JP5845861B2 - Loading test method for soil cement column wall - Google Patents

Description

  The present invention relates to a load test method for soil cement column wall.

  In order to make effective use of the soil cement column wall, such as using the soil cement column wall as a main pile, an in-situ loading test of the soil cement column wall was conducted, and the support capacity of the soil cement column wall was increased. It is known to confirm (for example, refer nonpatent literature 1). This document describes the bearing capacity of soil cement column walls by carrying out a loading test (so-called static loading test) using a reaction force pile method using a loading girder (reaction girder), a reaction force pile and a hydraulic jack. Is disclosed.

Summary of Academic Lectures of the Japanese Architectural Society (Tohoku) August pp. 667-670 "Studies on the use of piles in soil cement walls (Part 1 Vertical loading test results on sandy ground)", "Soil cement wall Study on the use of piles (Part 2: Results of vertical loading test on viscous ground)

  In the static loading test, since a loading girder and a reaction force pile are required, the testing apparatus becomes large, and the installation space is widened. Therefore, it was difficult to carry out the test in a narrow area such as the outer periphery of the building.

  This invention is made | formed in view of the said situation, and provides the loading test method of the soil cement column wall which can be implemented also in a narrow area | region.

The soil cement column wall loading test method according to the present invention is a soil cement column wall loading test method to be used as a pile for permanent construction , and a weight is dropped to evaluate the bearing capacity characteristics as a pile. Then, a rapid loading test of the pile loaded on the core material of the soil cement column wall is performed.

In the load test method of the soil cement column wall, in the core material , the friction is applied above the surface of the height of the head of the pile supporting the building constructed in the region surrounded by the soil cement column wall. a shaft member is subjected to cutting, equipped with instruments at the bottom of the shaft member, may be carried out rapidly loading test the by dropping the weight on the shaft member.

In the load test method of the soil cement column wall, the core is located below the height surface of the head of the pile supporting the building constructed in the region surrounded by the soil cement column wall. It may be configured to be detachable from the material, and may be removed after the rapid loading test.

  ADVANTAGE OF THE INVENTION According to this invention, the loading test method of the soil cement pillar row wall which can be implemented also in a narrow area | region can be provided.

It is the elevation view and top view which show the test apparatus used in the loading test of the soil cement column wall which concerns on one Embodiment. It is a graph which shows the relationship between the static load and displacement amount of a soil cement column wall. It is a graph which shows the relationship between the bearing strength of the lower end of soil cement pillar row wall, and ground hardness (N value). It is a graph which shows the load-displacement amount curve obtained by a rapid loading test, and a static load-displacement amount curve. It is a figure which shows the procedure of the loading test of the soil cement pillar row wall which concerns on other embodiment. (A)-(E) is a figure which shows the construction procedure of the soil cement column wall which concerns on other embodiment, and the procedure of a loading test. (A)-(F) is a figure which shows the construction procedure of the soil cement pillar row wall which concerns on other embodiment, and the procedure of a loading test. It is a figure which shows the coupling mechanism which couple | bonds the lower end of a Yatco and the upper end of a lower pile. It is a figure which shows the coupling mechanism which couple | bonds the lower end of a Yatco and the upper end of a lower pile. It is a top view which shows the other Example of a friction cut.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an elevation view and a plan view showing a test apparatus 10 used in a load test of a soil cement column wall 1 according to an embodiment. As shown in this figure, a test apparatus 10 is an apparatus for carrying out a quick loading test (sude static test) of a soft cushion weight drop method, and a weight 12 is used as a core material of a soil cement column wall 1. It drops on the cushioning material 14 installed in the head of the H-shaped steel 2 and applies a pushing force due to a rapid load in the vertical direction to the soil cement column wall 1.

  The test apparatus 10 includes a weight 12 and a cushioning material 14, a support 16 that supports the weight 12 so as to be movable up and down, a wire rope fixing device 18 suspended from the crane 3, and a wire rope 20 from the wire rope fixing device 18. The electromagnet 22 suspended at the base, the pedestal 24 for installing the cushioning material 14 and the like on the head of the H-shaped steel 2, the load cell 26 installed on the pedestal 24, the target 28 for the displacement meter, and the accelerometer 30; And an optical displacement meter 32.

  In the test apparatus 10, the electromagnet 22 is lifted up to a predetermined height while being magnetically coupled to the upper portion of the weight 12, and then the electromagnet 22 is turned off to drop the weight 12 onto the cushion material 14. At that time, the vertical load is measured by the load cell 26, the acceleration of the head of the soil cement column wall 1 is measured by the accelerometer 30, and the vertical displacement of the head of the soil cement column wall 1 is measured by the optical displacement meter 32. It is measured.

  Using the test apparatus 10 having the above-described configuration, the vertical load acting on the soil cement column wall 1, the vertical displacement of the head of the soil cement column wall 1, and the head of the soil cement column wall 1 Measure vertical acceleration. And based on the measurement result, the relationship between the static load and displacement of the soil cement column wall 1 (see FIG. 2), the bearing strength and the ground hardness (N value) of the lower end of the soil cement column wall 1 and The bearing force characteristics such as the relationship (see FIG. 3) are evaluated.

  FIG. 4 is a graph showing a load-displacement curve and a static load-displacement curve obtained by the test. As indicated by the solid line in this graph, the load-displacement curve directly obtained by the test shows the dynamic behavior of the H-section steel 2 affected by the loading speed, and the static load of the H-section steel 2 -In order to estimate the displacement curve (illustrated with a broken line), the dynamic effect due to the inertial force of the H-shaped steel 2 due to rapid load and the strain rate dependence of the ground resistance is based on the measured value of the accelerometer 30 and the like. An analysis to estimate and subtract the effect from the measurement results is required. As an analysis method for that purpose, a method of representing the behavior of the H-shaped steel 2-ground system, such as the unloading point method, with a one-mass system model, or a primary method in which the H-shaped steel 2 is expressed by an elastic bar and the ground resistance is expressed by a spring and a dashpot. Examples include the original wave analysis method and the dynamic finite element method.

  Here, a rapid loading test is performed to evaluate the bearing capacity of the soil cement column wall 1 by determining whether the soil cement column wall 1 can be used as a main pile or a soil cement column. This is because, when the row wall 1 is used as a main pile, the share of the supporting force with the new pile is determined.

  As described above, in this embodiment, in order to evaluate the bearing capacity characteristics of the soil cement column wall 1 used for the installation, a quick loading test of a soft cushion weight dropping method is performed. Here, the rapid loading test does not require a reaction force pile or a reaction force girder like a loading test by a reaction force pile method (so-called static loading test). Therefore, compared with the case where a static loading test is performed, the test apparatus can be simplified and the installation space for the test apparatus can be reduced. It becomes possible. Moreover, by using the soil cement column wall 1 as a main pile, the number of new piles can be reduced, and effects such as a reduction in construction cost and a shortening of the construction period can be obtained.

  FIG. 5 is a diagram illustrating a procedure of a loading test of the soil cement column wall 1 according to another embodiment. As shown in this figure, in this embodiment, when the soil cement column wall 1 is constructed, the foundation bottom (the region surrounded by the soil cement column wall 1) of the H-shaped steel 2 to be subjected to the loading test is constructed. A friction-cut covering material is applied to the upper portion of the pile head that supports the building, which is the height of the head of the pile. That is, in the portion above the foundation bottom of the soil cement column wall 1, the friction cut layer 4 is interposed between the H-shaped steel 2 to be subjected to the loading test and the soil cement layer. Examples of the friction cut covering material include a composite of a water-absorbing polymer.

  Further, the accelerometer 30 and the strain gauge 34 are installed at the height of the base bottom of the H-shaped steel 2. In addition, the load cell 26 is installed in the base 24 installed in the head of the H-shaped steel 2 similarly to the above-mentioned embodiment. Then, the test apparatus 10 is installed on the H-shaped steel 2 to be subjected to the load test, and the weight 12 is dropped on the cushioning material 14 on the head of the H-shaped steel 2 so that the H-shaped steel 2 rapidly in the vertical direction. Apply indentation force by load. At this time, the acceleration in the vertical direction at the depth position of the pile head of the soil cement column wall 1 is measured by the accelerometer 30, and the depth position of the pile head of the soil cement column wall 1 by the strain gauge 34. The vertical strain at is measured.

  As described above, in the loading test of the soil cement column wall 1 according to the present embodiment, the accelerometer 30 and the strain gauge 34 are installed at the height of the pile head, and the soil cement column wall 1 By inserting the friction cut layer 4 between the H-shaped steel 2 to be subjected to the load test and the soil cement layer in the upper part of the foundation bottom, the indentation force due to the friction between the soil cement column wall 1 and the ground can be obtained. For example, the influence of the friction on the measurement result can be suppressed. Therefore, even when loading with respect to the height position of the pile head of the soil cement column wall 1, the bearing capacity characteristics of the soil cement column wall 1 as a pile after completion of the building can be appropriately evaluated.

  6 (A) to 6 (E) and FIGS. 7 (A) to 7 (F) are diagrams showing a construction procedure and a loading test procedure of the soil cement column wall 1 according to another embodiment. First, as shown in FIGS. 6A and 6B, a hole is drilled by an excavator and cement milk is injected into the hole. And as shown in Drawing 6 (C) and (D), lower pile 5 which is H type steel embed | buried deeper than a pile head is lowered in a hole with a crane, and this lower pile 5 is made to remove the head from a hole. In the extended state, it is fixed with the flap angle 9 and the steel frame fixture. Then, as shown in FIGS. 6 (E) and 7 (A), the Y-tco 6 that is H-shaped steel is suspended by a crane and placed above the lower pile 5, and the lower end of the Yatco 6 and the upper end of the lower pile 5 And combine. In addition, the accelerometer 30 and the strain gauge 34 are installed at the lower end of the Yatco 6. In addition, the load cell 26 is installed in the base 24 like the above-mentioned embodiment.

  Here, the friction cut layer is interposed between the Yatco 6 and the soil cement layer by coating the surface of the Yatco 6 with a friction cut covering material. Examples of the friction cut covering material include a composite of a water-absorbing polymer.

  8 and 9 are views showing a coupling mechanism 40 that couples the lower end of the Yatco 6 and the upper end of the lower pile 5. As shown in these drawings, the coupling mechanism 40 couples the steel plates 42 and 44 fixed to one surface and the other surface of the web 6A of the Yatco 6, and the steel plates 42 and 44 and the upper end of the lower pile 5 respectively. A pin 46 and a lock member 48 for energizing, and a spring 49 for biasing the pin 46.

  The steel plates 42 and 44 face each other with the web 6 </ b> A interposed therebetween and protrude downward from the web 6 </ b> A, and the upper end of the web 5 </ b> A of the lower pile 5 is inserted between the steel plates 42 and 44. Holes 42 </ b> A, 44 </ b> A, 5 </ b> B through which the pins 46 are inserted are opened at the lower portions of the steel plates 42, 44 and the upper end of the web 5 </ b> A of the lower pile 5. The spring 49 is a compression coil spring, and one end thereof is fixed around the hole 44 </ b> A of the steel plate 44. The rear end of the pin 46 is fixed to the other end of the spring 49. Here, when the spring 49 is in a compressed state, the pin 46 is inserted into the holes 42A, 44A, and 5B, and the tip protrudes forward of the steel plate 42. On the other hand, when the spring 49 is in a natural length state, the spring 49 comes out of the holes 42A and 5B.

  Further, the tip of the pin 46 has an enlarged diameter, and the lock member 48 is formed with a U-groove 48 </ b> A that is narrower than the tip of the pin 46 and wider than the shaft diameter of the pin 46. The pin 46 is urged toward the rear side of the steel plate 44 by the elastic force of the spring 49. For this reason, when the pin 46 is pulled out forward of the steel plate 42 and the shaft portion of the pin 46 is fitted into the U groove 48A of the lock member 48, the pin 46 is fixed by the lock member 48, and the upper end of the lower pile 5 and the Yatco 6 The lower end is connected.

  Further, a rope 48B is attached to the opposite side of the U groove 48A of the lock member 48. For this reason, when the lock member 48 is pulled up with the rope 48B, the shaft portion of the pin 46 is pulled out from the U groove 48A of the lock member 48, and the pin 46 is pulled out from the holes 42A and 5B by the elastic force of the spring 49. The connection state between the upper end of the knives and the lower end of the yatco 6 is released. Further, a screw hole 46A for screwing a shaft-shaped jig is formed at the tip of the pin 46, and the pin 46 can be pulled out forward of the steel plate 42 by the jig.

  After the upper end of the lower pile 5 and the lower end of the Yatco 6 are combined by the connecting mechanism 40 as described above, the lower pile 5 is built up to the drilling depth as shown in FIGS. The wire that has suspended 6 is removed from the Yatco 6. And it pushes down 1 m by hitting the Yatco 6 and the lower pile 5 with the monoken 7.

  Then, as shown in FIG. 7D, the test apparatus 10 is installed on the head of the yatco 6, and a rapid load is loaded on the lower pile 5 through the yatco 6. At this time, the acceleration in the vertical direction at the depth position of the pile head of the soil cement column wall 1 is measured by the accelerometer 30, and the depth position of the pile head of the soil cement column wall 1 by the strain gauge 34. The vertical strain at is measured.

  Then, as shown in FIGS. 7E and 7F, after the lock member 48 is pulled up to release the connection between the upper end of the lower pile 5 and the lower end of the yatco 6 by the coupling mechanism 40, the yatco 6 is opened with a crane. Pull up from. At this time, since the friction cut layer is interposed between the Yatco 6 and the soil cement layer, and the Yatco 6 and the soil cement layer are cut off, the Yatco 6 can be easily pulled out and removed.

  As described above, in the loading test of the soil cement column wall 1 according to the present embodiment, the accelerometer 30 and the strain gauge 34 are installed at the height of the pile head, and the soil cement column wall 1 The friction is measured by reducing the indentation force caused by the friction between the soil cement column wall 1 and the ground by interposing a friction cut layer between the Yatco 6 and the soil cement layer in the upper part of the foundation bottom The effect on the results was reduced. Therefore, it can load with respect to the height position of the pile head of the soil cement column wall 1 and can appropriately evaluate the bearing capacity characteristics of the soil cement column wall 1 as a pile after the building is completed. .

  Moreover, the accelerometer 30 and the strain gauge 34 can be collected by pulling out and removing the Yacco 6 in which the accelerometer 30 and the strain gauge 34 are installed after the loading test. The removed Yatco 6 can be diverted. Therefore, the cost required for the loading test can be reduced.

  In addition, the above-mentioned embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof. For example, in the above-described embodiment, the friction cut layer is formed in order to reduce the friction between the upper portion of the H-shaped steel 2 and the Yatco 6 and the soil cement layer. For example, as shown in FIG. A steel pipe 8 may be embedded in the wall 1, and an upper portion of the H-shaped steel 2 or a Yatco 6 may be installed in the steel pipe 8.

1 Soil cement column wall, 2 H type steel (core material), 3 crane, 4 friction cut layer, 5 lower pile (core material), 5A web, 5B hole, 6 Yatco, 6A web, 7 monoken, 8 steel pipe, 9 Flutter angle, 10 test equipment, 12 weights, 14 cushioning material, 16 struts, 18 wire rope fixing device, 20 wire rope, 22 electromagnet, 24 pedestal, 26 load cell, 28 target, 30 accelerometer (instrument), 32 optical Displacement meter, 34 Strain gauge (instrument), 40 Coupling mechanism, 42 Steel plate, 42A hole, 44 Steel plate, 44A hole, 46 pin, 46A Screw hole, 48 Lock member, 48A U groove, 48B rope, 49 Spring

Claims (3)

It is a loading test method for soil cement column wall used as a pile of main construction,
In order to evaluate the bearing capacity characteristics as a pile, a load test method for a soil cement column wall is performed, in which a pile is loaded on the core material of the soil cement column wall by dropping a weight. . Among the core, wherein the shaft member is subjected to friction cut above the height of the surface of the head of the pile to support the soil cement pillar buildings constructed in the region surrounded by the columns wall of said shaft member The load test method for a soil cement column wall according to claim 1, wherein an instrument is installed at a lower portion and the rapid loading test is performed by dropping a weight onto the shaft member. The shaft member is configured to be attachable to and detachable from a core member below a height surface of a pile head supporting a building constructed in an area surrounded by the soil cement column wall, 3. The soil cement column wall loading test method according to claim 2, wherein the soil cement column wall is removed after performing the loading test.

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