifications.

6. The method according to claim 5, wherein a fixed support is welded on the pile head of the steel pipe inclined pile, and the fixed support is used to fix the loading devices to ensure that the center of the resultant force of the loading devices coincides with the axis of the pile body.

7. The method according to claim 6, wherein the fixed support comprises a pile head plate, an arc-shaped support plate for supporting the loading devices, and a plurality of vertical stiffening ribs; the pile head plate is welded with the end of the steel pipe inclined pile; the arc-shaped support plate is welded on the pile head plate; and the vertical stiffening ribs are welded vertically between the pile head plate and the steel pipe column body.

8. The method according to claim 7, wherein the vertical stiffening ribs are at least four.

9. The method according to claim 1, wherein the monitoring system comprises displacement sensors for monitoring the settlement of the pile top and strain sensors for monitoring the strain of the pile body. ​ ​ ​ ​ ​ ​ ​ ​

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